Conventional 3D staging PET/CT in CT simulation for lung cancer: impact of rigid and deformable target volume alignments for radiotherapy treatment planning.

PubMed

Hanna, G G; Van Sörnsen De Koste, J R; Carson, K J; O'Sullivan, J M; Hounsell, A R; Senan, S

2011-10-01

Positron emission tomography (PET)/CT scans can improve target definition in radiotherapy for non-small cell lung cancer (NSCLC). As staging PET/CT scans are increasingly available, we evaluated different methods for co-registration of staging PET/CT data to radiotherapy simulation (RTP) scans. 10 patients underwent staging PET/CT followed by RTP PET/CT. On both scans, gross tumour volumes (GTVs) were delineated using CT (GTV(CT)) and PET display settings. Four PET-based contours (manual delineation, two threshold methods and a source-to-background ratio method) were delineated. The CT component of the staging scan was co-registered using both rigid and deformable techniques to the CT component of RTP PET/CT. Subsequently rigid registration and deformation warps were used to transfer PET and CT contours from the staging scan to the RTP scan. Dice's similarity coefficient (DSC) was used to assess the registration accuracy of staging-based GTVs following both registration methods with the GTVs delineated on the RTP PET/CT scan. When the GTV(CT) delineated on the staging scan after both rigid registration and deformation was compared with the GTV(CT)on the RTP scan, a significant improvement in overlap (registration) using deformation was observed (mean DSC 0.66 for rigid registration and 0.82 for deformable registration, p = 0.008). A similar comparison for PET contours revealed no significant improvement in overlap with the use of deformable registration. No consistent improvements in similarity measures were observed when deformable registration was used for transferring PET-based contours from a staging PET/CT. This suggests that currently the use of rigid registration remains the most appropriate method for RTP in NSCLC.

99mTc-HMPAO SPECT of the brain in mild to moderate traumatic brain injury patients: compared with CT--a prospective study.

PubMed

Nedd, K; Sfakianakis, G; Ganz, W; Uricchio, B; Vernberg, D; Villanueva, P; Jabir, A M; Bartlett, J; Keena, J

1993-01-01

Single photon emission computed tomography (SPECT) with Technetium-99m hexamethyl propylenamine oxime (Tc-99m-HMPAO) was used in 20 patients with mild to moderate traumatic brain injury (TBI) to evaluate the effects of brain trauma on regional cerebral blood flow (rCBF). SPECT scan was compared with CT scan in 16 patients. SPECT showed intraparenchymal differences in rCBF more often than lesions diagnosed with CT scans (87.5% vs. 37.5%). In five of six patients with lesions in both modalities, the area of involvement was relatively larger on SPECT scans than on CT scans. Contrecoup changes were seen in five patients on SPECT alone, two patients with CT alone and one patient had contrecoup lesions on CT and SPECT. Of the eight patients (50%) with skull fractures, seven (43.7%) had rCBF findings on SPECT scan and five (31.3%) demonstrated decrease in rCBF in brain underlying the fracture. All these patients with fractures had normal brain on CT scans. Conversely, extra-axial lesions and fractures evident on CT did not visualize on SPECT, but SPECT demonstrated associated changes in rCBF. Although there is still lack of clinical and pathological correlation, SPECT appears to be a promising method for a more sensitive evaluation of axial lesions in patients with mild to moderate TBI.

Cranial CT with adaptive statistical iterative reconstruction: improved image quality with concomitant radiation dose reduction.

PubMed

Rapalino, O; Kamalian, Shervin; Kamalian, Shahmir; Payabvash, S; Souza, L C S; Zhang, D; Mukta, J; Sahani, D V; Lev, M H; Pomerantz, S R

2012-04-01

To safeguard patient health, there is great interest in CT radiation-dose reduction. The purpose of this study was to evaluate the impact of an iterative-reconstruction algorithm, ASIR, on image-quality measures in reduced-dose head CT scans for adult patients. Using a 64-section scanner, we analyzed 100 reduced-dose adult head CT scans at 6 predefined levels of ASIR blended with FBP reconstruction. These scans were compared with 50 CT scans previously obtained at a higher routine dose without ASIR reconstruction. SNR and CNR were computed from Hounsfield unit measurements of normal GM and WM of brain parenchyma. A blinded qualitative analysis was performed in 10 lower-dose CT datasets compared with higher-dose ones without ASIR. Phantom data analysis was also performed. Lower-dose scans without ASIR had significantly lower mean GM and WM SNR (P = .003) and similar GM-WM CNR values compared with higher routine-dose scans. However, at ASIR levels of 20%-40%, there was no statistically significant difference in SNR, and at ASIR levels of ≥60%, the SNR values of the reduced-dose scans were significantly higher (P < .01). CNR values were also significantly higher at ASIR levels of ≥40% (P < .01). Blinded qualitative review demonstrated significant improvements in perceived image noise, artifacts, and GM-WM differentiation at ASIR levels ≥60% (P < .01). These results demonstrate that the use of ASIR in adult head CT scans reduces image noise and increases low-contrast resolution, while allowing lower radiation doses without affecting spatial resolution.

Dynamic CT for Parathyroid Adenoma Detection: How Does Radiation Dose Compare With Nuclear Medicine?

PubMed

Czarnecki, Caroline A; Einsiedel, Paul F; Phal, Pramit M; Miller, Julie A; Lichtenstein, Meir; Stella, Damien L

2018-05-01

Dynamic CT is increasingly used for preoperative localization of parathyroid adenomas, but concerns remain about the radiation effective dose of CT compared with that of 99m Tc-sestamibi scintigraphy. The purpose of this study was to compare the radiation dose delivered by three-phase dynamic CT with that delivered by 99m Tc-sestamibi SPECT/CT performed in accordance with our current protocols and to assess the possible reduction in effective dose achieved by decreasing the scan length (i.e., z-axis) of two phases of the dynamic CT protocol. The effective dose of a 99m Tc-sestamibi nuclear medicine parathyroid study performed with and without coregistration CT was calculated and compared with the effective dose of our current three-phase dynamic CT protocol as well as a proposed protocol involving CT with reduced scan length. The median effective dose for a 99m Tc-sestamibi nuclear medicine study was 5.6 mSv. This increased to 12.4 mSv with the addition of coregistration CT, which is higher than the median effective dose of 9.3 mSv associated with the dynamic CT protocol. Reducing the scan length of two phases in the dynamic CT protocol could reduce the median effective dose to 6.1 mSv, which would be similar to that of the dose from the 99m Tc-sestamibi study alone. Dynamic CT used for the detection of parathyroid adenoma can deliver a lower radiation dose than 99m Tc-sestamibi SPECT/CT. It may be possible to reduce the dose further by decreasing the scan length of two of the phases, although whether this has an impact on accuracy of the localization needs further investigation.

Low-dose head computed tomography in children: a single institutional experience in pediatric radiation risk reduction: clinical article.

PubMed

Morton, Ryan P; Reynolds, Renee M; Ramakrishna, Rohan; Levitt, Michael R; Hopper, Richard A; Lee, Amy; Browd, Samuel R

2013-10-01

In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Children's Hospital), the largest number of patients with this protocol reported to date. All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan. Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Children's Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%. The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

Effect of staff training on radiation dose in pediatric CT.

PubMed

Hojreh, Azadeh; Weber, Michael; Homolka, Peter

2015-08-01

To evaluate the efficacy of staff training on radiation doses applied in pediatric CT scans. Pediatric patient doses from five CT scanners before (1426 scans) and after staff training (2566 scans) were compared statistically. Examinations included cranial CT (CCT), thoracic, abdomen-pelvis, and trunk scans. Dose length products (DLPs) per series were extracted from CT dose reports archived in the PACS. A pooled analysis of non-traumatic scans revealed a statistically significant reduction in the dose for cranial, thoracic, and abdomen/pelvis scans (p<0.01). This trend could be demonstrated also for trunk scans, however, significance could not be established due to low patient frequencies (p>0.05). The percentage of scans performed with DLPs exceeding the German DRLs was reduced from 41% to 7% (CCT), 19% to 5% (thorax-CT), from 9% to zero (abdominal-pelvis CT), and 26% to zero (trunk; DRL taken as summed DRLs for thorax plus abdomen-pelvis, reduced by 20% accounting for overlap). Comparison with Austrian DRLs - available only for CCT and thorax CT - showed a reduction from 21% to 3% (CCT), and 15 to 2% (thorax CT). Staff training together with application of DRLs provide an efficient approach for optimizing radiation dose in pediatric CT practice. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

High pitch third generation dual-source CT: Coronary and Cardiac Visualization on Routine Chest CT

PubMed Central

Sandfort, Veit; Ahlman, Mark; Jones, Elizabeth; Selwaness, Mariana; Chen, Marcus; Folio, Les; Bluemke, David A.

2016-01-01

Background Chest CT scans are frequently performed in radiology departments but have not previously contained detailed depiction of cardiac structures. Objectives To evaluate myocardial and coronary visualization on high-pitch non-gated CT of the chest using 3rd generation dual-source computed tomography (CT). Methods Cardiac anatomy of patients who had 3rd generation, non-gated high pitch contrast enhanced chest CT and who also had prior conventional (low pitch) chest CT as part of a chest abdomen pelvis exam was evaluated. Cardiac image features were scored by reviewers blinded to diagnosis and pitch. Paired analysis was performed. Results 3862 coronary segments and 2220 cardiac structures were evaluated by two readers in 222 CT scans. Most patients (97.2%) had chest CT for oncologic evaluation. The median pitch was 2.34 (IQR 2.05, 2.65) in high pitch and 0.8 (IQR 0.8, 0.8) in low pitch scans (p<0.001). High pitch CT showed higher image visualization scores for all cardiovascular structures compared with conventional pitch scans (p<0.0001). Coronary arteries were visualized in 9 coronary segments per exam in high pitch scans versus 2 segments for conventional pitch (p<0.0001). Radiation exposure was lower in the high pitch group compared with the conventional pitch group (median CTDIvol 10.83 vs. 12.36 mGy and DLP 790 vs. 827 mGycm respectively, p <0.01 for both) with comparable image noise (p=0.43). Conclusion Myocardial structure and coronary arteries are frequently visualized on non-gated 3rd generation chest CT. These results raise the question of whether the heart and coronary arteries should be routinely interpreted on routine chest CT that is otherwise obtained for non-cardiac indications. PMID:27133589

TU-F-18A-06: Dual Energy CT Using One Full Scan and a Second Scan with Very Few Projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, T; Zhu, L

Purpose: The conventional dual energy CT (DECT) requires two full CT scans at different energy levels, resulting in dose increase as well as imaging errors from patient motion between the two scans. To shorten the scan time of DECT and thus overcome these drawbacks, we propose a new DECT algorithm using one full scan and a second scan with very few projections by preserving structural information. Methods: We first reconstruct a CT image on the full scan using a standard filtered-backprojection (FBP) algorithm. We then use a compressed sensing (CS) based iterative algorithm on the second scan for reconstruction frommore » very few projections. The edges extracted from the first scan are used as weights in the Objectives: function of the CS-based reconstruction to substantially improve the image quality of CT reconstruction. The basis material images are then obtained by an iterative image-domain decomposition method and an electron density map is finally calculated. The proposed method is evaluated on phantoms. Results: On the Catphan 600 phantom, the CT reconstruction mean error using the proposed method on 20 and 5 projections are 4.76% and 5.02%, respectively. Compared with conventional iterative reconstruction, the proposed edge weighting preserves object structures and achieves a better spatial resolution. With basis materials of Iodine and Teflon, our method on 20 projections obtains similar quality of decomposed material images compared with FBP on a full scan and the mean error of electron density in the selected regions of interest is 0.29%. Conclusion: We propose an effective method for reducing projections and therefore scan time in DECT. We show that a full scan plus a 20-projection scan are sufficient to provide DECT images and electron density with similar quality compared with two full scans. Our future work includes more phantom studies to validate the performance of our method.« less

Use of PET/CT scanning in cancer patients: technical and practical considerations

PubMed Central

2005-01-01

This overview of the oncologic applications of positron emission tomography (PET) focuses on the technical aspects and clinical applications of a newer technique: the combination of a PET scanner and a computed tomography (CT) scanner in a single (PET/CT) device. Examples illustrate how PET/CT contributes to patient care and improves upon the previous state-of-the-art method of comparing a PET scan with a separate CT scan. Finally, the author presents some of the results from studies of PET/CT imaging that are beginning to appear in the literature. PMID:16252023

Comparison of Conventional Versus Spiral Computed Tomography with Three Dimensional Reconstruction in Chronic Otitis Media with Ossicular Chain Destruction.

PubMed

Naghibi, Saeed; Seifirad, Sirous; Adami Dehkordi, Mahboobeh; Einolghozati, Sasan; Ghaffarian Eidgahi Moghadam, Nafiseh; Akhavan Rezayat, Amir; Seifirad, Soroush

2016-01-01

Chronic otitis media (COM) can be treated with tympanoplasty with or without mastoidectomy. In patients who have undergone middle ear surgery, three-dimensional spiral computed tomography (CT) scan plays an important role in optimizing surgical planning. This study was performed to compare the findings of three-dimensional reconstructed spiral and conventional CT scan of ossicular chain study in patients with COM. Fifty patients enrolled in the study underwent plane and three dimensional CT scan (PHILIPS-MX 8000). Ossicles changes, mastoid cavity, tympanic cavity, and presence of cholesteatoma were evaluated. Results of the two methods were then compared and interpreted by a radiologist, recorded in questionnaires, and analyzed. Logistic regression test and Kappa coefficient of agreement were used for statistical analyses. Sixty two ears with COM were found in physical examination. A significant difference was observed between the findings of the two methods in ossicle erosion (11.3% in conventional CT vs. 37.1% in spiral CT, P = 0.0001), decrease of mastoid air cells (82.3% in conventional CT vs. 93.5% in spiral CT, P = 0.001), and tympanic cavity opacity (12.9% in conventional CT vs. 40.3% in spiral CT, P=0.0001). No significant difference was observed between the findings of the two methods in ossicle destruction (6.5% conventional CT vs. 56.4% in spiral CT, P = 0.125), and presence of cholesteatoma (3.2% in conventional CT vs. 42% in spiral CT, P = 0.172). In this study, spiral CT scan demonstrated ossicle dislocation in 9.6%, decrease of mastoid air cells in 4.8%, and decrease of volume in the tympanic cavity in 1.6%; whereas, none of these findings were reported in the patients' conventional CT scans. Spiral-CT scan is superior to conventional CT in the diagnosis of lesions in COM before operation. It can be used for detailed evaluation of ossicular chain in such patients.

SU-C-206-07: A Practical Sparse View Ultra-Low Dose CT Acquisition Scheme for PET Attenuation Correction in the Extended Scan Field-Of-View

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, J; Fan, J; Gopinatha Pillai, A

Purpose: To further reduce CT dose, a practical sparse-view acquisition scheme is proposed to provide the same attenuation estimation as higher dose for PET imaging in the extended scan field-of-view. Methods: CT scans are often used for PET attenuation correction and can be acquired at very low CT radiation dose. Low dose techniques often employ low tube voltage/current accompanied with a smooth filter before backprojection to reduce CT image noise. These techniques can introduce bias in the conversion from HU to attenuation values, especially in the extended CT scan field-of-view (FOV). In this work, we propose an ultra-low dose CTmore » technique for PET attenuation correction based on sparse-view acquisition. That is, instead of an acquisition of full amount of views, only a fraction of views are acquired. We tested this technique on a 64-slice GE CT scanner using multiple phantoms. CT scan FOV truncation completion was performed based on the published water-cylinder extrapolation algorithm. A number of continuous views per rotation: 984 (full), 246, 123, 82 and 62 have been tested, corresponding to a CT dose reduction of none, 4x, 8x, 12x and 16x. We also simulated sparse-view acquisition by skipping views from the fully-acquired view data. Results: FBP reconstruction with Q. AC filter on reduced views in the full extended scan field-of-view possesses similar image quality to the reconstruction on acquired full view data. The results showed a further potential for dose reduction compared to the full acquisition, without sacrificing any significant attenuation support to the PET. Conclusion: With the proposed sparse-view method, one can potential achieve at least 2x more CT dose reduction compared to the current Ultra-Low Dose (ULD) PET/CT protocol. A pre-scan based dose modulation scheme can be combined with the above sparse-view approaches, which can even further reduce the CT scan dose during a PET/CT exam.« less

Positive Enteric Contrast Material for Abdominal and Pelvic CT with Automatic Exposure Control: What Is the Effect On Patient Radiation Exposure?

PubMed Central

Wang, Zhen J.; Chen, Katherine S.; Gould, Robert; Coakley, Fergus V.; Fu, Yanjun; Yeh, Benjamin M.

2014-01-01

Objective To assess the effect of positive enteric contrast administration on automatic exposure control (AEC) CT radiation exposure in 1) a CT phantom, and 2) a retrospective review of patients. Materials and Methods We scanned a CT phantom containing simulated bowel that was sequentially filled with water and positive enteric contrast, and recorded the mean volume CT dose index (CTDIvol). We also identified 17 patients who had undergone 2 technically comparable CT scans of the abdomen and pelvis, one with positive enteric contrast and the other with oral water. Paired student t-tests were used to compare the mean CTDIvol between scans performed with and without positive enteric contrast. Both the phantom and patient CT scans were performed using AEC with a fixed noise index. Results The mean CTDIvol for the phantom with simulated bowel containing water and positive enteric contrast were 8.2 ± 0.2 mGy, and 8.7 ± 0.1 mGy (6.1% higher than water, p=0.02), respectively. The mean CTDIvol for patients scanned with oral water and with positive enteric contrast were 11.8mGy and 13.1mGy, respectively (p=0.003). This corresponded to a mean CTDIvol which was 11.0% higher (range: 0.0–20.7% higher) in scans with positive enteric contrast than those with oral water in patients. Conclusions When automatic exposure control is utilized for abdominopelvic CT, the radiation exposure, as measured by CTDIvol, is higher for scans performed with positive enteric contrast than those with oral water. PMID:21493028

A Comparison of Angular Values of the Pelvic Limb with Normal and Medial Patellar Luxation Stifles in Chihuahua Dogs Using Radiography and Computed Tomography.

PubMed

Phetkaew, Thitaporn; Kalpravidh, Marissak; Penchome, Rampaipat; Wangdee, Chalika

2018-02-01

 This article aimed to determine and compare the angular values of the pelvic limb in normal and medial patellar luxation (MPL) stifles in Chihuahuas using radiography and computed tomographic (CT) scan, to identify the relationship between pelvic limb angles and severity of MPL. In addition, radiographic and CT images were compared to determine the more suitable method of limb deformity assessment.  Sixty hindlimbs of Chihuahuas were divided into normal and grade 1, 2, 3 and 4 MPL groups. The pelvic limb angles in frontal and sagittal planes were evaluated on radiography and CT scan. Femoral and tibial torsion angles (FTA and TTA) were evaluated only by CT scan. All angles were compared among normal and MPL stifles and between radiography and CT scan.  Based on the CT scan, the mechanical lateral distal femoral angle (mLDFA), anatomical caudal proximal femoral angle (aCdPFA), and TTA were related to the severity of MPL. The mLDFA and TTA were significantly increased ( p  < 0.05) in grade 4 MPL, while the aCdPFA was significantly decreased in grade 2, 3 and 4 MPL groups. There were significant differences of many angles between radiography and CT scan.  The angles related to MPL in Chihuahuas are aLDFA, mLDFA, aCdPFA and TTA. Radiography had some limitations for evaluating pelvic limb angles. The caudocranial radiograph is recommended for the assessment of the distal femoral angles, while the craniocaudal radiograph is for the tibial angles. Schattauer GmbH Stuttgart.

SU-E-I-13: Evaluation of Metal Artifact Reduction (MAR) Software On Computed Tomography (CT) Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, V; Kohli, K

2015-06-15

Purpose: A new commercially available metal artifact reduction (MAR) software in computed tomography (CT) imaging was evaluated with phantoms in the presence of metals. The goal was to assess the ability of the software to restore the CT number in the vicinity of the metals without impacting the image quality. Methods: A Catphan 504 was scanned with a GE Optima RT 580 CT scanner (GE Healthcare, Milwaukee, WI) and the images were reconstructed with and without the MAR software. Both datasets were analyzed with Image Owl QA software (Image Owl Inc, Greenwich, NY). CT number sensitometry, MTF, low contrast, uniformity,more » noise and spatial accuracy were compared for scans with and without MAR software. In addition, an in-house made phantom was scanned with and without a stainless steel insert at three different locations. The accuracy of the CT number and metal insert dimension were investigated as well. Results: Comparisons between scans with and without MAR algorithm on the Catphan phantom demonstrate similar results for image quality. However, noise was slightly higher for the MAR algorithm. Evaluation of the CT number at various locations of the in-house made phantom was also performed. The baseline HU, obtained from the scan without metal insert, was compared to scans with the stainless steel insert at 3 different locations. The HU difference between the baseline scan versus metal scan was improved when the MAR algorithm was applied. In addition, the physical diameter of the stainless steel rod was over-estimated by the MAR algorithm by 0.9 mm. Conclusion: This work indicates with the presence of metal in CT scans, the MAR algorithm is capable of providing a more accurate CT number without compromising the overall image quality. Future work will include the dosimetric impact on the MAR algorithm.« less

WE-EF-207-09: Single-Scan Dual-Energy CT Using Primary Modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrongolo, M; Zhu, L

Purpose: Compared with conventional CT, dual energy CT (DECT) provides better material differentiation but requires projection data with two different effective x-ray spectra. Current DECT scanners use either a two-scan setting or costly imaging components, which are not feasible or available on open-gantry cone-beam CT systems. We propose a hardware-based method which utilizes primary modulation to enable single-scan DECT on a conventional CT scanner. The CT imaging geometry of primary modulation is identical to that used in our previous method for scatter removal, making it possible for future combination with effective scatter correction on the same CT scanner. Methods: Wemore » insert an attenuation sheet with a spatially-varying pattern - primary modulator-between the x-ray source and the imaged object. During the CT scan, the modulator selectively hardens the x-ray beam at specific detector locations. Thus, the proposed method simultaneously acquires high and low energy data. High and low energy CT images are then reconstructed from projections with missing data via an iterative CT reconstruction algorithm with gradient weighting. Proof-of-concept studies are performed using a copper modulator on a cone-beam CT system. Results: Our preliminary results on the Catphan(c) 600 phantom indicate that the proposed method for single-scan DECT is able to successfully generate high-quality high and low energy CT images and distinguish different materials through basis material decomposition. By applying correction algorithms and using all of the acquired projection data, we can reconstruct a single CT image of comparable image quality to conventional CT images, i.e., without primary modulation. Conclusion: This work shows great promise in using a primary modulator to perform high-quality single-scan DECT imaging. Future studies will test method performance on anthropomorphic phantoms and perform quantitative analyses on image qualities and DECT decomposition accuracy. We will use simulations to optimize the modulator material and geometry parameters.« less

Investigating different computed tomography techniques for internal target volume definition.

PubMed

Yoganathan, S A; Maria Das, K J; Subramanian, V Siva; Raj, D Gowtham; Agarwal, Arpita; Kumar, Shaleen

2017-01-01

The aim of this work was to evaluate the various computed tomography (CT) techniques such as fast CT, slow CT, breath-hold (BH) CT, full-fan cone beam CT (FF-CBCT), half-fan CBCT (HF-CBCT), and average CT for delineation of internal target volume (ITV). In addition, these ITVs were compared against four-dimensional CT (4DCT) ITVs. Three-dimensional target motion was simulated using dynamic thorax phantom with target insert of diameter 3 cm for ten respiration data. CT images were acquired using a commercially available multislice CT scanner, and the CBCT images were acquired using On-Board-Imager. Average CT was generated by averaging 10 phases of 4DCT. ITVs were delineated for each CT by contouring the volume of the target ball; 4DCT ITVs were generated by merging all 10 phases target volumes. Incase of BH-CT, ITV was derived by boolean of CT phases 0%, 50%, and fast CT target volumes. ITVs determined by all CT and CBCT scans were significantly smaller (P < 0.05) than the 4DCT ITV, whereas there was no significant difference between average CT and 4DCT ITVs (P = 0.17). Fast CT had the maximum deviation (-46.1% ± 20.9%) followed by slow CT (-34.3% ± 11.0%) and FF-CBCT scans (-26.3% ± 8.7%). However, HF-CBCT scans (-12.9% ± 4.4%) and BH-CT scans (-11.1% ± 8.5%) resulted in almost similar deviation. On the contrary, average CT had the least deviation (-4.7% ± 9.8%). When comparing with 4DCT, all the CT techniques underestimated ITV. In the absence of 4DCT, the HF-CBCT target volumes with appropriate margin may be a reasonable approach for defining the ITV.

Frequencies of micronucleated reticulocytes, a dosimeter of DNA double-strand breaks, in infants receiving computed tomography or cardiac catheterization.

PubMed

Khattab, Mona; Walker, Dale M; Albertini, Richard J; Nicklas, Janice A; Lundblad, Lennart K A; Vacek, Pamela M; Walker, Vernon E

2017-08-01

The use of computed tomography (CT scans) has increased dramatically in recent decades, raising questions about the long-term safety of CT-emitted x-rays especially in infants who are more sensitive to radiation-induced effects. Cancer risk estimates for CT scans typically are extrapolated from models; therefore, new approaches measuring actual DNA damage are needed for improved estimations. Hence, changes in a dosimeter of DNA double-strand breaks, micronucleated reticulocytes (MN-RETs) measured by flow cytometry, were investigated in mice and infants exposed to CT scans. In male C57BL/6N mice (6-8 weeks-of-age), there was a dose-related increase in MN-RETs in blood samples collected 48h after CT scans delivering targeted exposures of 1-130 cGy x-rays (n=5-10/group, r=0.994, p=0.01), with significant increases occurring at exposure levels as low as 0.83 cGy x-rays compared to control mice (p=0.002). In paired blood specimens from infants with no history of a prior CT scan, there was no difference in MN-RET frequencies found 2h before (mean, 0.10±0.07%) versus 48h after (mean, 0.11±0.05%) a scheduled CT scan/cardiac catheterization. However, in infants having prior CT scan(s), MN-RET frequencies measured at 48h after a scheduled CT scan (mean=0.22±0.12%) were significantly higher than paired baseline values (mean, 0.17±0.07%; p=0.032). Increases in baseline (r=0.722, p<0.001) and 48-h post exposure (r=0.682, p<0.001) levels of MN-RETs in infants with a history of prior CT scans were significantly correlated with the number of previous CT scans. These preliminary findings suggest that prior CT scans increase the cellular responses to subsequent CT exposures. Thus, further investigation is needed to characterize the potential cancer risk from single versus repeated CT scans or cardiac catheterizations in infants. Copyright © 2017 Elsevier B.V. All rights reserved.

The use of a fully integrated electronic medical record to minimize cumulative lifetime radiation exposure from CT scanning to detect urinary tract calculi.

PubMed

Kohler, Steven W; Chen, Richard; Kagan, Alex; Helvey, Dustin W; Buccigrossi, David

2013-06-01

In order to determine the effects of implementation of an electronic medical record on rates of repeat computed tomography (CT) scanning in the emergency department (ED) setting, we analyzed the utilization of CT of the kidneys, ureters, and bladder (CT KUB) for the detection of urinary tract calculi for periods before and after the implementation of a hospital-wide electronic medical record system. Rates of repeat CT scanning within a 6-month period of previous scan were determined pre- and post-implementation and compared. Prior to implementation, there was a 6-month repeat rate of 6.2 % compared with the post-implementation period, which was associated with a 6-month repeat rate of 4.1 %. Statistical analysis using a two-sample, one-tailed t test for difference of means was associated with a p value of 0.00007. This indicates that the implementation of the electronic medical record system was associated with a 34 % decrease in 6-month repeat CT KUB scans. We conclude that the use of an electronic medical record can be associated with a decrease in utilization of unnecessary repeat CT imaging, leading to decreased cumulative lifetime risk for cancer in these patients and more efficient utilization of ED and radiologic resources.

Image quality of conventional images of dual-layer SPECTRAL CT: A phantom study.

PubMed

van Ommen, Fasco; Bennink, Edwin; Vlassenbroek, Alain; Dankbaar, Jan Willem; Schilham, Arnold M R; Viergever, Max A; de Jong, Hugo W A M

2018-05-10

Spectral CT using a dual layer detector offers the possibility of retrospectively introducing spectral information to conventional CT images. In theory, the dual-layer technology should not come with a dose or image quality penalty for conventional images. In this study, we evaluate the influence of a dual-layer detector (IQon Spectral CT, Philips Healthcare) on the image quality of conventional CT images, by comparing these images with those of a conventional but otherwise technically comparable single-layer CT scanner (Brilliance iCT, Philips Healthcare), by means of phantom experiments. For both CT scanners, conventional CT images were acquired using four adult scanning protocols: (a) body helical, (b) body axial, (c) head helical, and (d) head axial. A CATPHAN 600 phantom was scanned to conduct an assessment of image quality metrics at equivalent (CTDI) dose levels. Noise was characterized by means of noise power spectra (NPS) and standard deviation (SD) of a uniform region, and spatial resolution was evaluated with modulation transfer functions (MTF) of a tungsten wire. In addition, contrast-to-noise ratio (CNR), image uniformity, CT number linearity, slice thickness, slice spacing, and spatial linearity were measured and evaluated. Additional measurements of CNR, resolution and noise were performed in two larger phantoms. The resolution levels at 50%, 10%, and 5% MTF of the iCT and IQon showed small, but significant differences up to 0.25 lp/cm for body scans, and up to 0.2 lp/cm for head scans in favor of the IQon. The iCT and IQon showed perfect CT linearity for body scans, but for head scans both scanners showed an underestimation of the CT numbers of materials with a high opacity. Slice thickness was slightly overestimated for both scanners. Slice spacing was comparable and reconstructed correctly. In addition, spatial linearity was excellent for both scanners, with a maximum error of 0.11 mm. CNR was higher on the IQon compared to the iCT for both normal and larger phantoms with differences up to 0.51. Spatial resolution did not change with phantom size, but noise levels increased significantly. For head scans, IQon had a noise level that was significantly lower than the iCT, on the other hand IQon showed noise levels significantly higher than the iCT for body scans. Still, these differences were well within the specified range of performance of iCT scanners. At equivalent dose levels, this study showed similar quality of conventional images acquired on iCT and IQon for medium-sized phantoms and slightly degraded image quality for (very) large phantoms at lower tube voltages on the IQon. Accordingly, it may be concluded that the introduction of a dual-layer detector neither compromises image quality of conventional images nor increases radiation dose for normal-sized patients, and slightly degrades dose efficiency for large patients at 120 kVp and lower tube voltages. © 2018 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

The cost-effectiveness of diagnostic management strategies for adults with minor head injury.

PubMed

Holmes, M W; Goodacre, S; Stevenson, M D; Pandor, A; Pickering, A

2012-09-01

To estimate the cost-effectiveness of diagnostic management strategies for adults with minor head injury. A mathematical model was constructed to evaluate the incremental costs and effectiveness (Quality Adjusted Life years Gained, QALYs) of ten diagnostic management strategies for adults with minor head injuries. Secondary analyses were undertaken to determine the cost-effectiveness of hospital admission compared to discharge home and to explore the cost-effectiveness of strategies when no responsible adult was available to observe the patient after discharge. The apparent optimal strategy was based on the high and medium risk Canadian CT Head Rule (CCHRhm), although the costs and outcomes associated with each strategy were broadly similar. Hospital admission for patients with non-neurosurgical injury on CT dominated discharge home, whilst hospital admission for clinically normal patients with a normal CT was not cost-effective compared to discharge home with or without a responsible adult at £39 and £2.5 million per QALY, respectively. A selective CT strategy with discharge home if the CT scan was normal remained optimal compared to not investigating or CT scanning all patients when there was no responsible adult available to observe them after discharge. Our economic analysis confirms that the recent extension of access to CT scanning for minor head injury is appropriate. Liberal use of CT scanning based on a high sensitivity decision rule is not only effective but also cost-saving. The cost of CT scanning is very small compared to the estimated cost of caring for patients with brain injury worsened by delayed treatment. It is recommended therefore that all hospitals receiving patients with minor head injury should have unrestricted access to CT scanning for use in conjunction with evidence based guidelines. Provisionally the CCHRhm decision rule appears to be the best strategy although there is considerable uncertainty around the optimal decision rule. However, the CCHRhm rule appears to be the most widely validated and it therefore seems appropriate to conclude that the CCHRhm rule has the best evidence to support its use. Copyright © 2011 Elsevier Ltd. All rights reserved.

Value of repeat CT scans in low back pain and radiculopathy.

PubMed

Schroeder, Josh E; Barzilay, Yair; Kaplan, Leon; Itshayek, Eyal; Hiller, Nurith

2016-02-01

We assessed the clinical value of repeat spine CT scan in 108 patients aged 18-60 years who underwent repeat lumbar spine CT scan for low back pain or radiculopathy from January 2008 to December 2010. Patients with a neoplasm or symptoms suggesting underlying disease were excluded from the study. Clinical data was retrospectively reviewed. Index examinations and repeat CT scan performed at a mean of 24.3 ± 11.3 months later were compared by a senior musculoskeletal radiologist. Disc abnormalities (herniation, sequestration, bulge), spinal stenosis, disc space narrowing, and bony changes (osteophytes, fractures, other changes) were documented. Indications for CT scan were low back pain (60 patients, 55%), radiculopathy (46 patients, 43%), or nonspecific back pain (two patients, 2%). A total of 292 spine pathologies were identified in 98 patients (90.7%); in 10 patients (9.3%) no spine pathology was seen on index or repeat CT scan. At repeat CT scan, 269/292 pathologies were unchanged (92.1%); 10/292 improved (3.4%), 8/292 worsened (2.8%, disc herniation or spinal stenosis), and five new pathologies were identified. No substantial therapeutic change was required in patients with worsened or new pathology. Added diagnostic value from repeat CT scan performed within 2-3 years was rare in patients suffering chronic or recurrent low back pain or radiculopathy, suggesting that repeat CT scan should be considered only in patients with progressive neurologic deficits, new neurologic complaints, or signs implying serious underlying conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reconstruction of a time-averaged midposition CT scan for radiotherapy planning of lung cancer patients using deformable registration.

PubMed

Wolthaus, J W H; Sonke, J J; van Herk, M; Damen, E M F

2008-09-01

lower lobe lung tumors move with amplitudes of up to 2 cm due to respiration. To reduce respiration imaging artifacts in planning CT scans, 4D imaging techniques are used. Currently, we use a single (midventilation) frame of the 4D data set for clinical delineation of structures and radiotherapy planning. A single frame, however, often contains artifacts due to breathing irregularities, and is noisier than a conventional CT scan since the exposure per frame is lower. Moreover, the tumor may be displaced from the mean tumor position due to hysteresis. The aim of this work is to develop a framework for the acquisition of a good quality scan representing all scanned anatomy in the mean position by averaging transformed (deformed) CT frames, i.e., canceling out motion. A nonrigid registration method is necessary since motion varies over the lung. 4D and inspiration breath-hold (BH) CT scans were acquired for 13 patients. An iterative multiscale motion estimation technique was applied to the 4D CT scan, similar to optical flow but using image phase (gray-value transitions from bright to dark and vice versa) instead. From the (4D) deformation vector field (DVF) derived, the local mean position in the respiratory cycle was computed and the 4D DVF was modified to deform all structures of the original 4D CT scan to this mean position. A 3D midposition (MidP) CT scan was then obtained by (arithmetic or median) averaging of the deformed 4D CT scan. Image registration accuracy, tumor shape deviation with respect to the BH CT scan, and noise were determined to evaluate the image fidelity of the MidP CT scan and the performance of the technique. Accuracy of the used deformable image registration method was comparable to established automated locally rigid registration and to manual landmark registration (average difference to both methods < 0.5 mm for all directions) for the tumor region. From visual assessment, the registration was good for the clearly visible features (e.g., tumor and diaphragm). The shape of the tumor, with respect to that of the BH CT scan, was better represented by the MidP reconstructions than any of the 4D CT frames (including MidV; reduction of "shape differences" was 66%). The MidP scans contained about one-third the noise of individual 4D CT scan frames. We implemented an accurate method to estimate the motion of structures in a 4D CT scan. Subsequently, a novel method to create a midposition CT scan (time-weighted average of the anatomy) for treatment planning with reduced noise and artifacts was introduced. Tumor shape and position in the MidP CT scan represents that of the BH CT scan better than MidV CT scan and, therefore, was found to be appropriate for treatment planning.

Assessment of the effects of CT dose in averaged x-ray CT images of a dose-sensitive polymer gel

NASA Astrophysics Data System (ADS)

Kairn, T.; Kakakhel, M. B.; Johnston, H.; Jirasek, A.; Trapp, J. V.

2015-01-01

The signal-to-noise ratio achievable in x-ray computed tomography (CT) images of polymer gels can be increased by averaging over multiple scans of each sample. However, repeated scanning delivers a small additional dose to the gel which may compromise the accuracy of the dose measurement. In this study, a NIPAM-based polymer gel was irradiated and then CT scanned 25 times, with the resulting data used to derive an averaged image and a "zero-scan" image of the gel. Comparison between these two results and the first scan of the gel showed that the averaged and zero-scan images provided better contrast, higher contrast-to- noise and higher signal-to-noise than the initial scan. The pixel values (Hounsfield units, HU) in the averaged image were not noticeably elevated, compared to the zero-scan result and the gradients used in the linear extrapolation of the zero-scan images were small and symmetrically distributed around zero. These results indicate that the averaged image was not artificially lightened by the small, additional dose delivered during CT scanning. This work demonstrates the broader usefulness of the zero-scan method as a means to verify the dosimetric accuracy of gel images derived from averaged x-ray CT data.

Computed tomography scan to detect traumatic arthrotomies and identify periarticular wounds not requiring surgical intervention: an improvement over the saline load test.

PubMed

Konda, Sanjit R; Davidovitch, Roy I; Egol, Kenneth A

2013-09-01

To report our experience with computed tomography (CT) scans to detect traumatic arthrotomies of the knee (TAK) joint based on the presence of intra-articular air. Retrospective review. Level I trauma center. Sixty-two consecutive patients (63 knees) underwent a CT scan of the knee in the emergency department and had a minimum of 14 days follow-up. Cohort of 37 patients (37 knees) from the original 62 patients who underwent a saline load test (SLT). CT scan and SLT. Positive traumatic arthrotomy of the knee (+TAK) was defined as operating room (OR) confirmation of an arthrotomy or no intra-articular air on CT scan (-iaCT) (and -SLT if performed) with follow-up revealing a septic knee. Periarticular wound equivalent to no traumatic arthrotomy (pw = (-TAK)) was defined as OR evaluation revealing no arthrotomy or -iaCT (and -SLT if performed) with follow-up revealing no septic knee. All 32 knees with intra-articular air on CT scan (+iaCT) had OR confirmation of a TAK and none of these patients had a knee infection at a mean follow-up of 140.0 ± 279.6 days. None of the 31 patients with -iaCT had a knee infection at a mean follow-up of 291.0 ± 548.1 days. Based on these results, the sensitivity and specificity of the CT scan to detect +TAK and pw = (-TAK) was 100%. In a subgroup of 37 patients that received both a CT scan and the conventional SLT, the sensitivity and specificity of the CT scan was 100% compared with 92% for the SLT (P < 0.001). CT scan performs better than the conventional SLT to detect traumatic knee arthrotomies and identify periarticular knee wounds that do not require surgical intervention and should be considered a valid diagnostic test in the appropriate clinical setting. Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

With "big data" comes big responsibility: outreach to North Carolina Medicaid patients with 10 or more computed tomography scans in 12 months.

PubMed

Biola, Holly; Best, Randall M; Lahlou, Rita M; Burke, Lauren M; Dewar, Charles; Jackson, Carlos T; Broder, Joshua; Grey, Linda; Semelka, Richard C; Dobson, Allen

2014-01-01

Patients are being exposed to increasing levels of ionizing radiation, much of it from computed tomography (CT) scans. Adults without a cancer diagnosis who received 10 or more CT scans in 2010 were identified from North Carolina Medicaid claims data and were sent a letter in July 2011 informing them of their radiation exposure; those who had undergone 20 or more CT scans in 2010 were also telephoned. The CT scan exposure of these high-exposure patients during the 12 months following these interventions was compared with that of adult Medicaid patients without cancer who had at least 1 CT scan but were not in the intervention population. The average number of CT scans per month for the high-exposure population decreased over time, but most of that reduction occurred 6-9 months before our interventions took place. At about the same time, the number of CT scans per month also decreased in adult Medicaid patients without cancer who had at least 1 CT scan but were not in the intervention population. Our data do not include information about CT scans that may have been performed during times when patients were not covered by Medicaid. Some of our letters may not have been received or understood. Some high-exposure patients were unintentionally excluded from our study because organization of data on Medicaid claims varies by setting of care. Our patient education intervention was not temporally associated with significant decreases in subsequent CT exposure. Effecting behavior change to reduce exposure to ionizing radiation requires more than an educational letter or telephone call.

18F-FDG uptake and its clinical relevance in primary gastric lymphoma.

PubMed

Yi, Jun Ho; Kim, Seok Jin; Choi, Joon Young; Ko, Young Hyeh; Kim, Byung-Tae; Kim, Won Seog

2010-06-01

We studied the clinical relevance of (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in patients with primary gastric lymphoma underwent positron emission tomography (PET)/ computed tomography (CT) scan. Forty-two patients with primary gastric lymphoma were analysed: 32 diffuse large B-cell lymphomas (DLBCL) and 10 extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT lymphomas). The PET/CT scans were compared with clinical and pathologic features, and the results of CT and endoscopy. Nine patients were up-staged based on the results of their PET/CT scan compared to CT (seven DLBCLs, two MALT lymphomas) while six patients were down-staged by the PET/CT scan. The standard uptake value (SUV) was used as an indicator of a lesion with a high metabolic rate. The high SUVmax group, defined as an SUVmax >or= median value, was significantly associated with an advanced Lugano stage (p < 0.001). Three patients with DLBCL, who showed an initially high SUVmax, died of disease progression. Among 24 patients for whom follow-up PET/CT scan with endoscopy was performed, 11 patients with ulcerative or mucosal lesions showed residual (18)F-FDG uptake. All of these gastric lesions were grossly and pathologically benign lesions without evidence of lymphoma cells. In conclusion, PET/CT scan can be used in staging patients with primary gastric lymphoma; however, the residual (18)F-FDG uptake observed during follow-up should be interpreted cautiously and should be combined with endoscopy and multiple biopsies of the stomach. (c) 2009 John Wiley & Sons, Ltd.

A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty

PubMed Central

2014-01-01

Background and purpose It is difficult to evaluate glenoid component periprosthetic radiolucencies in total shoulder arthroplasties (TSAs) using plain radiographs. This study was performed to evaluate whether computed tomography (CT) using a specific patient position in the CT scanner provides a better method for assessing radiolucencies in TSA. Methods Following TSA, 11 patients were CT scanned in a lateral decubitus position with maximum forward flexion, which aligns the glenoid orientation with the axis of the CT scanner. Follow-up CT scanning is part of our routine patient care. Glenoid component periprosthetic lucency was assessed according to the Molé score and it was compared to routine plain radiographs by 5 observers. Results The protocol almost completely eliminated metal artifacts in the CT images and allowed accurate assessment of periprosthetic lucency of the glenoid fixation. Positioning of the patient within the CT scanner as described was possible for all 11 patients. A radiolucent line was identified in 54 of the 55 observed CT scans and osteolysis was identified in 25 observations. The average radiolucent line Molé score was 3.4 (SD 2.7) points with plain radiographs and 9.5 (SD 0.8) points with CT scans (p = 0.001). The mean intra-observer variance was lower in the CT scan group than in the plain radiograph group (p = 0.001). Interpretation The CT scan protocol we used is of clinical value in routine assessment of glenoid periprosthetic lucency after TSA. The technique improves the ability to detect and monitor radiolucent lines and, therefore, possibly implant loosening also. PMID:24286563

The effect of sagittal rotation of the glenoid on axial glenoid width and glenoid version in computed tomography scan imaging.

PubMed

Gross, Daniel J; Golijanin, Petar; Dumont, Guillaume D; Parada, Stephen A; Vopat, Bryan G; Reinert, Steven E; Romeo, Anthony A; Provencher, C D R Matthew T

2016-01-01

Computed tomography (CT) scans of the shoulder are often not well aligned to the axis of the scapula and glenoid. The purpose of this paper was to determine the effect of sagittal rotation of the glenoid on axial measurements of anterior-posterior (AP) glenoid width and glenoid version attained by standard CT scan. In addition, we sought to define the angle of rotation required to correct the CT scan to optimal positioning. A total of 30 CT scans of the shoulder were reformatted using OsiriX software multiplanar reconstruction. The uncorrected (UNCORR) and corrected (CORR) CT scans were compared for measurements of both (1) axial AP glenoid width and (2) glenoid version at 5 standardized axial cuts. The mean difference in glenoid version was 2.6% (2° ± 0.1°; P = .0222) and the mean difference in AP glenoid width was 5.2% (1.2 ± 0.42 mm; P = .0026) in comparing the CORR and UNCORR scans. The mean angle of correction required to align the sagittal plane was 20.1° of rotation (range, 9°-39°; standard error of mean, 1.2°). These findings demonstrate that UNCORR CT scans of the glenohumeral joint do not correct for the sagittal rotation of the glenoid, and this affects the characteristics of the axial images. Failure to align the sagittal image to the 12-o'clock to 6-o'clock axis results in measurement error in both glenoid version and AP glenoid width. Use of UNCORR CT images may have notable implications for decision-making and surgical treatment. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Evaluation of the use of automatic exposure control and automatic tube potential selection in low-dose cerebrospinal fluid shunt head CT.

PubMed

Wallace, Adam N; Vyhmeister, Ross; Bagade, Swapnil; Chatterjee, Arindam; Hicks, Brandon; Ramirez-Giraldo, Juan Carlos; McKinstry, Robert C

2015-06-01

Cerebrospinal fluid shunts are primarily used for the treatment of hydrocephalus. Shunt complications may necessitate multiple non-contrast head CT scans resulting in potentially high levels of radiation dose starting at an early age. A new head CT protocol using automatic exposure control and automated tube potential selection has been implemented at our institution to reduce radiation exposure. The purpose of this study was to evaluate the reduction in radiation dose achieved by this protocol compared with a protocol with fixed parameters. A retrospective sample of 60 non-contrast head CT scans assessing for cerebrospinal fluid shunt malfunction was identified, 30 of which were performed with each protocol. The radiation doses of the two protocols were compared using the volume CT dose index and dose length product. The diagnostic acceptability and quality of each scan were evaluated by three independent readers. The new protocol lowered the average volume CT dose index from 15.2 to 9.2 mGy representing a 39 % reduction (P < 0.01; 95 % CI 35-44 %) and lowered the dose length product from 259.5 to 151.2 mGy/cm representing a 42 % reduction (P < 0.01; 95 % CI 34-50 %). The new protocol produced diagnostically acceptable scans with comparable image quality to the fixed parameter protocol. A pediatric shunt non-contrast head CT protocol using automatic exposure control and automated tube potential selection reduced patient radiation dose compared with a fixed parameter protocol while producing diagnostic images of comparable quality.

The scab-like sign: A CT finding indicative of haemoptysis in patients with chronic pulmonary aspergillosis?

PubMed

Sato, Haruka; Okada, Fumito; Matsumoto, Shunro; Mori, Hiromu; Kashiwagi, Junji; Komatsu, Eiji; Maeda, Toru; Nishida, Haruto; Daa, Tsutomu; Ohtani, Satoshi; Umeki, Kenji; Ando, Masaru; Kadota, Junichi

2018-05-03

The aim of this study was to assess the CT findings that characterise haemoptysis in patients with chronic pulmonary aspergillosis (CPA). We retrospectively identified 120 consecutive patients with CPA (84 men and 36 women, 17-89 years of age, mean age 68.4 years) who had undergone a total of 829 CT examinations between January 2007 and February 2017. In the 11 patients who underwent surgical resection, CT images were compared with the pathological results. The scab-like sign was seen on 142 of the 829 CT scans, specifically, in 87 of the 90 CT scans for haemoptysis and in 55 of the 739 CT scans obtained during therapy evaluation. In 48 of those 55 patients, haemoptysis occurred within 55 days (mean 12.0 days) after the CT scan. In the 687 CT scans with no scab-like sign, there were only three instances of subsequent haemoptysis in the respective patients over the following 6 months. Patients with and without scab-like sign differed significantly in the frequency of haemoptysis occurring after a CT scan (p<0.0001). Pathologically, the scab-like sign corresponded to a fibrinopurulent mass or blood crust. The scab-like sign should be considered as a CT finding indicative of haemoptysis. • Haemoptysis is commonly found in patients with CPA. • A CT finding indicative of haemoptysis in CPA patients is described. • Scab-like sign may identify CPA patients at higher risk of haemoptysis.

The value of FDG PET/CT for follow-up of patients with melanoma: a retrospective analysis

PubMed Central

Vensby, Philip H; Schmidt, Grethe; Kjær, Andreas; Fischer, Barbara M

2017-01-01

The incidence of melanoma (MM) is among the fastest rising cancers in the western countries. Positron Emission Tomography with Computed Tomography (PET/CT) is a valuable non-invasive tool for the diagnosis and staging of patients with MM. However, research on the value of PET/CT in follow-up of melanoma patients is limited. This study assesses the diagnostic value of PET/CT for follow-up after melanoma surgery. This retrospective study includes patients with MM who performed at least one PET/CT scan after initial surgery and staging. PET/CT findings were compared to histology, MRI or fine needle aspiration (FNA) to estimate the diagnostic accuracy. The diagnostic performance of PET/CT performed in patients with and without a clinical suspicion of relapse was compared. 238 patients (526 scans) were included. Of the 526 scans 130 (25%) scans were PET-positive, 365 (69%) PET-negative, and 28 (5%) had equivocal findings. Sensitivity was 89% [0.82-0.94], specificity 92% [0.89-0.95], positive and negative predictive values of 78% [0.70-0.84] and 97% [0.94-0.98] respectively. When stratified for reason of referral there was no statistical significant difference in the diagnostic accuracy of PET/CT between patients referred with or without a clinical suspicion of relapse. This study demonstrates that PET/CT despite a moderate sensitivity has a high negative predictive value in the follow-up of melanoma patients. Thus, a negative PET/CT-scan essentially rules out relapse. However, the frequency of false positive findings is relatively high, especially among patients undergoing a “routine” PET/CT with no clinical suspicion of relapse, potentially causing anxiety and leading to further diagnostic procedures. PMID:29348980

The value of FDG PET/CT for follow-up of patients with melanoma: a retrospective analysis.

PubMed

Vensby, Philip H; Schmidt, Grethe; Kjær, Andreas; Fischer, Barbara M

2017-01-01

The incidence of melanoma (MM) is among the fastest rising cancers in the western countries. Positron Emission Tomography with Computed Tomography (PET/CT) is a valuable non-invasive tool for the diagnosis and staging of patients with MM. However, research on the value of PET/CT in follow-up of melanoma patients is limited. This study assesses the diagnostic value of PET/CT for follow-up after melanoma surgery. This retrospective study includes patients with MM who performed at least one PET/CT scan after initial surgery and staging. PET/CT findings were compared to histology, MRI or fine needle aspiration (FNA) to estimate the diagnostic accuracy. The diagnostic performance of PET/CT performed in patients with and without a clinical suspicion of relapse was compared. 238 patients (526 scans) were included. Of the 526 scans 130 (25%) scans were PET-positive, 365 (69%) PET-negative, and 28 (5%) had equivocal findings. Sensitivity was 89% [0.82-0.94], specificity 92% [0.89-0.95], positive and negative predictive values of 78% [0.70-0.84] and 97% [0.94-0.98] respectively. When stratified for reason of referral there was no statistical significant difference in the diagnostic accuracy of PET/CT between patients referred with or without a clinical suspicion of relapse. This study demonstrates that PET/CT despite a moderate sensitivity has a high negative predictive value in the follow-up of melanoma patients. Thus, a negative PET/CT-scan essentially rules out relapse. However, the frequency of false positive findings is relatively high, especially among patients undergoing a "routine" PET/CT with no clinical suspicion of relapse, potentially causing anxiety and leading to further diagnostic procedures.

Hyoid bone development: An assessment of optimal CT scanner parameters and 3D volume rendering techniques

PubMed Central

Cotter, Meghan M.; Whyms, Brian J.; Kelly, Michael P.; Doherty, Benjamin M.; Gentry, Lindell R.; Bersu, Edward T.; Vorperian, Houri K.

2015-01-01

The hyoid bone anchors and supports the vocal tract. Its complex shape is best studied in three dimensions, but it is difficult to capture on computed tomography (CT) images and three-dimensional volume renderings. The goal of this study was to determine the optimal CT scanning and rendering parameters to accurately measure the growth and developmental anatomy of the hyoid and to determine whether it is feasible and necessary to use these parameters in the measurement of hyoids from in vivo CT scans. Direct linear and volumetric measurements of skeletonized hyoid bone specimens were compared to corresponding CT images to determine the most accurate scanning parameters and three-dimensional rendering techniques. A pilot study was undertaken using in vivo scans from a retrospective CT database to determine feasibility of quantifying hyoid growth. Scanning parameters and rendering technique affected accuracy of measurements. Most linear CT measurements were within 10% of direct measurements; however, volume was overestimated when CT scans were acquired with a slice thickness greater than 1.25 mm. Slice-by-slice thresholding of hyoid images decreased volume overestimation. The pilot study revealed that the linear measurements tested correlate with age. A fine-tuned rendering approach applied to small slice thickness CT scans produces the most accurate measurements of hyoid bones. However, linear measurements can be accurately assessed from in vivo CT scans at a larger slice thickness. Such findings imply that investigation into the growth and development of the hyoid bone, and the vocal tract as a whole, can now be performed using these techniques. PMID:25810349

Hyoid Bone Development: An Assessment Of Optimal CT Scanner Parameters and Three-Dimensional Volume Rendering Techniques.

PubMed

Cotter, Meghan M; Whyms, Brian J; Kelly, Michael P; Doherty, Benjamin M; Gentry, Lindell R; Bersu, Edward T; Vorperian, Houri K

2015-08-01

The hyoid bone anchors and supports the vocal tract. Its complex shape is best studied in three dimensions, but it is difficult to capture on computed tomography (CT) images and three-dimensional volume renderings. The goal of this study was to determine the optimal CT scanning and rendering parameters to accurately measure the growth and developmental anatomy of the hyoid and to determine whether it is feasible and necessary to use these parameters in the measurement of hyoids from in vivo CT scans. Direct linear and volumetric measurements of skeletonized hyoid bone specimens were compared with corresponding CT images to determine the most accurate scanning parameters and three-dimensional rendering techniques. A pilot study was undertaken using in vivo scans from a retrospective CT database to determine feasibility of quantifying hyoid growth. Scanning parameters and rendering technique affected accuracy of measurements. Most linear CT measurements were within 10% of direct measurements; however, volume was overestimated when CT scans were acquired with a slice thickness greater than 1.25 mm. Slice-by-slice thresholding of hyoid images decreased volume overestimation. The pilot study revealed that the linear measurements tested correlate with age. A fine-tuned rendering approach applied to small slice thickness CT scans produces the most accurate measurements of hyoid bones. However, linear measurements can be accurately assessed from in vivo CT scans at a larger slice thickness. Such findings imply that investigation into the growth and development of the hyoid bone, and the vocal tract as a whole, can now be performed using these techniques. © 2015 Wiley Periodicals, Inc.

Comparison of helical and cine acquisitions for 4D-CT imaging with multislice CT.

PubMed

Pan, Tinsu

2005-02-01

We proposed a data sufficiency condition (DSC) for four-dimensional-CT (4D-CT) imaging on a multislice CT scanner, designed a pitch factor for a helical 4D-CT, and compared the acquisition time, slice sensitivity profile (SSP), effective dose, ability to cope with an irregular breathing cycle, and gating technique (retrospective or prospective) of the helical 4D-CT and the cine 4D-CT on the General Electric (GE) LightSpeed RT (4-slice), Plus (4-slice), Ultra (8-slice) and 16 (16-slice) multislice CT scanners. To satisfy the DSC, a helical or cine 4D-CT acquisition has to collect data at each location for the duration of a breathing cycle plus the duration of data acquisition for an image reconstruction. The conditions for the comparison were 20 cm coverage in the cranial-caudal direction, a 4 s breathing cycle, and half-scan reconstruction. We found that the helical 4D-CT has the advantage of a shorter scan time that is 10% shorter than that of the cine 4D-CT, and the disadvantages of 1.8 times broadening of SSP and requires an additional breathing cycle of scanning to ensure an adequate sampling at the start and end locations. The cine 4D-CT has the advantages of maintaining the same SSP as slice collimation (e.g., 8 x 2.5 mm slice collimation generates 2.5 mm SSP in the cine 4D-CT as opposed to 4.5 mm in the helical 4D-CT) and a lower dose by 4% on the 8- and 16-slice systems, and 8% on the 4-slice system. The advantage of faster scanning in the helical 4D-CT will diminish if a repeat scan at the location of a breathing irregularity becomes necessary. The cine 4D-CT performs better than the helical 4D-CT in the repeat scan because it can scan faster and is more dose efficient.

Dual energy micro CT SkyScan 1173 for the characterization of urinary stone

NASA Astrophysics Data System (ADS)

Fitri, L. A.; Asyana, V.; Ridwan, T.; Anwary, F.; Soekersi, H.; Latief, F. D. E.; Haryanto, F.

2016-03-01

Knowledge of the composition of urinary stones is an essential part to determine suitable treatments for patients. The aim of this research is to characterize the urinary stones by using dual energy micro CT SkyScan 11173. This technique combines high-energy and low- energy scanning during a single acquisition. Six human urinary stones were scanned in vitro using 80 kV and 120 kV micro CT SkyScan 1173. Projected images were produced by micro CT SkyScan 1173 and then reconstructed using NRecon (in-house software from SkyScan) to obtain a complete 3D image. The urinary stone images were analysed using CT analyser to obtain information of internal structure and Hounsfield Unit (HU) values to determine the information regarding the composition of the urinary stones, respectively. HU values obtained from some regions of interest in the same slice are compared to a reference HU. The analysis shows information of the composition of the six scanned stones obtained. The six stones consist of stone number 1 (calcium+cystine), number 2 (calcium+struvite), number 3 (calcium+cystine+struvite), number 4 (calcium), number 5 (calcium+cystine+struvite), and number 6 (calcium+uric acid). This shows that dual energy micro CT SkyScan 1173 was able to characterize the composition of the urinary stone.

Use of PET/CT instead of CT-only when planning for radiation therapy does not notably increase life years lost in children being treated for cancer.

PubMed

Kornerup, Josefine S; Brodin, Patrik; Birk Christensen, Charlotte; Björk-Eriksson, Thomas; Kiil-Berthelsen, Anne; Borgwardt, Lise; Munck Af Rosenschöld, Per

2015-04-01

PET/CT may be more helpful than CT alone for radiation therapy planning, but the added risk due to higher doses of ionizing radiation is unknown. To estimate the risk of cancer induction and mortality attributable to the [F-18]2-fluoro-2-deoxyglucose (FDG) PET and CT scans used for radiation therapy planning in children with cancer, and compare to the risks attributable to the cancer treatment. Organ doses and effective doses were estimated for 40 children (2-18 years old) who had been scanned using PET/CT as part of radiation therapy planning. The risk of inducing secondary cancer was estimated using the models in BEIR VII. The prognosis of an induced cancer was taken into account and the reduction in life expectancy, in terms of life years lost, was estimated for the diagnostics and compared to the life years lost attributable to the therapy. Multivariate linear regression was performed to find predictors for a high contribution to life years lost from the radiation therapy planning diagnostics. The mean contribution from PET to the effective dose from one PET/CT scan was 24% (range: 7-64%). The average proportion of life years lost attributable to the nuclear medicine dose component from one PET/CT scan was 15% (range: 3-41%). The ratio of life years lost from the radiation therapy planning PET/CT scans and that of the cancer treatment was on average 0.02 (range: 0.01-0.09). Female gender was associated with increased life years lost from the scans (P < 0.001). Using FDG-PET/CT instead of CT only when defining the target volumes for radiation therapy of children with cancer does not notably increase the number of life years lost attributable to diagnostic examinations.

Comparative effectiveness of using computed tomography alone to exclude cervical spine injuries in obtunded or intubated patients: meta-analysis of 14,327 patients with blunt trauma.

PubMed

Panczykowski, David M; Tomycz, Nestor D; Okonkwo, David O

2011-09-01

The current standard of practice for clearance of the cervical spine in obtunded patients suffering blunt trauma is to use CT and an adjuvant imaging modality (such as MR imaging). The objective of this study was to determine the comparative effectiveness of multislice helical CT alone to diagnose acute unstable cervical spine injury following blunt trauma. The authors performed a meta-analysis of studies comparing modern CT with adjunctive imaging modalities and required that studies present acute traumatic findings as well as treatment for unstable injuries. Study quality, population characteristics, diagnostic protocols, and outcome data were extracted. Positive disease status included all injuries necessitating surgical or orthotic stabilization identified on imaging and/or clinical follow-up. Seventeen studies encompassing 14,327 patients met the inclusion criteria. Overall, the sensitivity and specificity for modern CT were both > 99.9% (95% CI 0.99-1.00 and 0.99-1.00, respectively). The negative likelihood ratio of an unstable cervical injury after a CT scan negative for acute injury was < 0.001 (95% CI 0.00-0.01), while the negative predictive value of a normal CT scan was 100% (95% CI 0.96-1.00). Global severity of injury, CT slice thickness, and study quality did not significantly affect accuracy estimates. Modern CT alone is sufficient to detect unstable cervical spine injuries in trauma patients. Adjuvant imaging is unnecessary when the CT scan is negative for acute injury. Results of this meta-analysis strongly show that the cervical collar may be removed from obtunded or intubated trauma patients if a modern CT scan is negative for acute injury.

Immediate total-body CT scanning versus conventional imaging and selective CT scanning in patients with severe trauma (REACT-2): a randomised controlled trial.

PubMed

Sierink, Joanne C; Treskes, Kaij; Edwards, Michael J R; Beuker, Benn J A; den Hartog, Dennis; Hohmann, Joachim; Dijkgraaf, Marcel G W; Luitse, Jan S K; Beenen, Ludo F M; Hollmann, Markus W; Goslings, J Carel

2016-08-13

Published work suggests a survival benefit for patients with trauma who undergo total-body CT scanning during the initial trauma assessment; however, level 1 evidence is absent. We aimed to assess the effect of total-body CT scanning compared with the standard work-up on in-hospital mortality in patients with trauma. We undertook an international, multicentre, randomised controlled trial at four hospitals in the Netherlands and one in Switzerland. Patients aged 18 years or older with trauma with compromised vital parameters, clinical suspicion of life-threatening injuries, or severe injury were randomly assigned (1:1) by ALEA randomisation to immediate total-body CT scanning or to a standard work-up with conventional imaging supplemented with selective CT scanning. Neither doctors nor patients were masked to treatment allocation. The primary endpoint was in-hospital mortality, analysed in the intention-to-treat population and in subgroups of patients with polytrauma and those with traumatic brain injury. The χ(2) test was used to assess differences in mortality. This trial is registered with ClinicalTrials.gov, number NCT01523626. Between April 22, 2011, and Jan 1, 2014, 5475 patients were assessed for eligibility, 1403 of whom were randomly assigned: 702 to immediate total-body CT scanning and 701 to the standard work-up. 541 patients in the immediate total-body CT scanning group and 542 in the standard work-up group were included in the primary analysis. In-hospital mortality did not differ between groups (total-body CT 86 [16%] of 541 vs standard work-up 85 [16%] of 542; p=0.92). In-hospital mortality also did not differ between groups in subgroup analyses in patients with polytrauma (total-body CT 81 [22%] of 362 vs standard work-up 82 [25%] of 331; p=0.46) and traumatic brain injury (68 [38%] of 178 vs 66 [44%] of 151; p=0.31). Three serious adverse events were reported in patients in the total-body CT group (1%), one in the standard work-up group (<1%), and one in a patient who was excluded after random allocation. All five patients died. Diagnosing patients with an immediate total-body CT scan does not reduce in-hospital mortality compared with the standard radiological work-up. Because of the increased radiation dose, future research should focus on the selection of patients who will benefit from immediate total-body CT. ZonMw, the Netherlands Organisation for Health Research and Development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluating the effect of increased pitch, iterative reconstruction and dual source CT on dose reduction and image quality.

PubMed

Gariani, Joanna; Martin, Steve P; Botsikas, Diomidis; Becker, Christoph D; Montet, Xavier

2018-06-14

To compare radiation dose and image quality of thoracoabdominal scans obtained with a high-pitch protocol (pitch 3.2) and iterative reconstruction (Sinogram Affirmed Iterative Reconstruction) in comparison to standard pitch reconstructed with filtered back projection (FBP) using dual source CT. 114 CT scans (Somatom Definition Flash, Siemens Healthineers, Erlangen, Germany), 39 thoracic scans, 54 thoracoabdominal scans and 21 abdominal scans were performed. Analysis of three protocols was undertaken; pitch of 1 reconstructed with FBP, pitch of 3.2 reconstructed with SAFIRE, pitch of 3.2 with stellar detectors reconstructed with SAFIRE. Objective and subjective image analysis were performed. Dose differences of the protocols used were compared. Dose was reduced when comparing scans with a pitch of 1 reconstructed with FBP to high-pitch scans with a pitch of 3.2 reconstructed with SAFIRE with a reduction of volume CT dose index of 75% for thoracic scans, 64% for thoracoabdominal scans and 67% for abdominal scans. There was a further reduction after the implementation of stellar detectors reflected in a reduction of 36% of the dose-length product for thoracic scans. This was not at the detriment of image quality, contrast-to-noise ratio, signal-to-noise ratio and the qualitative image analysis revealed a superior image quality in the high-pitch protocols. The combination of a high pitch protocol with iterative reconstruction allows significant dose reduction in routine chest and abdominal scans whilst maintaining or improving diagnostic image quality, with a further reduction in thoracic scans with stellar detectors. Advances in knowledge: High pitch imaging with iterative reconstruction is a tool that can be used to reduce dose without sacrificing image quality.

Leukemia and brain tumors among children after radiation exposure from CT scans: design and methodological opportunities of the Dutch Pediatric CT Study.

PubMed

Meulepas, Johanna M; Ronckers, Cécile M; Smets, Anne M J B; Nievelstein, Rutger A J; Jahnen, Andreas; Lee, Choonsik; Kieft, Mariëtte; Laméris, Johan S; van Herk, Marcel; Greuter, Marcel J W; Jeukens, Cécile R L P N; van Straten, Marcel; Visser, Otto; van Leeuwen, Flora E; Hauptmann, Michael

2014-04-01

Computed tomography (CT) scans are indispensable in modern medicine; however, the spectacular rise in global use coupled with relatively high doses of ionizing radiation per examination have raised radiation protection concerns. Children are of particular concern because they are more sensitive to radiation-induced cancer compared with adults and have a long lifespan to express harmful effects which may offset clinical benefits of performing a scan. This paper describes the design and methodology of a nationwide study, the Dutch Pediatric CT Study, regarding risk of leukemia and brain tumors in children after radiation exposure from CT scans. It is a retrospective record-linkage cohort study with an expected number of 100,000 children who received at least one electronically archived CT scan covering the calendar period since the introduction of digital archiving until 2012. Information on all archived CT scans of these children will be obtained, including date of examination, scanned body part and radiologist's report, as well as the machine settings required for organ dose estimation. We will obtain cancer incidence by record linkage with external databases. In this article, we describe several approaches to the collection of data on archived CT scans, the estimation of radiation doses and the assessment of confounding. The proposed approaches provide useful strategies for data collection and confounder assessment for general retrospective record-linkage studies, particular those using hospital databases on radiological procedures for the assessment of exposure to ionizing or non-ionizing radiation.

Pulmonary Venous Anatomy Imaging with Low-Dose, Prospectively ECG-Triggered, High-Pitch 128-Slice Dual Source Computed Tomography

PubMed Central

Thai, Wai-ee; Wai, Bryan; Lin, Kaity; Cheng, Teresa; Heist, E. Kevin; Hoffmann, Udo; Singh, Jagmeet; Truong, Quynh A.

2012-01-01

Background Efforts to reduce radiation from cardiac computed tomography (CT) are essential. Using a prospectively triggered, high-pitch dual source CT (DSCT) protocol, we aim to determine the radiation dose and image quality (IQ) in patients undergoing pulmonary vein (PV) imaging. Methods and Results In 94 patients (61±9 years, 71% male) who underwent 128-slice DSCT (pitch 3.4), radiation dose and IQ were assessed and compared between 69 patients in sinus rhythm (SR) and 25 in atrial fibrillation (AF). Radiation dose was compared in a subset of 19 patients with prior retrospective or prospectively triggered CT PV scans without high-pitch. In a subset of 18 patients with prior magnetic resonance imaging (MRI) for PV assessment, PV anatomy and scan duration were compared to high-pitch CT. Using the high-pitch protocol, total effective radiation dose was 1.4 [1.3, 1.9] mSv, with no difference between SR and AF (1.4 vs 1.5 mSv, p=0.22). No high-pitch CT scans were non-diagnostic or had poor IQ. Radiation dose was reduced with high-pitch (1.6 mSv) compared to standard protocols (19.3 mSv, p<0.0001). This radiation dose reduction was seen with SR (1.5 vs 16.7 mSv, p<0.0001) but was more profound with AF (1.9 vs 27.7 mSv, p=0.039). There was excellent agreement of PV anatomy (kappa 0.84, p<0.0001), and a shorter CT scan duration (6 minutes) compared to MRI (41 minutes, p<0.0001). Conclusions Using a high-pitch DSCT protocol, PV imaging can be performed with minimal radiation dose, short scan acquisition, and excellent IQ in patients with SR or AF. This protocol highlights the success of new cardiac CT technology to minimize radiation exposure, giving clinicians a new low-dose imaging alternative to assess PV anatomy. PMID:22586259

Projected cancer risks potentially related to past, current, and future practices in paediatric CT in the United Kingdom, 1990-2020.

PubMed

Journy, Neige M Y; Lee, Choonsik; Harbron, Richard W; McHugh, Kieran; Pearce, Mark S; Berrington de González, Amy

2017-01-03

To project risks of developing cancer and the number of cases potentially induced by past, current, and future computed tomography (CT) scans performed in the United Kingdom in individuals aged <20 years. Organ doses were estimated from surveys of individual scan parameters and CT protocols used in the United Kingdom. Frequencies of scans were estimated from the NHS Diagnostic Imaging Dataset. Excess lifetime risks (ELRs) of radiation-related cancer were calculated as cumulative lifetime risks, accounting for survival probabilities, using the RadRAT risk assessment tool. In 2000-2008, ELRs ranged from 0.3 to 1 per 1000 head scans and 1 to 5 per 1000 non-head scans. ELRs per scan were reduced by 50-70% in 2000-2008 compared with 1990-1995, subsequent to dose reduction over time. The 130 750 scans performed in 2015 in the United Kingdom were projected to induce 64 (90% uncertainty interval (UI): 38-113) future cancers. Current practices would lead to about 300 (90% UI: 230-680) future cancers induced by scans performed in 2016-2020. Absolute excess risks from single exposures would be low compared with background risks, but even small increases in annual CT rates over the next years would substantially increase the number of potential subsequent cancers.

Computed tomography versus water-soluble contrast swallow in the detection of intrathoracic anastomotic leak complicating esophagogastrectomy (Ivor Lewis): a prospective study in 97 patients.

PubMed

Strauss, Christiane; Mal, Frederic; Perniceni, Thierry; Bouzar, Nadia; Lenoir, Stephane; Gayet, Brice; Palau, Robert

2010-04-01

Water-soluble contrast swallow (CS) is usually performed before refeeding for anastomosis assessment after esophagectomy with intrathoracic anastomosis but the sensitivity of CS is low. Another diagnostic approach is based on analysis of computed tomography (CT) scan with oral contrast and of CT mediastinal air images. We undertook to compare them prospectively. Ninety-seven patients with an esophageal carcinoma operated by intrathoracic anastomosis were included prospectively in a study based on a CT scan at postoperative day 3 (without oral and intravenous contrast) and CT scan and CS at day 7. CT scan analysis consisted of assessing contrast and air leakage. In case of doubt, an endoscopy was done. A diagnosis of anastomotic leak was made in 13 patients (13.4%), in 2 cases before day 7 and in 3 beyond day 7. At day 3, 94 CT scans were performed, but the diagnostic value was poor. In 95 patients with both CS and CT scan at day 7, CS disclosed a leak in 5 of 11, and CT scan was abnormal in 8 of 11. Leakage of contrast and/or presence of mediastinal gas had the best negative predictive value (95.8%). Endoscopy was done in 16 patients with only mediastinal gas at day 7 CT scan. It disclosed a normal anastomosis in 11, fibrin deposits in 4, and a leak in 1. In comparison with CS only, CT at day 7 improves the sensitivity and negative predictive value for diagnosing an anastomotic leak. In case of doubt endoscopy is advisable. This approach provides an accurate assessment of the anastomosis before refeeding.

The accuracy of three-dimensional fused deposition modeling (FDM) compared with three-dimensional CT-Scans on the measurement of the mandibular ramus vertical length, gonion-menton length, and gonial angle

NASA Astrophysics Data System (ADS)

Savitri, I. T.; Badri, C.; Sulistyani, L. D.

2017-08-01

Presurgical treatment planning plays an important role in the reconstruction and correction of defects in the craniomaxillofacial region. The advance of solid freeform fabrication techniques has significantly improved the process of preparing a biomodel using computer-aided design and data from medical imaging. Many factors are implicated in the accuracy of the 3D model. To determine the accuracy of three-dimensional fused deposition modeling (FDM) models compared with three-dimensional CT scans in the measurement of the mandibular ramus vertical length, gonion-menton length, and gonial angle. Eight 3D models were produced from the CT scan data (DICOM file) of eight patients at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Indonesia, Cipto Mangunkusumo Hospital. Three measurements were done three times by two examiners. The measurements of the 3D CT scans were made using OsiriX software, while the measurements of the 3D models were made using a digital caliper and goniometry. The measurement results were then compared. There is no significant difference between the measurements of the mandibular ramus vertical length, gonion-menton length, and gonial angle using 3D CT scans and FDM 3D models. FDM 3D models are considered accurate and are acceptable for clinical applications in dental and craniomaxillofacial surgery.

SU-F-I-32: Organ Doses from Pediatric Head CT Scan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, H; Liu, Q; Qiu, J

Purpose: To evaluate the organ doses of pediatric patients who undergoing head CT scan using Monte Carlo (MC) simulation and compare it with measurements in anthropomorphic child phantom.. Methods: A ten years old children voxel phantom was developed from CT images, the voxel size of the phantom was 2mm*2mm*2mm. Organ doses from head CT scan were simulated using MCNPX software, 180 detectors were placed in the voxel phantom to tally the doses of the represented tissues or organs. When performing the simulation, 120 kVp and 88 mA were selected as the scan parameters. The scan range covered from the topmore » of the head to the end of the chain, this protocol was used at CT simulator for radiotherapy. To validate the simulated results, organ doses were measured with radiophotoluminescence (RPL) detectors, placed in the 28 organs of the 10 years old CIRS ATOM phantom. Results: The organ doses results matched well between MC simulation and phantom measurements. The eyes dose was showed to be as expected the highest organ dose: 28.11 mGy by simulation and 27.34 mGy by measurement respectively. Doses for organs not included in the scan volume were much lower than those included in the scan volume, thymus doses were observed more than 10 mGy due the CT protocol for radiotherapy covered more body part than routine head CT scan. Conclusion: As the eyes are superficial organs, they may receive the highest radiation dose during the CT scan. Considering the relatively high radio sensitivity, using shielding material or organ based tube current modulation technique should be encouraged to reduce the eye radiation risks. Scan range was one of the most important factors that affects the organ doses during the CT scan. Use as short as reasonably possible scan range should be helpful to reduce the patient radiation dose. This work was supported by the National Natural Science Foundation of China(11475047)« less

Estimation of the total effective dose from low-dose CT scans and radiopharmaceutical administrations delivered to patients undergoing SPECT/CT explorations.

PubMed

Montes, Carlos; Tamayo, Pilar; Hernandez, Jorge; Gomez-Caminero, Felipe; García, Sofia; Martín, Carlos; Rosero, Angela

2013-08-01

Hybrid imaging, such as SPECT/CT, is used in routine clinical practice, allowing coregistered images of the functional and structural information provided by the two imaging modalities. However, this multimodality imaging may mean that patients are exposed to a higher radiation dose than those receiving SPECT alone. The study aimed to determine the radiation exposure of patients who had undergone SPECT/CT examinations and to relate this to the Background Equivalent Radiation Time (BERT). 145 SPECT/CT studies were used to estimate the total effective dose to patients due to both radiopharmaceutical administrations and low-dose CT scans. The CT contribution was estimated by the Dose-Length Product method. Specific conversion coefficients were calculated for SPECT explorations. The radiation dose from low-dose CTs ranged between 0.6 mSv for head and neck CT and 2.6 mSv for whole body CT scan, representing a maximum of 1 year of background radiation exposure. These values represent a decrease of 80-85% with respect to the radiation dose from diagnostic CT. The radiation exposure from radiopharmaceutical administration varied from 2.1 mSv for stress myocardial perfusion SPECT to 26 mSv for gallium SPECT in patients with lymphoma. The BERT ranged from 1 to 11 years. The contribution of low-dose CT scans to the total radiation dose to patients undergoing SPECT/CT examinations is relatively low compared with the effective dose from radiopharmaceutical administration. When a CT scan is only acquired for anatomical localization and attenuation correction, low-dose CT scan is justified on the basis of its lower dose.

Physical analysis of breast cancer using dual-source computed tomography

NASA Astrophysics Data System (ADS)

Kim, H. J.; Lee, H. K.; Cho, J. H.

2014-12-01

This study was aimed to analyze various physical characteristics of breast cancer using dual-source computed tomography (CT). A phantom study and a clinical trial were performed in order and a 64-multidetector CT device was used for the examinations. In the phantom study, single-source (SS) CT was set up with a conventional scanning condition that is usually applied for breast CT examination and implementation was done at tube voltage of 120 kVp. Dual-source CT acquired images by irradiating X-ray sources with fast switching between two kilovoltage settings (80 and 140 kVp). After scanning, Hounsfield Unit (HU) values and radiation doses in a region of interest were measured and analyzed. In the clinical trial, the HU values were measured and analyzed after single-source computed tomography (SSCT) and dual-source CT in patients diagnosed with breast cancer. Also, the tumor size measured by dual-source CT was compared with the actual tumor size. The phantom study determined that the tumor region was especially measured by dual-source CT, while nylon fiber and specks region were especially measured by SSCT. The radiation dose was high with dual-source CT. The clinical trial showed a higher HU value of cancerous regions when scanned by dual-source CT compared with SSCT.

Head CT scan

MedlinePlus

Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - brain ... conditions: Birth (congenital) defect of the head or brain Brain infection Brain tumor Buildup of fluid inside ...

Pancreatic Cancer Tumor Size on CT Scan Versus Pathologic Specimen: Implications for Radiation Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arvold, Nils D.; Niemierko, Andrzej; Mamon, Harvey J.

2011-08-01

Purpose: Pancreatic cancer primary tumor size measurements are often discordant between computed tomography (CT) and pathologic specimen after resection. Dimensions of the primary tumor are increasingly relevant in an era of highly conformal radiotherapy. Methods and Materials: We retrospectively evaluated 97 consecutive patients with resected pancreatic cancer at two Boston hospitals. All patients had CT scans before surgical resection. Primary endpoints were maximum dimension (in millimeters) of the primary tumor in any direction as reported by the radiologist on CT and by the pathologist for the resected gross fresh specimen. Endoscopic ultrasound (EUS) findings were analyzed if available. Results: Ofmore » the patients, 87 (90%) had preoperative CT scans available for review and 46 (47%) had EUS. Among proximal tumors (n = 69), 40 (58%) had pathologic duodenal invasion, which was seen on CT in only 3 cases. The pathologic tumor size was a median of 7 mm larger compared with CT size for the same patient (range, -15 to 43 mm; p < 0.0001), with 73 patients (84%) having a primary tumor larger on pathology than CT. Endoscopic ultrasound was somewhat more accurate, with pathologic tumor size being a median of only 5 mm larger compared with EUS size (range, -15 to 35 mm; p = 0.0003). Conclusions: Computed tomography scans significantly under-represent pancreatic cancer tumor size compared with pathologic specimens in resectable cases. We propose a clinical target volume expansion formula for the primary tumor based on our data. The high rate of pathologic duodenal invasion suggests a risk of duodenal undercoverage with highly conformal radiotherapy.« less

A comparison of sequential and spiral scanning techniques in brain CT.

PubMed

Pace, Ivana; Zarb, Francis

2015-01-01

To evaluate and compare image quality and radiation dose of sequential computed tomography (CT) examinations of the brain and spiral CT examinations of the brain imaged on a GE HiSpeed NX/I Dual Slice 2CT scanner. A random sample of 40 patients referred for CT examination of the brain was selected and divided into 2 groups. Half of the patients were scanned using the sequential technique; the other half were scanned using the spiral technique. Radiation dose data—both the computed tomography dose index (CTDI) and the dose length product (DLP)—were recorded on a checklist at the end of each examination. Using the European Guidelines on Quality Criteria for Computed Tomography, 4 radiologists conducted a visual grading analysis and rated the level of visibility of 6 anatomical structures considered necessary to produce images of high quality. The mean CTDI(vol) and DLP values were statistically significantly higher (P <.05) with the sequential scans (CTDI(vol): 22.06 mGy; DLP: 304.60 mGy • cm) than with the spiral scans (CTDI(vol): 14.94 mGy; DLP: 229.10 mGy • cm). The mean image quality rating scores for all criteria of the sequential scanning technique were statistically significantly higher (P <.05) in the visual grading analysis than those of the spiral scanning technique. In this local study, the sequential technique was preferred over the spiral technique for both overall image quality and differentiation between gray and white matter in brain CT scans. Other similar studies counter this finding. The radiation dose seen with the sequential CT scanning technique was significantly higher than that seen with the spiral CT scanning technique. However, image quality with the sequential technique was statistically significantly superior (P <.05).

CT scan range estimation using multiple body parts detection: let PACS learn the CT image content.

PubMed

Wang, Chunliang; Lundström, Claes

2016-02-01

The aim of this study was to develop an efficient CT scan range estimation method that is based on the analysis of image data itself instead of metadata analysis. This makes it possible to quantitatively compare the scan range of two studies. In our study, 3D stacks are first projected to 2D coronal images via a ray casting-like process. Trained 2D body part classifiers are then used to recognize different body parts in the projected image. The detected candidate regions go into a structure grouping process to eliminate false-positive detections. Finally, the scale and position of the patient relative to the projected figure are estimated based on the detected body parts via a structural voting. The start and end lines of the CT scan are projected to a standard human figure. The position readout is normalized so that the bottom of the feet represents 0.0, and the top of the head is 1.0. Classifiers for 18 body parts were trained using 184 CT scans. The final application was tested on 136 randomly selected heterogeneous CT scans. Ground truth was generated by asking two human observers to mark the start and end positions of each scan on the standard human figure. When compared with the human observers, the mean absolute error of the proposed method is 1.2% (max: 3.5%) and 1.6% (max: 5.4%) for the start and end positions, respectively. We proposed a scan range estimation method using multiple body parts detection and relative structure position analysis. In our preliminary tests, the proposed method delivered promising results.

TH-C-18A-08: A Management Tool for CT Dose Monitoring, Analysis, and Protocol Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J; Chan, F; Newman, B

2014-06-15

Purpose: To develop a customizable tool for enterprise-wide managing of CT protocols and analyzing radiation dose information of CT exams for a variety of quality control applications Methods: All clinical CT protocols implemented on the 11 CT scanners at our institution were extracted in digital format. The original protocols had been preset by our CT management team. A commercial CT dose tracking software (DoseWatch,GE healthcare,WI) was used to collect exam information (exam date, patient age etc.), scanning parameters, and radiation doses for all CT exams. We developed a Matlab-based program (MathWorks,MA) with graphic user interface which allows to analyze themore » scanning protocols with the actual dose estimates, and compare the data to national (ACR,AAPM) and internal reference values for CT quality control. Results: The CT protocol review portion of our tool allows the user to look up the scanning and image reconstruction parameters of any protocol on any of the installed CT systems among about 120 protocols per scanner. In the dose analysis tool, dose information of all CT exams (from 05/2013 to 02/2014) was stratified on a protocol level, and within a protocol down to series level, i.e. each individual exposure event. This allows numerical and graphical review of dose information of any combination of scanner models, protocols and series. The key functions of the tool include: statistics of CTDI, DLP and SSDE, dose monitoring using user-set CTDI/DLP/SSDE thresholds, look-up of any CT exam dose data, and CT protocol review. Conclusion: our inhouse CT management tool provides radiologists, technologists and administration a first-hand near real-time enterprise-wide knowledge on CT dose levels of different exam types. Medical physicists use this tool to manage CT protocols, compare and optimize dose levels across different scanner models. It provides technologists feedback on CT scanning operation, and knowledge on important dose baselines and thresholds.« less

Hard x-ray micro-tomography of a human head post-mortem as a gold standard to compare x-ray modalities

NASA Astrophysics Data System (ADS)

Dalstra, M.; Schulz, G.; Dagassan-Berndt, D.; Verna, C.; Müller-Gerbl, M.; Müller, B.

2016-10-01

An entire human head obtained at autopsy was micro-CT scanned in a nano/micro-CT scanner in a 6-hour long session. Despite the size of the head, it could still be scanned with a pixel size of 70 μm. The aim of this study was to obtain an optimal quality 3D data-set to be used as baseline control in a larger study comparing the image quality of various cone beam CT systems currently used in dentistry. The image quality of the micro-CT scans was indeed better than the ones of the clinical imaging modalities, both with regard to noise and streak artifacts due to metal dental implants. Bony features in the jaws, like the trabecular architecture and the thin wall of the alveolar bone were clearly visible. Therefore, the 3D micro-CT data-set can be used as the gold standard for linear, angular, and volumetric measurements of anatomical features in and around the oral cavity when comparing clinical imaging modalities.

Impact of adaptive statistical iterative reconstruction on radiation dose in evaluation of trauma patients.

PubMed

Maxfield, Mark W; Schuster, Kevin M; McGillicuddy, Edward A; Young, Calvin J; Ghita, Monica; Bokhari, S A Jamal; Oliva, Isabel B; Brink, James A; Davis, Kimberly A

2012-12-01

A recent study showed that computed tomographic (CT) scans contributed 93% of radiation exposure of 177 patients admitted to our Level I trauma center. Adaptive statistical iterative reconstruction (ASIR) is an algorithm that reduces the noise level in reconstructed images and therefore allows the use of less ionizing radiation during CT scans without significantly affecting image quality. ASIR was instituted on all CT scans performed on trauma patients in June 2009. Our objective was to determine if implementation of ASIR reduced radiation dose without compromising patient outcomes. We identified 300 patients activating the trauma system before and after the implementation of ASIR imaging. After applying inclusion criteria, 245 charts were reviewed. Baseline demographics, presenting characteristics, number of delayed diagnoses, and missed injuries were recorded. The postexamination volume CT dose index (CTDIvol) and dose-length product (DLP) reported by the scanner for CT scans of the chest, abdomen, and pelvis and CT scans of the brain and cervical spine were recorded. Subjective image quality was compared between the two groups. For CT scans of the chest, abdomen, and pelvis, the mean CTDIvol (17.1 mGy vs. 14.2 mGy; p < 0.001) and DLP (1,165 mGy·cm vs. 1,004 mGy·cm; p < 0.001) was lower for studies performed with ASIR. For CT scans of the brain and cervical spine, the mean CTDIvol (61.7 mGy vs. 49.6 mGy; p < 0.001) and DLP (1,327 mGy·cm vs. 1,067 mGy·cm; p < 0.001) was lower for studies performed with ASIR. There was no subjective difference in image quality between ASIR and non-ASIR scans. All CT scans were deemed of good or excellent image quality. There were no delayed diagnoses or missed injuries related to CT scanning identified in either group. Implementation of ASIR imaging for CT scans performed on trauma patients led to a nearly 20% reduction in ionizing radiation without compromising outcomes or image quality. Therapeutic study, level IV.

Impact of adaptive statistical iterative reconstruction on radiation dose in evaluation of trauma patients

PubMed Central

Maxfield, Mark W.; Schuster, Kevin M.; McGillicuddy, Edward A.; Young, Calvin J.; Ghita, Monica; Bokhari, S.A. Jamal; Oliva, Isabel B.; Brink, James A.; Davis, Kimberly A.

2013-01-01

BACKGROUND A recent study showed that computed tomographic (CT) scans contributed 93% of radiation exposure of 177 patients admitted to our Level I trauma center. Adaptive statistical iterative reconstruction (ASIR) is an algorithm that reduces the noise level in reconstructed images and therefore allows the use of less ionizing radiation during CT scans without significantly affecting image quality. ASIR was instituted on all CT scans performed on trauma patients in June 2009. Our objective was to determine if implementation of ASIR reduced radiation dose without compromising patient outcomes. METHODS We identified 300 patients activating the trauma system before and after the implementation of ASIR imaging. After applying inclusion criteria, 245 charts were reviewed. Baseline demographics, presenting characteristics, number of delayed diagnoses, and missed injuries were recorded. The postexamination volume CT dose index (CTDIvol) and dose-length product (DLP)reported by the scanner for CT scans of the chest, abdomen, and pelvis and CT scans of the brain and cervical spine were recorded. Subjective image quality was compared between the two groups. RESULTS For CT scans of the chest, abdomen, and pelvis, the mean CTDIvol(17.1 mGy vs. 14.2 mGy; p < 0.001) and DLP (1,165 mGy·cm vs. 1,004 mGy·cm; p < 0.001) was lower for studies performed with ASIR. For CT scans of the brain and cervical spine, the mean CTDIvol(61.7 mGy vs. 49.6 mGy; p < 0.001) and DLP (1,327 mGy·cm vs. 1,067 mGy·cm; p < 0.001) was lower for studies performed with ASIR. There was no subjective difference in image quality between ASIR and non-ASIR scans. All CT scans were deemed of good or excellent image quality. There were no delayed diagnoses or missed injuries related to CT scanning identified in either group. CONCLUSION Implementation of ASIR imaging for CT scans performed on trauma patients led to a nearly 20% reduction in ionizing radiation without compromising outcomes or image quality. PMID:23147183

Dual energy CT with one full scan and a second sparse-view scan using structure preserving iterative reconstruction (SPIR)

NASA Astrophysics Data System (ADS)

Wang, Tonghe; Zhu, Lei

2016-09-01

Conventional dual-energy CT (DECT) reconstruction requires two full-size projection datasets with two different energy spectra. In this study, we propose an iterative algorithm to enable a new data acquisition scheme which requires one full scan and a second sparse-view scan for potential reduction in imaging dose and engineering cost of DECT. A bilateral filter is calculated as a similarity matrix from the first full-scan CT image to quantify the similarity between any two pixels, which is assumed unchanged on a second CT image since DECT scans are performed on the same object. The second CT image from reduced projections is reconstructed by an iterative algorithm which updates the image by minimizing the total variation of the difference between the image and its filtered image by the similarity matrix under data fidelity constraint. As the redundant structural information of the two CT images is contained in the similarity matrix for CT reconstruction, we refer to the algorithm as structure preserving iterative reconstruction (SPIR). The proposed method is evaluated on both digital and physical phantoms, and is compared with the filtered-backprojection (FBP) method, the conventional total-variation-regularization-based algorithm (TVR) and prior-image-constrained-compressed-sensing (PICCS). SPIR with a second 10-view scan reduces the image noise STD by a factor of one order of magnitude with same spatial resolution as full-view FBP image. SPIR substantially improves over TVR on the reconstruction accuracy of a 10-view scan by decreasing the reconstruction error from 6.18% to 1.33%, and outperforms TVR at 50 and 20-view scans on spatial resolution with a higher frequency at the modulation transfer function value of 10% by an average factor of 4. Compared with the 20-view scan PICCS result, the SPIR image has 7 times lower noise STD with similar spatial resolution. The electron density map obtained from the SPIR-based DECT images with a second 10-view scan has an average error of less than 1%.

Single energy micro CT SkyScan 1173 for the characterization of urinary stone

NASA Astrophysics Data System (ADS)

Fitri, L. A.; Asyana, V.; Ridwan, T.; Anwary, F.; Soekersi, H.; Latief, F. D. E.; Haryanto, F.

2016-08-01

A urinary stone is a solid piece of material produced from crystallization of excreted substances in the urine. Knowledge of the composition of urinary stones is essential to determine the suitable treatment for the patient. The aim of this research was to characterize urinary stones using single energy micro CT SkyScan 1173. Six human urinary stones were scanned in vitro using 80 kV in micro CT SkyScan 1173. The produced projection, images, were reconstructed using NRecon (in-house software from SkyScan). The images of urinary stones were analyzed using CT Analyser (CT An) to obtain information of the internal structure and the Hounsfield Unit (HU) value to determine the information regarding the composition of the urinary stones, respectively. The average HU values from certain region of interests in the same slice were compared with spectral curves of known materials from National Institute of Standards and Technology (NIST). From the analysis, the composition of the six scanned stones were obtained. Two stones are composed of cystine, two are composed of struvite, two other stones are composed of struvite+cystine. In conclusion, the single energy micro CT with 80 kV can be used identifying cystine and struvite urinary stone.

Effect of emergency department CT on neuroimaging case volume and positive scan rates.

PubMed

Oguz, Kader Karli; Yousem, David M; Deluca, Tom; Herskovits, Edward H; Beauchamp, Norman J

2002-09-01

The authors performed this study to determine the effect a computed tomographic (CT) scanner in the emergency department (ED) has on neuroimaging case volume and positive scan rates. The total numbers of ED visits and neuroradiology CT scans requested from the ED were recorded for 1998 and 2000, the years before and after the installation of a CT unit in the ED. For each examination type (brain, face, cervical spine), studies were graded for major findings (those that affected patient care), minor findings, and normal findings. The CT utilization rates and positive study rates were compared for each type of study performed for both years. There was a statistically significant increase in the utilization rate after installation of the CT unit (P < .001). The fractions of studies with major findings, minor findings, and normal findings changed significantly after installation of the CT unit for facial examinations (P = .002) but not for brain (P = .12) or cervical spine (P = .24) examinations. In all types of studies, the percentage of normal examinations increased. In toto, there was a significant decrease in the positive scan rate after installation of the CT scanner (P = .004). After installation of a CT scanner in the ED, there was increased utilization and a decreased rate of positive neuroradiologic examinations, the latter primarily due to lower positive rates for facial CT scans.

Deep Learning MR Imaging-based Attenuation Correction for PET/MR Imaging.

PubMed

Liu, Fang; Jang, Hyungseok; Kijowski, Richard; Bradshaw, Tyler; McMillan, Alan B

2018-02-01

Purpose To develop and evaluate the feasibility of deep learning approaches for magnetic resonance (MR) imaging-based attenuation correction (AC) (termed deep MRAC) in brain positron emission tomography (PET)/MR imaging. Materials and Methods A PET/MR imaging AC pipeline was built by using a deep learning approach to generate pseudo computed tomographic (CT) scans from MR images. A deep convolutional auto-encoder network was trained to identify air, bone, and soft tissue in volumetric head MR images coregistered to CT data for training. A set of 30 retrospective three-dimensional T1-weighted head images was used to train the model, which was then evaluated in 10 patients by comparing the generated pseudo CT scan to an acquired CT scan. A prospective study was carried out for utilizing simultaneous PET/MR imaging for five subjects by using the proposed approach. Analysis of covariance and paired-sample t tests were used for statistical analysis to compare PET reconstruction error with deep MRAC and two existing MR imaging-based AC approaches with CT-based AC. Results Deep MRAC provides an accurate pseudo CT scan with a mean Dice coefficient of 0.971 ± 0.005 for air, 0.936 ± 0.011 for soft tissue, and 0.803 ± 0.021 for bone. Furthermore, deep MRAC provides good PET results, with average errors of less than 1% in most brain regions. Significantly lower PET reconstruction errors were realized with deep MRAC (-0.7% ± 1.1) compared with Dixon-based soft-tissue and air segmentation (-5.8% ± 3.1) and anatomic CT-based template registration (-4.8% ± 2.2). Conclusion The authors developed an automated approach that allows generation of discrete-valued pseudo CT scans (soft tissue, bone, and air) from a single high-spatial-resolution diagnostic-quality three-dimensional MR image and evaluated it in brain PET/MR imaging. This deep learning approach for MR imaging-based AC provided reduced PET reconstruction error relative to a CT-based standard within the brain compared with current MR imaging-based AC approaches. © RSNA, 2017 Online supplemental material is available for this article.

Computer tomographic imaging and anatomic correlation of the human brain: A comparative atlas of thin CT-scan sections and correlated neuro-anatomic preparations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plets, C.; Baert, A.L.; Nijs, G.L.

1986-01-01

It is of the greatest importance to the radiologist, the neurologist and the neurosurgeon to be able to localize topographically a pathological brain process on the CT scan as precisely as possible. For that purpose, the identification of as many anatomical structures as possible on the CT scan image are necessary and indispensable. In this atlas a great number of detailed anatomical data on frontal horizontal CT scan sections, each being only 2 mm thick, are indicated, e.g. the cortical gyri, the basal ganglia, details of the white matter, extracranial muscles and blood vessels, parts of the base and themore » vault of the skull, etc. The very precise topographical description of the numerous CT scan images was realized by the author by confrontation of these images with the corresponding anatomical sections of the same brain specimen, performed by an original technique.« less

Weight-Bearing Cone-Beam CT Scan Assessment of Stability of Supination External Rotation Ankle Fractures in a Cadaver Model.

PubMed

Lawlor, Mark C; Kluczynski, Melissa A; Marzo, John M

2018-03-01

The utility of computed tomography (CT) for measuring medial clear space (MCS) for determination of the stability of supination external rotation (SER) ankle fractures and in comparison to standard radiographs is unknown. We compared MCS on gravity stress (GS) radiographs to GS and weight bearing (WB) cone-beam CT (CBCT). An AO SER 44B3.1 ankle fracture was simulated in 10 human cadavers, also serving as controls. MCS was measured on GS radiographs, GS CBCT, and a simulated WB CBCT scan. Specimens were stable if MCS was <5 mm and unstable if MCS was ≥5 mm. Paired t tests were used to compare MCS from each imaging modality for controls versus SER injuries and stable versus unstable specimens. Compared with controls assessed by GS radiographs, MCS was greater for an SER injury when assessed by GS radiograph and GS CBCT scan within the stable group. Compared with controls assessed by GS radiographs, MCS was greater for SER injuries when assessed by GS radiograph, GS CBCT scan, and WB CBCT within the unstable group. MCS was reduced for stable versus unstable SER injuries assessed by WB CBCT. In a cadaveric model of SER ankle fracture, the medial clear space was statistically significantly greater for the experimental condition when assessed by gravity stress radiograph and gravity stress CBCT scan. Under weight-bearing conditions, the cone-beam CT scanner distinguished between stable and unstable ankles in the experimental condition. This study suggests that a WB cone-beam CT scan may be able to distinguish between stable and unstable SER ankle fractures and influence operative decision making.

Lung texture in serial thoracic CT scans: correlation with radiologist-defined severity of acute changes following radiation therapy

NASA Astrophysics Data System (ADS)

Cunliffe, Alexandra R.; Armato, Samuel G., III; Straus, Christopher; Malik, Renuka; Al-Hallaq, Hania A.

2014-09-01

This study examines the correlation between the radiologist-defined severity of normal tissue damage following radiation therapy (RT) for lung cancer treatment and a set of mathematical descriptors of computed tomography (CT) scan texture (‘texture features’). A pre-therapy CT scan and a post-therapy CT scan were retrospectively collected under IRB approval for each of the 25 patients who underwent definitive RT (median dose: 66 Gy). Sixty regions of interest (ROIs) were automatically identified in the non-cancerous lung tissue of each post-therapy scan. A radiologist compared post-therapy scan ROIs with pre-therapy scans and categorized each as containing no abnormality, mild abnormality, moderate abnormality, or severe abnormality. Twenty texture features that characterize gray-level intensity, region morphology, and gray-level distribution were calculated in post-therapy scan ROIs and compared with anatomically matched ROIs in the pre-therapy scan. Linear regression and receiver operating characteristic (ROC) analysis were used to compare the percent feature value change (ΔFV) between ROIs at each category of visible radiation damage. Most ROIs contained no (65%) or mild abnormality (30%). ROIs with moderate (3%) or severe (2%) abnormalities were observed in 9 patients. For 19 of 20 features, ΔFV was significantly different among severity levels. For 12 features, significant differences were observed at every level. Compared with regions with no abnormalities, ΔFV for these 12 features increased, on average, by 1.5%, 12%, and 30%, respectively, for mild, moderate, and severe abnormalitites. Area under the ROC curve was largest when comparing ΔFV in the highest severity level with the remaining three categories (mean AUC across features: 0.84). In conclusion, 19 features that characterized the severity of radiologic changes from pre-therapy scans were identified. These features may be used in future studies to quantify acute normal lung tissue damage following RT. Presented, in part at the IASLC 15th World Conference on Lung Conference, Sydney, AUS (2013).

Spiral computed tomography phase-space source model in the BEAMnrc/EGSnrc Monte Carlo system: implementation and validation.

PubMed

Kim, Sangroh; Yoshizumi, Terry T; Yin, Fang-Fang; Chetty, Indrin J

2013-04-21

Currently, the BEAMnrc/EGSnrc Monte Carlo (MC) system does not provide a spiral CT source model for the simulation of spiral CT scanning. We developed and validated a spiral CT phase-space source model in the BEAMnrc/EGSnrc system. The spiral phase-space source model was implemented in the DOSXYZnrc user code of the BEAMnrc/EGSnrc system by analyzing the geometry of spiral CT scan-scan range, initial angle, rotational direction, pitch, slice thickness, etc. Table movement was simulated by changing the coordinates of the isocenter as a function of beam angles. Some parameters such as pitch, slice thickness and translation per rotation were also incorporated into the model to make the new phase-space source model, designed specifically for spiral CT scan simulations. The source model was hard-coded by modifying the 'ISource = 8: Phase-Space Source Incident from Multiple Directions' in the srcxyznrc.mortran and dosxyznrc.mortran files in the DOSXYZnrc user code. In order to verify the implementation, spiral CT scans were simulated in a CT dose index phantom using the validated x-ray tube model of a commercial CT simulator for both the original multi-direction source (ISOURCE = 8) and the new phase-space source model in the DOSXYZnrc system. Then the acquired 2D and 3D dose distributions were analyzed with respect to the input parameters for various pitch values. In addition, surface-dose profiles were also measured for a patient CT scan protocol using radiochromic film and were compared with the MC simulations. The new phase-space source model was found to simulate the spiral CT scanning in a single simulation run accurately. It also produced the equivalent dose distribution of the ISOURCE = 8 model for the same CT scan parameters. The MC-simulated surface profiles were well matched to the film measurement overall within 10%. The new spiral CT phase-space source model was implemented in the BEAMnrc/EGSnrc system. This work will be beneficial in estimating the spiral CT scan dose in the BEAMnrc/EGSnrc system.

Advantages and limitations of computed tomography scans for treatment planning of lung cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mira, J.G.; Potter, J.L.; Fullerton, G.D.

1982-09-01

Forty-five Chest computed tomography (CT) scans performed on patients with lung carcinoma (LC) were evaluated in an attempt to understand the pattern of intrathoracic tumor spread and the advantages and limitations this technique offers for treatment planning when compared to planning done by conventional X rays. The following findings can help treatment planning. (1) When regular X rays do not show location (i.e., hemithorax opacification), CT scan will show it in 68% of patients. If regular X rays show a well localized mass, unsuspected tumor extensions were disclosed in 78% of these patients. Hence, CT scans should be done inmore » all LC patients prior to treatment planning; (2) Mediastinal masses frequently spread anteriorly toward the sternum and posteriorly around the vertebral bodies toward the cord and costal pleura. This should be considered for radiotherapy boost techniques; (3) Lung masses spread in one third of cases toward the lateral costal pleura. Thus, the usual 1-2cm of safety margin around the LC are not sufficient in some cases; (4) Tumor size can appear much smaller in regular X rays than in CT scans. Hence, CT scans are necessary for accurate staging and evaluation of tumor response. Some CT scan limitations are: (1) Atelectasis blends with tumor in approximately half of the patients, thus obscuring tumor boundaries; (2) CT numbers and contrast enhancement did not help to differentiate between these two structures; and (3) Limited definition of CT scan prevents investigation of suspected microscopic spread around tumor masses.« less

Dosimetry in MARS spectral CT: TOPAS Monte Carlo simulations and ion chamber measurements.

PubMed

Lu, Gray; Marsh, Steven; Damet, Jerome; Carbonez, Pierre; Laban, John; Bateman, Christopher; Butler, Anthony; Butler, Phil

2017-06-01

Spectral computed tomography (CT) is an up and coming imaging modality which shows great promise in revealing unique diagnostic information. Because this imaging modality is based on X-ray CT, it is of utmost importance to study the radiation dose aspects of its use. This study reports on the implementation and evaluation of a Monte Carlo simulation tool using TOPAS for estimating dose in a pre-clinical spectral CT scanner known as the MARS scanner. Simulated estimates were compared with measurements from an ionization chamber. For a typical MARS scan, TOPAS estimated for a 30 mm diameter cylindrical phantom a CT dose index (CTDI) of 29.7 mGy; CTDI was measured by ion chamber to within 3% of TOPAS estimates. Although further development is required, our investigation of TOPAS for estimating MARS scan dosimetry has shown its potential for further study of spectral scanning protocols and dose to scanned objects.

CT scans in young people in Northern England: trends and patterns 1993–2002

PubMed Central

Pearce, Mark S.; Salotti, Jane A.; McHugh, Kieran; Metcalf, Wenhua; Kim, Kwang P.; Craft, Alan W.; Parker, Louise; Ron, Elaine

2014-01-01

Background Although CT can be greatly beneficial, its relatively high radiation doses have caused public health concerns. Objective To assess patterns in CT usage among patients aged less than 22 years in Northern England during the period 1993–2002. Materials and methods Electronic data were obtained from radiology information systems of all nine National Health Service trusts in the region. Results A total of 38,681 scans had been performed in 20,483 patients aged less than 22 years. The number of CT examinations rose, with the steepest increase between 1997 and 2000. The number of patients scanned per year increased less dramatically, with 2.24/1,000 population aged less than 22 years having one scan or more in 1993 compared to 3.54/1,000 in 2002. This reflects an increase in the median number of scans per patient, which rose from 1 in 1993 to 2 by 1999. More than 70% of CT examinations were of the head, with the number of head examinations varying with time and patient age. Conclusion The frequency of CT scans in this population more than doubled during the study period. This is partly, but not wholly, explained by an increase in the number of scans per patient. PMID:21594548

Assessing stapes piston position using computed tomography: a cadaveric study.

PubMed

Hahn, Yoav; Diaz, Rodney; Hartman, Jonathan; Bobinski, Matthew; Brodie, Hilary

2009-02-01

Temporal bone computed tomographic (CT) scanning in the postoperative stapedotomy patient is inaccurate in assessing stapes piston position within the vestibule. Poststapedotomy patients that have persistent vertigo may undergo CT scanning to assess the position of the stapes piston within the vestibule to rule out overly deep insertion. Vertigo is a recognized complication of the deep piston, and CT evaluation is often recommended. The accuracy of CT scan in this setting is unestablished. Stapedotomy was performed on 12 cadaver ears, and stainless steel McGee pistons were placed. The cadaver heads were then scanned using a fine-cut temporal bone protocol. Temporal bone dissection was performed with microscopic measurement of the piston depth in the vestibule. These values were compared with depth of intravestibular penetration measured on CT scan by 4 independent measurements. The intravestibular penetration as assessed by computed tomography was consistently greater than the value found on cadaveric anatomic dissection. The radiographic bias was greater when piston location within the vestibule was shallower. The axial CT scan measurement was 0.53 mm greater, on average, than the anatomic measurement. On average, the coronal CT measurement was 0.68 mm greater than the anatomic measurement. The degree of overestimation of penetration, however, was highly inconsistent. Standard temporal bone CT scan is neither an accurate nor precise examination of stapes piston depth within the vestibule. We found that CT measurement consistently overstated intravestibular piston depth. Computed tomography is not a useful study in the evaluation of piston depth for poststapedectomy vertigo and is of limited value in this setting.

Reduction in radiation doses from paediatric CT scans in Great Britain.

PubMed

Lee, Choonsik; Pearce, Mark S; Salotti, Jane A; Harbron, Richard W; Little, Mark P; McHugh, Kieran; Chapple, Claire-Louise; Berrington de Gonzalez, Amy

2016-01-01

Although CT scans provide great medical benefits, concerns have been raised about the magnitude of possible associated cancer risk, particularly in children who are more sensitive to radiation than adults. Unnecessary high doses during CT examinations can also be delivered to children, if the scan parameters are not adjusted for patient age and size. We conducted the first survey to directly assess the trends in CT scan parameters and doses for paediatric CT scans performed in Great Britain between 1978 and 2008. We retrieved 1073 CT film sets from 36 hospitals. The patients were 0-19 years old, and CT scans were conducted between 1978 and 2008. We extracted scan parameters from each film including tube current-time product [milliampere seconds (mAs)], tube potential [peak kilovoltage (kVp)] and manufacturer and model of the CT scanner. We estimated the mean mAs for head and trunk (chest and abdomen/pelvis) scans, according to patient age (0-4, 5-9, 10-14 and 15-19 years) and scan year (<1990, 1990-1994, 1995-1999 and ≥2000), and then derived the volumetric CT dose index and estimated organ doses. For head CT scans, mean mAs decreased by about 47% on average from before 1990 to after 2000, with the decrease starting around 1990. The mean mAs for head CTs did not vary with age before 1990, whereas slightly lower mAs values were used for younger patients after 1990. Similar declines in mAs were observed for trunk CTs: a 46% decline on an average from before 1990 to after 2000. Although mean mAs for trunk CTs did not vary with age before 1990, the value varied markedly by age, from 63 mAs for age 0-4 years compared with 315 mAs for those aged >15 years after 2000. No material changes in kVp were found. Estimated brain-absorbed dose from head CT scans decreased from 62 mGy before 1990 to approximately 30 mGy after 2000. For chest CT scans, the lung dose to children aged 0-4 years decreased from 28 mGy before 1990 to 4 mGy after 2000. We found that mAs for head and trunk CTs was approximately halved starting around 1990, and age-specific mAs was generally used for paediatric scans after this date. These changes will have substantially reduced the radiation exposure to children from CT scans in Great Britain. The study shows that mAs and major organ doses for paediatric CT scans in Great Britain began to decrease around 1990.

Reduction in radiation doses from paediatric CT scans in Great Britain

PubMed Central

Pearce, Mark S; Salotti, Jane A; Harbron, Richard W; Little, Mark P; McHugh, Kieran; Chapple, Claire-Louise; Berrington de Gonzalez, Amy

2016-01-01

Objective: Although CT scans provide great medical benefits, concerns have been raised about the magnitude of possible associated cancer risk, particularly in children who are more sensitive to radiation than adults. Unnecessary high doses during CT examinations can also be delivered to children, if the scan parameters are not adjusted for patient age and size. We conducted the first survey to directly assess the trends in CT scan parameters and doses for paediatric CT scans performed in Great Britain between 1978 and 2008. Methods: We retrieved 1073 CT film sets from 36 hospitals. The patients were 0–19 years old, and CT scans were conducted between 1978 and 2008. We extracted scan parameters from each film including tube current–time product [milliampere seconds (mAs)], tube potential [peak kilovoltage (kVp)] and manufacturer and model of the CT scanner. We estimated the mean mAs for head and trunk (chest and abdomen/pelvis) scans, according to patient age (0–4, 5–9, 10–14 and 15–19 years) and scan year (<1990, 1990–1994, 1995–1999 and ≥2000), and then derived the volumetric CT dose index and estimated organ doses. Results: For head CT scans, mean mAs decreased by about 47% on average from before 1990 to after 2000, with the decrease starting around 1990. The mean mAs for head CTs did not vary with age before 1990, whereas slightly lower mAs values were used for younger patients after 1990. Similar declines in mAs were observed for trunk CTs: a 46% decline on an average from before 1990 to after 2000. Although mean mAs for trunk CTs did not vary with age before 1990, the value varied markedly by age, from 63 mAs for age 0–4 years compared with 315 mAs for those aged >15 years after 2000. No material changes in kVp were found. Estimated brain-absorbed dose from head CT scans decreased from 62 mGy before 1990 to approximately 30 mGy after 2000. For chest CT scans, the lung dose to children aged 0–4 years decreased from 28 mGy before 1990 to 4 mGy after 2000. Conclusion: We found that mAs for head and trunk CTs was approximately halved starting around 1990, and age-specific mAs was generally used for paediatric scans after this date. These changes will have substantially reduced the radiation exposure to children from CT scans in Great Britain. Advances in knowledge: The study shows that mAs and major organ doses for paediatric CT scans in Great Britain began to decrease around 1990. PMID:26864156

SU-F-R-40: Robustness Test of Computed Tomography Textures of Lung Tissues to Varying Scanning Protocols Using a Realistic Phantom Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S; Markel, D; Hegyi, G

2016-06-15

Purpose: The reliability of computed tomography (CT) textures is an important element of radiomics analysis. This study investigates the dependency of lung CT textures on different breathing phases and changes in CT image acquisition protocols in a realistic phantom setting. Methods: We investigated 11 CT texture features for radiation-induced lung disease from 3 categories (first-order, grey level co-ocurrence matrix (GLCM), and Law’s filter). A biomechanical swine lung phantom was scanned at two breathing phases (inhale/exhale) and two scanning protocols set for PET/CT and diagnostic CT scanning. Lung volumes acquired from the CT images were divided into 2-dimensional sub-regions with amore » grid spacing of 31 mm. The distribution of the evaluated texture features from these sub-regions were compared between the two scanning protocols and two breathing phases. The significance of each factor on feature values were tested at 95% significance level using analysis of covariance (ANCOVA) model with interaction terms included. Robustness of a feature to a scanning factor was defined as non-significant dependence on the factor. Results: Three GLCM textures (variance, sum entropy, difference entropy) were robust to breathing changes. Two GLCM (variance, sum entropy) and 3 Law’s filter textures (S5L5, E5L5, W5L5) were robust to scanner changes. Moreover, the two GLCM textures (variance, sum entropy) were consistent across all 4 scanning conditions. First-order features, especially Hounsfield unit intensity features, presented the most drastic variation up to 39%. Conclusion: Amongst the studied features, GLCM and Law’s filter texture features were more robust than first-order features. However, the majority of the features were modified by either breathing phase or scanner changes, suggesting a need for calibration when retrospectively comparing scans obtained at different conditions. Further investigation is necessary to identify the sensitivity of individual image acquisition parameters.« less

Paediatric blunt abdominal trauma - are we doing too many computed tomography scans?

PubMed

Arnold, M; Moore, S W

2013-02-14

Blunt abdominal trauma in childhood contributes significantly to both morbidity and mortality. Selective non-operative management of blunt abdominal trauma in children depends on both diagnostic and clinical factors. Computed tomography (CT) scanning is widely used to facilitate better management. Increased availability of CT may, however, result in its overuse in the management of blunt abdominal trauma in children, which carries significant radiation exposure risks. To evaluate the use and value of CT scanning in the overall management and outcome of blunt abdominal trauma in children in the Tygerberg Academic Hospital trauma unit, Parow, Cape Town, South Africa, before and after improved access to CT as a result of installation of a new rapid CT scanner in the trauma management area (previously the scanner had been 4 floors away). Patients aged 0 - 13 years who were referred with blunt abdominal trauma due to vehicle-related accidents before the introduction of the new CT scanner (group 1, n=66, November 2003 - March 2009) were compared with those seen in the 1-year period after the scanner was installed (group 2, n=37, April 2009 - April 2010). Details of clinical presentation, imaging results and their influence on management were retrospectively reviewed. A follow-up group was evaluated after stricter criteria for abdominal CT scanning (viz. prior evaluation by paediatric surgical personnel) were introduced (group 3, n=14, November 2011 - May 2012) to evaluate the impact of this clinical screening on the rate of negative scans. There were 66 patients in group 1 and 37 in group 2. An apparent increase in CT use with increased availability was accompanied by a marked increase in negative CT scans (38.9% compared with 6.2%; p<0.006). Despite a slightly higher prevalence of associated injuries in group 2, as well as a slightly longer length of hospital stay, there was a similar prevalence of intra-abdominal injuries detected in positive scans in the two groups. In addition, rates of small-bowel perforation in the two groups were similar. The rate of negative scans in group 3 was 46.2% (6/13), but all except one of these patients had a severe brain injury preventing adequate clinical evaluation of intra-abdominal injury. CT scanning for blunt abdominal trauma in children is essential in the presence of appropriate clinical indications. Ease of access probably increases availability, but the rate of negative scans may increase. Management guidelines should be in place to direct CT scanning to cases in which clinical examination and/or other modalities indicate a likelihood of intra-abdominal injury. The principle of 'as low (radiation) dose as reasonably achievable' (ALARA) should be adhered to because of the increased radiation exposure risks in children.

Estimating local noise power spectrum from a few FBP-reconstructed CT scans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, Rongping, E-mail: rongping.zeng@fda.hhs.gov; Gavrielides, Marios A.; Petrick, Nicholas

Purpose: Traditional ways to estimate 2D CT noise power spectrum (NPS) involve an ensemble average of the power spectrums of many noisy scans. When only a few scans are available, regions of interest are often extracted from different locations to obtain sufficient samples to estimate the NPS. Using image samples from different locations ignores the nonstationarity of CT noise and thus cannot accurately characterize its local properties. The purpose of this work is to develop a method to estimate local NPS using only a few fan-beam CT scans. Methods: As a result of FBP reconstruction, the CT NPS has themore » same radial profile shape for all projection angles, with the magnitude varying with the noise level in the raw data measurement. This allows a 2D CT NPS to be factored into products of a 1D angular and a 1D radial function in polar coordinates. The polar separability of CT NPS greatly reduces the data requirement for estimating the NPS. The authors use this property and derive a radial NPS estimation method: in brief, the radial profile shape is estimated from a traditional NPS based on image samples extracted at multiple locations. The amplitudes are estimated by fitting the traditional local NPS to the estimated radial profile shape. The estimated radial profile shape and amplitudes are then combined to form a final estimate of the local NPS. We evaluate the accuracy of the radial NPS method and compared it to traditional NPS methods in terms of normalized mean squared error (NMSE) and signal detectability index. Results: For both simulated and real CT data sets, the local NPS estimated with no more than six scans using the radial NPS method was very close to the reference NPS, according to the metrics of NMSE and detectability index. Even with only two scans, the radial NPS method was able to achieve a fairly good accuracy. Compared to those estimated using traditional NPS methods, the accuracy improvement was substantial when a few scans were available. Conclusions: The radial NPS method was shown to be accurate and efficient in estimating the local NPS of FBP-reconstructed 2D CT images. It presents strong advantages over traditional NPS methods when the number of scans is limited and can be extended to estimate the in-plane NPS of cone-beam CT and multislice helical CT scans.« less

First Clinical Investigation of Cone Beam Computed Tomography and Deformable Registration for Adaptive Proton Therapy for Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veiga, Catarina; Janssens, Guillaume; Teng, Ching-Ling

2016-05-01

Purpose: An adaptive proton therapy workflow using cone beam computed tomography (CBCT) is proposed. It consists of an online evaluation of a fast range-corrected dose distribution based on a virtual CT (vCT) scan. This can be followed by more accurate offline dose recalculation on the vCT scan, which can trigger a rescan CT (rCT) for replanning. Methods and Materials: The workflow was tested retrospectively for 20 consecutive lung cancer patients. A diffeomorphic Morphon algorithm was used to generate the lung vCT by deforming the average planning CT onto the CBCT scan. An additional correction step was applied to account formore » anatomic modifications that cannot be modeled by deformation alone. A set of clinical indicators for replanning were generated according to the water equivalent thickness (WET) and dose statistics and compared with those obtained on the rCT scan. The fast dose approximation consisted of warping the initial planned dose onto the vCT scan according to the changes in WET. The potential under- and over-ranges were assessed as a variation in WET at the target's distal surface. Results: The range-corrected dose from the vCT scan reproduced clinical indicators similar to those of the rCT scan. The workflow performed well under different clinical scenarios, including atelectasis, lung reinflation, and different types of tumor response. Between the vCT and rCT scans, we found a difference in the measured 95% percentile of the over-range distribution of 3.4 ± 2.7 mm. The limitations of the technique consisted of inherent uncertainties in deformable registration and the drawbacks of CBCT imaging. The correction step was adequate when gross errors occurred but could not recover subtle anatomic or density changes in tumors with complex topology. Conclusions: A proton therapy workflow based on CBCT provided clinical indicators similar to those using rCT for patients with lung cancer with considerable anatomic changes.« less

SU-F-T-403: Impact of Dose Reduction for Simulation CT On Radiation Therapy Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Q; Shah, P; Li, S

Purpose: To investigate the feasibility of applying ALARA principles to current treatment planning CT scans. The study aims to quantitatively verify lower dose scans does not alter treatment planning. Method: Gammex 467 tissue characterization phantom with inserts of 14 different materials was scanned at seven different mA levels (30∼300 mA). CT numbers of different inserts were measured. Auto contouring for bone and lung in treatment planning system (Pinnacle) was used to evaluate the effect of CT number accuracy from treatment planning aspect, on the 30 and 300 mA-scanned images. A head CT scan intended for a 3D whole brain radiationmore » treatment was evaluated. Dose calculations were performed on normal scanned images using clinical protocol (120 kVP, Smart mA, maximum 291 mA), and the images with added simulating noise mimicking a 70 mA scan. Plan parameters including isocenter, beam arrangements, block shapes, dose grid size and resolution, and prescriptions were kept the same for these two plans. The calculated monitor units (MUs) for these two plans were compared. Results: No significant degradation of CT number accuracy was found at lower dose levels from both the phantom scans, and the patient images with added noise. The CT numbers kept consistent when mA is higher than 60 mA. The auto contoured volumes for lung and cortical bone show 0.3% and 0.12% of differences between 30 mA and 300 mA respectively. The two forward plans created on regular and low dose images gave the same calculated MU, and 98.3% of points having <1% of dose difference. Conclusion: Both phantom and patient studies quantitatively verified low dose CT provides similar quality for treatment planning at 20–25% of regular scan dose. Therefore, there is the potential to optimize simulation CT scan protocol to fulfil the ALARA principle and limit unnecessary radiation exposure to non-targeted tissues.« less

SU-E-J-270: Repeated 18F-FDG PET/CTs Based Feature Analysis for the Predication of Anal Cancer Recurrence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J; Chuong, M; Choi, W

Purpose: To identify PET/CT based imaging predictors of anal cancer recurrence and evaluate baseline vs. mid-treatment vs. post-treatment PET/CT scans in the tumor recurrence prediction. Methods: FDG-PET/CT scans were obtained at baseline, during chemoradiotherapy (CRT, midtreatment), and after CRT (post-treatment) in 17 patients of anal cancer. Four patients had tumor recurrence. For each patient, the mid-treatment and post-treatment scans were respectively aligned to the baseline scan by a rigid registration followed by a deformable registration. PET/CT image features were computed within the manually delineated tumor volume of each scan to characterize the intensity histogram, spatial patterns (texture), and shape ofmore » the tumors, as well as the changes of these features resulting from CRT. A total of 335 image features were extracted. An Exact Logistic Regression model was employed to analyze these PET/CT image features in order to identify potential predictors for tumor recurrence. Results: Eleven potential predictors of cancer recurrence were identified with p < 0.10, including five shape features, five statistical texture features, and one CT intensity histogram feature. Six features were indentified from posttreatment scans, 3 from mid-treatment scans, and 2 from baseline scans. These features indicated that there were differences in shape, intensity, and spatial pattern between tumors with and without recurrence. Recurrent tumors tended to have more compact shape (higher roundness and lower elongation) and larger intensity difference between baseline and follow-up scans, compared to non-recurrent tumors. Conclusion: PET/CT based anal cancer recurrence predictors were identified. The post-CRT PET/CT is the most important scan for the prediction of cancer recurrence. The baseline and mid-CRT PET/CT also showed value in the prediction and would be more useful for the predication of tumor recurrence in early stage of CRT. This work was supported in part by the National Cancer Institute Grant R01CA172638.« less

CT and MR findings in synovial chondromatosis of the temporo-mandibular joint: our experience and review of literature.

PubMed

Testaverde, Lorenzo; Perrone, Anna; Caporali, Laura; Ermini, Antonella; Izzo, Luciano; D'Angeli, Ilaria; Impara, Luca; Mazza, Dario; Izzo, Paolo; Marini, Mario

2011-06-01

To compare Computed Tomography (CT) and Magnetic Resonance (MR) features and their diagnostic potential in the assessment of Synovial Chondromatosis (SC) of the Temporo-Mandibular Joint (TMJ). Eight patients with symptoms and signs compatible with dysfunctional disorders of the TMJ underwent CT and MR scan. We considered the following parameters: soft tissue involvement (disk included), osteostructural alterations of the joints, loose bodies and intra-articular fluid. These parameters were evaluated separately by two radiologists with a "double blinded method" and then, after agreement, definitive assessment of the parameters was given. CT and MR findings were compared. Histopathological results showed metaplastic synovia in all patients and therefore confirmed diagnosis of SC. MR resulted better than CT in the evaluation of all parameters except the osteostructural alterations of the joints, estimated with more accuracy by CT scan. CT scan is excellent to define bony surfaces of the articular joints and flogistic tissue but it fails in the detection of loose bodies when these are not yet calcified. MR scan therefore is the gold standard when SC is suspected since it can visualize loose bodies at early stage and also evaluate disk condition and eventual extra-articular tissues involvement. The use of T2-weighted images and contrast medium allows identifying intra-articular fluid, estimating its entity and discriminating from sinovial tissue. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

Adaptive iterative dose reduction (AIDR) 3D in low dose CT abdomen-pelvis: Effects on image quality and radiation exposure

NASA Astrophysics Data System (ADS)

Ang, W. C.; Hashim, S.; Karim, M. K. A.; Bahruddin, N. A.; Salehhon, N.; Musa, Y.

2017-05-01

The widespread use of computed tomography (CT) has increased the medical radiation exposure and cancer risk. We aimed to evaluate the impact of AIDR 3D in CT abdomen-pelvic examinations based on image quality and radiation dose in low dose (LD) setting compared to standard dose (STD) with filtered back projection (FBP) reconstruction. We retrospectively reviewed the images of 40 patients who underwent CT abdomen-pelvic using a 80 slice CT scanner. Group 1 patients (n=20, mean age 41 ± 17 years) were performed at LD with AIDR 3D reconstruction and Group 2 patients (n=20, mean age 52 ± 21 years) were scanned with STD using FBP reconstruction. Objective image noise was assessed by region of interest (ROI) measurements in the liver and aorta as standard deviation (SD) of the attenuation value (Hounsfield Unit, HU) while subjective image quality was evaluated by two radiologists. Statistical analysis was used to compare the scan length, CT dose index volume (CTDIvol) and image quality of both patient groups. Although both groups have similar mean scan length, the CTDIvol significantly decreased by 38% in LD CT compared to STD CT (p<0.05). Objective and subjective image quality were statistically improved with AIDR 3D (p<0.05). In conclusion, AIDR 3D enables significant dose reduction of 38% with superior image quality in LD CT abdomen-pelvis.

Arthroscopic and 3D CT Scan Evaluation of Femoral Footprint of the Anterior Cruciate Ligament in Chronic ACL Deficient Knees.

PubMed

Das, Anupam; Yadav, C S; Gamanagatti, Shivanand; Pandey, R M; Mittal, Ravi

2018-06-13

The outcome of single-bundle anterior cruciate ligament (ACL) reconstruction depends largely on the anatomic placement of bone tunnel. The lateral intercondylar ridge (LIR) and bifurcate ridge (BR) are useful bony landmarks for femoral tunnel placement. The purpose of our study was to compare the bony landmarks of ACL footprint on femur by three-dimensional computed tomography (3D CT) scan and arthroscopy in chronic ACL-deficient knees. Fifty patients above 18 years of age who were diagnosed of having ACL tear were selected for the study. All the cases were more than 6 months old since the injury. Preoperative 3D CT scan of the affected knee was obtained for each of them. They underwent single-bundle anatomic ACL reconstruction. Measurements were done on the preoperative 3D CT and arthroscopy to quantify the position of the LIR and BR. The proximodistal distance of lateral femoral condyle was 21.41+/-2.5 mm on CT scan and 22.02+/-2.02 mm on arthroscopy. On preoperative 3D CT scan, the midpoint of the LIR was found to be located at a mean distance of 11.17±2.11 mm from the proximal margin of the lateral femoral condyle. On arthroscopy, it was at 10.18+/-1.52 mm from the proximal margin the lateral femoral condyle. The "bifurcate ridge"(BR) was not visible in any of the cases during arthroscopy or CT scan. We concluded that LIR is an easily identifiable bony landmark on arthroscopy in all cases. It can also be identified on CT scans. BR is not identified both on arthroscopy and CT scans in chronic ACL tears. The arthroscopic measurements of bony landmarks are quite close to those of CT scan. Midpoint of LIR is at 52.185% of the proximodistal distance on CT scan evaluation and it is at 46.21% on arthroscopic evaluation. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Pediatric Emergency CT Scans at a Children's Hospital and at Community Hospitals: Radiation Technical Factors Are an Important Source of Radiation Exposure.

PubMed

Agarwal, Saurabh; Jokerst, Clinton; Siegel, Marilyn J; Hildebolt, Charles

2015-08-01

This article compares the technical factors-in particular, tube current and voltage-and the resultant exposure to radiation associated with CT examinations performed at a children's hospital and at more general community hospital emergency departments (EDs). CT scans obtained at community hospital EDs were retrospectively reviewed and compared with CT scans obtained at a children's hospital, to assess differences in kilovoltage, tube current, and volume CT dose index (CTDIvol) used. The number of scans obtained during the contrast-enhanced phase was also assessed. Parametric and nonparametric statistical analyses were used to test differences. A total of 233 body CT examinations were performed at community hospitals, and 287 were performed at a children's hospital. At both types of hospital, the median patient age was 12 years (p = 0.66). Of the body CT scans obtained at community hospitals that focused on the care of adult patients, 194 of 233 (83%) used a tube voltage of 120 kVp, 29 of 233 (12%) used 100 kVp, and two of 233 (< 1%) used 80 kVp. Of the body CT scans obtained at the children's hospital, 121 of 287 (42%) used a tube voltage of 120 kVp, 129 of 287 (45%) used 100 kVp, and 36 of 287 (13%) used 80 kVp. The median tube current was also lower at the children's hospital (110 vs 125 mA) (p < 0.001). At the community hospitals, 11 of 233 studies were multiphasic, whereas at the children's hospital, there were no multiphasic studies. For all CT types, the median CTDIvol was 4.9 mGy (range, 2.5-8.2 mGy) at the children's hospital and 8.6 mGy (range, 6.0-14.4 mGy) at the community hospitals (p < 0.001). The results of this study suggest that a large proportion of children who undergo CT at community hospitals receive relatively higher radiation doses than children who undergo CT at children's hospitals. This finding is related to the higher tube settings (in particular, kilovoltage) used at community hospitals.

Projected cancer risks potentially related to past, current, and future practices in paediatric CT in the United Kingdom, 1990–2020

PubMed Central

Journy, Neige M Y; Lee, Choonsik; Harbron, Richard W; McHugh, Kieran; Pearce, Mark S; Berrington de González, Amy

2017-01-01

Background: To project risks of developing cancer and the number of cases potentially induced by past, current, and future computed tomography (CT) scans performed in the United Kingdom in individuals aged <20 years. Methods: Organ doses were estimated from surveys of individual scan parameters and CT protocols used in the United Kingdom. Frequencies of scans were estimated from the NHS Diagnostic Imaging Dataset. Excess lifetime risks (ELRs) of radiation-related cancer were calculated as cumulative lifetime risks, accounting for survival probabilities, using the RadRAT risk assessment tool. Results: In 2000–2008, ELRs ranged from 0.3 to 1 per 1000 head scans and 1 to 5 per 1000 non-head scans. ELRs per scan were reduced by 50–70% in 2000–2008 compared with 1990–1995, subsequent to dose reduction over time. The 130 750 scans performed in 2015 in the United Kingdom were projected to induce 64 (90% uncertainty interval (UI): 38–113) future cancers. Current practices would lead to about 300 (90% UI: 230–680) future cancers induced by scans performed in 2016–2020. Conclusions: Absolute excess risks from single exposures would be low compared with background risks, but even small increases in annual CT rates over the next years would substantially increase the number of potential subsequent cancers. PMID:27824812

Reconstruction of paediatric organ doses from axial CT scans performed in the 1990s - range of doses as input to uncertainty estimates.

PubMed

Olerud, Hilde M; Toft, Benthe; Flatabø, Silje; Jahnen, Andreas; Lee, Choonsik; Thierry-Chef, Isabelle

2016-09-01

To assess the range of doses in paediatric CT scans conducted in the 1990s in Norway as input to an international epidemiology study: the EPI-CT study, http://epi-ct.iarc.fr/ . National Cancer Institute dosimetry system for Computed Tomography (NCICT) program based on pre-calculated organ dose conversion coefficients was used to convert CT Dose Index to organ doses in paediatric CT in the 1990s. Protocols reported from local hospitals in a previous Norwegian CT survey were used as input, presuming these were used without optimization for paediatric patients. Large variations in doses between different scanner models and local scan parameter settings are demonstrated. Small children will receive a factor of 2-3 times higher doses compared with adults if the protocols are not optimized for them. For common CT examinations, the doses to the active bone marrow, breast tissue and brain may have exceeded 30 mGy, 60 mGy and 100 mGy respectively, for the youngest children in the 1990s. The doses children received from non-optimised CT examinations during the 1990s are of such magnitude that they may provide statistically significant effects in the EPI-CT study, but probably do not reflect current practice. • Some organ doses from paediatric CT in the 1990s may have exceeded 100 mGy. • Small children may have received doses 2-3 times higher compared with adults. • Different scanner models varied by a factor of 2-3 in dose to patients. • Different local scan parameter settings gave dose variations of a factor 2-3. • Modern CTs and age-adjusted protocols will give much lower paediatric doses.

MO-E-17A-03: Monte Carlo CT Dose Calculation: A Comparison Between Experiment and Simulation Using ARCHER-CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, T; Du, X; Su, L

2014-06-15

Purpose: To compare the CT doses derived from the experiments and GPU-based Monte Carlo (MC) simulations, using a human cadaver and ATOM phantom. Methods: The cadaver of an 88-year old male and the ATOM phantom were scanned by a GE LightSpeed Pro 16 MDCT. For the cadaver study, the Thimble chambers (Model 10×5−0.6CT and 10×6−0.6CT) were used to measure the absorbed dose in different deep and superficial organs. Whole-body scans were first performed to construct a complete image database for MC simulations. Abdomen/pelvis helical scans were then conducted using 120/100 kVps, 300 mAs and a pitch factor of 1.375:1. Formore » the ATOM phantom study, the OSL dosimeters were used and helical scans were performed using 120 kVp and x, y, z tube current modulation (TCM). For the MC simulations, sufficient particles were run in both cases such that the statistical errors of the results by ARCHER-CT were limited to 1%. Results: For the human cadaver scan, the doses to the stomach, liver, colon, left kidney, pancreas and urinary bladder were compared. The difference between experiments and simulations was within 19% for the 120 kVp and 25% for the 100 kVp. For the ATOM phantom scan, the doses to the lung, thyroid, esophagus, heart, stomach, liver, spleen, kidneys and thymus were compared. The difference was 39.2% for the esophagus, and within 16% for all other organs. Conclusion: In this study the experimental and simulated CT doses were compared. Their difference is primarily attributed to the systematic errors of the MC simulations, including the accuracy of the bowtie filter modeling, and the algorithm to generate voxelized phantom from DICOM images. The experimental error is considered small and may arise from the dosimeters. R01 grant (R01EB015478) from National Institute of Biomedical Imaging and Bioengineering.« less

Analysis of patient CT dose data using virtualdose

NASA Astrophysics Data System (ADS)

Bennett, Richard

X-ray computer tomography has many benefits to medical and research applications. Recently, over the last decade CT has had a large increase in usage in hospitals and medical diagnosis. In pediatric care, from 2000 to 2006, abdominal CT scans increased by 49 % and chest CT by 425 % in the emergency room (Broder 2007). Enormous amounts of effort have been performed across multiple academic and government groups to determine an accurate measure of organ dose to patients who undergo a CT scan due to the inherent risks with ionizing radiation. Considering these intrinsic risks, CT dose estimating software becomes a necessary tool that health care providers and radiologist must use to determine many metrics to base the risks versus rewards of having an x-ray CT scan. This thesis models the resultant organ dose as body mass increases for patients with all other related scan parameters fixed. In addition to this,this thesis compares a modern dose estimating software, VirtualDose CT to two other programs, CT-Expo and ImPACT CT. The comparison shows how the software's theoretical basis and the phantom they use to represent the human body affect the range of results in organ dose. CT-Expo and ImPACT CT dose estimating software uses a different model for anatomical representation of the organs in the human body and the results show how that approach dramatically changes the outcome. The results categorizes four datasets as compared to the three software types where the appropriate phantom was available. Modeling was done to simulate chest abdominal pelvis scans and whole body scans. Organ dose difference versus body mass index shows as body mass index (BMI) ranges from 23.5 kg/m 2 to 45 kg/m2 the amount of organ dose also trends a percent change from -4.58 to -176.19 %. Comparing organ dose difference with increasing x-ray tube potential from 120 kVp to 140 kVp the percent change in organ dose increases from 55 % to 65 % across all phantoms. In comparing VirtualDose to CT-Expo for organ dose difference versus age, male phantoms show percent difference of -19 % to 25 % for various organs minus bone surface and breast tissues results. Finally, for organ dose difference across all software for average adult phantom the results range from -45 % to 6 % in the comparison of ImPACT CT to VirtualDose and -27 % to 66 % for the comparison of CT-Expo to VirtualDose. In the comparison for increased BMI (done only in VirtualDose), results show that with all other parameters fixed, the organ dose goes down as BMI increases, which is due to the increase in adipose tissue and bulk of the patient model. The range of results when comparing all the three softwares have a wide range, in some cases greater than 150 %, it is evident that using a different anatomical basis for the human phantom and the theoretical basis for the dose estimation will cause fluctuation in the results. Therefore, choosing the software with the most accurate human phantom will provide a closer range to the true dose to the organ.

Radiography versus computed tomography for displacement assessment in calcaneal fractures.

PubMed

Ogawa, Brent K; Charlton, Timothy P; Thordarson, David B

2009-10-01

Coronal computed tomography (CT) scans are commonly used in fracture classification systems for calcaneus fractures. However, they may not accurately reflect the amount of fracture displacement. The purpose of this paper was to determine whether lateral radiographs provide superior assessment of the displacement of the posterior facet compared to coronal CT scans. Lateral radiographs of calcaneus fractures were compared with CT coronal images of the posterior facet in 30 displaced intra-articular calcaneus fractures. The average patient age was 39 years old. Using a Picture Archiving and Communication System (PACS), measurements were obtained to quantify the amount of displacement on the lateral radiograph and compared with the amount of depression on corresponding coronal CT scans. On lateral radiographs, the angle of the depressed portion of the posterior facet relative to the undersurface of the calcaneus averaged 28.2 degrees; Bohler's angle averaged 12.7 degrees. These numbers were poorly correlated (r = 0.25). In corresponding CT images from posterior to anterior, the difference in the amount of displacement of the lateral portion of the displaced articular facet versus the nondisplaced medial, constant fragment, was minimal and consistently underestimated the amount of displacement. Underestimation of the amount of depression and rotation of the posterior facet fragment was seen on the coronal CT scan. We attribute this finding to the combined rotation and depression of the posterior facet which may not be measured accurately with the typical semicoronal CT orientation. While sagittal reconstructed images would show this depression better, if they are unavailable we recommend using lateral radiographs to better gauge the amount of fracture displacement.

Algorithm-enabled partial-angular-scan configurations for dual-energy CT.

PubMed

Chen, Buxin; Zhang, Zheng; Xia, Dan; Sidky, Emil Y; Pan, Xiaochuan

2018-05-01

We seek to investigate an optimization-based one-step method for image reconstruction that explicitly compensates for nonlinear spectral response (i.e., the beam-hardening effect) in dual-energy CT, to investigate the feasibility of the one-step method for enabling two dual-energy partial-angular-scan configurations, referred to as the short- and half-scan configurations, on standard CT scanners without involving additional hardware, and to investigate the potential of the short- and half-scan configurations in reducing imaging dose and scan time in a single-kVp-switch full-scan configuration in which two full rotations are made for collection of dual-energy data. We use the one-step method to reconstruct images directly from dual-energy data through solving a nonconvex optimization program that specifies the images to be reconstructed in dual-energy CT. Dual-energy full-scan data are generated from numerical phantoms and collected from physical phantoms with the standard single-kVp-switch full-scan configuration, whereas dual-energy short- and half-scan data are extracted from the corresponding full-scan data. Besides visual inspection and profile-plot comparison, the reconstructed images are analyzed also in quantitative studies based upon tasks of linear-attenuation-coefficient and material-concentration estimation and of material differentiation. Following the performance of a computer-simulation study to verify that the one-step method can reconstruct numerically accurately basis and monochromatic images of numerical phantoms, we reconstruct basis and monochromatic images by using the one-step method from real data of physical phantoms collected with the full-, short-, and half-scan configurations. Subjective inspection based upon visualization and profile-plot comparison reveals that monochromatic images, which are used often in practical applications, reconstructed from the full-, short-, and half-scan data are largely visually comparable except for some differences in texture details. Moreover, quantitative studies based upon tasks of linear-attenuation-coefficient and material-concentration estimation and of material differentiation indicate that the short- and half-scan configurations yield results in close agreement with the ground-truth information and that of the full-scan configuration. The one-step method considered can compensate effectively for the nonlinear spectral response in full- and partial-angular-scan dual-energy CT. It can be exploited for enabling partial-angular-scan configurations on standard CT scanner without involving additional hardware. Visual inspection and quantitative studies reveal that, with the one-step method, partial-angular-scan configurations considered can perform at a level comparable to that of the full-scan configuration, thus suggesting the potential of the two partial-angular-scan configurations in reducing imaging dose and scan time in the standard single-kVp-switch full-scan CT in which two full rotations are performed. The work also yields insights into the investigation and design of other nonstandard scan configurations of potential practical significance in dual-energy CT. © 2018 American Association of Physicists in Medicine.

Comparison of computed tomography and complex motion tomography in the evaluation of cholesteatoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaffer, K.A.

1984-08-01

High-resolution axial and coronal computed tomographic (CT) scans were compared with coronal and sagittal complex motion tomograms in patients with suspected middle ear cholesteatomas. Information on CT scans equaled or exceeded that on conventional complex motion tomograms in 16 of 17 patients, and in 11 it provided additional information. Soft-tissue resolution was superior with CT. In 14 patients who underwent surgery, CT provided information that was valuable to the surgeon. On the basis of this study, high-resolution CT is recommended as the preferred method for evaluating most patients with cholesteatomas of the temporal bone.

A new contrast agent for radiological and dissection studies of the arterial network of anatomic specimens.

PubMed

Bulla, A; Casoli, C; Farace, F; Mazzarello, V; De Luca, L; Rubino, C; Montella, A

2014-01-01

The aim of the present study is to propose a new contrast agent that can be easily applied both to CT and dissection studies to replace lead oxide based formulas for comparative anatomical analyses of the vascularisation of cadaveric specimens. The infusion material was an epoxy resin, especially modified by the addition of barium sulphate to enhance its radiopacity. The final copolymer was toxicologically safe. To test the properties of the new material, several cadaveric limb injections were performed. The injected specimens were both CT scanned to perform 3D vascular reconstructions and dissected by anatomical planes. There was a perfect correspondence between the image studies and the dissections: even the smallest arteries on CT scan can be identified on the specimen and vice versa. The properties of the epoxy allowed an easy dissection of the vessels. The new imaging techniques available today, such as CT scan, can evaluate the vascular anatomy in high detail and 3D. This new contrast agent may help realising detailed vascular studies comparing CT scan results with anatomical dissections. Moreover, it may be useful for teaching surgical skills in the field of plastic surgery.

Influence of anatomical location on CT numbers in cone beam computed tomography.

PubMed

Oliveira, Matheus L; Tosoni, Guilherme M; Lindsey, David H; Mendoza, Kristopher; Tetradis, Sotirios; Mallya, Sanjay M

2013-04-01

To assess the influence of anatomical location on computed tomography (CT) numbers in mid- and full field of view (FOV) cone beam computed tomography (CBCT) scans. Polypropylene tubes with varying concentrations of dipotassium hydrogen phosphate (K₂HPO₄) solutions (50-1200 mg/mL) were imaged within the incisor, premolar, and molar dental sockets of a human skull phantom. CBCT scans were acquired using the NewTom 3G and NewTom 5G units. The CT numbers of the K₂HPO₄ phantoms were measured, and the relationship between CT numbers and K₂HPO₄ concentration was examined. The measured CT numbers of the K₂HPO₄ phantoms were compared between anatomical sites. At all six anatomical locations, there was a strong linear relationship between CT numbers and K₂HPO₄ concentration (R(2)>0.93). However, the absolute CT numbers varied considerably with the anatomical location. The relationship between CT numbers and object density is not uniform through the dental arch on CBCT scans. Copyright © 2013 Elsevier Inc. All rights reserved.

SU-F-I-40: Impact of Scan Length On Patient Dose in Abdomen/pelvis CT Diagnosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, I; Song, J; Kim, K

Purpose: To analysis the impact of scan length on patient doses in abdomen/pelvis CT diagnosis of each hospital. Methods: Scan length of 7 hospitals from abdomen/pelvis CT diagnosis was surveyed in Korea. Surveyed scan lengths were additional distance above diaphragm and distance below pubic symphysis except for standard scan range between diaphragm and pubic symphysis. Patient dose was estimated for adult male and female according to scan length of each hospital. CT-Expo was used to estimate the patient dose under identical equipment settings (120 kVp, 100 mAs, 10 mm collimation width, etc.) except scan length. Effective dose was calculated bymore » using tissue weighting factor of ICRP 103 recommendation. Increase rate of effective dose was calculated comparing with effective dose of standard scan range Results: Scan lengths of abdomen/pelvis CT diagnosis of each hospital were different. Also effective dose was increased with increasing the scan length. Generally increasing the distance above diaphragm caused increase of effective dose of male and female, but increasing the distance below pubic symphysis caused increase of effective dose of male. Conclusion: We estimated the patient dose according to scan length of each hospital in abdomen/pelvis CT diagnosis. Effective dose was increased by increasing the scan length because dose of organs with high tissue weighting factor such as lung, breast, testis were increased. Scan length is important factor on patient dose in CT diagnosis. If radiologic technologist interested in patient dose, decreasing the unnecessary scan length will decrease the risk of patients from radiation. This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI13C0004).« less

Accuracy and Radiation Dose Reduction of Limited-Range CT in the Evaluation of Acute Appendicitis in Pediatric Patients.

PubMed

Jin, Michael; Sanchez, Thomas R; Lamba, Ramit; Fananapazir, Ghaneh; Corwin, Michael T

2017-09-01

The purpose of this article is to determine the accuracy and radiation dose reduction of limited-range CT prescribed from the top of L2 to the top of the pubic symphysis in children with suspected acute appendicitis. We performed a retrospective study of 210 consecutive pediatric patients from December 11, 2012, through December 11, 2014, who underwent abdominopelvic CT for suspected acute appendicitis. Two radiologists independently reviewed the theoretic limited scans from the superior L2 vertebral body to the top of the pubic symphysis, to assess for visualization of the appendix, acute appendicitis, alternative diagnoses, and incidental findings. Separately, the same parameters were assessed on the full scan by the same two reviewers. Whole-body effective doses were determined for the full- and limited-range scans and were compared using the paired t test. The appendix or entire cecum was visualized on the limited scan in all cases, and no cases of acute appendicitis were missed on the simulated limited scan compared with the full scan. Two alternative diagnoses were missed with the limited scan: one case of hydronephrosis and one of acute acalculous cholecystitis. The mean effective dose for the original scan was 5.6 mSv and that for the simulated limited scan was 3.0 mSv, resulting in a dose reduction of 46.4% (p < 0.001). A limited-range CT examination performed from the top of L2 to the top of the pubic symphysis is as accurate as a full-range abdominopelvic CT in evaluating pediatric patients with suspected appendicitis and reduces the dose by approximately 46%.

The utility of computed tomography in the management of fever and neutropenia in pediatric oncology.

PubMed

Rao, Avani D; Sugar, Elizabeth A; Barrett, Neil; Mahesh, Mahadevappa; Arceci, Robert J

2015-10-01

Despite the frequent use and radiation exposure of computed tomography (CT) scans, there is little information on patterns of CT use and their utility in the management of pediatric patients with fever and neutropenia (FN). We examined the contribution of either the commonly employed pan-CT (multiple anatomical locations) or targeted CT (single location) scanning to identify possible infectious etiologies in this challenging clinical scenario. Procedure Pediatric patients with an underlying malignancy admitted for fever (temperature ≥ 38.3 °C) and an absolute neutrophil count <500 cells/μL from 2003-2009 were included. Risk factors associated with utilization, results, and effects on clinical management of CT scans were identified. Results Charts for 635 admissions for FN from 263 patients were reviewed. Overall, 139 (22%) admissions (93 individuals) had at least one scan. Of 188 scans, 103 (55%) were pan-scans. Changes in management were most strongly associated with the identification of evidence consistent with infection (OR = 12.64, 95% CI: 5.05-31.60, P < 0.001). Seventy-eight (41%) of all CT scans led to a change in clinical management, most commonly relating to use of antibiotic (N = 41, 53%) or antifungal/antiviral medications (N = 33, 42%). The odds of a change in clinical management did not differ for those receiving a pan-scan compared to those receiving a targeted scan (OR = 1.23; 95% CI, 0.61-2.46; P = 0.57). Conclusions When CT is clinically indicated, it is important for clinicians to strongly consider utilizing a targeted scan to reduce radiation exposure to patients as well as to decrease costs without compromising care. © 2015 Wiley Periodicals, Inc.

Reducing Head CT Use for Children With Head Injuries in a Community Emergency Department.

PubMed

Jennings, Rebecca M; Burtner, Jennifer J; Pellicer, Joseph F; Nair, Deepthi K; Bradford, Miranda C; Shaffer, Michele; Uspal, Neil G; Tieder, Joel S

2017-04-01

Clinical decision rules have reduced use of computed tomography (CT) to evaluate minor pediatric head injury in pediatric emergency departments (EDs). CT use remains high in community EDs, where the majority of children seek medical care. We sought to reduce the rate of CT scans used to evaluate pediatric head injury from 29% to 20% in a community ED. We evaluated a quality improvement (QI) project in a community ED aimed at decreasing the use of head CT scans in children by implementing a validated head trauma prediction rule for traumatic brain injury. A multidisciplinary team identified key drivers of CT use and implemented decision aids to improve the use of prediction rules. The team identified and mitigated barriers. An affiliated children's hospital offered Maintenance of Certification credit and QI coaching to participants. We used statistical process control charts to evaluate the effect of the intervention on monthly CT scan rates and performed a Wald test of equivalence to compare preintervention and postintervention CT scan proportions. The baseline period (February 2013-July 2014) included 695 patients with a CT scan rate of 29.2% (95% confidence interval, 25.8%-32.6%). The postintervention period (August 2014-October 2015) included 651 patients with a CT scan rate of 17.4% (95% confidence interval, 14.5%-20.2%, P < .01). Barriers included targeting providers with variable pediatric experience and parental imaging expectations. We demonstrate that a Maintenance of Certification QI project sponsored by a children's hospital can facilitate evidence-based pediatric care and decrease the rate of unnecessary CT use in a community setting. Copyright © 2017 by the American Academy of Pediatrics.

Spiral computed tomography phase-space source model in the BEAMnrc/EGSnrc Monte Carlo system: implementation and validation

NASA Astrophysics Data System (ADS)

Kim, Sangroh; Yoshizumi, Terry T.; Yin, Fang-Fang; Chetty, Indrin J.

2013-04-01

Currently, the BEAMnrc/EGSnrc Monte Carlo (MC) system does not provide a spiral CT source model for the simulation of spiral CT scanning. We developed and validated a spiral CT phase-space source model in the BEAMnrc/EGSnrc system. The spiral phase-space source model was implemented in the DOSXYZnrc user code of the BEAMnrc/EGSnrc system by analyzing the geometry of spiral CT scan—scan range, initial angle, rotational direction, pitch, slice thickness, etc. Table movement was simulated by changing the coordinates of the isocenter as a function of beam angles. Some parameters such as pitch, slice thickness and translation per rotation were also incorporated into the model to make the new phase-space source model, designed specifically for spiral CT scan simulations. The source model was hard-coded by modifying the ‘ISource = 8: Phase-Space Source Incident from Multiple Directions’ in the srcxyznrc.mortran and dosxyznrc.mortran files in the DOSXYZnrc user code. In order to verify the implementation, spiral CT scans were simulated in a CT dose index phantom using the validated x-ray tube model of a commercial CT simulator for both the original multi-direction source (ISOURCE = 8) and the new phase-space source model in the DOSXYZnrc system. Then the acquired 2D and 3D dose distributions were analyzed with respect to the input parameters for various pitch values. In addition, surface-dose profiles were also measured for a patient CT scan protocol using radiochromic film and were compared with the MC simulations. The new phase-space source model was found to simulate the spiral CT scanning in a single simulation run accurately. It also produced the equivalent dose distribution of the ISOURCE = 8 model for the same CT scan parameters. The MC-simulated surface profiles were well matched to the film measurement overall within 10%. The new spiral CT phase-space source model was implemented in the BEAMnrc/EGSnrc system. This work will be beneficial in estimating the spiral CT scan dose in the BEAMnrc/EGSnrc system.

Normal cross-sectional anatomy of the bovine digit: comparison of computed tomography and limb anatomy.

PubMed

Raji, A R; Sardari, K; Mohammadi, H R

2008-06-01

The purpose of this study was to define the structures of the digits and hoof in Holstein dairy cattle by using computed tomography scan (CT scan). Transverse, sagittal and dorsoplantar CT images of two isolated cattle cadaver digits were obtained using a Siemens ARTX2 Somatom. The CT images were compared to corresponding frozen cross-sections. Relevant anatomical structures were identified and labelled at each level. The CT images provided anatomical detail of the digits and hoof in Holstein dairy cattle. Transversal images provided excellent depiction of anatomical structures when compared to corresponding frozen cross-sections. The information presented in this paper would serve as an initial reference to the evaluation of CT images of the digits and hoof in Holstein dairy cattle.

Patch-based generation of a pseudo CT from conventional MRI sequences for MRI-only radiotherapy of the brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreasen, Daniel, E-mail: dana@dtu.dk; Van Leemput, Koen; Hansen, Rasmus H.

Purpose: In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to electron density. To solve the task, voxel-based or atlas-based models have typically been used. The voxel-based models require a specialized dual ultrashort echo time MRI sequence for bone visualization and the atlas-based models require deformable registrations of conventional MRI scans. In this study, we investigate the potential of amore » patch-based method for creating a pCT based on conventional T{sub 1}-weighted MRI scans without using deformable registrations. We compare this method against two state-of-the-art methods within the voxel-based and atlas-based categories. Methods: The data consisted of CT and MRI scans of five cranial RT patients. To compare the performance of the different methods, a nested cross validation was done to find optimal model parameters for all the methods. Voxel-wise and geometric evaluations of the pCTs were done. Furthermore, a radiologic evaluation based on water equivalent path lengths was carried out, comparing the upper hemisphere of the head in the pCT and the real CT. Finally, the dosimetric accuracy was tested and compared for a photon treatment plan. Results: The pCTs produced with the patch-based method had the best voxel-wise, geometric, and radiologic agreement with the real CT, closely followed by the atlas-based method. In terms of the dosimetric accuracy, the patch-based method had average deviations of less than 0.5% in measures related to target coverage. Conclusions: We showed that a patch-based method could generate an accurate pCT based on conventional T{sub 1}-weighted MRI sequences and without deformable registrations. In our evaluations, the method performed better than existing voxel-based and atlas-based methods and showed a promising potential for RT of the brain based only on MRI.« less

The presurgical workup before third molar surgery: how much is enough?

PubMed

Better, Hadar; Abramovitz, Itzhak; Shlomi, Biniamin; Kahn, Adrian; Levy, Yaakov; Shaham, Amit; Chaushu, Gavriel

2004-06-01

We sought to assess the indications for patient referral for computed tomography (CT) scan before third molar extraction. The influence of the data obtained from the CT scans on the surgical outcome and morbidity was also evaluated. There were 189 patients in the study (120 females and 69 males). Sixty-five patients were referred to receive CT and formed the study group. The remaining patients were included in the control group. There were no statistically significant differences between the groups with regard to demographic data and tooth and root angulations. Indications for tooth extraction such as pain, swelling, pericoronitis, caries, endodontic problems, pathology, and prosthetic considerations were similar. The proximity of the tooth root to the inferior alveolar canal was the only statistically significant difference between the 2 groups (P <.001). The treatment plan outcomes for extraction, surgical extraction, and follow-up were comparable. The surgeon changed the initial decision from "surgical extraction" to "follow-up" in only 1 case after CT scan. Within the limits of the present study, it can be concluded that the main reason for CT scan referral is the proximity of the third molar root to the inferior alveolar canal (<1 mm). The data obtained from the CT scan had minimal effect on the final surgical outcome. The routine use of CT scan in cases of third molar extractions cannot be recommended.

Bicuspid aortic valves: diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT.

PubMed

Murphy, David J; McEvoy, Sinead H; Iyengar, Sri; Feuchtner, Gudrun; Cury, Ricardo C; Roobottom, Carl; Baumueller, Stephan; Alkadhi, Hatem; Dodd, Jonathan D

2014-08-01

To assess the diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT for bicuspid aortic valves. The standard axial chest CT scans of 20 patients with known bicuspid aortic valves were blindly, randomly analyzed for (i) the appearance of the valve cusps, (ii) the largest aortic sinus area, (iii) the longest aortic cusp length, (iv) the thickest aortic valve cusp and (v) valve calcification. A second blinded reader independently analyzed the appearance of the valve cusps. Forty-two age- and sex-matched patients with known tricuspid aortic valves were used as controls. Retrospectively ECG-gated cardiac CT multiphase reconstructions of the aortic valve were used as the gold-standard. Fourteen (21%) scans were scored as unevaluable (7 bicuspid, 7 tricuspid). Of the remainder, there were 13 evaluable bicuspid valves, ten of which showed an aortic valve line sign, while the remaining three showed a normal Mercedes-Benz appearance owing to fused valve cusps. The 35 evaluable tricuspid aortic valves all showed a normal Mercedes-Benz appearance (P=0.001). Kappa analysis=0.62 indicating good interobserver agreement for the aortic valve cusp appearance. Aortic sinus areas, aortic cusp lengths and aortic cusp thicknesses of ≥ 3.8 cm(2), 3.2 cm and 1.6mm respectively on standard axial chest CT best distinguished bicuspid from tricuspid aortic valves (P<0.0001 for all). Of evaluable scans, the sensitivity, specificity, positive and negative predictive values of standard axial chest CT in diagnosing bicuspid aortic valves was 77% (CI 0.54-1.0), 100%, 100% and 70% respectively. The aortic valve is evaluable in approximately 80% of standard chest 64-slice CT scans. Bicuspid aortic valves may be diagnosed on evaluable scans with good diagnostic accuracy. An aortic valve line sign, enlarged aortic sinuses and elongated, thickened valve cusps are specific CT features. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

[Mobile CT: technical aspects of prehospital stroke imaging before intravenous thrombolysis].

PubMed

Gierhake, D; Weber, J E; Villringer, K; Ebinger, M; Audebert, H J; Fiebach, J B

2013-01-01

To reduce the time from symptom onset to treatment with tissue plasminogen activator (tPA) in ischemic stroke, an ambulance was equipped with a CT scanner. We analyzed process and image quality of CT scanning during the pilot study regarding image quality and safety issues. The pilot study of a stroke emergency mobile unit (STEMO) ran over a period of 12 weeks on 5 weekdays from 7a.m. to 6:30 p.m. A teleradiological service for the justifying indication and reporting was established. The radiographer was responsible for the performance of the CT scan on the ambulance. 64 cranial CT scans and 1 intracranial CT angiography were performed. We compared times from ambulance alarm to treatment decision (time of last brain scan) with a cohort of 50 consecutive tPA treatments before implementation of STEMO. 62 (95%) of the 65 scans performed had sufficient quality for reading. Technical quality was not optimal in 45 cases (69%) mainly caused by suboptimal positioning of patient or eye lens protection. Motion artefacts were observed in 8 exams (12%). No safety issues occurred for team or patients. 23 patients were treated with thrombolysis. Time from alarm to last CT scan was 18 minutes shorter than in the tPA cohort before STEMO implementation. A teleradiological support for primary stroke imaging by CT on-site is feasible, quality-wise of diagnostic value and has not raised safety issues. © Georg Thieme Verlag KG Stuttgart · New York.

Thoracic-abdominal imaging with a novel dual-layer spectral detector CT: intra-individual comparison of image quality and radiation dose with 128-row single-energy acquisition.

PubMed

Haneder, Stefan; Siedek, Florian; Doerner, Jonas; Pahn, Gregor; Grosse Hokamp, Nils; Maintz, David; Wybranski, Christian

2018-01-01

Background A novel, multi-energy, dual-layer spectral detector computed tomography (SDCT) is commercially available now with the vendor's claim that it yields the same or better quality of polychromatic, conventional CT images like modern single-energy CT scanners without any radiation dose penalty. Purpose To intra-individually compare the quality of conventional polychromatic CT images acquired with a dual-layer spectral detector (SDCT) and the latest generation 128-row single-energy-detector (CT128) from the same manufacturer. Material and Methods Fifty patients underwent portal-venous phase, thoracic-abdominal CT scans with the SDCT and prior CT128 imaging. The SDCT scanning protocol was adapted to yield a similar estimated dose length product (DLP) as the CT128. Patient dose optimization by automatic tube current modulation and CT image reconstruction with a state-of-the-art iterative algorithm were identical on both scanners. CT image contrast-to-noise ratio (CNR) was compared between the SDCT and CT128 in different anatomic structures. Image quality and noise were assessed independently by two readers with 5-point-Likert-scales. Volume CT dose index (CTDI vol ), and DLP were recorded and normalized to 68 cm acquisition length (DLP 68 ). Results The SDCT yielded higher mean CNR values of 30.0% ± 2.0% (26.4-32.5%) in all anatomic structures ( P < 0.001) and excellent scores for qualitative parameters surpassing the CT128 (all P < 0.0001) with substantial inter-rater agreement (κ ≥ 0.801). Despite adapted scan protocols the SDCT yielded lower values for CTDI vol (-10.1 ± 12.8%), DLP (-13.1 ± 13.9%), and DLP 68 (-15.3 ± 16.9%) than the CT128 (all P < 0.0001). Conclusion The SDCT scanner yielded better CT image quality compared to the CT128 and lower radiation dose parameters.

Variation compensation and analysis on diaphragm curvature analysis for emphysema quantification on whole lung CT scans

NASA Astrophysics Data System (ADS)

Keller, Brad M.; Reeves, Anthony P.; Barr, R. Graham; Yankelevitz, David F.; Henschke, Claudia I.

2010-03-01

CT scans allow for the quantitative evaluation of the anatomical bases of emphysema. Recently, a non-density based geometric measurement of lung diagphragm curvature has been proposed as a method for the quantification of emphysema from CT. This work analyzes variability of diaphragm curvature and evaluates the effectiveness of a compensation methodology for the reduction of this variability as compared to emphysema index. Using a dataset of 43 scan-pairs with less than a 100 day time-interval between scans, we find that the diaphragm curvature had a trend towards lower overall variability over emphysema index (95% CI:-9.7 to + 14.7 vs. -15.8 to +12.0), and that the variation of both measures was reduced after compensation. We conclude that the variation of the new measure can be considered comparable to the established measure and the compensation can reduce the apparent variation of quantitative measures successfully.

Quantification of pleural effusion on CT by simple measurement.

PubMed

Hazlinger, Martin; Ctvrtlik, Filip; Langova, Katerina; Herman, Miroslav

2014-01-01

To find the simplest method for quantifying pleural effusion volume from CT scans. Seventy pleural effusions found on chest CT examination in 50 consecutive adult patients with the presence of free pleural effusion were included. The volume of pleural effusion was calculated from a three-dimensional reconstruction of CT scans. Planar measurements were made on CT scans and their two-dimensional reconstructions in the sagittal plane and at three levels on transversal scans. Individual planar measurements were statistically compared with the detected volume of pleural effusion. Regression equations, averaged absolute difference between observed and predicted values and determination coefficients were found for all measurements and their combinations. A tabular expression of the best single planar measurement was created. The most accurate correlation between the volume and a single planar measurement was found in the dimension measured perpendicular to the parietal pleura on transversal scan with the greatest depth of effusion. Conversion of this measurement to the appropriate volume is possible by regression equation: Volume = 0.365 × b(3) - 4.529 × b(2) + 159.723 × b - 88.377. We devised a simple method of conversion of a single planar measurement on CT scan to the volume of pleural effusion. The tabular expression of our equation can be easily and effectively used in routine practice.

68 Ga-PSMA-PET/CT staging prior to definitive radiation treatment for prostate cancer.

PubMed

Hruby, George; Eade, Thomas; Emmett, Louise; Ho, Bao; Hsiao, Ed; Schembri, Geoff; Guo, Linxin; Kwong, Carolyn; Hunter, Julia; Byrne, Keelan; Kneebone, Andrew

2018-04-16

To explore the utility of prostate specific membrane antigen (PSMA)-positron emission tomography (PET)/computed tomography (CT) in addition to conventional imaging prior to definitive external beam radiation treatment (EBRT) for prostate cancer. All men undergoing PSMA-PET/CT prior to definitive EBRT for intermediate and high-risk prostate cancer were included in our ethics approved prospective database. For each patient, clinical and pathological results, in addition to scan results including site of PSMA positive disease and number of lesions, were recorded. Results of conventional imaging (bone scan, CT and multiparametric magnetic resonance imaging [MRI]) were reviewed and included. One hundred nine men underwent staging PSMA-PET/CT between May 2015 and June 2017; all patients had national comprehensive cancer network (NCCN) intermediate or high-risk prostate cancer and 87% had Gleason score (GS) 4 + 3 or higher. There was positive uptake corresponding to the primary in 108, equivocal in one. All patients with image detected nodal or bony lesions had GS 4 + 3 or more disease. Compared to conventional imaging with bone scan, CT and multiparametric MRI, PSMA-PET/CT upstaged an additional 7 patients (6.4%) from M0 to M1, 16 from N0M0 to N1M0 (14.7%) and downstaged 3 (2.8%) from M1 to M0 disease. PSMA-PET/CT identified the primary in 99% of patients, and altered staging in 21% of men with intermediate or high-risk prostate cancer referred for definitive EBRT compared to CT, bone scan and multiparametric MRI. Following this audit, we recommend the routine use of PSMA-PET/CT prior to EBRT in this patient group. © 2018 John Wiley & Sons Australia, Ltd.

Validation of CBCT for the computation of textural biomarkers

NASA Astrophysics Data System (ADS)

Paniagua, Beatriz; Ruellas, Antonio C.; Benavides, Erika; Marron, Steve; Wolford, Larry; Cevidanes, Lucia

2015-03-01

Osteoarthritis (OA) is associated with significant pain and 42.6% of patients with TMJ disorders present with evidence of TMJ OA. However, OA diagnosis and treatment remain controversial, since there are no clear symptoms of the disease. The subchondral bone in the TMJ is believed to play a major role in the progression of OA. We hypothesize that the textural imaging biomarkers computed in high resolution Conebeam CT (hr- CBCT) and μCT scans are comparable. The purpose of this study is to test the feasibility of computing textural imaging biomarkers in-vivo using hr-CBCT, compared to those computed in μCT scans as our Gold Standard. Specimens of condylar bones obtained from condylectomies were scanned using μCT and hr- CBCT. Nine different textural imaging biomarkers (four co-occurrence features and five run-length features) from each pair of μCT and hr-CBCT were computed and compared. Pearson correlation coefficients were computed to compare textural biomarkers values of μCT and hr-CBCT. Four of the nine computed textural biomarkers showed a strong positive correlation between biomarkers computed in μCT and hr-CBCT. Higher correlations in Energy and Contrast, and in GLN (grey-level non-uniformity) and RLN (run length non-uniformity) indicate quantitative texture features can be computed reliably in hr-CBCT, when compared with μCT. The textural imaging biomarkers computed in-vivo hr-CBCT have captured the structure, patterns, contrast between neighboring regions and uniformity of healthy and/or pathologic subchondral bone. The ability to quantify bone texture non-invasively now makes it possible to evaluate the progression of subchondral bone alterations, in TMJ OA.

Validation of CBCT for the computation of textural biomarkers

PubMed Central

Paniagua, Beatriz; Ruellas, Antonio Carlos; Benavides, Erika; Marron, Steve; Woldford, Larry; Cevidanes, Lucia

2015-01-01

Osteoarthritis (OA) is associated with significant pain and 42.6% of patients with TMJ disorders present with evidence of TMJ OA. However, OA diagnosis and treatment remain controversial, since there are no clear symptoms of the disease. The subchondral bone in the TMJ is believed to play a major role in the progression of OA. We hypothesize that the textural imaging biomarkers computed in high resolution Conebeam CT (hr-CBCT) and μCT scans are comparable. The purpose of this study is to test the feasibility of computing textural imaging biomarkers in-vivo using hr-CBCT, compared to those computed in μCT scans as our Gold Standard. Specimens of condylar bones obtained from condylectomies were scanned using μCT and hr-CBCT. Nine different textural imaging biomarkers (four co-occurrence features and five run-length features) from each pair of μCT and hr-CBCT were computed and compared. Pearson correlation coefficients were computed to compare textural biomarkers values of μCT and hr-CBCT. Four of the nine computed textural biomarkers showed a strong positive correlation between biomarkers computed in μCT and hr-CBCT. Higher correlations in Energy and Contrast, and in GLN (grey-level non-uniformity) and RLN (run length non-uniformity) indicate quantitative texture features can be computed reliably in hr-CBCT, when compared with μCT. The textural imaging biomarkers computed in-vivo hr-CBCT have captured the structure, patterns, contrast between neighboring regions and uniformity of healthy and/or pathologic subchondral bone. The ability to quantify bone texture non-invasively now makes it possible to evaluate the progression of subchondral bone alterations, in TMJ OA. PMID:26085710

Validation of CBCT for the computation of textural biomarkers.

PubMed

Paniagua, Beatriz; Ruellas, Antonio Carlos; Benavides, Erika; Marron, Steve; Woldford, Larry; Cevidanes, Lucia

2015-03-17

Osteoarthritis (OA) is associated with significant pain and 42.6% of patients with TMJ disorders present with evidence of TMJ OA. However, OA diagnosis and treatment remain controversial, since there are no clear symptoms of the disease. The subchondral bone in the TMJ is believed to play a major role in the progression of OA. We hypothesize that the textural imaging biomarkers computed in high resolution Conebeam CT (hr-CBCT) and μCT scans are comparable. The purpose of this study is to test the feasibility of computing textural imaging biomarkers in-vivo using hr-CBCT, compared to those computed in μCT scans as our Gold Standard. Specimens of condylar bones obtained from condylectomies were scanned using μCT and hr-CBCT. Nine different textural imaging biomarkers (four co-occurrence features and five run-length features) from each pair of μCT and hr-CBCT were computed and compared. Pearson correlation coefficients were computed to compare textural biomarkers values of μCT and hr-CBCT. Four of the nine computed textural biomarkers showed a strong positive correlation between biomarkers computed in μCT and hr-CBCT. Higher correlations in Energy and Contrast, and in GLN (grey-level non-uniformity) and RLN (run length non-uniformity) indicate quantitative texture features can be computed reliably in hr-CBCT, when compared with μCT. The textural imaging biomarkers computed in-vivo hr-CBCT have captured the structure, patterns, contrast between neighboring regions and uniformity of healthy and/or pathologic subchondral bone. The ability to quantify bone texture non-invasively now makes it possible to evaluate the progression of subchondral bone alterations, in TMJ OA.

Pretreatment with diphenoxylate hydrochloride/atropine sulfate (Lomotil) does not decrease physiologic bowel FDG activity on PET/CT scans of the abdomen and pelvis.

PubMed

Murphy, Robert; Doerger, Kirk M; Nathan, Mark A; Lowe, Val J

2009-01-01

Physiologic uptake of 2-[(18)F]-fluoro-2-deoxy-D: -glucose (FDG) by bowel can confound positron emission tomography/computed tomography (PET/CT) assessment for abdominal pathology, particularly within the bowel itself. We wished to determine if oral administration of the antimotility agent, Lomotil (5 mg diphenoxylate hydrochloride/0.05 mg atropine sulfate; G.D. Searle and Company, a division of Pfizer), prior to PET/CT scanning would reduce physiologic uptake of FDG by the small bowel and colon (lower gastrointestinal [GI] tract). Patients undergoing PET/CT scans for lymphoma were enrolled in a prospective, randomized, double-blinded study and received either 10 mL water (control group) or 10 mL Lomotil (experimental group) orally 30-60 min prior to scanning. Scans were reviewed independently by two blinded experienced readers and scored for the degree of FDG activity in the lower GI tract relative to liver activity. The administration of Lomotil prior to PET/CT scanning did not reduce physiologic FDG activity in the small bowel and colon. In contrast, increased radiotracer uptake by the lower GI tract was observed in the Lomotil group compared to the control group. Pretreatment with Lomotil prior to PET/CT scanning confers no benefit toward the reduction of physiologic FDG uptake by the small bowel and colon.

Impact of intravenous contrast used in computed tomography on radiation dose to carotid arteries and thyroid in intensity-modulated radiation therapy planning for nasopharyngeal carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Victor Ho Fun, E-mail: vhflee@hku.hk; Ng, Sherry Chor Yi; Kwong, Dora Lai Wan

The aim of this study was to investigate if intravenous contrast injection affected the radiation doses to carotid arteries and thyroid during intensity-modulated radiation therapy (IMRT) planning for nasopharyngeal carcinoma (NPC). Thirty consecutive patients with NPC underwent plain computed tomography (CT) followed by repeated scanning after contrast injection. Carotid arteries (common, external, internal), thyroid, target volumes, and other organs-at-risk (OARs), as well as IMRT planning, were based on contrast-enhanced CT (CE-CT) images. All these structures and the IMRT plans were then copied and transferred to the non–contrast-enhanced CT (NCE-CT) images, and dose calculation without optimization was performed again. The radiationmore » doses to the carotid arteries and the thyroid based on CE-CT and NCE-CT were then compared. Based on CE-CT, no statistical differences, despite minute numeric decreases, were noted in all dosimetric parameters (minimum, maximum, mean, median, D05, and D01) of the target volumes, the OARs, the carotid arteries, and the thyroid compared with NCE-CT. Our results suggested that compared with NCE-CT planning, CE-CT scanning should be performed during IMRT for better target and OAR delineation, without discernible change in radiation doses.« less

Computed tomographic-based quantification of emphysema and correlation to pulmonary function and mechanics.

PubMed

Washko, George R; Criner, Gerald J; Mohsenifar, Zab; Sciurba, Frank C; Sharafkhaneh, Amir; Make, Barry J; Hoffman, Eric A; Reilly, John J

2008-06-01

Computed tomographic based indices of emphysematous lung destruction may highlight differences in disease pathogenesis and further enable the classification of subjects with Chronic Obstructive Pulmonary Disease. While there are multiple techniques that can be utilized for such radiographic analysis, there is very little published information comparing the performance of these methods in a clinical case series. Our objective was to examine several quantitative and semi-quantitative methods for the assessment of the burden of emphysema apparent on computed tomographic scans and compare their ability to predict lung mechanics and function. Automated densitometric analysis was performed on 1094 computed tomographic scans collected upon enrollment into the National Emphysema Treatment Trial. Trained radiologists performed an additional visual grading of emphysema on high resolution CT scans. Full pulmonary function test results were available for correlation, with a subset of subjects having additional measurements of lung static recoil. There was a wide range of emphysematous lung destruction apparent on the CT scans and univariate correlations to measures of lung function were of modest strength. No single method of CT scan analysis clearly outperformed the rest of the group. Quantification of the burden of emphysematous lung destruction apparent on CT scan is a weak predictor of lung function and mechanics in severe COPD with no uniformly superior method found to perform this analysis. The CT based quantification of emphysema may augment pulmonary function testing in the characterization of COPD by providing complementary phenotypic information.

Improved attenuation correction for respiratory gated PET/CT with extended-duration cine CT: a simulation study

NASA Astrophysics Data System (ADS)

Zhang, Ruoqiao; Alessio, Adam M.; Pierce, Larry A.; Byrd, Darrin W.; Lee, Tzu-Cheng; De Man, Bruno; Kinahan, Paul E.

2017-03-01

Due to the wide variability of intra-patient respiratory motion patterns, traditional short-duration cine CT used in respiratory gated PET/CT may be insufficient to match the PET scan data, resulting in suboptimal attenuation correction that eventually compromises the PET quantitative accuracy. Thus, extending the duration of cine CT can be beneficial to address this data mismatch issue. In this work, we propose to use a long-duration cine CT for respiratory gated PET/CT, whose cine acquisition time is ten times longer than a traditional short-duration cine CT. We compare the proposed long-duration cine CT with the traditional short-duration cine CT through numerous phantom simulations with 11 respiratory traces measured during patient PET/CT scans. Experimental results show that, the long-duration cine CT reduces the motion mismatch between PET and CT by 41% and improves the overall reconstruction accuracy by 42% on average, as compared to the traditional short-duration cine CT. The long-duration cine CT also reduces artifacts in PET images caused by misalignment and mismatch between adjacent slices in phase-gated CT images. The improvement in motion matching between PET and CT by extending the cine duration depends on the patient, with potentially greater benefits for patients with irregular breathing patterns or larger diaphragm movements.

TU-F-CAMPUS-I-01: Investigation of the Effective Dose From Bolus Tracking Acquisitions at Different Anatomical Locations in the Chest for CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowik, P; Bujila, R; Merzan, D

2015-06-15

Purpose: Stationary table acquisitions (Bolus tracking) in X-ray Computed Tomography (CT) can Result in dose length products (DLP) comparable to spiral scans. It is today unclear whether or not the effective dose (E) for Bolus Tracking can be approximated using target region specific conversion factors (E/DLP). The purpose of this study was to investigate how E depends on the anatomical location of the Bolus Tracking in relation to Chest CT scans with the same DLP. Methods: Effective doses were approximated for the ICRP 110 adult Reference Male (AM) and adult Reference Female (FM) computational voxel phantoms using software for CTmore » dose approximations (pre-simulated MC data). The effective dose was first approximated for a Chest CT scan using spiral technique and a CTDIvol (32 cm) of 6 mGy. The effective dose from the spiral scan was then compared to E approximated for contiguous Bolus Tracking acquisitions (1 cm separation), with a total collimation of 1 cm, over different locations of the chest of the voxel phantoms. The number of rotations used for the Bolus Tracking acquisitions was adjusted to yield the same DLP (32 cm) as the spiral scan. Results: Depending on the anatomical location of the Bolus Tracking, E ranged by factors of 1.3 to 6.8 for the AM phantom and 1.4 to 3.3 for the AF phantom, compared to the effective dose of the spiral scans. The greatest E for the Bolus Tracking acquisitions was observed for anatomical locations coinciding with breast tissue. This can be expected as breast tissue has a high tissue weighting factor in the calculation of E. Conclusion: For Chest CT scans, the effective dose from Bolus Tracking is highly dependent on the anatomical location where the scan is administered and will not always accurately be represented using target region specific conversion factors.« less

CT biliary cystoscopy of gallbladder polyps

PubMed Central

Lou, Ming-Wu; Hu, Wei-Dong; Fan, Yi; Chen, Jin-Hua; E, Zhan-Sen; Yang, Guang-Fu

2004-01-01

AIM: CT virtual endoscopy has been used in the study of various organs of body including the biliary tract, however, CT virtual endoseopy in diagnosis of gallbladder polyps has not yet been reported. This study was to evaluate the diagnostic value of CT virtual endoscopy in polyps of the gallbladder. METHODS: Thirty-two cases of gallbladder polyps were examined by CT virtual endoscopy, ultrasound, CT scan with oral biliary contrast separately and confirmed by operation and pathology. CT biliary cystoscopic findings were analyzed and compared with those of ultrasound and CT scan with oral biliary contrast, and evaluated in comparison with operative and pathologic findings in all cases. RESULTS: The detection rate of gallbladder polyps was 93.8%(90/96), 96.9%(93/96) and 79.2%(76/96) for CT cystoscopy, ultrasound and CT scan with oral contrast, respectively. CT biliary cystoscopy corresponded well with ultrasound as well as pathology in demonstrating the location, size and configuration of polyps. CT endoscopy was superior to ultrasound in viewing the polyps in a more precise way, 3 dimensionally from any angle in space, and showing the surface in details. CT biliary cystoscopy was also superior to CT scan with oral biliary contrast in terms of observation of the base of polyps for the presence of a pedicle, detection rates as well as image quality. The smallest polyp detected by CT biliary cystoscopy was measured 1.5 mm×2.2 mm×2.5 mm. CONCLUSION: CT biliary cystoscopy is a non-invasive and accurate technique for diagnosis and management of gallbladder polyps. PMID:15069726

Relationship between Hounsfield unit in CT scan and gray scale in CBCT

NASA Astrophysics Data System (ADS)

Kamaruddin, Noorshaida; Rajion, Zainul Ahmad; Yusof, Asilah; Aziz, Mohd Ezane

2016-12-01

Cone-beam computed tomography (CBCT) is an imaging system which has advantages over computed tomography (CT). Recently, CBCT has become widely used for oral and maxillofacial imaging. In CT scan, Hounsfield Unit (HU) is proportional to the degree of x-ray attenuation by the tissue. In CBCT, the degree of x-ray attenuation is shown by gray scale (voxel value). The aim of the present (in vitro) study was to investigate the relationship between gray scale in CBCT and HU in CT scan. In this descriptive study, the anthropomorphic head phantom was scanned with CBCT and CT scanner. Gray scales and HUs were detected on images at the crown of the teeth, trabecular and cortical bone of mandible. The images were analyzed to obtain the gray scale value and HU value. The obtained value then used to investigate the relationship between CBCT gray scales and HUs. For the statistical analysis, t-test, Pearson's correlation and regression analysis were used. The differences between the gray scale of CBCT and HU of CT were statistically not significant, whereas the Pearson's correlation coefficients demonstrated a statistically significant correlation between gray scale of CBCT and HU of CT values. Considering the fact that gray scale in CBCT is important in pre assessment evaluation of bone density before implant treatments, it is recommended because of the lower dose and cost compared to CT scan.

Pelvic CT scan

MedlinePlus

CAT scan - pelvis; Computed axial tomography scan - pelvis; Computed tomography scan - pelvis; CT scan - pelvis ... Risks of CT scans include: Being exposed to radiation Allergic reaction to contrast dye CT scans do expose you to more radiation ...

Shoulder CT scan

MedlinePlus

CAT scan - shoulder; Computed axial tomography scan - shoulder; Computed tomography scan - shoulder; CT scan - shoulder ... Risks of CT scans include: Being exposed to radiation Allergic reaction to contrast dye Birth defect if done during pregnancy CT scans ...

The impact of the introduction of PECARN head CT rules on the utilisation of head CT scans in a private tertiary hospital in Sub-Saharan Africa.

PubMed

Kobe, Isaac O; Qureshi, Mahmoud M; Hassan, Saidi; Oluoch-Olunya, David L

2017-12-01

The decision to order head CT scans to rule out clinically significant traumatic brain injury in mild head injury in children is made on the basis of clinical decision rules of which the Paediatric Emergency Care Applied Research Network (PECARN) CT head rules have been found to be most sensitive. The purpose of this study is to determine the proportion of head CT scans done for children with mild head injury and to determine disposition of patients from casualty after the introduction of PECARN head CT rules compared to the period before. The research question is "will introduction of the PECARN CT head rules reduce the proportion of head CT scans requested for children under 18 years with mild head injury at the AKUHN?" A before and after quasi experimental study with a study population including all children under 18 years presenting to the AKUHN with mild head injury and a Glasgow coma scale of 14 and above on presentation. Sample size was 85. A total of 42 patients files were analysed in the before study while 43 patients were selected for the after study. The median age was 5 years. The proportion of head CT scans reduced from 56% in the before group to 33% in the after group with no missed clinically significant traumatic brain injury. More patients were discharged home after evaluation in the after group (81%) than in the before group (58%). The number of head CT scans ordered reduced without missing any clinically significant traumatic brain injury.

Evaluation of Efficacy of Bone Scan With SPECT/CT in the Management of Low Back Pain: A Study Supported by Differential Diagnostic Local Anesthetic Blocks.

PubMed

Jain, Anuj; Jain, Suruchi; Agarwal, Anil; Gambhir, Sanjay; Shamshery, Chetna; Agarwal, Amita

2015-12-01

Conventional radiologic modalities provide details only about the anatomic aspect of the various structures of the spine. Frequently the structures that show abnormal morphology may not be the cause of low back pain (LBP). Functional imaging in the form of bone scan along with single photon emission computerized tomography (SPECT/CT) may be helpful in identifying structures causing pain, whether morphologically normal or not. The objective of this study is to evaluate the role of bone scan with SPECT/CT in management of patients with LBP. This is randomized double-blinded controlled study performed on 80 patients with LBP aged 20 to 80 years, ASA physical status I to III. Patients were randomized into bone scan and control groups consisting of 40 patients each. On the basis of the clinical features and radiologic findings a clinical diagnosis was made. After making a clinical diagnosis, the patients in bone scan group were subjected to bone scan with SPECT/CT. On the basis of the finding of the bone scan and SPECT/CT, a new working diagnosis was made and intervention was performed according to the new working diagnosis. Diagnostic blocks in the control group were given based on clinical diagnosis. Controlled comparative diagnostic blocks were performed with local anesthetic. The pain score just after the diagnostic block and at the time of discharge (approximately 4 h later) was recorded; the pain relief was recorded in percentage. In both the groups, sacroilitis was the most common diagnosis followed by facet joint arthropathy. The number of patients obtaining pain relief of >50% was significantly higher in the bone scan-positive group as compared with the control group. Three new clinical conditions were identified in the bone scan group. These conditions were multiple myeloma, avascular necrosis of the femoral head, and ankylosing spondylitis. Bone scan with SPECT/CT was found to complement the clinical workup of patients with LBP. Inclusion of bone scan with SPECT/CT in LBP management protocol can help in making a correct diagnosis. At times it might bring out some new information that may be vital for further management of the patients with LBP.

Radiation dose to radiosensitive organs in PET/CT myocardial perfusion examination using versatile optical fibre

NASA Astrophysics Data System (ADS)

Salasiah, M.; Nordin, A. J.; Fathinul Fikri, A. S.; Hishar, H.; Tamchek, N.; Taiman, K.; Ahmad Bazli, A. K.; Abdul-Rashid, H. A.; Mahdiraji, G. A.; Mizanur, R.; Noor, Noramaliza M.

2013-05-01

Cardiac positron emission tomography (PET) provides a precise method in order to diagnose obstructive coronary artery disease (CAD), compared to single photon emission tomography (SPECT). PET is suitable for obese and patients who underwent pharmacologic stress procedures. It has the ability to evaluate multivessel coronary artery disease by recording changes in left ventricular function from rest to peak stress and quantifying myocardial perfusion (in mL/min/g of tissue). However, the radiation dose to the radiosensitive organs has become crucial issues in the Positron Emission Tomography/Computed Tomography(PET/CT) scanning procedure. The objective of this study was to estimate radiation dose to radiosensitive organs of patients who underwent PET/CT myocardial perfusion examination at Centre for Diagnostic Nuclear Imaging, Universiti Putra Malaysia in one month period using versatile optical fibres (Ge-B-doped Flat Fibre) and LiF (TLD-100 chips). All stress and rest paired myocardial perfusion PET/CT scans will be performed with the use of Rubidium-82 (82Rb). The optic fibres were loaded into plastic capsules and attached to patient's eyes, thyroid and breasts prior to the infusion of 82Rb, to accommodate the ten cases for the rest and stress PET scans. The results were compared with established thermoluminescence material, TLD-100 chips. The result shows that radiation dose given by TLD-100 and Germanium-Boron-doped Flat Fiber (Ge-B-doped Flat Fiber) for these five organs were comparable to each other where the p>0.05. For CT scans,thyroid received the highest dose compared to other organs. Meanwhile, for PET scans, breasts received the highest dose.

Radiation from CT scans in paediatric trauma patients: Indications, effective dose, and impact on surgical decisions.

PubMed

Livingston, Michael H; Igric, Ana; Vogt, Kelly; Parry, Neil; Merritt, Neil H

2014-01-01

The purpose of this study was to determine the effective dose of radiation due to computed tomography (CT) scans in paediatric trauma patients at a level 1 Canadian paediatric trauma centre. We also explored the indications and actions taken as a result of these scans. We performed a retrospective review of paediatric trauma patients presenting to our centre from January 1, 2007 to December 31, 2008. All CT scans performed during the initial trauma resuscitation, hospital stay, and 6 months afterwards were included. Effective dose was calculated using the reported dose length product for each scan and conversion factors specific for body region and age of the patient. 157 paediatric trauma patients were identified during the 2-year study period. Mean Injury Severity Score was 22.5 (range 12-75). 133 patients received at least one CT scan. The mean number of scans per patient was 2.6 (range 0-16). Most scans resulted in no further action (56%) or additional imaging (32%). A decision to perform a procedure (2%), surgery (8%), or withdrawal of life support (2%) was less common. The average dose per patient was 13.5mSv, which is 4.5 times the background radiation compared to the general population. CT head was the most commonly performed type of scan and was most likely to be repeated. CT body, defined as a scan of the chest, abdomen, and/or pelvis, was associated with the highest effective dose. CT is a significant source of radiation in paediatric trauma patients. Clinicians should carefully consider the indications for each scan, especially when performing non-resuscitation scans. There is a need for evidence-based treatment algorithms to assist clinicians in selecting appropriate imaging for patients with severe multisystem trauma. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sinus CT scan

MedlinePlus

CAT scan - sinus; Computed axial tomography scan - sinus; Computed tomography scan - sinus; CT scan - sinus ... Risks for a CT scan includes: Being exposed to radiation Allergic reaction to contrast dye CT scans expose you to more radiation than regular ...

Determination of dosimetric quantities in pediatric abdominal computed tomography scans*

PubMed Central

Jornada, Tiago da Silva; da Silva, Teógenes Augusto

2014-01-01

Objective Aiming at contributing to the knowledge on doses in computed tomography (CT), this study has the objective of determining dosimetric quantities associated with pediatric abdominal CT scans, comparing the data with diagnostic reference levels (DRL). Materials and methods The study was developed with a Toshiba Asteion single-slice CT scanner and a GE BrightSpeed multi-slice CT unit in two hospitals. Measurements were performed with a pencil-type ionization chamber and a 16 cm-diameter polymethylmethacrylate trunk phantom. Results No significant difference was observed in the values for weighted air kerma index (CW), but the differences were relevant in values for volumetric air kerma index (CVOL), air kerma-length product (PKL,CT) and effective dose. Conclusion Only the CW values were lower than the DRL, suggesting that dose optimization might not be necessary. However, PKL,CT and effective dose values stressed that there still is room for reducing pediatric radiation doses. The present study emphasizes the importance of determining all dosimetric quantities associated with CT scans. PMID:25741103

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eun-Young Kang; Patz, E.F. Jr.; Mueller, N.L.

Our goal was to assess the CT findings of cytomegalovirus (CMV) pneumonia in transplant patients. The study included 10 transplant patients who had chest CT scan and pathologically proven isolated pulmonary CMV infection. Five patients had bone marrow transplant and five had solid organ transplant. The CT scans were retrospectively reviewed for pattern and distribution of disease and the CT findings compared with the findings on open lung biopsy (n = 9) and autopsy (n = 1). Nine of 10 patients had parenchymal abnormalities apparent at CT and I had normal CT scans. The findings in the nine patients includedmore » small nodules (n = 6), consolidation (n = 4), ground-glass attenuation (n = 4), and irregular lines (n = 1). The nodules had a bilateral and symmetric distribution and involved all lung zones. The consolidation was most marked in the lower lung zones. The CT findings of CMV pneumonia in transplant patients are heterogeneous. The most common patterns include small nodules and areas of consolidation. 13 refs., 4 figs., 1 tab.« less

An Investigation into the Trueness and Precision of Copy Denture Templates Produced by Rapid Prototyping and Conventional Means.

PubMed

Davda, K; Osnes, C; Dillon, S; Wu, J; Hyde, P; Keeling, A

2017-12-01

To assess the trueness and precision of copy denture templates produced using traditional methods and 3D printing. Six copies of a denture were made using: 1. Conventional technique with silicone putty in an impression tray (CT). 2. Conventional technique with no impression tray (CNT). 3. 3D scanning and printing (3D). Scan trueness and precision was investigated by scanning a denture six times and comparing five scans to the sixth. Then the scans of the six CT, CNT and 3D dentures were compared by aligning, in turn, the copies of each denture to the scanned original. Outcome measures were the mean surface-to-surface distance, standard deviation of that distance and the maximum distance. Student's unpaired t-tests with Bonferroni correction were used to analyse the results. The repeated scans of the original denture showed a scan trueness of 0.013mm (SD 0.002) and precision of 0.013mm (SD 0.002). Trueness: CT templates, 0.168mm (0.047), CNT templates 0.195mm (0.034) and 3D 0.103mm (0.021). Precision: CT templates 0.158mm (0.037), CNT 0.233mm (0.073), 3D 0.090mm (0.017). For each outcome measure the 3D templates demonstrated an improvement which was statistically significant (p⟨0.05). 3D printed copy denture templates reproduced the original with greater trueness and precision than conventional techniques. Copyright© 2017 Dennis Barber Ltd.

Intracranial hemorrhage in anticoagulated patients with mild traumatic brain injury: significant differences between direct oral anticoagulants and vitamin K antagonists.

PubMed

Cipriano, Alessandro; Pecori, Alessio; Bionda, Alessandra Eugenia; Bardini, Michele; Frassi, Francesca; Leoli, Francesco; Lami, Valentina; Ghiadoni, Lorenzo; Santini, Massimo

2018-03-08

Prognosis after mild traumatic brain injury (MTBI) on oral anticoagulant therapy (OAT) is uncertain. We evaluated the rate of immediate and delayed traumatic intracranial hemorrhage (ICH) comparing vitamin K antagonists (VKAs) to direct oral anticoagulants (DOACs) and the safety of a clinical management protocol. In this single-center prospective observational study, we enrolled 220 patients on OAT with MTBI. After a first negative CT scan, asymptomatic patients underwent a close neurological observation; if neurologically stable, they were discharged without a second CT scan and followed up for 1 month. Out of the 220 patients, 206 met the inclusion criteria. 23 of them (11.2%) had a positive first CT scan for ICH. Only 1 (0.5%, 95% CI 0.0-1.4%) died because of ICH; no one required neurosurgical intervention. The observed prevalence rate of immediate ICH resulted statistically higher in VKAs-treated patients compared to those treated with DOACs (15.7 vs. 4.7%, RR 3.34, 95% CI 1.18-9.46, P < 0.05). In the 1-month follow-up, 5 out of the 183 patients with a negative CT scan were lost. Out of the remaining 178 patients, only 3 showed a delayed ICH (1.7%, 95% CI 0.0-3.6%), 1 of them died (0.6%, 95% CI 0.5-1.7%) and the others did not require neurosurgical intervention. DOACs resulted safer than VKAs also in the setting of MTBI. In our observation, the rate of delayed hemorrhage was relatively low. Patients presenting with a negative first CT scan and without neurological deterioration could be safely discharged after a short period of in-ward observation with a low rate of complications and without a second CT scan.

Ultrasound detection of pneumothorax compared with chest X-ray and computed tomography scan.

PubMed

Nagarsheth, Khanjan; Kurek, Stanley

2011-04-01

Pneumothorax after trauma can be a life threatening injury and its care requires expeditious and accurate diagnosis and possible intervention. We performed a prospective, single blinded study with convenience sampling at a Level I trauma center comparing thoracic ultrasound with chest X-ray and CT scan in the detection of traumatic pneumothorax. Trauma patients that received a thoracic ultrasound, chest X-ray, and chest CT scan were included in the study. The chest X-rays were read by a radiologist who was blinded to the thoracic ultrasound results. Then both were compared with CT scan results. One hundred and twenty-five patients had a thoracic ultrasound performed in the 24-month period. Forty-six patients were excluded from the study due to lack of either a chest X-ray or chest CT scan. Of the remaining 79 patients there were 22 positive pneumothorax found by CT and of those 18 (82%) were found on ultrasound and 7 (32%) were found on chest X-ray. The sensitivity of thoracic ultrasound was found to be 81.8 per cent and the specificity was found to be 100 per cent. The sensitivity of chest X-ray was found to be 31.8 per cent and again the specificity was found to be 100 per cent. The negative predictive value of thoracic ultrasound for pneumothorax was 0.934 and the negative predictive value for chest X-ray for pneumothorax was found to be 0.792. We advocate the use of chest ultrasound for detection of pneumothorax in trauma patients.

Validation study of an interpolation method for calculating whole lung volumes and masses from reduced numbers of CT-images in ponies.

PubMed

Reich, H; Moens, Y; Braun, C; Kneissl, S; Noreikat, K; Reske, A

2014-12-01

Quantitative computer tomographic analysis (qCTA) is an accurate but time intensive method used to quantify volume, mass and aeration of the lungs. The aim of this study was to validate a time efficient interpolation technique for application of qCTA in ponies. Forty-one thoracic computer tomographic (CT) scans obtained from eight anaesthetised ponies positioned in dorsal recumbency were included. Total lung volume and mass and their distribution into four compartments (non-aerated, poorly aerated, normally aerated and hyperaerated; defined based on the attenuation in Hounsfield Units) were determined for the entire lung from all 5 mm thick CT-images, 59 (55-66) per animal. An interpolation technique validated for use in humans was then applied to calculate qCTA results for lung volumes and masses from only 10, 12, and 14 selected CT-images per scan. The time required for both procedures was recorded. Results were compared statistically using the Bland-Altman approach. The bias ± 2 SD for total lung volume calculated from interpolation of 10, 12, and 14 CT-images was -1.2 ± 5.8%, 0.1 ± 3.5%, and 0.0 ± 2.5%, respectively. The corresponding results for total lung mass were -1.1 ± 5.9%, 0.0 ± 3.5%, and 0.0 ± 3.0%. The average time for analysis of one thoracic CT-scan using the interpolation method was 1.5-2 h compared to 8 h for analysis of all images of one complete thoracic CT-scan. The calculation of pulmonary qCTA data by interpolation from 12 CT-images was applicable for equine lung CT-scans and reduced the time required for analysis by 75%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cadaver-specific CT scans visualized at the dissection table combined with virtual dissection tables improve learning performance in general gross anatomy.

PubMed

Paech, Daniel; Giesel, Frederik L; Unterhinninghofen, Roland; Schlemmer, Heinz-Peter; Kuner, Thomas; Doll, Sara

2017-05-01

The purpose of this study was to quantify the benefit of the incorporation of radiologic anatomy (RA), in terms of student training in RA seminars, cadaver CT scans and life-size virtual dissection tables on the learning success in general anatomy. Three groups of a total of 238 students were compared in a multiple choice general anatomy exam during first-year gross anatomy: (1) a group (year 2015, n 1  = 50) that received training in radiologic image interpretation (RA seminar) and additional access to cadaver CT scans (CT + seminar group); (2) a group (2011, n 2  = 90) that was trained in the RA seminar only (RA seminar group); (3) a group (2011, n 3  = 98) without any radiologic image interpretation training (conventional anatomy group). Furthermore, the students' perception of the new curriculum was assessed qualitatively through a survey. The average test score of the CT + seminar group (21.8 ± 5.0) was significantly higher when compared to both the RA seminar group (18.3 ± 5.0) and the conventional anatomy group (17.1 ± 4.7) (p < 0.001). The incorporation of cadaver CT scans and life-size virtual dissection tables significantly improved the performance of medical students in general gross anatomy. Medical imaging and virtual dissection should therefore be considered to be part of the standard curriculum of gross anatomy. • Students provided with cadaver CT scans achieved 27 % higher scores in anatomy. • Radiological education integrated into gross anatomy is highly appreciated by medical students. • Simultaneous physical and virtual dissection provide unique conditions to study anatomy.

MRI vs. CT for orthodontic applications: comparison of two MRI protocols and three CT (multislice, cone-beam, industrial) technologies.

PubMed

Detterbeck, Andreas; Hofmeister, Michael; Hofmann, Elisabeth; Haddad, Daniel; Weber, Daniel; Hölzing, Astrid; Zabler, Simon; Schmid, Matthias; Hiller, Karl-Heinz; Jakob, Peter; Engel, Jens; Hiller, Jochen; Hirschfelder, Ursula

2016-07-01

To examine the relative usefulness and suitability of magnetic resonance imaging (MRI) in daily clinical practice as compared to various technologies of computed tomography (CT) in addressing questions of orthodontic interest. Three blinded raters evaluated 2D slices and 3D reconstructions created from scans of two pig heads. Five imaging modalities were used, including three CT technologies-multislice (MSCT), cone-beam CT (CBCT), and industrial (µCT)-and two MRI protocols with different scan durations. Defined orthodontic parameters were rated one by one on the 2D slices and the 3D reconstructions, followed by final overall ratings for each modality. A mixed linear model was used for statistical analysis. Based on the 2D slices, the parameter of visualizing tooth-germ topography did not yield any significantly different ratings for MRI versus any of the CT scans. While some ratings for the other parameters did involve significant differences, how these should be interpreted depends greatly on the relevance of each parameter. Based on the 3D reconstructions, the only significant difference between technologies was noted for the parameter of visualizing root-surface morphology. Based on the final overall ratings, the imaging performance of the standard MRI protocol was noninferior to the performance of the three CT technologies. On comparing the imaging performance of MRI and CT scans, it becomes clear that MRI has a huge potential for applications in daily clinical practice. Given its additional benefits of a good contrast ratio and complete absence of ionizing radiation, further studies are needed to explore this clinical potential in greater detail.

Accuracy of DXA scanning of the thoracic spine: cadaveric studies comparing BMC, areal BMD and geometric estimates of volumetric BMD against ash weight and CT measures of bone volume.

PubMed

Sran, Meena M; Khan, Karim M; Keiver, Kathy; Chew, Jason B; McKay, Heather A; Oxland, Thomas R

2005-12-01

Biomechanical studies of the thoracic spine often scan cadaveric segments by dual energy X-ray absorptiometry (DXA) to obtain measures of bone mass. Only one study has reported the accuracy of lateral scans of thoracic vertebral bodies. The accuracy of DXA scans of thoracic spine segments and of anterior-posterior (AP) thoracic scans has not been investigated. We have examined the accuracy of AP and lateral thoracic DXA scans by comparison with ash weight, the gold-standard for measuring bone mineral content (BMC). We have also compared three methods of estimating volumetric bone mineral density (vBMD) with a novel standard-ash weight (g)/bone volume (cm3) as measured by computed tomography (CT). Twelve T5-T8 spine segments were scanned with DXA (AP and lateral) and CT. The T6 vertebrae were excised, the posterior elements removed and then the vertebral bodies were ashed in a muffle furnace. We proposed a new method of estimating vBMD and compared it with two previously published methods. BMC values from lateral DXA scans displayed the strongest correlation with ash weight (r=0.99) and were on average 12.8% higher (p<0.001). As expected, BMC (AP or lateral) was more strongly correlated with ash weight than areal bone mineral density (aBMD; AP: r=0.54, or lateral: r=0.71) or estimated vBMD. Estimates of vBMD with either of the three methods were strongly and similarly correlated with volumetric BMD calculated by dividing ash weight by CT-derived volume. These data suggest that readily available DXA scanning is an appropriate surrogate measure for thoracic spine bone mineral and that the lateral scan might be the scan method of choice.

Whole brain analysis of postmortem density changes of grey and white matter on computed tomography by statistical parametric mapping.

PubMed

Nishiyama, Yuichi; Kanayama, Hidekazu; Mori, Hiroshi; Tada, Keiji; Yamamoto, Yasushi; Katsube, Takashi; Takeshita, Haruo; Kawakami, Kazunori; Kitagaki, Hajime

2017-06-01

This study examined the usefulness of statistical parametric mapping (SPM) for investigating postmortem changes on brain computed tomography (CT). This retrospective study included 128 patients (23 - 100 years old) without cerebral abnormalities who underwent unenhanced brain CT before and after death. The antemortem CT (AMCT) scans and postmortem CT (PMCT) scans were spatially normalized using our original brain CT template, and postmortem changes of CT values (in Hounsfield units; HU) were analysed by the SPM technique. Compared with AMCT scans, 58.6 % and 98.4 % of PMCT scans showed loss of the cerebral sulci and an unclear grey matter (GM)-white matter (WM) interface, respectively. SPM analysis revealed a significant decrease in cortical GM density within 70 min after death on PMCT scans, suggesting cytotoxic brain oedema. Furthermore, there was a significant increase in the density of the WM, lenticular nucleus and thalamus more than 120 min after death. The SPM technique demonstrated typical postmortem changes on brain CT scans, and revealed that the unclear GM-WM interface on early PMCT scans is caused by a rapid decrease in cortical GM density combined with a delayed increase in WM density. SPM may be useful for assessment of whole brain postmortem changes. • The original brain CT template achieved successful normalization of brain morphology. • Postmortem changes in the brain were independent of sex. • Cortical GM density decreased rapidly after death. • WM and deep GM densities increased following cortical GM density change. • SPM could be useful for assessment of whole brain postmortem changes.

Water as neutral oral contrast agent in abdominopelvic CT: comparing effectiveness with Gastrografin in the same patient.

PubMed

Lee, C H; Gu, H Z; Vellayappan, B A; Tan, C H

2016-12-01

Positive oral contrast is no longer deemed necessary for abdominopelvic computed tomography (CT) scans. Studies have shown water to be an equally effective oral contrast agent. However, to our knowledge no study has compared effectiveness between gastrografin and water in the same patient, which will provide a more objective evaluation of the two oral contrast agents. We aim to make a head-to-head comparison of water as neutral oral contrast (OC) against gastrografin as positive OC for abdominopelvic CT scans in the same patient. A retrospective review of 206 abdominopelvic CT scans of 103 patients was performed. The scans were reviewed in consensus by two blinded radiologists. The ability to visualise each abdominopelvic organ, contrastassociated artefacts and small bowel wall delineation, was qualitatively scored on a 5-point scale. Each patient had two sets of scores, one with water and another with gastrografin as OC. Paired scores from the two OCs were evaluated by Wilcoxon signed rank test to determine any significant difference in performance between the two OCs for visualisation of abdominopelvic anatomy on CT. There was significantly better delineation of duodenal wall (p<0.001) and overall visualisation of the duodenum (p=0.011) using water as OC compared to gastrografin. No statistically significant differences were demonstrated between water and gastrografin for visualisation of the rest of the abdominopelvic organs, walldelineation of the rest small bowel and contrast-associated artefacts. Water can be used in place of gastrografin as oral contrast in abdominopelvic CT without compromising visualization of abdominopelvic organs.

Organ doses for reference pediatric and adolescent patients undergoing computed tomography estimated by Monte Carlo simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.

Purpose: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model. Methods: The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs/tissues normalized to the product of 100 mAs and CTDI{sub vol} (mGy/100 mAs mGy) was established by coupling the CT scanner model with age-dependentmore » reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI{sub vol}- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP). Results: Organ and effective doses were calculated and normalized to 100 mAs and CTDI{sub vol} for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and/or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose differences up to several-fold when organs were partially included in the scan coverage. Second, selected organ doses from our calculations agreed to within 20% of values derived from empirical formulae based upon measured patient abdominal circumference. Third, the existing DLP-to-effective dose conversion coefficients tended to be smaller than values given in the present study for all examinations except head scans. Conclusions: A comprehensive organ/effective dose database was established to readily calculate doses for given patients undergoing different CT examinations. The comparisons of our results with the existing studies highlight that use of hybrid phantoms with realistic anatomy is important to improve the accuracy of CT organ dosimetry. The comprehensive pediatric dose data developed here are the first organ-specific pediatric CT scan database based on the realistic pediatric hybrid phantoms which are compliant with the reference data from the International Commission on Radiological Protection (ICRP). The organ dose database is being coupled with an adult organ dose database recently published as part of the development of a user-friendly computer program enabling rapid estimates of organ and effective dose doses for patients of any age, gender, examination types, and CT scanner model.« less

Application of fluence field modulation to proton computed tomography for proton therapy imaging.

PubMed

Dedes, G; De Angelis, L; Rit, S; Hansen, D; Belka, C; Bashkirov, V; Johnson, R P; Coutrakon, G; Schubert, K E; Schulte, R W; Parodi, K; Landry, G

2017-07-12

This simulation study presents the application of fluence field modulated computed tomography, initially developed for x-ray CT, to proton computed tomography (pCT). By using pencil beam (PB) scanning, fluence modulated pCT (FMpCT) may achieve variable image quality in a pCT image and imaging dose reduction. Three virtual phantoms, a uniform cylinder and two patients, were studied using Monte Carlo simulations of an ideal list-mode pCT scanner. Regions of interest (ROI) were selected for high image quality and only PBs intercepting them preserved full fluence (FF). Image quality was investigated in terms of accuracy (mean) and noise (standard deviation) of the reconstructed proton relative stopping power compared to reference values. Dose calculation accuracy on FMpCT images was evaluated in terms of dose volume histograms (DVH), range difference (RD) for beam-eye-view (BEV) dose profiles and gamma evaluation. Pseudo FMpCT scans were created from broad beam experimental data acquired with a list-mode pCT prototype. FMpCT noise in ROIs was equivalent to FF images and accuracy better than  -1.3%(-0.7%) by using 1% of FF for the cylinder (patients). Integral imaging dose reduction of 37% and 56% was achieved for the two patients for that level of modulation. Corresponding DVHs from proton dose calculation on FMpCT images agreed to those from reference images and 96% of BEV profiles had RD below 2 mm, compared to only 1% for uniform 1% of FF. Gamma pass rates (2%, 2 mm) were 98% for FMpCT while for uniform 1% of FF they were as low as 59%. Applying FMpCT to preliminary experimental data showed that low noise levels and accuracy could be preserved in a ROI, down to 30% modulation. We have shown, using both virtual and experimental pCT scans, that FMpCT is potentially feasible and may allow a means of imaging dose reduction for a pCT scanner operating in PB scanning mode. This may be of particular importance to proton therapy given the low integral dose found outside the target.

Lung texture in serial thoracic CT scans: Assessment of change introduced by image registration1

PubMed Central

Cunliffe, Alexandra R.; Al-Hallaq, Hania A.; Labby, Zacariah E.; Pelizzari, Charles A.; Straus, Christopher; Sensakovic, William F.; Ludwig, Michelle; Armato, Samuel G.

2012-01-01

Purpose: The aim of this study was to quantify the effect of four image registration methods on lung texture features extracted from serial computed tomography (CT) scans obtained from healthy human subjects. Methods: Two chest CT scans acquired at different time points were collected retrospectively for each of 27 patients. Following automated lung segmentation, each follow-up CT scan was registered to the baseline scan using four algorithms: (1) rigid, (2) affine, (3) B-splines deformable, and (4) demons deformable. The registration accuracy for each scan pair was evaluated by measuring the Euclidean distance between 150 identified landmarks. On average, 1432 spatially matched 32 × 32-pixel region-of-interest (ROI) pairs were automatically extracted from each scan pair. First-order, fractal, Fourier, Laws’ filter, and gray-level co-occurrence matrix texture features were calculated in each ROI, for a total of 140 features. Agreement between baseline and follow-up scan ROI feature values was assessed by Bland–Altman analysis for each feature; the range spanned by the 95% limits of agreement of feature value differences was calculated and normalized by the average feature value to obtain the normalized range of agreement (nRoA). Features with small nRoA were considered “registration-stable.” The normalized bias for each feature was calculated from the feature value differences between baseline and follow-up scans averaged across all ROIs in every patient. Because patients had “normal” chest CT scans, minimal change in texture feature values between scan pairs was anticipated, with the expectation of small bias and narrow limits of agreement. Results: Registration with demons reduced the Euclidean distance between landmarks such that only 9% of landmarks were separated by ≥1 mm, compared with rigid (98%), affine (95%), and B-splines (90%). Ninety-nine of the 140 (71%) features analyzed yielded nRoA > 50% for all registration methods, indicating that the majority of feature values were perturbed following registration. Nineteen of the features (14%) had nRoA < 15% following demons registration, indicating relative feature value stability. Student's t-tests showed that the nRoA of these 19 features was significantly larger when rigid, affine, or B-splines registration methods were used compared with demons registration. Demons registration yielded greater normalized bias in feature value change than B-splines registration, though this difference was not significant (p = 0.15). Conclusions: Demons registration provided higher spatial accuracy between matched anatomic landmarks in serial CT scans than rigid, affine, or B-splines algorithms. Texture feature changes calculated in healthy lung tissue from serial CT scans were smaller following demons registration compared with all other algorithms. Though registration altered the values of the majority of texture features, 19 features remained relatively stable after demons registration, indicating their potential for detecting pathologic change in serial CT scans. Combined use of accurate deformable registration using demons and texture analysis may allow for quantitative evaluation of local changes in lung tissue due to disease progression or treatment response. PMID:22894392

Evaluation of organ doses in CT examinations with an infant anthropomorphic phantom.

PubMed

Fujii, K; Akahane, K; Miyazaki, O; Horiuchi, T; Shimada, A; Nagmatsu, H; Yamauchi, M; Yamauchi-Kawaura, C; Kawasaki, T

2011-09-01

The aim of this study is to evaluate organ doses in infant CT examinations with multi-detector row CT scanners. Radiation doses were measured with radiophotoluminescence glass dosemeters set in various organ positions within a 1-y-old child anthropomorphic phantom and organ doses were evaluated from the measurement values. Doses for tissues or organs within the scan range were 28-36 mGy in an infant head CT, 3-11 mGy in a chest CT, 5-11 mGy in an abdominal-pelvic CT and 2-14 mGy in a cardiac CT. The doses varied by the differences in the types of CT scanners and scan parameters used at each medical facility. Compared with those for children of various ages, the doses in an infant CT protocol were found to be similar to or slightly smaller than those in a paediatric CT for 5- or 6-y-old children.

SU-E-I-09: The Impact of X-Ray Scattering On Image Noise for Dedicated Breast CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, K; Gazi, P; Boone, J

2015-06-15

Purpose: To quantify the impact of detected x-ray scatter on image noise in flat panel based dedicated breast CT systems and to determine the optimal scanning geometry given practical trade-offs between radiation dose and scatter reduction. Methods: Four different uniform polyethylene cylinders (104, 131, 156, and 184 mm in diameter) were scanned as the phantoms on a dedicated breast CT scanner developed in our laboratory. Both stationary projection imaging and rotational cone-beam CT imaging was performed. For each acquisition type, three different x-ray beam collimations were used (12, 24, and 109 mm measured at isocenter). The aim was to quantifymore » image noise properties (pixel variance, SNR, and image NPS) under different levels of x-ray scatter, in order to optimize the scanning geometry. For both projection images and reconstructed CT images, individual pixel variance and NPS were determined and compared. Noise measurement from the CT images were also performed with different detector binning modes and reconstruction matrix sizes. Noise propagation was also tracked throughout the intermediate steps of cone-beam CT reconstruction, including the inverse-logarithmic process, Fourier-filtering before backprojection. Results: Image noise was lower in the presence of higher scatter levels. For the 184 mm polyethylene phantom, the image noise (measured in pixel variance) was ∼30% lower with full cone-beam acquisition compared to a narrow (12 mm) fan-beam acquisition. This trend is consistent across all phantom sizes and throughout all steps of CT image reconstruction. Conclusion: From purely a noise perspective, the cone-beam geometry (i.e. the full cone-angle acquisition) produces lower image noise compared to the lower-scatter fan-beam acquisition for breast CT. While these results are relevant in homogeneous phantoms, the full impact of scatter on noise in bCT should involve contrast-to-noise-ratio measurements in heterogeneous phantoms if the goal is to optimize the scanning geometry for dedicated breast CT. This work was supported by a grant from the National Institute for Biomedical Imaging and Bioengineering (R01 EB002138)« less

Growth characterisation of intra-thoracic organs of children on CT scans.

PubMed

Coulongeat, François; Jarrar, Mohamed-Salah; Thollon, Lionel; Serre, Thierry

2013-01-01

This paper analyses the geometry of intra-thoracic organs from computed tomography (CT) scans performed on 20 children aged from 4 months to 16 years. The aim is to find the most reliable measurements to characterise the growth of heart and lungs from CT data. Standard measurements available on chest radiographies are compared with original measurements only available on CT scans. These measurements should characterise the growth of organs as well as the changes in their position relative to the thorax. Measurements were considered as functions of age. Quadratic regression models were fitted to the data. Goodness of fit of the models was then evaluated. Positions of organs relative to the thorax have a high variability compared with their changes with age. The length and volume of the heart and lungs as well as the diameter of the thorax fit well to the models of growth. It could be interesting to study these measurements with a larger sample size in order to define growth standards.

Estimation of skull table thickness with clinical CT and validation with microCT.

PubMed

Lillie, Elizabeth M; Urban, Jillian E; Weaver, Ashley A; Powers, Alexander K; Stitzel, Joel D

2015-01-01

Brain injuries resulting from motor vehicle crashes (MVC) are extremely common yet the details of the mechanism of injury remain to be well characterized. Skull deformation is believed to be a contributing factor to some types of traumatic brain injury (TBI). Understanding biomechanical contributors to skull deformation would provide further insight into the mechanism of head injury resulting from blunt trauma. In particular, skull thickness is thought be a very important factor governing deformation of the skull and its propensity for fracture. Current computed tomography (CT) technology is limited in its ability to accurately measure cortical thickness using standard techniques. A method to evaluate cortical thickness using cortical density measured from CT data has been developed previously. This effort validates this technique for measurement of skull table thickness in clinical head CT scans using two postmortem human specimens. Bone samples were harvested from the skulls of two cadavers and scanned with microCT to evaluate the accuracy of the estimated cortical thickness measured from clinical CT. Clinical scans were collected at 0.488 and 0.625 mm in plane resolution with 0.625 mm thickness. The overall cortical thickness error was determined to be 0.078 ± 0.58 mm for cortical samples thinner than 4 mm. It was determined that 91.3% of these differences fell within the scanner resolution. Color maps of clinical CT thickness estimations are comparable to color maps of microCT thickness measurements, indicating good quantitative agreement. These data confirm that the cortical density algorithm successfully estimates skull table thickness from clinical CT scans. The application of this technique to clinical CT scans enables evaluation of cortical thickness in population-based studies. © 2014 Anatomical Society.

Prevalence of Extracochlear Electrodes: Computerized Tomography Scans, Cochlear Implant Maps, and Operative Reports.

PubMed

Holder, Jourdan T; Kessler, David M; Noble, Jack H; Gifford, René H; Labadie, Robert F

2018-06-01

To quantify and compare the number of cochlear implant (CI) electrodes found to be extracochlear on postoperative computerized tomography (CT) scans, the number of basal electrodes deactivated during standard CI mapping (without knowledge of the postoperative CT scan), and the extent of electrode insertion noted by the surgeon. Retrospective. Academic Medical Center. Two hundred sixty-two patients underwent standard cochlear implantation and postoperative temporal bone CT scanning. Scans were analyzed to determine the number of extracochlear electrodes. Standard CI programming had been completed without knowledge of the extracochlear electrodes identified on the CT. These standard CI maps were reviewed to record the number of deactivated basal electrodes. Lastly, each operative report was reviewed to record the extent of reported electrode insertion. 13.4% (n = 35) of CIs were found to have at least one electrode outside of the cochlea on the CT scan. Review of CI mapping indicated that audiologists had deactivated extracochlear electrodes in 60% (21) of these cases. Review of operative reports revealed that surgeons correctly indicated the number of extracochlear electrodes in 6% (2) of these cases. Extracochlear electrodes were correctly identified audiologically in 60% of cases and in surgical reports in 6% of cases; however, it is possible that at least a portion of these cases involved postoperative electrode migration. Given these findings, postoperative CT scans can provide information regarding basal electrode location, which could help improve programming accuracy, associated frequency allocation, and audibility with appropriate deactivation of extracochlear electrodes.

SU-F-J-123: CT-Based Determination of DIBH Variability and Its Dosimetric Impact On Post-Mastectomy Plus Regional Nodal Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malin, M; Kang, H; Tatebe, K

Purpose: Breast cancer radiotherapy delivered using voluntary deep inspiration breath-hold (DIBH) requires reproducible breath holds, particularly when matching supraclavicular fields to tangential fields. We studied the impact of variation in DIBHs on CTV and OAR dose metrics by comparing the dose distribution computed on two DIBH CT scans taken at the time of simulation. Methods: Ten patients receiving 50Gy in 25 fractions to the left chestwall and regional lymph nodes were studied. Two simulation CT scans were taken during separate DIBHs along with a free-breathing (FB) scan. The treatment was planned using one DIBH CT. The dose was recomputed onmore » the other two scans using adaptive planning (Pinnacle 9.10) in which the scans are registered using a cross-correlation algorithm. The chestwall, lymph nodes and OARs were contoured on the scans following the RTOG consensus guidelines. The overall translational and rotational variation between the DIBH scans was used to estimate positional variation between breath-holds. Dose metrics between plans were compared using paired t-tests (p < 0.05) and means and standard deviations were reported. Results: The registration parameters were sub-millimeter and sub-degree. Although DIBH significantly reduced mean heart dose by 2.4Gy compared to FB (p < 0.01), no significant changes in dose were observed for targets or OARs between the two DIBH scans. Nodal coverage as assessed by V90% was 90%±8% and 89%±8% for supraclavicular and 99%±2% and 97%±22% for IM nodes. Though a significant decrease (10.5%±12.4%) in lung volume in the second DIBH CT was observed, the lung V20Gy was unchanged (14±2% and 14±3%) between the two DIBH scans. Conclusion: While the lung volume often varied between DIBHs, the CTV and OAR dose metrics were largely unchanged. This indicates that manual DIBH has the potential to provide consistent dose delivery to the chestwall and regional nodes targets when using matched fields.« less

Adaptive statistical iterative reconstruction use for radiation dose reduction in pediatric lower-extremity CT: impact on diagnostic image quality.

PubMed

Shah, Amisha; Rees, Mitchell; Kar, Erica; Bolton, Kimberly; Lee, Vincent; Panigrahy, Ashok

2018-06-01

For the past several years, increased levels of imaging radiation and cumulative radiation to children has been a significant concern. Although several measures have been taken to reduce radiation dose during computed tomography (CT) scan, the newer dose reduction software adaptive statistical iterative reconstruction (ASIR) has been an effective technique in reducing radiation dose. To our knowledge, no studies are published that assess the effect of ASIR on extremity CT scans in children. To compare radiation dose, image noise, and subjective image quality in pediatric lower extremity CT scans acquired with and without ASIR. The study group consisted of 53 patients imaged on a CT scanner equipped with ASIR software. The control group consisted of 37 patients whose CT images were acquired without ASIR. Image noise, Computed Tomography Dose Index (CTDI) and dose length product (DLP) were measured. Two pediatric radiologists rated the studies in subjective categories: image sharpness, noise, diagnostic acceptability, and artifacts. The CTDI (p value = 0.0184) and DLP (p value <0.0002) were significantly decreased with the use of ASIR compared with non-ASIR studies. However, the subjective ratings for sharpness (p < 0.0001) and diagnostic acceptability of the ASIR images (p < 0.0128) were decreased compared with standard, non-ASIR CT studies. Adaptive statistical iterative reconstruction reduces radiation dose for lower extremity CTs in children, but at the expense of diagnostic imaging quality. Further studies are warranted to determine the specific utility of ASIR for pediatric musculoskeletal CT imaging.

MRI simulation: end-to-end testing for prostate radiation therapy using geometric pelvic MRI phantoms

NASA Astrophysics Data System (ADS)

Sun, Jidi; Dowling, Jason; Pichler, Peter; Menk, Fred; Rivest-Henault, David; Lambert, Jonathan; Parker, Joel; Arm, Jameen; Best, Leah; Martin, Jarad; Denham, James W.; Greer, Peter B.

2015-04-01

To clinically implement MRI simulation or MRI-alone treatment planning requires comprehensive end-to-end testing to ensure an accurate process. The purpose of this study was to design and build a geometric phantom simulating a human male pelvis that is suitable for both CT and MRI scanning and use it to test geometric and dosimetric aspects of MRI simulation including treatment planning and digitally reconstructed radiograph (DRR) generation. A liquid filled pelvic shaped phantom with simulated pelvic organs was scanned in a 3T MRI simulator with dedicated radiotherapy couch-top, laser bridge and pelvic coil mounts. A second phantom with the same external shape but with an internal distortion grid was used to quantify the distortion of the MR image. Both phantoms were also CT scanned as the gold-standard for both geometry and dosimetry. Deformable image registration was used to quantify the MR distortion. Dose comparison was made using a seven-field IMRT plan developed on the CT scan with the fluences copied to the MR image and recalculated using bulk electron densities. Without correction the maximum distortion of the MR compared with the CT scan was 7.5 mm across the pelvis, while this was reduced to 2.6 and 1.7 mm by the vendor’s 2D and 3D correction algorithms, respectively. Within the locations of the internal organs of interest, the distortion was <1.5 and <1 mm with 2D and 3D correction algorithms, respectively. The dose at the prostate isocentre calculated on CT and MRI images differed by 0.01% (1.1 cGy). Positioning shifts were within 1 mm when setup was performed using MRI generated DRRs compared to setup using CT DRRs. The MRI pelvic phantom allows end-to-end testing of the MRI simulation workflow with comparison to the gold-standard CT based process. MRI simulation was found to be geometrically accurate with organ dimensions, dose distributions and DRR based setup within acceptable limits compared to CT.

Multi-Mounted X-Ray Computed Tomography.

PubMed

Fu, Jian; Liu, Zhenzhong; Wang, Jingzheng

2016-01-01

Most existing X-ray computed tomography (CT) techniques work in single-mounted mode and need to scan the inspected objects one by one. It is time-consuming and not acceptable for the inspection in a large scale. In this paper, we report a multi-mounted CT method and its first engineering implementation. It consists of a multi-mounted scanning geometry and the corresponding algebraic iterative reconstruction algorithm. This approach permits the CT rotation scanning of multiple objects simultaneously without the increase of penetration thickness and the signal crosstalk. Compared with the conventional single-mounted methods, it has the potential to improve the imaging efficiency and suppress the artifacts from the beam hardening and the scatter. This work comprises a numerical study of the method and its experimental verification using a dataset measured with a developed multi-mounted X-ray CT prototype system. We believe that this technique is of particular interest for pushing the engineering applications of X-ray CT.

A new functional method to choose the target lobe for lung volume reduction in emphysema - comparison with the conventional densitometric method.

PubMed

Hetzel, Juergen; Boeckeler, Michael; Horger, Marius; Ehab, Ahmed; Kloth, Christopher; Wagner, Robert; Freitag, Lutz; Slebos, Dirk-Jan; Lewis, Richard Alexander; Haentschel, Maik

2017-01-01

Lung volume reduction (LVR) improves breathing mechanics by reducing hyperinflation. Lobar selection usually focuses on choosing the most destroyed emphysematous lobes as seen on an inspiratory CT scan. However, it has never been shown to what extent these densitometric CT parameters predict the least deflation of an individual lobe during expiration. The addition of expiratory CT analysis allows measurement of the extent of lobar air trapping and could therefore provide additional functional information for choice of potential treatment targets. To determine lobar vital capacity/lobar total capacity (LVC/LTC) as a functional parameter for lobar air trapping using on an inspiratory and expiratory CT scan. To compare lobar selection by LVC/LTC with the established morphological CT density parameters. 36 patients referred for endoscopic LVR were studied. LVC/LTC, defined as delta volume over maximum volume of a lobe, was calculated using inspiratory and expiratory CT scans. The CT morphological parameters of mean lung density (MLD), low attenuation volume (LAV), and 15th percentile of Hounsfield units (15%P) were determined on an inspiratory CT scan for each lobe. We compared and correlated LVC/LTC with MLD, LAV, and 15%P. There was a weak correlation between the functional parameter LVC/LTC and all inspiratory densitometric parameters. Target lobe selection using lowest lobar deflation (lowest LVC/LTC) correlated with target lobe selection based on lowest MLD in 18 patients (50.0%), with the highest LAV in 13 patients (36.1%), and with the lowest 15%P in 12 patients (33.3%). CT-based measurement of deflation (LVC/LTC) as a functional parameter correlates weakly with all densitometric CT parameters on a lobar level. Therefore, morphological criteria based on inspiratory CT densitometry partially reflect the deflation of particular lung lobes, and may be of limited value as a sole predictor for target lobe selection in LVR.

Individually optimized contrast-enhanced 4D-CT for radiotherapy simulation in pancreatic ductal adenocarcinoma

PubMed Central

Xue, Ming; Lane, Barton F.; Kang, Min Kyu; Patel, Kruti; Regine, William F.; Klahr, Paul; Wang, Jiahui; Chen, Shifeng; D’Souza, Warren; Lu, Wei

2016-01-01

Purpose: To develop an individually optimized contrast-enhanced (CE) 4D-computed tomography (CT) for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). Methods: Ten PDA patients were enrolled. Each underwent three CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT using test injection. Three physicians contoured the tumor and pancreatic tissues. Image quality scores, tumor volume, motion, tumor-to-pancreas contrast, and contrast-to-noise ratio (CNR) were compared in the three CTs. Interobserver variations were also evaluated in contouring the tumor using simultaneous truth and performance level estimation. Results: Average image quality scores for CE 3D-CT and CE 4D-CT were comparable (4.0 and 3.8, respectively; P = 0.082), and both were significantly better than that for 4D-CT (2.6, P < 0.001). Tumor-to-pancreas contrast results were comparable in CE 3D-CT and CE 4D-CT (15.5 and 16.7 Hounsfield units (HU), respectively; P = 0.21), and the latter was significantly higher than in 4D-CT (9.2 HU, P = 0.001). Image noise in CE 3D-CT (12.5 HU) was significantly lower than in CE 4D-CT (22.1 HU, P = 0.013) and 4D-CT (19.4 HU, P = 0.009). CNRs were comparable in CE 3D-CT and CE 4D-CT (1.4 and 0.8, respectively; P = 0.42), and both were significantly better in 4D-CT (0.6, P = 0.008 and 0.014). Mean tumor volumes were significantly smaller in CE 3D-CT (29.8 cm3, P = 0.03) and CE 4D-CT (22.8 cm3, P = 0.01) than in 4D-CT (42.0 cm3). Mean tumor motion was comparable in 4D-CT and CE 4D-CT (7.2 and 6.2 mm, P = 0.17). Interobserver variations were comparable in CE 3D-CT and CE 4D-CT (Jaccard index 66.0% and 61.9%, respectively) and were worse for 4D-CT (55.6%) than CE 3D-CT. Conclusions: CE 4D-CT demonstrated characteristics comparable to CE 3D-CT, with high potential for simultaneously delineating the tumor and quantifying tumor motion with a single scan. PMID:27782710

Automated volumetry of temporal horn of lateral ventricle for detection of Alzheimer's disease in CT scan

NASA Astrophysics Data System (ADS)

Takahashi, Noriyuki; Kinoshita, Toshibumi; Ohmura, Tomomi; Matsuyama, Eri; Toyoshima, Hideto

2018-02-01

The rapid increase in the incidence of Alzheimer's disease (AD) has become a critical issue in low and middle income countries. In general, MR imaging has become sufficiently suitable in clinical situations, while CT scan might be uncommonly used in the diagnosis of AD due to its low contrast between brain tissues. However, in those countries, CT scan, which is less costly and readily available, will be desired to become useful for the diagnosis of AD. For CT scan, the enlargement of the temporal horn of the lateral ventricle (THLV) is one of few findings for the diagnosis of AD. In this paper, we present an automated volumetry of THLV with segmentation based on Bayes' rule on CT images. In our method, first, all CT data sets are normalized into an atlas by using linear affine transformation and non-linear wrapping techniques. Next, a probability map of THLV is constructed in the normalized data. Then, THLV regions are extracted based on Bayes' rule. Finally, the volume of the THLV is evaluated. This scheme was applied to CT scans from 20 AD patients and 20 controls to evaluate the performance of the method for detecting AD. The estimated THLV volume was markedly increased in the AD group compared with the controls (P < .0001), and the area under the receiver operating characteristic curve (AUC) was 0.921. Therefore, this computerized method may have the potential to accurately detect AD on CT images.

CT radiation profile width measurement using CR imaging plate raw data

PubMed Central

Yang, Chang‐Ying Joseph

2015-01-01

This technical note demonstrates computed tomography (CT) radiation profile measurement using computed radiography (CR) imaging plate raw data showing it is possible to perform the CT collimation width measurement using a single scan without saturating the imaging plate. Previously described methods require careful adjustments to the CR reader settings in order to avoid signal clipping in the CR processed image. CT radiation profile measurements were taken as part of routine quality control on 14 CT scanners from four vendors. CR cassettes were placed on the CT scanner bed, raised to isocenter, and leveled. Axial scans were taken at all available collimations, advancing the cassette for each scan. The CR plates were processed and raw CR data were analyzed using MATLAB scripts to measure collimation widths. The raw data approach was compared with previously established methodology. The quality control analysis scripts are released as open source using creative commons licensing. A log‐linear relationship was found between raw pixel value and air kerma, and raw data collimation width measurements were in agreement with CR‐processed, bit‐reduced data, using previously described methodology. The raw data approach, with intrinsically wider dynamic range, allows improved measurement flexibility and precision. As a result, we demonstrate a methodology for CT collimation width measurements using a single CT scan and without the need for CR scanning parameter adjustments which is more convenient for routine quality control work. PACS numbers: 87.57.Q‐, 87.59.bd, 87.57.uq PMID:26699559

Correlation between differential renal function estimation using CT-based functional renal parenchymal volume and (99m)Tc - DTPA renal scan.

PubMed

Sarma, Debanga; Barua, Sasanka K; Rajeev, T P; Baruah, Saumar J

2012-10-01

Nuclear renal scan is currently the gold standard imaging study to determine differential renal function. We propose helical CT as single modality for both the anatomical and functional evaluation of kidney with impaired function. In the present study renal parenchymal volume is measured and percent total renal volume is used as a surrogate marker for differential renal function. The objective of this study is to correlate between differential renal function estimation using CT-based renal parenchymal volume measurement with differential renal function estimation using (99m)TC - DTPA renal scan. Twenty-one patients with unilateral obstructive uropathy were enrolled in this prospective comparative study. They were subjected to (99m)Tc - DTPA renal scan and 64 slice helical CT scan which estimates the renal volume depending on the reconstruction of arterial phase images followed by volume rendering and percent renal volume was calculated. Percent renal volume was correlated with percent renal function, as determined by nuclear renal scan using Pearson coefficient. RESULTS AND OBSERVATION: A strong correlation is observed between percent renal volume and percent renal function in obstructed units (r = 0.828, P < 0.001) as well as in nonobstructed units (r = 0.827, P < 0.001). There is a strong correlation between percent renal volume determined by CT scan and percent renal function determined by (99m)TC - DTPA renal scan both in obstructed and in normal units. CT-based percent renal volume can be used as a single radiological tests for both functional and anatomical assessment of impaired renal units.

18F-FDG PET/CT in Detecting Metastatic Infection in Children.

PubMed

Kouijzer, Ilse J E; Blokhuis, Gijsbert J; Draaisma, Jos M T; Oyen, Wim J G; de Geus-Oei, Lioe-Fee; Bleeker-Rovers, Chantal P

2016-04-01

Metastatic infection is a severe complication of bacteremia with high morbidity and mortality. The aim of this study was to investigate the diagnostic value of 18F-FDG PET combined with CT (FDG PET/CT) in children suspected of having metastatic infection. The results of FDG PET/CT scans performed in children because of suspected metastatic infection from September 2003 to June 2013 were analyzed retrospectively. The results were compared with the final clinical diagnosis. FDG PET/CT was performed in 13 children with suspected metastatic infection. Of the total number of FDG PET/CT scans, 38% were clinically helpful. Positive predictive value of FDG PET/CT was 71%, and negative predictive value was 100%. FDG PET/CT appears to be a valuable diagnostic technique in children with suspected metastatic infection. Prospective studies of FDG PET/CT as part of a structured diagnostic protocol are needed to assess the exact additional diagnostic value.

Estimating the effective radiation dose imparted to patients by intraoperative cone-beam computed tomography in thoracolumbar spinal surgery.

PubMed

Lange, Jeffrey; Karellas, Andrew; Street, John; Eck, Jason C; Lapinsky, Anthony; Connolly, Patrick J; Dipaola, Christian P

2013-03-01

Observational. To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios. Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses. Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors. Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3. We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases with patient size, and the radiation dose received by larger patients as a result of more than 3 O-arm scans in standard mode may exceed the dose received during standard CT of the abdomen. Understanding radiation imparted to patients by cone-beam CT is important for assessing risks and benefits of this technology, especially when spinal surgical procedures require multiple intraoperative scans.

CT Scan-Guided Abrams' Needle Pleural Biopsy versus Ultrasound-Assisted Cutting Needle Pleural Biopsy for Diagnosis in Patients with Pleural Effusion: A Randomized, Controlled Trial.

PubMed

Metintas, Muzaffer; Yildirim, Huseyin; Kaya, Tamer; Ak, Guntulu; Dundar, Emine; Ozkan, Ragip; Metintas, Selma

2016-01-01

Image-guided pleural biopsies, both using ultrasound (US) or computed tomography (CT), are important in the diagnosis of pleural disease. However, no consensus exists regarding which biopsy needles are appropriate for specific procedures. In this randomized, prospective study, we aimed to compare CT scan-guided pleural biopsy using an Abrams' needle (CT-ANPB) with US-assisted pleural biopsy using a cutting needle (US-CNPB) with respect to both diagnostic yield and safety. Between February 2009 and April 2013, 150 patients with exudative pleural effusion who could not be diagnosed by cytological analysis were included in the study. The patients were randomized into either the US-CNPB group or the CT-ANPB group. The two groups were compared in terms of diagnostic sensitivity and complications. Of the 150 patients enrolled in this study, 45 were diagnosed with malignant mesothelioma, 46 were diagnosed with metastatic pleural disease, 18 were diagnosed with pleural tuberculosis, 34 were diagnosed with benign pleural disease, and 7 were lost to follow-up. In the US-CNPB group, the diagnostic sensitivity was 66.7%, compared with 82.4% in the CT-ANPB group; the difference between the two groups was statistically significant (p = 0.029). The sensitivity of CT-ANPB increased to 93.7% for patients with a pleural thickness ≥1 cm. The complication rates were low and acceptable. The first diagnostic intervention that should be preferred in patients with pleural effusion and associated pleural thickening on a CT scan is CT-ANPB. US-CNPB should be used primarily in cases for which only pleural thickening but no pleural effusion is noted. © 2016 S. Karger AG, Basel.

Pre-operative prediction of cervical nodal metastasis in papillary thyroid cancer by 99mTc-MIBI SPECT/CT; a pilot study.

PubMed

Tangjaturonrasme, Napadon; Vasavid, Pataramon; Sombuntham, Premsuda; Keelawat, Somboon

2013-06-01

Papillary thyroid cancer has a high prevalence of cervical nodal metastasis. There is no "gold standard" imaging for pre-operative diagnosis. The aim of the present study was to assess the accuracy of pre-operative 99mTc-MBI SPECT/CT in diagnosis of cervical nodal metastasis in patients with papillary thyroid cancer Fifteen patients were performed 99Tc-MlBI SPECT/CT pre-operatively. Either positive pathological report of neck dissection or positive post-treatment I-131 whole body scan with SPECT/CT of neck was concluded for definite neck metastasis. The PPV, NPV, and accuracy of 99mTc-MIBI SPECT/CT were analyzed. The PPV NPV and accuracy were 80%, 88.89%, and 85.71%, respectively. 99mTc-MIBI SPECT/CT could localize the abnormal lymph nodes groups correctly in most cases when compared with pathological results. However the authors found one false positive case with caseating granulomatous lymphadenitis and one false negative case with positive post-treatment 1-131 whole body scan with SPECT/CT of neck on cervical nodes zone II and IV CONCLUSION: 99mTc-MIBI SPECT/CTseem promising for pre-operative staging of cervical nodal involvement in patients with papillary thyroid cancer without the need of using iodinated contrast that may complicate subsequence 1-131 treatment. However, false positive result in granulomatous inflammatory nodes should be aware of especially in endemic areas. 99mTc-MIBI SPECT/CT scan shows a good result when compared with previous study of CT or MRI imaging. The comparative study between different imaging modality and the extension of neck dissection according to MIBI result seems interesting.

Diagnostic value of FDG-PET/(CT) in children with fever of unknown origin and unexplained fever during immune suppression.

PubMed

Blokhuis, Gijsbert J; Bleeker-Rovers, Chantal P; Diender, Marije G; Oyen, Wim J G; Draaisma, Jos M Th; de Geus-Oei, Lioe-Fee

2014-10-01

Fever of unknown origin (FUO) and unexplained fever during immune suppression in children are challenging medical problems. The aim of this study is to investigate the diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and FDG-PET combined with computed tomography (FDG-PET/CT) in children with FUO and in children with unexplained fever during immune suppression. All FDG-PET/(CT) scans performed in the Radboud university medical center for the evaluation of FUO or unexplained fever during immune suppression in the last 10 years were reviewed. Results were compared with the final clinical diagnosis. FDG-PET/(CT) scans were performed in 31 children with FUO. A final diagnosis was established in 16 cases (52 %). Of the total number of scans, 32 % were clinically helpful. The sensitivity and specificity of FDG-PET/CT in these patients was 80 % and 78 %, respectively. FDG-PET/(CT) scans were performed in 12 children with unexplained fever during immune suppression. A final diagnosis was established in nine patients (75 %). Of the total number of these scans, 58 % were clinically helpful. The sensitivity and specificity of FDG-PET/CT in children with unexplained fever during immune suppression was 78 % and 67 %, respectively. FDG-PET/CT appears a valuable imaging technique in the evaluation of children with FUO and in the diagnostic process of children with unexplained fever during immune suppression. Prospective studies of FDG-PET/CT as part of a structured diagnostic protocol are warranted to assess the additional diagnostic value.

Gray Matter-White Matter De-Differentiation on Brain Computed Tomography Predicts Brain Death Occurrence.

PubMed

Vigneron, C; Labeye, V; Cour, M; Hannoun, S; Grember, A; Rampon, F; Cotton, F

2016-01-01

Previous studies have shown that a loss of distinction between gray matter (GM) and white matter (WM) on unenhanced CT scans was predictive of poor outcome after cardiac arrest. The aim of this study was to identify a marker/predictor of imminent brain death. In this retrospective study, 15 brain-dead patients after anoxia and cardiac arrest were included. Patients were paired (1:1) with normal control subjects. Only patients' unenhanced CT scans performed before brain death and during the 24 hours after initial signs were analyzed. WM and GM densities were measured in predefined regions of interest (basal ganglia level, centrum semi-ovale level, high convexity level, brainstem level). At each level, GM and WM density and GM/WM ratio for brain-dead patients and normal control subjects were compared using the Wilcoxon signed-rank test. At each level, a lower GM/WM ratio and decreased GM and WM densities were observed in brain-dead patients' CT scans when compared with normal control subject CT scans. A cut-off value of 1.21 at the basal ganglia level was identified, below which brain death systematically occurred. GM/WM dedifferentiation on unenhanced CT scan is measurable before the occurrence of brain death, highlighting its importance in brain death prediction. The mechanism of GM/WM differentiation loss could be explained by the lack of oxygen caused by ischemia initially affecting the mitochondrial system. Copyright © 2016 Elsevier Inc. All rights reserved.

Preoperative 4D CT Localization of Nonlocalizing Parathyroid Adenomas by Ultrasound and SPECT-CT.

PubMed

Hinson, Andrew M; Lee, David R; Hobbs, Bradley A; Fitzgerald, Ryan T; Bodenner, Donald L; Stack, Brendan C

2015-11-01

To evaluate 4-dimensional (4D) computed tomography (CT) for the localization of parathyroid adenomas previously considered nonlocalizing on ultrasound and single-photon emission CT with CT scanning (SPECT-CT). To measure radiation exposure associated with 4D-CT and compared it with SPECT-CT. Case series with chart review. University tertiary hospital. Nineteen adults with primary hyperparathyroidism who underwent preoperative 4D CT from November 2013 through July 2014 after nonlocalizing preoperative ultrasound and technetium-99m SPECT-CT scans. Sensitivity, specificity, predictive values, and accuracy of 4D CT were evaluated. Nineteen patients (16 women and 3 men) were included with a mean age of 66 years (range, 39-80 years). Mean preoperative parathyroid hormone level was 108.5 pg/mL (range, 59.3-220.9 pg/mL), and mean weight of the excised gland was 350 mg (range, 83-797 mg). 4D CT sensitivity and specificity for localization to the patient's correct side of the neck were 84.2% and 81.8%, respectively; accuracy was 82.9%. The sensitivity for localizing adenomas to the correct quadrant was 76.5% and 91.5%, respectively; accuracy was 88.2%. 4D CT radiation exposure was significantly less than the radiation associated with SPECT-CT (13.8 vs 18.4 mSv, P = 0.04). 4D CT localizes parathyroid adenomas with relatively high sensitivity and specificity and allows for the localization of some adenomas not observed on other sestamibi-based scans. 4D CT was also associated with less radiation exposure when compared with SPECT-CT based on our study protocol. 4D CT may be considered as first- or second-line imaging for localizing parathyroid adenomas in the setting of primary hyperparathyroidism. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

68Ga-PSMA PET/CT in patients with recurrent prostate cancer after radical treatment: prospective results in 314 patients.

PubMed

Caroli, Paola; Sandler, Israel; Matteucci, Federica; De Giorgi, Ugo; Uccelli, Licia; Celli, Monica; Foca, Flavia; Barone, Domenico; Romeo, Antonino; Sarnelli, Anna; Paganelli, Giovanni

2018-06-19

We studied the usefulness of 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT for detecting relapse in a prospective series of patients with biochemical recurrence (BCR) of prostate cancer (PCa) after radical treatment. Patients with BCR of PCa after radical surgery and/or radiotherapy with or without androgen-deprivation therapy were included in the study. 68 Ga-PSMA PET/CT scans performed from the top of the head to the mid-thigh 60 min after intravenous injection of 150 ± 50 MBq of 68 Ga-PSMA were interpreted by two nuclear medicine physicians. The results were correlated with prostate-specific antigen (PSA) levels at the time of the scan (PSApet), PSA doubling time, Gleason score, tumour stage, postsurgery tumour residue, time from primary therapy to BCR, and patient age. When available, 68 Ga-PSMA PET/CT scans were compared with negative 18 F-choline PET/CT scans routinely performed up to 1 month previously. From November 2015 to October 2017, 314 PCa patients with BCR were evaluated. Their median age was 70 years (range 44-92 years) and their median PSApet was 0.83 ng/ml (range 0.003-80.0 ng/ml). 68 Ga-PSMA PET/CT was positive (one or more suspected PCa lesions detected) in 197 patients (62.7%). Lesions limited to the pelvis, i.e. the prostate/prostate bed and/or pelvic lymph nodes (LNs), were detected in 117 patients (59.4%). At least one distant lesion (LNs, bone, other organs, separately or combined with local lesions) was detected in 80 patients (40.6%). PSApet was higher in PET-positive than in PET-negative patients (P < 0.0001). Of 88 patients negative on choline PET/CT scans, 59 (67%) were positive on 68 Ga-PSMA PET/CT. We confirmed the value of 68 Ga-PSMA PET/CT in restaging PCa patients with BCR, highlighting its superior performance and safety compared with choline PET/CT. Higher PSApet was associated with a higher relapse detection rate.

Edge guided image reconstruction in linear scan CT by weighted alternating direction TV minimization.

PubMed

Cai, Ailong; Wang, Linyuan; Zhang, Hanming; Yan, Bin; Li, Lei; Xi, Xiaoqi; Li, Jianxin

2014-01-01

Linear scan computed tomography (CT) is a promising imaging configuration with high scanning efficiency while the data set is under-sampled and angularly limited for which high quality image reconstruction is challenging. In this work, an edge guided total variation minimization reconstruction (EGTVM) algorithm is developed in dealing with this problem. The proposed method is modeled on the combination of total variation (TV) regularization and iterative edge detection strategy. In the proposed method, the edge weights of intermediate reconstructions are incorporated into the TV objective function. The optimization is efficiently solved by applying alternating direction method of multipliers. A prudential and conservative edge detection strategy proposed in this paper can obtain the true edges while restricting the errors within an acceptable degree. Based on the comparison on both simulation studies and real CT data set reconstructions, EGTVM provides comparable or even better quality compared to the non-edge guided reconstruction and adaptive steepest descent-projection onto convex sets method. With the utilization of weighted alternating direction TV minimization and edge detection, EGTVM achieves fast and robust convergence and reconstructs high quality image when applied in linear scan CT with under-sampled data set.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paliwal, B; Asprey, W; Yan, Y

Purpose: In order to take advantage of the high resolution soft tissue imaging available in MR images, we investigated 3D images obtained with the low field 0.35 T MR in ViewRay to serve as an alternative to CT scans for radiotherapy treatment planning. In these images, normal and target structure delineation can be visualized. Assessment is based upon comparison with the CT images and the ability to produce comparable contours. Methods: Routine radiation oncology CT scans were acquired on five patients. Contours of brain, brainstem, esophagus, heart, lungs, spinal cord, and the external body were drawn. The same five patientsmore » were then scanned on the ViewRay TrueFISP-based imaging pulse sequence. The same organs were selected on the MR images and compared to those from the CT scan. Physical volume and the Dice Similarity Coefficient (DSC) were used to assess the contours from the two systems. Image quality stability was quantitatively ensured throughout the study following the recommendations of the ACR MR accreditation procedure. Results: The highest DSC of 0.985, 0.863, and 0.843 were observed for brain, lungs, and heart respectively. On the other hand, the brainstem, spinal cord, and esophagus had the lowest DSC. Volume agreement was most satisfied for the heart (within 5%) and the brain (within 2%). Contour volume for the brainstem and lung (a widely dynamic organ) varied the most (27% and 19%). Conclusion: The DSC and volume measurements suggest that the results obtained from ViewRay images are quantitatively consistent and comparable to those obtained from CT scans for the brain, heart, and lungs. MR images from ViewRay are well-suited for treatment planning and for adaptive MRI-guided radiotherapy. The physical data from 0.35 T MR imaging is consistent with our geometrical understanding of normal structures.« less

Cross-sectional anatomy, computed tomography and magnetic resonance imaging of the head of common dolphin (Delphinus delphis) and striped dolphin (Stenella coeruleoalba).

PubMed

Alonso-Farré, J M; Gonzalo-Orden, M; Barreiro-Vázquez, J D; Barreiro-Lois, A; André, M; Morell, M; Llarena-Reino, M; Monreal-Pawlowsky, T; Degollada, E

2015-02-01

Computed tomography (CT) and low-field magnetic resonance imaging (MRI) were used to scan seven by-caught dolphin cadavers, belonging to two species: four common dolphins (Delphinus delphis) and three striped dolphins (Stenella coeruleoalba). CT and MRI were obtained with the animals in ventral recumbency. After the imaging procedures, six dolphins were frozen at -20°C and sliced in the same position they were examined. Not only CT and MRI scans, but also cross sections of the heads were obtained in three body planes: transverse (slices of 1 cm thickness) in three dolphins, sagittal (5 cm thickness) in two dolphins and dorsal (5 cm thickness) in two dolphins. Relevant anatomical structures were identified and labelled on each cross section, obtaining a comprehensive bi-dimensional topographical anatomy guide of the main features of the common and the striped dolphin head. Furthermore, the anatomical cross sections were compared with their corresponding CT and MRI images, allowing an imaging identification of most of the anatomical features. CT scans produced an excellent definition of the bony and air-filled structures, while MRI allowed us to successfully identify most of the soft tissue structures in the dolphin's head. This paper provides a detailed anatomical description of the head structures of common and striped dolphins and compares anatomical cross sections with CT and MRI scans, becoming a reference guide for the interpretation of imaging studies. © 2014 Blackwell Verlag GmbH.

The accuracy of ultrashort echo time MRI sequences for medical additive manufacturing.

PubMed

van Eijnatten, Maureen; Rijkhorst, Erik-Jan; Hofman, Mark; Forouzanfar, Tymour; Wolff, Jan

2016-01-01

Additively manufactured bone models, implants and drill guides are becoming increasingly popular amongst maxillofacial surgeons and dentists. To date, such constructs are commonly manufactured using CT technology that induces ionizing radiation. Recently, ultrashort echo time (UTE) MRI sequences have been developed that allow radiation-free imaging of facial bones. The aim of the present study was to assess the feasibility of UTE MRI sequences for medical additive manufacturing (AM). Three morphologically different dry human mandibles were scanned using a CT and MRI scanner. Additionally, optical scans of all three mandibles were made to acquire a "gold standard". All CT and MRI scans were converted into Standard Tessellation Language (STL) models and geometrically compared with the gold standard. To quantify the accuracy of the AM process, the CT, MRI and gold-standard STL models of one of the mandibles were additively manufactured, optically scanned and compared with the original gold-standard STL model. Geometric differences between all three CT-derived STL models and the gold standard were <1.0 mm. All three MRI-derived STL models generally presented deviations <1.5 mm in the symphyseal and mandibular area. The AM process introduced minor deviations of <0.5 mm. This study demonstrates that MRI using UTE sequences is a feasible alternative to CT in generating STL models of the mandible and would therefore be suitable for surgical planning and AM. Further in vivo studies are necessary to assess the usability of UTE MRI sequences in clinical settings.

Simulation of computed tomography dose based on voxel phantom

NASA Astrophysics Data System (ADS)

Liu, Chunyu; Lv, Xiangbo; Li, Zhaojun

2017-01-01

Computed Tomography (CT) is one of the preferred and the most valuable imaging tool used in diagnostic radiology, which provides a high-quality cross-sectional image of the body. It still causes higher doses of radiation to patients comparing to the other radiological procedures. The Monte-Carlo method is appropriate for estimation of the radiation dose during the CT examinations. The simulation of the Computed Tomography Dose Index (CTDI) phantom was developed in this paper. Under a similar conditions used in physical measurements, dose profiles were calculated and compared against the measured values that were reported. The results demonstrate a good agreement between the calculated and the measured doses. From different CT exam simulations using the voxel phantom, the highest absorbed dose was recorded for the lung, the brain, the bone surface. A comparison between the different scan type shows that the effective dose for a chest scan is the highest one, whereas the effective dose values during abdomen and pelvis scan are very close, respectively. The lowest effective dose resulted from the head scan. Although, the dose in CT is related to various parameters, such as the tube current, exposure time, beam energy, slice thickness and patient size, this study demonstrates that the MC simulation is a useful tool to accurately estimate the dose delivered to any specific organs for patients undergoing the CT exams and can be also a valuable technique for the design and the optimization of the CT x-ray source.

Community-Acquired Pneumonia Visualized on CT Scans but Not Chest Radiographs: Pathogens, Severity, and Clinical Outcomes.

PubMed

Upchurch, Cameron P; Grijalva, Carlos G; Wunderink, Richard G; Williams, Derek J; Waterer, Grant W; Anderson, Evan J; Zhu, Yuwei; Hart, Eric M; Carroll, Frank; Bramley, Anna M; Jain, Seema; Edwards, Kathryn M; Self, Wesley H

2018-03-01

The clinical significance of pneumonia visualized on CT scan in the setting of a normal chest radiograph is uncertain. In a multicenter prospective surveillance study of adults hospitalized with community-acquired pneumonia (CAP), we compared the presenting clinical features, pathogens present, and outcomes of patients with pneumonia visualized on a CT scan but not on a concurrent chest radiograph (CT-only pneumonia) and those with pneumonia visualized on a chest radiograph. All patients underwent chest radiography; the decision to obtain CT imaging was determined by the treating clinicians. Chest radiographs and CT images were interpreted by study-dedicated thoracic radiologists blinded to the clinical data. The study population included 2,251 adults with CAP; 2,185 patients (97%) had pneumonia visualized on chest radiography, whereas 66 patients (3%) had pneumonia visualized on CT scan but not on concurrent chest radiography. Overall, these patients with CT-only pneumonia had a clinical profile similar to those with pneumonia visualized on chest radiography, including comorbidities, vital signs, hospital length of stay, prevalence of viral (30% vs 26%) and bacterial (12% vs 14%) pathogens, ICU admission (23% vs 21%), use of mechanical ventilation (6% vs 5%), septic shock (5% vs 4%), and inhospital mortality (0 vs 2%). Adults hospitalized with CAP who had radiological evidence of pneumonia on CT scan but not on concurrent chest radiograph had pathogens, disease severity, and outcomes similar to patients who had signs of pneumonia on chest radiography. These findings support using the same management principles for patients with CT-only pneumonia and those with pneumonia seen on chest radiography. Copyright © 2017 American College of Chest Physicians. All rights reserved.

Validation of calculation algorithms for organ doses in CT by measurements on a 5 year old paediatric phantom

NASA Astrophysics Data System (ADS)

Dabin, Jérémie; Mencarelli, Alessandra; McMillan, Dayton; Romanyukha, Anna; Struelens, Lara; Lee, Choonsik

2016-06-01

Many organ dose calculation tools for computed tomography (CT) scans rely on the assumptions: (1) organ doses estimated for one CT scanner can be converted into organ doses for another CT scanner using the ratio of the Computed Tomography Dose Index (CTDI) between two CT scanners; and (2) helical scans can be approximated as the summation of axial slices covering the same scan range. The current study aims to validate experimentally these two assumptions. We performed organ dose measurements in a 5 year-old physical anthropomorphic phantom for five different CT scanners from four manufacturers. Absorbed doses to 22 organs were measured using thermoluminescent dosimeters for head-to-torso scans. We then compared the measured organ doses with the values calculated from the National Cancer Institute dosimetry system for CT (NCICT) computer program, developed at the National Cancer Institute. Whereas the measured organ doses showed significant variability (coefficient of variation (CoV) up to 53% at 80 kV) across different scanner models, the CoV of organ doses normalised to CTDIvol substantially decreased (12% CoV on average at 80 kV). For most organs, the difference between measured and simulated organ doses was within  ±20% except for the bone marrow, breasts and ovaries. The discrepancies were further explained by additional Monte Carlo calculations of organ doses using a voxel phantom developed from CT images of the physical phantom. The results demonstrate that organ doses calculated for one CT scanner can be used to assess organ doses from other CT scanners with 20% uncertainty (k  =  1), for the scan settings considered in the study.

Differentiation of dental restorative materials combining energy-dispersive X-ray fluorescence spectroscopy and post-mortem CT.

PubMed

Merriam, Tim; Kaufmann, Rolf; Ebert, Lars; Figi, Renato; Erni, Rolf; Pauer, Robin; Sieberth, Till

2018-06-01

Today, post-mortem computed tomography (CT) is routinely used for forensic identification. Mobile energy-dispersive X-ray fluorescence (EDXRF) spectroscopy of a dentition is a method of identification that has the potential to be easier and cheaper than CT, although it cannot be used with every dentition. In challenging cases, combining both techniques could facilitate the process of identification and prove to be advantageous over chemical analyses. Nine dental restorative material brands were analyzed using EDXRF spectroscopy. Their differentiability was assessed by comparing each material's x-ray fluorescence spectrum and then comparing the spectra to previous research investigating differentiability in CT. To verify EDXRF's precision and accuracy, select dental specimens underwent comparative electron beam excited x-ray spectroscopy (EDS) scans, while the impact of the restorative surface area was studied by scanning a row of dental specimens with varying restorative surface areas (n = 10). EDXRF was able to differentiate all 36 possible pairs of dental filling materials; however, dual-energy CT was only able to differentiate 33 out of 36. The EDS scans showed correlating x-ray fluorescence peaks on the x-ray spectra compared to our EDXRF. In addition, the surface area showed no influence on the differentiability of the dental filling materials. EDXRF has the potential to facilitate corpse identification by differentiating and comparing restorative materials, providing more information compared to post-mortem CT alone. Despite not being able to explicitly identify a brand without a control sample or database, its fast and mobile use could accelerate daily routines or mass victim identification processes. To achieve this goal, further development of EDXRF scanners for this application and further studies evaluating the method within a specific routine need to be performed.

SU-F-I-33: Estimating Radiation Dose in Abdominal Fat Quantitative CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, X; Yang, K; Liu, B

Purpose: To compare size-specific dose estimate (SSDE) in abdominal fat quantitative CT with another dose estimate D{sub size,L} that also takes into account scan length. Methods: This study complied with the requirements of the Health Insurance Portability and Accountability Act. At our institution, abdominal fat CT is performed with scan length = 1 cm and CTDI{sub vol} = 4.66 mGy (referenced to body CTDI phantom). A previously developed CT simulation program was used to simulate single rotation axial scans of 6–55 cm diameter water cylinders, and dose integral of the longitudinal dose profile over the central 1 cm length wasmore » used to predict the dose at the center of one-cm scan range. SSDE and D{sub size,L} were assessed for 182 consecutive abdominal fat CT examinations with mean water-equivalent diameter (WED) of 27.8 cm ± 6.0 (range, 17.9 - 42.2 cm). Patient age ranged from 18 to 75 years, and weight ranged from 39 to 163 kg. Results: Mean SSDE was 6.37 mGy ± 1.33 (range, 3.67–8.95 mGy); mean D{sub size,L} was 2.99 mGy ± 0.85 (range, 1.48 - 4.88 mGy); and mean D{sub size,L}/SSDE ratio was 0.46 ± 0.04 (range, 0.40 - 0.55). Conclusion: The conversion factors for size-specific dose estimate in AAPM Report No. 204 were generated using 15 - 30 cm scan lengths. One needs to be cautious in applying SSDE to small length CT scans. For abdominal fat CT, SSDE was 80–150% higher than the dose of 1 cm scan length.« less

Pulmonary tularaemia: all that looks like cancer is not necessarily cancer - case report of four consecutive cases.

PubMed

Fachinger, Patrick; Tini, Gabrielo Mauro; Grobholz, Rainer; Gambazzi, Franco; Fankhauser, Hans; Irani, Sarosh

2015-03-26

Pulmonary tularaemia is a very rare disease with only a small number of cases described in the literature. So far, to our knowledge, there exists no case report of pulmonary tularaemia where PET-CT scans and follow up CT scans are available. We present four consecutive cases of pulmonary tularaemia. All patients suffered from non-specific symptoms. All patients were referred to our institution with strong suspicions of malignancy, particularly lung cancer. Diagnosis of tularaemia was made by typical findings in the aspirate of EBUS guided fine needle aspiration (necrosis, epithelioid cell aggregation) and surgical biopsy respectively, and a positive serology. In three of the four cases, the diagnosis was confirmed by positive PCR results of the tissue. PET-CT scans obtained in all four cases were indistinguishable from lesions typically seen in patients suffering from lung cancer. One of the four patients suffered from recurrence of the disease after antibiotic treatment; also this patient finally recovered after initiation of a second antibiotic regimen. One case became asymptomatic spontaneously, but this patient still received an antibiotic treatment. In one case, a follow up CT scan was unchanged compared to the initial PET-CT scan; in all other cases, the lesions disappeared almost completely. Symptoms of patients suffering from pulmonary tularaemia are non-specific and can be of prolonged character. PET-CT scans in these cases are indistinguishable from lung cancer. The diagnosis can be established when typical findings in EBUS guided fine needle aspirates or surgical biopsies are found in combination with a positive serology. In most cases the lesions disappear in follow up CT scans after clinically successful treatment.

Abdominal CT scan

MedlinePlus

Computed tomography scan - abdomen; CT scan - abdomen; CT abdomen and pelvis ... An abdominal CT scan makes detailed pictures of the structures inside your belly very quickly. This test may be used to look ...

Evaluation of a semiautomated lung mass calculation technique for internal dosimetry applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Busse, Nathan; Erwin, William; Pan, Tinsu

2013-12-15

Purpose: The authors sought to evaluate a simple, semiautomated lung mass estimation method using computed tomography (CT) scans obtained using a variety of acquisition techniques and reconstruction parameters for mass correction of medical internal radiation dose-based internal radionuclide radiation absorbed dose estimates.Methods: CT scans of 27 patients with lung cancer undergoing stereotactic body radiation therapy treatment planning with PET/CT were analyzed retrospectively. For each patient, free-breathing (FB) and respiratory-gated 4DCT scans were acquired. The 4DCT scans were sorted into ten respiratory phases, representing one complete respiratory cycle. An average CT reconstruction was derived from the ten-phase reconstructions. Mid expiration breath-holdmore » CT scans were acquired in the same session for many patients. Deep inspiration breath-hold diagnostic CT scans of many of the patients were obtained from different scanning sessions at similar time points to evaluate the effect of contrast administration and maximum inspiration breath-hold. Lung mass estimates were obtained using all CT scan types, and intercomparisons made to assess lung mass variation according to scan type. Lung mass estimates using the FB CT scans from PET/CT examinations of another group of ten male and ten female patients who were 21–30 years old and did not have lung disease were calculated and compared with reference lung mass values. To evaluate the effect of varying CT acquisition and reconstruction parameters on lung mass estimation, an anthropomorphic chest phantom was scanned and reconstructed with different CT parameters. CT images of the lungs were segmented using the OsiriX MD software program with a seed point of about −850 HU and an interval of 1000. Lung volume, and mean lung, tissue, and air HUs were recorded for each scan. Lung mass was calculated by assuming each voxel was a linear combination of only air and tissue. The specific gravity of lung volume was calculated using the formula (lung HU − air HU)/(tissue HU − air HU), and mass = specific gravity × total volume × 1.04 g/cm{sup 3}.Results: The range of calculated lung masses was 0.51–1.29 kg. The average male and female lung masses during FB CT were 0.80 and 0.71 kg, respectively. The calculated lung mass varied across the respiratory cycle but changed to a lesser degree than did lung volume measurements (7.3% versus 15.4%). Lung masses calculated using deep inspiration breath-hold and average CT were significantly larger (p < 0.05) than were some masses calculated using respiratory-phase and FB CT. Increased voxel size and smooth reconstruction kernels led to high lung mass estimates owing to partial volume effects.Conclusions: Organ mass correction is an important component of patient-specific internal radionuclide dosimetry. Lung mass calculation necessitates scan-based density correction to account for volume changes owing to respiration. The range of lung masses in the authors’ patient population represents lung doses for the same absorbed energy differing from 25% below to 64% above the dose found using reference phantom organ masses. With proper management of acquisition parameters and selection of FB or midexpiration breath hold scans, lung mass estimates with about 10% population precision may be achieved.« less

NCICT: a computational solution to estimate organ doses for pediatric and adult patients undergoing CT scans.

PubMed

Lee, Choonsik; Kim, Kwang Pyo; Bolch, Wesley E; Moroz, Brian E; Folio, Les

2015-12-01

We developed computational methods and tools to assess organ doses for pediatric and adult patients undergoing computed tomography (CT) examinations. We used the International Commission on Radiological Protection (ICRP) reference pediatric and adult phantoms combined with the Monte Carlo simulation of a reference CT scanner to establish comprehensive organ dose coefficients (DC), organ absorbed dose per unit volumetric CT Dose Index (CTDIvol) (mGy/mGy). We also developed methods to estimate organ doses with tube current modulation techniques and size specific dose estimates. A graphical user interface was designed to obtain user input of patient- and scan-specific parameters, and to calculate and display organ doses. A batch calculation routine was also integrated into the program to automatically calculate organ doses for a large number of patients. We entitled the computer program, National Cancer Institute dosimetry system for CT(NCICT). We compared our dose coefficients with those from CT-Expo, and evaluated the performance of our program using CT patient data. Our pediatric DCs show good agreements of organ dose estimation with those from CT-Expo except for thyroid. Our results support that the adult phantom in CT-Expo seems to represent a pediatric individual between 10 and 15 years rather than an adult. The comparison of CTDIvol values between NCICT and dose pages from 10 selected CT scans shows good agreements less than 12% except for two cases (up to 20%). The organ dose comparison between mean and modulated mAs shows that mean mAs-based calculation significantly overestimates dose (up to 2.4-fold) to the organs in close proximity to lungs in chest and chest-abdomen-pelvis scans. Our program provides more realistic anatomy based on the ICRP reference phantoms, higher age resolution, the most up-to-date bone marrow dosimetry, and several convenient features compared to previous tools. The NCICT will be available for research purpose in the near future.

Cervical spine CT scan

MedlinePlus

... cervical spine; Computed tomography scan of cervical spine; CT scan of cervical spine; Neck CT scan ... table that slides into the center of the CT scanner. Once you are inside the scanner, the ...

Selected PET radiomic features remain the same.

PubMed

Tsujikawa, Tetsuya; Tsuyoshi, Hideaki; Kanno, Masafumi; Yamada, Shizuka; Kobayashi, Masato; Narita, Norihiko; Kimura, Hirohiko; Fujieda, Shigeharu; Yoshida, Yoshio; Okazawa, Hidehiko

2018-04-17

We investigated whether PET radiomic features are affected by differences in the scanner, scan protocol, and lesion location using 18 F-FDG PET/CT and PET/MR scans. SUV, TMR, skewness, kurtosis, entropy, and homogeneity strongly correlated between PET/CT and PET/MR images. SUVs were significantly higher on PET/MR 0-2 min and PET/MR 0-10 min than on PET/CT in gynecological cancer ( p = 0.008 and 0.008, respectively), whereas no significant difference was observed between PET/CT, PET/MR 0-2 min , and PET/MR 0-10 min images in oral cavity/oropharyngeal cancer. TMRs on PET/CT, PET/MR 0-2 min , and PET/MR 0-10 min increased in this order in gynecological cancer and oral cavity/oropharyngeal cancer. In contrast to conventional and histogram indices, 4 textural features (entropy, homogeneity, SRE, and LRE) were not significantly different between PET/CT, PET/MR 0-2 min , and PET/MR 0-10 min images. 18 F-FDG PET radiomic features strongly correlated between PET/CT and PET/MR images. Dixon-based attenuation correction on PET/MR images underestimated tumor tracer uptake more significantly in oral cavity/oropharyngeal cancer than in gynecological cancer. 18 F-FDG PET textural features were affected less by differences in the scanner and scan protocol than conventional and histogram features, possibly due to the resampling process using a medium bin width. Eight patients with gynecological cancer and 7 with oral cavity/oropharyngeal cancer underwent a whole-body 18 F-FDG PET/CT scan and regional PET/MR scan in one day. PET/MR scans were performed for 10 minutes in the list mode, and PET/CT and 0-2 min and 0-10 min PET/MR images were reconstructed. The standardized uptake value (SUV), tumor-to-muscle SUV ratio (TMR), skewness, kurtosis, entropy, homogeneity, short-run emphasis (SRE), and long-run emphasis (LRE) were compared between PET/CT, PET/MR 0-2 min , and PET/MR 0-10 min images.

Coronary artery calcium: a multi-institutional, multimanufacturer international standard for quantification at cardiac CT.

PubMed

McCollough, Cynthia H; Ulzheimer, Stefan; Halliburton, Sandra S; Shanneik, Kaiss; White, Richard D; Kalender, Willi A

2007-05-01

To develop a consensus standard for quantification of coronary artery calcium (CAC). A standard for CAC quantification was developed by a multi-institutional, multimanufacturer international consortium of cardiac radiologists, medical physicists, and industry representatives. This report specifically describes the standardization of scan acquisition and reconstruction parameters, the use of patient size-specific tube current values to achieve a prescribed image noise, and the use of the calcium mass score to eliminate scanner- and patient size-based variations. An anthropomorphic phantom containing calibration inserts and additional phantom rings were used to simulate small, medium-size, and large patients. The three phantoms were scanned by using the recommended protocols for various computed tomography (CT) systems to determine the calibration factors that relate measured CT numbers to calcium hydroxyapatite density and to determine the tube current values that yield comparable noise values. Calculation of the calcium mass score was standardized, and the variance in Agatston, volume, and mass scores was compared among CT systems. Use of the recommended scanning parameters resulted in similar noise for small, medium-size, and large phantoms with all multi-detector row CT scanners. Volume scores had greater interscanner variance than did Agatston and calcium mass scores. Use of a fixed calcium hydroxyapatite density threshold (100 mg/cm(3)), as compared with use of a fixed CT number threshold (130 HU), reduced interscanner variability in Agatston and calcium mass scores. With use of a density segmentation threshold, the calcium mass score had the smallest variance as a function of patient size. Standardized quantification of CAC yielded comparable image noise, spatial resolution, and mass scores among different patient sizes and different CT systems and facilitated reduced radiation dose for small and medium-size patients.

Leg CT scan

MedlinePlus

CAT scan - leg; Computed axial tomography scan - leg; Computed tomography scan - leg; CT scan - leg ... CT scan makes detailed pictures of the body very quickly. The test may help look for: An abscess ...

Arm CT scan

MedlinePlus

CAT scan - arm; Computed axial tomography scan - arm; Computed tomography scan - arm; CT scan - arm ... Healing problems or scar tissue following surgery A CT scan may also be used to guide a surgeon ...

Emergency medicine summary code for reporting CT scan results: implementation and survey results.

PubMed

Lam, Joanne; Coughlin, Ryan; Buhl, Luce; Herbst, Meghan; Herbst, Timothy; Martillotti, Jared; Coughlin, Bret

2018-06-01

The purpose of the study was to assess the emergency department (ED) providers' interest and satisfaction with ED CT result reporting before and after the implementation of a standardized summary code for all CT scan reporting. A summary code was provided at the end of all CTs ordered through the ED from August to October of 2016. A retrospective review was completed on all studies performed during this period. A pre- and post-survey was given to both ED and radiology providers. A total of 3980 CT scans excluding CTAs were ordered with 2240 CTs dedicated to the head and neck, 1685 CTs dedicated to the torso, and 55 CTs dedicated to the extremities. Approximately 74% CT scans were contrast enhanced. Of the 3980 ED CT examination ordered, 69% had a summary code assigned to it. Fifteen percent of the coded CTs had a critical or diagnostic positive result. The introduction of an ED CT summary code did not show a definitive improvement in communication. However, the ED providers are in consensus that radiology reports are crucial their patients' management. There is slightly increased satisfaction with the providers with less than 5 years of experience with the ED CT codes compared to more seasoned providers. The implementation of a user-friendly summary code may allow better analysis of results, practice improvement, and quality measurements in the future.

Diagnostic accuracy of laparoscopy following computed tomography (CT) scanning for assessing the resectability with curative intent in pancreatic and periampullary cancer.

PubMed

Allen, Victoria B; Gurusamy, Kurinchi Selvan; Takwoingi, Yemisi; Kalia, Amun; Davidson, Brian R

2016-07-06

Surgical resection is the only potentially curative treatment for pancreatic and periampullary cancer. A considerable proportion of patients undergo unnecessary laparotomy because of underestimation of the extent of the cancer on computed tomography (CT) scanning. Laparoscopy can detect metastases not visualised on CT scanning, enabling better assessment of the spread of cancer (staging of cancer). This is an update to a previous Cochrane Review published in 2013 evaluating the role of diagnostic laparoscopy in assessing the resectability with curative intent in people with pancreatic and periampullary cancer. To determine the diagnostic accuracy of diagnostic laparoscopy performed as an add-on test to CT scanning in the assessment of curative resectability in pancreatic and periampullary cancer. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via PubMed, EMBASE via OvidSP (from inception to 15 May 2016), and Science Citation Index Expanded (from 1980 to 15 May 2016). We included diagnostic accuracy studies of diagnostic laparoscopy in people with potentially resectable pancreatic and periampullary cancer on CT scan, where confirmation of liver or peritoneal involvement was by histopathological examination of suspicious (liver or peritoneal) lesions obtained at diagnostic laparoscopy or laparotomy. We accepted any criteria of resectability used in the studies. We included studies irrespective of language, publication status, or study design (prospective or retrospective). We excluded case-control studies. Two review authors independently performed data extraction and quality assessment using the QUADAS-2 tool. The specificity of diagnostic laparoscopy in all studies was 1 because there were no false positives since laparoscopy and the reference standard are one and the same if histological examination after diagnostic laparoscopy is positive. The sensitivities were therefore meta-analysed using a univariate random-effects logistic regression model. The probability of unresectability in people who had a negative laparoscopy (post-test probability for people with a negative test result) was calculated using the median probability of unresectability (pre-test probability) from the included studies, and the negative likelihood ratio derived from the model (specificity of 1 assumed). The difference between the pre-test and post-test probabilities gave the overall added value of diagnostic laparoscopy compared to the standard practice of CT scan staging alone. We included 16 studies with a total of 1146 participants in the meta-analysis. Only one study including 52 participants had a low risk of bias and low applicability concern in the patient selection domain. The median pre-test probability of unresectable disease after CT scanning across studies was 41.4% (that is 41 out of 100 participants who had resectable cancer after CT scan were found to have unresectable disease on laparotomy). The summary sensitivity of diagnostic laparoscopy was 64.4% (95% confidence interval (CI) 50.1% to 76.6%). Assuming a pre-test probability of 41.4%, the post-test probability of unresectable disease for participants with a negative test result was 0.20 (95% CI 0.15 to 0.27). This indicates that if a person is said to have resectable disease after diagnostic laparoscopy and CT scan, there is a 20% probability that their cancer will be unresectable compared to a 41% probability for those receiving CT alone.A subgroup analysis of people with pancreatic cancer gave a summary sensitivity of 67.9% (95% CI 41.1% to 86.5%). The post-test probability of unresectable disease after being considered resectable on both CT and diagnostic laparoscopy was 18% compared to 40.0% for those receiving CT alone. Diagnostic laparoscopy may decrease the rate of unnecessary laparotomy in people with pancreatic and periampullary cancer found to have resectable disease on CT scan. On average, using diagnostic laparoscopy with biopsy and histopathological confirmation of suspicious lesions prior to laparotomy would avoid 21 unnecessary laparotomies in 100 people in whom resection of cancer with curative intent is planned.

Single phase computed tomography is equivalent to dual phase method for localizing hyperfunctioning parathyroid glands in patients with primary hyperparathyroidism: a retrospective review

PubMed Central

Morón, Fanny; Delumpa, Alfred; Guffey, Danielle; Dunaway, David

2017-01-01

Objective This study aims to compare the sensitivity of dual phase (non-contrast and arterial) versus single phase (arterial) CT for detection of hyper-functioning parathyroid glands in patients with primary hyperparathyroidism. Methods The CT scans of thirty-two patients who have biochemical evidence of primary hyperparathyroidism, pathologically proven parathyroid adenomas, and pre-operative multiphase parathyroid imaging were evaluated retrospectively in order to compare the adequacy of single phase vs. dual phase CT scans for the detection of parathyroid adenomas. Results The parathyroid adenomas were localized in 83% of cases on single arterial phase CT and 80% of cases on dual phase CT. The specificity for localization of parathyroid tumor was 96% for single phase CT and 97% for dual phase CT. The results were not significantly different (p = 0.695). These results are similar to those found in the literature for multiphase CT of 55–94%. Conclusions Our study supports the use of a single arterial phase CT for the detection of hyperfunctioning parathyroid adenomas. Advances in knowledge: a single arterial phase CT has similar sensitivity for localizing parathyroid adenomas as dual phase CT and significantly reduces radiation dose to the patient. PMID:28828238

Roles of posttherapy 18F-FDG PET/CT in patients with advanced squamous cell carcinoma of the uterine cervix receiving concurrent chemoradiotherapy.

PubMed

Liu, Feng-Yuan; Su, Tzu-Pei; Wang, Chun-Chieh; Chao, Angel; Chou, Hung-Hsueh; Chang, Yu-Chen; Yen, Tzu-Chen; Lai, Chyong-Huey

2018-07-01

To assess the clinical roles of [ 18 F]fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) performed 2-3 months after completion of concurrent chemoradiotherapy (CCRT), along with pretherapy characteristics, in patients with advanced squamous cell carcinoma of the uterine cervix enrolled in a prospective randomized clinical trial. Posttherapy PET/CT in patients with advanced FIGO stage or positive pelvic or para-aortic lymph node (PALN) defined on pretherapy PET/CT was classified as positive, equivocal, or negative. Overall survival (OS) rates between patients with different PET/CT results are compared. Pretherapy characteristics are examined for association with posttherapy PET/CT results and for prognostic significance in patients with equivocal or negative PET/CT. PET/CT scans (n = 55) were positive, equivocal and negative in 9, 13 and 33 patients, respectively. All patients with positive scans were confirmed to have residual or metastatic disease and died despite salvage therapies. There is a significant OS difference between patients with positive and equivocal scans (P < .001) but not between patients with equivocal and negative scans (P = .411). Positive pretherapy PALN is associated with positive posttherapy PET/CT (P = .033) and predicts a poorer survival in patients with equivocal or negative posttherapy PET/CT (P < .001). Positive PET/CT 2-3 months posttherapy implies treatment failure and novel therapy is necessary to improve outcomes for such patients. A more intense posttherapy surveillance may be warranted in patients with positive pretherapy PALN.

Relative hypotension increases the probability of the need for angioembolisation in pelvic fracture patients without contrast extravasation on computed tomography scan.

PubMed

Kuo, Ling-Wei; Yang, Shang-Ju; Fu, Chih-Yuan; Liao, Chien-Hung; Wang, Shang-Yu; Wu, Shih-Chi

2016-01-01

In the evaluation of haemorrhage in trauma patients with pelvic fractures, contrast extravasation (CE) on computed tomography (CT) scan often implies active arterial bleeding. However, the absence of CE on CT scan does not always exclude the need for transcatheter arterial embolisation (TAE) to achieve haemostasis. In the current study, we evaluated the factors associated with the need for TAE in patients without CE on CT scan. These factors may be evaluated as adjuncts to CT scanning in the management of patients with pelvic fractures. We retrospectively reviewed our trauma registry and medical records of patients with pelvic fractures. When CE was observed, indicating active haemorrhage, the patients underwent TAE to achieve haemostasis. In contrast, patients without CE were held for observation and treatment of their injuries, and if their condition deteriorated after a delayed interval, they were then also referred for TAE if no other focus of haemorrhage was found. Patients without CE on CT scan but with retroperitoneal haemorrhage requiring TAE were investigated. Their demographic characteristics, associated injuries, fracture patterns, and changes in systolic blood pressure were described and analysed. In total, 201 patients with pelvic fracture underwent CT scan examination; 47 (23.4%) had CE by CT scan, whereas the other 154 (76.6%) did not. Of the 154 patients who did not show CE by CT scan, 124 (80.5%) patients never underwent TAE; however, 30 (19.5%) of these patients did eventually undergo TAE. In comparing the patients who underwent TAE to those who did not undergo TAE among patients without CE on CT scan, the systolic blood pressure (SBP) on arrival (median: 100.0 mmHg vs 136.0 mmHg, p<0.01) and the lowest SBP recorded in the ED (median: 68.0 mmHg vs 129.0 mmHg, p<0.01) were significantly lower in the patients who underwent TAE. The ROC curve analysis revealed that the most appropriate cutoff value of decrement of SBP (SBP on arrival minus the lowest SBP in the ED) was 30 mmHg (AUC=0.89). In the management of pelvic fracture patients, greater attention should be directed toward patients with relative hypotension. The higher likelihood of haemodynamic deterioration and the need for TAE for haemorrhage control should remain under consideration in such cases, despite the absence of CE by CT scan. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiphase CT scanning and different intravenous contrast media concentrations in combined F-18-FDG PET/CT: Effect on quantitative and clinical assessment.

PubMed

Rebière, Marilou; Verburg, Frederik A; Palmowski, Moritz; Krohn, Thomas; Pietsch, Hubertus; Kuhl, Christiane K; Mottaghy, Felix M; Behrendt, Florian F

2012-08-01

To evaluate the influence of multiphase CT scanning and different intravenous contrast media on contrast enhancement, attenuation correction and image quality in combined PET/CT. 140 patients were prospectively enrolled for F-18-FDG-PET/CT including a low-dose unenhanced, arterial and venous contrast enhanced CT. The first (second) 70 patients, received contrast medium with 370 (300) mg iodine/ml. The iodine delivery rate (1.3mg/s) and total iodine load (44.4g) were identical for both groups. Contrast enhancement and maximum and mean standardized FDG uptake values (SUVmax and SUVmean) were determined for the un-enhanced, arterial and venous PET/CT at multiple anatomic sites and PET reconstructions were visually evaluated. Arterial contrast enhancement was significantly higher for the 300mg/ml contrast medium compared to 370mgI/ml at all anatomic sites. Venous enhancement was not different between the two contrast media. SUVmean and SUVmax were significantly higher for the contrast enhanced compared to the non-enhanced PET/CT at all anatomic sites (all P<0.001). Tracer uptake was significantly higher in the arterial than in the venous PET/CT in the arteries using both contrast media (all P<0.001). No differences in tracer uptake were found between the contrast media (all P>0.05). Visual assessment revealed no relevant differences between the different PET reconstructions. There is no relevant qualitative influence on the PET scan from the use of different intravenous contrast media in its various phases in combined multiphase PET/CT. For quantitative analysis of tracer uptake it is required to use an identical PET/CT protocol. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Refixation of Osteochondral Fractures by an Ultrasound-Activated Pin System - An Ovine In Vivo Examination Using CT and Scanning Electron Microscope.

PubMed

H, Neumann; A P, Schulz; S, Breer; A, Unger; B, Kienast

2015-01-01

Osteochondral injuries, if not treated appropriately, often lead to severe osteoarthritis of the affected joint. Without refixation of the osteochondral fragment, human cartilage only repairs these defects imperfectly. All existing refixation systems for chondral defects have disadvantages, for instance bad MRI quality in the postoperative follow-up or low anchoring forces. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants a higher anchoring is assumed. Aim of the study was to investigate, if ultrasound-activated pins can provide a secure refixation of osteochondral fractures comparing to conventional screw and conventional, resorbable pin osteosynthesis. CT scans and scanning electron microscopy should proovegood refixation results with no further tissue damage by the melting of the ultrasound-activated pins in comparison to conventional osteosynthesis. Femoral osteochondral fragments in sheep were refixated with ultrasound-activated pins (SonicPin™), Ethipins(®) and screws (Asnis™). The quality of the refixated fragments was examined after three month of full weight bearing by CT scans and scanning electron microscopy of the cartilage surface. The CT examination found almost no statistically significant difference in the quality of refixation between the three different implants used. Concerning the CT morphology, ultrasound-activated pins demonstrated at least the same quality in refixation of osteochondral fragments as conventional resorbable pins or screws. The scanning electron microscopy showed no major surface damage by the three implants, especially any postulated cartilage damage induced by the heat of the ultrasound-activated pin. The screws protruded above the cartilage surface, which may affect the opposingtibial surface. Using CT scans and scanning electron microscopy, the SonicPin™, the Ethipin(®) and screws were at least equivalent in refixation quality of osteochondral fragments.

Cancer risk in 680,000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians.

PubMed

Mathews, John D; Forsythe, Anna V; Brady, Zoe; Butler, Martin W; Goergen, Stacy K; Byrnes, Graham B; Giles, Graham G; Wallace, Anthony B; Anderson, Philip R; Guiver, Tenniel A; McGale, Paul; Cain, Timothy M; Dowty, James G; Bickerstaffe, Adrian C; Darby, Sarah C

2013-05-21

To assess the cancer risk in children and adolescents following exposure to low dose ionising radiation from diagnostic computed tomography (CT) scans. Population based, cohort, data linkage study in Australia. COHORT MEMBERS: 10.9 million people identified from Australian Medicare records, aged 0-19 years on 1 January 1985 or born between 1 January 1985 and 31 December 2005; all exposures to CT scans funded by Medicare during 1985-2005 were identified for this cohort. Cancers diagnosed in cohort members up to 31 December 2007 were obtained through linkage to national cancer records. Cancer incidence rates in individuals exposed to a CT scan more than one year before any cancer diagnosis, compared with cancer incidence rates in unexposed individuals. 60,674 cancers were recorded, including 3150 in 680,211 people exposed to a CT scan at least one year before any cancer diagnosis. The mean duration of follow-up after exposure was 9.5 years. Overall cancer incidence was 24% greater for exposed than for unexposed people, after accounting for age, sex, and year of birth (incidence rate ratio (IRR) 1.24 (95% confidence interval 1.20 to 1.29); P<0.001). We saw a dose-response relation, and the IRR increased by 0.16 (0.13 to 0.19) for each additional CT scan. The IRR was greater after exposure at younger ages (P<0.001 for trend). At 1-4, 5-9, 10-14, and 15 or more years since first exposure, IRRs were 1.35 (1.25 to 1.45), 1.25 (1.17 to 1.34), 1.14 (1.06 to 1.22), and 1.24 (1.14 to 1.34), respectively. The IRR increased significantly for many types of solid cancer (digestive organs, melanoma, soft tissue, female genital, urinary tract, brain, and thyroid); leukaemia, myelodysplasia, and some other lymphoid cancers. There was an excess of 608 cancers in people exposed to CT scans (147 brain, 356 other solid, 48 leukaemia or myelodysplasia, and 57 other lymphoid). The absolute excess incidence rate for all cancers combined was 9.38 per 100,000 person years at risk, as of 31 December 2007. The average effective radiation dose per scan was estimated as 4.5 mSv. The increased incidence of cancer after CT scan exposure in this cohort was mostly due to irradiation. Because the cancer excess was still continuing at the end of follow-up, the eventual lifetime risk from CT scans cannot yet be determined. Radiation doses from contemporary CT scans are likely to be lower than those in 1985-2005, but some increase in cancer risk is still likely from current scans. Future CT scans should be limited to situations where there is a definite clinical indication, with every scan optimised to provide a diagnostic CT image at the lowest possible radiation dose.

Efficacy of Positron Emission Tomography/Computed Tomography in Gastric Mucosa-associated Lymphoid Tissue Lymphoma.

PubMed

Hwang, Jin Won; Jee, Sam Ryong; Lee, Sang Heon; Kim, Ji Hyun; Seol, Sang Yong; Lee, Seok Mo

2016-04-25

This study evaluated the diagnostic efficacy of fluorine-18 fluorodeoxyglucose PET/CT (F-18 FDG PET/CT) for patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma and examined the association between FDG avidity and the clinical factors affecting lesions. Among the patients diagnosed with gastric MALT lymphoma, 16 who underwent a PET/CT for gastric MALT lymphoma were semi-quantitatively and qualitatively tested for FDG avidity of lesions in the stomach. Retrospectively collected data was analyzed to investigate the clinicoradiological factors and endoscopic findings between the patients with positive F-18 FDG PET/CT scans and those with negative scans. Eight of the 16 patients showed FDG avidity. When comparing the size of lesions in the stomach, the patients with FDG avidity had significantly larger lesions than those without (28.8 mm vs. 15.0 mm, p=0.03). The FDG-avid group has a significantly higher rate of positive CT scans than the non-avid group (75% vs. 13%, p=0.03). According to the endoscopic finding of the lesions, FDG avidity was pronounced with 75% of the protruding tumors, and 100% of the erosive-ulcerative types, which are a type of depressed tumors. When gastric MALT lymphoma is large, when lesions are found using abdominal CT scans, and the macroscopic appearance of a lesion is that of a protruding tumor or erosive-ulcerative type of depressed tumor, there is a high probability that such patients may have a positive F-18 FDG PET/CT scan.

Personalized assessment of radiation risks from the one-stop-shop myocardial 256-slice CT examination.

PubMed

Perisinakis, Kostas; Seimenis, Ioannis; Tzedakis, Antonis; Pagonidis, Kostas; Papadakis, Antonios E; Damilakis, John

2013-10-15

This study provides data on the cumulative life attributable risk (LAR) of radiation-induced cancer from the combination of coronary CT angiography (CCTA), dynamic CT perfusion (CTP) and delayed enhancement (DE) CT scans, required for reliable risk-benefit analysis of the one-stop-shop CCTA + CTP + DECT cardiac examination. Monte Carlo simulation of the dynamic CTP and DECT exposures on 62 adult individuals was employed to determine radiation absorbed dose to exposed radiosensitive organs. Corresponding data for CCTA were derived using patient chest circumference and previously published data. Individual-specific LARs of cancer were estimated using organ/tissue-specific radiogenic cancer risk factors. Total LAR from CCTA + CTP + DECT scans' sequence were estimated and compared to nominal intrinsic risk of cancer. The main contribution, up to 80%, to cumulative radiation burden from CCTA + CTP + DECT scan-sequence was found to originate from the CTP scan. The total LAR from CCTA + CTP + DECT for females was found 4-6 times higher, compared to males. The mean cumulative risk of radiogenic cancer associated with the complete CCTA + CTP + DECT scan sequence was found to marginally increase the intrinsic risk for cancer induction by less than 0.6% and 0.1% for females and males, respectively. The radiation risk from the 256-slice CCTA + CTP + DECT scan sequence may be considered low and should not constitute an obstacle for the clinical endorsement of the one-stop-shop cardiac CT examination, given that its clinical value has been well verified. Nevertheless, every effort should be made towards optimization of the dynamic CTP component which is the main contributor to patient radiation burden. © 2013.

Body CT (CAT Scan)

MedlinePlus

... Resources Professions Site Index A-Z Computed Tomography (CT) - Body Computed tomography (CT) of the body uses ... of CT Scanning of the Body? What is CT Scanning of the Body? Computed tomography, more commonly ...

Improved image quality and diagnostic potential using ultra-high-resolution computed tomography of the lung with small scan FOV: A prospective study

PubMed Central

Wang, Yali; Hamal, Preeti; You, Xiaofang; Mao, Haixia; Li, Fei; Sun, Xiwen

2017-01-01

The aim of this study was to assess whether CT imaging using an ultra-high-resolution CT (UHRCT) scan with a small scan field of view (FOV) provides higher image quality and helps to reduce the follow-up period compared with a conventional high-resolution CT (CHRCT) scan. We identified patients with at least one pulmonary nodule at our hospital from July 2015 to November 2015. CHRCT and UHRCT scans were conducted in all enrolled patients. Three experienced radiologists evaluated the image quality using a 5-point score and made diagnoses. The paired images were displayed side by side in a random manner and annotations of scan information were removed. The following parameters including image quality, diagnostic confidence of radiologists, follow-up recommendations and diagnostic accuracy were assessed. A total of 52 patients (62 nodules) were included in this study. UHRCT scan provides a better image quality regarding the margin of nodules and solid internal component compared to that of CHRCT (P < 0.05). Readers have higher diagnostic confidence based on the UHRCT images than of CHRCT images (P<0.05). The follow-up recommendations were significantly different between UHRCT and CHRCT images (P<0.05). Compared with the surgical pathological findings, UHRCT had a relative higher diagnostic accuracy than CHRCT (P > 0.05). These findings suggest that the UHRCT prototype scanner provides a better image quality of subsolid nodules compared to CHRCT and contributes significantly to reduce the patients' follow-up period. PMID:28231320

Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms

NASA Astrophysics Data System (ADS)

Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M.; Asma, Evren; Kinahan, Paul E.; De Man, Bruno

2015-09-01

For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition. We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 s. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.043 75 mAs, were investigated. Both the analytical Feldkamp, Davis and Kress (FDK) algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality. With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose levels simulated, sparse view protocols with 41 and 24 views best balanced the tradeoff between electronic noise and aliasing artifacts. In terms of lesion activity error and ensemble RMSE of the PET images, these two protocols, when combined with MBIR, are able to provide results that are comparable to the baseline full dose CT scan. View interpolation significantly improves the performance of FDK reconstruction but was not necessary for MBIR. With the more technically feasible continuous exposure data acquisition, the CT images show an increase in azimuthal blur compared to tube pulsing. However, this blurring generally does not have a measureable impact on PET reconstructed images. Our simulations demonstrated that ultra-low-dose CT-based attenuation correction can be achieved at dose levels on the order of 0.044 mAs with little impact on PET image quality. Highly sparse 41- or 24- view ultra-low dose CT scans are feasible for PET attenuation correction, providing the best tradeoff between electronic noise and view aliasing artifacts. The continuous exposure acquisition mode could potentially be implemented in current commercially available scanners, thus enabling sparse view data acquisition without requiring x-ray tubes capable of operating in a pulsing mode.

Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms

PubMed Central

Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M.; Asma, Evren; Kinahan, Paul E.; De Man, Bruno

2015-01-01

For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition. Methods We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 seconds. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.04375 mAs, were investigated. Both the analytical FDK algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality. Results With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose levels simulated, sparse view protocols with 41 and 24 views best balanced the tradeoff between electronic noise and aliasing artifacts. In terms of lesion activity error and ensemble RMSE of the PET images, these two protocols, when combined with MBIR, are able to provide results that are comparable to the baseline full dose CT scan. View interpolation significantly improves the performance of FDK reconstruction but was not necessary for MBIR. With the more technically feasible continuous exposure data acquisition, the CT images show an increase in azimuthal blur compared to tube pulsing. However, this blurring generally does not have a measureable impact on PET reconstructed images. Conclusions Our simulations demonstrated that ultra-low-dose CT-based attenuation correction can be achieved at dose levels on the order of 0.044 mAs with little impact on PET image quality. Highly sparse 41- or 24- view ultra-low dose CT scans are feasible for PET attenuation correction, providing the best tradeoff between electronic noise and view aliasing artifacts. The continuous exposure acquisition mode could potentially be implemented in current commercially available scanners, thus enabling sparse view data acquisition without requiring x-ray tubes capable of operating in a pulsing mode. PMID:26352168

Development of 1-year-old computational phantom and calculation of organ doses during CT scans using Monte Carlo simulation.

PubMed

Pan, Yuxi; Qiu, Rui; Gao, Linfeng; Ge, Chaoyong; Zheng, Junzheng; Xie, Wenzhang; Li, Junli

2014-09-21

With the rapidly growing number of CT examinations, the consequential radiation risk has aroused more and more attention. The average dose in each organ during CT scans can only be obtained by using Monte Carlo simulation with computational phantoms. Since children tend to have higher radiation sensitivity than adults, the radiation dose of pediatric CT examinations requires special attention and needs to be assessed accurately. So far, studies on organ doses from CT exposures for pediatric patients are still limited. In this work, a 1-year-old computational phantom was constructed. The body contour was obtained from the CT images of a 1-year-old physical phantom and the internal organs were deformed from an existing Chinese reference adult phantom. To ensure the organ locations in the 1-year-old computational phantom were consistent with those of the physical phantom, the organ locations in 1-year-old computational phantom were manually adjusted one by one, and the organ masses were adjusted to the corresponding Chinese reference values. Moreover, a CT scanner model was developed using the Monte Carlo technique and the 1-year-old computational phantom was applied to estimate organ doses derived from simulated CT exposures. As a result, a database including doses to 36 organs and tissues from 47 single axial scans was built. It has been verified by calculation that doses of axial scans are close to those of helical scans; therefore, this database could be applied to helical scans as well. Organ doses were calculated using the database and compared with those obtained from the measurements made in the physical phantom for helical scans. The differences between simulation and measurement were less than 25% for all organs. The result shows that the 1-year-old phantom developed in this work can be used to calculate organ doses in CT exposures, and the dose database provides a method for the estimation of 1-year-old patient doses in a variety of CT examinations.

Development of 1-year-old computational phantom and calculation of organ doses during CT scans using Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Pan, Yuxi; Qiu, Rui; Gao, Linfeng; Ge, Chaoyong; Zheng, Junzheng; Xie, Wenzhang; Li, Junli

2014-09-01

With the rapidly growing number of CT examinations, the consequential radiation risk has aroused more and more attention. The average dose in each organ during CT scans can only be obtained by using Monte Carlo simulation with computational phantoms. Since children tend to have higher radiation sensitivity than adults, the radiation dose of pediatric CT examinations requires special attention and needs to be assessed accurately. So far, studies on organ doses from CT exposures for pediatric patients are still limited. In this work, a 1-year-old computational phantom was constructed. The body contour was obtained from the CT images of a 1-year-old physical phantom and the internal organs were deformed from an existing Chinese reference adult phantom. To ensure the organ locations in the 1-year-old computational phantom were consistent with those of the physical phantom, the organ locations in 1-year-old computational phantom were manually adjusted one by one, and the organ masses were adjusted to the corresponding Chinese reference values. Moreover, a CT scanner model was developed using the Monte Carlo technique and the 1-year-old computational phantom was applied to estimate organ doses derived from simulated CT exposures. As a result, a database including doses to 36 organs and tissues from 47 single axial scans was built. It has been verified by calculation that doses of axial scans are close to those of helical scans; therefore, this database could be applied to helical scans as well. Organ doses were calculated using the database and compared with those obtained from the measurements made in the physical phantom for helical scans. The differences between simulation and measurement were less than 25% for all organs. The result shows that the 1-year-old phantom developed in this work can be used to calculate organ doses in CT exposures, and the dose database provides a method for the estimation of 1-year-old patient doses in a variety of CT examinations.

PET/CT-Based Dosimetry in 90Y-Microsphere Selective Internal Radiation Therapy: Single Cohort Comparison With Pretreatment Planning on (99m)Tc-MAA Imaging and Correlation With Treatment Efficacy.

PubMed

Song, Yoo Sung; Paeng, Jin Chul; Kim, Hyo-Cheol; Chung, Jin Wook; Cheon, Gi Jeong; Chung, June-Key; Lee, Dong Soo; Kang, Keon Wook

2015-06-01

⁹⁰Y PET/CT can be acquired after ⁹⁰Y-microsphere selective radiation internal therapy (SIRT) to describe radioactivity distribution. We performed dosimetry using ⁹⁰Y-microsphere PET/CT data to evaluate treatment efficacy and appropriateness of activity planning from (99m)Tc-MAA scan and SPECT/CT. Twenty-three patients with liver malignancy were included in the study. (99m)Tc-MAA was injected during planning angiography and whole body (99m)Tc-MAA scan and liver SPECT/CT were acquired. After SIRT using ⁹⁰Y-resin microsphere, ⁹⁰Y-microsphere PET/CT was acquired. A partition model (PM) using 4 compartments (tumor, intarget normal liver, out-target normal liver, and lung) was adopted, and absorbed dose to each compartment was calculated based on measurements from (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT, respectively, to be compared with each other. Progression-free survival (PFS) was evaluated in terms of tumor absorbed doses calculated by (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT results. Lung shunt fraction was overestimated on (99m)Tc-MAA scan compared with ⁹⁰Y-microsphere PET/CT (0.060 ± 0.037 vs. 0.018 ± 0.026, P < 0.01). Tumor absorbed dose exhibited a close correlation between the results from (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT (r = 0.64, P < 0.01), although the result from (99m)Tc-MAA SPECT/CT was significantly lower than that from ⁹⁰Y-microsphere PET/CT (135.4 ± 64.2 Gy vs. 185.0 ± 87.8 Gy, P < 0.01). Absorbed dose to in-target normal liver was overestimated on (99m)Tc-MAA SPECT/CT compared with PET/CT (62.6 ± 38.2 Gy vs. 45.2 ± 32.0 Gy, P = 0.02). Absorbed dose to out-target normal liver did not differ between (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT (P = 0.49). Patients with tumor absorbed dose >200 Gy on ⁹⁰Y-microsphere PET/CT had longer PFS than those with tumor absorbed dose ≤200 Gy (286 ± 56 days vs. 92 ± 20 days, P = 0.046). Tumor absorbed dose calculated by (99m)Tc-MAA SPECT/CT was not a significant predictor for PFS. Activity planning based on (99m)Tc-MAA scan and SPECT/CT can be effectively used as a conservative method. Post-SIRT dosimetry based on ⁹⁰Y-microsphere PET/CT is an effective method to predict treatment efficacy.

PET/CT-Based Dosimetry in 90Y-Microsphere Selective Internal Radiation Therapy: Single Cohort Comparison With Pretreatment Planning on 99mTc-MAA Imaging and Correlation With Treatment Efficacy

PubMed Central

Song, Yoo Sung; Paeng, Jin Chul; Kim, Hyo-Cheol; Chung, Jin Wook; Cheon, Gi Jeong; Chung, June-Key; Lee, Dong Soo; Kang, Keon Wook

2015-01-01

Abstract 90Y PET/CT can be acquired after 90Y-microsphere selective radiation internal therapy (SIRT) to describe radioactivity distribution. We performed dosimetry using 90Y-microsphere PET/CT data to evaluate treatment efficacy and appropriateness of activity planning from 99mTc-MAA scan and SPECT/CT. Twenty-three patients with liver malignancy were included in the study. 99mTc-MAA was injected during planning angiography and whole body 99mTc-MAA scan and liver SPECT/CT were acquired. After SIRT using 90Y-resin microsphere, 90Y-microsphere PET/CT was acquired. A partition model (PM) using 4 compartments (tumor, intarget normal liver, out-target normal liver, and lung) was adopted, and absorbed dose to each compartment was calculated based on measurements from 99mTc-MAA SPECT/CT and 90Y-microsphere PET/CT, respectively, to be compared with each other. Progression-free survival (PFS) was evaluated in terms of tumor absorbed doses calculated by 99mTc-MAA SPECT/CT and 90Y-microsphere PET/CT results. Lung shunt fraction was overestimated on 99mTc-MAA scan compared with 90Y-microsphere PET/CT (0.060 ± 0.037 vs. 0.018 ± 0.026, P < 0.01). Tumor absorbed dose exhibited a close correlation between the results from 99mTc-MAA SPECT/CT and 90Y-microsphere PET/CT (r = 0.64, P < 0.01), although the result from 99mTc-MAA SPECT/CT was significantly lower than that from 90Y-microsphere PET/CT (135.4 ± 64.2 Gy vs. 185.0 ± 87.8 Gy, P < 0.01). Absorbed dose to in-target normal liver was overestimated on 99mTc-MAA SPECT/CT compared with PET/CT (62.6 ± 38.2 Gy vs. 45.2 ± 32.0 Gy, P = 0.02). Absorbed dose to out-target normal liver did not differ between 99mTc-MAA SPECT/CT and 90Y-microsphere PET/CT (P = 0.49). Patients with tumor absorbed dose >200 Gy on 90Y-microsphere PET/CT had longer PFS than those with tumor absorbed dose ≤200 Gy (286 ± 56 days vs. 92 ± 20 days, P = 0.046). Tumor absorbed dose calculated by 99mTc-MAA SPECT/CT was not a significant predictor for PFS. Activity planning based on 99mTc-MAA scan and SPECT/CT can be effectively used as a conservative method. Post-SIRT dosimetry based on 90Y-microsphere PET/CT is an effective method to predict treatment efficacy. PMID:26061323

High energy x-ray phase contrast CT using glancing-angle grating interferometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarapata, A., E-mail: adrian.sarapata@tum.de; Stayman, J. W.; Siewerdsen, J. H.

Purpose: The authors present initial progress toward a clinically compatible x-ray phase contrast CT system, using glancing-angle x-ray grating interferometry to provide high contrast soft tissue images at estimated by computer simulation dose levels comparable to conventional absorption based CT. Methods: DPC-CT scans of a joint phantom and of soft tissues were performed in order to answer several important questions from a clinical setup point of view. A comparison between high and low fringe visibility systems is presented. The standard phase stepping method was compared with sliding window interlaced scanning. Using estimated dose values obtained with a Monte-Carlo code themore » authors studied the dependence of the phase image contrast on exposure time and dose. Results: Using a glancing angle interferometer at high x-ray energy (∼45 keV mean value) in combination with a conventional x-ray tube the authors achieved fringe visibility values of nearly 50%, never reported before. High fringe visibility is shown to be an indispensable parameter for a potential clinical scanner. Sliding window interlaced scanning proved to have higher SNRs and CNRs in a region of interest and to also be a crucial part of a low dose CT system. DPC-CT images of a soft tissue phantom at exposures in the range typical for absorption based CT of musculoskeletal extremities were obtained. Assuming a human knee as the CT target, good soft tissue phase contrast could be obtained at an estimated absorbed dose level around 8 mGy, similar to conventional CT. Conclusions: DPC-CT with glancing-angle interferometers provides improved soft tissue contrast over absorption CT even at clinically compatible dose levels (estimated by a Monte-Carlo computer simulation). Further steps in image processing, data reconstruction, and spectral matching could make the technique fully clinically compatible. Nevertheless, due to its increased scan time and complexity the technique should be thought of not as replacing, but as complimentary to conventional CT, to be used in specific applications.« less

SU-E-J-220: Assessment of MRI Geometric Distortion in Head and Neck Cancer Patients Scanned in Immobilized Radiation Treatment Position

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, C; Mohamed, A; Weygand, J

2015-06-15

Purpose: Uncertainties about geometric distortion have somewhat hindered MRI simulation in radiation therapy. Most of the geometric distortion studies were performed with phantom measurements but another major aspect of MR distortion is patient related. We studied the geometric distortion in patient images by comparing their MRI scans with the corresponding CT, using CT as the non-distorted gold standard. Methods: Ten H&N cancer patients were imaged with MRI as part of a prospective IRB approved study. All patients had their treatment planning CT done on the same day or within one week of the MRI. MR Images were acquired with amore » T2 SE sequence (1×1×2.5mm voxel size) in the same immobilization position as in the CT scans. MRI to CT rigid registration was then done and geometric distortion comparison was done by measuring the corresponding anatomical landmarks on both the MRI and the CT images by two observers. Several skin to skin (9 landmarks), bone to bone (8 landmarks), and soft tissue (3 landmarks) were measured at specific levels in horizontal and vertical planes of both scans. Results: The mean distortion for all landmark measurements in all scans was 1.8±1.9mm. For each patient 11 measurements were done in the horizontal plane while 9 were done in the vertical plane. The measured geometric distortion were significantly lower in the horizontal axis compared to the vertical axis (1.3±0.16 mm vs 2.2±0.19 mm, respectively, P=0.003*). The magnitude of distortion was lower in the bone to bone landmarks compared to the combined soft tissue and skin to skin landmarks (1.2±0.19 mm vs 2.3±0.17 mm, P=0.0006*). The mean distortion measured by observer one was not significantly different compared toobserver 2 (2.3 vs 2.4 mm, P=0.4). Conclusion: MRI geometric distortions were quantified in H&N patients with mean error of less than 2 mm. JW received a corporate sponsored research grant from Elekta.« less

Monte Carlo simulations of adult and pediatric computed tomography exams: Validation studies of organ doses with physical phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Daniel J.; Lee, Choonsik; Tien, Christopher

2013-01-15

Purpose: To validate the accuracy of a Monte Carlo source model of the Siemens SOMATOM Sensation 16 CT scanner using organ doses measured in physical anthropomorphic phantoms. Methods: The x-ray output of the Siemens SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code, MCNPX version 2.6. The resulting source model was able to perform various simulated axial and helical computed tomographic (CT) scans of varying scan parameters, including beam energy, filtration, pitch, and beam collimation. Two custom-built anthropomorphic phantoms were used to take dose measurements on the CT scanner: an adult male and amore » 9-month-old. The adult male is a physical replica of University of Florida reference adult male hybrid computational phantom, while the 9-month-old is a replica of University of Florida Series B 9-month-old voxel computational phantom. Each phantom underwent a series of axial and helical CT scans, during which organ doses were measured using fiber-optic coupled plastic scintillator dosimeters developed at University of Florida. The physical setup was reproduced and simulated in MCNPX using the CT source model and the computational phantoms upon which the anthropomorphic phantoms were constructed. Average organ doses were then calculated based upon these MCNPX results. Results: For all CT scans, good agreement was seen between measured and simulated organ doses. For the adult male, the percent differences were within 16% for axial scans, and within 18% for helical scans. For the 9-month-old, the percent differences were all within 15% for both the axial and helical scans. These results are comparable to previously published validation studies using GE scanners and commercially available anthropomorphic phantoms. Conclusions: Overall results of this study show that the Monte Carlo source model can be used to accurately and reliably calculate organ doses for patients undergoing a variety of axial or helical CT examinations on the Siemens SOMATOM Sensation 16 scanner.« less

TU-EF-204-07: Add Tube Current Modulation to a Low Dose Simulation Tool for CT Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Y.; Department of Physics, University of Arizona, Tucson, AZ; Wen, G.

2015-06-15

Purpose: We extended the capabilities of a low dose simulation tool to model Tube-Current Modulation (TCM). TCM is widely used in clinical practice to reduce radiation dose in CT scans. We expect the tool to be valuable for various clinical applications (e.g., optimize protocols, compare reconstruction techniques and evaluate TCM methods). Methods: The tube current is input as a function of z location, instead of a fixed value. Starting from the line integrals of a scan, a new Poisson noise realization at a lower dose is generated for each view. To validate the new functionality, we compared simulated scans withmore » real scans in image space. Results: First we assessed noise in the difference between the low-dose simulations and the original high-dose scan. When the simulated tube current is a step function of z location, the noise at each segment matches the noise of 3 separate constant-tube-current-simulations. Secondly, with a phantom that forces TCM, we compared a low-dose simulation with an equivalent real low-dose scan. The mean CT number of the simulated scan and the real low-dose scan were 137.7±0.6 and 137.8±0.5 respectively. Furthermore, with 240 ROIs, the noise of the simulated scan and the real low-dose scan were 24.03±0.45 and 23.99±0.43 respectively, and they were not statistically different (2-sample t-test, p-value=0.28). The facts that the noise reflected the trend of the TCM curve, and that the absolute noise measurements were not statistically different validated the TCM function. Conclusion: We successfully added tube-current modulation functionality in an existing low dose simulation tool. We demonstrated that the noise reflected an input tube-current modulation curve. In addition, we verified that the noise and mean CT number of our simulation agreed with a real low dose scan. The authors are all employees of Philips. Yijun Ding is also supported by NIBIB P41EB002035 and NIBIB R01EB000803.« less

Routine postoperative CT-scans after burr hole trepanation for chronic subdural hematoma - better before or after drainage removal?

PubMed

Brokinkel, Benjamin; Ewelt, Christian; Holling, Markus; Hesselmann, Volker; Heindel, Walter Leonard; Stummer, Walter; Fischer, Bernhard Robert

2013-01-01

To evaluate timing of scheduled CT-scans after burr hole trepanation for chronic subdural hematoma (cSDH). 131 patients with primary cSDH were included. Scheduled CT-scans were performed after burr hole trepanation and placement of a subdural drain. The influence of CT-scanning with or without indwelling drain was analysed regarding subsequent surgery and CT-scans, duration of hospitalization, short- and middle-term follow up by single factor analyses. Subgroup analyses were performed for patients receiving anticoagulant drugs. Median age was 74 years. Routine CT-scans with indwelling drainage were not shown to be beneficial regarding subsequent burr hole trepanations (p=0.243), craniotomies (p=1.000) and outcome at discharge (p=0.297). Mean duration of hospitalization (11 vs. 8 days, p=0.013) was significantly longer and number of subsequent CT-scans was higher when CT scan was performed with indwelling drain (2.3 vs. 1.4, p=0.001). In middle-term follow-up, beneficial effects of CT-scanning with inlaying drainage could neither be shown. Moreover, advantageous effects of CT-scans with indwelling drains could neither be shown for patients receiving anticoagulant drugs. Scheduled postoperative cranial imaging with indwelling drains was not shown to be beneficial and misses information of intracranial damage inflicted by removal of drains. We thus recommend CT-scanning after drainage removal.

An open library of CT patient projection data

NASA Astrophysics Data System (ADS)

Chen, Baiyu; Leng, Shuai; Yu, Lifeng; Holmes, David; Fletcher, Joel; McCollough, Cynthia

2016-03-01

Lack of access to projection data from patient CT scans is a major limitation for development and validation of new reconstruction algorithms. To meet this critical need, we are building a library of CT patient projection data in an open and vendor-neutral format, DICOM-CT-PD, which is an extended DICOM format that contains sinogram data, acquisition geometry, patient information, and pathology identification. The library consists of scans of various types, including head scans, chest scans, abdomen scans, electrocardiogram (ECG)-gated scans, and dual-energy scans. For each scan, three types of data are provided, including DICOM-CT-PD projection data at various dose levels, reconstructed CT images, and a free-form text file. Several instructional documents are provided to help the users extract information from DICOM-CT-PD files, including a dictionary file for the DICOM-CT-PD format, a DICOM-CT-PD reader, and a user manual. Radiologist detection performance based on the reconstructed CT images is also provided. So far 328 head cases, 228 chest cases, and 228 abdomen cases have been collected for potential inclusion. The final library will include a selection of 50 head, chest, and abdomen scans each from at least two different manufacturers, and a few ECG-gated scans and dual-source, dual-energy scans. It will be freely available to academic researchers, and is expected to greatly facilitate the development and validation of CT reconstruction algorithms.

A comparative study on the CT effective dose for various positions of the patient's arm

NASA Astrophysics Data System (ADS)

Seong, Ji-Hye; Park, Soon-Ki; Kim, Jung-Sun; Jung, Woo-Young; Kim, Ho-Sung; Dong, Kyung-Rae; Chung, Woon-Kwan; Cho, Jae-Hwan; Cho, Young-Kuk

2012-10-01

In a whole body PET/CT (positron emission tomography/computed tomography) scan, lifting the patient's arm to improve the image quality is natural. On the other hand, the arms should be placed lower when the lesion is located in the head and neck. This study compared the CT effective dose for each arm position after applying AEC (automatic exposure control). Forty-five patients who had undergone an 18F-FDG (fluorine-18-fluoro deoxy glucose) whole body PET/CT scan were examined using Biograph Truepoint 40, Biograph Sensation 16, and Discovery STe 8 systems. The CT effective dose of 15 patients for each set of equipment was measured and analyzed comparatively in both the arm-lifted and arm-lowered positions. The ImPACT Ver. 1.0 program was used to measure the CT effective dose. A paired t-test (SPSS 18.0 statistic program) was applied for statistical analysis. In the case of the arm-lifted position, the CT effective dose measured for Biograph 40, Biograph 16, and DSTe 8 systems were 6.33 ± 0.93 mSv, 8.01 ± 1.34 mSv, and 9.69 ± 2.32 mSv, respectively. When the arms were located in the lower position, the respective CT effective doses were 6.97 ± 0.76 mSv, 8.95 ± 1.85 mSv, and 13.07 ± 2.87 mSv, respectively. These results revealed 9.2%, 10.5%, and 25.9% improvement in the CT effective doses for the Biograph 40, Biograph 16 and DSTe 8 systems, respectively, when the arms were raised compared to that when they were lowered (p < 0.05). For the whole body PET/CT case, the CT effective dose applying AEC showed a mean 15.2% decrease in the radiation exposure of the patients when the arm was lifted. The patient with no lesion in the head and neck would show fewer artifacts in the objective part and a lower CT effective dose. For a patient with a lesion in the head and neck, the artifacts in the objective part can be reduced by putting the arms down. The fact that the CT effective dose is increased in a whole-body PET/CT scan should be a concern.

An Indirect Method to Measure Abutment Screw Preload: A Pilot Study Based on Micro-CT Scanning.

PubMed

Rezende, Carlos Eduardo E; Griggs, Jason Alan; Duan, Yuanyuan; Mushashe, Amanda M; Nolasco, Gisele Maria Correr; Borges, Ana Flávia Sanches; Rubo, José Henrique

2015-01-01

This study aimed to measure the preload in different implant platform geometries based on micro-CT images. External hexagon (EH) implants and Morse Tapered (MT) implants (n=5) were used for the preload measurement. The abutment screws were scanned in micro-CT to obtain their virtual models, which were used to record their initial length. The abutments were screwed on the implant with a 20 Ncm torque and the set composed by implant, abutment screw and abutment were taken to the micro-CT scanner to obtain virtual slices of the specimens. These slices allowed the measurement of screw lengths after torque application and based on the screw elongation. Preload values were calculated using the Hooke's Law. The preloads of both groups were compared by independent t-test. Removal torque of each specimen was recorded. To evaluate the accuracy of the micro-CT technique, three rods with known lengths were scanned and the length of their virtual model was measured and compared with the original length. One rod was scanned four times to evaluate the measuring method variation. There was no difference between groups for preload (EH = 461.6 N and MT = 477.4 N), but the EH group showed higher removal torque values (13.8 ± 4.7 against 8.2 ± 3.6 N cm for MT group). The micro-CT technique showed a variability of 0.053% and repeatability showed an error of 0.23 to 0.28%. Within the limitations of this study, there was no difference between external hexagon and Morse taper for preload. The method using micro-CT may be considered for preload calculation.

Chest ultrasonography in health surveillance of asbestos-related lung diseases.

PubMed

Smargiassi, Andrea; Pasciuto, Giuliana; Pedicelli, Ilaria; Lo Greco, Erminia; Calvello, Mariarosaria; Inchingolo, Riccardo; Schifino, Gioacchino; Capoluongo, Patrizio; Patriciello, Pasquale; Manno, Maurizio; Cirillo, Alfonso; Corbo, Giuseppe Maria; Soldati, Gino; Iavicoli, Ivo

2017-06-01

Exposure to asbestos fibers can lead to different lung diseases, such as pleural thickening and effusion, asbestosis, mesothelioma, and lung cancer. These diseases are expected to peak in the next few years. The aim of the study was to validate ultrasonography (US) as a diagnostic tool in the management of lung diseases in subjects with a history of occupational exposure to asbestos. Fifty-nine retired male workers previously exposed to asbestos were enrolled in the study. Chest US was performed in all the subjects. The US operator was blinded to earlier performed computed tomography (CT) scan reports and images. The sonographic pathological findings were pleural thickening (with or without calcifications), peripheral lung consolidation, and focal sonographic interstitial syndrome and diffuse pneumogenic sonographic interstitial syndrome (pulmonary asbestosis). Significant US findings were recorded, stored, and subsequently compared with CT scans. With some patients falling into more than one category, on CT scan, pleural thickening was reported in 33 cases (56%, 26 with calcifications), focal interstitial peripheral alterations in 23 (39%), asbestosis in 6 (10%), and peripheral lung consolidation in 13 cases (22%). Comparing each pathological condition to CT scan reports, US findings had high levels of sensitivity, specificity, positive, and negative predictive values. US did not prove effective for the detection of central lung nodules or diaphragmatic pleural thickenings. Chest US was considered to be the best technique to detect minimal pleural effusions (six subjects, 10%). Chest US might be considered an additional tool to follow up subjects occupationally exposed to asbestos who have already undergone CT scan examination and whose pathology is detectable by US as well.

A prototype table-top inverse-geometry volumetric CT system.

PubMed

Schmidt, Taly Gilat; Star-Lack, Josh; Bennett, N Robert; Mazin, Samuel R; Solomon, Edward G; Fahrig, Rebecca; Pelc, Norbert J

2006-06-01

A table-top volumetric CT system has been implemented that is able to image a 5-cm-thick volume in one circular scan with no cone-beam artifacts. The prototype inverse-geometry CT (IGCT) scanner consists of a large-area, scanned x-ray source and a detector array that is smaller in the transverse direction. The IGCT geometry provides sufficient volumetric sampling because the source and detector have the same axial, or slice direction, extent. This paper describes the implementation of the table-top IGCT scanner, which is based on the NexRay Scanning-Beam Digital X-ray system (NexRay, Inc., Los Gatos, CA) and an investigation of the system performance. The alignment and flat-field calibration procedures are described, along with a summary of the reconstruction algorithm. The resolution and noise performance of the prototype IGCT system are studied through experiments and further supported by analytical predictions and simulations. To study the presence of cone-beam artifacts, a "Defrise" phantom was scanned on both the prototype IGCT scanner and a micro CT system with a +/-5 cone angle for a 4.5-cm volume thickness. Images of inner ear specimens are presented and compared to those from clinical CT systems. Results showed that the prototype IGCT system has a 0.25-mm isotropic resolution and that noise comparable to that from a clinical scanner with equivalent spatial resolution is achievable. The measured MTF and noise values agreed reasonably well with theoretical predictions and computer simulations. The IGCT system was able to faithfully reconstruct the laminated pattern of the Defrise phantom while the micro CT system suffered severe cone-beam artifacts for the same object. The inner ear acquisition verified that the IGCT system can image a complex anatomical object, and the resulting images exhibited more high-resolution details than the clinical CT acquisition. Overall, the successful implementation of the prototype system supports the IGCT concept for single-rotation volumetric scanning free from cone-beam artifacts.

The Necessity of Follow-Up Brain Computed-Tomography Scans: Is It the Pathology Itself Or Our Fear that We Should Overcome?

PubMed Central

Öğrenci, Ahmet; Koban, Orkun; Ekşi, Murat; Yaman, Onur; Dalbayrak, Sedat

2017-01-01

AIM: This study aimed to make a retrospective analysis of pediatric patients with head traumas that were admitted to one hospital setting and to make an analysis of the patients for whom follow-up CT scans were obtained. METHODS: Pediatric head trauma cases were retrospectively retrieved from the hospital’s electronic database. Patients’ charts, CT scans and surgical notes were evaluated by one of the authors. Repeat CT scans for operated patients were excluded from the total number of repeat CT scans. RESULTS: One thousand one hundred and thirty-eight pediatric patients were admitted to the clinic due to head traumas. Brain CT scan was requested in 863 patients (76%) in the cohort. Follow-up brain CT scans were obtained in 102 patients. Additional abnormal finding requiring surgical intervention was observed in only one patient (isolated 4th ventricle hematoma) on the control CTs (1% of repeat CT scans), who developed obstructive hydrocephalus. None of the patients with no more than 1 cm epidural hematoma in its widest dimension and repeat CT scans obtained 1.5 hours after the trauma necessitated surgery. CONCLUSION: Follow-up CT scans changed clinical approach in only one patient in the present series. When ordering CT scan in the follow-up of pediatric traumas, benefits and harms should be weighted based upon time interval from trauma onset to initial CT scan and underlying pathology. PMID:29104682

Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: image reconstruction and assessment of image quality.

PubMed

Flohr, Thomas G; Leng, Shuai; Yu, Lifeng; Aiimendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H

2009-12-01

To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. No significant differences in quantitative measures of image quality were found between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6 pitch 3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch = 3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving coronary artery phantom acquired with the ECG-triggered high-pitch scan mode were visually free from motion artifacts at heart rates of 60 and 70 bpm. However, image quality started to deteriorate for higher heart rates. At equivalent image quality, the ECG-triggered high-pitch scan mode demonstrated lower radiation dose than other cardiac scan techniques on the same DSCT equipment (25% and 60% dose reduction compared to ECG-triggered sequential step-and-shoot and ECG-gated spiral with x-ray pulsing). A high-pitch (up to pitch = 3.2), high-temporal-resolution (up to 75 ms) dual-source CT scan mode produced equivalent image quality relative to single-source scans using a more typical pitch value (pitch = 1.0). The resultant reduction in the overall acquisition time may offer clinical advantage for cardiovascular, trauma, and pediatric CT applications. In addition, ECG-triggered high-pitch scanning may be useful as an alternative to ECG-triggered sequential scanning for patients with low to moderate heart rates up to 70 bpm, with the potential to scan the heart within one heart beat at reduced radiation dose.

Optimization of the scan protocols for CT-based material extraction in small animal PET/CT studies

NASA Astrophysics Data System (ADS)

Yang, Ching-Ching; Yu, Jhih-An; Yang, Bang-Hung; Wu, Tung-Hsin

2013-12-01

We investigated the effects of scan protocols on CT-based material extraction to minimize radiation dose while maintaining sufficient image information in small animal studies. The phantom simulation experiments were performed with the high dose (HD), medium dose (MD) and low dose (LD) protocols at 50, 70 and 80 kVp with varying mA s. The reconstructed CT images were segmented based on Hounsfield unit (HU)-physical density (ρ) calibration curves and the dual-energy CT-based (DECT) method. Compared to the (HU;ρ) method performed on CT images acquired with the 80 kVp HD protocol, a 2-fold improvement in segmentation accuracy and a 7.5-fold reduction in radiation dose were observed when the DECT method was performed on CT images acquired with the 50/80 kVp LD protocol, showing the possibility to reduce radiation dose while achieving high segmentation accuracy.

Intra-patient comparison of reduced-dose model-based iterative reconstruction with standard-dose adaptive statistical iterative reconstruction in the CT diagnosis and follow-up of urolithiasis.

PubMed

Tenant, Sean; Pang, Chun Lap; Dissanayake, Prageeth; Vardhanabhuti, Varut; Stuckey, Colin; Gutteridge, Catherine; Hyde, Christopher; Roobottom, Carl

2017-10-01

To evaluate the accuracy of reduced-dose CT scans reconstructed using a new generation of model-based iterative reconstruction (MBIR) in the imaging of urinary tract stone disease, compared with a standard-dose CT using 30% adaptive statistical iterative reconstruction. This single-institution prospective study recruited 125 patients presenting either with acute renal colic or for follow-up of known urinary tract stones. They underwent two immediately consecutive scans, one at standard dose settings and one at the lowest dose (highest noise index) the scanner would allow. The reduced-dose scans were reconstructed using both ASIR 30% and MBIR algorithms and reviewed independently by two radiologists. Objective and subjective image quality measures as well as diagnostic data were obtained. The reduced-dose MBIR scan was 100% concordant with the reference standard for the assessment of ureteric stones. It was extremely accurate at identifying calculi of 3 mm and above. The algorithm allowed a dose reduction of 58% without any loss of scan quality. A reduced-dose CT scan using MBIR is accurate in acute imaging for renal colic symptoms and for urolithiasis follow-up and allows a significant reduction in dose. • MBIR allows reduced CT dose with similar diagnostic accuracy • MBIR outperforms ASIR when used for the reconstruction of reduced-dose scans • MBIR can be used to accurately assess stones 3 mm and above.

Electronic noise in CT detectors: Impact on image noise and artifacts.

PubMed

Duan, Xinhui; Wang, Jia; Leng, Shuai; Schmidt, Bernhard; Allmendinger, Thomas; Grant, Katharine; Flohr, Thomas; McCollough, Cynthia H

2013-10-01

The objective of our study was to evaluate in phantoms the differences in CT image noise and artifact level between two types of commercial CT detectors: one with distributed electronics (conventional) and one with integrated electronics intended to decrease system electronic noise. Cylindric water phantoms of 20, 30, and 40 cm in diameter were scanned using two CT scanners, one equipped with integrated detector electronics and one with distributed detector electronics. All other scanning parameters were identical. Scans were acquired at four tube potentials and 10 tube currents. Semianthropomorphic phantoms were scanned to mimic the shoulder and abdominal regions. Images of two patients were also selected to show the clinical values of the integrated detector. Reduction of image noise with the integrated detector depended on phantom size, tube potential, and tube current. Scans that had low detected signal had the greatest reductions in noise, up to 40% for a 30-cm phantom scanned using 80 kV. This noise reduction translated into up to 50% in dose reduction to achieve equivalent image noise. Streak artifacts through regions of high attenuation were reduced by up to 45% on scans obtained using the integrated detector. Patient images also showed superior image quality for the integrated detector. For the same applied radiation level, the use of integrated electronics in a CT detector showed a substantially reduced level of electronic noise, resulting in reductions in image noise and artifacts, compared with detectors having distributed electronics.

Uncertainties in estimating heart doses from 2D-tangential breast cancer radiotherapy.

PubMed

Lorenzen, Ebbe L; Brink, Carsten; Taylor, Carolyn W; Darby, Sarah C; Ewertz, Marianne

2016-04-01

We evaluated the accuracy of three methods of estimating radiation dose to the heart from two-dimensional tangential radiotherapy for breast cancer, as used in Denmark during 1982-2002. Three tangential radiotherapy regimens were reconstructed using CT-based planning scans for 40 patients with left-sided and 10 with right-sided breast cancer. Setup errors and organ motion were simulated using estimated uncertainties. For left-sided patients, mean heart dose was related to maximum heart distance in the medial field. For left-sided breast cancer, mean heart dose estimated from individual CT-scans varied from <1Gy to >8Gy, and maximum dose from 5 to 50Gy for all three regimens, so that estimates based only on regimen had substantial uncertainty. When maximum heart distance was taken into account, the uncertainty was reduced and was comparable to the uncertainty of estimates based on individual CT-scans. For right-sided breast cancer patients, mean heart dose based on individual CT-scans was always <1Gy and maximum dose always <5Gy for all three regimens. The use of stored individual simulator films provides a method for estimating heart doses in left-tangential radiotherapy for breast cancer that is almost as accurate as estimates based on individual CT-scans. Copyright © 2016. Published by Elsevier Ireland Ltd.

Over-scanning in chest CT: Comparison of practice among six hospitals and its impact on radiation dose.

PubMed

Schwartz, Fides; Stieltjes, Bram; Szucs-Farkas, Zsolt; Euler, André

2018-05-01

Compare incidence of over-scanning in chest CT among six hospitals and impact on effective and organ effective radiation dose. Scout images of 600 chest CTs from six hospitals (A-F) were retrospectively reviewed using a radiation dose tracking software (RTS). Optimal scan range was determined and compared to the actual scan range. Incidence of cranial and caudal over-scanning was assessed and changes in total and organ effective dose were calculated. Descriptive statistics, Tukey- and Wilcoxon matched pairs test were applied. Simultaneous cranial and caudal over-scanning occurred in 29 of 600 scans (A = 0%, B = 1%, C = 12%, D = 3%, E = 11%, F = 2%). Effective radiation dose increased on average by 0.29 mSv (P < 0.001). Cranial over-scanning was observed in 45 of 600 scans (A = 0%, B = 8%, C = 2%, D = 15%, E = 17%, F = 3%) and increased organ effective dose by 0.35 mSv in the thyroid gland (P < 0.001). Caudal over-scanning occurred in 147 of 600 scans (A = 7%, B = 9%, C = 35%, D = 4%, E = 32%, F = 60%) and increased organ effective doses in the upper abdomen by up to 14% (P < 0.001 for all organs). Substantial differences in the incidence of over-scanning in chest CT exist among different hospitals. These differences result in excessive effective radiation dose and increased individual organ effective doses in patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Sensitivity of Noncontrast Computed Tomography for Small Renal Calculi With Endoscopy as the Gold Standard.

PubMed

Bhojani, Naeem; Paonessa, Jessica E; El Tayeb, Marawan M; Williams, James C; Hameed, Tariq A; Lingeman, James E

2018-04-03

To compare the sensitivity of noncontrast computed tomography (CT) with endoscopy for detection of renal calculi. Imaging modalities for detection of nephrolithiasis have centered on abdominal x-ray, ultrasound, and noncontrast CT. Sensitivities of 58%-62% (abdominal x-ray), 45% (ultrasound), and 95%-100% (CT) have been previously reported. However, these results have never been correlated with endoscopic findings. Idiopathic calcium oxalate stone formers with symptomatic calculi requiring ureteroscopy were studied. At the time of surgery, the number and the location of all calculi within the kidney were recorded followed by basket retrieval. Each calculus was measured and sent for micro-CT and infrared spectrophotometry. All CT scans were reviewed by the same genitourinary radiologist who was blinded to the endoscopic findings. The radiologist reported on the number, location, and size of each calculus. Eighteen renal units were studied in 11 patients. Average time from CT scan to ureteroscopy was 28.6 days. The mean number of calculi identified per kidney was 9.2 ± 6.1 for endoscopy and 5.9 ± 4.1 for CT (P <.004). The mean size of total renal calculi (sum of the longest stone diameters) per kidney was 22.4 ± 17.1 mm and 18.2 ± 13.2 mm for endoscopy and CT, respectively (P = .06). CT scan underreports the number of renal calculi, probably missing some small stones and being unable to distinguish those lying in close proximity to one another. However, the total stone burden seen by CT is, on average, accurate when compared with that found on endoscopic examination. Copyright © 2018 Elsevier Inc. All rights reserved.

Multi-Mounted X-Ray Computed Tomography

PubMed Central

Fu, Jian; Liu, Zhenzhong; Wang, Jingzheng

2016-01-01

Most existing X-ray computed tomography (CT) techniques work in single-mounted mode and need to scan the inspected objects one by one. It is time-consuming and not acceptable for the inspection in a large scale. In this paper, we report a multi-mounted CT method and its first engineering implementation. It consists of a multi-mounted scanning geometry and the corresponding algebraic iterative reconstruction algorithm. This approach permits the CT rotation scanning of multiple objects simultaneously without the increase of penetration thickness and the signal crosstalk. Compared with the conventional single-mounted methods, it has the potential to improve the imaging efficiency and suppress the artifacts from the beam hardening and the scatter. This work comprises a numerical study of the method and its experimental verification using a dataset measured with a developed multi-mounted X-ray CT prototype system. We believe that this technique is of particular interest for pushing the engineering applications of X-ray CT. PMID:27073911

Lateral topography for reducing effective dose in low-dose chest CT.

PubMed

Bang, Dong-Ho; Lim, Daekeon; Hwang, Wi-Sub; Park, Seong-Hoon; Jeong, Ok-man; Kang, Kyung Wook; Kang, Hohyung

2013-06-01

The purposes of this study were to assess radiation exposure during low-dose chest CT by using lateral topography and to compare the lateral topographic findings with findings obtained with anteroposterior topography alone and anteroposterior and lateral topography combined. From November 2011 to February 2012, 210 male subjects were enrolled in the study. Age, weight, and height of the men were recorded. All subjects were placed into one of three subgroups based on the type of topographic image obtained: anteroposterior topography, lateral topography, and both anteroposterior and lateral topography. Imaging was performed with a 128-MDCT scanner. CT, except for topography, was the same for all subjects. A radiologist analyzed each image, recorded scan length, checked for any insufficiencies in the FOV, and calculated the effective radiation dose. One-way analysis of variance and multiple comparisons were used to compare the effective radiation exposure and scan length between groups. The mean scan length in the anteroposterior topography group was significantly greater than that of the lateral topography group and the combined anteroposterior and lateral topography group (p < 0.001). The mean effective radiation dose for the lateral topography group (0.735 ± 0.033 mSv) was significantly lower than that for the anteroposterior topography group (0.763 ± 0.038 mSv) and the combined anteroposterior and lateral topography group (0.773 ± 0.038) (p < 0.001). Lateral topographic low-dose CT was associated with a lower effective radiation dose and scan length than either anteroposterior topographic low-dose chest CT or low-dose chest CT with both anteroposterior and lateral topograms.

The accuracy of ultrashort echo time MRI sequences for medical additive manufacturing

PubMed Central

Rijkhorst, Erik-Jan; Hofman, Mark; Forouzanfar, Tymour; Wolff, Jan

2016-01-01

Objectives: Additively manufactured bone models, implants and drill guides are becoming increasingly popular amongst maxillofacial surgeons and dentists. To date, such constructs are commonly manufactured using CT technology that induces ionizing radiation. Recently, ultrashort echo time (UTE) MRI sequences have been developed that allow radiation-free imaging of facial bones. The aim of the present study was to assess the feasibility of UTE MRI sequences for medical additive manufacturing (AM). Methods: Three morphologically different dry human mandibles were scanned using a CT and MRI scanner. Additionally, optical scans of all three mandibles were made to acquire a “gold standard”. All CT and MRI scans were converted into Standard Tessellation Language (STL) models and geometrically compared with the gold standard. To quantify the accuracy of the AM process, the CT, MRI and gold-standard STL models of one of the mandibles were additively manufactured, optically scanned and compared with the original gold-standard STL model. Results: Geometric differences between all three CT-derived STL models and the gold standard were <1.0 mm. All three MRI-derived STL models generally presented deviations <1.5 mm in the symphyseal and mandibular area. The AM process introduced minor deviations of <0.5 mm. Conclusions: This study demonstrates that MRI using UTE sequences is a feasible alternative to CT in generating STL models of the mandible and would therefore be suitable for surgical planning and AM. Further in vivo studies are necessary to assess the usability of UTE MRI sequences in clinical settings. PMID:26943179

A navigation system for flexible endoscopes using abdominal 3D ultrasound

NASA Astrophysics Data System (ADS)

Hoffmann, R.; Kaar, M.; Bathia, Amon; Bathia, Amar; Lampret, A.; Birkfellner, W.; Hummel, J.; Figl, M.

2014-09-01

A navigation system for flexible endoscopes equipped with ultrasound (US) scan heads is presented. In contrast to similar systems, abdominal 3D-US is used for image fusion of the pre-interventional computed tomography (CT) to the endoscopic US. A 3D-US scan, tracked with an optical tracking system (OTS), is taken pre-operatively together with the CT scan. The CT is calibrated using the OTS, providing the transformation from CT to 3D-US. Immediately before intervention a 3D-US tracked with an electromagnetic tracking system (EMTS) is acquired and registered intra-modal to the preoperative 3D-US. The endoscopic US is calibrated using the EMTS and registered to the pre-operative CT by an intra-modal 3D-US/3D-US registration. Phantom studies showed a registration error for the US to CT registration of 5.1 mm ± 2.8 mm. 3D-US/3D-US registration of patient data gave an error of 4.1 mm compared to 2.8 mm with the phantom. From this we estimate an error on patient experiments of 5.6 mm.

Utility of CT-compatible EEG electrodes in critically ill children.

PubMed

Abend, Nicholas S; Dlugos, Dennis J; Zhu, Xiaowei; Schwartz, Erin S

2015-04-01

Electroencephalographic monitoring is being used with increasing frequency in critically ill children who may require frequent and sometimes urgent brain CT scans. Standard metallic disk EEG electrodes commonly produce substantial imaging artifact, and they must be removed and later reapplied when CT scans are indicated. To determine whether conductive plastic electrodes caused artifact that limited CT interpretation. We describe a retrospective cohort of 13 consecutive critically ill children who underwent 17 CT scans with conductive plastic electrodes during 1 year. CT images were evaluated by a pediatric neuroradiologist for artifact presence, type and severity. All CT scans had excellent quality images without artifact that impaired CT interpretation except for one scan in which improper wire placement resulted in artifact. Conductive plastic electrodes do not cause artifact limiting CT scan interpretation and may be used in critically ill children to permit concurrent electroencephalographic monitoring and CT imaging.

SU-G-IeP4-11: Monitoring Tumor Growth in Subcutaneous Murine Tumor Model in Vivo: A Comparison Between MRI and Small Animal CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, B; He, W; Cvetkovic, D

Purpose: The purpose of the study is to compare the volume measurement of subcutaneous tumors in mice with different imaging platforms, namely a GE MRI and a Sofie-Biosciences small animal CT scanner. Methods: A549 human lung carcinoma cells and FaDu human head and neck squamous cell carcinoma cells were implanted subcutaneously into flanks of nude mice. Three FaDu tumors and three A549 tumors were included in this study. The MRI scans were done with a GE Signa 1.5 Tesla MR scanner using a fast T2-weighted sequence (70mm FOV and 1.2mm slice thickness), while the CT scans were done with themore » CT scanner on a Sofie-Biosciences G8 PET/CT platform dedicated for small animal studies (48mm FOV and 0.2mm slice thickness). Imaging contrast agent was not used in this study. Based on the DICOM images from MRI and CT scans, the tumors were contoured with Philips DICOM Viewer and the tumor volumes were obtained by summing up the contoured area and multiplied by the slice thickness. Results: The volume measurements based on the CT scans agree reasonably with that obtained with MR images for the subcutaneous tumors. The mean difference in the absolute tumor volumes between MRI- and CT-based measurements was found to be −6.2% ± 1.0%, with the difference defined as (VMR – VCT)*100%/VMR. Furthermore, we evaluated the normalized tumor volumes, which were defined for each tumor as V/V{sub 0} where V{sub 0} stands for the volume from the first MR or CT scan. The mean difference in the normalized tumor volumes was found to be 0.10% ± 0.96%. Conclusion: Despite the fact that the difference between normal and abnormal tissues is often less clear on small animal CT images than on MR images, one can still obtain reasonable tumor volume information with the small animal CT scans for subcutaneous murine xenograft models.« less

TU-C-12A-11: Comparisons Between Cu-ATSM PET and DCE-CT Kinetic Parameters in Canine Sinonasal Tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

La Fontaine, M; Bradshaw, T; Kubicek, L

2014-06-15

Purpose: Regions of poor perfusion within tumors may be associated with higher hypoxic levels. This study aimed to test this hypothesis by comparing measurements of hypoxia from Cu-ATSM PET to vasculature kinetic parameters from DCE-CT kinetic analysis. Methods: Ten canine patients with sinonasal tumors received one Cu-ATSM PET/CT scan and three DCE-CT scans prior to treatment. Cu-ATSM PET/CT and DCE-CT scans were registered and resampled to matching voxel dimensions. Kinetic analysis was performed on DCE-CT scans and for each patient, the resulting kinetic parameter values from the three DCE-CT scans were averaged together. Cu-ATSM SUVs were spatially correlated (r{sub spatial})more » on a voxel-to-voxel basis against the following DCE-CT kinetic parameters: transit time (t{sub 1}), blood flow (F), vasculature fraction (v{sub 1}), and permeability (PS). In addition, whole-tumor comparisons were performed by correlating (r{sub ROI}) the mean Cu-ATSM SUV (SUV{sub mean}) with median kinetic parameter values. Results: The spatial correlations (r{sub spatial}) were poor and ranged from -0.04 to 0.21 for all kinetic parameters. These low spatial correlations may be due to high variability in the DCE-CT kinetic parameter voxel values between scans. In our hypothesis, t{sub 1} was expected to have a positive correlation, while F was expected to have a negative correlation to hypoxia. However, in wholetumor analysis the opposite was found for both t{sub 1} (r{sub ROI} = -0.25) and F (r{sub ROI} = 0.56). PS and v{sub 1} may depict angiogenic responses to hypoxia and found positive correlations to Cu-ATSM SUV for PS (r{sub ROI} = 0.41), and v{sub 1} (r{sub ROI} = 0.57). Conclusion: Low spatial correlations were found between Cu-ATSM uptake and DCE-CT vasculature parameters, implying that poor perfusion is not associated with higher hypoxic regions. Across patients, the most hypoxic tumors tended to have higher blood flow values, which is contrary to our initial hypothesis. Funding: R01 CA136927.« less

Relevance of early head CT scans following neurosurgical procedures: an analysis of 892 intracranial procedures at Rush University Medical Center.

PubMed

Fontes, Ricardo B V; Smith, Adam P; Muñoz, Lorenzo F; Byrne, Richard W; Traynelis, Vincent C

2014-08-01

Early postoperative head CT scanning is routinely performed following intracranial procedures for detection of complications, but its real value remains uncertain: so-called abnormal results are frequently found, but active, emergency intervention based on these findings may be rare. The authors' objective was to analyze whether early postoperative CT scans led to emergency surgical interventions and if the results of neurological examination predicted this occurrence. The authors retrospectively analyzed 892 intracranial procedures followed by an early postoperative CT scan performed over a 1-year period at Rush University Medical Center and classified these cases according to postoperative neurological status: baseline, predicted neurological change, unexpected neurological change, and sedated or comatose. The interpretation of CT results was reviewed and unexpected CT findings were classified based on immediate action taken: Type I, additional observation and CT; Type II, active nonsurgical intervention; and Type III, surgical intervention. Results were compared between neurological examination groups with the Fisher exact test. Patients with unexpected neurological changes or in the sedated or comatose group had significantly more unexpected findings on the postoperative CT (p < 0.001; OR 19.2 and 2.3, respectively) and Type II/III interventions (p < 0.001) than patients at baseline. Patients at baseline or with expected neurological changes still had a rate of Type II/III changes in the 2.2%-2.4% range; however, no patient required an immediate return to the operating room. Over a 1-year period in an academic neurosurgery service, no patient who was neurologically intact or who had a predicted neurological change required an immediate return to the operating room based on early postoperative CT findings. Obtaining early CT scans should not be a priority in these patients and may even be cancelled in favor of MRI studies, if the latter have already been planned and can be performed safely and in a timely manner. Early postoperative CT scanning does not assure an uneventful course, nor should it replace accurate and frequent neurological checks, because operative interventions were always decided in conjunction with the neurological examination.

Chromatic dispersive confocal technology for intra-oral scanning: first in-vitro results

NASA Astrophysics Data System (ADS)

Ertl, T.; Zint, M.; Konz, A.; Brauer, E.; Hörhold, H.; Hibst, R.

2015-02-01

Various test objects, plaster models, partially equipped with extracted teeth and pig jaws representing various clinical situations of tooth preparations were used for in-vitro scanning tests with an experimental intra-oral scanning system based on chromatic-dispersive confocal technology. Scanning results were compared against data sets of the same object captured by an industrial μCT measuring system. Compared to μCT data an average error of 18 - 30 μm was achieved for a single tooth scan area and less than 40 to 60 μm error measured over the restoration + the neighbor teeth and pontic areas up to 7 units. Mean error for a full jaw is within 100 - 140 μm. The length error for a 3 - 4 unit bridge situation form contact point to contact point is below 100 μm and excellent interproximal surface coverage and prep margin clarity was achieved.

Assessment of hemodynamics in a rat model of liver cirrhosis with precancerous lesions using multislice spiral CT perfusion imaging.

PubMed

Ma, Guolin; Bai, Rongjie; Jiang, Huijie; Hao, Xuejia; Ling, Zaisheng; Li, Kefeng

2013-01-01

To develop an optimal scanning protocol for multislice spiral CT perfusion (CTP) imaging to evaluate hemodynamic changes in liver cirrhosis with diethylnitrosamine- (DEN-) induced precancerous lesions. Male Wistar rats were randomly divided into the control group (n = 80) and the precancerous liver cirrhosis group (n = 40). The control group received saline injection and the liver cirrhosis group received 50 mg/kg DEN i.p. twice a week for 12 weeks. All animals underwent plain CT scanning, CTP, and contrast-enhanced CT scanning. Scanning parameters were optimized by adjusting the diatrizoate concentration, the flow rate, and the delivery time. The hemodynamics of both groups was further compared using optimized multislice spiral CTP imaging. High-quality CTP images were obtained with following parameters: 150 kV; 150 mAs; 5 mm thickness, 5 mm interval; pitch, 1; matrix, 512 × 512; and FOV, 9.6 cm. Compared to the control group, the liver cirrhosis group had a significantly increased value of the hepatic arterial fraction and the hepatic artery perfusion (P < 0.05) but significantly decreased hepatic portal perfusion and mean transit time (P < 0.05). Multislice spiral CTP imaging can be used to evaluate the hemodynamic changes in the rat model of liver cirrhosis with precancerous lesions.

Automated coronary artery calcification detection on low-dose chest CT images

NASA Astrophysics Data System (ADS)

Xie, Yiting; Cham, Matthew D.; Henschke, Claudia; Yankelevitz, David; Reeves, Anthony P.

2014-03-01

Coronary artery calcification (CAC) measurement from low-dose CT images can be used to assess the risk of coronary artery disease. A fully automatic algorithm to detect and measure CAC from low-dose non-contrast, non-ECG-gated chest CT scans is presented. Based on the automatically detected CAC, the Agatston score (AS), mass score and volume score were computed. These were compared with scores obtained manually from standard-dose ECG-gated scans and low-dose un-gated scans of the same patient. The automatic algorithm segments the heart region based on other pre-segmented organs to provide a coronary region mask. The mitral valve and aortic valve calcification is identified and excluded. All remaining voxels greater than 180HU within the mask region are considered as CAC candidates. The heart segmentation algorithm was evaluated on 400 non-contrast cases with both low-dose and regular dose CT scans. By visual inspection, 371 (92.8%) of the segmentations were acceptable. The automated CAC detection algorithm was evaluated on 41 low-dose non-contrast CT scans. Manual markings were performed on both low-dose and standard-dose scans for these cases. Using linear regression, the correlation of the automatic AS with the standard-dose manual scores was 0.86; with the low-dose manual scores the correlation was 0.91. Standard risk categories were also computed. The automated method risk category agreed with manual markings of gated scans for 24 cases while 15 cases were 1 category off. For low-dose scans, the automatic method agreed with 33 cases while 7 cases were 1 category off.

Lumbar spine CT scan

MedlinePlus

CAT scan - lumbar spine; Computed axial tomography scan - lumbar spine; Computed tomography scan - lumbar spine; CT - lower back ... CT scans rapidly makes detailed pictures of the lower back. The test may be used to look for: ...

Ionising radiation-free whole-body MRI versus (18)F-fluorodeoxyglucose PET/CT scans for children and young adults with cancer: a prospective, non-randomised, single-centre study.

PubMed

Klenk, Christopher; Gawande, Rakhee; Uslu, Lebriz; Khurana, Aman; Qiu, Deqiang; Quon, Andrew; Donig, Jessica; Rosenberg, Jarrett; Luna-Fineman, Sandra; Moseley, Michael; Daldrup-Link, Heike E

2014-03-01

Imaging tests are essential for staging of children with cancer. However, CT and radiotracer-based imaging procedures are associated with substantial exposure to ionising radiation and risk of secondary cancer development later in life. Our aim was to create a highly effective, clinically feasible, ionising radiation-free staging method based on whole-body diffusion-weighted MRI and the iron supplement ferumoxytol, used off-label as a contrast agent. We compared whole-body diffusion-weighted MRI with standard clinical (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT scans in children and young adults with malignant lymphomas and sarcomas. Whole-body diffusion-weighted magnetic resonance images were generated by coregistration of colour-encoded ferumoxytol-enhanced whole-body diffusion-weighted MRI scans for tumour detection with ferumoxytol-enhanced T1-weighted MRI scans for anatomical orientation, similar to the concept of integrated (18)F-FDG PET/CT scans. Tumour staging results were compared using Cohen's κ statistics. Histopathology and follow-up imaging served as the standard of reference. Data was assessed in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT01542879. 22 of 23 recruited patients were analysed because one patient discontinued before completion of the whole-body scan. Mean exposure to ionising radiation was 12·5 mSv (SD 4·1) for (18)F-FDG PET/CT compared with zero for whole-body diffusion-weighted MRI. (18)F-FDG PET/CT detected 163 of 174 malignant lesions at 1325 anatomical regions and whole-body diffusion-weighted MRI detected 158. Comparing (18)F-FDG PET/CT to whole-body diffusion-weighted MRI, sensitivities were 93·7% (95% CI 89·0-96·8) versus 90·8% (85·5-94·7); specificities 97·7% (95% CI 96·7-98·5) versus 99·5% (98·9-99·8); and diagnostic accuracies 97·2% (93·6-99·4) versus 98·3% (97·4-99·2). Tumour staging results showed very good agreement between both imaging modalities with a κ of 0·93 (0·81-1·00). No adverse events after administration of ferumoxytol were recorded. Ferumoxytol-enhanced whole-body diffusion-weighted MRI could be an alternative to (18)F-FDG PET/CT for staging of children and young adults with cancer that is free of ionising radiation. This new imaging test might help to prevent long-term side-effects from radiographic staging procedures. Thrasher Research Fund and Clinical Health Research Institute at Stanford University. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Role of Computed Tomography in Blunt Abdominal Trauma.

PubMed

Karki, O B

2015-01-01

Blunt injury trauma is regularly encountered in the emergency department. Diagnostic tools that help in optimum management of blunt abdominal trauma include; Focussed Assessment Sonography for Trauma scan, Diagnostic peritoneal lavage and Computed Tomography scan. The aim of this study is to determine the validity of CT scan as an accurate diagnostic tool and its role in management of patients with blunt abdominal trauma. A prospective analysis of 80 patients of blunt abdomen trauma who were admitted in Manipal Teaching Hospital, Pokhara, Nepal within a span of 15 months was done. Demographic data, mechanism of trauma, management and outcomes were studied. Organ injuries were graded using the Organ Injury Scale guidelines. Most of the patients in our study were in the age group of 21-40 years with an M: F ratio of 2.3:1. Road traffic accident (47.5%) was the most common mechanism of injury. Spleen (27.5%) was the commonest organ injured. CT scan was superior to FAST scan and had sensitivity of 97.3% specificity 75% positive predictive value 98.6%. FAST scan had sensitivity of 78.9%, specificity 50%, positive predictive value 96% with p- value of 0.0034. 81% of patients were conservatively managed. In conjunction with close clinical monitoring, CT scan is reliable in the evaluation and management of blunt abdominal trauma patients. Our study also shows CT as a superior diagnostic modality compared to FAST scan.

Limitations of Airway Dimension Measurement on Images Obtained Using Multi-Detector Row Computed Tomography

PubMed Central

Oguma, Tsuyoshi; Hirai, Toyohiro; Niimi, Akio; Matsumoto, Hisako; Muro, Shigeo; Shigematsu, Michio; Nishimura, Takashi; Kubo, Yoshiro; Mishima, Michiaki

2013-01-01

Objectives (a) To assess the effects of computed tomography (CT) scanners, scanning conditions, airway size, and phantom composition on airway dimension measurement and (b) to investigate the limitations of accurate quantitative assessment of small airways using CT images. Methods An airway phantom, which was constructed using various types of material and with various tube sizes, was scanned using four CT scanner types under different conditions to calculate airway dimensions, luminal area (Ai), and the wall area percentage (WA%). To investigate the limitations of accurate airway dimension measurement, we then developed a second airway phantom with a thinner tube wall, and compared the clinical CT images of healthy subjects with the phantom images scanned using the same CT scanner. The study using clinical CT images was approved by the local ethics committee, and written informed consent was obtained from all subjects. Data were statistically analyzed using one-way ANOVA. Results Errors noted in airway dimension measurement were greater in the tube of small inner radius made of material with a high CT density and on images reconstructed by body algorithm (p<0.001), and there was some variation in error among CT scanners under different fields of view. Airway wall thickness had the maximum effect on the accuracy of measurements with all CT scanners under all scanning conditions, and the magnitude of errors for WA% and Ai varied depending on wall thickness when airways of <1.0-mm wall thickness were measured. Conclusions The parameters of airway dimensions measured were affected by airway size, reconstruction algorithm, composition of the airway phantom, and CT scanner types. In dimension measurement of small airways with wall thickness of <1.0 mm, the accuracy of measurement according to quantitative CT parameters can decrease as the walls become thinner. PMID:24116105

Effects of Iterative Reconstruction Algorithms on Computer-assisted Detection (CAD) Software for Lung Nodules in Ultra-low-dose CT for Lung Cancer Screening.

PubMed

Nomura, Yukihiro; Higaki, Toru; Fujita, Masayo; Miki, Soichiro; Awaya, Yoshikazu; Nakanishi, Toshio; Yoshikawa, Takeharu; Hayashi, Naoto; Awai, Kazuo

2017-02-01

This study aimed to evaluate the effects of iterative reconstruction (IR) algorithms on computer-assisted detection (CAD) software for lung nodules in ultra-low-dose computed tomography (ULD-CT) for lung cancer screening. We selected 85 subjects who underwent both a low-dose CT (LD-CT) scan and an additional ULD-CT scan in our lung cancer screening program for high-risk populations. The LD-CT scans were reconstructed with filtered back projection (FBP; LD-FBP). The ULD-CT scans were reconstructed with FBP (ULD-FBP), adaptive iterative dose reduction 3D (AIDR 3D; ULD-AIDR 3D), and forward projected model-based IR solution (FIRST; ULD-FIRST). CAD software for lung nodules was applied to each image dataset, and the performance of the CAD software was compared among the different IR algorithms. The mean volume CT dose indexes were 3.02 mGy (LD-CT) and 0.30 mGy (ULD-CT). For overall nodules, the sensitivities of CAD software at 3.0 false positives per case were 78.7% (LD-FBP), 9.3% (ULD-FBP), 69.4% (ULD-AIDR 3D), and 77.8% (ULD-FIRST). Statistical analysis showed that the sensitivities of ULD-AIDR 3D and ULD-FIRST were significantly higher than that of ULD-FBP (P < .001). The performance of CAD software in ULD-CT was improved by using IR algorithms. In particular, the performance of CAD in ULD-FIRST was almost equivalent to that in LD-FBP. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Content Validity of Temporal Bone Models Printed Via Inexpensive Methods and Materials.

PubMed

Bone, T Michael; Mowry, Sarah E

2016-09-01

Computed tomographic (CT) scans of the 3-D printed temporal bone models will be within 15% accuracy of the CT scans of the cadaveric temporal bones. Previous studies have evaluated the face validity of 3-D-printed temporal bone models designed to train otolaryngology residents. The purpose of the study was to determine the content validity of temporal bone models printed using inexpensive printers and materials. Four cadaveric temporal bones were randomly selected and clinical temporal bone CT scans were obtained. Models were generated using previously described methods in acrylonitrile butadiene styrene (ABS) plastic using the Makerbot Replicator 2× and Hyrel printers. Models were radiographically scanned using the same protocol as the cadaveric bones. Four images from each cadaveric CT series and four corresponding images from the model CT series were selected, and voxel values were normalized to black or white. Scan slices were compared using PixelDiff software. Gross anatomic structures were evaluated in the model scans by four board certified otolaryngologists on a 4-point scale. Mean pixel difference between the cadaver and model scans was 14.25 ± 2.30% at the four selected CT slices. Mean cortical bone width difference and mean external auditory canal width difference were 0.58 ± 0.66 mm and 0.55 ± 0.46 mm, respectively. Expert raters felt the mastoid air cells were well represented (2.5 ± 0.5), while middle ear and otic capsule structures were not accurately rendered (all averaged <1.8). These results suggest that these models would be sufficient adjuncts to cadaver temporal bones for training residents in cortical mastoidectomies, but less effective for middle ear procedures.

Combined endeavor of Neutrosophic Set and Chan-Vese model to extract accurate liver image from CT scan.

PubMed

Siri, Sangeeta K; Latte, Mrityunjaya V

2017-11-01

Many different diseases can occur in the liver, including infections such as hepatitis, cirrhosis, cancer and over effect of medication or toxins. The foremost stage for computer-aided diagnosis of liver is the identification of liver region. Liver segmentation algorithms extract liver image from scan images which helps in virtual surgery simulation, speedup the diagnosis, accurate investigation and surgery planning. The existing liver segmentation algorithms try to extort exact liver image from abdominal Computed Tomography (CT) scan images. It is an open problem because of ambiguous boundaries, large variation in intensity distribution, variability of liver geometry from patient to patient and presence of noise. A novel approach is proposed to meet challenges in extracting the exact liver image from abdominal CT scan images. The proposed approach consists of three phases: (1) Pre-processing (2) CT scan image transformation to Neutrosophic Set (NS) and (3) Post-processing. In pre-processing, the noise is removed by median filter. The "new structure" is designed to transform a CT scan image into neutrosophic domain which is expressed using three membership subset: True subset (T), False subset (F) and Indeterminacy subset (I). This transform approximately extracts the liver image structure. In post processing phase, morphological operation is performed on indeterminacy subset (I) and apply Chan-Vese (C-V) model with detection of initial contour within liver without user intervention. This resulted in liver boundary identification with high accuracy. Experiments show that, the proposed method is effective, robust and comparable with existing algorithm for liver segmentation of CT scan images. Copyright © 2017 Elsevier B.V. All rights reserved.

CT texture features of liver parenchyma for predicting development of metastatic disease and overall survival in patients with colorectal cancer.

PubMed

Lee, Scott J; Zea, Ryan; Kim, David H; Lubner, Meghan G; Deming, Dustin A; Pickhardt, Perry J

2018-04-01

To determine if identifiable hepatic textural features are present at abdominal CT in patients with colorectal cancer (CRC) prior to the development of CT-detectable hepatic metastases. Four filtration-histogram texture features (standard deviation, skewness, entropy and kurtosis) were extracted from the liver parenchyma on portal venous phase CT images at staging and post-treatment surveillance. Surveillance scans corresponded to the last scan prior to the development of CT-detectable CRC liver metastases in 29 patients (median time interval, 6 months), and these were compared with interval-matched surveillance scans in 60 CRC patients who did not develop liver metastases. Predictive models of liver metastasis-free survival and overall survival were built using regularised Cox proportional hazards regression. Texture features did not significantly differ between cases and controls. For Cox models using all features as predictors, all coefficients were shrunk to zero, suggesting no association between any CT texture features and outcomes. Prognostic indices derived from entropy features at surveillance CT incorrectly classified patients into risk groups for future liver metastases (p < 0.001). On surveillance CT scans immediately prior to the development of CRC liver metastases, we found no evidence suggesting that changes in identifiable hepatic texture features were predictive of their development. • No correlation between liver texture features and metastasis-free survival was observed. • Liver texture features incorrectly classified patients into risk groups for liver metastases. • Standardised texture analysis workflows need to be developed to improve research reproducibility.

11C-Methionine Positron Emission Tomography/Computed Tomography Versus 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Evaluation of Residual or Recurrent World Health Organization Grades II and III Meningioma After Treatment.

PubMed

Tomura, Noriaki; Saginoya, Toshiyuki; Goto, Hiromi

2018-04-02

The aim of this study was to determine the assessment of positron emission tomography-computed tomography using C-methionine (MET PET/CT) for World Health Organization (WHO) grades II and III meningiomas; MET PET/CT was compared with PET/CT using F-fluorodeoxy glucose (FDG PET/CT). This study was performed in 17 cases with residual and/or recurrent WHO grades II and III meningiomas. Two neuroradiologists reviewed both PET/CT scans. For agreement, the κ coefficient was measured. Difference in tumor-to-normal brain uptake ratios (T/N ratios) between 2 PET/CT scans was analyzed. Correlation between the maximum tumor size and T/N ratio in PET/CT was studied. For agreement by both reviewers, the κ coefficient was 0.51 (P < 0.05). The T/N ratio was significantly higher for MET PET/CT (3.24 ± 1.36) than for FDG PET/CT (0.93 ± 0.44) (P < 0.01). C-methionine ratio significantly correlated with tumor size (y = 8.1x + 16.3, n = 22, P < 0.05), but FDG ratio did not CONCLUSIONS: C-methionine PET/CT has superior potential for imaging of WHO grades II and III meningiomas with residual or recurrent tumors compared with FDG PET/CT.

Improving Spleen Volume Estimation via Computer Assisted Segmentation on Clinically Acquired CT Scans

PubMed Central

Xu, Zhoubing; Gertz, Adam L.; Burke, Ryan P.; Bansal, Neil; Kang, Hakmook; Landman, Bennett A.; Abramson, Richard G.

2016-01-01

OBJECTIVES Multi-atlas fusion is a promising approach for computer-assisted segmentation of anatomical structures. The purpose of this study was to evaluate the accuracy and time efficiency of multi-atlas segmentation for estimating spleen volumes on clinically-acquired CT scans. MATERIALS AND METHODS Under IRB approval, we obtained 294 deidentified (HIPAA-compliant) abdominal CT scans on 78 subjects from a recent clinical trial. We compared five pipelines for obtaining splenic volumes: Pipeline 1–manual segmentation of all scans, Pipeline 2–automated segmentation of all scans, Pipeline 3–automated segmentation of all scans with manual segmentation for outliers on a rudimentary visual quality check, Pipelines 4 and 5–volumes derived from a unidimensional measurement of craniocaudal spleen length and three-dimensional splenic index measurements, respectively. Using Pipeline 1 results as ground truth, the accuracy of Pipelines 2–5 (Dice similarity coefficient [DSC], Pearson correlation, R-squared, and percent and absolute deviation of volume from ground truth) were compared for point estimates of splenic volume and for change in splenic volume over time. Time cost was also compared for Pipelines 1–5. RESULTS Pipeline 3 was dominant in terms of both accuracy and time cost. With a Pearson correlation coefficient of 0.99, average absolute volume deviation 23.7 cm3, and 1 minute per scan, Pipeline 3 yielded the best results. The second-best approach was Pipeline 5, with a Pearson correlation coefficient 0.98, absolute deviation 46.92 cm3, and 1 minute 30 seconds per scan. Manual segmentation (Pipeline 1) required 11 minutes per scan. CONCLUSION A computer-automated segmentation approach with manual correction of outliers generated accurate splenic volumes with reasonable time efficiency. PMID:27519156

Use of gadoxetic acid for computed tomographic cholangiography in healthy dogs.

PubMed

Chau, Jennifer; Podadera, Juan M; Young, Alex C; Makara, Mariano A

2017-07-01

OBJECTIVE To evaluate the effect of gadoxetic acid (contrast) dose on biliary tract enhancement, determine the optimal time after contrast injection for CT image acquisition, and assess the feasibility of CT cholangiography in sedated dogs. ANIMALS 8 healthy dogs. PROCEDURES The study had 2 parts. In part 1, 4 dogs were anesthetized and underwent CT cholangiography twice. Gadoxetic acid was administered IV at a low dose (0.025 mmol/kg) for the first procedure and high dose (0.3 mmol/kg) for the second procedure. Serial CT scans were obtained at predetermined times after contrast injection. In part 2, 4 dogs were sedated and underwent CT angiography 85 minutes after IV administration of the high contrast dose. Contrast enhancement of the biliary tract on all scans was objectively assessed by measurement of CT attenuation and qualitatively assessed by use of a subjective 4-point scoring system by 3 independent reviewers. All measurements were compared over time and between contrast doses for the dogs of part 1. Subjective measurements were compared between the sedated dogs of part 2 and anesthetized dogs of part 1. RESULTS Enhancement of the biliary tract was positively associated with contrast dose and time after contrast injection. Optimal enhancement was achieved 65 minutes after contrast injection. Subjective visualization of most biliary structures did not differ significantly between sedated and anesthetized dogs. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated CT cholangiography with gadoxetic acid was feasible in sedated dogs. The high contrast dose provided better visualization of biliary structures than the low dose; CT scans should be obtained 65 minutes after contrast injection.

Does diagnosis change as a result of repeat renal colic computed tomography scan in patients with a history of kidney stones?

PubMed

Goldstone, Adam; Bushnell, Andrew

2010-03-01

We sought to determine the incidence of alternative diagnosis in patients with a history of kidney stones who experience recurrent symptoms and undergo repeat computed tomography (CT) imaging at their return to the emergency department (ED). This was a retrospective chart review of ED patients at a tertiary care hospital. Inclusion criteria were all adult ED patients who received a repeat CT for renal colic, after having previously received the diagnosis of obstructive kidney stone confirmed by CT, in our ED. Patients were identified by reviewing the charts of those patients with repeat visits to the ED after January 1, 2004, in which they complained of symptoms suggestive of renal colic and received a CT scan. We determined the frequency of the same diagnosis on repeat CT scan in this population compared with the frequency of alternative diagnosis. Two hundred thirty-one patients met criteria for the study. Fifty-nine percent were male. One hundred eighty-nine (81.8%) patients had no change in diagnosis as a result of a repeat renal colic CT scan. Twenty-seven (11.6%) patients received an alternative diagnosis that did not require urgent intervention, and 15 (6.5%) patients received a diagnosis that did require an urgent intervention. Repeat CT imaging of patients with known nephrolithiasis changed management in a minority of patients (6.5%). Knowing the frequency of alternative diagnosis in this population may help clinicians and patients balance the risks and benefits of repeat renal colic CT scans in patients with a history of kidney stones who return to the ED with similar symptoms. 2010 Elsevier Inc. All rights reserved.

Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians

PubMed Central

Forsythe, Anna V; Brady, Zoe; Butler, Martin W; Goergen, Stacy K; Byrnes, Graham B; Giles, Graham G; Wallace, Anthony B; Anderson, Philip R; Guiver, Tenniel A; McGale, Paul; Cain, Timothy M; Dowty, James G; Bickerstaffe, Adrian C; Darby, Sarah C

2013-01-01

Objective To assess the cancer risk in children and adolescents following exposure to low dose ionising radiation from diagnostic computed tomography (CT) scans. Design Population based, cohort, data linkage study in Australia. Cohort members 10.9 million people identified from Australian Medicare records, aged 0-19 years on 1 January 1985 or born between 1 January 1985 and 31 December 2005; all exposures to CT scans funded by Medicare during 1985-2005 were identified for this cohort. Cancers diagnosed in cohort members up to 31 December 2007 were obtained through linkage to national cancer records. Main outcome Cancer incidence rates in individuals exposed to a CT scan more than one year before any cancer diagnosis, compared with cancer incidence rates in unexposed individuals. Results 60 674 cancers were recorded, including 3150 in 680 211 people exposed to a CT scan at least one year before any cancer diagnosis. The mean duration of follow-up after exposure was 9.5 years. Overall cancer incidence was 24% greater for exposed than for unexposed people, after accounting for age, sex, and year of birth (incidence rate ratio (IRR) 1.24 (95% confidence interval 1.20 to 1.29); P<0.001). We saw a dose-response relation, and the IRR increased by 0.16 (0.13 to 0.19) for each additional CT scan. The IRR was greater after exposure at younger ages (P<0.001 for trend). At 1-4, 5-9, 10-14, and 15 or more years since first exposure, IRRs were 1.35 (1.25 to 1.45), 1.25 (1.17 to 1.34), 1.14 (1.06 to 1.22), and 1.24 (1.14 to 1.34), respectively. The IRR increased significantly for many types of solid cancer (digestive organs, melanoma, soft tissue, female genital, urinary tract, brain, and thyroid); leukaemia, myelodysplasia, and some other lymphoid cancers. There was an excess of 608 cancers in people exposed to CT scans (147 brain, 356 other solid, 48 leukaemia or myelodysplasia, and 57 other lymphoid). The absolute excess incidence rate for all cancers combined was 9.38 per 100 000 person years at risk, as of 31 December 2007. The average effective radiation dose per scan was estimated as 4.5 mSv. Conclusions The increased incidence of cancer after CT scan exposure in this cohort was mostly due to irradiation. Because the cancer excess was still continuing at the end of follow-up, the eventual lifetime risk from CT scans cannot yet be determined. Radiation doses from contemporary CT scans are likely to be lower than those in 1985-2005, but some increase in cancer risk is still likely from current scans. Future CT scans should be limited to situations where there is a definite clinical indication, with every scan optimised to provide a diagnostic CT image at the lowest possible radiation dose. PMID:23694687

Ultra low-dose CT attenuation correction in PET SPM

NASA Astrophysics Data System (ADS)

Wang, Shyh-Jen; Yang, Bang-Hung; Tsai, Chia-Jung; Yang, Ching-Ching; Lee, Jason J. S.; Wu, Tung-Hsin

2010-07-01

The use of CT images for attenuation correction (CTAC) allows significantly shorter scanning time and a high quality noise-free attenuation map compared with conventional germanium-68 transmission scan because at least 10 4 times greater of photon flux would be generated from a CT scan under standard operating condition. However, this CTAC technique would potentially introduce more radiation risk to the patients owing to the higher radiation exposure from CT scan. Statistic parameters mapping (SPM) is a prominent technique in nuclear medicine community for the analysis of brain imaging data. The purpose of this study is to assess the feasibility of low-dose CT (LDCT) and ultra low-dose CT (UDCT) in PET SPM applications. The study was divided into two parts. The first part was to evaluate of tracer uptake distribution pattern and quantity analysis by using the striatal phantom to initially assess the feasibility of AC for clinical purpose. The second part was to examine the group SPM analysis using the Hoffman brain phantom. The phantom study is to simulate the human brain and to reduce the experimental uncertainty of real subjects. The initial studies show that the results of PET SPM analysis have no significant differences between LDCT and UDCT comparing to the current used default CTAC. Moreover, the dose of the LDCT is lower than that of the default CT by a factor of 9, and UDCT can even yield a 42 times dose reduction. We have demonstrated the SPM results while using LDCT and UDCT for PET AC is comparable to those using default CT setting, suggesting their feasibility in PET SPM applications. In addition, the necessity of UDCT in PET SPM studies to avoid excess radiation dose is also evident since most of the subjects involved are non-cancer patients or children and some normal subjects are even served as a comparison group in the experiment. It is our belief that additional attempts to decrease the radiation dose would be valuable, especially for children and normal volunteers, to work towards ALARA (as low as reasonably achievable) concept for PET SPM studies.

Quality of pediatric abdominal CT scans performed at a dedicated children's hospital and its referring institutions: a multifactorial evaluation.

PubMed

Snow, Aisling; Milliren, Carly E; Graham, Dionne A; Callahan, Michael J; MacDougall, Robert D; Robertson, Richard L; Taylor, George A

2017-04-01

Pediatric patients requiring transfer to a dedicated children's hospital from an outside institution may undergo CT imaging as part of their evaluation. Whether this imaging is performed prior to or after transfer has been shown to impact the radiation dose imparted to the patient. Other quality variables could also be affected by the pediatric experience and expertise of the scanning institution. To identify differences in quality between abdominal CT scans and reports performed at a dedicated children's hospital, and those performed at referring institutions. Fifty consecutive pediatric abdominal CT scans performed at outside institutions were matched (for age, gender and indication) with 50 CT scans performed at a dedicated freestanding children's hospital. We analyzed the scans for technical parameters, report findings, correlation with final clinical diagnosis, and clinical utility. Technical evaluation included use of intravenous and oral contrast agents, anatomical coverage, number of scan phases and size-specific dose estimate (SSDE) for each scan. Outside institution scans were re-reported when the child was admitted to the children's hospital; they were also re-interpreted for this study by children's hospital radiologists who were provided with only the referral information given in the outside institution's report. Anonymized original outside institutional reports and children's hospital admission re-reports were analyzed by two emergency medicine physicians for ease of understanding, degree to which the clinical question was answered, and level of confidence in the report. Mean SSDE was lower (8.68) for children's hospital scans, as compared to outside institution scans (13.29, P = 0.03). Concordance with final clinical diagnosis was significantly lower for original outside institution reports (38/48, 79%) than for both the admission and study children's hospital reports (48/50, 96%; P = 0.005). Children's hospital admission reports were rated higher than outside institution reports for completeness, ease of understanding, answering of clinical question, and level of confidence of the report (P < 0.001). Pediatric abdominal CT scans performed and interpreted at a dedicated children's hospital are associated with higher technical quality, lower radiation dose and a more clinically useful report than those performed at referring institutions.

WE-EF-207-07: Dual Energy CT with One Full Scan and a Second Sparse-View Scan Using Structure Preserving Iterative Reconstruction (SPIR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, T; Zhu, L

Purpose: Conventional dual energy CT (DECT) reconstructs CT and basis material images from two full-size projection datasets with different energy spectra. To relax the data requirement, we propose an iterative DECT reconstruction algorithm using one full scan and a second sparse-view scan by utilizing redundant structural information of the same object acquired at two different energies. Methods: We first reconstruct a full-scan CT image using filtered-backprojection (FBP) algorithm. The material similarities of each pixel with other pixels are calculated by an exponential function about pixel value differences. We assume that the material similarities of pixels remains in the second CTmore » scan, although pixel values may vary. An iterative method is designed to reconstruct the second CT image from reduced projections. Under the data fidelity constraint, the algorithm minimizes the L2 norm of the difference between pixel value and its estimation, which is the average of other pixel values weighted by their similarities. The proposed algorithm, referred to as structure preserving iterative reconstruction (SPIR), is evaluated on physical phantoms. Results: On the Catphan600 phantom, SPIR-based DECT method with a second 10-view scan reduces the noise standard deviation of a full-scan FBP CT reconstruction by a factor of 4 with well-maintained spatial resolution, while iterative reconstruction using total-variation regularization (TVR) degrades the spatial resolution at the same noise level. The proposed method achieves less than 1% measurement difference on electron density map compared with the conventional two-full-scan DECT. On an anthropomorphic pediatric phantom, our method successfully reconstructs the complicated vertebra structures and decomposes bone and soft tissue. Conclusion: We develop an effective method to reduce the number of views and therefore data acquisition in DECT. We show that SPIR-based DECT using one full scan and a second 10-view scan can provide high-quality DECT images and accurate electron density maps as conventional two-full-scan DECT.« less

Computed tomography use among children presenting to emergency departments with abdominal pain.

PubMed

Fahimi, Jahan; Herring, Andrew; Harries, Aaron; Gonzales, Ralph; Alter, Harrison

2012-11-01

To evaluate trends in and factors associated with computed tomography (CT) use among children presenting to the emergency department (ED) with abdominal pain. This study was a cross-sectional, secondary analysis of the National Hospital Ambulatory Medical Care Survey data from 1998 to 2008. We identified ED patients aged <19 years with abdominal pain and collected patient demographic and hospital characteristics, and outcomes related to imaging, hospital admission, and diagnosis of appendicitis. Trend analysis was performed over the study period for the outcomes of interest, and a multivariate regression model was used to identify factors associated with CT use. Of all pediatric ED visits, 6.0% were for abdominal pain. We noted a rise in the proportion of these patients with CT use, from 0.9% in 1998 to 15.4% in 2008 (P < .001), with no change in ultrasound/radiograph use, diagnosis of appendicitis, or hospital admission. Older and male patients were more likely to have a CT scan, whereas black children were one-half as likely to undergo a CT scan compared with white children (odds ratio: 0.50 [95% confidence interval: 0.31-0.81]). Admitted children had much higher odds of undergoing a CT scan (odds ratio: 4.11 [95% confidence interval: 2.66-6.35]). There was a plateau in CT use in 2006 to 2008. There was a dramatic increase in the utilization of CT imaging in the ED evaluation of pediatric patients with abdominal pain. Some groups of children may have a differential likelihood of receiving CT scans.

Performance evaluation of 2D and 3D deep learning approaches for automatic segmentation of multiple organs on CT images

NASA Astrophysics Data System (ADS)

Zhou, Xiangrong; Yamada, Kazuma; Kojima, Takuya; Takayama, Ryosuke; Wang, Song; Zhou, Xinxin; Hara, Takeshi; Fujita, Hiroshi

2018-02-01

The purpose of this study is to evaluate and compare the performance of modern deep learning techniques for automatically recognizing and segmenting multiple organ regions on 3D CT images. CT image segmentation is one of the important task in medical image analysis and is still very challenging. Deep learning approaches have demonstrated the capability of scene recognition and semantic segmentation on nature images and have been used to address segmentation problems of medical images. Although several works showed promising results of CT image segmentation by using deep learning approaches, there is no comprehensive evaluation of segmentation performance of the deep learning on segmenting multiple organs on different portions of CT scans. In this paper, we evaluated and compared the segmentation performance of two different deep learning approaches that used 2D- and 3D deep convolutional neural networks (CNN) without- and with a pre-processing step. A conventional approach that presents the state-of-the-art performance of CT image segmentation without deep learning was also used for comparison. A dataset that includes 240 CT images scanned on different portions of human bodies was used for performance evaluation. The maximum number of 17 types of organ regions in each CT scan were segmented automatically and compared to the human annotations by using ratio of intersection over union (IU) as the criterion. The experimental results demonstrated the IUs of the segmentation results had a mean value of 79% and 67% by averaging 17 types of organs that segmented by a 3D- and 2D deep CNN, respectively. All the results of the deep learning approaches showed a better accuracy and robustness than the conventional segmentation method that used probabilistic atlas and graph-cut methods. The effectiveness and the usefulness of deep learning approaches were demonstrated for solving multiple organs segmentation problem on 3D CT images.

TH-EF-BRA-04: Individually Optimized Contrast-Enhanced 4D-CT for Radiotherapy Simulation in Pancreatic Ductal Adenocarcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, W; Xue, M; Lane, B

Purpose: To develop an individually optimized contrast-enhanced (CE) 4D-CT for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). Methods: Ten PDA patients were enrolled. Each underwent 3 CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT using test injection. Three physicians contoured the tumor and pancreatic tissues. We compared image quality scores, tumor volume, motion, tumor-to-pancreas contrast, and contrast-to-noise ratio (CNR) in the 3 CTs. We also evaluated interobserver variations in contouring the tumor using simultaneous truth and performance level estimation (STAPLE). Results: Average image quality scores for CE 3DCT and CE 4D-CT were comparablemore » (4.0 and 3.8, respectively; P=0.47), and both were significantly better than that for 4D-CT (2.6, P<0.001). Tumor-to-pancreas contrast results were comparable in CE 3D-CT and CE 4D-CT (15.5 and 16.7 HU, respectively; P=0.71), and the latter was significantly higher than in 4D-CT (9.2 HU, P=0.03). Image noise in CE 3D-CT (12.5 HU) was significantly lower than in CE 4D-CT (22.1 HU, P<0.001) and 4D-CT (19.4 HU, P=0.005). CNRs were comparable in CE 3D-CT and CE 4DCT (1.4 and 0.8, respectively; P=0.23), and the former was significantly better than in 4D-CT (0.6, P = 0.04). Mean tumor volumes were smaller in CE 3D-CT (29.8 cm{sup 3}) and CE 4D-CT (22.8 cm{sup 3}) than in 4D-CT (42.0 cm{sup 3}), although these differences were not statistically significant. Mean tumor motion was comparable in 4D-CT and CE 4D-CT (7.2 and 6.2 mm, P=0.23). Interobserver variations were comparable in CE 3D-CT and CE 4D-CT (Jaccard index 66.0% and 61.9%, respectively) and were worse for 4D-CT (55.6%) than CE 3D-CT. Conclusion: CE 4D-CT demonstrated characteristics comparable to CE 3D-CT, with high potential for simultaneously delineating the tumor and quantifying tumor motion with a single scan. Supported in part by Philips Healthcare.« less

Comparison of distribution of lung aeration measured with EIT and CT in spontaneously breathing, awake patients1.

PubMed

Radke, Oliver C; Schneider, Thomas; Braune, Anja; Pirracchio, Romain; Fischer, Felix; Koch, Thea

2016-09-28

Both Electrical Impedance Tomography (EIT) and Computed Tomography (CT) allow the estimation of the lung area. We compared two algorithms for the detection of the lung area per quadrant from the EIT images with the lung areas derived from the CT images. 39 outpatients who were scheduled for an elective CT scan of the thorax were included in the study. For each patient we recorded EIT images immediately before the CT scan. The lung area per quadrant was estimated from both CT and EIT data using two different algorithms for the EIT data. Data showed considerable variation during spontaneous breathing of the patients. Overall correlation between EIT and CT was poor (0.58-0.77), the correlation between the two EIT algorithms was better (0.90-0.92). Bland-Altmann analysis revealed absence of bias, but wide limits of agreement. Lung area estimation from CT and EIT differs significantly, most probably because of the fundamental difference in image generation.

Lung Ultrasonography: A Viable Alternative to Chest Radiography in Children with Suspected Pneumonia?

PubMed

Ambroggio, Lilliam; Sucharew, Heidi; Rattan, Mantosh S; O'Hara, Sara M; Babcock, Diane S; Clohessy, Caitlin; Steinhoff, Mark C; Macaluso, Maurizio; Shah, Samir S; Coley, Brian D

2016-09-01

To determine the interrater reliability (IRR) of lung ultrasonography (LUS) and chest radiography (CXR) and evaluate the accuracy of LUS compared with CXR for detecting pediatric pneumonia compared with chest computed tomography (CT) scan. This was a prospective cohort study of children aged 3 months to 18 years with a CXR and LUS performed between May 1, 2012, and January 31, 2014 with or without a clinical diagnosis of pneumonia. Four pediatric radiologists blinded to clinical information reported findings for the CXR and LUS images. IRR was estimated for 50 LUS and CXR images. The main outcome was the finding from CT ordered clinically or the probability of the CT finding for patients clinically requiring CT. Two radiologists reviewed CT scans to determine an overall finding. Latent class analysis was used to evaluate the sensitivity and specificity for findings (eg, consolidation) for LUS and CXR compared with CT. Of the 132 patients in the cohort, 36 (27%) had CT performed for a clinical reason. Pneumonia was clinically documented in 47 patients (36%). The IRR for lung consolidation was 0.55 (95% CI, 0.40-0.70) for LUS and 0.36 (95% CI, 0.21-0.51) for CXR. The sensitivity for detecting consolidation, interstitial disease, and pleural effusion was statistically similar for LUS and CXR compared with CT; however, specificity was higher for CXR. The negative predictive value was similar for CXR and LUS. LUS has a sufficiently high IRR for detection of consolidation. Compared with CT, LUS and CXR have similar sensitivity, but CXR is more specific for findings indicating pneumonia. Copyright © 2016 Elsevier Inc. All rights reserved.

Diagnostic Performance of 11C-choline PET/CT and FDG PET/CT in Prostate Cancer.

PubMed

Kitajima, Kazuhiro; Yamamoto, Shingo; Odawara, Soichi; Kobayashi, Kaoru; Fujiwara, Masayuki; Kamikonya, Norihiko; Fukushima, Kazuhito; Nakanishi, Yukako; Hashimoto, Takahiko; Yamada, Yusuke; Suzuki, Toru; Kanematsu, Akihiro; Nojima, Michio; Yamakado, Koichiro

2018-06-01

We compared 11C-choline and FDG PET/CT scan findings for the staging and restaging of prostate cancer. Twenty Japanese prostate cancer patients underwent 11C-choline and FDG PET/CT before (n=5) or after (n=15) treatment. Using a five-point scale, we compared these scanning modalities regarding patient- and lesion-based diagnostic performance for local recurrence, untreated primary tumor, and lymph node and bony metastases. Of the 20 patients, documented local lesions, and node and bony metastases were present in 11 (55.0%), 9 (45.0%), and 13 (65.0%), respectively. The patient-based sensitivity/specificity/accuracy/area under the receiver-operating-characteristic curve (AUC) values for 11C-choline-PET/CT for diagnosing local lesions were 90.9% /100%/ 95.0% / 1.0, whereas those for FDG-PET/CT were 45.5% /100%/ 75.0% / 0.773. Those for 11C-choline-PET/CT for node metastasis were 88.9% /100%/ 95.0% / 0.944, and those for FDG-PET/CT were 44.4%/100%/75.0%/0.722. Those for 11C-choline-PET/CT for bone metastasis were 84.6%/100%/90.0%/0.951, and those for FDG-PET/CT were 76.9% /100%/ 85.0% / 0.962. The AUCs for local lesion and node metastasis differed significantly (p=0.0039, p=0.011, respectively). The lesion-based detection rates of 11C-choline compared to FDG PET/CT for local lesion, and node and bone metastases were 91.7% vs. 41.7%, 92.0% vs. 32.0%, and 94.8% vs. 83.0% (p=0.041, p=0.0030, p<0.0001), respectively. 11C-choline-PET/CT is more useful for the staging and restaging of prostate cancer than FDG-PET/CT in Japanese men.

Routine repeat head CT may not be necessary for patients with mild TBI

PubMed Central

Rosen, Claire B; Luy, Diego D; Deane, Molly R; Scalea, Thomas M; Stein, Deborah M

2018-01-01

Background Routine repeat cranial CT (RHCT) is standard of care for CT-verified traumatic brain injury (TBI). Despite mixed evidence, those with mild TBI are subject to radiation and expense from serial CT scans. Thus, we investigated the necessity and utility of RHCT for patients with mild TBI. We hypothesized that repeat head CT in these patients would not alter patient care or outcomes. Methods We retrospectively studied patients suffering from mild TBI (Glasgow Coma Scale (GCS) score 13–15) and treated at the R Adams Cowley Shock Trauma Center from November 2014 through January 2015. The primary outcome was the need for surgical intervention. Outcomes were compared using paired Student’s t-test, and stratified by injury on initial CT, GCS change, demographics, and presenting vital signs (mean ± SD). Results Eighty-five patients met inclusion criteria with an average initial GCS score=14.6±0.57. Our center sees about 2800 patients with TBI per year, or about 230 per month. This includes patients with concussions. This sample represents about 30% of patients with TBI seen during the study period. Ten patients required operation (four based on initial CT and others for worsening GCS, headaches, large unresolving injury). There was progression of injury on repeat CT scan in only two patients that required operation, and this accompanied clinical deterioration. The mean brain Abbreviated Injury Scale (AIS) score was 4.8±0.3 for surgical patients on initial CT scan compared with 3.4±0.6 (P<0.001) for non-surgical patients. Initial CT subdural hematoma size was 1.1±0.6 cm for surgical patients compared with 0.49±0.3 cm (P=0.05) for non-surgical patients. There was no significant difference between intervention groups in terms of other intracranial injuries, demographics, vital signs, or change in GCS. Overall, 75 patients that did not require surgical intervention received RHCT. At $340 per CT, $51 000 was spent on unnecessary imaging ($367 000/year, extrapolated). Discussion In an environment of increased scrutiny on healthcare expenditures, it is necessary to question dogma and eliminate unnecessary cost. Our data questions the use of routine repeat head CT scans in every patient with anatomic TBI and suggests that clinically stable patients with small injury can simply be followed clinically. Level of evidence Level III. PMID:29766124

Comparison of eye lens dose on neuroimaging protocols between 16- and 64-section multidetector CT: achieving the lowest possible dose.

PubMed

Tan, J S P; Tan, K-L; Lee, J C L; Wan, C-M; Leong, J-L; Chan, L-L

2009-02-01

To our knowledge, there has been no study that compares the radiation dose delivered to the eye lens by 16- and 64-section multidetector CT (MDCT) for standard clinical neuroimaging protocols. Our aim was to assess radiation-dose differences between 16- and 64-section MDCT from the same manufacturer, by using near-identical neuroimaging protocols. Three cadaveric heads were scanned on 16- and 64-section MDCT by using standard neuroimaging CT protocols. Eye lens dose was measured by using thermoluminescent dosimeters (TLD), and each scanning was repeated to reduce random error. The dose-length product, volume CT dose index (CTDI(vol)), and TLD readings for each imaging protocol were averaged and compared between scanners and protocols, by using the paired Student t test. Statistical significance was defined at P < .05. The radiation dose delivered and eye lens doses were lower by 28.1%-45.7% (P < .000) on the 64-section MDCT for near-identical imaging protocols. On the 16-section MDCT, lens dose reduction was greatest (81.1%) on a tilted axial mode, compared with a nontilted helical mode for CT brain scans. Among the protocols studied, CT of the temporal bone delivered the greatest radiation dose to the eye lens. Eye lens radiation doses delivered by the 64-section MDCT are significantly lower, partly due to improvements in automatic tube current modulation technology. However, where applicable, protection of the eyes from the radiation beam by either repositioning the head or tilting the gantry remains the best way to reduce eye lens dose.

Multislice CT of the head and body routine scans: Are scanning protocols adjusted for paediatric patients?

PubMed Central

Sun, Z; Al Ghamdi, KS; Baroum, IH

2012-01-01

Purpose: To investigate whether the multislice CT scanning protocols of head, chest and abdomen are adjusted according to patient’s age in paediatric patients. Materials and Methods: Multislice CT examination records of paediatric patients undergoing head, chest and abdomen scans from three public hospitals during a one-year period were retrospectively reviewed. Patients were categorised into the following age groups: under 4 years, 5–8 years, 9–12 years and 13–16 years, while the tube current was classified into the following ranges: < 49 mA, 50–99 mA, 100–149 mA, 150–199 mA, > 200 mA and unknown. Results: A total of 4998 patient records, comprising a combination of head, chest and abdomen CT scans, were assessed, with head CT scans representing nearly half of the total scans. Age-based adjusted CT protocols were observed in most of the scans with higher tube current setting being used with increasing age. However, a high tube current (150–199 mA) was still used in younger patients (0–8 years) undergoing head CT scans. In one hospital, CT protocols remained constant across all age groups, indicating potential overexposure to the patients. Conclusion: This analysis shows that paediatric CT scans are adjusted according to the patient’s age in most of the routine CT examinations. This indicates increased awareness regarding radiation risks associated with CT. However, high tube current settings are still used in younger patient groups, thus, optimisation of paediatric CT protocols and implementation of current guidelines, such as age-and weight-based scanning, should be recommended in daily practice. PMID:22970059

Clinical values of (18) F-FDG PET/CT in oral cavity cancer with dental artifacts on CT or MRI.

PubMed

Hong, Hye Ran; Jin, Soyoung; Koo, Hyun Jung; Roh, Jong-Lyel; Kim, Jae Seung; Cho, Kyung-Ja; Choi, Seung-Ho; Nam, Soon Yuhl; Kim, Sang Yoon

2014-11-01

2a To investigate the role of (18) F-FDG PET/CT in tumor staging, extent, and volume measurements in oral cavity squamous cell carcinoma (OSCC) patients with/without dental artifacts on CT or MRI. This study was conducted in 63 consecutive patients with OSCC who received initial workups including (18) F-FDG PET/CT and MRI. The results of the imaging modalities were compared to those of pathology, using McNemar's test and the paired t-test. Thirty-seven patients (59%) had dental or metallic artifacts obscuring primary tumors. (18) F-FDG PET/CT scanning was superior to MRI in tumor staging (weighted κ = 0.870 vs. 0.518, P = 0.004) in patients with dental artifacts. In addition, (18) F-FDG PET/CT scans were more specific than MRI in detecting sublingual gland (P = 0.014) and mouth floor (P = 0.011) involvement. In patients with dental artifacts, there was a significant discrepancy between primary tumor volume (PTV) measured by pathology and MRI (P = 0.018), but not between PTV measured from pathology and (18) F-FDG PET/CT at SUV2.5 (P = 0.245), which showed the highest intraclass correlation coefficient value (0.860). (18) F-FDG PET/CT scans provide accurate tumor staging and volume measurements in OSCC patients with CR/MRI dental artifacts, leading to improved preoperative planning. 2b CONDENSED ABSTRACT This study evaluated the clinical value of (18) F-FDG PET/CT in 63 patients with oral cavity cancers. In 37 (59%) patients with dental artifacts on CT/MRI, (18) F-FDG PET/CT showed superior results compared to MRI in tumor staging and represented the highest intraclass correlation coefficient value to tumor volume determined by pathology. © 2014 Wiley Periodicals, Inc.

Accuracy of epicardial electroanatomic mapping and ablation of sustained ventricular tachycardia merged with heart CT scan in chronic Chagasic cardiomyopathy.

PubMed

Valdigem, Bruno Pereira; da Silva, Nilton José Carneiro; Dietrich, Cristiano Oliveira; Moreira, Dalmo; Sasdelli, Roberto; Pinto, Ibraim M; Cirenza, Claudio; de Paola, Angelo Amato Vincenzo

2010-11-01

As damage to coronary arteries is a potential complication of epicardial RF catheter ablation (EPRFCA), the procedure must be associated with coronary angiography. Chronic Chagasic cardiomiopathy (CCC) is a disease where epicardial VT are common. Eletroanatomic mapping merged with computed totmography (CT) scan data is a useful tool for mapping the endocardium, and its accuracy in guiding ablation on the epicardium was not adequately evaluated so far. Compare electronatomic map merged with Heart CT to fluoroscopy for epicardial ablation of CCC. Describe the distribution of the scars on CCC. We performed epicardial and endocardial mapping and ablation using CARTO XP V8 on eight patients and merged the map with coronary arteries CT scan using at least three landmarks. To compare the 3D image obtained with CARTO MERGE and the 2D fluoroscopic image obtained during the ablation procedure, we used computer graphic software (Inkscape™) in order to prove that the images were equivalent and to compare the distance between the catheter tip on fluoroscopy to catheter tip on 3D EA map. EPRFCA was successfully performed in all patients and they did not present recurrence for at least 3-month follow-up. The mean difference between the tip of the catheter on fluoroscopy and on the 3D model was 6.03 ± 2.09 mm. Scars were present in the epicardium and endocardium and most of patients presented with posterior wall scars and RV scar. The combination of electroanatomic map and CT coronary artery scan data is feasible and can be an important tool for EPRFCA in patients with CCC and VT.

Periprosthetic osteolysis after AES total ankle replacement: Conventional radiography versus CT-scan.

PubMed

Viste, Anthony; Al Zahrani, Nader; Brito, Nuno; Lienhart, Christophe; Fessy, Michel Henri; Besse, Jean-Luc

2015-09-01

The aim of this study was to compare conventional X-rays and CT-scan in detecting peri-prosthetic osteolytic lesions, a major concern after total ankle replacement (TAR). We prospectively assessed 50 patients (mean age 56 years), consecutively operated on by the same senior surgeon, between 2003 and 2006 and with a mean follow-up period of 4 years (range, 2-6.2). The component used was AES total ankle replacement. The etiologies for total ankle arthroplasty were: posttraumatic in 50%, osteoarthritis secondary to instability in 36%. Plain radiographs were analyzed by 4 independent observers, using a 10-zone protocol (location) and 5 size categories. At 4-year follow-up, all patients had been CT-scan assessed with the same protocol by 2 independent observers. Plain radiographs showed dramatic progression of severe periprosthetic lyses (>10mm): from 14% to 36% of interface cysts for the tibial component respectively at 2 and 4-year follow-up and from 4% to 30% for the talar implant. The talar component was more accurately assessed by CT-scan (mean frontal and sagittal talar lesion: from 270 mm2 to 288 mm2 for CT-scan versus 133 mm2 to 174 mm2 for X-rays). For tibial cysts, axial views showed larger lesions (313 mm2 than frontal (194 mm2) or sagittal (213.5 mm2) views. At 4-year follow-up, 24% of patients had revision with curetage or arthrodesis, and at 7 years follow-up 38% were revised. These results are similar to recent AES series, justifying withdrawal of this device. CT-scan was more accurate than X-rays for detecting and quantifying periprosthetic osteolysis. We recommend a yearly radiological control and CT-scan in case of lesion on X-rays. Copyright © 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

What is the best imaging strategy for acute stroke?

PubMed

Wardlaw, J M; Keir, S L; Seymour, J; Lewis, S; Sandercock, P A G; Dennis, M S; Cairns, J

2004-01-01

To determine the cost-effectiveness of computed tomographic (CT) scanning after acute stroke. To assess the contribution of brain imaging to the diagnosis and management of stroke, and to estimate the costs, benefits and risks of different imaging strategies in order to provide data to inform national and local policy on the use of brain imaging in stroke. A decision-analysis model was developed to represent the pathway of care in acute stroke using 'scan all patients within 48 hours' as the comparator against which to cost 12 alternative scan strategies. Hospitals in Scotland. Subjects were patients admitted to hospital with a first stroke and those managed as outpatients. The effect on functional outcome after ischaemic or haemorrhagic stroke, tumours or infections, of correctly administered antithrombotic or other treatment; of time to scan and stroke severity on diagnosis by CT or MRI; on management, including length of stay, functional outcome, and quality-adjusted life years (QALYs), of the diagnostic information provided by CT scanning; the cost-effectiveness (cost versus QALYs) of different strategies for use of CT after acute stroke. Death and functional outcome at long-term follow-up; accuracy of CT and MRI; cost of CT scanning by time of day and week; effect of CT diagnosis on change in health outcome, length of stay in hospital and QALYs; cost-effectiveness of various scanning strategies. CT is very sensitive and specific for haemorrhage within the first 8 days of stroke only. Suboptimal scanning used in epidemiology studies suggests that the frequency of primary intracerebral haemorrhage (PICH) has been underestimated. Aspirin increases the risk of PICH. There were no reliable data on functional outcome or on the effect of antithrombotic treatment given long term after PICH. In 60% of patients with recurrent stroke after PICH, the cause is another PICH and mortality is high among PICH patients. A specific MR sequence (gradient echo) is required to identify prior PICH reliably. CT scanners were distributed unevenly in Scotland, 65% provided CT scanning within 48 hours of stroke, and 100% within 7 days for hospital-admitted patients, but access out of hours was very variable, and for outpatients was poor. The average cost of a CT brain scan for stroke was pounds 30.23 to pounds 89.56 in normal working hours and pounds 55.05 to pounds 173.46 out of hours. Average length of stay was greatest for severe strokes and those who survived in a dependent state. For a cohort of 1000 patients aged 70-74 years, the policy 'scan all strokes within 48 hours', cost pounds 10,279,728 and achieved 1982.3 QALYS. The most cost-effective strategy was 'scan all immediately' (pounds 9,993,676 and 1982.4 QALYS). The least cost-effective was to 'scan patients on anticoagulants, in a life-threatening condition immediately and the rest within 14 days'. In general, strategies in which most patients were scanned immediately cost least and achieved the most QALYs, as the cost of providing CT (even out of hours) was less than the cost of inpatient care. Increasing independent survival by even a small proportion through early use of aspirin in the majority with ischaemic stroke, avoiding aspirin in those with haemorrhagic stroke, and appropriate early management of those who have not had a stroke, reduced costs and increased QALYs.

Attenuation correction of emission PET images with average CT: Interpolation from breath-hold CT

NASA Astrophysics Data System (ADS)

Huang, Tzung-Chi; Zhang, Geoffrey; Chen, Chih-Hao; Yang, Bang-Hung; Wu, Nien-Yun; Wang, Shyh-Jen; Wu, Tung-Hsin

2011-05-01

Misregistration resulting from the difference of temporal resolution in PET and CT scans occur frequently in PET/CT imaging, which causes distortion in tumor quantification in PET. Respiration cine average CT (CACT) for PET attenuation correction has been reported to improve the misalignment effectively by several papers. However, the radiation dose to the patient from a four-dimensional CT scan is relatively high. In this study, we propose a method to interpolate respiratory CT images over a respiratory cycle from inhalation and exhalation breath-hold CT images, and use the average CT from the generated CT set for PET attenuation correction. The radiation dose to the patient is reduced using this method. Six cancer patients of various lesion sites underwent routine free-breath helical CT (HCT), respiration CACT, interpolated average CT (IACT), and 18F-FDG PET. Deformable image registration was used to interpolate the middle phases of a respiratory cycle based on the end-inspiration and end-expiration breath-hold CT scans. The average CT image was calculated from the eight interpolated CT image sets of middle respiratory phases and the two original inspiration and expiration CT images. Then the PET images were reconstructed by these three methods for attenuation correction using HCT, CACT, and IACT. Misalignment of PET image using either CACT or IACT for attenuation correction in PET/CT was improved. The difference in standard uptake value (SUV) from tumor in PET images was most significant between the use of HCT and CACT, while the least significant between the use of CACT and IACT. Besides the similar improvement in tumor quantification compared to the use of CACT, using IACT for PET attenuation correction reduces the radiation dose to the patient.

Low Yield of Paired Head and Cervical Spine Computed Tomography in Blunt Trauma Evaluation.

PubMed

Graterol, Joseph; Beylin, Maria; Whetstone, William D; Matzoll, Ashleigh; Burke, Rennie; Talbott, Jason; Rodriguez, Robert M

2018-06-01

With increased computed tomography (CT) utilization, clinicians may simultaneously order head and neck CT scans, even when injury is suspected only in one region. We sought to determine: 1) the frequency of simultaneous ordering of a head CT scan when a neck CT scan is ordered; 2) the yields of simultaneously ordered head and neck CT scans for clinically significant injury (CSI); and 3) whether injury in one region is associated with a higher rate of injury in the other. This was a retrospective study of all adult patients who received neck CT scans (and simultaneously ordered head CT scans) as part of their blunt trauma evaluation at an urban level 1 trauma center in 2013. An expert panel determined CSI of head and neck injuries. We defined yield as number of patients with injury/number of patients who had a CT scan. Of 3223 patients who met inclusion criteria, 2888 (89.6%) had simultaneously ordered head and neck CT scans. CT yield for CSI in both the head and neck was 0.5% (95% confidence interval [CI] 0.3-0.8%), and the yield for any injury in both the head and neck was 1.4% (95% CI 1.0-1.8%). The yield for CSI in one region was higher when CSI was seen in the other region. The yield of CT for CSI in both the head and neck concomitantly is very low. When injury is seen in one region, there is higher likelihood of injury in the other. These findings argue against paired ordering of head and neck CT scans and suggest that CT scans should be ordered individually or when injury is detected in one region. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparative evaluation of image quality among different detector configurations using area detector computed tomography.

PubMed

Miura, Yohei; Ichikawa, Katsuhiro; Fujimura, Ichiro; Hara, Takanori; Hoshino, Takashi; Niwa, Shinji; Funahashi, Masao

2018-03-01

The 320-detector row computed tomography (CT) system, i.e., the area detector CT (ADCT), can perform helical scanning with detector configurations of 4-, 16-, 32-, 64-, 80-, 100-, and 160-detector rows for routine CT examinations. This phantom study aimed to compare the quality of images obtained using helical scan mode with different detector configurations. The image quality was measured using modulation transfer function (MTF) and noise power spectrum (NPS). The system performance function (SP), based on the pre-whitening theorem, was calculated as MTF 2 /NPS, and compared between configurations. Five detector configurations, i.e., 0.5 × 16 mm (16 row), 0.5 × 64 mm (64 row), 0.5 × 80 mm (80 row), 0.5 × 100 mm (100 row), and 0.5 × 160 mm (160 row), were compared using a constant volume CT dose index (CTDI vol ) of 25 mGy, simulating the scan of an adult abdomen, and with a constant effective mAs value. The MTF was measured using the wire method, and the NPS was measured from images of a 20-cm diameter phantom with uniform content. The SP of 80-row configuration was the best, for the constant CTDI vol , followed by the 64-, 160-, 16-, and 100-row configurations. The decrease in the rate of the 100- and 160-row configurations from the 80-row configuration was approximately 30%. For the constant effective mAs, the SPs of the 100-row and 160-row configurations were significantly lower, compared with the other three detector configurations. The 80- and 64-row configurations were adequate in cases that required dose efficiency rather than scan speed.

Fracture Prediction by Computed Tomography and Finite Element Analysis: Current and Future Perspectives.

PubMed

Johannesdottir, Fjola; Allaire, Brett; Bouxsein, Mary L

2018-05-30

This review critiques the ability of CT-based methods to predict incident hip and vertebral fractures. CT-based techniques with concurrent calibration all show strong associations with incident hip and vertebral fracture, predicting hip and vertebral fractures as well as, and sometimes better than, dual-energy X-ray absorptiometry areal biomass density (DXA aBMD). There is growing evidence for use of routine CT scans for bone health assessment. CT-based techniques provide a robust approach for osteoporosis diagnosis and fracture prediction. It remains to be seen if further technical advances will improve fracture prediction compared to DXA aBMD. Future work should include more standardization in CT analyses, establishment of treatment intervention thresholds, and more studies to determine whether routine CT scans can be efficiently used to expand the number of individuals who undergo evaluation for fracture risk.

Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study

PubMed Central

Pearce, Mark S; Salotti, Jane A; Little, Mark P; McHugh, Kieran; Lee, Choonsik; Kim, Kwang Pyo; Howe, Nicola L; Ronckers, Cecile M; Rajaraman, Preetha; Craft, Alan W; Parker, Louise; de González, Amy Berrington

2012-01-01

Summary Background Although CT scans are very useful clinically, potential cancer risks exist from associated ionising radiation, in particular for children who are more radiosensitive than adults. We aimed to assess the excess risk of leukaemia and brain tumours after CT scans in a cohort of children and young adults. Methods In our retrospective cohort study, we included patients without previous cancer diagnoses who were first examined with CT in National Health Service (NHS) centres in England, Wales, or Scotland (Great Britain) between 1985 and 2002, when they were younger than 22 years of age. We obtained data for cancer incidence, mortality, and loss to follow-up from the NHS Central Registry from Jan 1, 1985, to Dec 31, 2008. We estimated absorbed brain and red bone marrow doses per CT scan in mGy and assessed excess incidence of leukaemia and brain tumours cancer with Poisson relative risk models. To avoid inclusion of CT scans related to cancer diagnosis, follow-up for leukaemia began 2 years after the first CT and for brain tumours 5 years after the first CT. Findings During follow-up, 74 of 178 604 patients were diagnosed with leukaemia and 135 of 176 587 patients were diagnosed with brain tumours. We noted a positive association between radiation dose from CT scans and leukaemia (excess relative risk [ERR] per mGy 0·036, 95% CI 0·005–0·120; p=0·0097) and brain tumours (0·023, 0·010–0·049; p<0·0001). Compared with patients who received a dose of less than 5 mGy, the relative risk of leukaemia for patients who received a cumulative dose of at least 30 mGy (mean dose 51·13 mGy) was 3·18 (95% CI 1·46–6·94) and the relative risk of brain cancer for patients who received a cumulative dose of 50–74 mGy (mean dose 60·42 mGy) was 2·82 (1·33–6·03). Interpretation Use of CT scans in children to deliver cumulative doses of about 50 mGy might almost triple the risk of leukaemia and doses of about 60 mGy might triple the risk of brain cancer. Because these cancers are relatively rare, the cumulative absolute risks are small: in the 10 years after the first scan for patients younger than 10 years, one excess case of leukaemia and one excess case of brain tumour per 10 000 head CT scans is estimated to occur. Nevertheless, although clinical benefits should outweigh the small absolute risks, radiation doses from CT scans ought to be kept as low as possible and alternative procedures, which do not involve ionising radiation, should be considered if appropriate. Funding US National Cancer Institute and UK Department of Health. PMID:22681860

Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study.

PubMed

Pearce, Mark S; Salotti, Jane A; Little, Mark P; McHugh, Kieran; Lee, Choonsik; Kim, Kwang Pyo; Howe, Nicola L; Ronckers, Cecile M; Rajaraman, Preetha; Sir Craft, Alan W; Parker, Louise; Berrington de González, Amy

2012-08-04

Although CT scans are very useful clinically, potential cancer risks exist from associated ionising radiation, in particular for children who are more radiosensitive than adults. We aimed to assess the excess risk of leukaemia and brain tumours after CT scans in a cohort of children and young adults. In our retrospective cohort study, we included patients without previous cancer diagnoses who were first examined with CT in National Health Service (NHS) centres in England, Wales, or Scotland (Great Britain) between 1985 and 2002, when they were younger than 22 years of age. We obtained data for cancer incidence, mortality, and loss to follow-up from the NHS Central Registry from Jan 1, 1985, to Dec 31, 2008. We estimated absorbed brain and red bone marrow doses per CT scan in mGy and assessed excess incidence of leukaemia and brain tumours cancer with Poisson relative risk models. To avoid inclusion of CT scans related to cancer diagnosis, follow-up for leukaemia began 2 years after the first CT and for brain tumours 5 years after the first CT. During follow-up, 74 of 178,604 patients were diagnosed with leukaemia and 135 of 176,587 patients were diagnosed with brain tumours. We noted a positive association between radiation dose from CT scans and leukaemia (excess relative risk [ERR] per mGy 0·036, 95% CI 0·005-0·120; p=0·0097) and brain tumours (0·023, 0·010-0·049; p<0·0001). Compared with patients who received a dose of less than 5 mGy, the relative risk of leukaemia for patients who received a cumulative dose of at least 30 mGy (mean dose 51·13 mGy) was 3·18 (95% CI 1·46-6·94) and the relative risk of brain cancer for patients who received a cumulative dose of 50-74 mGy (mean dose 60·42 mGy) was 2·82 (1·33-6·03). Use of CT scans in children to deliver cumulative doses of about 50 mGy might almost triple the risk of leukaemia and doses of about 60 mGy might triple the risk of brain cancer. Because these cancers are relatively rare, the cumulative absolute risks are small: in the 10 years after the first scan for patients younger than 10 years, one excess case of leukaemia and one excess case of brain tumour per 10,000 head CT scans is estimated to occur. Nevertheless, although clinical benefits should outweigh the small absolute risks, radiation doses from CT scans ought to be kept as low as possible and alternative procedures, which do not involve ionising radiation, should be considered if appropriate. US National Cancer Institute and UK Department of Health. Copyright © 2012 Elsevier Ltd. All rights reserved.

Organ dose measurement using Optically Stimulated Luminescence Detector (OSLD) during CT examination

NASA Astrophysics Data System (ADS)

Yusuf, Muhammad; Alothmany, Nazeeh; Abdulrahman Kinsara, Abdulraheem

2017-10-01

This study provides detailed information regarding the imaging doses to patient radiosensitive organs from a kilovoltage computed tomography (CT) scan procedure using OSLD. The study reports discrepancies between the measured dose and the calculated dose from the ImPACT scan, as well as a comparison with the dose from a chest X-ray radiography procedure. OSLDs were inserted in several organs, including the brain, eyes, thyroid, lung, heart, spinal cord, breast, spleen, stomach, liver and ovaries, of the RANDO phantom. Standard clinical scanning protocols were used for each individual site, including the brain, thyroid, lung, breast, stomach, liver and ovaries. The measured absorbed doses were then compared with the simulated dose obtained from the ImPACT scan. Additionally, the equivalent doses for each organ were calculated and compared with the dose from a chest X-ray radiography procedure. Absorbed organ doses measured by OSLD in the RANDO phantom of up to 17 mGy depend on the organ scanned and the scanning protocols used. A maximum 9.82% difference was observed between the target organ dose measured by OSLD and the results from the ImPACT scan. The maximum equivalent organ dose measured during this experiment was equal to 99.899 times the equivalent dose from a chest X-ray radiography procedure. The discrepancies between the measured dose with the OSLD and the calculated dose from the ImPACT scan were within 10%. This report recommends the use of OSLD for measuring the absorbed organ dose during CT examination.

An audit of imaging test utilization for the management of lymphoma in an oncology hospital: implications for resource planning?

PubMed

Schwartz, A; Gospodarowicz, M K; Khalili, K; Pintilie, M; Goddard, S; Keller, A; Tsang, R W

2006-02-01

The purpose of this study was to assist with resource planning by examining the pattern of physician utilization of imaging procedures for lymphoma patients in a dedicated oncology hospital. The proportion of imaging tests ordered for routine follow up with no specific clinical indication was quantified, with specific attention to CT scans. A 3-month audit was performed. The reasons for ordering all imaging procedures (X-rays, CT scans, ultrasound, nuclear scan and MRI) were determined through a retrospective chart review. 411 lymphoma patients had 686 assessments (sets of imaging tests) and 981 procedures (individual imaging tests). Most procedures were CT scans (52%) and chest radiographs (30%). The most common reasons for ordering imaging were assessing response (23%), and investigating new symptoms (19%). Routine follow up constituted 21% of the assessments (142/686), and of these, 82% were chest radiographs (116/142), while 24% (34/142) were CT scans. With analysis restricted to CT scans (296 assessments in 248 patients), the most common reason for ordering CT scans were response evaluation (40%), and suspicion of recurrence and/or new symptom (23%). Follow-up CT scans done with no clinical indication comprised 8% (25/296) of all CT assessments. Staging CT scans were under-represented at 6% of all assessments. Imaging with CT scans for follow up of asymptomatic patients is infrequent. However, scans done for staging new lymphoma patients were unexpectedly low in frequency, due to scans done elsewhere prior to referral. This analysis uncovered utilization patterns, helped resource planning and provided data to reduce unnecessary imaging procedures.

Implementation of a CT Scan Practice Guideline for Pediatric Trauma Patients Reduces Unnecessary Scans Without Impacting Outcomes.

PubMed

McGrew, Patrick R; Chestovich, Paul J; Fisher, Jay D; Kuhls, Deborah A; Fraser, Douglas R; Patel, Purvi P; Katona, Chad W; Saquib, Syed; Fildes, John J

2018-05-04

Computed Tomography (CT) scans are useful in the evaluation of trauma patients, but are costly and pose risks from ionizing radiation in children. Recent literature has demonstrated the utility of CT scan guidelines in the management of pediatric trauma. This study objective is to review our treatment of pediatric blunt trauma patients and evaluate CT utilization before and after CT-guideline implementation. Our Pediatric Level 2 Trauma Center (TC) implemented a CT scan practice guideline for pediatric trauma patients in March 2014. The guideline recommended for or against CT of the head and abdomen/pelvis utilizing published criteria from the Pediatric Emergency Care and Research Network (PECARN). There was no chest CT guideline. We reviewed all pediatric trauma patients for CT scans obtained during initial evaluation before and after guideline implementation, excluding inpatient scans. The Trauma Registry Database was queried to include all pediatric (age<15) trauma patients seen in our TC from 2010-2016, excluding penetrating mechanism and deaths in the TC. Scans were considered positive if organ injury was detected. Primary outcome was the proportion of patients undergoing CT and percent positive CTs. Secondary outcomes were hospital length of stay (LOS), readmissions, and mortality. Categorical and continuous variables were analyzed with Chi-square and Wilcoxon rank-sum tests, respectively. P<0.05 was considered significant. We identified 1934 patients: 1106 pre- and 828 post-guideline. Absolute reductions in head, chest, and abdomen/pelvis CT scans were 17.7%, 11.5%, and 18.8% respectively (p<0.001). Percent positive head CTs were equivalent, but percent positive chest and abdomen CT increased after implementation. Secondary outcomes were unchanged. Implementation of a pediatric CT guideline significantly decreases CT utilization, reducing the radiation exposure without a difference in outcome. Trauma centers treating pediatric patients should adopt similar guidelines to decrease unnecessary CT scans in children. Level IV, Therapeutic Study.

Prediction of thoracic dimensions and spine length on the basis of individual pelvic dimensions: validation of the use of pelvic inlet width obtained by radiographs compared with computed tomography.

PubMed

Gold, Meryl; Dombek, Michael; Miller, Patricia E; Emans, John B; Glotzbecker, Michael P

2014-01-01

Retrospective review. To validate the pelvic inlet width (PIW) measurement obtained on radiograph as an independent standard used to correlate with thoracic dimensions (TDs) in treated and untreated patients with early-onset scoliosis. In children with early-onset scoliosis, the change in TD and spine length is a key treatment goal. Quantifying this change is confounded by varied growth rates and differing diagnoses. PIW measured on computed tomographic (CT) scan in patients without scoliosis has been shown to correlate with TD in an age-independent manner. The first arm included 49 patients with scoliosis who had both a CT scan and pelvic radiograph. Agreement between PIW measurements on CT scan and radiograph was analyzed. The second arm consisted of 163 patients (age, 0.2-18.7 yr), with minimal spinal deformity (mean Cobb, 9.0°) and radiographs in which PIW was measurable. PIW was compared with previously published CT-based TD measurements; maximal chest width, T1-T12 height, and T1-S1 height. Linear regression analysis was used to develop and validate sex-specific predictive equations for each TD measurement on the basis of PIW. Interobserver reliability was evaluated for all measurements. Bland-Altman analysis indicated agreement with no dependence on observed value, but a consistent 8.5 mm (95% CI: 7.2-9.9 mm) difference in CT scan measurement compared with radiographical PIW measurement. Sex and PIW were significantly correlated to each TD measurement (P < 0.01). Predictive models were validated and may be used to estimate TD measurements on the basis of sex and radiographical PIW. Intraclass correlation coefficients for all measurements were between 0.978 and 0.997. PIW on radiographs and CT scan correlate in patients with deformity and with spine and TD in patients with minimal deformity. It is a fast, reliable method of assessing growth while lowering patient's radiation exposure. It can be reliably used to assess patients with early-onset scoliosis and the impact surgical treatment has on chest and spinal growth. 3.

NEOadjuvant therapy monitoring with PET and CT in Esophageal Cancer (NEOPEC-trial)

PubMed Central

2008-01-01

Background Surgical resection is the preferred treatment of potentially curable esophageal cancer. To improve long term patient outcome, many institutes apply neoadjuvant chemoradiotherapy. In a large proportion of patients no response to chemoradiotherapy is achieved. These patients suffer from toxic and ineffective neoadjuvant treatment, while appropriate surgical therapy is delayed. For this reason a diagnostic test that allows for accurate prediction of tumor response early during chemoradiotherapy is of crucial importance. CT-scan and endoscopic ultrasound have limited accuracy in predicting histopathologic tumor response. Data suggest that metabolic changes in tumor tissue as measured by FDG-PET predict response better. This study aims to compare FDG-PET and CT-scan for the early prediction of non-response to preoperative chemoradiotherapy in patients with potentially curable esophageal cancer. Methods/design Prognostic accuracy study, embedded in a randomized multicenter Dutch trial comparing neoadjuvant chemoradiotherapy for 5 weeks followed by surgery versus surgery alone for esophageal cancer. This prognostic accuracy study is performed only in the neoadjuvant arm of the randomized trial. In 6 centers, 150 consecutive patients will be included over a 3 year period. FDG-PET and CT-scan will be performed before and 2 weeks after the start of the chemoradiotherapy. All patients complete the 5 weeks regimen of neoadjuvant chemoradiotherapy, regardless the test results. Pathological examination of the surgical resection specimen will be used as reference standard. Responders are defined as patients with < 10% viable residual tumor cells (Mandard-score). Difference in accuracy (area under ROC curve) and negative predictive value between FDG-PET and CT-scan are primary endpoints. Furthermore, an economic evaluation will be performed, comparing survival and costs associated with the use of FDG-PET (or CT-scan) to predict tumor response with survival and costs of neoadjuvant chemoradiotherapy without prediction of response (reference strategy). Discussion The NEOPEC-trial could be the first sufficiently powered study that helps justify implementation of FDG-PET for response-monitoring in patients with esophageal cancer in clinical practice. Trial registration ISRCTN45750457 PMID:18671847

Normalization of CT scans reconstructed with different kernels to reduce variability in emphysema measurements

NASA Astrophysics Data System (ADS)

Gallardo Estrella, L.; van Ginneken, B.; van Rikxoort, E. M.

2013-03-01

Chronic Obstructive Pulmonary Disease (COPD) is a lung disease characterized by progressive air flow limitation caused by emphysema and chronic bronchitis. Emphysema is quantified from chest computed tomography (CT) scans as the percentage of attentuation values below a fixed threshold. The emphysema quantification varies substantially between scans reconstructed with different kernels, limiting the possibilities to compare emphysema quantifications obtained from scans with different reconstruction parameters. In this paper we propose a method to normalize scans reconstructed with different kernels to have the same characteristics as scans reconstructed with a reference kernel and investigate if this normalization reduces the variability in emphysema quantification. The proposed normalization splits a CT scan into different frequency bands based on hierarchical unsharp masking. Normalization is performed by changing the energy in each frequency band to the average energy in each band in the reference kernel. A database of 15 subjects with COPD was constructed for this study. All subjects were scanned at total lung capacity and the scans were reconstructed with four different reconstruction kernels. The normalization was applied to all scans. Emphysema quantification was performed before and after normalization. It is shown that the emphysema score varies substantially before normalization but the variation diminishes after normalization.

Is the routine CT head scan justified for psychiatric patients? A prospective study.

PubMed Central

Ananth, J; Gamal, R; Miller, M; Wohl, M; Vandewater, S

1993-01-01

Thirty-four psychiatric patients, assessed for a physical illness that was missed during diagnosis, underwent a CT scan. After investigation, the diagnosis of 14 patients changed from a functional to an organic illness. In nine patients, the CT scan was reported to be abnormal, and yet only two were diagnosed as having an organic syndrome. In seven patients, the CT scan was normal but the patients had an undisputed organic brain syndrome. These findings indicate that the use of CT scans should be restricted to cases in which the diagnosis is seriously in question. The clinical findings should dictate the use of CT scans either to clarify or to complement them. PMID:8461285

Mass preserving registration for lung CT

NASA Astrophysics Data System (ADS)

Gorbunova, Vladlena; Lo, Pechin; Loeve, Martine; Tiddens, Harm A.; Sporring, Jon; Nielsen, Mads; de Bruijne, Marleen

2009-02-01

In this paper, we evaluate a novel image registration method on a set of expiratory-inspiratory pairs of computed tomography (CT) lung scans. A free-form multi resolution image registration technique is used to match two scans of the same subject. To account for the differences in the lung intensities due to differences in inspiration level, we propose to adjust the intensity of lung tissue according to the local expansion or compression. An image registration method without intensity adjustment is compared to the proposed method. Both approaches are evaluated on a set of 10 pairs of expiration and inspiration CT scans of children with cystic fibrosis lung disease. The proposed method with mass preserving adjustment results in significantly better alignment of the vessel trees. Analysis of local volume change for regions with trapped air compared to normally ventilated regions revealed larger differences between these regions in the case of mass preserving image registration, indicating that mass preserving registration is better at capturing localized differences in lung deformation.

Dynamic volume vs respiratory correlated 4DCT for motion assessment in radiation therapy simulation.

PubMed

Coolens, Catherine; Bracken, John; Driscoll, Brandon; Hope, Andrew; Jaffray, David

2012-05-01

Conventional (i.e., respiratory-correlated) 4DCT exploits the repetitive nature of breathing to provide an estimate of motion; however, it has limitations due to binning artifacts and irregular breathing in actual patient breathing patterns. The aim of this work was to evaluate the accuracy and image quality of a dynamic volume, CT approach (4D(vol)) using a 320-slice CT scanner to minimize these limitations, wherein entire image volumes are acquired dynamically without couch movement. This will be compared to the conventional respiratory-correlated 4DCT approach (RCCT). 4D(vol) CT was performed and characterized on an in-house, programmable respiratory motion phantom containing multiple geometric and morphological "tumor" objects over a range of regular and irregular patient breathing traces obtained from 3D fluoroscopy and compared to RCCT. The accuracy of volumetric capture and breathing displacement were evaluated and compared with the ground truth values and with the results reported using RCCT. A motion model was investigated to validate the number of motion samples needed to obtain accurate motion probability density functions (PDF). The impact of 4D image quality on this accuracy was then investigated. Dose measurements using volumetric and conventional scan techniques were also performed and compared. Both conventional and dynamic volume 4DCT methods were capable of estimating the programmed displacement of sinusoidal motion, but patient breathing is known to not be regular, and obvious differences were seen for realistic, irregular motion. The mean RCCT amplitude error averaged at 4 mm (max. 7.8 mm) whereas the 4D(vol) CT error stayed below 0.5 mm. Similarly, the average absolute volume error was lower with 4D(vol) CT. Under irregular breathing, the 4D(vol) CT method provides a close description of the motion PDF (cross-correlation 0.99) and is able to track each object, whereas the RCCT method results in a significantly different PDF from the ground truth, especially for smaller tumors (cross-correlation ranging between 0.04 and 0.69). For the protocols studied, the dose measurements were higher in the 4D(vol) CT method (40%), but it was shown that significant mAs reductions can be achieved by a factor of 4-5 while maintaining image quality and accuracy. 4D(vol) CT using a scanner with a large cone-angle is a promising alternative for improving the accuracy with which respiration-induced motion can be characterized, particularly for patients with irregular breathing motion. This approach also generates 4DCT image data with a reduced total scan time compared to a RCCT scan, without the need for image binning or external respiration signals within the 16 cm scan length. Scan dose can be made comparable to RCCT by optimization of the scan parameters. In addition, it provides the possibility of measuring breathing motion for more than one breathing cycle to assess stability and obtain a more accurate motion PDF, which is currently not feasible with the conventional RCCT approach.

Cost-Effectiveness of Diagnostic Strategies for Suspected Scaphoid Fractures.

PubMed

Yin, Zhong-Gang; Zhang, Jian-Bing; Gong, Ke-Tong

2015-08-01

The aim of this study was to assess the cost effectiveness of multiple competing diagnostic strategies for suspected scaphoid fractures. With published data, the authors created a decision-tree model simulating the diagnosis of suspected scaphoid fractures. Clinical outcomes, costs, and cost effectiveness of immediate computed tomography (CT), day 3 magnetic resonance imaging (MRI), day 3 bone scan, week 2 radiographs alone, week 2 radiographs-CT, week 2 radiographs-MRI, week 2 radiographs-bone scan, and immediate MRI were evaluated. The primary clinical outcome was the detection of scaphoid fractures. The authors adopted societal perspective, including both the costs of healthcare and the cost of lost productivity. The incremental cost-effectiveness ratio (ICER), which expresses the incremental cost per incremental scaphoid fracture detected using a strategy, was calculated to compare these diagnostic strategies. Base case analysis, 1-way sensitivity analyses, and "worst case scenario" and "best case scenario" sensitivity analyses were performed. In the base case, the average cost per scaphoid fracture detected with immediate CT was $2553. The ICER of immediate MRI and day 3 MRI compared with immediate CT was $7483 and $32,000 per scaphoid fracture detected, respectively. The ICER of week 2 radiographs-MRI was around $170,000. Day 3 bone scan, week 2 radiographs alone, week 2 radiographs-CT, and week 2 radiographs-bone scan strategy were dominated or extendedly dominated by MRI strategies. The results were generally robust in multiple sensitivity analyses. Immediate CT and MRI were the most cost-effective strategies for diagnosing suspected scaphoid fractures. Economic and Decision Analyses Level II. See Instructions for Authors for a complete description of levels of evidence.

CT scans for pulmonary surveillance may be overused in lower-grade sarcoma.

PubMed

Miller, Benjamin J; Carmody Soni, Emily E; Reith, John D; Gibbs, C Parker; Scarborough, Mark T

2012-01-01

Chest CT scans are often used to monitor patients after excision of a sarcoma. Although sensitive, CT scans are more expensive than chest radiographs and are associated with possible health risks from a higher radiation dose. We hypothesized that a program based upon limited CT scans in lower-grade sarcoma could be efficacious and less expensive. We retrospectively assigned patients to a high-risk or low-risk hypothetical protocol. Eighty-three low- or intermediate-grade soft tissue sarcomas met our inclusion criteria. Eight patients had pulmonary metastasis. A protocol based on selective CT scans for high-risk patients would have identified seven out of eight lesions. The incremental cost-effectiveness ratio for routine CT scans was $731,400. A program based upon selective CT scans for higher-risk patients is accurate, spares unnecessary radiation to many patients, and is less expensive.

Barium Sulfate

MedlinePlus

... and intestine using x-rays or computed tomography (CAT scan, CT scan; a type of body scan that uses a ... be clearly seen by x-ray examination or CT scan. ... more times before an x-ray examination or CT scan.If you are using a barium sulfate enema, ...

Helical CT scan with 2D and 3D reconstructions and virtual endoscopy versus conventional endoscopy in the assessment of airway disease in neonates, infants and children.

PubMed

Yunus, Mahira

2012-11-01

To study the use of helical computed tomography 2-D and 3-D images, and virtual endoscopy in the evaluation of airway disease in neonates, infants and children and its value in lesion detection, characterisation and extension. Conducted at Al-Noor Hospital, Makkah, Saudi Arabia, from January 1 to June 30, 2006, the study comprised of 40 patients with strider, having various causes of airway obstruction. They were examined by helical CT scan with 2-D and 3-D reconstructions and virtual endoscopy. The level and characterisation of lesions were carried out and results were compared with actual endoscopic findings. Conventional endoscopy was chosen as the gold standard, and the evaluation of endoscopy was done in terms of sensitivity and specificity of the procedure. For statistical purposes, SPSS version 10 was used. All CT methods detected airway stenosis or obstruction. Accuracy was 98% (n=40) for virtual endoscopy, 96% (n=48) for 3-D external rendering, 90% (n=45) for multiplanar reconstructions and 86% (n=43) for axial images. Comparing the results of 3-D internal and external volume rendering images with conventional endoscopy for detection and grading of stenosis were closer than with 2-D minimum intensity multiplanar reconstruction and axial CT slices. Even high-grade stenosis could be evaluated with virtual endoscope through which conventional endoscope cannot be passed. A case of 4-year-old patient with tracheomalacia could not be diagnosed by helical CT scan and virtual bronchoscopy which was diagriosed on conventional endoscopy and needed CT scan in inspiration and expiration. Virtual endoscopy [VE] enabled better assessment of stenosis compared to the reading of 3-D external rendering, 2-D multiplanar reconstruction [MPR] or axial slices. It can replace conventional endoscopy in the assessment of airway disease without any additional risk.

Effective Dose of CT- and Fluoroscopy-Guided Perineural/Epidural Injections of the Lumbar Spine: A Comparative Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmid, Gebhard; Schmitz, Alexander; Borchardt, Dieter

The objective of this study was to compare the effective radiation dose of perineural and epidural injections of the lumbar spine under computed tomography (CT) or fluoroscopic guidance with respect to dose-reduced protocols. We assessed the radiation dose with an Alderson Rando phantom at the lumbar segment L4/5 using 29 thermoluminescence dosimeters. Based on our clinical experience, 4-10 CT scans and 1-min fluoroscopy are appropriate. Effective doses were calculated for CT for a routine lumbar spine protocol and for maximum dose reduction; as well as for fluoroscopy in a continuous and a pulsed mode (3-15 pulses/s). Effective doses under CTmore » guidance were 1.51 mSv for 4 scans and 3.53 mSv for 10 scans using a standard protocol and 0.22 mSv and 0.43 mSv for the low-dose protocol. In continuous mode, the effective doses ranged from 0.43 to 1.25 mSv for 1-3 min of fluoroscopy. Using 1 min of pulsed fluoroscopy, the effective dose was less than 0.1 mSv for 3 pulses/s. A consequent low-dose CT protocol reduces the effective dose compared to a standard lumbar spine protocol by more than 85%. The latter dose might be expected when applying about 1 min of continuous fluoroscopy for guidance. A pulsed mode further reduces the effective dose of fluoroscopy by 80-90%.« less

A comparison between intrastomal 3D ultrasonography, CT scanning and findings at surgery in patients with stomal complaints.

PubMed

Näsvall, P; Wikner, F; Gunnarsson, U; Rutegård, J; Strigård, K

2014-10-01

Since there are no reliable investigative tools for imaging parastomal hernia, new techniques are needed. The aim of this study was to assess the validity of intrastomal three-dimensional ultrasonography (3D) as an alternative to CT scanning for the assessment of stomal complaints. Twenty patients with stomal complaints, indicating surgery, were examined preoperatively with a CT scan in the supine position and 3D intrastomal ultrasonography in the supine and erect positions. Comparison with findings at surgery, considered to be the true state, was made. Both imaging methods, 3D ultrasonography and CT scanning, showed high sensitivity (ultrasound 15/18, CT scan 15/18) and specificity (ultrasound 2/2, CT scan 1/2) when judged by a dedicated radiologist. Corresponding values for interpretation of CT scans in routine clinical practice was for sensitivity 17/18 and for specificity 1/2. 3D ultrasonography has a high validity and is a promising alternative to CT scanning in the supine position to distinguish a bulge from a parastomal hernia.

Repeatability of FDG PET/CT metrics assessed in free breathing and deep inspiration breath hold in lung cancer patients.

PubMed

Nygård, Lotte; Aznar, Marianne C; Fischer, Barbara M; Persson, Gitte F; Christensen, Charlotte B; Andersen, Flemming L; Josipovic, Mirjana; Langer, Seppo W; Kjær, Andreas; Vogelius, Ivan R; Bentzen, Søren M

2018-01-01

We measured the repeatability of FDG PET/CT uptake metrics when acquiring scans in free breathing (FB) conditions compared with deep inspiration breath hold (DIBH) for locally advanced lung cancer. Twenty patients were enrolled in this prospective study. Two FDG PET/CT scans per patient were conducted few days apart and in two breathing conditions (FB and DIBH). This resulted in four scans per patient. Up to four FDG PET avid lesions per patient were contoured. The following FDG metrics were measured in all lesions and in all four scans: Standardized uptake value (SUV) peak , SUV max , SUV mean , metabolic tumor volume (MTV) and total lesion glycolysis (TLG), based on an isocontur of 50% of SUV max . FDG PET avid volumes were delineated by a nuclear medicine physician. The gross tumor volumes (GTV) were contoured on the corresponding CT scans. Nineteen patients were available for analysis. Test-retest standard deviations of FDG uptake metrics in FB and DIBH were: SUV peak FB/DIBH: 16.2%/16.5%; SUV max : 18.2%/22.1%; SUV mean : 18.3%/22.1%; TLG: 32.4%/40.5%. DIBH compared to FB resulted in higher values with mean differences in SUV max of 12.6%, SUV peak 4.4% and SUV mean 11.9%. MTV, TLG and GTV were all significantly smaller on day 1 in DIBH compared to FB. However, the differences between metrics under FB and DIBH were in all cases smaller than 1 SD of the day to day repeatability. FDG acquisition in DIBH does not have a clinically relevant impact on the uptake metrics and does not improve the test-retest repeatability of FDG uptake metrics in lung cancer patients.

Late 124I PET/CT Uptake Measurement-Assessment of Appropriate Examination Protocol in Benign Thyroid Diseases.

PubMed

Freesmeyer, Martin; Gabler, Anja S; Kühnel, Christian; Winkens, Thomas

2017-07-01

This study aimed at investigating the performance of late I PET/CT for radioiodine uptake (RAIU) measurement at 336 hours after administration in patients with benign thyroid diseases requiring radioiodine therapy. Special attention was paid to the comparability of I uptake (I-RAIU) to the clinical standard (I-RAIU, probe measurement). Considering cost aspects, we sought to establish an economically reasonable examination protocol based on scan duration and administered activity. List-mode PET data sets of 40-minute acquisition time were acquired 336 hours after administration of 1 MBq I in 18 patients. Different scan durations were simulated by different reconstruction intervals (RIs) ranging from 5 seconds to 40 minutes, and total thyroid activity was measured. Mean I-RAIU levels of each RI were compared with mean I-RAIU levels (3 MBq). A hypothetical scan duration or hypothetical activity, respectively, was sought by means of a proportion equation, considering that the length of an RI is equitable to a hypothetical activity. After 336 hours, the mean total thyroid activity was 254 ± 7.7 kBq for I and 26.9 ± 8.7 kBq for I. The mean I-RAIU and I-RAIU showed high levels of agreement for RI from 2 minutes to 40 minutes. Reconstruction interval shorter than 2 minutes did not result in sufficient agreement. The present study confirmed the feasibility of late I PET/CT as alternative method for RAIU measurement in patients with benign thyroid diseases; 1 MBq I PET/CT scans as short as 2 minutes resulted in RAIU levels comparable to those of standard I-RAIU. The parameter "appropriate scan-duration activity product" is proposed to enable an economically reasonable examination protocol.

Systematic review on the value of CT scanning in the diagnosis of anastomotic leakage after colorectal surgery.

PubMed

Kornmann, Verena N N; Treskes, Nikki; Hoonhout, Lilian H F; Bollen, Thomas L; van Ramshorst, Bert; Boerma, Djamila

2013-04-01

Timely diagnosis of anastomotic leakage after colorectal surgery and adequate treatment is important to reduce morbidity and mortality. Abdominal computed tomography (CT) scanning is the diagnostic tool of preference, but its value may be questionable in the early postoperative period. The accuracy of CT scanning for the detection of anastomotic leakage and its role in timing of intervention was evaluated. A systematic literature search was performed. Relevant publications were identified from four electronic databases between 1990 and 2011. Inclusion criteria were human studies, studies published in English or Dutch, colorectal surgery with primary anastomosis, and abdominal CT scan with reported outcome for the detection of anastomotic leakage. Exclusion criteria were cohort of fewer than five patients, other gastrointestinal surgery, no anastomosis, and radiological imaging other than CT. Eight studies, including 221 abdominal CT scans, fulfilled the inclusion criteria. Overall, the methodological quality of the studies was poor. The overall sensitivity of CT scanning to diagnose leakage was 0.68 (95 % confidence interval 0.59-0.75) for colonic resection. Data on the sequelae of false-negative CT scanning was not available. There is limited good-quality evidence to determine the value of CT scans in the detection of anastomotic leakage. To prevent delay in diagnosis and appropriate treatment of anastomotic leakage, the relatively low sensitivity of CT scanning must be taken into account.

Demand for CT scans increases during transition from paediatric to adult care: an observational study from 2009 to 2015.

PubMed

Thurley, Pete; Crookdake, Jonathan; Norwood, Mark; Sturrock, Nigel; Fogarty, Andrew W

2018-02-01

Avoiding unnecessary radiation exposure is a clinical priority in children and young adults. We aimed to explore demand for CT scans in a busy general hospital with particular interest in the period of transition from paediatric to adult medical care. We used an observational epidemiological study based in a teaching hospital. Data were obtained on numbers and rates of CT scans from 2009 to 2015. The main outcome was age-stratified rates of receiving a CT scan. There were a total of 262,221 CT scans. There was a large step change in the rate of CT scans over the period of transition from paediatric to adult medical care. Individuals aged 10-15 years experienced 6.7 CT scans per 1000 clinical episodes, while those aged 19-24 years experienced 19.8 CT scans per 1000 clinical episodes (p < 0.001). This difference remained significant for all sensitivity analyses. There is almost a threefold increase in rates of CT scans in the two populations before and after the period of transition from paediatric to adult medical care. While we were unable to adjust for case mix or quantify radiation exposure, paediatricians' diagnostic strategies to minimize radiation exposure may have clinical relevance for adult physicians, and hence enable reductions in ionizing radiation to patients. Advances in knowledge: A large increase in rates of CT scans occurs during adolescence, and considering paediatricians' strategies to minimize radiation exposure may enable reductions to all patients.

Simulation of pseudo-CT images based on deformable image registration of ultrasound images: A proof of concept for transabdominal ultrasound imaging of the prostate during radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meer, Skadi van der; Camps, Saskia M.; Oncology Solutions Department, Philips Research, High Tech Campus 34, Eindhoven 5656 AE

Purpose: Imaging of patient anatomy during treatment is a necessity for position verification and for adaptive radiotherapy based on daily dose recalculation. Ultrasound (US) image guided radiotherapy systems are currently available to collect US images at the simulation stage (US{sub sim}), coregistered with the simulation computed tomography (CT), and during all treatment fractions. The authors hypothesize that a deformation field derived from US-based deformable image registration can be used to create a daily pseudo-CT (CT{sub ps}) image that is more representative of the patients’ geometry during treatment than the CT acquired at simulation stage (CT{sub sim}). Methods: The three prostatemore » patients, considered to evaluate this hypothesis, had coregistered CT and US scans on various days. In particular, two patients had two US–CT datasets each and the third one had five US–CT datasets. Deformation fields were computed between pairs of US images of the same patient and then applied to the corresponding US{sub sim} scan to yield a new deformed CT{sub ps} scan. The original treatment plans were used to recalculate dose distributions in the simulation, deformed and ground truth CT (CT{sub gt}) images to compare dice similarity coefficients, maximum absolute distance, and mean absolute distance on CT delineations and gamma index (γ) evaluations on both the Hounsfield units (HUs) and the dose. Results: In the majority, deformation did improve the results for all three evaluation methods. The change in gamma failure for dose (γ{sub Dose}, 3%, 3 mm) ranged from an improvement of 11.2% in the prostate volume to a deterioration of 1.3% in the prostate and bladder. The change in gamma failure for the CT images (γ{sub CT}, 50 HU, 3 mm) ranged from an improvement of 20.5% in the anus and rectum to a deterioration of 3.2% in the prostate. Conclusions: This new technique may generate CT{sub ps} images that are more representative of the actual patient anatomy than the CT{sub sim} scan.« less

Refixation of Osteochondral Fractures by an Ultrasound-Activated Pin System – An Ovine In Vivo Examination Using CT and Scanning Electron Microscope

PubMed Central

H, Neumann; A.P, Schulz; S, Breer; A, Unger; B, Kienast

2015-01-01

Background: Osteochondral injuries, if not treated appropriately, often lead to severe osteoarthritis of the affected joint. Without refixation of the osteochondral fragment, human cartilage only repairs these defects imperfectly. All existing refixation systems for chondral defects have disadvantages, for instance bad MRI quality in the postoperative follow-up or low anchoring forces. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants a higher anchoring is assumed. Aim of the study was to investigate, if ultrasound-activated pins can provide a secure refixation of osteochondral fractures comparing to conventional screw and conventional, resorbable pin osteosynthesis. CT scans and scanning electron microscopy should proovegood refixation results with no further tissue damage by the melting of the ultrasound-activated pins in comparison to conventional osteosynthesis. Methods: Femoral osteochondral fragments in sheep were refixated with ultrasound-activated pins (SonicPin™), Ethipins® and screws (Asnis™). The quality of the refixated fragments was examined after three month of full weight bearing by CT scans and scanning electron microscopy of the cartilage surface. Results: The CT examination found almost no statistically significant difference in the quality of refixation between the three different implants used. Concerning the CT morphology, ultrasound-activated pins demonstrated at least the same quality in refixation of osteochondral fragments as conventional resorbable pins or screws. The scanning electron microscopy showed no major surface damage by the three implants, especially any postulated cartilage damage induced by the heat of the ultrasound-activated pin. The screws protruded above the cartilage surface, which may affect the opposingtibial surface. Conclusion: Using CT scans and scanning electron microscopy, the SonicPin™, the Ethipin® and screws were at least equivalent in refixation quality of osteochondral fragments. PMID:25674184

TU-F-BRF-03: Effect of Radiation Therapy Planning Scan Registration On the Dose in Lung Cancer Patient CT Scans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cunliffe, A; Contee, C; White, B

Purpose: To characterize the effect of deformable registration of serial computed tomography (CT) scans on the radiation dose calculated from a treatment planning scan. Methods: Eighteen patients who received curative doses (≥60Gy, 2Gy/fraction) of photon radiation therapy for lung cancer treatment were retrospectively identified. For each patient, a diagnostic-quality pre-therapy (4–75 days) CT scan and a treatment planning scan with an associated dose map calculated in Pinnacle were collected. To establish baseline correspondence between scan pairs, a researcher manually identified anatomically corresponding landmark point pairs between the two scans. Pre-therapy scans were co-registered with planning scans (and associated dose maps)more » using the Plastimatch demons and Fraunhofer MEVIS deformable registration algorithms. Landmark points in each pretherapy scan were automatically mapped to the planning scan using the displacement vector field output from both registration algorithms. The absolute difference in planned dose (|ΔD|) between manually and automatically mapped landmark points was calculated. Using regression modeling, |ΔD| was modeled as a function of the distance between manually and automatically matched points (registration error, E), the dose standard deviation (SD-dose) in the eight-pixel neighborhood, and the registration algorithm used. Results: 52–92 landmark point pairs (median: 82) were identified in each patient's scans. Average |ΔD| across patients was 3.66Gy (range: 1.2–7.2Gy). |ΔD| was significantly reduced by 0.53Gy using Plastimatch demons compared with Fraunhofer MEVIS. |ΔD| increased significantly as a function of E (0.39Gy/mm) and SD-dose (2.23Gy/Gy). Conclusion: An average error of <4Gy in radiation dose was introduced when points were mapped between CT scan pairs using deformable registration. Dose differences following registration were significantly increased when the Fraunhofer MEVIS registration algorithm was used, spatial registration errors were larger, and dose gradient was higher (i.e., higher SD-dose). To our knowledge, this is the first study to directly compute dose errors following deformable registration of lung CT scans.« less

Dark-count-less photon-counting x-ray computed tomography system using a YAP-MPPC detector

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Sato, Yuich; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2012-10-01

A high-sensitive X-ray computed tomography (CT) system is useful for decreasing absorbed dose for patients, and a dark-count-less photon-counting CT system was developed. X-ray photons are detected using a YAP(Ce) [cerium-doped yttrium aluminum perovskite] single crystal scintillator and an MPPC (multipixel photon counter). Photocurrents are amplified by a high-speed current-voltage amplifier, and smooth event pulses from an integrator are sent to a high-speed comparator. Then, logical pulses are produced from the comparator and are counted by a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The image contrast of gadolinium medium slightly fell with increase in lower-level voltage (Vl) of the comparator. The dark count rate was 0 cps, and the count rate for the CT was approximately 250 kcps.

The diagnosis of acute appendicitis in a pediatric population: to CT or not to CT.

PubMed

Stephen, Antonia E; Segev, Dorry L; Ryan, Daniel P; Mullins, Mark E; Kim, Samuel H; Schnitzer, Jay J; Doody, Daniel P

2003-03-01

The aim of this study was to determine if focused appendiceal computed tomography with colon contrast (FACT-CC) increases the accuracy of the preoperative diagnosis of acute appendicitis in children. A 5-year retrospective review was conducted of a university hospital database of 283 patients (age 0.8 to 19.3 years; mean, 11.3 years) treated with appendectomy for presumed acute appendicitis. Of the 283 patients in whom appendectomies were performed, 268 were confirmed by pathologic analysis of the specimen to have acute appendicitis for a diagnostic accuracy in our institution of 94.7%. Ninety-six patients (34%) underwent FACT-CC scans as part of their preoperative evaluation. The sensitivity of the computed tomography (CT) scan was 94.6%, and the positive predictive value was 95.6%. In girls older than 10 years, CT imaging was not significantly more accurate in predicting appendicitis than examination alone (93.9% v. 87.5%; P =.46). Preoperative FACT-CC did not increase the accuracy in diagnosing appendicitis when compared with patients diagnosed by history, physical examination and laboratory studies. If there was a strong suspicion of appendicitis, a negative CT scan did not exclude the diagnosis of appendicitis. However, focused appendiceal CT scan is a sensitive test with a high positive predictive value and may be useful in a patient with an atypical history or examination. Copyright 2003, Elsevier Science (USA). All rights reserved.

Prediction value of the Canadian CT head rule and the New Orleans criteria for positive head CT scan and acute neurosurgical procedures in minor head trauma: a multicenter external validation study.

PubMed

Bouida, Wahid; Marghli, Soudani; Souissi, Sami; Ksibi, Hichem; Methammem, Mehdi; Haguiga, Habib; Khedher, Sonia; Boubaker, Hamdi; Beltaief, Kaouthar; Grissa, Mohamed Habib; Trimech, Mohamed Naceur; Kerkeni, Wiem; Chebili, Nawfel; Halila, Imen; Rejeb, Imen; Boukef, Riadh; Rekik, Noureddine; Bouhaja, Bechir; Letaief, Mondher; Nouira, Semir

2013-05-01

The New Orleans Criteria and the Canadian CT Head Rule have been developed to decrease the number of normal computed tomography (CT) results in mild head injury. We compare the performance of both decision rules for identifying patients with intracranial traumatic lesions and those who require an urgent neurosurgical intervention after mild head injury. This was an observational cohort study performed between 2008 and 2011 on patients with mild head injury who were aged 10 years or older. We collected prospectively clinical head CT scan findings and outcome. Primary outcome was need for neurosurgical intervention, defined as either death or craniotomy, or the need of intubation within 15 days of the traumatic event. Secondary outcome was the presence of traumatic lesions on head CT scan. New Orleans Criteria and Canadian CT Head Rule decision rules were compared by using sensitivity specifications and positive and negative predictive value. We enrolled 1,582 patients. Neurosurgical intervention was performed in 34 patients (2.1%) and positive CT findings were demonstrated in 218 patients (13.8%). Sensitivity and specificity for need for neurosurgical intervention were 100% (95% confidence interval [CI] 90% to 100%) and 60% (95% CI 44% to 76%) for the Canadian CT Head Rule and 82% (95% CI 69% to 95%) and 26% (95% CI 24% to 28%) for the New Orleans Criteria. Negative predictive values for the above-mentioned clinical decision rules were 100% and 99% and positive values were 5% and 2%, respectively, for the Canadian CT Head Rule and New Orleans Criteria. Sensitivity and specificity for clinical significant head CT findings were 95% (95% CI 92% to 98%) and 65% (95% CI 62% to 68%) for the Canadian CT Head Rule and 86% (95% CI 81% to 91%) and 28% (95% CI 26% to 30%) for the New Orleans Criteria. A similar trend of results was found in the subgroup of patients with a Glasgow Coma Scale score of 15. For patients with mild head injury, the Canadian CT Head Rule had higher sensitivity than the New Orleans Criteria, with higher negative predictive value. The question of whether the use of the Canadian CT Head Rule would have a greater influence on head CT scan reduction requires confirmation in real clinical practice. Copyright © 2012 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

Ability of calibration phantom to reduce the interscan variability in electron beam computed tomography.

PubMed

Budoff, Matthew J; Mao, Songshou; Lu, Bin; Takasu, Junichiro; Child, Janis; Carson, Sivi; Fisher, Hans

2002-01-01

To test the hypothesis that a calibration phantom would improve interpatient and interscan variability in coronary artery calcium (CAC) studies. We scanned 144 patients twice with or without the calibration phantom and then scanned 93 patients with a single calcific lesion twice and, finally, scanned a cork heart with calcific foci. There were no linear correlations in computed tomography Hounsfield unit (CT HU) and CT HU interscan variation between blood pool and phantom plugs at any slice level in patient groups (p > 0.05). The CT HU interscan variation in phantom plugs (2.11 HU) was less than that of the blood pool (3.47 HU; p < 0.05) and CAC lesion (20.39; p < 0.001). Comparing images with and without a calibration phantom, there was a significant decrease in CT HU as well as an increase in noise and peak values in patient studies and the cork phantom study. The CT HU attenuation variations of the interpatient and interscan blood pool, calibration phantom plug, and cork coronary arteries were not parallel. Therefore, the ability to adjust the CT HU variation of calcific lesions by a calibration phantom is problematic and may worsen the problem.

Reproducibility of 18F-FDG PET uptake measurements in head and neck squamous cell carcinoma on both PET/CT and PET/MR

PubMed Central

Fischer, B M; Aznar, M C; Hansen, A E; Vogelius, I R; Löfgren, J; Andersen, F L; Loft, A; Kjaer, A; Højgaard, L; Specht, L

2015-01-01

Objective: To investigate reproducibility of fluorine-18 fludeoxyglucose (18F-FDG) uptake on 18F-FDG positron emission tomography (PET)/CT and 18F-FDG PET/MR scans in patients with head and neck squamous cell carcinoma (HNSCC). Methods: 30 patients with HNSCC were included in this prospective study. The patients were scanned twice before radiotherapy treatment with both PET/CT and PET/MR. Patients were scanned on the same scanners, 3 days apart and according to the same protocol. Metabolic tumour activity was measured by the maximum and peak standardized uptake value (SUVmax and SUVpeak, respectively), and total lesion glycolysis from the metabolic tumour volume defined from ≥50% SUVmax. Bland–Altman analysis with limits of agreement, coefficient of variation (CV) from the two modalities were performed in order to test the reproducibility. Furthermore, CVs from SUVmax and SUVpeak were compared. The area under the curve from cumulative SUV–volume histograms were measured and tested for reproducibility of the distribution of 18F-FDG uptake. Results: 24 patients had two pre-treatment PET/CT scans and 21 patients had two pre-treatment PET/MR scans available for further analyses. Mean difference for SUVmax, peak and mean was approximately 4% for PET/CT and 3% for PET/MR, with 95% limits of agreement less than ±20%. CV was small (5–7%) for both modalities. There was no significant difference in CVs between PET/CT and PET/MR (p = 0.31). SUVmax was not more reproducible than SUVpeak (p = 0.09). Conclusion: 18F-FDG uptake in PET/CT and PET/MR is highly reproducible and we found no difference in reproducibility between PET/CT and PET/MR. Advances in knowledge: This is the first report to test reproducibility of PET/CT and PET/MR. PMID:25634069

New prospective 4D-CT for mitigating the effects of irregular respiratory motion

NASA Astrophysics Data System (ADS)

Pan, Tinsu; Martin, Rachael M.; Luo, Dershan

2017-08-01

Artifact caused by irregular respiration is a major source of error in 4D-CT imaging. We propose a new prospective 4D-CT to mitigate this source of error without new hardware, software or off-line data-processing on the GE CT scanner. We utilize the cine CT scan in the design of the new prospective 4D-CT. The cine CT scan at each position can be stopped by the operator when an irregular respiration occurs, and resumed when the respiration becomes regular. This process can be repeated at one or multiple scan positions. After the scan, a retrospective reconstruction is initiated on the CT console to reconstruct only the images corresponding to the regular respiratory cycles. The end result is a 4D-CT free of irregular respiration. To prove feasibility, we conducted a phantom and six patient studies. The artifacts associated with the irregular respiratory cycles could be removed from both the phantom and patient studies. A new prospective 4D-CT scanning and processing technique to mitigate the impact of irregular respiration in 4D-CT has been demonstrated. This technique can save radiation dose because the repeat scans are only at the scan positions where an irregular respiration occurs. Current practice is to repeat the scans at all positions. There is no cost to apply this technique because it is applicable on the GE CT scanner without new hardware, software or off-line data-processing.

Is triple contrast computed tomographic scanning useful in the selective management of stab wounds to the back?

PubMed

McAllister, E; Perez, M; Albrink, M H; Olsen, S M; Rosemurgy, A S

1994-09-01

We devised a protocol to prospectively manage stab wounds to the back with the hypothesis that the triple contrast computed tomographic (CT) scan is an effective means of detecting occult injury in these patients. All wounds to the back in hemodynamically stable adults were locally explored. All patients with muscular fascial penetration underwent triple contrast CT scanning utilizing oral, rectal, and IV contrast. Patients did not undergo surgical exploration if their CT scan was interpreted as negative or if the CT scan demonstrated injuries not requiring surgical intervention. Fifty-three patients were entered into the protocol. The time to complete the triple contrast CT scan ranged from 3 to 6 hours at a cost of $1050 for each scan. In 51 patients (96%), the CT scan either had negative findings (n = 31) or showed injuries not requiring exploration (n = 20). These patients did well with nonsurgical management. Two CT scans documented significant injury and led to surgical exploration and therapeutic celiotomies. Although triple contrast CT scanning was able to detect occult injury in patients with stab wounds to the back it did so at considerable cost and the results rarely altered clinical care. Therefore, its routine use in these patients is not recommended.

Efficient digitalization method for dental restorations using micro-CT data

NASA Astrophysics Data System (ADS)

Kim, Changhwan; Baek, Seung Hoon; Lee, Taewon; Go, Jonggun; Kim, Sun Young; Cho, Seungryong

2017-03-01

The objective of this study was to demonstrate the feasibility of using micro-CT scan of dental impressions for fabricating dental restorations and to compare the dimensional accuracy of dental models generated from various methods. The key idea of the proposed protocol is that dental impression of patients can be accurately digitized by micro-CT scan and that one can make digital cast model from micro-CT data directly. As air regions of the micro-CT scan data of dental impression are equivalent to the real teeth and surrounding structures, one can segment the air regions and fabricate digital cast model in the STL format out of them. The proposed method was validated by a phantom study using a typodont with prepared teeth. Actual measurement and deviation map analysis were performed after acquiring digital cast models for each restoration methods. Comparisons of the milled restorations were also performed by placing them on the prepared teeth of typodont. The results demonstrated that an efficient fabrication of precise dental restoration is achievable by use of the proposed method.

Micro-CT Sections and Histological Sections of Mouse Skull Defects Implanted with Cartilage Grown in a Rotating Bioreactor

NASA Astrophysics Data System (ADS)

Duke, P. J.; Montufar-Solis, D.; Nguyen, H. C.; Cody, D. D.

2008-06-01

Using cartilage to replace/repair bone is advantageous as no scaffolding is required to form the implant which disappears as bone is formed during the endochondral process. Previously, we demonstrated that cartilage spheroids, grown in a rotating bioreactor, (Synthecon, Inc.) and implanted into a 2 mm skull defect, contributed to healing of the defect. In this report, skulls with or without implants were subjected to microCT scans, and sections from these scans were compared to histological sections of the defect region of demineralized skulls from the same experiment. The area of the defect staining for bone in histological sections of demineralized skulls was the same region shown as mineralized in CT sections. Defects without implants were shown in serial CT sections and histological sections, to be incompletely healed. This study demonstrates that microCT scans are an important corollary to histological studies evaluating the use of implants in healing of bony defects. Supported in part by NIH/NIDCR Training Grant T35 DE07252 and by Cancer Center Support Grant (CA-16672).

A combined pulmonary-radiology workshop for visual evaluation of COPD: study design, chest CT findings and concordance with quantitative evaluation.

PubMed

Barr, R Graham; Berkowitz, Eugene A; Bigazzi, Francesca; Bode, Frederick; Bon, Jessica; Bowler, Russell P; Chiles, Caroline; Crapo, James D; Criner, Gerard J; Curtis, Jeffrey L; Dass, Chandra; Dirksen, Asger; Dransfield, Mark T; Edula, Goutham; Erikkson, Leif; Friedlander, Adam; Galperin-Aizenberg, Maya; Gefter, Warren B; Gierada, David S; Grenier, Philippe A; Goldin, Jonathan; Han, MeiLan K; Hanania, Nicola A; Hansel, Nadia N; Jacobson, Francine L; Kauczor, Hans-Ulrich; Kinnula, Vuokko L; Lipson, David A; Lynch, David A; MacNee, William; Make, Barry J; Mamary, A James; Mann, Howard; Marchetti, Nathaniel; Mascalchi, Mario; McLennan, Geoffrey; Murphy, James R; Naidich, David; Nath, Hrudaya; Newell, John D; Pistolesi, Massimo; Regan, Elizabeth A; Reilly, John J; Sandhaus, Robert; Schroeder, Joyce D; Sciurba, Frank; Shaker, Saher; Sharafkhaneh, Amir; Silverman, Edwin K; Steiner, Robert M; Strange, Charlton; Sverzellati, Nicola; Tashjian, Joseph H; van Beek, Edwin J R; Washington, Lacey; Washko, George R; Westney, Gloria; Wood, Susan A; Woodruff, Prescott G

2012-04-01

The purposes of this study were: to describe chest CT findings in normal non-smoking controls and cigarette smokers with and without COPD; to compare the prevalence of CT abnormalities with severity of COPD; and to evaluate concordance between visual and quantitative chest CT (QCT) scoring. Volumetric inspiratory and expiratory CT scans of 294 subjects, including normal non-smokers, smokers without COPD, and smokers with GOLD Stage I-IV COPD, were scored at a multi-reader workshop using a standardized worksheet. There were 58 observers (33 pulmonologists, 25 radiologists); each scan was scored by 9-11 observers. Interobserver agreement was calculated using kappa statistic. Median score of visual observations was compared with QCT measurements. Interobserver agreement was moderate for the presence or absence of emphysema and for the presence of panlobular emphysema; fair for the presence of centrilobular, paraseptal, and bullous emphysema subtypes and for the presence of bronchial wall thickening; and poor for gas trapping, centrilobular nodularity, mosaic attenuation, and bronchial dilation. Agreement was similar for radiologists and pulmonologists. The prevalence on CT readings of most abnormalities (e.g. emphysema, bronchial wall thickening, mosaic attenuation, expiratory gas trapping) increased significantly with greater COPD severity, while the prevalence of centrilobular nodularity decreased. Concordances between visual scoring and quantitative scoring of emphysema, gas trapping and airway wall thickening were 75%, 87% and 65%, respectively. Despite substantial inter-observer variation, visual assessment of chest CT scans in cigarette smokers provides information regarding lung disease severity; visual scoring may be complementary to quantitative evaluation.

Radiation dose calculations for CT scans with tube current modulation using the approach to equilibrium function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu

2014-11-01

Purpose: The approach to equilibrium function has been used previously to calculate the radiation dose to a shift-invariant medium undergoing CT scans with constant tube current [Li, Zhang, and Liu, Med. Phys. 39, 5347–5352 (2012)]. The authors have adapted this method to CT scans with tube current modulation (TCM). Methods: For a scan with variable tube current, the scan range was divided into multiple subscan ranges, each with a nearly constant tube current. Then the dose calculation algorithm presented previously was applied. For a clinical CT scan series that presented tube current per slice, the authors adopted an efficient approachmore » that computed the longitudinal dose distribution for one scan length equal to the slice thickness, which center was at z = 0. The cumulative dose at a specific point was a summation of the contributions from all slices and the overscan. Results: The dose calculations performed for a total of four constant and variable tube current distributions agreed with the published results of Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)]. For an abdomen/pelvis scan of an anthropomorphic phantom (model ATOM 701-B, CIRS, Inc., VA) on a GE Lightspeed Pro 16 scanner with 120 kV, N × T = 20 mm, pitch = 1.375, z axis current modulation (auto mA), and angular current modulation (smart mA), dose measurements were performed using two lines of optically stimulated luminescence dosimeters, one of which was placed near the phantom center and the other on the surface. Dose calculations were performed on the central and peripheral axes of a cylinder containing water, whose cross-sectional mass was about equal to that of the ATOM phantom in its abdominal region, and the results agreed with the measurements within 28.4%. Conclusions: The described method provides an effective approach that takes into account subject size, scan length, and constant or variable tube current to evaluate CT dose to a shift-invariant medium. For a clinical CT scan, dose calculations may be performed with a water-containing cylinder whose cross-sectional mass is equal to that of the subject. This method has the potential to substantially improve evaluations of patient dose from clinical CT scans, compared to CTDI{sub vol}, size-specific dose estimate (SSDE), or the dose evaluated for a TCM scan with a constant tube current equal to the average tube current of the TCM scan.« less

[Practice guideline 'Management of patients with mild traumatic head/brain injury' in the Netherlands].

PubMed

van den Brand, Crispijn L; Rambach, A H J H Annelijn; Postma, Roelie; van de Craats, Victoria L; Lengers, Frank; Bénit, Christa P; Verbree, Femke C; Jellema, Korné

2014-01-01

To evaluate the effect of the revised practice guideline 'Management of patients with mild traumatic head/brain injury' (MHI) in the Netherlands using the number of CT scans of the cerebrum, number of hospital admissions, and the number of intracranial traumatic findings on CT scan. Retrospective before-and-after study. A structured chart review over the 3-month period considerable time after implementation of the MHI guideline (study period) was compared with the 3-month-period before its introduction (control period). Both children and adults were included. Primary outcome measures were the percentage of hospital admissions and percentage of cerebrum CT scans in patients with MHI. Secondary outcome measures were traumatic findings on CT scan, neurosurgical intervention and adherence to the guideline. During the study and control periods, respectively 1063 and 1026 patients with MHI attended the emergency department of the study centre. During the study period a CT scan was carried out in 34.2% of patients, significantly more than in the control period 18.8%; p < 0.01). The percentage of admissions also increased from 13.8% to 18.2% (p = 0.01). The differences between the two periods were mainly in adults and in children aged 6 and older. There was no significant change in traumatic intracranial findings or neurosurgical interventions. Adherence to the guideline in regard to hospitalization (81.7% guideline adherence) and CT brain imaging (88.3% guideline adherence) was reasonably high. After introduction of the current MHI guideline in the Netherlands, percentages of both hospitalization and CT of cerebrum have increased significantly. It was expected that the guideline would result in decreases of this percentages. This increase does not seem to be related to more or serious head/brain injury.

Dual-time point scanning of integrated FDG PET/CT for the evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT.

PubMed

Kasai, Takami; Motoori, Ken; Horikoshi, Takuro; Uchiyama, Katsuhiro; Yasufuku, Kazuhiro; Takiguchi, Yuichi; Takahashi, Fumiaki; Kuniyasu, Yoshio; Ito, Hisao

2010-08-01

To evaluate whether dual-time point scanning with integrated fluorine-18 fluorodeoxyglucose ((18)F-FDG) positron emission tomography and computed tomography (PET/CT) is useful for evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT. PET/CT data and pathological findings of 560 nodal stations in 129 patients with pathologically proven non-small cell lung cancer diagnosed as operable by contrast-enhanced CT were reviewed retrospectively. Standardized uptake values (SUVs) on early scans (SUVe) 1h, and on delayed scans (SUVd) 2h after FDG injection of each nodal station were measured. Retention index (RI) (%) was calculated by subtracting SUVe from SUVd and dividing by SUVe. Logistic regression analysis was performed with seven kinds of models, consisting of (1) SUVe, (2) SUVd, (3) RI, (4) SUVe and SUVd, (5) SUVe and RI, (6) SUVd and RI, and (7) SUVe, SUVd and RI. The seven derived models were compared by receiver-operating characteristic (ROC) analysis. k-Fold cross-validation was performed with k values of 5 and 10. p<0.05 was considered statistically significant. Model (1) including the term of SUVe showed the largest area under the ROC curve among the seven models. The cut-off probability of metastasis of 3.5% with SUVe of 2.5 revealed a sensitivity of 78% and a specificity of 81% on ROC analysis, and approximately 60% and 80% on k-fold cross-validation. Single scanning of PET/CT is sufficiently useful for evaluating mediastinal and hilar nodes for metastasis. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

Dual energy exposure control (DEEC) for computed tomography: algorithm and simulation study.

PubMed

Stenner, Philip; Kachelriess, Marc

2008-11-01

DECT means acquiring the same object at two different energies, respectively two different tube voltages U1 and U2. The raw data q1 and q2 undergo a decomposition process of type p = p(q1,q2). The raw data p are reconstructed to obtain monochromatic images of the attenuation mu, of the object density rho, or of a specific material distribution. Recent advances in DECT focus on noise reduction techniques [S. Richard and J. H. Siewerdsen, Med. Phys. 35(2), 586-600 (2008)] and enable high performance DECT such as lung nodule detection [Shkumat et al., Med. Phys. 35(2), 629-632 (2008)]. Given p and a raw data-based projection-wise patient dose estimation D(alpha) the authors determine the optimal tube current curves I1(alpha) and I2(alpha), with alpha being the view angle, which minimizes image noise for a given patient dose level. DEEC can perform online; I1(alpha) and I2(alpha) can be determined during the scan. Simulation studies using semianthropomorphic phantom data were carried out. In particular, functions p that generate mu-images and density images were evaluated. Image quality was compared to standard scans at U0=120 kV (clinical CT) and U0=45 kV (micro-CT) that were taken at the same dose level (D0=D1 + D2) and identical spatial resolution. Appropriate choice of p(q1, q2) allows to obtain mu-images that show fewer artifacts and yield image noise levels comparable to the noise of the standard scan. The authors compared the standard scan to mu-images at 70 keV, which is the effective energy used in clinical CT, and found optimal results with mu-images at 25 keV for micro-CT. Nonoptimal choice of the decomposition function will, however, significantly increase image noise. In particular mu-images at 511 keV, as needed for PET/CT attenuation correction, exhibit more than twice as much image noise as the standard scan. With DEEC, which guarantees best dose usage possible, monochromatic images are generated with only slightly increased noise levels at the same dose compared to a standard scan. The benefit of significantly decreased artifacts appears to allow using DEEC-generated monochromatic images in daily routine. Furthermore, DEEC is not restricted to DECT and the inherent tube current modulation algorithm may also be applied to single energy CT.

Dual energy exposure control (DEEC) for computed tomography: Algorithm and simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stenner, Philip; Kachelriess, Marc

2008-11-15

DECT means acquiring the same object at two different energies, respectively two different tube voltages U{sub 1} and U{sub 2}. The raw data q{sub 1} and q{sub 2} undergo a decomposition process of type p=p(q{sub 1},q{sub 2}). The raw data p are reconstructed to obtain monochromatic images of the attenuation {mu}, of the object density {rho}, or of a specific material distribution. Recent advances in DECT focus on noise reduction techniques [S. Richard and J. H. Siewerdsen, Med. Phys. 35(2), 586-600 (2008)] and enable high performance DECT such as lung nodule detection [Shkumat et al., Med. Phys. 35(2), 629-632 (2008)].more » Given p and a raw data-based projection-wise patient dose estimation D({alpha}) the authors determine the optimal tube current curves I{sub 1}({alpha}) and I{sub 2}({alpha}), with {alpha} being the view angle, which minimizes image noise for a given patient dose level. DEEC can perform online; I{sub 1}({alpha}) and I{sub 2}({alpha}) can be determined during the scan. Simulation studies using semianthropomorphic phantom data were carried out. In particular, functions p that generate {mu}-images and density images were evaluated. Image quality was compared to standard scans at U{sub 0}=120 kV (clinical CT) and U{sub 0}=45 kV (micro-CT) that were taken at the same dose level (D{sub 0}=D{sub 1}+D{sub 2}) and identical spatial resolution. Appropriate choice of p(q{sub 1},q{sub 2}) allows to obtain {mu}-images that show fewer artifacts and yield image noise levels comparable to the noise of the standard scan. The authors compared the standard scan to {mu}-images at 70 keV, which is the effective energy used in clinical CT, and found optimal results with {mu}-images at 25 keV for micro-CT. Nonoptimal choice of the decomposition function will, however, significantly increase image noise. In particular {mu}-images at 511 keV, as needed for PET/CT attenuation correction, exhibit more than twice as much image noise as the standard scan. With DEEC, which guarantees best dose usage possible, monochromatic images are generated with only slightly increased noise levels at the same dose compared to a standard scan. The benefit of significantly decreased artifacts appears to allow using DEEC-generated monochromatic images in daily routine. Furthermore, DEEC is not restricted to DECT and the inherent tube current modulation algorithm may also be applied to single energy CT.« less

Quantitative Image Quality and Histogram-Based Evaluations of an Iterative Reconstruction Algorithm at Low-to-Ultralow Radiation Dose Levels: A Phantom Study in Chest CT

PubMed Central

Lee, Ki Baek

2018-01-01

Objective To describe the quantitative image quality and histogram-based evaluation of an iterative reconstruction (IR) algorithm in chest computed tomography (CT) scans at low-to-ultralow CT radiation dose levels. Materials and Methods In an adult anthropomorphic phantom, chest CT scans were performed with 128-section dual-source CT at 70, 80, 100, 120, and 140 kVp, and the reference (3.4 mGy in volume CT Dose Index [CTDIvol]), 30%-, 60%-, and 90%-reduced radiation dose levels (2.4, 1.4, and 0.3 mGy). The CT images were reconstructed by using filtered back projection (FBP) algorithms and IR algorithm with strengths 1, 3, and 5. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were statistically compared between different dose levels, tube voltages, and reconstruction algorithms. Moreover, histograms of subtraction images before and after standardization in x- and y-axes were visually compared. Results Compared with FBP images, IR images with strengths 1, 3, and 5 demonstrated image noise reduction up to 49.1%, SNR increase up to 100.7%, and CNR increase up to 67.3%. Noteworthy image quality degradations on IR images including a 184.9% increase in image noise, 63.0% decrease in SNR, and 51.3% decrease in CNR, and were shown between 60% and 90% reduced levels of radiation dose (p < 0.0001). Subtraction histograms between FBP and IR images showed progressively increased dispersion with increased IR strength and increased dose reduction. After standardization, the histograms appeared deviated and ragged between FBP images and IR images with strength 3 or 5, but almost normally-distributed between FBP images and IR images with strength 1. Conclusion The IR algorithm may be used to save radiation doses without substantial image quality degradation in chest CT scanning of the adult anthropomorphic phantom, down to approximately 1.4 mGy in CTDIvol (60% reduced dose). PMID:29354008

Radiation exposure from Chest CT: Issues and Strategies

PubMed Central

Maher, Michael M.; Rizzo, Stefania; Kanarek, David; Shephard, Jo-Anne O.

2004-01-01

Concerns have been raised over alleged overuse of CT scanning and inappropriate selection of scanning methods, all of which expose patients to unnecessary radiation. Thus, it is important to identify clinical situations in which techniques with lower radiation dose such as plain radiography or no radiation such as MRI and occasionally ultrasonography can be chosen over CT scanning. This article proposes the arguments for radiation dose reduction in CT scanning of the chest and discusses recommended practices and studies that address means of reducing radiation exposure associated with CT scanning of the chest. PMID:15082885

Radiation dose in 320-slice multidetector cardiac CT: a single center experience of evolving dose minimization.

PubMed

Tung, Matthew K; Cameron, James D; Casan, Joshua M; Crossett, Marcus; Troupis, John M; Meredith, Ian T; Seneviratne, Sujith K

2013-01-01

Minimization of radiation exposure remains an important subject that occurs in parallel with advances in scanner technology. We report our experience of evolving radiation dose and its determinants after the introduction of 320-multidetector row cardiac CT within a single tertiary cardiology referral service. Four cohorts of consecutive patients (total 525 scans), who underwent cardiac CT at defined time points as early as 2008, are described. These include a cohort just after scanner installation, after 2 upgrades of the operating system, and after introduction of an adaptive iterative image reconstruction algorithm. The proportions of nondiagnostic coronary artery segments and studies with nondiagnostic segments were compared between cohorts. Significant reductions were observed in median radiation doses in all cohorts compared with the initial cohort (P < .001). Median dose-length product fell from 944 mGy · cm (interquartile range [IQR], 567.3-1426.5 mGy · cm) to 156 mGy · cm (IQR, 99.2-265.0 mGy · cm). Although the proportion of prospectively triggered scans has increased, reductions in radiation dose have occurred independently of distribution of scan formats. In multiple regression that combined all groups, determinants of dose-length product were tube output, the number of cardiac cycles scanned, tube voltage, scan length, scan format, body mass index, phase width, and heart rate (adjusted R(2) = 0.85, P < .001). The proportion of nondiagnostic coronary artery segments was slightly increased in group 4 (2.9%; P < .01). While maintaining diagnostic quality in 320-multidetector row cardiac CT, the radiation dose has decreased substantially because of a combination of dose-reduction protocols and technical improvements. Continued minimization of radiation dose will increase the potential for cardiac CT to expand as a cardiac imaging modality. Copyright © 2013 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

A rigid motion correction method for helical computed tomography (CT)

NASA Astrophysics Data System (ADS)

Kim, J.-H.; Nuyts, J.; Kyme, A.; Kuncic, Z.; Fulton, R.

2015-03-01

We propose a method to compensate for six degree-of-freedom rigid motion in helical CT of the head. The method is demonstrated in simulations and in helical scans performed on a 16-slice CT scanner. Scans of a Hoffman brain phantom were acquired while an optical motion tracking system recorded the motion of the bed and the phantom. Motion correction was performed by restoring projection consistency using data from the motion tracking system, and reconstructing with an iterative fully 3D algorithm. Motion correction accuracy was evaluated by comparing reconstructed images with a stationary reference scan. We also investigated the effects on accuracy of tracker sampling rate, measurement jitter, interpolation of tracker measurements, and the synchronization of motion data and CT projections. After optimization of these aspects, motion corrected images corresponded remarkably closely to images of the stationary phantom with correlation and similarity coefficients both above 0.9. We performed a simulation study using volunteer head motion and found similarly that our method is capable of compensating effectively for realistic human head movements. To the best of our knowledge, this is the first practical demonstration of generalized rigid motion correction in helical CT. Its clinical value, which we have yet to explore, may be significant. For example it could reduce the necessity for repeat scans and resource-intensive anesthetic and sedation procedures in patient groups prone to motion, such as young children. It is not only applicable to dedicated CT imaging, but also to hybrid PET/CT and SPECT/CT, where it could also ensure an accurate CT image for lesion localization and attenuation correction of the functional image data.

Influence of hypodermic needle dimensions on subcutaneous injection delivery--a pig study of injection deposition evaluated by CT scanning, histology, and backflow.

PubMed

Juul, Kezia Ann Praestmark; Bengtsson, Henrik; Eyving, Bente; Kildegaard, Jonas; Lav, Steffen; Poulsen, Mette; Serup, Jørgen; Stallknecht, Bente

2012-11-01

Thinner and shorter needles for subcutaneous administration are continuously developed. Previous studies have shown that a thinner needle causes fewer occurrences of painful needle insertions and that a shorter needle decreases the occurrence of painful intramuscular injections. However, little is known about local drug delivery in relation to needle length and thickness. This study aimed to compare deposition depth and backflow from three hypodermic needles of 3 mm 34G (0.19 mm), 5 mm 32G (0.23 mm), and 8 mm 30G (0.30 mm) in length and thickness. Ex vivo experiments were carried out on pigs, in neck tissue comparable to human skin at typical injection sites. Six pigs were included and a total of 72 randomized injections were given, i.e. 24 subcutaneous injections given with each needle type. Accordingly, 400 μL was injected including 70% NovoRapid(®) (Novo Nordisk A/S, Bagsvμrd, Denmark) and 30% Xenetix(®) (Guerbet, Villepinte, France) contrast including 1 mg/mL Alcian blue. Surgical biopsies of injection sites were sampled and computer topographic (CT)-scanned in 3D to assess deposition and local distribution. Biopsies were prepared and stained to evaluate deposition in comparison to the CT-scanning findings. The backflow of each injection was collected with filter paper. The blue stains of filter paper were digitized and volume estimated by software calculation vs. control staining. CT-scanning (n = 57) and histology (n = 10) showed that, regardless of injection depth, the bulk of the injection was in the subcutaneous tissue and did not propagate from subcutis into dermis. With the 8 mm 30G needle all injections apart from one intramuscular injection were located in the subcutaneous layer. The volume depositions peaked in 4-5 mm depth for the 3 mm 34G needle, in 5-6 mm depth for the 5 mm 32G needle, and in 9-10 mm depth for the 8 mm 30G needle. In general, injection depositions evaluated by histology and CT-scans compared well for the individual biopsies. The amount of backflow (n = 69) from the 3 mm 34G needle was smaller (P < 0.05) as compared to the 5 mm 32G and the 8 mm 30G needles. Analysis showed a correlation between backflow and the needle's outer dimension with the needle diameter being the pivotal parameter. Furthermore, CT-scanning and histology confirmed that local propagation of the injection and final distribution followed a route of less mechanical resistance as determined by connective tissue barriers preset in the site of injection. Needles as short as 3 mm efficiently delivered injections into the subcutaneous target. The amount of backflow was smaller with thinner needles. Local distribution was variable and determined by mechanical barriers preset in the tissue. CT-scans and histology were concordant. © 2012 John Wiley & Sons A/S.

Dual-energy CT and ceramic or titanium prostheses material reduce CT artifacts and provide superior image quality of total knee arthroplasty.

PubMed

Kasparek, Maximilian F; Töpker, Michael; Lazar, Mathias; Weber, Michael; Kasparek, Michael; Mang, Thomas; Apfaltrer, Paul; Kubista, Bernd; Windhager, Reinhard; Ringl, Helmut

2018-06-07

To evaluate the influence of different scan parameters for single-energy CT and dual-energy CT, as well as the impact of different material used in a TKA prosthesis on image quality and the extent of metal artifacts. Eight pairs of TKA prostheses from different vendors were examined in a phantom set-up. Each pair consisted of a conventional CoCr prosthesis and the corresponding anti-allergic prosthesis (full titanium, ceramic, or ceramic-coated) from the same vendor. Nine different (seven dual-energy CT and two single-energy CT) scan protocols with different characteristics were used to determine the most suitable CT protocol for TKA imaging. Quantitative image analysis included assessment of blooming artifacts (metal implants appear thicker on CT than they are, given as virtual growth in mm in this paper) and streak artifacts (thick dark lines around metal). Qualitative image analysis was used to investigate the bone-prosthesis interface. The full titanium prosthesis and full ceramic knee showed significantly fewer blooming artifacts compared to the standard CoCr prosthesis (mean virtual growth 0.6-2.2 mm compared to 2.9-4.6 mm, p < 0.001). Dual-energy CT protocols showed less blooming (range 3.3-3.8 mm) compared to single-energy protocols (4.6-5.5 mm). The full titanium and full ceramic prostheses showed significantly fewer streak artifacts (mean standard deviation 77-86 Hounsfield unit (HU)) compared to the standard CoCr prosthesis (277-334 HU, p < 0.001). All dual-energy CT protocols had fewer metal streak artifacts (215-296 HU compared to single-energy CT protocols (392-497 HU)). Full titanium and ceramic prostheses were ranked superior with regard to the image quality at the bone/prosthesis interface compared to a standard CoCr prosthesis, and all dual-energy CT protocols were ranked better than single-energy protocols. Dual-energy CT and ceramic or titanium prostheses reduce CT artifacts and provide superior image quality of total knee arthroplasty at the bone/prosthesis interface. These findings support the use of dual-energy CT as a solid imaging base for clinical decision-making and the use of full-titanium or ceramic prostheses to allow for better CT visualization of the bone-prosthesis interface.

Optimizing Radiation Doses for Computed Tomography Across Institutions: Dose Auditing and Best Practices.

PubMed

Demb, Joshua; Chu, Philip; Nelson, Thomas; Hall, David; Seibert, Anthony; Lamba, Ramit; Boone, John; Krishnam, Mayil; Cagnon, Christopher; Bostani, Maryam; Gould, Robert; Miglioretti, Diana; Smith-Bindman, Rebecca

2017-06-01

Radiation doses for computed tomography (CT) vary substantially across institutions. To assess the impact of institutional-level audit and collaborative efforts to share best practices on CT radiation doses across 5 University of California (UC) medical centers. In this before/after interventional study, we prospectively collected radiation dose metrics on all diagnostic CT examinations performed between October 1, 2013, and December 31, 2014, at 5 medical centers. Using data from January to March (baseline), we created audit reports detailing the distribution of radiation dose metrics for chest, abdomen, and head CT scans. In April, we shared reports with the medical centers and invited radiology professionals from the centers to a 1.5-day in-person meeting to review reports and share best practices. We calculated changes in mean effective dose 12 weeks before and after the audits and meeting, excluding a 12-week implementation period when medical centers could make changes. We compared proportions of examinations exceeding previously published benchmarks at baseline and following the audit and meeting, and calculated changes in proportion of examinations exceeding benchmarks. Of 158 274 diagnostic CT scans performed in the study period, 29 594 CT scans were performed in the 3 months before and 32 839 CT scans were performed 12 to 24 weeks after the audit and meeting. Reductions in mean effective dose were considerable for chest and abdomen. Mean effective dose for chest CT decreased from 13.2 to 10.7 mSv (18.9% reduction; 95% CI, 18.0%-19.8%). Reductions at individual medical centers ranged from 3.8% to 23.5%. The mean effective dose for abdominal CT decreased from 20.0 to 15.0 mSv (25.0% reduction; 95% CI, 24.3%-25.8%). Reductions at individual medical centers ranged from 10.8% to 34.7%. The number of CT scans that had an effective dose measurement that exceeded benchmarks was reduced considerably by 48% and 54% for chest and abdomen, respectively. After the audit and meeting, head CT doses varied less, although some institutions increased and some decreased mean head CT doses and the proportion above benchmarks. Reviewing institutional doses and sharing dose-optimization best practices resulted in lower radiation doses for chest and abdominal CT and more consistent doses for head CT.

MDCT of acute pancreatitis: Intraindividual comparison of single-phase versus dual-phase MDCT for initial assessment of acute pancreatitis using different CT scoring systems.

PubMed

Avanesov, Maxim; Weinrich, Julius M; Kraus, Thomas; Derlin, Thorsten; Adam, Gerhard; Yamamura, Jin; Karul, Murat

2016-11-01

The purpose of the retrospective study was to evaluate the additional value of dual-phase multidetector computed tomography (MDCT) protocols over a single-phase protocol on initial MDCT in patients with acute pancreatitis using three CT-based pancreatitis severity scores with regard to radiation dose. In this retrospective, IRB approved study MDCT was performed in 102 consecutive patients (73 males; 55years, IQR48-64) with acute pancreatitis. Inclusion criteria were CT findings of interstitial edematous pancreatitis (IP) or necrotizing pancreatitis (NP) and a contrast-enhanced dual-phase (arterial phase and portal-venous phase) abdominal CT performed at ≥72h after onset of symptoms. The severity of pancreatic and extrapancreatic changes was independently assessed by 2 observers using 3 validated CT-based scoring systems (CTSI, mCTSI, EPIC). All scores were applied to arterial phase and portal venous phase scans and compared to score results of portal venous phase scans, assessed ≥14days after initial evaluation. For effective dose estimation, volume CT dose index (CTDIvol) and dose length product (DLP) were recorded in all examinations. In neither of the CT severity scores a significant difference was observed after application of a dual-phase protocol compared with a single-phase protocol (IP: CTSI: 2.7 vs. 2.5, p=0.25; mCTSI: 4.0 vs. 4.0, p=0.10; EPIC: 2.0 vs. 2.0, p=0.41; NP: CTSI: 8.0 vs. 7.0, p=0.64; mCTSI: 8.0 vs. 8.0, p=0.10; EPIC: 3.0 vs. 3.0, p=0.06). The application of a single-phase CT protocol was associated with a median effective dose reduction of 36% (mean dose reduction 31%) compared to a dual-phase CT scan. An initial dual-phase abdominal CT after ≥72h after onset of symptoms of acute pancreatitis was not superior to a single-phase protocol for evaluation of the severity of pancreatic and extrapancreatic changes. However, the effective radiation dose may be reduced by 36% using a single-phase protocol. Copyright © 2016. Published by Elsevier Ireland Ltd.

CT Scanning in Identification of Sheep Cystic Echinococcosis.

PubMed

Mao, Rui; Qi, Hongzhi; Pei, Lei; Hao, Jie; Dong, Jian; Jiang, Tao; Ainiwaer, Abudula; Shang, Ge; Xu, Lin; Shou, Xi; Zhang, Songan; Wu, Ge; Lu, Pengfei; Bao, Yongxing; Li, Haitao

2017-01-01

We aim to determine the efficiency of CT in identification of cystic echinococcosis in sheep. Fifty-three sheep with liver cysts confirmed by ultrasonography were subject to CT scan to evaluate the number, size, and type of the cysts in liver and lung, confirmed using necropsy. The correlation of numbers between liver cysts and lung cysts was calculated using Pearson analysis. Necropsy indicated a 98% consensus on size, location, number, and activity compared with CT scan. The viable cysts were 53.1% and 50.6% in the liver and lung, respectively. Among the cysts in liver, 35.5%, 9.5%, 5.7%, 10.2%, and 39.1% were Types CE1, CE2, CE3, CE4, and CE5, respectively. The cysts in the lungs, 17.4%, 26.9%, 12.1%, 11.6%, and 32.1%, were Types CE1, CE2, CE3, CE4, and CE5, respectively. A significant correlation was noticed between the number of cysts in liver and those in lung ( R = 0.770, P < 0.001). CT scan is a suitable tool in determining the size and type of cystic hydatid cysts in both liver and lung of sheep. A significant correlation was noticed between the numbers in liver and lung, indicating that lung infection was likely due to the expansion of liver cyst burden pressure.

Phantom-based standardization of CT angiography images for spot sign detection.

PubMed

Morotti, Andrea; Romero, Javier M; Jessel, Michael J; Hernandez, Andrew M; Vashkevich, Anastasia; Schwab, Kristin; Burns, Joseph D; Shah, Qaisar A; Bergman, Thomas A; Suri, M Fareed K; Ezzeddine, Mustapha; Kirmani, Jawad F; Agarwal, Sachin; Shapshak, Angela Hays; Messe, Steven R; Venkatasubramanian, Chitra; Palmieri, Katherine; Lewandowski, Christopher; Chang, Tiffany R; Chang, Ira; Rose, David Z; Smith, Wade; Hsu, Chung Y; Liu, Chun-Lin; Lien, Li-Ming; Hsiao, Chen-Yu; Iwama, Toru; Afzal, Mohammad Rauf; Cassarly, Christy; Greenberg, Steven M; Martin, Renee' Hebert; Qureshi, Adnan I; Rosand, Jonathan; Boone, John M; Goldstein, Joshua N

2017-09-01

The CT angiography (CTA) spot sign is a strong predictor of hematoma expansion in intracerebral hemorrhage (ICH). However, CTA parameters vary widely across centers and may negatively impact spot sign accuracy in predicting ICH expansion. We developed a CT iodine calibration phantom that was scanned at different institutions in a large multicenter ICH clinical trial to determine the effect of image standardization on spot sign detection and performance. A custom phantom containing known concentrations of iodine was designed and scanned using the stroke CT protocol at each institution. Custom software was developed to read the CT volume datasets and calculate the Hounsfield unit as a function of iodine concentration for each phantom scan. CTA images obtained within 8 h from symptom onset were analyzed by two trained readers comparing the calibrated vs. uncalibrated density cutoffs for spot sign identification. ICH expansion was defined as hematoma volume growth >33%. A total of 90 subjects qualified for the study, of whom 17/83 (20.5%) experienced ICH expansion. The number of spot sign positive scans was higher in the calibrated analysis (67.8 vs 38.9% p < 0.001). All spot signs identified in the non-calibrated analysis remained positive after calibration. Calibrated CTA images had higher sensitivity for ICH expansion (76 vs 52%) but inferior specificity (35 vs 63%) compared with uncalibrated images. Normalization of CTA images using phantom data is a feasible strategy to obtain consistent image quantification for spot sign analysis across different sites and may improve sensitivity for identification of ICH expansion.

[18F]FDG PET/CT-based response assessment of stage IV non-small cell lung cancer treated with paclitaxel-carboplatin-bevacizumab with or without nitroglycerin patches.

PubMed

de Jong, Evelyn E C; van Elmpt, Wouter; Leijenaar, Ralph T H; Hoekstra, Otto S; Groen, Harry J M; Smit, Egbert F; Boellaard, Ronald; van der Noort, Vincent; Troost, Esther G C; Lambin, Philippe; Dingemans, Anne-Marie C

2017-01-01

Nitroglycerin (NTG) is a vasodilating drug, which increases tumor blood flow and consequently decreases hypoxia. Therefore, changes in [18F] fluorodeoxyglucose positron emission tomography ([18F]FDG PET) uptake pattern may occur. In this analysis, we investigated the feasibility of [18F]FDG PET for response assessment to paclitaxel-carboplatin-bevacizumab (PCB) treatment with and without NTG patches. And we compared the [18F]FDG PET response assessment to RECIST response assessment and survival. A total of 223 stage IV non-small cell lung cancer (NSCLC) patients were included in a phase II study (NCT01171170) randomizing between PCB treatment with or without NTG patches. For 60 participating patients, a baseline and a second [18F]FDG PET/computed tomography (CT) scan, performed between day 22 and 24 after the start of treatment, were available. Tumor response was defined as a 30 % decrease in CT and PET parameters, and was compared to RECIST response at week 6. The predictive value of these assessments for progression free survival (PFS) and overall survival (OS) was assessed with and without NTG. A 30 % decrease in SUVpeak assessment identified more patients as responders compared to a 30 % decrease in CT diameter assessment (73 % vs. 18 %), however, this was not correlated to OS (SUVpeak30 p = 0.833; CTdiameter30 p = 0.557). Changes in PET parameters between the baseline and the second scan were not significantly different for the NTG group compared to the control group (p value range 0.159-0.634). The CT-based (part of the [18F]FDG PET/CT) parameters showed a significant difference between the baseline and the second scan for the NTG group compared to the control group (CT diameter decrease of 7 ± 23 % vs. 19 ± 14 %, p = 0.016, respectively). The decrease in tumoral FDG uptake in advanced NSCLC patients treated with chemotherapy with and without NTG did not differ between both treatment arms. Early PET-based response assessment showed more tumor responders than CT-based response assessment (part of the [18F]FDG PET/CT); this was not correlated to survival. This might be due to timing of the [18F]FDG PET shortly after the bevacizumab infusion.

A dual tracer (68)Ga-DOTANOC PET/CT and (18)F-FDG PET/CT pilot study for detection of cardiac sarcoidosis.

PubMed

Gormsen, Lars C; Haraldsen, Ate; Kramer, Stine; Dias, Andre H; Kim, Won Yong; Borghammer, Per

2016-12-01

Cardiac sarcoidosis (CS) is a potentially fatal condition lacking a single test with acceptable diagnostic accuracy. (18)F-FDG PET/CT has emerged as a promising imaging modality, but is challenged by physiological myocardial glucose uptake. An alternative tracer, (68)Ga-DOTANOC, binds to somatostatin receptors on inflammatory cells in sarcoid granulomas. We therefore aimed to conduct a proof-of-concept study using (68)Ga-DOTANOC to diagnose CS. In addition, we compared diagnostic accuracy and inter-observer variability of (68)Ga-DOTANOC vs. (18)F-FDG PET/CT. Nineteen patients (seven female) with suspected CS were prospectively recruited and dual tracer scanned within 7 days. PET images were reviewed by four expert readers for signs of CS and compared to the reference standard (Japanese ministry of Health and Welfare CS criteria). CS was diagnosed in 3/19 patients. By consensus, 11/19 (18)F-FDG scans and 0/19 (68)Ga-DOTANOC scans were rated as inconclusive. The sensitivity of (18)F-FDG PET for diagnosing CS was 33 %, specificity was 88 %, PPV was 33 %, NPV was 88 %, and diagnostic accuracy was 79 %. For (68)Ga-DOTANOC, accuracy was 100 %. Inter-observer agreement was poor for (18)F-FDG PET (Fleiss' combined kappa 0.27, NS) and significantly better for (68)Ga-DOTANOC (Fleiss' combined kappa 0.46, p = 0.001). Despite prolonged pre-scan fasting, a large proportion of (18)F-FDG PET/CT images were rated as inconclusive, resulting in low agreement among reviewers and correspondingly poor diagnostic accuracy. By contrast, (68)Ga-DOTANOC PET/CT had excellent diagnostic accuracy with the caveat that inter-observer variability was still significant. Nevertheless, (68)Ga-DOTANOC PET/CT looks very promising as an alternative CS PET tracer. Current Controlled Trials NCT01729169 .

Low-tube-voltage selection for non-contrast-enhanced CT: Comparison of the radiation dose in pediatric and adult phantoms.

PubMed

Shimonobo, Toshiaki; Funama, Yoshinori; Utsunomiya, Daisuke; Nakaura, Takeshi; Oda, Seitaro; Kiguchi, Masao; Masuda, Takanori; Sakabe, Daisuke; Yamashita, Yasuyuki; Awai, Kazuo

2016-01-01

We used pediatric and adult anthropomorphic phantoms to compare the radiation dose of low- and standard tube voltage chest and abdominal non-contrast-enhanced computed tomography (CT) scans. We also discuss the optimal low tube voltage for non-contrast-enhanced CT. Using a female adult- and three differently-sized pediatric anthropomorphic phantoms we acquired chest and abdominal non-contrast-enhanced scans on a 320-multidetector CT volume scanner. The tube voltage was set at 80-, 100-, and 120 kVp. The tube current was automatically assigned on the CT scanner in response to the set image noise level. On each phantom and at each tube voltage we measured the surface and center dose using high-sensitivity metal-oxide-semiconductor field-effect transistor detectors. The mean surface dose of chest and abdominal CT scans in 5-year olds was 4.4 and 5.3 mGy at 80 kVp, 4.5 and 5.4 mGy at 100 kV, and 4.0 and 5.0 mGy at 120 kVp, respectively. These values were similar in our 3-pediatric phantoms (p > 0.05). The mean surface dose in the adult phantom increased from 14.7 to 19.4 mGy for chest- and from 18.7 to 24.8 mGy for abdominal CT as the tube voltage decreased from 120 to 80 kVp (p < 0.01). Compared to adults, the surface and center dose for pediatric patients is almost the same despite a decrease in the tube voltage and the low tube voltage technique can be used for non-contrast-enhanced chest- and abdominal scanning. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Single-Blinded Prospective Implementation of a Preoperative Imaging Checklist for Endoscopic Sinus Surgery.

PubMed

Error, Marc; Ashby, Shaelene; Orlandi, Richard R; Alt, Jeremiah A

2018-01-01

Objective To determine if the introduction of a systematic preoperative sinus computed tomography (CT) checklist improves identification of critical anatomic variations in sinus anatomy among patients undergoing endoscopic sinus surgery. Study Design Single-blinded prospective cohort study. Setting Tertiary care hospital. Subjects and Methods Otolaryngology residents were asked to identify critical surgical sinus anatomy on preoperative CT scans before and after introduction of a systematic approach to reviewing sinus CT scans. The percentage of correctly identified structures was documented and compared with a 2-sample t test. Results A total of 57 scans were reviewed: 28 preimplementation and 29 postimplementation. Implementation of the sinus CT checklist improved identification of critical sinus anatomy from 24% to 84% correct ( P < .001). All residents, junior and senior, demonstrated significant improvement in identification of sinus anatomic variants, including those not directly included in the systematic review implemented. Conclusion The implementation of a preoperative endoscopic sinus surgery radiographic checklist improves identification of critical anatomic sinus variations in a training population.

CT scanning in stroke patients: meeting the challenge in the remote and rural district general hospital.

PubMed

Todd, A W; Anderson, E M

2009-05-01

National audit data allow crude comparison between centres and indicate that most Scottish hospitals fail to meet current guidelines for CT scanning of the brain in stroke patients. This study identifies some of the reasons for delay in performing CT scans in a largely rural population. This audit study assesses the delays from onset of symptoms, time of admission and request received to CT scan in stroke patients for three different in-patient groups as well as those managed in the community. The reasons for delay in CT scanning varied between different patient groups but for one group of in-patients, changes in booking procedure and introduction of a second CT scanner increased the proportion scanned within 48 hours of request from 65% to 96%. Further developments including the introduction of Saturday and Sunday routine CT scanning, radiologist reporting from home and additional CT scanners placed in remote hospitals may be expected to improve these figures further. Target times of three hours from onset of symptoms to scan to allow thrombolysis may however be impossible to meet for all stroke patients in rural areas.

SU-E-T-541: Measurement of CT Density Model Variations and the Impact On the Accuracy of Monte Carlo (MC) Dose Calculation in Stereotactic Body Radiation Therapy for Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, H; Li, B; Behrman, R

2015-06-15

Purpose: To measure the CT density model variations between different CT scanners used for treatment planning and impact on the accuracy of MC dose calculation in lung SBRT. Methods: A Gammex electron density phantom (RMI 465) was scanned on two 64-slice CT scanners (GE LightSpeed VCT64) and a 16-slice CT (Philips Brilliance Big Bore CT). All three scanners had been used to acquire CT for CyberKnife lung SBRT treatment planning. To minimize the influences of beam hardening and scatter for improving reproducibility, three scans were acquired with the phantom rotated 120° between scans. The mean CT HU of each densitymore » insert, averaged over the three scans, was used to build the CT density models. For 14 patient plans, repeat MC dose calculations were performed by using the scanner-specific CT density models and compared to a baseline CT density model in the base plans. All dose re-calculations were done using the same plan beam configurations and MUs. Comparisons of dosimetric parameters included PTV volume covered by prescription dose, mean PTV dose, V5 and V20 for lungs, and the maximum dose to the closest critical organ. Results: Up to 50.7 HU variations in CT density models were observed over the baseline CT density model. For 14 patient plans examined, maximum differences in MC dose re-calculations were less than 2% in 71.4% of the cases, less than 5% in 85.7% of the cases, and 5–10% for 14.3% of the cases. As all the base plans well exceeded the clinical objectives of target coverage and OAR sparing, none of the observed differences led to clinically significant concerns. Conclusion: Marked variations of CT density models were observed for three different CT scanners. Though the differences can cause up to 5–10% differences in MC dose calculations, it was found that they caused no clinically significant concerns.« less

SU-E-I-57: Evaluation and Optimization of Effective-Dose Using Different Beam-Hardening Filters in Clinical Pediatric Shunt CT Protocol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, K; Aldoohan, S; Collier, J

Purpose: Study image optimization and radiation dose reduction in pediatric shunt CT scanning protocol through the use of different beam-hardening filters Methods: A 64-slice CT scanner at OU Childrens Hospital has been used to evaluate CT image contrast-to-noise ratio (CNR) and measure effective-doses based on the concept of CT dose index (CTDIvol) using the pediatric head shunt scanning protocol. The routine axial pediatric head shunt scanning protocol that has been optimized for the intrinsic x-ray tube filter has been used to evaluate CNR by acquiring images using the ACR approved CT-phantom and radiation dose CTphantom, which was used to measuremore » CTDIvol. These results were set as reference points to study and evaluate the effects of adding different filtering materials (i.e. Tungsten, Tantalum, Titanium, Nickel and Copper filters) to the existing filter on image quality and radiation dose. To ensure optimal image quality, the scanner routine air calibration was run for each added filter. The image CNR was evaluated for different kVps and wide range of mAs values using above mentioned beam-hardening filters. These scanning protocols were run under axial as well as under helical techniques. The CTDIvol and the effective-dose were measured and calculated for all scanning protocols and added filtration, including the intrinsic x-ray tube filter. Results: Beam-hardening filter shapes energy spectrum, which reduces the dose by 27%. No noticeable changes in image low contrast detectability Conclusion: Effective-dose is very much dependent on the CTDIVol, which is further very much dependent on beam-hardening filters. Substantial reduction in effective-dose is realized using beam-hardening filters as compare to the intrinsic filter. This phantom study showed that significant radiation dose reduction could be achieved in CT pediatric shunt scanning protocols without compromising in diagnostic value of image quality.« less

Trends and patterns in the use of computed tomography in children and young adults in Catalonia - results from the EPI-CT study.

PubMed

Bosch de Basea, Magda; Salotti, Jane A; Pearce, Mark S; Muchart, Jordi; Riera, Luis; Barber, Ignasi; Pedraza, Salvador; Pardina, Marina; Capdevila, Antoni; Espinosa, Ana; Cardis, Elisabeth

2016-01-01

Although there are undeniable diagnostic benefits of CT scanning, its increasing use in paediatric radiology has become a topic of concern regarding patient radioprotection. To assess the rate of CT scanning in Catalonia, Spain, among patients younger than 21 years old at the scan time. This is a sub-study of a larger international cohort study (EPI-CT, the International pediatric CT scan study). Data were retrieved from the radiological information systems (RIS) of eight hospitals in Catalonia since the implementation of digital registration (between 1991 and 2010) until 2013. The absolute number of CT scans annually increased 4.5% between 1991 and 2013, which was less accentuated when RIS was implemented in most hospitals. Because the population attending the hospitals also increased, however, the rate of scanned patients changed little (8.3 to 9.4 per 1,000 population). The proportions of patients with more than one CT and more than three CTs showed a 1.51- and 2.7-fold increase, respectively, over the 23 years. Gradual increases in numbers of examinations and scanned patients were observed in Catalonia, potentially explained by new CT scanning indications and increases in the availability of scanners, the number of scans per patient and the size of the attended population.

CT scan

MedlinePlus

... this page: //medlineplus.gov/ency/article/003330.htm CT scan To use the sharing features on this page, please enable JavaScript. A computed tomography (CT) scan is an imaging method that uses x- ...

Computed Tomography (CT) - Spine

MedlinePlus

... Resources Professions Site Index A-Z Computed Tomography (CT) - Spine Computed tomography (CT) of the spine is ... of CT Scanning of the Spine? What is CT Scanning of the Spine? Computed tomography, more commonly ...

Scope for energy improvement for hospital imaging services in the USA.

PubMed

Esmaeili, Amin; Twomey, Janet M; Overcash, Michael R; Soltani, Seyed A; McGuire, Charles; Ali, Kamran

2015-04-01

To aid radiologists by measuring the carbon footprint of CT scans by quantifying in-hospital and out-of-hospital energy use and to assess public health impacts. The study followed a standard life cycle assessment protocol to measure energy from a CT scan then expanding to all hospital electrical energy related to CT usage. In addition, all the fuel energy used to generate electricity and to manufacture the CT consumables was measured. The study was conducted at two hospitals. The entire life cycle energy for a CT scan was 24-34 kWh of natural resource energy per scan. The actual active patient scan energy that produces the images is only about 1.6% of this total life cycle energy. This large multiplier to get total CT energy is a previously undocumented environmental response to the direct radiology order for a patient CT scan. The CT in-hospital energy related to idle periods, where the machine is on but no patients are being scanned and is 14-30-fold higher than the energy used for the CT image. The in-hospital electrical energy of a CT scan makes up only about 25% of the total energy footprint. The rest is generated outside the hospital: 54-62% for generation and transmission of the electricity, while 13-22% is for all the energy to make the consumables. Different CT scanners have some influences on the results and could help guide purchase of CT equipment. The transparent, detailed life cycle approach allows the data from this study to be used by radiologists to examine details of both direct and of unseen energy impacts of CT scans. The public health (outside-the-hospital) impact (including the patients receiving a CT) needs to be measured and included. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Raman and CT scan mapping of chalcogenide glass diffusion generated gradient index profiles

NASA Astrophysics Data System (ADS)

Lindberg, G. P.; Berg, R. H.; Deegan, J.; Benson, R.; Salvaggio, P. S.; Gross, N.; Weinstein, B. A.; Gibson, D.; Bayya, S.; Sanghera, J.; Nguyen, V.; Kotov, M.

2016-05-01

Metrology of a gradient index (GRIN) material is non-trivial, especially in the realm of infrared and large refractive index. Traditional methods rely on index matching fluids which are not available for indexes as high as those found in the chalcogenide glasses (2.4-3.2). By diffusing chalcogenide glasses of similar composition one can blend the properties in a continuous way. In an effort to measure this we will present data from both x-ray computed tomography scans (CT scans) and Raman mapping scans of the diffusion profiles. Proof of concept measurements on undiffused bonded sheets of chalcogenide glasses were presented previously. The profiles measured will be of axially stacked sheets of chalcogenide glasses diffused to create a linear GRIN profile and nested tubes of chalcogenide glasses diffused to create a radial parabolic GRIN profile. We will show that the x-ray absorption in the CT scan and the intensity of select Raman peaks spatially measured through the material are indicators of the concentration of the diffusion ions and correlate to the spatial change in refractive index. We will also present finite element modeling (FEM) results and compare them to post precision glass molded (PGM) elements that have undergone CT and Raman mapping.

The prevalence of osteoarthritis of the sternoclavicular joint on computed tomography.

PubMed

Lawrence, Christopher R; East, Benjamin; Rashid, Abbas; Tytherleigh-Strong, Graham M

2017-01-01

Symptomatic disorders around the sternoclavicular joint (SCJ) are relatively uncommon. Previous cadaveric and radiographic studies have suggested that asymptomatic osteoarthritic changes are relatively common, progressively increasing with age. The purpose of this study was to determine the prevalence of SCJ osteoarthritis in the general population using computed tomography (CT) scans. We assessed 464 SCJs in 232 patients undergoing a standardized axial CT scan of the thorax including both SCJs, across a range of ages from the second to tenth decade. The scans were undertaken for multiple clinical indications; however, none were obtained to investigate SCJ pathology. The predominant changes investigated were for the features associated with osteoarthritis including the presence of osteophytes, subchondral cysts, and subcortical sclerosis. The CT scans of 244 SCJs (53%) in 137 patients (59%) showed at least 1 sign of osteoarthritis. No patients younger than 35 years had any features of osteoarthritis. Osteoarthritic changes were present in 89.6% of patients older than 50 years compared with 9.1% younger than this age. All patients above the age of 61 had at least 1 feature of osteoarthritic changes on at least 1 side of the SCJ. Increasing prevalence was noted with increasing age both in the percentage of SCJs showing any positive signs of osteoarthritis and in the severity of osteoarthritis. SCJ osteoarthritis is a very common incidental finding on CT scans, particularly with increasing age. This should be taken into consideration when using a CT scan to assess a patient with symptomatic SCJ pathology. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

High-throughput multiple-mouse imaging with micro-PET/CT for whole-skeleton assessment.

PubMed

Yagi, Masashi; Arentsen, Luke; Shanley, Ryan M; Hui, Susanta K

2014-11-01

Recent studies have proven that skeleton-wide functional assessment is essential to comprehensively understand physiological aspects of the skeletal system. Therefore, in contrast to regional imaging studies utilizing a multiple-animal holder (mouse hotel), we attempted to develop and characterize a multiple-mouse imaging system with micro-PET/CT for high-throughput whole-skeleton assessment. Using items found in a laboratory, a simple mouse hotel that houses four mice linked with gas anesthesia was constructed. A mouse-simulating phantom was used to measure uniformity in a cross sectional area and flatness (Amax/Amin*100) along the axial, radial and tangential directions, where Amax and Amin are maximum and minimum activity concentration in the profile, respectively. Fourteen mice were used for single- or multiple-micro-PET/CT scans. NaF uptake was measured at eight skeletal sites (skull to tibia). Skeletal (18)F activities measured with mice in the mouse hotel were within 1.6 ± 4% (mean ± standard deviation) of those measured with mice in the single-mouse holder. Single-holder scanning yields slightly better uniformity and flatness over the hotel. Compared to use of the single-mouse holder, scanning with the mouse hotel reduced study time (by 65%), decreased the number of scans (four-fold), reduced cost, required less computer storage space (40%), and maximized (18)F usage. The mouse hotel allows high-throughput, quantitatively equivalent scanning compared to the single-mouse holder for micro-PET/CT imaging for whole-skeleton assessment of mice. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Heart CT scan

MedlinePlus

... Computed tomography scan - heart; Calcium scoring; Multi-detector CT scan - heart; Electron beam computed tomography - heart; Agatston ... table that slides into the center of the CT scanner. You will lie on your back with ...

A prototype piecewise-linear dynamic attenuator

NASA Astrophysics Data System (ADS)

Hsieh, Scott S.; Peng, Mark V.; May, Christopher A.; Shunhavanich, Picha; Fleischmann, Dominik; Pelc, Norbert J.

2016-07-01

The piecewise-linear dynamic attenuator has been proposed as a mechanism in CT scanning for personalizing the x-ray illumination on a patient- and application-specific basis. Previous simulations have shown benefits in image quality, scatter, and dose objectives. We report on the first prototype implementation. This prototype is reduced in scale and speed and is integrated into a tabletop CT system with a smaller field of view (25 cm) and longer scan time (42 s) compared to a clinical system. Stainless steel wedges were machined and affixed to linear actuators, which were in turn held secure by a frame built using rapid prototyping technologies. The actuators were computer-controlled, with characteristic noise of about 100 microns. Simulations suggest that in a clinical setting, the impact of actuator noise could lead to artifacts of only 1 HU. Ring artifacts were minimized by careful design of the wedges. A water beam hardening correction was applied and the scan was collimated to reduce scatter. We scanned a 16 cm water cylinder phantom as well as an anthropomorphic pediatric phantom. The artifacts present in reconstructed images are comparable to artifacts normally seen with this tabletop system. Compared to a flat-field reference scan, increased detectability at reduced dose is shown and streaking is reduced. Artifacts are modest in our images and further refinement is possible. Issues of mechanical speed and stability in the challenging clinical CT environment will be addressed in a future design.

Lesion Detection in CT Images Using Deep Learning Semantic Segmentation Technique

NASA Astrophysics Data System (ADS)

Kalinovsky, A.; Liauchuk, V.; Tarasau, A.

2017-05-01

In this paper, the problem of automatic detection of tuberculosis lesion on 3D lung CT images is considered as a benchmark for testing out algorithms based on a modern concept of Deep Learning. For training and testing of the algorithms a domestic dataset of 338 3D CT scans of tuberculosis patients with manually labelled lesions was used. The algorithms which are based on using Deep Convolutional Networks were implemented and applied in three different ways including slice-wise lesion detection in 2D images using semantic segmentation, slice-wise lesion detection in 2D images using sliding window technique as well as straightforward detection of lesions via semantic segmentation in whole 3D CT scans. The algorithms demonstrate superior performance compared to algorithms based on conventional image analysis methods.

Multi-scale imaging and elastic simulation of carbonates

NASA Astrophysics Data System (ADS)

Faisal, Titly Farhana; Awedalkarim, Ahmed; Jouini, Mohamed Soufiane; Jouiad, Mustapha; Chevalier, Sylvie; Sassi, Mohamed

2016-05-01

Digital Rock Physics (DRP) is an emerging technology that can be used to generate high quality, fast and cost effective special core analysis (SCAL) properties compared to conventional experimental techniques and modeling techniques. The primary workflow of DRP conssits of three elements: 1) image the rock sample using high resolution 3D scanning techniques (e.g. micro CT, FIB/SEM), 2) process and digitize the images by segmenting the pore and matrix phases 3) simulate the desired physical properties of the rocks such as elastic moduli and velocities of wave propagation. A Finite Element Method based algorithm, that discretizes the basic Hooke's Law equation of linear elasticity and solves it numerically using a fast conjugate gradient solver, developed by Garboczi and Day [1] is used for mechanical and elastic property simulations. This elastic algorithm works directly on the digital images by treating each pixel as an element. The images are assumed to have periodic constant-strain boundary condition. The bulk and shear moduli of the different phases are required inputs. For standard 1.5" diameter cores however the Micro-CT scanning reoslution (around 40 μm) does not reveal smaller micro- and nano- pores beyond the resolution. This results in an unresolved "microporous" phase, the moduli of which is uncertain. Knackstedt et al. [2] assigned effective elastic moduli to the microporous phase based on self-consistent theory (which gives good estimation of velocities for well cemented granular media). Jouini et al. [3] segmented the core plug CT scan image into three phases and assumed that micro porous phase is represented by a sub-extracted micro plug (which too was scanned using Micro-CT). Currently the elastic numerical simulations based on CT-images alone largely overpredict the bulk, shear and Young's modulus when compared to laboratory acoustic tests of the same rocks. For greater accuracy of numerical simulation prediction, better estimates of moduli inputs for this current unresolved phase is important. In this work we take a multi-scale imaging approach by first extracting a smaller 0.5" core and scanning at approx 13 µm, then further extracting a 5mm diameter core scanned at 5 μm. From this last scale, region of interests (containing unresolved areas) are identified for scanning at higher resolutions using Focalised Ion Beam (FIB/SEM) scanning technique reaching 50 nm resolution. Numerical simulation is run on such a small unresolved section to obtain a better estimate of the effective moduli which is then used as input for simulations performed using CT-images. Results are compared with expeirmental acoustic test moduli obtained also at two scales: 1.5" and 0.5" diameter cores.

Over-exposure correction in knee cone-beam CT imaging with automatic exposure control using a partial low dose scan

NASA Astrophysics Data System (ADS)

Choi, Jang-Hwan; Muller, Kerstin; Hsieh, Scott; Maier, Andreas; Gold, Garry; Levenston, Marc; Fahrig, Rebecca

2016-03-01

C-arm-based cone-beam CT (CBCT) systems with flat-panel detectors are suitable for diagnostic knee imaging due to their potentially flexible selection of CT trajectories and wide volumetric beam coverage. In knee CT imaging, over-exposure artifacts can occur because of limitations in the dynamic range of the flat panel detectors present on most CBCT systems. We developed a straightforward but effective method for correction and detection of over-exposure for an Automatic Exposure Control (AEC)-enabled standard knee scan incorporating a prior low dose scan. The radiation dose associated with the low dose scan was negligible (0.0042mSv, 2.8% increase) which was enabled by partially sampling the projection images considering the geometry of the knees and lowering the dose further to be able to just see the skin-air interface. We combined the line integrals from the AEC and low dose scans after detecting over-exposed regions by comparing the line profiles of the two scans detector row-wise. The combined line integrals were reconstructed into a volumetric image using filtered back projection. We evaluated our method using in vivo human subject knee data. The proposed method effectively corrected and detected over-exposure, and thus recovered the visibility of exterior tissues (e.g., the shape and density of the patella, and the patellar tendon), incorporating a prior low dose scan with a negligible increase in radiation exposure.

Role of Positron Emission Tomography-Computed Tomography in the Management of Anal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mistrangelo, Massimiliano, E-mail: mistrangelo@katamail.com; Pelosi, Ettore; Bello, Marilena

2012-09-01

Purpose: Pre- and post-treatment staging of anal cancer are often inaccurate. The role of positron emission tomograpy-computed tomography (PET-CT) in anal cancer is yet to be defined. The aim of the study was to compare PET-CT with CT scan, sentinel node biopsy results of inguinal lymph nodes, and anal biopsy results in staging and in follow-up of anal cancer. Methods and Materials: Fifty-three consecutive patients diagnosed with anal cancer underwent PET-CT. Results were compared with computed tomography (CT), performed in 40 patients, and with sentinel node biopsy (SNB) (41 patients) at pretreatment workup. Early follow-up consisted of a digital rectalmore » examination, an anoscopy, a PET-CT scan, and anal biopsies performed at 1 and 3 months after the end of treatment. Data sets were then compared. Results: At pretreatment assessment, anal cancer was identified by PET-CT in 47 patients (88.7%) and by CT in 30 patients (75%). The detection rates rose to 97.9% with PET-CT and to 82.9% with CT (P=.042) when the 5 patients who had undergone surgery prior to this assessment and whose margins were positive at histological examination were censored. Perirectal and/or pelvic nodes were considered metastatic by PET-CT in 14 of 53 patients (26.4%) and by CT in 7 of 40 patients (17.5%). SNB was superior to both PET-CT and CT in detecting inguinal lymph nodes. PET-CT upstaged 37.5% of patients and downstaged 25% of patients. Radiation fields were changed in 12.6% of patients. PET-CT at 3 months was more accurate than PET-CT at 1 month in evaluating outcomes after chemoradiation therapy treatment: sensitivity was 100% vs 66.6%, and specificity was 97.4% vs 92.5%, respectively. Median follow-up was 20.3 months. Conclusions: In this series, PET-CT detected the primary tumor more often than CT. Staging of perirectal/pelvic or inguinal lymph nodes was better with PET-CT. SNB was more accurate in staging inguinal lymph nodes.« less

High-resolution three-dimensional visualization of the rat spinal cord microvasculature by synchrotron radiation micro-CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Jianzhong; Cao, Yong; Wu, Tianding

2014-10-15

Purpose: Understanding the three-dimensional (3D) morphology of the spinal cord microvasculature has been limited by the lack of an effective high-resolution imaging technique. In this study, synchrotron radiation microcomputed tomography (SRµCT), a novel imaging technique based on absorption imaging, was evaluated with regard to the detection of the 3D morphology of the rat spinal cord microvasculature. Methods: Ten Sprague-Dawley rats were used in this ex vivo study. After contrast agent perfusion, their spinal cords were isolated and scanned using conventional x-rays, conventional micro-CT (CµCT), and SRµCT. Results: Based on contrast agent perfusion, the microvasculature of the rat spinal cord wasmore » clearly visualized for the first time ex vivo in 3D by means of SRµCT scanning. Compared to conventional imaging techniques, SRµCT achieved higher resolution 3D vascular imaging, with the smallest vessel that could be distinguished approximately 7.4 μm in diameter. Additionally, a 3D pseudocolored image of the spinal cord microvasculature was generated in a single session of SRµCT imaging, which was conducive to detailed observation of the vessel morphology. Conclusions: The results of this study indicated that SRµCT scanning could provide higher resolution images of the vascular network of the spinal cord. This modality also has the potential to serve as a powerful imaging tool for the investigation of morphology changes in the 3D angioarchitecture of the neurovasculature in preclinical research.« less

Analysis of pulmonary pure ground-glass nodule in enhanced dual energy CT imaging for predicting invasive adenocarcinoma: comparing with conventional thin-section CT imaging

PubMed Central

Zhang, Ying; Tang, Jian; Xu, Jianrong

2017-01-01

Background To investigate the value of dual energy computed tomography (DECT) parameters (including iodine concentration and monochromatic CT numbers) for predicting pure ground-glass nodules (pGGNs) of invasive adenocarcinoma (IA). Methods A total of 55 resected pGGNs evaluated with both unenhanced thin-section CT (TSCT) and enhanced DECT scans were included. Correlations between histopathology [adenocarcinoma in situ (AIS), minimally IA (MIA), and IA] and CT scan characteristics were examined. CT scan and clinicodemographic data were investigated by univariate and multivariate analysis to identify features that helped distinguish IA from AIS or MIA. Results Both normalized iodine concentration (NIC) of IA and slope of spectral curve [slope(k)] were not significantly different between IA and AIS or MIA. Size, performance of pleural retraction and enhanced monochromatic CT attenuation values of 120–140 keV were significantly higher for IA. In multivariate regression analysis, size and enhanced monochromatic CT number of 140 keV were independent predictors for IA. Using the two parameters together, the diagnostic capacity of IA could be improved from 0.697 or 0.635 to 0.713. Conclusions DECT could help demonstrate blood supply and indicate invasion extent of pGGNs, and monochromatic CT number of higher energy (especially 140 keV) would be better for diagnosing IA than lower energies. Together with size of pGGNs, the diagnostic capacity of IA could be better. PMID:29312701

Computed tomography of patients with head trauma following road traffic accident in Benin City, Nigeria.

PubMed

Eze, K C; Mazeli, F O

2011-01-01

The outcome of head trauma as a result of road accident rests with increased use of CT scan and other radiological imaging modalities for prompt diagnosis is important. To find out the time of presentation for CT scan, symptoms for referral for CT scan and pattern of injuries in patients with cranial CT scan following road traffic accidents. Retrospective analysis of cranial computed tomography (CT) films, request cards, duplicate copy of radiology reports, soft copy CT images and case notes of 61 patients who underwent cranial CT scan on account of road traffic accidents. The study CT scans were performed at the radiology department of University Teaching Hospital between 1st January 2002 and 31st December 2004. 51 patients (83.6%) were male while 10 (16.4%) were female with male to female ratio of 5:1. Thirty - eight (62.3%) patients were aged 20-39 years. Forty two patients (68.9%) presented after one week of injury. No patient presented within the first six hours of injury. The symptoms needing referral for CT scan included head injury 30 (49.2%), seizures 10 16.4%), skull fractures 8 (13.1%) and persistent headache 6 (5.6%). A total of 113 lesions were seen as some patients presented with more than one lesion. The findings on CT scan included 10 patients with normal findings , 21 (34.4%) skull fractures , 21 (34.4%) intra-cerebral haemorrhage , 19 (31.2%) brain contusion , 18 (29.5%) paranasal sinus collection,11 (18.0%) cerebral oedema, 10 (16.4%) subdural haematoma and 5 (8.2%) epidural haematoma. Over 80% of the subdural and epidural haematomas were associated with skull fractures. The yield from plain radiography was poor being positive in only 8 (13.1%) while CT scan was positive in 51 (83.61%). Also 75 (about 66%) of the 113 lesions seen on CT scan were treatable surgically. CT scan is an effective imaging modality of patient with road traffic accident and should be promptly requested in symptomatic patients who sustain trauma to the head toward identification of lesions that are amenable to surgical treatment.

CT Scans

MedlinePlus

... cross-sectional pictures of your body. Doctors use CT scans to look for Broken bones Cancers Blood clots Signs of heart disease Internal bleeding During a CT scan, you lie still on a table. The table ...

Relationship of Coronary Calcium on Standard Chest CT Scans With Mortality.

PubMed

Hughes-Austin, Jan M; Dominguez, Arturo; Allison, Matthew A; Wassel, Christina L; Rifkin, Dena E; Morgan, Cindy G; Daniels, Michael R; Ikram, Umaira; Knox, Jessica B; Wright, C Michael; Criqui, Michael H; Ix, Joachim H

2016-02-01

The aim of this study was to determine the correlation between coronary artery calcium (CAC) scores on 3 mm electrocardiography (ECG)-gated computed tomography (CT) scans and standard 6 mm chest CT scans, and to compare relative strength of associations of CAC on each scan type with mortality risk. Coronary artery calcification predicts cardiovascular disease (CVD) and all-cause mortality, and is typically measured on ECG-gated 3 mm CT scans. Patients undergo standard 6 mm chest CTs for various clinical indications much more frequently, but CAC is not usually quantified. To better understand the usefulness of standard chest CTs to quantify CAC, we conducted a case-control study among persons who had both scan types. Between 2000 and 2003, 4,544 community-living individuals self- or physician-referred for "whole-body" CT scans, had 3 mm ECG-gated CTs and standard 6 mm chest CTs, and were followed for mortality through 2009. In this nested case-control study, we identified 157 deaths and 494 controls frequency matched (1:3) on age and sex. The Agatston method quantified CAC on both scan types. Unconditional logistic regression determined associations with mortality, accounting for CVD risk factors. Participants were 68 ± 11 years of age and 63% male. The Spearman correlation of CAC scores between the 2 scan types was 0.93 (p < 0.001); median CAC scores were lower on 6 mm CTs compared to 3 mm CTs (22 vs.104 Agatston units, p < 0.001). Adjusted for traditional CVD risk factors, each standard deviation higher CAC score on 6 mm CTs was associated with 50% higher odds of death (odds ratio: 1.5; 95% confidence interval: 1.2 to 1.9), similar to 50% higher odds on the 3 mm ECG-gated CTs (odds ratio: 1.5; 95% confidence interval: 1.1 to 1.9). CAC scores on standard 6 mm chest CTs are strongly correlated with 3 mm ECG-gated CTs and similarly predict mortality in community-living individuals. Chest CTs performed for other clinical indications may provide an untapped resource to garner CVD risk information without additional radiation exposure or expense. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

A Strange Case of Downward Displacement of a Deep Brain Stimulation Electrode 10 Years Following Implantation: The Gliding Movement of Snakes Theory.

PubMed

Iacopino, Domenico Gerardo; Maugeri, Rosario; Giugno, Antonella; Giller, Cole A

2015-08-01

Despite the best efforts to ensure stereotactic precision, deep brain stimulation (DBS) electrodes can wander from their intended position after implantation. We report a case of downward electrode migration 10 years following successful implantation in a patient with Parkinson disease. A 53-year-old man with Parkinson disease underwent bilateral implantation of DBS electrodes connected to a subclavicular 2-channel pulse generator. The generator was replaced 7 years later, and a computed tomography (CT) scan confirmed the correct position of both leads. The patient developed a gradual worsening affecting his right side 3 years later, 10 years after the original implantation. A CT scan revealed displacement of the left electrode inferiorly into the pons. The new CT scans and the CT scans obtained immediately after the implantation were merged within a stereotactic planning workstation (Brainlab). Comparing the CT scans, the distal end of the electrode was in the same position, the proximal tip being significantly more inferior. The size and configuration of the coiled portions of the electrode had not changed. At implantation, the length was 27.7 cm; after 10 years, the length was 30.6 cm. These data suggests that the electrode had been stretched into its new position rather than pushed. Clinicians evaluating patients with a delayed worsening should be aware of this rare event. Copyright © 2015 Elsevier Inc. All rights reserved.

Alcohol-related hospitalisations of trauma patients in Southern Taiwan: a cross-sectional study based on a trauma registry system

PubMed Central

Rau, Cheng-Shyuan; Liu, Hang-Tsung; Hsu, Shiun-Yuan; Cho, Tzu-Yu; Hsieh, Ching-Hua

2014-01-01

Objectives To provide an overview of the demographic characteristics of patients with positive blood alcohol concentration (BAC) and to investigate the performance of brain CT scans in these patients. Design Cross-sectional study. Setting Taiwan. Participants 2192 patients who had undergone a test for blood alcohol of 13 233 patients registered in the Trauma Registry System between 1 January 2009 and 31 December 2012. A BAC level of 50 mg/dL was defined as the cut-off value. Detailed information was retrieved from the patients with positive BAC (n=793) and was compared with information from those with a negative BAC (n=1399). Main outcome measures Glasgow Coma Scale (GCS) and Injury Severity Score (ISS) as well as the performance and findings of obtained brain CT scans. Results Patients with positive BAC had a higher rate of face injury, but a lower GCS score, a lower rate of head and neck injury, a lower ISS and New Injury Severity Score. Alcohol use was associated with a shorter length of hospital stay (8.6 vs 11.4 days, p=0.000) in patients with an ISS of <16. Of 496 patients with positive BAC who underwent brain CT, 164 (33.1%) showed positive findings on CT scan. In contrast, of 891 patients with negative BAC who underwent brain CT, 389 (43.7%) had positive findings on CT scan. The lower percentage of positive CT scan findings in patients with positive BAC was particularly evident in patients with an ISS <16 (18.0% vs 28.8%, p=0.001). Conclusions Patients who consumed alcohol tended to have a low GCS score and injuries that were less severe. However, given the significantly low percentage of positive findings, brain CT might be overused in these patients with less severe injuries. PMID:25361838

Optimization of a secondary VOI protocol for lung imaging in a clinical CT scanner.

PubMed

Larsen, Thomas C; Gopalakrishnan, Vissagan; Yao, Jianhua; Nguyen, Catherine P; Chen, Marcus Y; Moss, Joel; Wen, Han

2018-05-21

We present a solution to meet an unmet clinical need of an in-situ "close look" at a pulmonary nodule or at the margins of a pulmonary cyst revealed by a primary (screening) chest CT while the patient is still in the scanner. We first evaluated options available on current whole-body CT scanners for high resolution screening scans, including ROI reconstruction of the primary scan data and HRCT, but found them to have insufficient SNR in lung tissue or discontinuous slice coverage. Within the capabilities of current clinical CT systems, we opted for the solution of a secondary, volume-of-interest (VOI) protocol where the radiation dose is focused into a short-beam axial scan at the z position of interest, combined with a small-FOV reconstruction at the xy position of interest. The objective of this work was to design a VOI protocol that is optimized for targeted lung imaging in a clinical whole-body CT system. Using a chest phantom containing a lung-mimicking foam insert with a simulated cyst, we identified the appropriate scan mode and optimized both the scan and recon parameters. The VOI protocol yielded 3.2 times the texture amplitude-to-noise ratio in the lung-mimicking foam when compared to the standard chest CT, and 8.4 times the texture difference between the lung mimicking and reference foams. It improved details of the wall of the simulated cyst and better resolution in a line-pair insert. The Effective Dose of the secondary VOI protocol was 42% on average and up to 100% in the worst-case scenario of VOI positioning relative to the standard chest CT. The optimized protocol will be used to obtain detailed CT textures of pulmonary lesions, which are biomarkers for the type and stage of lung diseases. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Comparison of conventional and synchrotron-radiation-based microtomography of bone around dental implants

NASA Astrophysics Data System (ADS)

Cattaneo, Paolo M.; Dalstra, Michel; Beckmann, Felix; Donath, Tilman; Melsen, Birte

2004-10-01

This study explores the application of conventional micro tomography (μCT) and synchrotron radiation (SR) based μCT to evaluate the bone around titanium dental implants. The SR experiment was performed at beamline W2 of HASYLAB at DESY using a monochromatic X-ray beam of 50 keV. The testing material consisted of undecalcified bone segments harvested from the upper jaw of a macaca fascicularis monkey each containing a titanium dental implant. The results from the two different techniques were qualitatively compared with conventional histological sections examined under light microscopy. The SR-based μCT produced images that, especially at the bone-implant interface, are less noisy and sharper than the ones obtained with conventional μCT. For the proper evaluation of the implant-bone interface, only the SR-based μCT technique is able to display the areas of bony contact and visualize the true 3D structure of bone around dental implants correctly. This investigation shows that both conventional and SR-based μCT scanning techniques are non-destructive methods, which provide detailed images of bone. However with SR-based μCT it is possible to obtain an improved image quality of the bone surrounding dental implants, which display a level of detail comparable to histological sections. Therefore, SR-based μCT scanning could represent a valid, unbiased three-dimensional alternative to evaluate osseointegration of dental implants

Multienergy CT acquisition and reconstruction with a stepped tube potential scan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Le; Xing, Yuxiang, E-mail: xingyx@mail.tsinghua.edu.cn

Purpose: Based on an energy-dependent property of matter, one may obtain a pseudomonochromatic attenuation map, a material composition image, an electron-density distribution, and an atomic number image using a dual- or multienergy computed tomography (CT) scan. Dual- and multienergy CT scans broaden the potential of x-ray CT imaging. The development of such systems is very useful in both medical and industrial investigations. In this paper, the authors propose a new dual- and multienergy CT system design (segmental multienergy CT, SegMECT) using an innovative scanning scheme that is conveniently implemented on a conventional single-energy CT system. The two-step-energy dual-energy CT canmore » be regarded as a special case of SegMECT. A special reconstruction method is proposed to support SegMECT. Methods: In their SegMECT, a circular trajectory in a CT scan is angularly divided into several arcs. The x-ray source is set to a different tube voltage for each arc of the trajectory. Thus, the authors only need to make a few step changes to the x-ray energy during the scan to complete a multienergy data acquisition. With such a data set, the image reconstruction might suffer from severe limited-angle artifacts if using conventional reconstruction methods. To solve the problem, they present a new prior-image-based reconstruction technique using a total variance norm of a quotient image constraint. On the one hand, the prior extracts structural information from all of the projection data. On the other hand, the effect from a possibly imprecise intensity level of the prior can be mitigated by minimizing the total variance of a quotient image. Results: The authors present a new scheme for a SegMECT configuration and establish a reconstruction method for such a system. Both numerical simulation and a practical phantom experiment are conducted to validate the proposed reconstruction method and the effectiveness of the system design. The results demonstrate that the proposed SegMECT can provide both attenuation images and material decomposition images of reasonable image quality. Compared to existing methods, the new system configuration demonstrates advantages in simplicity of implementation, system cost, and dose control. Conclusions: This proposed SegMECT imaging approach has great potential for practical applications. It can be readily realized on a conventional CT system.« less

Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alva-Sánchez, Héctor, E-mail: halva@ciencias.unam.mx; Reynoso-Mejía, Alberto; Casares-Cruz, Katiuzka

In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guidemore » provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.« less

Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

NASA Astrophysics Data System (ADS)

Alva-Sánchez, Héctor; Reynoso-Mejía, Alberto; Casares-Cruz, Katiuzka; Taboada-Barajas, Jesús

2014-11-01

In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

Radionuclide bone scan SPECT-CT: lowering the dose of CT significantly reduces radiation dose without impacting CT image quality

PubMed Central

Gupta, Sandeep Kumar; Trethewey, Scott; Brooker, Bree; Rutherford, Natalie; Diffey, Jenny; Viswanathan, Suresh; Attia, John

2017-01-01

The CT component of SPECT-CT is required for attenuation correction and anatomical localization of the uptake on SPECT but there is no guideline about the optimal CT acquisition parameters. In our department, a standard CT acquisition protocol was changed in 2013 to give lower radiation dose to the patient. In this study, we retrospectively compared the effects on patient dose as well as the CT image quality with current versus older CT protocols. Ninety nine consecutive patients [n=51 Standard dose ‘old’ protocol (SDP); n=48 lower dose ‘new’ protocol (LDP)] with lumbar spine SPECT-CT for bone scan were examined. The main differences between the two protocols were that SDP used 130 kVp tube voltage and reference current-time product of 70 mAs whereas the LDP used 110 kVp and 40 mAs respectively. Various quantitative parameters from the CT images were obtained and the images were also rated blindly by two experienced nuclear medicine physicians for bony definition and noise. The mean calculated dose length product of the LDP group (121.5±39.6 mGy.cm) was significantly lower compared to the SDP group patients (266.9±96.9 mGy.cm; P<0.0001). This translated into a significant reduction in the mean effective dose to 1.8 mSv from 4.0 mSv. The physicians reported better CT image quality for the bony structures in LDP group although for soft tissue structures, the SDP group had better image quality. The optimized new CT acquisition protocol significantly reduced the radiation dose to the patient and in-fact improved CT image quality for the assessment of bony structures. PMID:28533938

Aortic valve calcification - a commonly observed but frequently ignored finding during CT scanning of the chest.

PubMed

Raju, Prashanth; Sallomi, David; George, Bindu; Patel, Hitesh; Patel, Nikhil; Lloyd, Guy

2012-06-01

To describe the frequency and severity of Aortic valve calcification (AVC) in an unselected cohort of patients undergoing chest CT scanning and to assess the frequency with which AVC was being reported in the radiology reports. Consecutive CT scan images of the chest and the radiological reports (December 2009 to May 2010) were reviewed at the district general hospital (DGH). AVC on CT scan was visually graded on a scale ranging from 0 to IV (0 = no calcification, IV = severe calcification). Total of 416 (232 male; 184 female) CT chest scans [Contrast enhanced 302 (72%), unenhanced 114 (28%)] were reviewed. Mean age was 70.55 ± 11.48 years. AVC in CT scans was identified in 95 of the 416 patients (22.83%). AVC classification was as follows: Grade I: 60 (63.15%), Grade II: 22 (23.15%), Grade III: 9 (9.47%), Grade IV: 4 (4.21%). Only one CT report mentioned AVC. Only 31 of 95 AVC had Transthoracic echocardiogram (TTE). The interval time between CT scan and TTE was variable.   Aortic valve calcification in CT chest scans is a common finding and studies have shown that it is strongly related to the presence and severity of aortic valve disease. As CT scans are considered as a valuable additional screening tool for detection of aortic stenosis, AVC should always be commented upon in the radiology reports. Furthermore, patients with at least Grade III and IV AVC should be sent for TTE. © 2012 Blackwell Publishing Ltd.

[Spiral CT of the head-neck area: the advantages of the early arterial phase in the detection of squamous-cell carcinomas].

PubMed

Conrad, R; Pauleit, D; Layer, G; Kandyba, J; Kohlbecher, R; Hortling, N; Baselides, P; Schild, H

1999-07-01

To determine if scanning in the arterial phase improves detection of squamous cell carcinomas in the pharynx and larynx. In a prospective clinical study 20 patients with a pharyngeal or laryngeal carcinoma were examined with by spiral CT. 80 ml lopromid were intravenously injected as a bolus with a rate of 3 ml/sec. Two consecutive spiral CT scans were performed with start-delay times of 20 and 70 seconds respectively. Delineation and contrast enhancement of tumours, cervical lymph nodes and vessels were evaluated. The radiodensities (HU) of tumors, lymph nodes vessels, pharyngeal wall and muscle were measured. Comparing early and late start delay time scans tumor assessment in the early phase was better in 58%, less in 16% and equal in both scans in 26%. 82% of the pathologic lymph nodes had more peripheral enhancement than surrounding muscle tissue. During the arterial phase the measured radiodensities of the common carotid artery and jugular vein were significantly higher than in the second phase. Contrast-enhanced special CT permits accurate morphologic assessment (size, infiltration) of pharyngeal and supraglottic laryngeal squamous cell carcinoma, while pathologic lymph nodes already have a sufficient contrast enhancement for the detection.

Software Development for Estimating the Conversion Factor (K-Factor) at Suitable Scan Areas, Relating the Dose Length Product to the Effective Dose.

PubMed

Kobayashi, Masanao; Asada, Yasuki; Matsubara, Kosuke; Suzuki, Syouichi; Koshida, Kichiro; Matsunaga, Yuta; Kawaguchi, Ai; Haba, Tomonobu; Toyama, Hiroshi; Kato, Ryouichi

2017-05-01

We developed a k-factor-creator software (kFC) that provides the k-factor for CT examination in an arbitrary scan area. It provides the k-factor from the effective dose and dose-length product by Imaging Performance Assessment of CT scanners and CT-EXPO. To assess the reliability, we compared the kFC-evaluated k-factors with those of the International Commission on Radiological Protection (ICRP) publication 102. To confirm the utility, the effective dose determined by coronary computed tomographic angiography (CCTA) was evaluated by a phantom study and k-factor studies. In the CCTA, the effective doses were 5.28 mSv in the phantom study, 2.57 mSv (51%) in the k-factor of ICRP, and 5.26 mSv (1%) in the k-factor of the kFC. Effective doses can be determined from the kFC-evaluated k-factors in suitable scan areas. Therefore, we speculate that the flexible k-factor is useful in clinical practice, because CT examinations are performed in various scan regions. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Colitis detection on abdominal CT scans by rich feature hierarchies

NASA Astrophysics Data System (ADS)

Liu, Jiamin; Lay, Nathan; Wei, Zhuoshi; Lu, Le; Kim, Lauren; Turkbey, Evrim; Summers, Ronald M.

2016-03-01

Colitis is inflammation of the colon due to neutropenia, inflammatory bowel disease (such as Crohn disease), infection and immune compromise. Colitis is often associated with thickening of the colon wall. The wall of a colon afflicted with colitis is much thicker than normal. For example, the mean wall thickness in Crohn disease is 11-13 mm compared to the wall of the normal colon that should measure less than 3 mm. Colitis can be debilitating or life threatening, and early detection is essential to initiate proper treatment. In this work, we apply high-capacity convolutional neural networks (CNNs) to bottom-up region proposals to detect potential colitis on CT scans. Our method first generates around 3000 category-independent region proposals for each slice of the input CT scan using selective search. Then, a fixed-length feature vector is extracted from each region proposal using a CNN. Finally, each region proposal is classified and assigned a confidence score with linear SVMs. We applied the detection method to 260 images from 26 CT scans of patients with colitis for evaluation. The detection system can achieve 0.85 sensitivity at 1 false positive per image.

Study of dosimetric variation due to interfraction organ movement in High Dose Rate Interstital (MUPIT) brachytherapy for gynecologic malignancies

NASA Astrophysics Data System (ADS)

Velmurugan, Thanigaimalai; Sukumar, Prabakar; Krishnappan, Chokkalingam; Boopathy, Raghavendiran

2010-01-01

Ten patients with cancer of uterine cervix who underwent interstitial brachytherapy using MUPIT templates were CT scanned (CT1) using which bladder, rectum and CTV were delineated. The treatment plan PCT1 was generated and optimized geometrically on the volume. CT scan (CT2) was repeated before the second fraction of the treatment CTV and critical organs were delineated. The plan (PCT2) was created by reproducing the Plan PCT1 in the CT2 images and compared with PCT1. Bladder, Rectum and CTV percentage volume variation ranges from +28.6% to -34.3%, 38.4% to -14.9% and 8.5% to -15.2% respectively. Maximum dose variation in bladder was +17.1%, in rectum was up to +410% and in CTV was -13.0%. The dose to these structures varies independently with no strong correlation with the volume variation. Hence it is suggested that repeat CT and re-planning is mandatory before second fraction execution.

The Neuroimaging Studies in Children with Ventriculoperitoneal Shunt Complications: A 10 Years Descriptive Sudy in Tehran.

PubMed

Shahi, Mohammad Vafaee; Noorbakhsh, Samileh; Zarrabi, Vida; Nourozi, Banafsheh; Tahernia, Leila

2018-01-01

Any mismatch between the production and absorption of CSF results in hydrocephalus. In most cases, the selected choice of treatment is the ventriculoperitoneal shunt insertion. Although, the surgery could have complications such as infection, shunt malfunction, subdural hematoma, seizure and Shunt immigration; so, the early and proper detection of these complications could result in better prognosis. The aim of this study was to evaluate and compare the efficacy of CT scan, CSF analysis and X-ray radiography in detection of shunt complications and problems in shunt placement and further follow-up in hospitalized children. The medical records of children in Rasul Akram hospital in Tehran were reviewed retrospectively in the last 10 years, from 2006 to 2016. All data were recorded in the prepared form including the age, sex, shunt complication, CT scan and CSF characteristics. The total number of 95 patients were interfered in this study including 56 males (58.9%) and 39 females (41.1%). The mean age at the onset of complications were 2.8±2.2 years-old. The shunt obstruction (60%) and infection (25.3%) were the most common complications. The CT scan was able to detect 36.5% of shunt complications. The CT scan had the sensitivity and specificity of 50 and 87%, respectively in detection of shunt obstruction. The all cases of brain hematoma and hemorrhage were revealed by CT scan. On the other hand, the CT scan had 20% of sensitivity and 60% of specificity in the detection of shunt infection. The CSF evaluation in shunt infection revealed 92% hypoglycemia, 87.5% pleocytosis, and 62.5% positive CSF culture. CSF had the sensitivity, specificity, positive predictive value and negative predictive value of 92, 82, 63 and 97%, respectively. The patient's symptoms and signs were helpful in obtaining higher test accuracy. The CT scan was not a good sensitive and specific study in the detection of shunt obstruction and infection, but it was very accurate in detection of hemorrhage and hematoma. On the other hand, CSF evaluation was a reliable test in shunt infection disclosure.

Radiation Dose Reduction via Sinogram Affirmed Iterative Reconstruction and Automatic Tube Voltage Modulation (CARE kV) in Abdominal CT

PubMed Central

Shin, Hyun Joo; Lee, Young Han; Choi, Jin-Young; Park, Mi-Suk; Kim, Myeong-Jin; Kim, Ki Whang

2013-01-01

Objective To evaluate the feasibility of sinogram-affirmed iterative reconstruction (SAFIRE) and automated kV modulation (CARE kV) in reducing radiation dose without increasing image noise for abdominal CT examination. Materials and Methods This retrospective study included 77 patients who received CT imaging with an application of CARE kV with or without SAFIRE and who had comparable previous CT images obtained without CARE kV or SAFIRE, using the standard dose (i.e., reference mAs of 240) on an identical CT scanner and reconstructed with filtered back projection (FBP) within 1 year. Patients were divided into two groups: group A (33 patients, CT scanned with CARE kV); and group B (44 patients, scanned after reducing the reference mAs from 240 to 170 and applying both CARE kV and SAFIRE). CT number, image noise for four organs and radiation dose were compared among the two groups. Results Image noise increased after CARE kV application (p < 0.001) and significantly decreased as SAFIRE strength increased (p < 0.001). Image noise with reduced-mAs scan (170 mAs) in group B became similar to that of standard-dose FBP images after applying CARE kV and SAFIRE strengths of 3 or 4 when measured in the aorta, liver or muscle (p ≥ 0.108). Effective doses decreased by 19.4% and 41.3% for groups A and B, respectively (all, p < 0.001) after application of CARE kV with or without SAFIRE. Conclusion Combining CARE kV, reduction of mAs from 240 to 170 mAs and noise reduction by applying SAFIRE strength 3 or 4 reduced the radiation dose by 41.3% without increasing image noise compared with the standard-dose FBP images. PMID:24265563

Technical Note: Development and validation of an open data format for CT projection data.

PubMed

Chen, Baiyu; Duan, Xinhui; Yu, Zhicong; Leng, Shuai; Yu, Lifeng; McCollough, Cynthia

2015-12-01

Lack of access to projection data from patient CT scans is a major limitation for development and validation of new reconstruction algorithms. To meet this critical need, this work developed and validated a vendor-neutral format for CT projection data, which will further be employed to build a library of patient projection data for public access. A digital imaging and communication in medicine (DICOM)-like format was created for CT projection data (CT-PD), named the DICOM-CT-PD format. The format stores attenuation information in the DICOM image data block and stores parameters necessary for reconstruction in the DICOM header under various tags (51 tags to store the geometry and scan parameters and 9 tags to store patient information). To validate the accuracy and completeness of the new format, CT projection data from helical scans of the ACR CT accreditation phantom were acquired from two clinical CT scanners (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany and Discovery CT750 HD, GE Healthcare, Waukesha, WI). After decoding (by the authors for Siemens, by the manufacturer for GE), the projection data were converted to the DICOM-CT-PD format. Off-line CT reconstructions were performed by internal and external reconstruction researchers using only the information stored in the DICOM-CT-PD files and the DICOM-CT-PD field definitions. Compared with the commercially reconstructed CT images, the off-line reconstructed images created using the DICOM-CT-PD format are similar in terms of CT numbers (differences of 5 HU for the bone insert and -9 HU for the air insert), image noise (±1 HU), and low contrast detectability (6 mm rods visible in both). Because of different reconstruction approaches, slightly different in-plane and cross-plane high contrast spatial resolution were obtained compared to those reconstructed on the scanners (axial plane: GE off-line, 7 lp/cm; GE commercial, 7 lp/cm; Siemens off-line, 8 lp/cm; Siemens commercial, 7 lp/cm. Coronal plane: Siemens off-line, 6 lp/cm; Siemens commercial, 8 lp/cm). A vendor-neutral extended DICOM format has been developed that enables open sharing of CT projection data from third-generation CT scanners. Validation of the format showed that the geometric parameters and attenuation information in the DICOM-CT-PD file were correctly stored, could be retrieved with use of the provided instructions, and contained sufficient data for reconstruction of CT images that approximated those from the commercial scanner.

Full-Body CT Scans - What You Need to Know

MedlinePlus

... Medical Imaging Medical X-ray Imaging Full-Body CT Scans - What You Need to Know Share Tweet ... new service for health-conscious people: "Whole-body CT screening." This typically involves scanning the body from ...

CT-based attenuation and scatter correction compared with uniform attenuation correction in brain perfusion SPECT imaging for dementia

NASA Astrophysics Data System (ADS)

Gillen, Rebecca; Firbank, Michael J.; Lloyd, Jim; O'Brien, John T.

2015-09-01

This study investigated if the appearance and diagnostic accuracy of HMPAO brain perfusion SPECT images could be improved by using CT-based attenuation and scatter correction compared with the uniform attenuation correction method. A cohort of subjects who were clinically categorized as Alzheimer’s Disease (n=38 ), Dementia with Lewy Bodies (n=29 ) or healthy normal controls (n=30 ), underwent SPECT imaging with Tc-99m HMPAO and a separate CT scan. The SPECT images were processed using: (a) correction map derived from the subject’s CT scan or (b) the Chang uniform approximation for correction or (c) no attenuation correction. Images were visually inspected. The ratios between key regions of interest known to be affected or spared in each condition were calculated for each correction method, and the differences between these ratios were evaluated. The images produced using the different corrections were noted to be visually different. However, ROI analysis found similar statistically significant differences between control and dementia groups and between AD and DLB groups regardless of the correction map used. We did not identify an improvement in diagnostic accuracy in images which were corrected using CT-based attenuation and scatter correction, compared with those corrected using a uniform correction map.

Computed tomographic imaging of stapes implants.

PubMed

Warren, Frank M; Riggs, Sterling; Wiggins, Richard H

2008-08-01

Computed tomographic (CT) imaging of stapes prostheses is inaccurate. Clinical situations arise in which it would be helpful to determine the depth of penetration of a stapes prosthesis into the vestibule. The accuracy of CT imaging for this purpose has not been defined. This study was aimed to determine the accuracy of CT imaging to predict the depth of intrusion of stapes prostheses into the vestibule. The measurement of stapes prostheses by CT scan was compared with physical measurements in 8 cadaveric temporal bones. The depth of intrusion into the vestibule of the piston was underestimated in specimens with the fluoroplastic piston by a mean of 0.5 mm when compared with the measurements obtained in the temporal bones. The depth of penetration of the stainless steel implant was overestimated by 0.5 mm when compared with that in the temporal bone. The type of implant must be taken into consideration when estimating the depth of penetration into the vestibule using CT scanning because the imaging characteristics of the implanted materials differ. The position of fluoroplastic pistons cannot be accurately measured in the vestibule. Metallic implants are well visualized, and measurements exceeding 2.2 mm increase the suspicion of otolithic impingement. Special reconstructions along the length of the piston may be more accurate in estimating the position of stapes implants.

Co-registered perfusion SPECT/CT: utility for prediction of improved postoperative outcome in lung volume reduction surgery candidates.

PubMed

Takenaka, Daisuke; Ohno, Yoshiharu; Koyama, Hisanobu; Nogami, Munenobu; Onishi, Yumiko; Matsumoto, Keiko; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Sugimura, Kazuro

2010-06-01

To directly compare the capabilities of perfusion scan, SPECT, co-registered SPECT/CT, and quantitatively and qualitatively assessed MDCT (i.e. quantitative CT and qualitative CT) for predicting postoperative clinical outcome for lung volume reduction surgery (LVRS) candidates. Twenty-five consecutive candidates (19 men and six women, age range: 42-72 years) for LVRS underwent preoperative CT and perfusion scan with SPECT. Clinical outcome of LVRS for all subjects was also assessed by determining the difference between pre- and postoperative forced expiratory volume in 1s (FEV(1)) and 6-min walking distance (6MWD). All SPECT examinations were performed on a SPECT scanner, and co-registered to thin-section CT by using commercially available software. On planar imaging, SPECT and SPECT/CT, upper versus lower zone or lobe ratios (U/Ls) were calculated from regional uptakes between upper and lower lung fields in the operated lung. On quantitatively assessed CT, U/L for all subjects was assessed from regional functional lung volumes. On qualitatively assessed CT, planar imaging, SPECT and co-registered SPECT/CT, U/Ls were assessed with a 4-point visual scoring system. To compare capabilities of predicting clinical outcome, each U/L was statistically correlated with the corresponding clinical outcome. Significantly fair or moderate correlations were observed between quantitatively and qualitatively assessed U/Ls obtained with all four methods and clinical outcomes (-0.60

Are CT Scans a Satisfactory Substitute for the Follow-Up of RSA Migration Studies of Uncemented Cups? A Comparison of RSA Double Examinations and CT Datasets of 46 Total Hip Arthroplasties

PubMed Central

Zeleznik, Michael P.; Nilsson, Kjell G.; Olivecrona, Henrik

2017-01-01

As part of the 14-year follow-up of a prospectively randomized radiostereometry (RSA) study on uncemented cup fixation, two pairs of stereo radiographs and a CT scan of 46 hips were compared. Tantalum beads, inserted during the primary operation, were detected in the CT volume and the stereo radiographs and used to produce datasets of 3D coordinates. The limit of agreement between the combined CT and RSA datasets was calculated in the same way as the precision of the double RSA examination. The precision of RSA corresponding to the 99% confidence interval was 1.36°, 1.36°, and 0.60° for X-, Y-, and Z-rotation and 0.40, 0.17, and 0.37 mm for X-, Y-, and Z-translation. The limit of agreement between CT and RSA was 1.51°, 2.17°, and 1.05° for rotation and 0.59, 0.56, and 0.74 mm for translation. The differences between CT and RSA are close to the described normal 99% confidence interval for precision in RSA: 0.3° to 2° for rotation and 0.15 to 0.6 mm for translation. We conclude that measurements using CT and RSA are comparable and that CT can be used for migration studies for longitudinal evaluations of patients with RSA markers. PMID:28243598

Are CT Scans a Satisfactory Substitute for the Follow-Up of RSA Migration Studies of Uncemented Cups? A Comparison of RSA Double Examinations and CT Datasets of 46 Total Hip Arthroplasties.

PubMed

Otten, Volker; Maguire, Gerald Q; Noz, Marilyn E; Zeleznik, Michael P; Nilsson, Kjell G; Olivecrona, Henrik

2017-01-01

As part of the 14-year follow-up of a prospectively randomized radiostereometry (RSA) study on uncemented cup fixation, two pairs of stereo radiographs and a CT scan of 46 hips were compared. Tantalum beads, inserted during the primary operation, were detected in the CT volume and the stereo radiographs and used to produce datasets of 3D coordinates. The limit of agreement between the combined CT and RSA datasets was calculated in the same way as the precision of the double RSA examination. The precision of RSA corresponding to the 99% confidence interval was 1.36°, 1.36°, and 0.60° for X -, Y -, and Z -rotation and 0.40, 0.17, and 0.37 mm for X -, Y -, and Z -translation. The limit of agreement between CT and RSA was 1.51°, 2.17°, and 1.05° for rotation and 0.59, 0.56, and 0.74 mm for translation. The differences between CT and RSA are close to the described normal 99% confidence interval for precision in RSA: 0.3° to 2° for rotation and 0.15 to 0.6 mm for translation. We conclude that measurements using CT and RSA are comparable and that CT can be used for migration studies for longitudinal evaluations of patients with RSA markers.

A multicenter, randomized controlled trial of immediate total-body CT scanning in trauma patients (REACT-2)

PubMed Central

2012-01-01

Background Computed tomography (CT) scanning has become essential in the early diagnostic phase of trauma care because of its high diagnostic accuracy. The introduction of multi-slice CT scanners and infrastructural improvements made total-body CT scanning technically feasible and its usage is currently becoming common practice in several trauma centers. However, literature provides limited evidence whether immediate total-body CT leads to better clinical outcome then conventional radiographic imaging supplemented with selective CT scanning in trauma patients. The aim of the REACT-2 trial is to determine the value of immediate total-body CT scanning in trauma patients. Methods/design The REACT-2 trial is an international, multicenter randomized clinical trial. All participating trauma centers have a multi-slice CT scanner located in the trauma room or at the Emergency Department (ED). All adult, non-pregnant, severely injured trauma patients according to predefined criteria will be included. Patients in whom direct scanning will hamper necessary cardiopulmonary resuscitation or who require an immediate operation because of imminent death (both as judged by the trauma team leader) are excluded. Randomization will be computer assisted. The intervention group will receive a contrast-enhanced total-body CT scan (head to pelvis) during the primary survey. The control group will be evaluated according to local conventional trauma imaging protocols (based on ATLS guidelines) supplemented with selective CT scanning. Primary outcome will be in-hospital mortality. Secondary outcomes are differences in mortality and morbidity during the first year post trauma, several trauma work-up time intervals, radiation exposure, general health and quality of life at 6 and 12 months post trauma and cost-effectiveness. Discussion The REACT-2 trial is a multicenter randomized clinical trial that will provide evidence on the value of immediate total-body CT scanning during the primary survey of severely injured trauma patients. If immediate total-body CT scanning is found to be the best imaging strategy in severely injured trauma patients it could replace conventional imaging supplemented with CT in this specific group. Trial Registration ClinicalTrials.gov: (NCT01523626). PMID:22458247

A framelet-based iterative maximum-likelihood reconstruction algorithm for spectral CT

NASA Astrophysics Data System (ADS)

Wang, Yingmei; Wang, Ge; Mao, Shuwei; Cong, Wenxiang; Ji, Zhilong; Cai, Jian-Feng; Ye, Yangbo

2016-11-01

Standard computed tomography (CT) cannot reproduce spectral information of an object. Hardware solutions include dual-energy CT which scans the object twice in different x-ray energy levels, and energy-discriminative detectors which can separate lower and higher energy levels from a single x-ray scan. In this paper, we propose a software solution and give an iterative algorithm that reconstructs an image with spectral information from just one scan with a standard energy-integrating detector. The spectral information obtained can be used to produce color CT images, spectral curves of the attenuation coefficient μ (r,E) at points inside the object, and photoelectric images, which are all valuable imaging tools in cancerous diagnosis. Our software solution requires no change on hardware of a CT machine. With the Shepp-Logan phantom, we have found that although the photoelectric and Compton components were not perfectly reconstructed, their composite effect was very accurately reconstructed as compared to the ground truth and the dual-energy CT counterpart. This means that our proposed method has an intrinsic benefit in beam hardening correction and metal artifact reduction. The algorithm is based on a nonlinear polychromatic acquisition model for x-ray CT. The key technique is a sparse representation of iterations in a framelet system. Convergence of the algorithm is studied. This is believed to be the first application of framelet imaging tools to a nonlinear inverse problem.

Repeated irradiation from micro-computed tomography scanning at 2, 4 and 6 months of age does not induce damage to tibial bone microstructure in male and female CD-1 mice.

PubMed

Sacco, Sandra M; Saint, Caitlin; Longo, Amanda B; Wakefield, Charles B; Salmon, Phil L; LeBlanc, Paul J; Ward, Wendy E

2017-01-01

Long-term effects of repeated i n vivo micro-computed tomography (μCT) scanning at key stages of growth and bone development (ages 2, 4 and 6 months) on trabecular and cortical bone structure, as well as developmental patterns, have not been studied. We determined the effect of repetitive μCT scanning at age 2, 4 and 6 months on tibia bone structure of male and female CD-1 mice and characterized developmental changes. At 2, 4 and 6 months of age, right tibias were scanned using in vivo μCT (Skyscan 1176) at one of three doses of radiation per scan: 222, 261 or 460 mGy. Left tibias of the same mice were scanned only at 6 months to serve as non-irradiated controls to determine whether recurrent radiation exposure alters trabecular and cortical bone structure at the proximal tibia. In males, eccentricity was lower ( P <0.05) in irradiated compared with non-irradiated tibias (222 mGy group). Within each sex, all other structural outcomes were similar between irradiated and non-irradiated tibias regardless of dose. Trabecular bone loss occurred in all mice due to age while cortical development continued to age 6 months. In conclusion, repetitive μCT scans at various radiation doses did not damage trabecular or cortical bone structure of proximal tibia in male and female CD-1 mice. Moreover, scanning at 2, 4 and 6 months of age highlight the different developmental time course between trabecular and cortical bone. These scanning protocols can be used to investigate longitudinal responses of bone structures to an intervention.

Extravasation Risk Using Ultrasound-guided Peripheral Intravenous Catheters for Computed Tomography Contrast Administration.

PubMed

Rupp, Jordan D; Ferre, Robinson M; Boyd, Jeremy S; Dearing, Elizabeth; McNaughton, Candace D; Liu, Dandan; Jarrell, Kelli L; McWade, Conor M; Self, Wesley H

2016-08-01

Ultrasound-guided intravenous catheter (USGIV) insertion is increasingly being used for administration of intravenous (IV) contrast for computed tomography (CT) scans. The goal of this investigation was to evaluate the risk of contrast extravasation among patients receiving contrast through USGIV catheters. A retrospective observational study of adult patients who underwent a contrast-enhanced CT scan at a tertiary care emergency department during a recent 64-month period was conducted. The unadjusted prevalence of contrast extravasation was compared between patients with an USGIV and those with a standard peripheral IV inserted without ultrasound. Then, a two-stage sampling design was used to select a subset of the population for a multivariable logistic regression model evaluating USGIVs as a risk factor for extravasation while adjusting for potential confounders. In total, 40,143 patients underwent a contrasted CT scan, including 364 (0.9%) who had contrast administered through an USGIV. Unadjusted prevalence of extravasation was 3.6% for contrast administration through USGIVs and 0.3% for standard IVs (relative risk = 13.9, 95% confidence interval [CI] = 7.9 to 24.6). After potential confounders were adjusted for, CT contrast administered through USGIVs was associated with extravasation (adjusted odds ratio = 8.6, 95% CI = 4.6 to 16.2). No patients required surgical management for contrast extravasation; one patient in the standard IV group was admitted for observation due to extravasation. Patients who received contrast for a CT scan through an USGIV had a higher risk of extravasation than those who received contrast through a standard peripheral IV. Clinicians should consider this extravasation risk when weighing the risks and benefits of a contrast-enhanced CT scan in a patient with USGIV vascular access. © 2016 by the Society for Academic Emergency Medicine.

Extravasation Risk Using Ultrasound Guided Peripheral Intravenous Catheters for Computed Tomography Contrast Administration

PubMed Central

Rupp, Jordan D.; Ferre, Robinson M.; Boyd, Jeremy S.; Dearing, Elizabeth; McNaughton, Candace D.; Liu, Dandan; Jarrell, Kelli L.; McWade, Conor M.; Self, Wesley H.

2016-01-01

Objective Ultrasound guided intravenous catheter (USGIV) insertion is increasingly being used for administration of intravenous contrast for computed tomography (CT) scans. The goal of this investigation was to evaluate the risk of contrast extravasation among patients receiving contrast through USGIV catheters. Methods A retrospective observational study of adult patients who underwent a contrast-enhanced CT scan at a tertiary-care emergency department during a recent 64-month period was conducted. The unadjusted prevalence of contrast extravasation was compared between patients with an USGIV and those with a standard peripheral IV inserted without ultrasound. Then, a two-stage sampling design was used to select a subset of the population for a multivariable logistic regression model evaluating USGIVs as a risk factor for extravasation while adjusting for potential confounders. Results In total, 40,143 patients underwent a contrasted CT scan, including 364 (0.9%) who had contrast administered through an USGIV. Unadjusted prevalence of extravasation was 3.6% for contrast administration through USGIVs and 0.3% for standard IVs (relative risk: 13.9, 95% CI: 7.7 to 24.6). After adjustment for potential confounders, CT contrast administered through USGIVs was associated with extravasation (adjusted odds ratio: 8.6; 95% CI: 4.6, 16.2). No patients required surgical management for contrast extravasation; one patient in the standard IV group was admitted for observation due to extravasation. Conclusions Patients who received contrast for a CT scan through an USGIV had a higher risk of extravasation than those who received contrast through a standard peripheral IV. Clinicians should consider this extravasation risk when weighing the risks and benefits of a contrast-enhanced CT scan in a patient with USGIV vascular access. PMID:27151898

Cost effectiveness of the addition of a comprehensive CT scan to the abdomen and pelvis for the detection of cancer after unprovoked venous thromboembolism.

PubMed

Coyle, Kathryn; Carrier, Marc; Lazo-Langner, Alejandro; Shivakumar, Sudeep; Zarychanski, Ryan; Tagalakis, Vicky; Solymoss, Susan; Routhier, Nathalie; Douketis, James; Coyle, Douglas

2017-03-01

Unprovoked venous thromboembolism (VTE) can be the first manifestation of cancer. It is unclear if extensive screening for occult cancer including a comprehensive computed tomography (CT) scan of the abdomen/pelvis is cost-effective in this patient population. To assess the health care related costs, number of missed cancer cases and health related utility values of a limited screening strategy with and without the addition of a comprehensive CT scan of the abdomen/pelvis and to identify to what extent testing should be done in these circumstances to allow early detection of occult cancers. Cost effectiveness analysis using data that was collected alongside the SOME randomized controlled trial which compared an extensive occult cancer screening including a CT of the abdomen/pelvis to a more limited screening strategy in patients with a first unprovoked VTE, was used for the current analyses. Analyses were conducted with a one-year time horizon from a Canadian health care perspective. Primary analysis was based on complete cases, with sensitivity analysis using appropriate multiple imputation methods to account for missing data. Data from a total of 854 patients with a first unprovoked VTE were included in these analyses. The addition of a comprehensive CT scan was associated with higher costs ($551 CDN) with no improvement in utility values or number of missed cancers. Results were consistent when adopting multiple imputation methods. The addition of a comprehensive CT scan of the abdomen/pelvis for the screening of occult cancer in patients with unprovoked VTE is not cost effective, as it is both more costly and not more effective in detecting occult cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evidence of dose saving in routine CT practice using iterative reconstruction derived from a national diagnostic reference level survey.

PubMed

Thomas, P; Hayton, A; Beveridge, T; Marks, P; Wallace, A

2015-09-01

To assess the influence and significance of the use of iterative reconstruction (IR) algorithms on patient dose in CT in Australia. We examined survey data submitted to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) National Diagnostic Reference Level Service (NDRLS) during 2013 and 2014. We compared median survey dose metrics with categorization by scan region and use of IR. The use of IR results in a reduction in volume CT dose index of between 17% and 44% and a reduction in dose-length product of between 14% and 34% depending on the specific scan region. The reduction was highly significant (p < 0.001, Wilcoxon rank-sum test) for all six scan regions included in the NDRLS. Overall, 69% (806/1167) of surveys included in the analysis used IR. The use of IR in CT is achieving dose savings of 20-30% in routine practice in Australia. IR appears to be widely used by participants in the ARPANSA NDRLS with approximately 70% of surveys submitted employing this technique. This study examines the impact of the use of IR on patient dose in CT on a national scale.

CT Scanning in Identification of Sheep Cystic Echinococcosis

PubMed Central

Mao, Rui; Qi, Hongzhi; Pei, Lei; Hao, Jie; Dong, Jian; Jiang, Tao; Ainiwaer, Abudula; Shang, Ge; Xu, Lin; Shou, Xi; Zhang, Songan; Wu, Ge; Lu, Pengfei

2017-01-01

Objective We aim to determine the efficiency of CT in identification of cystic echinococcosis in sheep. Methods Fifty-three sheep with liver cysts confirmed by ultrasonography were subject to CT scan to evaluate the number, size, and type of the cysts in liver and lung, confirmed using necropsy. The correlation of numbers between liver cysts and lung cysts was calculated using Pearson analysis. Results Necropsy indicated a 98% consensus on size, location, number, and activity compared with CT scan. The viable cysts were 53.1% and 50.6% in the liver and lung, respectively. Among the cysts in liver, 35.5%, 9.5%, 5.7%, 10.2%, and 39.1% were Types CE1, CE2, CE3, CE4, and CE5, respectively. The cysts in the lungs, 17.4%, 26.9%, 12.1%, 11.6%, and 32.1%, were Types CE1, CE2, CE3, CE4, and CE5, respectively. A significant correlation was noticed between the number of cysts in liver and those in lung (R = 0.770, P < 0.001). Conclusions CT scan is a suitable tool in determining the size and type of cystic hydatid cysts in both liver and lung of sheep. A significant correlation was noticed between the numbers in liver and lung, indicating that lung infection was likely due to the expansion of liver cyst burden pressure. PMID:29082246

Poor symptom control is associated with reduced CT scan segmental airway lumen area in smokers with asthma.

PubMed

Thomson, Neil C; Chaudhuri, Rekha; Spears, Mark; Messow, Claudia-Martina; MacNee, William; Connell, Martin; Murchison, John T; Sproule, Michael; McSharry, Charles

2015-03-01

Cigarette smoking is associated with worse symptoms in asthma and abnormal segmental airways in healthy subjects. We tested the hypothesis that current symptom control in smokers with asthma is associated with altered segmental airway dimensions measured by CT scan. In 93 subjects with mild, moderate, and severe asthma (smokers and never smokers), we recorded Asthma Control Questionnaire-6 (ACQ-6) score, spirometry (FEV1; forced expiratory flow rate, midexpiratory phase [FEF(25%-75%)]), residual volume (RV), total lung capacity (TLC), and CT scan measures of the right bronchial (RB) and left bronchial (LB) segmental airway dimensions (wall thickness, mm; lumen area, mm²) in the RB3/LB3, RB6/LB6, and RB10/LB10 (smaller) airways. The CT scan segmental airway (RB10 and LB10) lumen area was reduced in smokers with asthma compared with never smokers with asthma; RB10, 16.6 mm² (interquartile range, 12.4-19.2 mm²) vs 19.6 mm² (14.7-24.2 mm²) (P = .01); LB10, 14.8 mm² (12.1-19.0 mm²) vs 19.9 mm² (14.5-25.0 mm²) (P = .003), particularly in severe disease, with no differences in wall thickness or in larger airway (RB3 and LB3) dimensions. In smokers with asthma, a reduced lumen area in fifth-generation airways (RB10 or LB10) was associated with poor symptom control (higher ACQ-6 score) (-0.463 [-0.666 to -0.196], P = .001, and -0.401 [-0.619 to -0.126], P = .007, respectively) and reduced postbronchodilator FEF(25%-75%) (0.521 [0.292-0.694], P < .001, and [0.471 [0.236-0.654], P = .001, respectively) and higher RV/TLC %. The CT scan segmental airway lumen area is reduced in smokers with asthma compared with never smokers with asthma, particularly in severe disease, and is associated with worse current symptom control and small airway dysfunction.

SU-F-J-117: Impact of Motion Artifacts On Image Quality and Accuracy of Tumor Motion Reconstruction in 4D CT-On-Rails and MV-CBCT Scans: A Phantom Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, T; Ma, C

Purpose: To compare and quantify respiratory motion artifacts in images from free breathing 4D-CT-on-Rails(CTOR) and those from MV-Cone-beam-CT(MVCB) and facilitate respiratory motion guided radiation therapy. Methods: 4D-CTOR: Siemens Somatom CT-on-Rails system with Anzai belt loaded with pressure sensor load cells. 4D scans were performed in helical mode, pitch 0.1, gantry rotation time 0.5s, 1.5mm slice thickness, 120kVp, 400 mAs. Normal and fast breathing (>12rpm) scanning protocols were investigated. Helical scan, AIP(average intensity projection) and MIP(maximum intensity projection) were generated from 4D-CTOR scans with amplitude sorting into 10 phases.MVCB: Siemens Artiste diamond view(1MV)MVCB was performed with 5MU thorax protocol with 60more » second of full rotation.Phantom: Anzai AZ-733V respiratory phantom. The settings were set to normal and resp. modes with repetition rates at 15 rpm and 10 rpm. Surgical clips, acrylic, wooden, rubber and lung density, total six mock-ups were scanned and compared in this study.Signal-to-noise ratio(SNR), contrast-to-noise ratio(CNR) and reconstructed motion volume were compared to different respiratory setups for the mock-ups. Results: Reconstructed motion volume was compared to the real object volume for the six test mock-ups. It shows that free breathing helical in all instances underestimates the object excursions largest to −67.4% and least −6.3%. Under normal breathing settings, MIP can predict very precise motion volume with minimum 0.4% and largest −13.9%. MVCB shows underestimate of the motion volume with −1.11% minimum and −18.0% maximum. With fast breathing, AIP provides bad representation of the object motion; however, the MIP can predict the motion volume with −2.0% to −11.4% underestimate. Conclusion: Respiratory motion guided radiation therapy requires good motion recording. This study shows that regular CTOR helical scans provides bad guidance, 4D CTOR AIP cannot represent the fast breathing pattern, MIP can represent the best motion volume, MVCBCT can only be used for normal breathing with acceptable uncertainties.« less

3D ECG- and respiratory-gated non-contrast-enhanced (CE) perfusion MRI for postoperative lung function prediction in non-small-cell lung cancer patients: A comparison with thin-section quantitative computed tomography, dynamic CE-perfusion MRI, and perfusion scan.

PubMed

Ohno, Yoshiharu; Seki, Shinichiro; Koyama, Hisanobu; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Takenaka, Daisuke; Kassai, Yoshimori; Yui, Masao; Sugimura, Kazuro

2015-08-01

To compare predictive capabilities of non-contrast-enhanced (CE)- and dynamic CE-perfusion MRIs, thin-section multidetector computed tomography (CT) (MDCT), and perfusion scan for postoperative lung function in non-small cell lung cancer (NSCLC) patients. Sixty consecutive pathologically diagnosed NSCLC patients were included and prospectively underwent thin-section MDCT, non-CE-, and dynamic CE-perfusion MRIs and perfusion scan, and had their pre- and postoperative forced expiratory volume in one second (FEV1 ) measured. Postoperative percent FEV1 (po%FEV1 ) was then predicted from the fractional lung volume determined on semiquantitatively assessed non-CE- and dynamic CE-perfusion MRIs, from the functional lung volumes determined on quantitative CT, from the number of segments observed on qualitative CT, and from uptakes detected on perfusion scans within total and resected lungs. Predicted po%FEV1 s were then correlated with actual po%FEV1 s, which were %FEV1 s measured postoperatively. The limits of agreement were also determined. All predicted po%FEV1 s showed significant correlation (0.73 ≤ r ≤ 0.93, P < 0.0001) and limits of agreement with actual po%FEV1 (non-CE-perfusion MRI: 0.3 ± 10.0%, dynamic CE-perfusion MRI: 1.0 ± 10.8%, perfusion scan: 2.2 ± 14.1%, quantitative CT: 1.2 ± 9.0%, qualitative CT: 1.5 ± 10.2%). Non-CE-perfusion MRI may be able to predict postoperative lung function more accurately than qualitatively assessed MDCT and perfusion scan. © 2014 Wiley Periodicals, Inc.

Cervix Motion in 50 Cervical Cancer Patients Assessed by Daily Cone Beam Computed Tomographic Imaging of a New Type of Marker

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langerak, Thomas, E-mail: t.langerak@erasmusmc.nl; Mens, Jan Willem; Quint, Sandra

Purpose: To evaluate a new type of marker and a new method of marker implantation and to assess interfraction cervix motion for a large population of patients with locally advanced cervical cancer by daily cone beam computed tomographic (CBCT) imaging. Methods and Materials: We investigated the position of markers in 50 patients treated in prone position during at least 23 fractions. To reduce streaking artifacts in the planning CT scan, a new type of polymeric marker was used and compared with conventional gold markers. In addition, a new method of implantation was used in an attempt to reduce marker loss.more » In each fraction, a CT scan was acquired before dose delivery and aligned to the bony anatomy of the planning CT scan, simulating the clinical setup protocol. First, sufficient visibility of the markers was verified. Then, systematic and random displacement of the marker centroids was recorded and analyzed in 3 directions with regard to the planning CT and the first CBCT (to evaluate the presence of a vaginal catheter in the planning CT). Streaking artifacts were quantified with the standard deviation of the mean squared intensity difference in a radius around the marker. Results: Marker loss was minimal during treatment: in only 3 of the 50 patients 1 marker was lost. Streaking artifacts for the new markers were reduced compared with conventional gold markers. For the planning CT, M/Σ/σ were 0.4/3.4/2.2 mm, 1.0/5.5/4.5 mm, and −3.9/5.1/3.6 mm for the left-right, anterior-posterior, and cranial-caudal directions, respectively. With regard to the first CBCT scan, M/Σ/σ were 0.8/2.8/2.1, 0.6/4.4/4.4, and −1.3/4.5/3.6 mm. Conclusions: A new type of marker and implantation method was shown to have significantly reduced marker loss and streaking artifacts compared with gold fiducial markers. The recorded marker displacement confirms results reported in the existing literature but for a larger dataset.« less

TU-C-12A-12: Differentiating Bone Lesions and Degenerative Joint Disease in NaF PET/CT Scans Using Machine Learning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perk, T; Bradshaw, T; Muzahir, S

2014-06-15

Purpose: [F-18]NaF PET can be used to image bone metastases; however, tracer uptake in degenerative joint disease (DJD) often appears similar to metastases. This study aims to develop and compare different machine learning algorithms to automatically identify regions of [F-18]NaF scans that correspond to DJD. Methods: 10 metastatic prostate cancer patients received whole body [F-18]NaF PET/CT scans prior to treatment. Image segmentation resulted in 852 ROIs, 69 of which were identified by a nuclear medicine physician as DJD. For all ROIs, various PET and CT textural features were computed. ROIs were divided into training and testing sets used to trainmore » eight different machine learning classifiers. Classifiers were evaluated based on receiver operating characteristics area under the curve (AUC), sensitivity, specificity, and positive predictive value (PPV). We also assessed the added value of including CT features in addition to PET features for training classifiers. Results: The training set consisted of 37 DJD ROIs with 475 non-DJD ROIs, and the testing set consisted of 32 DJD ROIs with 308 non-DJD ROIs. Of all classifiers, generalized linear models (GLM), decision forests (DF), and support vector machines (SVM) had the best performance. AUCs of GLM (0.929), DF (0.921), and SVM (0.889) were significantly higher than the other models (p<0.001). GLM and DF, overall, had the best sensitivity, specificity, and PPV, and gave a significantly better performance (p<0.01) than all other models. PET/CT GLM classifiers had higher AUC than just PET or just CT. GLMs built using PET/CT information had superior or comparable sensitivities, specificities and PPVs to just PET or just CT. Conclusion: Machine learning algorithms trained with PET/CT features were able to identify some cases of DJD. GLM outperformed the other classification algorithms. Using PET and CT information together was shown to be superior to using PET or CT features alone. Research supported by the Prostate Cancer Foundation.« less

TH-CD-202-04: Evaluation of Virtual Non-Contrast Images From a Novel Split-Filter Dual-Energy CT Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, J; Szczykutowicz, T; Bayouth, J

Purpose: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. Methods: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7–20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between themore » acquisition of low- and high-energy data. Additionally, VNC images were generated with the sequential-scan technique (80 and 140kVp) for comparison. CT number accuracy was evaluated for all materials at 15, 25, and 35mGy CTDIvol. Results: The spectral separation was greater for the sequential-scan technique than the split-filter technique with dual-energy ratios of 2.18 and 1.26, respectively. Both techniques successfully removed iodine contrast, resulting in mean CT numbers within 60HU of 0HU (split-filter) and 40HU of 0HU (sequential-scan) for all iodine concentrations. Additionally, for iodine vials of varying diameter (2–20 mm) with the same concentration (9.9 mg I /mL), the system accurately detected iodine for all sizes investigated. Both dual-energy techniques resulted in reduced CT numbers for bone materials (by >400HU for the densest bone). Increasing the imaging dose did not improve the CT number accuracy for bone in VNC images. Conclusion: VNC images from the split-filter technique successfully removed iodine contrast. These results demonstrate a potential for improving dose calculation accuracy and reducing patient imaging dose, while achieving superior temporal resolution in comparison sequential scans. For both techniques, inaccuracies in CT numbers for bone materials necessitate consideration for radiation therapy treatment planning.« less

A Prospective Study Comparing 99mTc-Hydroxyethylene-Diphosphonate Planar Bone Scintigraphy and Whole-Body SPECT/CT with 18F-Fluoride PET/CT and 18F-Fluoride PET/MRI for Diagnosing Bone Metastases.

PubMed

Löfgren, Johan; Mortensen, Jann; Rasmussen, Sine H; Madsen, Claus; Loft, Annika; Hansen, Adam E; Oturai, Peter; Jensen, Karl Erik; Mørk, Mette Louise; Reichkendler, Michala; Højgaard, Liselotte; Fischer, Barbara M

2017-11-01

We prospectively evaluated and compared the diagnostic performance of 99m Tc-hydroxyethylene-diphosphonate ( 99m Tc-HDP) planar bone scintigraphy (pBS), 99m Tc-HDP SPECT/CT, 18 F-NaF PET/CT, and 18 F-NaF PET/MRI for the detection of bone metastases. Methods: One hundred seventeen patients with histologically proven malignancy referred for clinical pBS were prospectively enrolled. pBS and whole-body SPECT/CT were performed followed by 18 F-NaF PET/CT within 9 d. 18 F-NaF PET/MRI was also performed in 46 patients. Results: Bone metastases were confirmed in 16 patients and excluded in 101, which was lower than expected. The number of equivocal scans was significantly higher for pBS than for SPECT/CT and PET/CT (18 vs. 5 and 6, respectively; P = 0.004 and 0.01, respectively). When equivocal readings were excluded, no statistically significant difference in sensitivity, specificity, positive predictive value, negative predictive value, or overall accuracy were found when comparing the different imaging techniques. In the per-patient analysis, equivocal scans were either assumed positive for metastases ("pessimistic analysis") or assumed negative for metastases ("optimistic analysis"). The percentages of misdiagnosed patients for the pessimistic analysis were 21%, 15%, 9%, and 7% for pBS, SPECT/CT, PET/CT, and PET/MRI, respectively. Corresponding figures for the optimistic analysis were 9%, 12%, 5%, and 7%. In those patients identified as having bone metastases according to the reference standard, SPECT/CT, 18 F-NaF PET/CT, and PET/MRI detected additional lesions compared with pBS in 31%, 63%, and 71%, respectively. Conclusion: 18 F-NaF PET/CT and whole-body SPECT/CT resulted in a significant reduction of equivocal readings compared with pBS, which implies an improved diagnostic confidence. However, the clinical benefit of using, for example, 18 F-NaF PET/CT or PET/MRI as compared with SPECT/CT and pBS in this patient population with a relatively low prevalence of bone metastases (14%) is likely limited. This conclusion is influenced by the low prevalence of patients with osseous metastases. There may well be significant differences in the sensitivity of SPECT/CT, PET/CT, and PET/MRI compared with pBS, but a larger patient population or a patient population with a higher prevalence of bone metastases would have to be studied to demonstrate this. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Accuracy and reliability of different cone beam computed tomography (CBCT) devices for structural analysis of alveolar bone in comparison with multislice CT and micro-CT.

PubMed

Van Dessel, Jeroen; Nicolielo, Laura Ferreira Pinheiro; Huang, Yan; Coudyzer, Walter; Salmon, Benjamin; Lambrichts, Ivo; Jacobs, Reinhilde

The aim of this study was to assess whether cone beam computed tomography (CBCT) may be used for clinically reliable alveolar bone quality assessment in comparison to its clinical alternatives, multislice computed tomography and the gold standard (micro-CT). Six dentate mandibular bone samples were scanned with seven CBCT devices (ProMax 3D Max, NewTom GiANO, Cranex 3D, 3D Accuitomo 170, Carestream 9300, Scanora 3D, I-CAT Next generation), one micro-CT scanner (SkyScan 1174) and one MSCT machine (Somatom Definition Flash) using two protocols (standard and high-resolution). MSCT and CBCT images were automatically spatially aligned on the micro-CT scan of the corresponding sample. A volume of interest was manually delineated on the micro-CT image and overlaid on the other scanning devices. Alveolar bone structures were automatically extracted using the adaptive thresholding algorithm. Based on the resulting binary images, an automatic 3D morphometric quantification was performed in a CT-Analyser (Bruker, Kontich, Belgium). The reliability and measurement errors were calculated for each modality compared to the gold standard micro-CT. Both MSCT and CBCT were associated with a clinically and statistically (P <0.05) significant measurement error. Bone quantity-related morphometric indices (bone volume fraction 8.41% min to 17.90% max, bone surface density -0.47 mm-1 min to 0.16 mm-1 max and trabecular thickness 0.15 mm min to 0.31 mm max) were significantly (P <0.05) overestimated, resulting in significantly (P <0.05) closer trabecular pores (total porosity percentage -8.41% min to -17.90% max and fractal dimension 0.08 min to 0.17 max) in all scanners compared to micro-CT. However, the structural pattern of the alveolar bone remained similar compared to that of the micro-CT for the ProMax 3D Max, NewTom GiANO, Cranex 3D, 3D Accuitomo 170 and Carestream 9300. On the other hand, the Scanora 3D, i-CAT Next Generation, standard and high-resolution MSCT displayed an overrated bone quantity and aberrant structural pattern compared to other scanning devices. The calculation of morphometric indices had an overall high reliability (intraclass correlation coefficient [ICC] 0.62 min to 0.99 max), except for the i-CAT Next Generation CBCT (ICC 0.26 min to 0.86 max) and standard resolution MSCT (ICC 0.10 min to 0.62 max). This study demonstrated that most CBCT machines may be able to quantitatively assess alveolar bone quality, with a level of accuracy and reliability that approaches micro-CT. One may therefore propose to extrapolate this to clinical CBCT imaging, certainly when there is a need for implant rehabilitation in dentate jaw bones. Conflict-of-interest statement: There is no conflict of interest to declare. Fellowship support was received from Research Foundation Flanders (FWO) from the Belgian government and from the Coordination for the Improvement of Higher Education Personnel (CAPES) programme, Science without Borders, from the Brazilian government.

Functional imaging in differentiating bronchial masses: an initial experience with a combination of (18)F-FDG PET-CT scan and (68)Ga DOTA-TOC PET-CT scan.

PubMed

Kumar, Arvind; Jindal, Tarun; Dutta, Roman; Kumar, Rakesh

2009-10-01

To evaluate the role of combination of (18)F-FDG PET-CT scan and (68)Ga DOTA-TOC PET-CT scan in differentiating bronchial tumors observed in contrast enhanced computed tomography scan of chest. Prospective observational study. Place of study: All India Institute of Medical Sciences, New Delhi, India. 7 patients with bronchial mass detected in computed tomography scan of the chest were included in this study. All patients underwent (18)F-FDG PET-CT scan, (68)Ga DOTA-TOC PET-CT scan and fiberoptic bronchoscope guided biopsy followed by definitive surgical excision. The results of functional imaging studies were analyzed and the results are correlated with the final histopathology of the tumor. Histopathological examination of 7 bronchial masses revealed carcinoid tumors (2 typical, 1 atypical), inflammatory myofibroblastic tumor (1), mucoepidermoid carcinoma (1), hamartoma (1), and synovial cell sarcoma (1). The typical carcinoids had mild (18)F-FDG uptake and high (68)Ga DOTA-TOC uptake. Atypical carcinoid had moderate uptake of (18)F-FDG and high (68)Ga DOTA-TOC uptake. Inflammatory myofibroblastic tumor showed high uptake of (18)F-FDG and no uptake of (68)Ga DOTA-TOC. Mucoepidermoid carcinoma showed mild (18)F-FDG uptake and no (68)Ga DOTA-TOC uptake. Hamartoma showed no uptake on either scans. Synovial cell sarcoma showed moderate (18)F-FDG uptake and mild focal (68)Ga DOTA-TOC uptake. This initial experience with the combined use of (18)F-FDG and (68)Ga DOTA-TOC PET-CT scan reveals different uptake patterns in various bronchial tumors. Bronchoscopic biopsy will continue to be the gold standard; however, the interesting observations made in this study merits further evaluation of the utility of the combination of (18)F-FDG PET-CT scan and (68)Ga DOTA-TOC PET-CT scan in larger number of patients with bronchial masses.

Achievement of trifecta in minimally invasive partial nephrectomy correlates with functional preservation of operated kidney: a multi-institutional assessment using MAG3 renal scan.

PubMed

Zargar, Homayoun; Porpiglia, Francesco; Porter, James; Quarto, Giuseppe; Perdona, Sisto; Bertolo, Riccardo; Autorino, Riccardo; Kaouk, Jihad H

2016-07-01

To validate and compare the values of "MIC" and "trifecta" as predictors of operated kidney functional preservation in a multi-institutional cohort of patients undergoing minimally invasive PN. We retrospectively reviewed records of consecutive cases of minimally invasive PN performed for cT1 renal masses in 4 centers from 2009 to 2013. Inclusion criteria consisted of availability of a renal scan obtained within 2 weeks prior to surgery and follow-up renal scan 3-6 months after the surgery. The primary endpoint of the study was to compare the degree of ipsilateral renal function preservation assessed by MAG3 renal scan in relation to achievement of MIC and trifecta. Total of 351 patients met our inclusion criteria. The rates of trifecta achievement for cT1a and cT1b tumors were 78.9 and 60.6 %, respectively. The rate of MIC achievement for cT1a tumors and cT1b tumors was 60.3 and 31.7 %, respectively. On multivariable linear regression model, only the degree of tumor complexity assessed by R.E.N.A.L nephrometry score [coefficient B -1.8 (-2.7, -0.9); p < 0.0001] and the achievement of trifecta [coefficient B 6.1 (2.4,9.8); p = 0.014] or MIC (coefficient B 7.2 (3.8,0.6); p < 0.0001) were significant clinical factors predicting ipsilateral split function preservation. Achievement of both MIC and "trifecta" is associated with higher proportion of split renal function preservation for cT1 tumors after minimally invasive PN. Thus, these outcome measures can be regarded not only as markers of surgical quality, but also as reliable surrogates for predicting functional outcome in the operated kidney.

In-Plane Shielding for CT: Effect of Off-Centering, Automatic Exposure Control and Shield-to-Surface Distance

PubMed Central

Dang, Pragya; Singh, Sarabjeet; Saini, Sanjay; Shepard, Jo-Anne O.

2009-01-01

Objective To assess effects of off-centering, automatic exposure control, and padding on attenuation values, noise, and radiation dose when using in-plane bismuth-based shields for CT scanning. Materials and Methods A 30 cm anthropomorphic chest phantom was scanned on a 64-multidetector CT, with the center of the phantom aligned to the gantry isocenter. Scanning was repeated after placing a bismuth breast shield on the anterior surface with no gap and with 1, 2, and 6 cm of padding between the shield and the phantom surface. The "shielded" phantom was also scanned with combined modulation and off-centering of the phantom at 2 cm, 4 cm and 6 cm below the gantry isocenter. CT numbers, noise, and surface radiation dose were measured. The data were analyzed using an analysis of variance. Results The in-plane shield was not associated with any significant increment for the surface dose or CT dose index volume, which was achieved by comparing the radiation dose measured by combined modulation technique to the fixed mAs (p > 0.05). Irrespective of the gap or the surface CT numbers, surface noise increased to a larger extent compared to Hounsfield unit (HU) (0-6 cm, 26-55%) and noise (0-6 cm, 30-40%) in the center. With off-centering, in-plane shielding devices are associated with less dose savings, although dose reduction was still higher than in the absence of shielding (0 cm off-center, 90% dose reduction; 2 cm, 61%) (p < 0.0001). Streak artifacts were noted at 0 cm and 1 cm gaps but not at 2 cm and 6 cm gaps of shielding to the surface distances. Conclusion In-plane shields are associated with greater image noise, artifactually increased attenuation values, and streak artifacts. However, shields reduce radiation dose regardless of the extent of off-centering. Automatic exposure control did not increase radiation dose when using a shield. PMID:19270862

[Performance evaluation of CT automatic exposure control on fast dual spiral scan].

PubMed

Niwa, Shinji; Hara, Takanori; Kato, Hideki; Wada, Yoichi

2014-11-01

The performance of individual computed tomography automatic exposure control (CT-AEC) is very important for radiation dose reduction and image quality equalization in CT examinations. The purpose of this study was to evaluate the performance of CT-AEC in conventional pitch mode (Normal spiral) and fast dual spiral scan (Flash spiral) in a 128-slice dual-source CT scanner. To evaluate the response properties of CT-AEC in the 128-slice DSCT scanner, a chest phantom was placed on the patient table and was fixed at the center of the field of view (FOV). The phantom scan was performed using Normal spiral and Flash spiral scanning. We measured the effective tube current time product (Eff. mAs) of simulated organs in the chest phantom along the longitudinal (z) direction, and the dose dependence (distribution) of in-plane locations for the respective scan modes was also evaluated by using a 100-mm-long pencil-type ionization chamber. The dose length product (DLP) was evaluated using the value displayed on the console after scanning. It was revealed that the response properties of CT-AEC in Normal spiral scanning depend on the respective pitches and Flash spiral scanning is independent of the respective pitches. In-plane radiation dose of Flash spiral was lower than that of Normal spiral. The DLP values showed a difference of approximately 1.7 times at the maximum. The results of our experiments provide information for adjustments for appropriate scanning parameters using CT-AEC in a 128-slice DSCT scanner.

Automated lung volumetry from routine thoracic CT scans: how reliable is the result?

PubMed

Haas, Matthias; Hamm, Bernd; Niehues, Stefan M

2014-05-01

Today, lung volumes can be easily calculated from chest computed tomography (CT) scans. Modern postprocessing workstations allow automated volume measurement of data sets acquired. However, there are challenges in the use of lung volume as an indicator of pulmonary disease when it is obtained from routine CT. Intra-individual variation and methodologic aspects have to be considered. Our goal was to assess the reliability of volumetric measurements in routine CT lung scans. Forty adult cancer patients whose lungs were unaffected by the disease underwent routine chest CT scans in 3-month intervals, resulting in a total number of 302 chest CT scans. Lung volume was calculated by automatic volumetry software. On average of 7.2 CT scans were successfully evaluable per patient (range 2-15). Intra-individual changes were assessed. In the set of patients investigated, lung volume was approximately normally distributed, with a mean of 5283 cm(3) (standard deviation = 947 cm(3), skewness = -0.34, and curtosis = 0.16). Between different scans in one and the same patient the median intra-individual standard deviation in lung volume was 853 cm(3) (16% of the mean lung volume). Automatic lung segmentation of routine chest CT scans allows a technically stable estimation of lung volume. However, substantial intra-individual variations have to be considered. A median intra-individual deviation of 16% in lung volume between different routine scans was found. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

Diagnostic Value of 68Ga PSMA-11 PET/CT Imaging of Brain Tumors-Preliminary Analysis.

PubMed

Sasikumar, Arun; Joy, Ajith; Pillai, M R A; Nanabala, Raviteja; Anees K, Muhammed; Jayaprakash, P G; Madhavan, Jayaprakash; Nair, Suresh

2017-01-01

To evaluate the feasibility of using Ga PSMA-11 PET/CT for imaging brain lesions and its comparison with F-FDG. Ten patients with brain lesions were included in the study. Five patients were treated cases of glioblastoma with suspected recurrence. F-FDG and Ga PSMA-11 brain scans were done for these patients. Five patients were sent for assessing the nature (primary lesion/metastasis) of space occupying lesion in brain. They underwent whole body F-FDG PET/CT scan and a primary site elsewhere in the body was ruled out. Subsequently they underwent Ga PSMA-11 brain PET/CT imaging. Target to background ratios (TBR) for the brain lesions were calculated using contralateral cerebellar uptake as background. In five treated cases of glioblastoma with suspected recurrence the findings of Ga PSMA-11 PET/CT showed good correlation with that of F-FDG PET/CT scan. Compared to the F-FDG, Ga PSMA-11 PET/CT showed better visualization of the recurrent lesion (presence/absence) owing to its significantly high TBR. Among the five cases evaluated for lesion characterization glioma and atypical meningioma patients showed higher SUVmax in the lesion with Ga PSMA-11 than with F-FDG and converse in cases of lymphoma. TBR was better with Ga PSMA PET/CT in all cases. Ga PSMA-11 PET/CT brain imaging is a potentially useful imaging tool in the evaluation of brain lesions. Absence of physiological uptake of Ga PSMA-11 in the normal brain parenchyma results in high TBR values and consequently better visualization of metabolically active disease in brain.

Ventricular Geometry From Non-contrast Non-ECG-gated CT Scans: An Imaging Marker of Cardiopulmonary Disease in Smokers.

PubMed

Rahaghi, Farbod N; Vegas-Sanchez-Ferrero, Gonzalo; Minhas, Jasleen K; Come, Carolyn E; De La Bruere, Isaac; Wells, James M; González, Germán; Bhatt, Surya P; Fenster, Brett E; Diaz, Alejandro A; Kohli, Puja; Ross, James C; Lynch, David A; Dransfield, Mark T; Bowler, Russel P; Ledesma-Carbayo, Maria J; San José Estépar, Raúl; Washko, George R

2017-05-01

Imaging-based assessment of cardiovascular structure and function provides clinically relevant information in smokers. Non-cardiac-gated thoracic computed tomographic (CT) scanning is increasingly leveraged for clinical care and lung cancer screening. We sought to determine if more comprehensive measures of ventricular geometry could be obtained from CT using an atlas-based surface model of the heart. Subcohorts of 24 subjects with cardiac magnetic resonance imaging (MRI) and 262 subjects with echocardiography were identified from COPDGene, a longitudinal observational study of smokers. A surface model of the heart was manually initialized, and then automatically optimized to fit the epicardium for each CT. Estimates of right and left ventricular (RV and LV) volume and free-wall curvature were then calculated and compared to structural and functional metrics obtained from MRI and echocardiograms. CT measures of RV dimension and curvature correlated with similar measures obtained using MRI. RV and LV volume obtained from CT inversely correlated with echocardiogram-based estimates of RV systolic pressure using tricuspid regurgitation jet velocity and LV ejection fraction respectively. Patients with evidence of RV or LV dysfunction on echocardiogram had larger RV and LV dimensions on CT. Logistic regression models based on demographics and ventricular measures from CT had an area under the curve of >0.7 for the prediction of elevated right ventricular systolic pressure and ventricular failure. These data suggest that non-cardiac-gated, non-contrast-enhanced thoracic CT scanning may provide insight into cardiac structure and function in smokers. Copyright © 2017. Published by Elsevier Inc.

SU-E-J-120: Comparing 4D CT Computed Ventilation to Lung Function Measured with Hyperpolarized Xenon-129 MRI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neal, B; Chen, Q

2015-06-15

Purpose: To correlate ventilation parameters computed from 4D CT to ventilation, profusion, and gas exchange measured with hyperpolarized Xenon-129 MRI for a set of lung cancer patients. Methods: Hyperpolarized Xe-129 MRI lung scans were acquired for lung cancer patients, before and after radiation therapy, measuring ventilation, perfusion, and gas exchange. In the standard clinical workflow, these patients also received 4D CT scans before treatment. Ventilation was computed from 4D CT using deformable image registration (DIR). All phases of the 4D CT scan were registered using a B-spline deformable registration. Ventilation at the voxel level was then computed for each phasemore » based on a Jacobian volume expansion metric, yielding phase sorted ventilation images. Ventilation based upon 4D CT and Xe-129 MRI were co-registered, allowing qualitative visual comparison and qualitative comparison via the Pearson correlation coefficient. Results: Analysis shows a weak correlation between hyperpolarized Xe-129 MRI and 4D CT DIR ventilation, with a Pearson correlation coefficient of 0.17 to 0.22. Further work will refine the DIR parameters to optimize the correlation. The weak correlation could be due to the limitations of 4D CT, registration algorithms, or the Xe-129 MRI imaging. Continued development will refine parameters to optimize correlation. Conclusion: Current analysis yields a minimal correlation between 4D CT DIR and Xe-129 MRI ventilation. Funding provided by the 2014 George Amorino Pilot Grant in Radiation Oncology at the University of Virginia.« less

Sarcoidosis: correlation of pulmonary parenchymal pattern at CT with results of pulmonary function tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bergin, C.J.; Bell, D.Y.; Coblentz, C.L.

1989-06-01

The appearances of the lungs on radiographs and computed tomographic (CT) scans were correlated with degree of uptake on gallium scans and results of pulmonary function tests (PFTs) in 27 patients with sarcoidosis. CT scans were evaluated both qualitatively and quantitatively. Patients were divided into five categories on the basis of the pattern of abnormality at CT: 1 = normal (n = 4); 2 = segmental air-space disease (n = 4); 3 = spherical (alveolar) masslike opacities (n = 4); 4 = multiple, discrete, small nodules (n = 6); and 5 = distortion of parenchymal structures (fibrotic end-stage sarcoidosis) (nmore » = 9). The percentage of the volume judged to be abnormal (CT grade) was correlated with PFT results for each CT and radiographic category. CT grades were also correlated with gallium scanning results and percentage of lymphocytes recovered from bronchoalveolar lavage (BAL). Patients in CT categories 1 and 2 had normal lung function, those in category 3 had mild functional impairment, and those in categories 4 and 5 showed moderate to severe dysfunction. The overall CT grade correlated well with PFT results expressed as a percentage of the predicted value. In five patients, CT scans showed extensive parenchymal disease not seen on radiographs. CT grades did not correlate with the results of gallium scanning or BAL lymphocytes. The authors conclude that patterns of parenchymal sarcoidosis seen at CT correlate with the PFT results and can be used to indicate respiratory impairment.« less

Optimization of dose and image quality in adult and pediatric computed tomography scans

NASA Astrophysics Data System (ADS)

Chang, Kwo-Ping; Hsu, Tzu-Kun; Lin, Wei-Ting; Hsu, Wen-Lin

2017-11-01

Exploration to maximize CT image and reduce radiation dose was conducted while controlling for multiple factors. The kVp, mAs, and iteration reconstruction (IR), affect the CT image quality and radiation dose absorbed. The optimal protocols (kVp, mAs, IR) are derived by figure of merit (FOM) based on CT image quality (CNR) and CT dose index (CTDIvol). CT image quality metrics such as CT number accuracy, SNR, low contrast materials' CNR and line pair resolution were also analyzed as auxiliary assessments. CT protocols were carried out with an ACR accreditation phantom and a five-year-old pediatric head phantom. The threshold values of the adult CT scan parameters, 100 kVp and 150 mAs, were determined from the CT number test and line pairs in ACR phantom module 1and module 4 respectively. The findings of this study suggest that the optimal scanning parameters for adults be set at 100 kVp and 150-250 mAs. However, for improved low- contrast resolution, 120 kVp and 150-250 mAs are optimal. Optimal settings for pediatric head CT scan were 80 kVp/50 mAs, for maxillary sinus and brain stem, while 80 kVp /300 mAs for temporal bone. SNR is not reliable as the independent image parameter nor the metric for determining optimal CT scan parameters. The iteration reconstruction (IR) approach is strongly recommended for both adult and pediatric CT scanning as it markedly improves image quality without affecting radiation dose.

Relative plan robustness of step-and-shoot vs rotational intensity–modulated radiotherapy on repeat computed tomographic simulation for weight loss in head and neck cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomson, David J.; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester; Beasley, William J.

Introduction: Interfractional anatomical alterations may have a differential effect on the dose delivered by step-and-shoot intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). The increased degrees of freedom afforded by rotational delivery may increase plan robustness (measured by change in target volume coverage and doses to organs at risk [OARs]). However, this has not been evaluated for head and neck cancer. Materials and methods: A total of 10 patients who required repeat computed tomography (CT) simulation and replanning during head and neck IMRT were included. Step-and-shoot IMRT and VMAT plans were generated from the original planning scan. The initial andmore » second CT simulation scans were fused and targets/OAR contours transferred, reviewed, and modified. The plans were applied to the second CT scan and doses recalculated without repeat optimization. Differences between step-and-shoot IMRT and VMAT for change in target volume coverage and doses to OARs between first and second CT scans were compared by Wilcoxon signed rank test. Results: There were clinically relevant dosimetric changes between the first and the second CT scans for both the techniques (reduction in mean D{sub 95%} for PTV2 and PTV3, D{sub min} for CTV2 and CTV3, and increased mean doses to the parotid glands). However, there were no significant differences between step-and-shoot IMRT and VMAT for change in any target coverage parameter (including D{sub 95%} for PTV2 and PTV3 and D{sub min} for CTV2 and CTV3) or dose to any OARs (including parotid glands) between the first and the second CT scans. Conclusions: For patients with head and neck cancer who required replanning mainly due to weight loss, there were no significant differences in plan robustness between step-and-shoot IMRT and VMAT. This information is useful with increased clinical adoption of VMAT.« less

Assessment of the accuracy of AortaScan for detection of abdominal aortic aneurysm (AAA).

PubMed

Abbas, A; Smith, A; Cecelja, M; Waltham, M

2012-02-01

AortaScan AMI 9700 is a portable 3D ultrasound device that automatically measures the maximum diameter of the abdominal aorta without the need for a trained sonographer. It is designed to rapidly diagnose or exclude an AAA and may have particular use in screening programs. Our objective was to determine its accuracy to detect AAA. Subjects from our AAA screening and surveillance programs were examined. The aorta was scanned using the AortaScan and computed tomography (CT). Ninety-one subjects underwent imaging (44 AAA on conventional ultrasound surveillance and 47 controls). The largest measurement obtained by AortaScan was compared against the CT-aortic measurement. The mean aortic diameter was 2.8 cm. The CT scan confirmed the diagnosis of AAA in 43 subjects. There was one false positive measurement on conventional ultrasound. AortaScan missed the diagnosis of AAA in eight subjects. There were thirteen false positive measurements. The sensitivity, specificity, positive and negative predictive values were 81%, 72%, 72% and 81% respectively. A device to detect AAA without the need for a trained operator would have potential in a community-based screening programme. The AortaScan, however, lacks adequate sensitivity and significant technical improvement is necessary before it could be considered a replacement for trained screening personnel. Copyright © 2011 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Estimation of patient radiation dose from whole body 18F- FDG PET/CT examination in cancer imaging: a preliminary study

NASA Astrophysics Data System (ADS)

Mahmud, M. H.; Nordin, A. J.; Saad, F. F. Ahmad; Fattah Azman, A. Z.

2014-11-01

This study aims to estimate the radiation effective dose resulting from whole body fluorine-18 flourodeoxyglucose Positron Emission Tomography (18F-FDG PET) scanning as compared to conservative Computed Tomography (CT) techniques in evaluating oncology patients. We reviewed 19 oncology patients who underwent 18F-FDG PET/CT at our centre for cancer staging. Internal and external doses were estimated using radioactivity of injected FDG and volume CT Dose Index (CTDIvol), respectively with employment of the published and modified dose coefficients. The median differences of dose among the conservative CT and PET protocols were determined using Kruskal Wallis test with p < 0.05 considered as significant. The median (interquartile range, IQR) effective doses of non-contrasted CT, contrasted CT and PET scanning protocols were 7.50 (9.35) mSv, 9.76 (3.67) mSv and 6.30 (1.20) mSv, respectively, resulting in the total dose of 21.46 (8.58) mSv. Statistically significant difference was observed in the median effective dose between the three protocols (p < 0.01). The effective doses of whole body 18F-FDG PET technique may be effective the lowest amongst the conventional CT imaging techniques.

Development and validation of automated 2D-3D bronchial airway matching to track changes in regional bronchial morphology using serial low-dose chest CT scans in children with chronic lung disease.

PubMed

Raman, Pavithra; Raman, Raghav; Newman, Beverley; Venkatraman, Raman; Raman, Bhargav; Robinson, Terry E

2010-12-01

To address potential concern for cumulative radiation exposure with serial spiral chest computed tomography (CT) scans in children with chronic lung disease, we developed an approach to match bronchial airways on low-dose spiral and low-dose high-resolution CT (HRCT) chest images to allow serial comparisons. An automated algorithm matches the position and orientation of bronchial airways obtained from HRCT slices with those in the spiral CT scan. To validate this algorithm, we compared manual matching vs automatic matching of bronchial airways in three pediatric patients. The mean absolute percentage difference between the manually matched spiral CT airway and the index HRCT airways were 9.4 ± 8.5% for the internal diameter measurements, 6.0 ± 4.1% for the outer diameter measurements, and 10.1 ± 9.3% for the wall thickness measurements. The mean absolute percentage difference between the automatically matched spiral CT airway measurements and index HRCT airway measurements were 9.2 ± 8.6% for the inner diameter, 5.8 ± 4.5% for the outer diameter, and 9.9 ± 9.5% for the wall thickness. The overall difference between manual and automated methods was 2.1 ± 1.2%, which was significantly less than the interuser variability of 5.1 ± 4.6% (p<0.05). Tests of equivalence had p<0.05, demonstrating no significant difference between the two methods. The time required for matching was significantly reduced in the automated method (p<0.01) and was as accurate as manual matching, allowing efficient comparison of airways obtained on low-dose spiral CT imaging with low-dose HRCT scans.

Comparison of CT and MRI in diagnosis of cerebrospinal leak induced by multiple fractures of skull base

PubMed Central

Wang, Xuhui; Xu, Minhui; Liang, Hong; Xu, Lunshan

2011-01-01

Background Multiple basilar skull fracture and cerebrospinal leak are common complications of traumatic brain injury, which required a surgical repair. But due to the complexity of basilar skull fracture after severe trauma, preoperatively an exact radiological location is always difficult. Multi-row spiral CT and MRI are currently widely applied in the clinical diagnosis. The present study was performed to compare the accuracy of cisternography by multi-row spiral CT and MRI in the diagnosis of cerebrospinal leak. Methods A total of 23 patients with multiple basilar skull fracture after traumatic brain injury were included. The radiological and surgical data were retrospectively analyzed. 64-row CT (mm/row) scan and three-dimensional reconstruction were performed in 12 patients, while MR plain scan and cisternography were performed in another 11 patients. The location of cerebrospinal leak was diagnosed by 2 experienced physicians majoring neurological radiology. Surgery was performed in all patients. The cerebrospinal leak location was confirmed and repaired during surgery. The result was considered as accurate when cerebrospinal leak was absent after surgery. Results According to the surgical exploration, the preoperative diagnosis of the active cerebrospinal leak location was accurate in 9 out of 12 patients with CT scan. The location could not be confirmed by CT because of multiple fractures in 2 patients and the missed diagnosis occurred in 1 patient. The preoperative diagnosis was accurate in 10 out of 11 patients with MRI examination. Conclusions MRI cisternography is more advanced than multi-row CT scan in multiple basilar skull fracture. The combination of the two examinations may increase the diagnostic ratio of active cerebrospinal leak. PMID:22933941

SU-F-I-47: Optimizing Protocols for Image Quality and Dose in Abdominal CT of Large Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, L; Yester, M

Purpose: Newer CT scanners are able to use scout views to adjust mA throughout the scan in order to achieve a given noise level. However, given constraints of radiologist preferences for kVp and rotation time, it may not be possible to achieve an acceptable noise level for large patients. A study was initiated to determine for which patients kVp and/or rotation time should be changed in order to achieve acceptable image quality. Methods: Patient scans were reviewed on two new Emergency Department scanners (Philips iCT) to identify patients over a large range of sizes. These iCTs were set with amore » limit of 500 mA to safeguard against a failure that might cause a CT scan to be (incorrectly) obtained at too-high mA. Scout views of these scans were assessed for both AP and LAT patient width and AP and LAT standard deviation in an ROI over the liver. Effective diameter and product of the scout standard deviations over the liver were both studied as possible metrics for identifying patients who would need kVp and/or rotation time changed. The mA used for the liver in the CT was compared to these metrics for those patients whose CT scans showed acceptable image quality. Results: Both effective diameter and product of the scout standard deviations over the liver result in similar predictions for which patients will require the kVp and/or rotation time to be changed to achieve an optimal combination of image quality and dose. Conclusion: Two mechanisms for CT technologists to determine based on scout characteristics what kVp, mA limit, and rotation time to use when DoseRight with our physicians’ preferred kVp and rotation time will not yield adequate image quality are described.« less

Patient-specific radiation dose and cancer risk estimation in CT: Part I. Development and validation of a Monte Carlo program

PubMed Central

Li, Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Toncheva, Greta; Yoshizumi, Terry T.; Frush, Donald P.

2011-01-01

Purpose: Radiation-dose awareness and optimization in CT can greatly benefit from a dose-reporting system that provides dose and risk estimates specific to each patient and each CT examination. As the first step toward patient-specific dose and risk estimation, this article aimed to develop a method for accurately assessing radiation dose from CT examinations. Methods: A Monte Carlo program was developed to model a CT system (LightSpeed VCT, GE Healthcare). The geometry of the system, the energy spectra of the x-ray source, the three-dimensional geometry of the bowtie filters, and the trajectories of source motions during axial and helical scans were explicitly modeled. To validate the accuracy of the program, a cylindrical phantom was built to enable dose measurements at seven different radial distances from its central axis. Simulated radial dose distributions in the cylindrical phantom were validated against ion chamber measurements for single axial scans at all combinations of tube potential and bowtie filter settings. The accuracy of the program was further validated using two anthropomorphic phantoms (a pediatric one-year-old phantom and an adult female phantom). Computer models of the two phantoms were created based on their CT data and were voxelized for input into the Monte Carlo program. Simulated dose at various organ locations was compared against measurements made with thermoluminescent dosimetry chips for both single axial and helical scans. Results: For the cylindrical phantom, simulations differed from measurements by −4.8% to 2.2%. For the two anthropomorphic phantoms, the discrepancies between simulations and measurements ranged between (−8.1%, 8.1%) and (−17.2%, 13.0%) for the single axial scans and the helical scans, respectively. Conclusions: The authors developed an accurate Monte Carlo program for assessing radiation dose from CT examinations. When combined with computer models of actual patients, the program can provide accurate dose estimates for specific patients. PMID:21361208

Correction for human head motion in helical x-ray CT

NASA Astrophysics Data System (ADS)

Kim, J.-H.; Sun, T.; Alcheikh, A. R.; Kuncic, Z.; Nuyts, J.; Fulton, R.

2016-02-01

Correction for rigid object motion in helical CT can be achieved by reconstructing from a modified source-detector orbit, determined by the object motion during the scan. This ensures that all projections are consistent, but it does not guarantee that the projections are complete in the sense of being sufficient for exact reconstruction. We have previously shown with phantom measurements that motion-corrected helical CT scans can suffer from data-insufficiency, in particular for severe motions and at high pitch. To study whether such data-insufficiency artefacts could also affect the motion-corrected CT images of patients undergoing head CT scans, we used an optical motion tracking system to record the head movements of 10 healthy volunteers while they executed each of the 4 different types of motion (‘no’, slight, moderate and severe) for 60 s. From these data we simulated 354 motion-affected CT scans of a voxelized human head phantom and reconstructed them with and without motion correction. For each simulation, motion-corrected (MC) images were compared with the motion-free reference, by visual inspection and with quantitative similarity metrics. Motion correction improved similarity metrics in all simulations. Of the 270 simulations performed with moderate or less motion, only 2 resulted in visible residual artefacts in the MC images. The maximum range of motion in these simulations would encompass that encountered in the vast majority of clinical scans. With severe motion, residual artefacts were observed in about 60% of the simulations. We also evaluated a new method of mapping local data sufficiency based on the degree to which Tuy’s condition is locally satisfied, and observed that areas with high Tuy values corresponded to the locations of residual artefacts in the MC images. We conclude that our method can provide accurate and artefact-free MC images with most types of head motion likely to be encountered in CT imaging, provided that the motion can be accurately determined.

TH-E-17A-07: Improved Cine Four-Dimensional Computed Tomography (4D CT) Acquisition and Processing Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castillo, S; Castillo, R; Castillo, E

2014-06-15

Purpose: Artifacts arising from the 4D CT acquisition and post-processing methods add systematic uncertainty to the treatment planning process. We propose an alternate cine 4D CT acquisition and post-processing method to consistently reduce artifacts, and explore patient parameters indicative of image quality. Methods: In an IRB-approved protocol, 18 patients with primary thoracic malignancies received a standard cine 4D CT acquisition followed by an oversampling 4D CT that doubled the number of images acquired. A second cohort of 10 patients received the clinical 4D CT plus 3 oversampling scans for intra-fraction reproducibility. The clinical acquisitions were processed by the standard phasemore » sorting method. The oversampling acquisitions were processed using Dijkstras algorithm to optimize an artifact metric over available image data. Image quality was evaluated with a one-way mixed ANOVA model using a correlation-based artifact metric calculated from the final 4D CT image sets. Spearman correlations and a linear mixed model tested the association between breathing parameters, patient characteristics, and image quality. Results: The oversampling 4D CT scans reduced artifact presence significantly by 27% and 28%, for the first cohort and second cohort respectively. From cohort 2, the inter-replicate deviation for the oversampling method was within approximately 13% of the cross scan average at the 0.05 significance level. Artifact presence for both clinical and oversampling methods was significantly correlated with breathing period (ρ=0.407, p-value<0.032 clinical, ρ=0.296, p-value<0.041 oversampling). Artifact presence in the oversampling method was significantly correlated with amount of data acquired, (ρ=-0.335, p-value<0.02) indicating decreased artifact presence with increased breathing cycles per scan location. Conclusion: The 4D CT oversampling acquisition with optimized sorting reduced artifact presence significantly and reproducibly compared to the phase-sorted clinical acquisition.« less

Automated Agatston score computation in non-ECG gated CT scans using deep learning

NASA Astrophysics Data System (ADS)

Cano-Espinosa, Carlos; González, Germán.; Washko, George R.; Cazorla, Miguel; San José Estépar, Raúl

2018-03-01

Introduction: The Agatston score is a well-established metric of cardiovascular disease related to clinical outcomes. It is computed from CT scans by a) measuring the volume and intensity of the atherosclerotic plaques and b) aggregating such information in an index. Objective: To generate a convolutional neural network that inputs a non-contrast chest CT scan and outputs the Agatston score associated with it directly, without a prior segmentation of Coronary Artery Calcifications (CAC). Materials and methods: We use a database of 5973 non-contrast non-ECG gated chest CT scans where the Agatston score has been manually computed. The heart of each scan is cropped automatically using an object detector. The database is split in 4973 cases for training and 1000 for testing. We train a 3D deep convolutional neural network to regress the Agatston score directly from the extracted hearts. Results: The proposed method yields a Pearson correlation coefficient of r = 0.93; p <= 0.0001 against manual reference standard in the 1000 test cases. It further stratifies correctly 72.6% of the cases with respect to standard risk groups. This compares to more complex state-of-the-art methods based on prior segmentations of the CACs, which achieve r = 0.94 in ECG-gated pulmonary CT. Conclusions: A convolutional neural network can regress the Agatston score from the image of the heart directly, without a prior segmentation of the CACs. This is a new and simpler paradigm in the Agatston score computation that yields similar results to the state-of-the-art literature.

Does head CT scan pathology predict outcome after mild traumatic brain injury?

PubMed

Lannsjö, M; Backheden, M; Johansson, U; Af Geijerstam, J L; Borg, J

2013-01-01

More evidence is needed to forward our understanding of the key determinants of poor outcome after mild traumatic brain injury (MTBI). A large, prospective, national cohort of patients was studied to analyse the effect of head CT scan pathology on the outcome. One-thousand two-hundred and sixty-two patients with MTBI (Glasgow Coma Scale score 15) at 39 emergency departments completed a study protocol including acute head CT scan examination and follow-up by the Rivermead Post Concussion Symptoms Questionnaire and the Glasgow Outcome Scale Extended (GOSE) at 3 months after MTBI. Binary logistic regression was used for the assessment of prediction ability. In 751 men (60%) and 511 women (40%), with a mean age of 30 years (median 21, range 6-94), we observed relevant or suspect relevant pathologic findings on acute CT scan in 52 patients (4%). Patients aged below 30 years reported better outcome both with respect to symptoms and GOSE as compared to patients in older age groups. Men reported better outcome than women as regards symptoms (OR 0.64, CI 0.49-0.85 for ≥3 symptoms) and global function (OR 0.60, CI 0.39-0.92 for GOSE 1-6). Pathology on acute CT scan examination had no effect on self-reported symptoms or global function at 3 months after MTBI. Female gender and older age predicted a less favourable outcome. The findings support the view that other factors than brain injury deserve attention to minimize long-term complaints after MTBI. © 2012 The Author(s) European Journal of Neurology © 2012 EFNS.

Developing patient-specific dose protocols for a CT scanner and exam using diagnostic reference levels.

PubMed

Strauss, Keith J

2014-10-01

The management of image quality and radiation dose during pediatric CT scanning is dependent on how well one manages the radiographic techniques as a function of the type of exam, type of CT scanner, and patient size. The CT scanner's display of expected CT dose index volume (CTDIvol) after the projection scan provides the operator with a powerful tool prior to the patient scan to identify and manage appropriate CT techniques, provided the department has established appropriate diagnostic reference levels (DRLs). This paper provides a step-by-step process that allows the development of DRLs as a function of type of exam, of actual patient size and of the individual radiation output of each CT scanner in a department. Abdomen, pelvis, thorax and head scans are addressed. Patient sizes from newborns to large adults are discussed. The method addresses every CT scanner regardless of vendor, model or vintage. We cover adjustments to techniques to manage the impact of iterative reconstruction and provide a method to handle all available voltages other than 120 kV. This level of management of CT techniques is necessary to properly monitor radiation dose and image quality during pediatric CT scans.

BODY SIZE-SPECIFIC EFFECTIVE DOSE CONVERSION COEFFICIENTS FOR CT SCANS.

PubMed

Romanyukha, Anna; Folio, Les; Lamart, Stephanie; Simon, Steven L; Lee, Choonsik

2016-12-01

Effective dose from computed tomography (CT) examinations is usually estimated using the scanner-provided dose-length product and using conversion factors, also known as k-factors, which correspond to scan regions and differ by age according to five categories: 0, 1, 5, 10 y and adult. However, patients often deviate from the standard body size on which the conversion factor is based. In this study, a method for deriving body size-specific k-factors is presented, which can be determined from a simple regression curve based on patient diameter at the centre of the scan range. Using the International Commission on Radiological Protection reference paediatric and adult computational phantoms paired with Monte Carlo simulation of CT X-ray beams, the authors derived a regression-based k-factor model for the following CT scan types: head-neck, head, neck, chest, abdomen, pelvis, abdomen-pelvis (AP) and chest-abdomen-pelvis (CAP). The resulting regression functions were applied to a total of 105 paediatric and 279 adult CT scans randomly sampled from patients who underwent chest, AP and CAP scans at the National Institutes of Health Clinical Center. The authors have calculated and compared the effective doses derived from the conventional age-specific k-factors with the values computed using their body size-specific k-factor. They found that by using the age-specific k-factor, paediatric patients tend to have underestimates (up to 3-fold) of effective dose, while underweight and overweight adult patients tend to have underestimates (up to 2.6-fold) and overestimates (up to 4.6-fold) of effective dose, respectively, compared with the effective dose determined from their body size-dependent factors. The authors present these size-specific k-factors as an alternative to the existing age-specific factors. The body size-specific k-factor will assess effective dose more precisely and on a more individual level than the conventional age-specific k-factors and, hence, improve awareness of the true exposure, which is important for the clinical community to understand. Published by Oxford University Press 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Transcranial color-coded duplex sonography for evaluation of midline-shift after chronic-subdural hematoma evacuation (TEMASE): A prospective study.

PubMed

Cattalani, Andrea; Grasso, Vincenzo Maria; Vitali, Matteo; Gallesio, Ivan; Magrassi, Lorenzo; Barbanera, Andrea

2017-11-01

The incidence of chronic Subdural hematoma (cSDH) is increasing and its rate of recurrence varies from 5 to 33%. A postoperative brain midline-shift (MLS) on computed tomography (CT) equal or larger than 5mm is a risk factor for recurrence. Transcranial color-coded duplex sonography (TCCDS) is a noninvasive bedside reproducible technique useful to detect MLS. The aim of our study was to compare in patients affected by cSDH, the values of MLS obtained pre- and post-operatively by TCCDS and brain CT. 32 patients affected by cSDH entered the study between July 2016 and January 2017. MLS values obtained by TCCDS and brain CT were compared using Bland-Altman plot and linear regression analysis. Using the same techniques we also explored if the agreement between the two imaging modes was comparable in pre- and post-operative data pairs. 64 data pairs of MLS values obtained by TCCDS and CT were analysed. Bland-Altman diagrams did not show any systematic bias of the data and linear regression indicated a significant correlation between the two measures both before and after hematoma evacuation. In patients affected by cSDH, MLS values obtained before and after surgery by TCCDS are comparable to those obtained by CT; TCCDS might be considered an alternative to CT scan in the management of patients after cSDH evacuation. We suggest that close clinical bedside examination and TCCDS might be appropriate for the post-operative management of cSDH, reserving CT scan only to patients with overt clinical deterioration and/or increasing MLS. Copyright © 2017 Elsevier B.V. All rights reserved.

Accuracy of Canadian CT head rule in predicting positive findings on CT of the head of patients after mild head injury in a large trauma centre in Saudi Arabia

PubMed Central

Arab, Ala Faisal; Ahmed, Anwar E; Hussein, Mohamed Ahmed; Khankan, Azzam A; Alokaili, Riyadh Nasser

2015-01-01

Background Investigation of unjustified computed tomography (CT) scan in patients with minor head injury is lacking in Saudi Arabia. The purpose of the study was to evaluate the compliance and effectiveness of the Canadian computed tomography head rule (CCHR) in our emergency department (ED) and trauma centre and also to reduce the number of unjustified CT studies of the head in the centre. Methods A retrospective study of 368 ED patients with minor head injury was conducted. Patients who underwent CT scan between July 2010 and June 2011were selected from the ED head trauma registry by systematic randomisation. The CCHR was retrospectively applied on the patients’ charts to calculate the prevalence of unjustified head CT scans. A separate survey was conducted to evaluate three emergency physicians’ level of awareness about the CCHR and their ability to determine the necessity of CT scans with various clinical scenarios of head injury. Results The prevalence of unjustified CT scans as per the CCHR was 61.8% (95% confidence interval (CI) 56.5–66.9%). Approximately 5% of the sample had positive CT findings with 95% CI 2.9–7.6%. The CCHR correctly identified 12 cases with positive CT findings with 66.67% sensitivity. Only 24 (6.7%) had Glasgow coma scale scores less than 15 (13/14). The Glasgow coma scale correctly identified only two cases with positive CT findings with 11.11% sensitivity. The percentage of skull fracture (0.9% vs 5%, P = 0.030) was significantly lower in patients with unjustified CT scans than in patients with clinically justified CT scans. There was fair to substantial agreement between the ED physicians and the CCHR (κ = 35–61%). Two ED physicians identified all cases of justified CT scan with 100% sensitivity (95% CI 71.51–100%). Conclusion The level of education regarding the CCHR was found to be optimal among emergency physicians using a case-based scenario survey. The CCHR was found to have a poor compliance potential in the busy ED of our trauma centre and the prevalence of unjustified cranial CT scans remained high. PMID:26471399

Anastomotic leaks: what is the best diagnostic imaging study?

PubMed

Nicksa, G A; Dring, R V; Johnson, K H; Sardella, W V; Vignati, P V; Cohen, J L

2007-02-01

Postoperative anastomotic leaks are one of the most devastating consequences of colorectal surgery. Diagnostic imaging for upper gastrointestinal anastomotic leaks has been evaluated and reported on extensively. No study has compared the utility and effectiveness of CT scans and water-soluble enemas for the identification of postoperative lower gastrointestinal anastomotic leaks. The present study was designed to evaluate and compare these two common radiographic imaging modalities in detecting lower gastrointestinal anastomotic leaks. A retrospective chart review was performed that identified 36 patients during a seven-year period who underwent reoperative surgery for a lower gastrointestinal anastomotic leak. Patient's imaging studies were classified as positive if extravasation of contrast material was demonstrated. When negative, a study was retrospectively reviewed in an attempt to identify findings suggestive of an anastomotic leak. There were 36 patients identified with a postoperative lower gastrointestinal leak requiring surgical intervention. There were 28 of 36 patients (78 percent) re-explored on the basis of a radiologic study demonstrating an anastomotic leak. A total of 27 CT scans were performed, of which 4 (14.8 percent) were considered positive for an anastomotic leak. On review of the remaining negative CT scans, nine (33.3 percent) were considered descriptive positive with a large amount of fluid or air in the peritoneal cavity but without obvious extravasation of contrast. Eighteen patients were evaluated with a water-soluble enema and 15 (83.3 percent) demonstrated extravasation of contrast material. In the 26 patients with a distal anastomotic leak, 17 water-soluble enemas were performed, with 15 (88 percent) demonstrating a leak. In contrast, only 2 of 17 (12 percent) CT scans were positive in this group of patients (P < 0.001). There were ten patients who initially had a CT scan followed by a water-soluble enema. Of these patients, eight of nine (88 percent) initially had a negative CT scan but were considered to be clinically suspicious of having an anastomotic leak and subsequently had a leak demonstrated on a water-soluble enema. Early intervention in patients who develop an anastomotic leak can be shown to improve the ultimate outcome, especially with respect to mortality. It is usually necessary to obtain objective tests of anastomotic integrity because of the nonspecificity of clinical signs. Our study supported the superiority of water-soluble enema to CT imaging in patients in whom both modalities were used. This difference was most pronounced for distal anastomotic leaks, whereas no radiologic imaging study proved effective in evaluating proximal anastomoses.

SU-E-J-251: Incorporation of Pre-Therapy 18F-FDG Uptake with CT Texture Features in a Predictive Model for Radiation Pneumonitis Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anthony, G; Cunliffe, A; Armato, S

2015-06-15

Purpose: To determine whether the addition of standardized uptake value (SUV) statistical variables to CT lung texture features can improve a predictive model of radiation pneumonitis (RP) development in patients undergoing radiation therapy. Methods: Anonymized data from 96 esophageal cancer patients (18 RP-positive cases of Grade ≥ 2) were retrospectively collected including pre-therapy PET/CT scans, pre-/posttherapy diagnostic CT scans and RP status. Twenty texture features (firstorder, fractal, Laws’ filter and gray-level co-occurrence matrix) were calculated from diagnostic CT scans and compared in anatomically matched regions of the lung. The mean, maximum, standard deviation, and 50th–95th percentiles of the SUV valuesmore » for all lung voxels in the corresponding PET scans were acquired. For each texture feature, a logistic regression-based classifier consisting of (1) the average change in that texture feature value between the pre- and post-therapy CT scans and (2) the pre-therapy SUV standard deviation (SUV{sub SD}) was created. The RP-classification performance of each logistic regression model was compared to the performance of its texture feature alone by computing areas under the receiver operating characteristic curves (AUCs). T-tests were performed to determine whether the mean AUC across texture features changed significantly when SUV{sub SD} was added to the classifier. Results: The AUC for single-texturefeature classifiers ranged from 0.58–0.81 in high-dose (≥ 30 Gy) regions of the lungs and from 0.53–0.71 in low-dose (< 10 Gy) regions. Adding SUVSD in a logistic regression model using a 50/50 data partition for training and testing significantly increased the mean AUC by 0.08, 0.06 and 0.04 in the low-, medium- and high-dose regions, respectively. Conclusion: Addition of SUVSD from a pre-therapy PET scan to a single CT-based texture feature improves RP-classification performance on average. These findings demonstrate the potential for more accurate prediction of RP using information from multiple imaging modalities. Supported, in part, by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under grant number T32 EB002103; SGA receives royalties and licensing fees through the University of Chicago for computer-aided diagnosis technology. HA receives royalties through the University of Chicago for computer-aided diagnosis technology.« less

3D documentation and visualization of external injury findings by integration of simple photography in CT/MRI data sets (IprojeCT).

PubMed

Campana, Lorenzo; Breitbeck, Robert; Bauer-Kreuz, Regula; Buck, Ursula

2016-05-01

This study evaluated the feasibility of documenting patterned injury using three dimensions and true colour photography without complex 3D surface documentation methods. This method is based on a generated 3D surface model using radiologic slice images (CT) while the colour information is derived from photographs taken with commercially available cameras. The external patterned injuries were documented in 16 cases using digital photography as well as highly precise photogrammetry-supported 3D structured light scanning. The internal findings of these deceased were recorded using CT and MRI. For registration of the internal with the external data, two different types of radiographic markers were used and compared. The 3D surface model generated from CT slice images was linked with the photographs, and thereby digital true-colour 3D models of the patterned injuries could be created (Image projection onto CT/IprojeCT). In addition, these external models were merged with the models of the somatic interior. We demonstrated that 3D documentation and visualization of external injury findings by integration of digital photography in CT/MRI data sets is suitable for the 3D documentation of individual patterned injuries to a body. Nevertheless, this documentation method is not a substitution for photogrammetry and surface scanning, especially when the entire bodily surface is to be recorded in three dimensions including all external findings, and when precise data is required for comparing highly detailed injury features with the injury-inflicting tool.

Image quality and radiation dose of brain computed tomography in children: effects of decreasing tube voltage from 120 kVp to 80 kVp.

PubMed

Park, Ji Eun; Choi, Young Hun; Cheon, Jung-Eun; Kim, Woo Sun; Kim, In-One; Cho, Hyun Suk; Ryu, Young Jin; Kim, Yu Jin

2017-05-01

Computed tomography (CT) has generated public concern associated with radiation exposure, especially for children. Lowering the tube voltage is one strategy to reduce radiation dose. To assess the image quality and radiation dose of non-enhanced brain CT scans acquired at 80 kilo-voltage peak (kVp) compared to those at 120 kVp in children. Thirty children who had undergone both 80- and 120-kVp non-enhanced brain CT were enrolled. For quantitative analysis, the mean attenuation of white and gray matter, attenuation difference, noise, signal-to-noise ratio, contrast-to-noise ratio and posterior fossa artifact index were measured. For qualitative analysis, noise, gray-white matter differentiation, artifact and overall image quality were scored. Radiation doses were evaluated by CT dose index, dose-length product and effective dose. The mean attenuations of gray and white matter and contrast-to-noise ratio were significantly increased at 80 kVp, while parameters related to image noise, i.e. noise, signal-to-noise ratio and posterior fossa artifact index were higher at 80 kVp than at 120 kVp. In qualitative analysis, 80-kVp images showed improved gray-white differentiation but more artifacts compared to 120-kVp images. Subjective image noise and overall image quality scores were similar between the two scans. Radiation dose parameters were significantly lower at 80 kVp than at 120 kVp. In pediatric non-enhanced brain CT scans, a decrease in tube voltage from 120 kVp to 80 kVp resulted in improved gray-white matter contrast, comparable image quality and decreased radiation dose.

Reducing Radiation Dose in Adult Head CT using Iterative Reconstruction - A Clinical Study in 177 Patients.

PubMed

Kaul, D; Kahn, J; Huizing, L; Wiener, E; Grupp, U; Böning, G; Ghadjar, P; Renz, D M; Streitparth, F

2016-02-01

To assess how ASIR (adaptive statistical iterative reconstruction) contributes to dose reduction and affects image quality of non-contrast cranial computed tomography (cCT). Non-contrast emergency CT scans of the head acquired in 177 patients were evaluated. The scans were acquired and processed using four different protocols: Group A (control): 120 kV, FBP (filtered back projection) n = 71; group B1: 120 kV, scan and reconstruction performed with 20 % ASIR (blending of 20 % ASIR and 80 % FBP), n = 86; group B2: raw data from group B1 reconstructed using a blending of 40 % ASIR and 60 % FBP, n = 74; group C1: 120 kV, scan and reconstruction performed with 30 % ASIR, n = 20; group C2: raw data from group C1 reconstructed using a blending of 50 % ASIR and 50 % FBP, n = 20. The effective dose was calculated. Image quality was assessed quantitatively and qualitatively. Compared to group A, groups B1/2 and C1/2 showed a significantly reduced effective dose of 40.4 % and 73.3 % (p < 0.0001), respectively. Group B1 and group C1/2 also showed significantly reduced quantitative and qualitative image quality parameters. In group B2, quantitative measures were comparable to group A, and qualitative scores were lower compared to group A but higher compared to group B1. Diagnostic confidence grading showed groups B1/2 to be adequate for everyday clinical practice. Group C2 was considered acceptable for follow-up imaging of severe acute events such as bleeding or subacute stroke. Use of ASIR makes it possible to reduce radiation significantly while maintaining adequate image quality in non-contrast head CT, which may be particularly useful for younger patients in an emergency setting and in follow-up. ASIR may reduce radiation significantly while maintaining adequate image quality. cCT protocol with 20 % ASIR and 40 %ASIR/60 %FBP blending is adequate for everyday clinical use. cCT protocol with 30 % ASIR and 50 %ASIR/50 %FBP blending is adequate for follow-up imaging © Georg Thieme Verlag KG Stuttgart · New York.

Evaluation of optimal parameters for using low-dose computed tomography to diagnose urolithiasis

NASA Astrophysics Data System (ADS)

Chen, Hui-Hsien; Yu, Cheng-Ching; Hsu, Fang-Yuh

2017-11-01

Urolithiasis is a common disease; patients suspected of suffering from urolithiasis will be examined by abdomen x-ray, Sono, Intraudio Videonous Urography (IVU) and Computed Tomography (CT). The detection rates for calculus in above examinations are respectively: 50-70% (x-ray), 50-60% (Sono), 70-90% (IVU) and 97% (CT). In addition, the effective doses are respectively: 0.63 mSv (x-ray), no radiation dose (Sono), 2.6 mSv (IVU) and 8-16 mSv (CT). Although CT has the highest detection rate for calculus, it also has the highest radiation dose. This research sought to lower the radiation dose by using CT scans with different dose conditions of standard dose (SD), 50% SD, 25% SD, and 15% SD to diagnose patients who suffer from urolithiasis and thus explore the feasibility of examining urolithiasis via CT with lower dose conditions. This research simulated the examination of patients with RANDO phantom, collocating PMMA slice phantom and pig's kidney. Fake calculuses made of five different materials of different sizes were put into the phantom and scanned individually. The results of the scanned images were given to two physicians who had many years of diagnostic experience to interpret the urolithiasis images. This study explored the different image qualities of CT with different dose conditions. In addition, this research used thermoluminescent dosimeters (TLD) to measure the radiation doses and compared the results with the dose values shown on the screen of the CT scanner to estimate the dose conversion factor (k). The research results showed that a low-dose CT was able to provide good image quality and thus have a lower radiation dose. Therefore, a low-dose CT is suggested the main examination method to diagnose patients with urolithiasis.

Interobserver reliability of computed tomographic contouring of canine tonsils in radiation therapy treatment planning.

PubMed

Murakami, Keiko; Rancilio, Nicholas J; Plantenga, Jeannie Poulson; Moore, George E; Heng, Hock Gan; Lim, Chee Kin

2018-05-01

In radiation therapy (RT) treatment planning for canine head and neck cancer, the tonsils may be included as part of the treated volume. Delineation of tonsils on computed tomography (CT) scans is difficult. Error or uncertainty in the volume and location of contoured structures may result in treatment failure. The purpose of this prospective, observer agreement study was to assess the interobserver agreement of tonsillar contouring by two groups of trained observers. Thirty dogs undergoing pre- and post-contrast CT studies of the head were included. After the pre- and postcontrast CT scans, the tonsils were identified via direct visualization, barium paste was applied bilaterally to the visible tonsils, and a third CT scan was acquired. Data from each of the three CT scans were registered in an RT treatment planning system. Two groups of observers (one veterinary radiologist and one veterinary radiation oncologist in each group) contoured bilateral tonsils by consensus, obtaining three sets of contours. Tonsil volume and location data were obtained from both groups. The contour volumes and locations were compared between groups using mixed (fixed and random effect) linear models. There was no significant difference between each group's contours in terms of three-dimensional coordinates. However there was a significant difference between each group's contours in terms of the tonsillar volume (P < 0.0001). Pre- and postcontrast CT can be used to identify the location of canine tonsils with reasonable agreement between trained observers. Discrepancy in tonsillar volume between groups of trained observers may affect RT treatment outcome. © 2017 American College of Veterinary Radiology.

Spectral performance of a whole-body research photon counting detector CT: quantitative accuracy in derived image sets

NASA Astrophysics Data System (ADS)

Leng, Shuai; Zhou, Wei; Yu, Zhicong; Halaweish, Ahmed; Krauss, Bernhard; Schmidt, Bernhard; Yu, Lifeng; Kappler, Steffen; McCollough, Cynthia

2017-09-01

Photon-counting computed tomography (PCCT) uses a photon counting detector to count individual photons and allocate them to specific energy bins by comparing photon energy to preset thresholds. This enables simultaneous multi-energy CT with a single source and detector. Phantom studies were performed to assess the spectral performance of a research PCCT scanner by assessing the accuracy of derived images sets. Specifically, we assessed the accuracy of iodine quantification in iodine map images and of CT number accuracy in virtual monoenergetic images (VMI). Vials containing iodine with five known concentrations were scanned on the PCCT scanner after being placed in phantoms representing the attenuation of different size patients. For comparison, the same vials and phantoms were also scanned on 2nd and 3rd generation dual-source, dual-energy scanners. After material decomposition, iodine maps were generated, from which iodine concentration was measured for each vial and phantom size and compared with the known concentration. Additionally, VMIs were generated and CT number accuracy was compared to the reference standard, which was calculated based on known iodine concentration and attenuation coefficients at each keV obtained from the U.S. National Institute of Standards and Technology (NIST). Results showed accurate iodine quantification (root mean square error of 0.5 mgI/cc) and accurate CT number of VMIs (percentage error of 8.9%) using the PCCT scanner. The overall performance of the PCCT scanner, in terms of iodine quantification and VMI CT number accuracy, was comparable to that of EID-based dual-source, dual-energy scanners.

Study of CT image texture using deep learning techniques

NASA Astrophysics Data System (ADS)

Dutta, Sandeep; Fan, Jiahua; Chevalier, David

2018-03-01

For CT imaging, reduction of radiation dose while improving or maintaining image quality (IQ) is currently a very active research and development topic. Iterative Reconstruction (IR) approaches have been suggested to be able to offer better IQ to dose ratio compared to the conventional Filtered Back Projection (FBP) reconstruction. However, it has been widely reported that often CT image texture from IR is different compared to that from FBP. Researchers have proposed different figure of metrics to quantitate the texture from different reconstruction methods. But there is still a lack of practical and robust method in the field for texture description. This work applied deep learning method for CT image texture study. Multiple dose scans of a 20cm diameter cylindrical water phantom was performed on Revolution CT scanner (GE Healthcare, Waukesha) and the images were reconstructed with FBP and four different IR reconstruction settings. The training images generated were randomly allotted (80:20) to a training and validation set. An independent test set of 256-512 images/class were collected with the same scan and reconstruction settings. Multiple deep learning (DL) networks with Convolution, RELU activation, max-pooling, fully-connected, global average pooling and softmax activation layers were investigated. Impact of different image patch size for training was investigated. Original pixel data as well as normalized image data were evaluated. DL models were reliably able to classify CT image texture with accuracy up to 99%. Results show that the deep learning techniques suggest that CT IR techniques may help lower the radiation dose compared to FBP.

Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

PubMed

Lell, M M; May, M S; Brand, M; Eller, A; Buder, T; Hofmann, E; Uder, M; Wuest, W

2015-07-01

CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT. © 2015 by American Journal of Neuroradiology.

A computed tomography-based spatial normalization for the analysis of [18F] fluorodeoxyglucose positron emission tomography of the brain.

PubMed

Cho, Hanna; Kim, Jin Su; Choi, Jae Yong; Ryu, Young Hoon; Lyoo, Chul Hyoung

2014-01-01

We developed a new computed tomography (CT)-based spatial normalization method and CT template to demonstrate its usefulness in spatial normalization of positron emission tomography (PET) images with [(18)F] fluorodeoxyglucose (FDG) PET studies in healthy controls. Seventy healthy controls underwent brain CT scan (120 KeV, 180 mAs, and 3 mm of thickness) and [(18)F] FDG PET scans using a PET/CT scanner. T1-weighted magnetic resonance (MR) images were acquired for all subjects. By averaging skull-stripped and spatially-normalized MR and CT images, we created skull-stripped MR and CT templates for spatial normalization. The skull-stripped MR and CT images were spatially normalized to each structural template. PET images were spatially normalized by applying spatial transformation parameters to normalize skull-stripped MR and CT images. A conventional perfusion PET template was used for PET-based spatial normalization. Regional standardized uptake values (SUV) measured by overlaying the template volume of interest (VOI) were compared to those measured with FreeSurfer-generated VOI (FSVOI). All three spatial normalization methods underestimated regional SUV values by 0.3-20% compared to those measured with FSVOI. The CT-based method showed slightly greater underestimation bias. Regional SUV values derived from all three spatial normalization methods were correlated significantly (p < 0.0001) with those measured with FSVOI. CT-based spatial normalization may be an alternative method for structure-based spatial normalization of [(18)F] FDG PET when MR imaging is unavailable. Therefore, it is useful for PET/CT studies with various radiotracers whose uptake is expected to be limited to specific brain regions or highly variable within study population.

A comparative study of the target volume definition in radiotherapy with «Slow CT Scan» vs. 4D PET/CT Scan in early stages non-small cell lung cancer.

PubMed

Molla, M; Anducas, N; Simó, M; Seoane, A; Ramos, M; Cuberas-Borros, G; Beltran, M; Castell, J; Giralt, J

To evaluate the use of 4D PET/CT to quantify tumor respiratory motion compared to the «Slow»-CT (CTs) in the radiotherapy planning process. A total of 25 patients with inoperable early stage non small cell lung cancer (NSCLC) were included in the study. Each patient was imaged with a CTs (4s/slice) and 4D PET/CT. The adequacy of each technique for respiratory motion capture was evaluated using the volume definition for each of the following: Internal target volume (ITV) 4D and ITVslow in relation with the volume defined by the encompassing volume of 4D PET/CT and CTs (ITVtotal). The maximum distance between the edges of the volume defined by each technique to that of the total volume was measured in orthogonal beam's eye view. The ITV4D showed less differences in relation with the ITVtotal in both the cranio-caudal and the antero-posterior axis compared to the ITVslow. The maximum differences were 0.36mm in 4D PET/CTand 0.57mm in CTs in the antero-posterior axis. 4D PET/CT resulted in the definition of more accurate (ITV4D/ITVtotal 0.78 vs. ITVs/ITVtotal 0.63), and larger ITVs (19.9 cc vs. 16.3 cc) than those obtained with CTs. Planning with 4D PET/CT in comparison with CTs, allows incorporating tumor respiratory motion and improving planning radiotherapy of patients in early stages of lung cancer. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Automatic estimation of detector radial position for contoured SPECT acquisition using CT images on a SPECT/CT system.

PubMed

Liu, Ruijie Rachel; Erwin, William D

2006-08-01

An algorithm was developed to estimate noncircular orbit (NCO) single-photon emission computed tomography (SPECT) detector radius on a SPECT/CT imaging system using the CT images, for incorporation into collimator resolution modeling for iterative SPECT reconstruction. Simulated male abdominal (arms up), male head and neck (arms down) and female chest (arms down) anthropomorphic phantom, and ten patient, medium-energy SPECT/CT scans were acquired on a hybrid imaging system. The algorithm simulated inward SPECT detector radial motion and object contour detection at each projection angle, employing the calculated average CT image and a fixed Hounsfield unit (HU) threshold. Calculated radii were compared to the observed true radii, and optimal CT threshold values, corresponding to patient bed and clothing surfaces, were found to be between -970 and -950 HU. The algorithm was constrained by the 45 cm CT field-of-view (FOV), which limited the detected radii to < or = 22.5 cm and led to occasional radius underestimation in the case of object truncation by CT. Two methods incorporating the algorithm were implemented: physical model (PM) and best fit (BF). The PM method computed an offset that produced maximum overlap of calculated and true radii for the phantom scans, and applied that offset as a calculated-to-true radius transformation. For the BF method, the calculated-to-true radius transformation was based upon a linear regression between calculated and true radii. For the PM method, a fixed offset of +2.75 cm provided maximum calculated-to-true radius overlap for the phantom study, which accounted for the camera system's object contour detect sensor surface-to-detector face distance. For the BF method, a linear regression of true versus calculated radius from a reference patient scan was used as a calculated-to-true radius transform. Both methods were applied to ten patient scans. For -970 and -950 HU thresholds, the combined overall average root-mean-square (rms) error in radial position for eight patient scans without truncation were 3.37 cm (12.9%) for PM and 1.99 cm (8.6%) for BF, indicating BF is superior to PM in the absence of truncation. For two patient scans with truncation, the rms error was 3.24 cm (12.2%) for PM and 4.10 cm (18.2%) for BF. The slightly better performance of PM in the case of truncation is anomalous, due to FOV edge truncation artifacts in the CT reconstruction, and thus is suspect. The calculated NCO contour for a patient SPECT/CT scan was used with an iterative reconstruction algorithm that incorporated compensation for system resolution. The resulting image was qualitatively superior to the image obtained by reconstructing the data using the fixed radius stored by the scanner. The result was also superior to the image reconstructed using the iterative algorithm provided with the system, which does not incorporate resolution modeling. These results suggest that, under conditions of no or only mild lateral truncation of the CT scan, the algorithm is capable of providing radius estimates suitable for iterative SPECT reconstruction collimator geometric resolution modeling.

In vitro evaluation of the imaging accuracy of C-arm conebeam CT in cerebral perfusion imaging

PubMed Central

Ganguly, A.; Fieselmann, A.; Boese, J.; Rohkohl, C.; Hornegger, J.; Fahrig, R.

2012-01-01

Purpose: The authors have developed a method to enable cerebral perfusion CT imaging using C-arm based conebeam CT (CBCT). This allows intraprocedural monitoring of brain perfusion during treatment of stroke. Briefly, the technique consists of acquiring multiple scans (each scan comprised of six sweeps) acquired at different time delays with respect to the start of the x-ray contrast agent injection. The projections are then reconstructed into angular blocks and interpolated at desired time points. The authors have previously demonstrated its feasibility in vivo using an animal model. In this paper, the authors describe an in vitro technique to evaluate the accuracy of their method for measuring the relevant temporal signals. Methods: The authors’ evaluation method is based on the concept that any temporal signal can be represented by a Fourier series of weighted sinusoids. A sinusoidal phantom was developed by varying the concentration of iodine as successive steps of a sine wave. Each step corresponding to a different dilution of iodine contrast solution contained in partitions along a cylinder. By translating the phantom along the axis at different velocities, sinusoidal signals at different frequencies were generated. Using their image acquisition and reconstruction algorithm, these sinusoidal signals were imaged with a C-arm system and the 3D volumes were reconstructed. The average value in a slice was plotted as a function of time. The phantom was also imaged using a clinical CT system with 0.5 s rotation. C-arm CBCT results using 6, 3, 2, and 1 scan sequences were compared to those obtained using CT. Data were compared for linear velocities of the phantom ranging from 0.6 to 1 cm/s. This covers the temporal frequencies up to 0.16 Hz corresponding to a frequency range within which 99% of the spectral energy for all temporal signals in cerebral perfusion imaging is contained. Results: The errors in measurement of temporal frequencies are mostly below 2% for all multiscan sequences. For single scan sequences, the errors increase sharply beyond 0.10 Hz. The amplitude errors increase with frequency and with decrease in the number of scans used. Conclusions: Our multiscan perfusion CT approach allows low errors in signal frequency measurement. Increasing the number of scans reduces the amplitude errors. A two-scan sequence appears to offer the best compromise between accuracy and the associated total x-ray and iodine dose. PMID:23127059

Myoanatomy of the velvet worm leg revealed by laboratory-based nanofocus X-ray source tomography.

PubMed

Müller, Mark; de Sena Oliveira, Ivo; Allner, Sebastian; Ferstl, Simone; Bidola, Pidassa; Mechlem, Korbinian; Fehringer, Andreas; Hehn, Lorenz; Dierolf, Martin; Achterhold, Klaus; Gleich, Bernhard; Hammel, Jörg U; Jahn, Henry; Mayer, Georg; Pfeiffer, Franz

2017-11-21

X-ray computed tomography (CT) is a powerful noninvasive technique for investigating the inner structure of objects and organisms. However, the resolution of laboratory CT systems is typically limited to the micrometer range. In this paper, we present a table-top nanoCT system in conjunction with standard processing tools that is able to routinely reach resolutions down to 100 nm without using X-ray optics. We demonstrate its potential for biological investigations by imaging a walking appendage of Euperipatoides rowelli , a representative of Onychophora-an invertebrate group pivotal for understanding animal evolution. Comparative analyses proved that the nanoCT can depict the external morphology of the limb with an image quality similar to scanning electron microscopy, while simultaneously visualizing internal muscular structures at higher resolutions than confocal laser scanning microscopy. The obtained nanoCT data revealed hitherto unknown aspects of the onychophoran limb musculature, enabling the 3D reconstruction of individual muscle fibers, which was previously impossible using any laboratory-based imaging technique.

A patch-based pseudo-CT approach for MRI-only radiotherapy in the pelvis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreasen, Daniel, E-mail: dana@dtu.dk

Purpose: In radiotherapy based only on magnetic resonance imaging (MRI), knowledge about tissue electron densities must be derived from the MRI. This can be achieved by converting the MRI scan to the so-called pseudo-computed tomography (pCT). An obstacle is that the voxel intensities in conventional MRI scans are not uniquely related to electron density. The authors previously demonstrated that a patch-based method could produce accurate pCTs of the brain using conventional T{sub 1}-weighted MRI scans. The method was driven mainly by local patch similarities and relied on simple affine registrations between an atlas database of the co-registered MRI/CT scan pairsmore » and the MRI scan to be converted. In this study, the authors investigate the applicability of the patch-based approach in the pelvis. This region is challenging for a method based on local similarities due to the greater inter-patient variation. The authors benchmark the method against a baseline pCT strategy where all voxels inside the body contour are assigned a water-equivalent bulk density. Furthermore, the authors implement a parallelized approximate patch search strategy to speed up the pCT generation time to a more clinically relevant level. Methods: The data consisted of CT and T{sub 1}-weighted MRI scans of 10 prostate patients. pCTs were generated using an approximate patch search algorithm in a leave-one-out fashion and compared with the CT using frequently described metrics such as the voxel-wise mean absolute error (MAE{sub vox}) and the deviation in water-equivalent path lengths. Furthermore, the dosimetric accuracy was tested for a volumetric modulated arc therapy plan using dose–volume histogram (DVH) point deviations and γ-index analysis. Results: The patch-based approach had an average MAE{sub vox} of 54 HU; median deviations of less than 0.4% in relevant DVH points and a γ-index pass rate of 0.97 using a 1%/1 mm criterion. The patch-based approach showed a significantly better performance than the baseline water pCT in almost all metrics. The approximate patch search strategy was 70x faster than a brute-force search, with an average prediction time of 20.8 min. Conclusions: The authors showed that a patch-based method based on affine registrations and T{sub 1}-weighted MRI could generate accurate pCTs of the pelvis. The main source of differences between pCT and CT was positional changes of air pockets and body outline.« less

The dosimetric impact of including the patient table in CT dose estimates

NASA Astrophysics Data System (ADS)

Nowik, Patrik; Bujila, Robert; Kull, Love; Andersson, Jonas; Poludniowski, Gavin

2017-12-01

The purpose of this study was to evaluate the dosimetric impact of including the patient table in Monte Carlo CT dose estimates for both spiral scans and scan projection radiographs (SPR). CT scan acquisitions were simulated for a Siemens SOMATOM Force scanner (Siemens Healthineers, Forchheim, Germany) with and without a patient table present. An adult male, an adult female and a pediatric female voxelized phantom were simulated. The simulated scans included tube voltages of 80 and 120 kVp. Spiral scans simulated without a patient table resulted in effective doses that were overestimated by approximately 5% compared to the same simulations performed with the patient table present. Doses in selected individual organs (breast, colon, lung, red bone marrow and stomach) were overestimated by up to 8%. Effective doses from SPR acquired with the x-ray tube stationary at 6 o’clock (posterior-anterior) were overestimated by 14-23% when the patient table was not included, with individual organ dose discrepancies (breast, colon, lung red bone marrow and stomach) all exceeding 13%. The reference entrance skin dose to the back were in this situation overestimated by 6-15%. These results highlight the importance of including the patient table in patient dose estimates for such scan situations.

Interpretation of Brain CT Scans in the Field by Critical Care Physicians in a Mobile Stroke Unit

PubMed Central

Zakariassen, Erik; Lindner, Thomas; Nome, Terje; Bache, Kristi G.; Røislien, Jo; Gleditsch, Jostein; Solyga, Volker; Russell, David; Lund, Christian G.

2017-01-01

ABSTRACT BACKGROUND AND PURPOSE In acute stroke, thromboembolism or spontaneous hemorrhage abruptly reduces blood flow to a part of the brain. To limit necrosis, rapid radiological identification of the pathological mechanism must be conducted to allow the initiation of targeted treatment. The aim of the Norwegian Acute Stroke Prehospital Project is to determine if anesthesiologists, trained in prehospital critical care, may accurately assess cerebral computed tomography (CT) scans in a mobile stroke unit (MSU). METHODS In this pilot study, 13 anesthesiologists assessed unselected acute stroke patients with a cerebral CT scan in an MSU. The scans were simultaneously available by teleradiology at the receiving hospital and the on‐call radiologist. CT scan interpretation was focused on the radiological diagnosis of acute stroke and contraindications for thrombolysis. The aim of this study was to find inter‐rater agreement between the pre‐ and in‐hospital radiological assessments. A neuroradiologist evaluated all CT scans retrospectively. Statistical analysis of inter‐rater agreement was analyzed with Cohen's kappa. RESULTS Fifty‐one cerebral CT scans from the MSU were included. Inter‐rater agreement between prehospital anesthesiologists and the in‐hospital on‐call radiologists was excellent in finding radiological selection for thrombolysis (kappa .87). Prehospital CT scans were conducted in median 10 minutes (7 and 14 minutes) in the MSU, and median 39 minutes (31 and 48 minutes) before arrival at the receiving hospital. CONCLUSION This pilot study shows that anesthesiologists trained in prehospital critical care may effectively assess cerebral CT scans in an MSU, and determine if there are radiological contraindications for thrombolysis. PMID:28766306

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paschoal, Cinthia M. M.; Ferreira, Fernanda Carla L.; Santos, Luiz A. P.

The advance of multislice computed tomography (CT) has become inadequate the currently dosimetric protocol used in CT. Instead of dosimetry based on the measurement of CTDI using a pencil ion chamber of 100 m of length, it was proposed the use of a small ion chamber (IC) and the calculating the dose equilibrium (Deq) at the location of the chamber. The objective of this work was to compare the performance of a short IC and a commercial photodiode to measure the accumulated dose at the center of the scan length L, DL(0), and to obtain the equilibrium dose Deq usingmore » the two detectors. The result for L=100 mm was compared with the result of a pencil chamber. The results indicate that the commercial photodiode is suitable to measure the accumulated dose at the center of the scan length L as compared with the ion chambers. This methodology allows measurements of the accumulated dose for any desired scan length, allowing measuring the equilibrium dose Deq if the phantom is long enough to allow it. (authors)« less

Technical Note: Evaluation of a 160-mm/256-row CT scanner for whole-heart quantitative myocardial perfusion imaging.

PubMed

So, Aaron; Imai, Yasuhiro; Nett, Brian; Jackson, John; Nett, Liz; Hsieh, Jiang; Wisenberg, Gerald; Teefy, Patrick; Yadegari, Andrew; Islam, Ali; Lee, Ting-Yim

2016-08-01

The authors investigated the performance of a recently introduced 160-mm/256-row CT system for low dose quantitative myocardial perfusion (MP) imaging of the whole heart. This platform is equipped with a gantry capable of rotating at 280 ms per full cycle, a second generation of adaptive statistical iterative reconstruction (ASiR-V) to correct for image noise arising from low tube voltage potential/tube current dynamic scanning, and image reconstruction algorithms to tackle beam-hardening, cone-beam, and partial-scan effects. Phantom studies were performed to investigate the effectiveness of image noise and artifact reduction with a GE Healthcare Revolution CT system for three acquisition protocols used in quantitative CT MP imaging: 100, 120, and 140 kVp/25 mAs. The heart chambers of an anthropomorphic chest phantom were filled with iodinated contrast solution at different concentrations (contrast levels) to simulate the circulation of contrast through the heart in quantitative CT MP imaging. To evaluate beam-hardening correction, the phantom was scanned at each contrast level to measure the changes in CT number (in Hounsfield unit or HU) in the water-filled region surrounding the heart chambers with respect to baseline. To evaluate cone-beam artifact correction, differences in mean water HU between the central and peripheral slices were compared. Partial-scan artifact correction was evaluated from the fluctuation of mean water HU in successive partial scans. To evaluate image noise reduction, a small hollow region adjacent to the heart chambers was filled with diluted contrast, and contrast-to-noise ratio in the region before and after noise correction with ASiR-V was compared. The quality of MP maps acquired with the CT system was also evaluated in porcine CT MP studies. Myocardial infarct was induced in a farm pig from a transient occlusion of the distal left anterior descending (LAD) artery with a catheter-based interventional procedure. MP maps were generated from the dynamic contrast-enhanced (DCE) heart images taken at baseline and three weeks after the ischemic insult. Their results showed that the phantom and animal images acquired with the CT platform were minimally affected by image noise and artifacts. For the beam-hardening phantom study, changes in water HU in the wall surrounding the heart chambers greatly reduced from >±30 to ≤ ± 5 HU at all kVp settings except one region at 100 kVp (7 HU). For the cone-beam phantom study, differences in mean water HU from the central slice were less than 5 HU at two peripheral slices with each 4 cm away from the central slice. These findings were reproducible in the pig DCE images at two peripheral slices that were 6 cm away from the central slice. For the partial-scan phantom study, standard deviations of the mean water HU in 10 successive partial scans were less than 5 HU at the central slice. Similar observations were made in the pig DCE images at two peripheral slices with each 6 cm away from the central slice. For the image noise phantom study, CNRs in the ASiR-V images were statistically higher (p < 0.05) than the non-ASiR-V images at all kVp settings. MP maps generated from the porcine DCE images were in excellent quality, with the ischemia in the LAD territory clearly seen in the three orthogonal views. The study demonstrates that this CT system can provide accurate and reproducible CT numbers during cardiac gated acquisitions across a wide axial field of view. This CT number fidelity will enable this imaging tool to assess contrast enhancement, potentially providing valuable added information beyond anatomic evaluation of coronary stenoses. Furthermore, their results collectively suggested that the 100 kVp/25 mAs protocol run on this CT system provides sufficient image accuracy at a low radiation dose (<3 mSv) for whole-heart quantitative CT MP imaging.

18F-Choline PET/CT scan in staging and biochemical recurrence in prostate cancer patients: Changes in classification and radiotherapy planning.

PubMed

Cardona Arboniés, J; Rodríguez Alfonso, B; Mucientes Rasilla, J; Martínez Ballesteros, C; Zapata Paz, I; Prieto Soriano, A; Carballido Rodriguez, J; Mitjavila Casanovas, M

To evaluate the role of the 18 F-Choline PET/CT in prostate cancer management when detecting distant disease in planning radiotherapy and staging and to evaluate the therapy changes guided by PET/TC results. A retrospective evaluation was performed on 18 F-Choline PET/CT scans of patients with prostate cancer. Staging and planning radiotherapy scans were selected in patients with at least 9 months follow up. There was a total of 56 studies, 33 (58.93%) for staging, and 23 (41.07%) for planning radiotherapy. All scans were obtained using a hybrid PET/CT scanner. The PET/CT acquisition protocol consisted of a dual-phase procedure after the administration of an intravenous injection of 296-370MBq of 18 F-Choline. There were 43 out of 56 (76.8%) scans considered as positive, and 13 (23.2%) were negative. The TNM staging was changed in 13 (23.2%) scans. The PET/CT findings ruled out distant disease in 4 out of 13 scans, and unknown distant disease was detected in 9 (69.3%) scans. 18 F-Choline PET/CT is a useful technique for detecting unknown distant disease in prostate cancer when staging and planning radiotherapy. The inclusion of 18 F-choline PET/CT should be considered in prostate cancer management protocols. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Validation of calcaneus trabecular microstructure measurements by HR-pQCT.

PubMed

Metcalf, Louis M; Dall'Ara, Enrico; Paggiosi, Margaret A; Rochester, John R; Vilayphiou, Nicolas; Kemp, Graham J; McCloskey, Eugene V

2018-01-01

Assessment of calcaneus microstructure using high-resolution peripheral quantitative computed tomography (HR-pQCT) might be used to improve fracture risk predictions or to assess responses to pharmacological and physical interventions. To develop a standard clinical protocol for the calcaneus, we validated calcaneus trabecular microstructure measured by HR-pQCT against 'gold-standard' micro-CT measurements. Ten human cadaveric feet were scanned in situ using HR-pQCT (isotropic 82μm voxel size) at 100, 150 and 200ms integration times, and at 100ms integration time following removal of the calcaneus from the foot (ex vivo). Dissected portions of these bones were scanned using micro-computed tomography (micro-CT) at an isotropic 17.4μm voxel size. HR-pQCT images were rigidly registered to those obtained with micro-CT and divided into multiple 5mm sided cubes to evaluate and compare morphometric parameters between the modalities. Standard HR-pQCT measurements (derived bone volume fraction (BV/TV d ); trabecular number, Tb.N; derived trabecular thickness, Tb.Th d ; derived trabecular spacing, Tb.Sp d ) and corresponding micro-CT voxel-based measurements (BV/TV, Tb.N, Tb.Th, Tb.Sp) were compared. A total of 108 regions of interest were analysed across the 10 specimens. At all integration times HR-pQCT BV/TV d was strongly correlated with micro-CT BV/TV (r 2 =0.95-0.98, RMSE=1%), but BV/TV d was systematically lower than that measured by micro-CT (mean bias=5%). In contrast, HR-pQCT systematically overestimated Tb.N at all integration times; of the in situ scans, 200ms yielded the lowest mean bias and the strongest correlation with micro-CT (r 2 =0.61, RMSE=0.15mm -1 ). Regional analysis revealed greater accuracy for Tb.N in the superior regions of the calcaneus at all integration times in situ (mean bias=0.44-0.85mm -1 ; r 2 =0.70-0.88, p<0.001 versus mean bias=0.63-1.46mm -1 ; r 2 ≤0.08, p≥0.21 for inferior regions). Tb.Sp d was underestimated by HR-pQCT compared to micro-CT, but showed similar trends with integration time and the region evaluated as Tb.N. HR-pQCT Tb.Th d was also underestimated and moderately correlated (r 2 =0.53-0.59) with micro-CT Tb.Th, independently from the integration time. Stronger correlations, smaller biases and error were found in the scans of the calcaneus ex vivo compared to in situ. Calcaneus trabecular BV/TV d and trabecular microstructure, particularly in the superior region of the calcaneus, can be assessed by HR-pQCT. The highest integration time examined, 200ms, compared best with micro-CT. Weaker correlations for microstructure at inferior regions, and also with lower integration times, might limit the use of the proposed protocol, which warrants further investigation in vivo. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

CT scan exposure in Spanish children and young adults by socioeconomic status: Cross-sectional analysis of cohort data.

PubMed

Bosch de Basea, Magda; Espinosa, Ana; Gil, Mariona; Figuerola, Jordi; Pardina, Marina; Vilar, José; Cardis, Elisabeth

2018-01-01

Recent publications reported that children in disadvantaged areas undergo more CT scanning than others. The present study is aimed to assess the potential differences in CT imaging by socioeconomic status (SES) in Spanish young scanned subjects and if such differences vary with different indicators or different time point SES measurements. The associations between CT scanning and SES, and between the CT scan rate per patient and SES were investigated in the Spanish EPI-CT subcohort. Various SES indicators were studied to determine whether particular SES dimensions were more closely related to the probability of undergoing one or multiple CTs. Comparisons were made with indices based on 2001 and 2011 censuses. We found evidence of socio-economic variation among young people, mainly related to autonomous communities of residence. A slightly higher rate of scans per patient of multiple body parts in the less affluent categories was observed, possibly reflecting a higher rate of accidents and violence in these groups. The number of CT scans per patient was higher both in the most affluent and the most deprived categories and somewhat lower in the intermediate groups. This relation varied with the SES indicator used, with lower CT scans per patients in categories of high unemployment and temporary work, but not depending on categories of unskilled work or illiteracy. The relationship between these indicators and number of CTs in 2011 was different than that seen with the 2001 census, with the number of CTs increasing with higher unemployment. Overall we observed some differences in the SES distribution of scanned patients by Autonomous Community in Spain. There was, however, no major differences in the frequency of CT scans per patient by SES overall, based on the 2001 census. The use of different indicators and of SES data collected at different time points led to different relations between SES and frequency of CT scans, outlining the difficulty of adequately capturing the social and economic dimensions which may affect health and health service utilisation.

CT scan exposure in Spanish children and young adults by socioeconomic status: Cross-sectional analysis of cohort data

PubMed Central

Espinosa, Ana; Gil, Mariona; Figuerola, Jordi; Pardina, Marina; Vilar, José; Cardis, Elisabeth

2018-01-01

Recent publications reported that children in disadvantaged areas undergo more CT scanning than others. The present study is aimed to assess the potential differences in CT imaging by socioeconomic status (SES) in Spanish young scanned subjects and if such differences vary with different indicators or different time point SES measurements. The associations between CT scanning and SES, and between the CT scan rate per patient and SES were investigated in the Spanish EPI-CT subcohort. Various SES indicators were studied to determine whether particular SES dimensions were more closely related to the probability of undergoing one or multiple CTs. Comparisons were made with indices based on 2001 and 2011 censuses. We found evidence of socio-economic variation among young people, mainly related to autonomous communities of residence. A slightly higher rate of scans per patient of multiple body parts in the less affluent categories was observed, possibly reflecting a higher rate of accidents and violence in these groups. The number of CT scans per patient was higher both in the most affluent and the most deprived categories and somewhat lower in the intermediate groups. This relation varied with the SES indicator used, with lower CT scans per patients in categories of high unemployment and temporary work, but not depending on categories of unskilled work or illiteracy. The relationship between these indicators and number of CTs in 2011 was different than that seen with the 2001 census, with the number of CTs increasing with higher unemployment. Overall we observed some differences in the SES distribution of scanned patients by Autonomous Community in Spain. There was, however, no major differences in the frequency of CT scans per patient by SES overall, based on the 2001 census. The use of different indicators and of SES data collected at different time points led to different relations between SES and frequency of CT scans, outlining the difficulty of adequately capturing the social and economic dimensions which may affect health and health service utilisation. PMID:29723272

An electron beam linear scanning mode for industrial limited-angle nano-computed tomography.

PubMed

Wang, Chengxiang; Zeng, Li; Yu, Wei; Zhang, Lingli; Guo, Yumeng; Gong, Changcheng

2018-01-01

Nano-computed tomography (nano-CT), which utilizes X-rays to research the inner structure of some small objects and has been widely utilized in biomedical research, electronic technology, geology, material sciences, etc., is a high spatial resolution and non-destructive research technique. A traditional nano-CT scanning model with a very high mechanical precision and stability of object manipulator, which is difficult to reach when the scanned object is continuously rotated, is required for high resolution imaging. To reduce the scanning time and attain a stable and high resolution imaging in industrial non-destructive testing, we study an electron beam linear scanning mode of nano-CT system that can avoid mechanical vibration and object movement caused by the continuously rotated object. Furthermore, to further save the scanning time and study how small the scanning range could be considered with acceptable spatial resolution, an alternating iterative algorithm based on ℓ 0 minimization is utilized to limited-angle nano-CT reconstruction problem with the electron beam linear scanning mode. The experimental results confirm the feasibility of the electron beam linear scanning mode of nano-CT system.

An electron beam linear scanning mode for industrial limited-angle nano-computed tomography

NASA Astrophysics Data System (ADS)

Wang, Chengxiang; Zeng, Li; Yu, Wei; Zhang, Lingli; Guo, Yumeng; Gong, Changcheng

2018-01-01

Nano-computed tomography (nano-CT), which utilizes X-rays to research the inner structure of some small objects and has been widely utilized in biomedical research, electronic technology, geology, material sciences, etc., is a high spatial resolution and non-destructive research technique. A traditional nano-CT scanning model with a very high mechanical precision and stability of object manipulator, which is difficult to reach when the scanned object is continuously rotated, is required for high resolution imaging. To reduce the scanning time and attain a stable and high resolution imaging in industrial non-destructive testing, we study an electron beam linear scanning mode of nano-CT system that can avoid mechanical vibration and object movement caused by the continuously rotated object. Furthermore, to further save the scanning time and study how small the scanning range could be considered with acceptable spatial resolution, an alternating iterative algorithm based on ℓ0 minimization is utilized to limited-angle nano-CT reconstruction problem with the electron beam linear scanning mode. The experimental results confirm the feasibility of the electron beam linear scanning mode of nano-CT system.

SU-G-206-08: How Should Focal Spot Be Chosen for Optimized CT Imaging with Dose Modulation?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bache, S; Liu, X; Rong, J

Purpose: To choose the preferred focal spot for achieving optimized CT image quality with balanced tube heating considerations. Methods: An anthropomorphic pelvic phantom was scanned using a GE Discovery CT750 HD at 120 and 140kVp, 0.8s rotation time, and pitch of 0.984. “Smart mA” was enabled to simulate a routine abdomen–pelvis CT scan. Permissible mA values at 120 and 140 kVp were obtained from the Serial Load Rating table (for mimicking a busy CT clinical operation) in the scanner Technical Reference Manual. At each kVp station and two Noise Index levels, the mA Upper Limit was set above/below the permissiblemore » mA values. Scanned mA values and focal spot (FS) used were obtained from the DICOM header of each image, and the FS-mA relationship was analyzed. For visual confirmation beyond recorded FS information, a CatPhan with a fat-ring attached for mimicking patient size/shape was scanned at 120kVp. A group of radiologists/physicists compared a pair of CatPhan images qualitatively. Lastly, a number of patient cases were evaluated to confirm the FS-mA relationship. Results: When preset Upper Limit values were above the permissible mA values, the Large FS (labeled 1.2) was used in scans, even if the maximum scanned mA values were much lower than the permissible values at both 120 and 140 kVp. Otherwise the Small FS (labeled 0.7) was used. Visual evaluation of the high contrast module of CatPhan and additional analysis of patient cases further confirmed that the preset Upper Limit determines which focal spot is to be used, not the actual maximum mA value to be scanned. Conclusion: Specific FS can be selected by setting up appropriate mA Upper Limit in a protocol. CT protocols could be optimized by selecting appropriate FS for improving patient image quality, especially benefiting the small size and pediatric patients.« less

Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

PubMed

Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

2010-03-01

The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry.

MR to CT registration of brains using image synthesis

NASA Astrophysics Data System (ADS)

Roy, Snehashis; Carass, Aaron; Jog, Amod; Prince, Jerry L.; Lee, Junghoon

2014-03-01

Computed tomography (CT) is the preferred imaging modality for patient dose calculation for radiation therapy. Magnetic resonance (MR) imaging (MRI) is used along with CT to identify brain structures due to its superior soft tissue contrast. Registration of MR and CT is necessary for accurate delineation of the tumor and other structures, and is critical in radiotherapy planning. Mutual information (MI) or its variants are typically used as a similarity metric to register MRI to CT. However, unlike CT, MRI intensity does not have an accepted calibrated intensity scale. Therefore, MI-based MR-CT registration may vary from scan to scan as MI depends on the joint histogram of the images. In this paper, we propose a fully automatic framework for MR-CT registration by synthesizing a synthetic CT image from MRI using a co-registered pair of MR and CT images as an atlas. Patches of the subject MRI are matched to the atlas and the synthetic CT patches are estimated in a probabilistic framework. The synthetic CT is registered to the original CT using a deformable registration and the computed deformation is applied to the MRI. In contrast to most existing methods, we do not need any manual intervention such as picking landmarks or regions of interests. The proposed method was validated on ten brain cancer patient cases, showing 25% improvement in MI and correlation between MR and CT images after registration compared to state-of-the-art registration methods.

Computed tomography of ball pythons (Python regius) in curled recumbency.

PubMed

Hedley, Joanna; Eatwell, Kevin; Schwarz, Tobias

2014-01-01

Anesthesia and tube restraint methods are often required for computed tomography (CT) of snakes due to their natural tendency to curl up. However, these restraint methods may cause animal stress. The aim of this study was to determine whether the CT appearance of the lungs differs for ball pythons in a curled position vs. tube restraint. Whole body CT was performed on ten clinically healthy ball pythons, first in curled and then in straight positions restrained in a tube. Curved multiplanar reformatted (MPR) lung images from curled position scans were compared with standard MPR lung images from straight position scans. Lung attenuation and thickness were measured at three locations for each scan. Time for positioning and scanning was 12 ± 5 min shorter for curled snakes compared to tube restraint. Lung parenchyma thickness and attenuation declined from cranial to caudal on both straight and curled position images. Mean lung parenchyma thickness was greater in curled images at locations 1 (P = 0.048) and 3 (P = 0.044). Mean lung parenchyma thickness decreased between location 1 and 2 by 86-87% (straight: curled) and between location 1 and 3 by 51-50% (straight: curled). Mean lung attenuation at location 1 was significantly greater on curled position images than tube restraint images (P = 0.043). Findings indicated that CT evaluation of the lungs is feasible for ball pythons positioned in curled recumbency if curved MPR is available. However, lung parenchyma thickness and attenuation in some locations may vary from those acquired using tube restraint. © 2014 American College of Veterinary Radiology.

Graph cuts and neural networks for segmentation and porosity quantification in Synchrotron Radiation X-ray μCT of an igneous rock sample.

PubMed

Meneses, Anderson Alvarenga de Moura; Palheta, Dayara Bastos; Pinheiro, Christiano Jorge Gomes; Barroso, Regina Cely Rodrigues

2018-03-01

X-ray Synchrotron Radiation Micro-Computed Tomography (SR-µCT) allows a better visualization in three dimensions with a higher spatial resolution, contributing for the discovery of aspects that could not be observable through conventional radiography. The automatic segmentation of SR-µCT scans is highly valuable due to its innumerous applications in geological sciences, especially for morphology, typology, and characterization of rocks. For a great number of µCT scan slices, a manual process of segmentation would be impractical, either for the time expended and for the accuracy of results. Aiming the automatic segmentation of SR-µCT geological sample images, we applied and compared Energy Minimization via Graph Cuts (GC) algorithms and Artificial Neural Networks (ANNs), as well as the well-known K-means and Fuzzy C-Means algorithms. The Dice Similarity Coefficient (DSC), Sensitivity and Precision were the metrics used for comparison. Kruskal-Wallis and Dunn's tests were applied and the best methods were the GC algorithms and ANNs (with Levenberg-Marquardt and Bayesian Regularization). For those algorithms, an approximate Dice Similarity Coefficient of 95% was achieved. Our results confirm the possibility of usage of those algorithms for segmentation and posterior quantification of porosity of an igneous rock sample SR-µCT scan. Copyright © 2017 Elsevier Ltd. All rights reserved.

Limiting CT radiation dose in children with craniosynostosis: phantom study using model-based iterative reconstruction.

PubMed

Kaasalainen, Touko; Palmu, Kirsi; Lampinen, Anniina; Reijonen, Vappu; Leikola, Junnu; Kivisaari, Riku; Kortesniemi, Mika

2015-09-01

Medical professionals need to exercise particular caution when developing CT scanning protocols for children who require multiple CT studies, such as those with craniosynostosis. To evaluate the utility of ultra-low-dose CT protocols with model-based iterative reconstruction techniques for craniosynostosis imaging. We scanned two pediatric anthropomorphic phantoms with a 64-slice CT scanner using different low-dose protocols for craniosynostosis. We measured organ doses in the head region with metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters. Numerical simulations served to estimate organ and effective doses. We objectively and subjectively evaluated the quality of images produced by adaptive statistical iterative reconstruction (ASiR) 30%, ASiR 50% and Veo (all by GE Healthcare, Waukesha, WI). Image noise and contrast were determined for different tissues. Mean organ dose with the newborn phantom was decreased up to 83% compared to the routine protocol when using ultra-low-dose scanning settings. Similarly, for the 5-year phantom the greatest radiation dose reduction was 88%. The numerical simulations supported the findings with MOSFET measurements. The image quality remained adequate with Veo reconstruction, even at the lowest dose level. Craniosynostosis CT with model-based iterative reconstruction could be performed with a 20-μSv effective dose, corresponding to the radiation exposure of plain skull radiography, without compromising required image quality.

Automated Facial Recognition of Computed Tomography-Derived Facial Images: Patient Privacy Implications.

PubMed

Parks, Connie L; Monson, Keith L

2017-04-01

The recognizability of facial images extracted from publically available medical scans raises patient privacy concerns. This study examined how accurately facial images extracted from computed tomography (CT) scans are objectively matched with corresponding photographs of the scanned individuals. The test subjects were 128 adult Americans ranging in age from 18 to 60 years, representing both sexes and three self-identified population (ancestral descent) groups (African, European, and Hispanic). Using facial recognition software, the 2D images of the extracted facial models were compared for matches against five differently sized photo galleries. Depending on the scanning protocol and gallery size, in 6-61 % of the cases, a correct life photo match for a CT-derived facial image was the top ranked image in the generated candidate lists, even when blind searching in excess of 100,000 images. In 31-91 % of the cases, a correct match was located within the top 50 images. Few significant differences (p > 0.05) in match rates were observed between the sexes or across the three age cohorts. Highly significant differences (p < 0.01) were, however, observed across the three ancestral cohorts and between the two CT scanning protocols. Results suggest that the probability of a match between a facial image extracted from a medical scan and a photograph of the individual is moderately high. The facial image data inherent in commonly employed medical imaging modalities may need to consider a potentially identifiable form of "comparable" facial imagery and protected as such under patient privacy legislation.

Imaging of acute mesenteric ischemia using multidetector CT and CT angiography in a porcine model.

PubMed

Rosow, David E; Sahani, Dushyant; Strobel, Oliver; Kalva, Sanjeeva; Mino-Kenudson, Mari; Holalkere, Nagaraj S; Alsfasser, Guido; Saini, Sanjay; Lee, Susanna I; Mueller, Peter R; Fernández-del Castillo, Carlos; Warshaw, Andrew L; Thayer, Sarah P

2005-12-01

Acute mesenteric ischemia, a frequently lethal disease, requires prompt diagnosis and intervention for favorable clinical outcomes. This goal remains elusive due, in part, to lack of a noninvasive and accurate imaging study. Traditional angiography is the diagnostic gold standard but is invasive and costly. Computed tomography (CT) is readily available and noninvasive but has shown variable success in diagnosing this disease. The faster scanning time of multidetector row CT (M.D.CT) greatly facilitates the use of CT angiography (CTA) in the clinical setting. We sought to determine whether M.D.CT-CTA could accurately demonstrate vascular anatomy and capture the earliest stages of mesenteric ischemia in a porcine model. Pigs underwent embolization of branches of the superior mesenteric artery, then imaging by M.D.CT-CTA with three-dimensional reconstruction protocols. After scanning, diseased bowel segments were surgically resected and pathologically examined. Multidetector row CT and CT angiography reliably defined normal and occluded mesenteric vessels in the pig. It detected early changes of ischemia including poor arterial enhancement and venous dilatation, which were seen in all ischemic animals. The radiographic findings--compared with pathologic diagnoses-- predicted ischemia, with a positive predictive value of 92%. These results indicate that M.D.CT-CTA holds great promise for the early detection necessary for successful treatment of acute mesenteric ischemia.

Comparative analysis of semantic localization accuracies between adult and pediatric DICOM CT images

NASA Astrophysics Data System (ADS)

Robertson, Duncan; Pathak, Sayan D.; Criminisi, Antonio; White, Steve; Haynor, David; Chen, Oliver; Siddiqui, Khan

2012-02-01

Existing literature describes a variety of techniques for semantic annotation of DICOM CT images, i.e. the automatic detection and localization of anatomical structures. Semantic annotation facilitates enhanced image navigation, linkage of DICOM image content and non-image clinical data, content-based image retrieval, and image registration. A key challenge for semantic annotation algorithms is inter-patient variability. However, while the algorithms described in published literature have been shown to cope adequately with the variability in test sets comprising adult CT scans, the problem presented by the even greater variability in pediatric anatomy has received very little attention. Most existing semantic annotation algorithms can only be extended to work on scans of both adult and pediatric patients by adapting parameters heuristically in light of patient size. In contrast, our approach, which uses random regression forests ('RRF'), learns an implicit model of scale variation automatically using training data. In consequence, anatomical structures can be localized accurately in both adult and pediatric CT studies without the need for parameter adaptation or additional information about patient scale. We show how the RRF algorithm is able to learn scale invariance from a combined training set containing a mixture of pediatric and adult scans. Resulting localization accuracy for both adult and pediatric data remains comparable with that obtained using RRFs trained and tested using only adult data.

Computed tomography automatic exposure control techniques in 18F-FDG oncology PET-CT scanning.

PubMed

Iball, Gareth R; Tout, Deborah

2014-04-01

Computed tomography (CT) automatic exposure control (AEC) systems are now used in all modern PET-CT scanners. A collaborative study was undertaken to compare AEC techniques of the three major PET-CT manufacturers for fluorine-18 fluorodeoxyglucose half-body oncology imaging. An audit of 70 patients was performed for half-body CT scans taken on a GE Discovery 690, Philips Gemini TF and Siemens Biograph mCT (all 64-slice CT). Patient demographic and dose information was recorded and image noise was calculated as the SD of Hounsfield units in the liver. A direct comparison of the AEC systems was made by scanning a Rando phantom on all three systems for a range of AEC settings. The variation in dose and image quality with patient weight was significantly different for all three systems, with the GE system showing the largest variation in dose with weight and Philips the least. Image noise varied with patient weight in Philips and Siemens systems but was constant for all weights in GE. The z-axis mA profiles from the Rando phantom demonstrate that these differences are caused by the nature of the tube current modulation techniques applied. The mA profiles varied considerably according to the AEC settings used. CT AEC techniques from the three manufacturers yield significantly different tube current modulation patterns and hence deliver different doses and levels of image quality across a range of patient weights. Users should be aware of how their system works and of steps that could be taken to optimize imaging protocols.

Technical note: estimating absorbed doses to the thyroid in CT.

PubMed

Huda, Walter; Magill, Dennise; Spampinato, Maria V

2011-06-01

To describe a method for estimating absorbed doses to the thyroid in patients undergoing neck CT examinations. Thyroid doses in anthropomorphic phantoms were obtained for all 23 scanner dosimetry data sets in the ImPACT CT patient dosimetry calculator. Values of relative thyroid dose [R(thy)(L)], defined as the thyroid dose for a given scan length (L) divided by the corresponding thyroid dose for a whole body scan, were determined for neck CT scans. Ratios of the maximum thyroid dose to the corresponding CTDI(vol) and [D'(thy)], were obtained for two phantom diameters. The mass-equivalent water cylinder of any patient can be derived from the neck cross-sectional area and the corresponding average Hounsfield Unit, and compared to the 16.5-cm diameter water cylinder that models the ImPACT anthropomorphic phantom neck. Published values of relative doses in water cylinders of varying diameter were used to adjust thyroid doses in the anthropomorphic phantom to those of any sized patient. Relative thyroid doses R(thy)(L) increase to unity with increasing scan length and with very small difference between scanners. A 10-cm scan centered on the thyroid would result in a dose that is, nearly 90% of the thyroid dose from a whole body scan when performed using the constant radiographic techniques. At 120 kV, the average value of D'(thy) for the 16-cm diameter was 1.17 +/- 0.05 and was independent of CT vendor and year of CT scanner, and choice of x-ray tube voltage. The corresponding average value of D'(thy) in the 32-cm diameter phantom was 2.28 +/- 0.22 and showed marked variations depending on vendor, year of introduction into clinical practice as well as x-ray tube voltage. At 120 kV, a neck equivalent to a 10-cm diameter cylinder of water would have thyroid doses 36% higher than those in the ImPACT phantom, whereas a neck equivalent to a 25-cm cylinder diameter would have thyroid doses 35% lower. Patient thyroid doses can be estimated by taking into account the amount of radiation used to perform the CT examination (CTDI(vol)) and accounting for scan length and patient anatomy (i.e., neck diameter) at the thyroid location.

Adaptive Quantification and Longitudinal Analysis of Pulmonary Emphysema with a Hidden Markov Measure Field Model

PubMed Central

Häme, Yrjö; Angelini, Elsa D.; Hoffman, Eric A.; Barr, R. Graham; Laine, Andrew F.

2014-01-01

The extent of pulmonary emphysema is commonly estimated from CT images by computing the proportional area of voxels below a predefined attenuation threshold. However, the reliability of this approach is limited by several factors that affect the CT intensity distributions in the lung. This work presents a novel method for emphysema quantification, based on parametric modeling of intensity distributions in the lung and a hidden Markov measure field model to segment emphysematous regions. The framework adapts to the characteristics of an image to ensure a robust quantification of emphysema under varying CT imaging protocols and differences in parenchymal intensity distributions due to factors such as inspiration level. Compared to standard approaches, the present model involves a larger number of parameters, most of which can be estimated from data, to handle the variability encountered in lung CT scans. The method was used to quantify emphysema on a cohort of 87 subjects, with repeated CT scans acquired over a time period of 8 years using different imaging protocols. The scans were acquired approximately annually, and the data set included a total of 365 scans. The results show that the emphysema estimates produced by the proposed method have very high intra-subject correlation values. By reducing sensitivity to changes in imaging protocol, the method provides a more robust estimate than standard approaches. In addition, the generated emphysema delineations promise great advantages for regional analysis of emphysema extent and progression, possibly advancing disease subtyping. PMID:24759984

4D computed tomography scans for conformal thoracic treatment planning: is a single scan sufficient to capture thoracic tumor motion?

NASA Astrophysics Data System (ADS)

Tseng, Yolanda D.; Wootton, Landon; Nyflot, Matthew; Apisarnthanarax, Smith; Rengan, Ramesh; Bloch, Charles; Sandison, George; St. James, Sara

2018-01-01

Four dimensional computed tomography (4DCT) scans are routinely used in radiation therapy to determine the internal treatment volume for targets that are moving (e.g. lung tumors). The use of these studies has allowed clinicians to create target volumes based upon the motion of the tumor during the imaging study. The purpose of this work is to determine if a target volume based on a single 4DCT scan at simulation is sufficient to capture thoracic motion. Phantom studies were performed to determine expected differences between volumes contoured on 4DCT scans and those on the evaluation CT scans (slow scans). Evaluation CT scans acquired during treatment of 11 patients were compared to the 4DCT scans used for treatment planning. The images were assessed to determine if the target remained within the target volume determined during the first 4DCT scan. A total of 55 slow scans were compared to the 11 planning 4DCT scans. Small differences were observed in phantom between the 4DCT volumes and the slow scan volumes, with a maximum of 2.9%, that can be attributed to minor differences in contouring and the ability of the 4DCT scan to adequately capture motion at the apex and base of the motion trajectory. Larger differences were observed in the patients studied, up to a maximum volume difference of 33.4%. These results demonstrate that a single 4DCT scan is not adequate to capture all thoracic motion throughout treatment.

Potential for adult-based epidemiological studies to characterize overall cancer risks associated with a lifetime of CT scans.

PubMed

Shuryak, Igor; Lubin, Jay H; Brenner, David J

2014-06-01

Recent epidemiological studies have suggested that radiation exposure from pediatric CT scanning is associated with small excess cancer risks. However, the majority of CT scans are performed on adults, and most radiation-induced cancers appear during middle or old age, in the same age range as background cancers. Consequently, a logical next step is to investigate the effects of CT scanning in adulthood on lifetime cancer risks by conducting adult-based, appropriately designed epidemiological studies. Here we estimate the sample size required for such studies to detect CT-associated risks. This was achieved by incorporating different age-, sex-, time- and cancer type-dependent models of radiation carcinogenesis into an in silico simulation of a population-based cohort study. This approach simulated individual histories of chest and abdominal CT exposures, deaths and cancer diagnoses. The resultant sample sizes suggest that epidemiological studies of realistically sized cohorts can detect excess lifetime cancer risks from adult CT exposures. For example, retrospective analysis of CT exposure and cancer incidence data from a population-based cohort of 0.4 to 1.3 million (depending on the carcinogenic model) CT-exposed UK adults, aged 25-65 in 1980 and followed until 2015, provides 80% power for detecting cancer risks from chest and abdominal CT scans.

The Beatles, the Nobel Prize, and CT scanning of the chest.

PubMed

Goodman, Lawrence R

2010-01-01

From its first test scan on a mouse, in 1967, to current medical practice, the CT scanner has become a core imaging tool in thoracic diagnosis. Initially financed by money from Beatles' record sales, the first patient scan was performed in 1971. Only 8 years later, a Nobel Prize in Physics and Medicine was awarded to Hounsfield and Cormack for their discovery. This article traces the history of CT scanner development and how each technical advance expanded chest diagnostic frontiers. Chest imaging now accounts for 30% of all CT scanning.

Trends and patterns of computed tomography scan use among children in The Netherlands: 1990-2012.

PubMed

Meulepas, Johanna M; Smets, Anne M J B; Nievelstein, Rutger A J; Gradowska, Patrycja; Verbeke, Jonathan; Holscher, Herma C; Rutten, Matthieu J C M; Kieft, Mariëtte; Ronckers, Cécile M; Hauptmann, Michael

2017-06-01

To evaluate trends and patterns in CT usage among children (aged 0-17 years) in The Netherlands during the period 1990-2012. Lists of electronically archived paediatric CT scans were requested from the Radiology Information Systems (RIS) of Dutch hospitals which reported >10 paediatric CT scans annually in a survey conducted in 2010. Data included patient identification, birth date, gender, scan date and body part scanned. For non-participating hospitals and for years prior to electronic archiving in some participating hospitals, data were imputed by calendar year and hospital type (academic, general with <500 beds, general with ≥ 500 beds). Based on 236,066 CT scans among 146,368 patients performed between 1990 and 2012, estimated annual numbers of paediatric CT scans in The Netherlands increased from 7,731 in 1990 to 26,023 in 2012. More than 70 % of all scans were of the head and neck. During the last decade, substantial increases of more than 5 % per year were observed in general hospitals with fewer than 500 beds and among children aged 10 years or older. The estimated number of paediatric CT scans has more than tripled in The Netherlands during the last two decades. • Paediatric CT in The Netherlands has tripled during the last two decades. • The number of paediatric CTs increased through 2012 in general hospitals. • Paediatric CTs continued to increase among children aged 10 years or older.

Planning the Breast Boost: Comparison of Three Techniques and Evolution of Tumor Bed During Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hepel, Jaroslaw T.; Department of Radiation Oncology, Brown University, Rhode Island Hospital, Providence, RI; Evans, Suzanne B.

2009-06-01

Purpose: To evaluate the accuracy of two clinical techniques for electron boost planning compared with computed tomography (CT)-based planning. Additionally, we evaluated the tumor bed characteristics at whole breast planning and boost planning. Methods and Materials: A total of 30 women underwent tumor bed boost planning within 2 weeks of completing whole breast radiotherapy using three planning techniques: scar-based planning, palpation/clinical-based planning, and CT-based planning. The plans were analyzed for dosimetric coverage of the CT-delineated tumor bed. The cavity visualization score was used to define the CT-delineated tumor bed as well or poorly defined. Results: Scar-based planning resulted in inferiormore » tumor bed coverage compared with CT-based planning, with the minimal dose received by 90% of the target volume >90% in 53% and a geographic miss in 53%. The results of palpation/clinical-based planning were significantly better: 87% and 10% for the minimal dose received by 90% of the target volume >90% and geographic miss, respectively. Of the 30 tumor beds, 16 were poorly defined by the cavity visualization score. Of these 16, 8 were well demarcated by the surgical clips. The evaluation of the 22 well-defined tumor beds revealed similar results. A comparison of the tumor bed volume from the initial planning CT scan to the boost planning CT scan revealed a decrease in size in 77% of cases. The mean decrease in volume was 52%. Conclusion: The results of our study have shown that CT-based planning allows for optimal tumor bed coverage compared with clinical and scar-based approaches. However, in the setting of a poorly visualized cavity on CT without surgical clips, palpation/clinical-based planning can help delineate the appropriate target volumes and is superior to scar-based planning. CT simulation at boost planning could allow for a reduction in the boost volumes.« less

Are CT scans obtained at referring institutions justified prior to transfer to a pediatric trauma center?

PubMed

Benedict, Leo Andrew; Paulus, Jessica K; Rideout, Leslie; Chwals, Walter J

2014-01-01

To assess whether pediatric trauma patients initially evaluated at referring institutions met Massachusetts statewide trauma field triage criteria for stabilization and immediate transfer to a Pediatric Trauma Center (PTC) without pre-transfer CT imaging. A 3-year retrospective cohort study was completed at our level 1 PTC. Patients with CT imaging at referring institutions were classified according to a triage scheme based on Massachusetts statewide trauma field triage criteria. Demographic data and injury profile characteristics were abstracted from patient medical records and our pediatric trauma registry. A total of 262 patients with 413 CT scans were reviewed from 2008 to 2011. 172 patients scanned (66%, 95% CI: 60%, 71%) met criteria for immediate transfer to a pediatric trauma center. Notably, 110 scans (27% of the total performed at referring institutions) were duplicated within four hours upon arrival to our PTC. GCS score <14 (45%) was the most common requirement for transfer, and CT scan of the head was the most frequent scan obtained (53%). The majority of pediatric trauma patients were subjected to CT scans at referring institutions despite meeting Massachusetts trauma triage guidelines that call for stabilization and immediate transfer to a pediatric trauma center without any CT imaging. © 2014.

Can CT-based patient-matched instrumentation achieve consistent rotational alignment in knee arthroplasty?

PubMed

Tibesku, C O; Innocenti, B; Wong, P; Salehi, A; Labey, L

2012-02-01

Long-term success of contemporary total knee replacements relies to a large extent on proper implant alignment. This study was undertaken to test whether specimen-matched cutting blocks based on computed axial tomography (CT) scans could provide accurate rotational alignment of the femoral component. CT scans of five fresh frozen full leg cadaver specimens, equipped with infrared reflective markers, were used to produce a specimen-matched femoral cutting block. Using those blocks, the bone cuts were made to implant a bi-compartmental femoral component. Rotational alignment of the components in the horizontal plane was determined using an optical measurement system and compared with all relevant rotational reference axes identified on the CT scans. Average rotational alignment for the bi-compartmental component in the horizontal plane was 1.9° (range 0°-6.3°; standard deviation 2.6°). One specimen that showed the highest deviation from the planned alignment also featured a completely degraded medial articular surface. The CT-based specimen-matched cutting blocks achieved good rotational alignment accuracy except for one specimen with badly damaged cartilage. In such cases, imaging techniques that visualize the cartilage layer might be more suitable to design cutting blocks, as they will provide a better fit and increased surface support.

Brain early infarct detection using gamma correction extreme-level eliminating with weighting distribution.

PubMed

Teh, V; Sim, K S; Wong, E K

2016-11-01

According to the statistic from World Health Organization (WHO), stroke is one of the major causes of death globally. Computed tomography (CT) scan is one of the main medical diagnosis system used for diagnosis of ischemic stroke. CT scan provides brain images in Digital Imaging and Communication in Medicine (DICOM) format. The presentation of CT brain images is mainly relied on the window setting (window center and window width), which converts an image from DICOM format into normal grayscale format. Nevertheless, the ordinary window parameter could not deliver a proper contrast on CT brain images for ischemic stroke detection. In this paper, a new proposed method namely gamma correction extreme-level eliminating with weighting distribution (GCELEWD) is implemented to improve the contrast on CT brain images. GCELEWD is capable of highlighting the hypodense region for diagnosis of ischemic stroke. The performance of this new proposed technique, GCELEWD, is compared with four of the existing contrast enhancement technique such as brightness preserving bi-histogram equalization (BBHE), dualistic sub-image histogram equalization (DSIHE), extreme-level eliminating histogram equalization (ELEHE), and adaptive gamma correction with weighting distribution (AGCWD). GCELEWD shows better visualization for ischemic stroke detection and higher values with image quality assessment (IQA) module. SCANNING 38:842-856, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Audit of demand for after-hours CT scanning services in RANZCR-accredited training departments.

PubMed

Goergen, Stacy K; Grimm, Jane; Paul, Eldho; Fabiny, Robert; Lee, Wai Kit; Blome, Steven; Zhou, Kim; Munro, Philip L

2016-02-01

The aims of this study were to measure: (i) the growth in after-hours emergency department--referred CT (ED-CT) performed in accredited training departments between 2011 and 2013; (ii) the growth in ED CT relative to growth in ED presentations at the same hospitals; and (iii) trainee workload resulting from after-hours ED CT. Ethics approval was obtained for all participating sites. Accredited training facilities in Australia and New Zealand with three or more trainees and serving one or more EDs were invited to participate (N = 32). Four nights were surveyed between August and December 2013. For data collection, the number of ED patients having one or more CT scans; ED CT scan total images; non-contrast head CTs; and ED patients (total and categories 1 and 2) attending the ED in the preceding 24 h and first half of calendar year were collected for 2013 and corresponding days in 2012 and 2011. Trainee staffing levels were measured. Eleven of 32 sites provided data for all four nights and 14 of 32 for one or more nights. A 15.7% increase in number of ED CTs between 1700 and 2200 h and 16.8% increase between 2201 and 0730 h occurred in the 2 years between 2011 and 2013 compared with a 6.9% increase in overall ED and 26% increase in categories 1 and 2 presentations over the same period. The number of CT images, however, increased 23%. Growth in demand by EDs for after-hours CT services has implications for service provision and trainee workloads in Royal Australian and New Zealand College of Radiologists-accredited training departments. © 2015 The Royal Australian and New Zealand College of Radiologists.

Intravenous volume tomographic pulmonary angiography imaging

NASA Astrophysics Data System (ADS)

Ning, Ruola; Strang, John G.; Chen, Biao; Conover, David L.; Yu, Rongfeng

1999-05-01

This study presents a new intravenous (IV) tomographic angiography imaging technique, called intravenous volume tomographic digital angiography (VTDA) for cross sectional pulmonary angiography. While the advantages of IV-VTDA over spiral CT in terms of volume scanning time and resolution have been validated and reported in our previous papers for head and neck vascular imaging, the superiority of IV-VTDA over spiral CT for cross sectional pulmonary angiography has not been explored yet. The purpose of this study is to demonstrate the advantage of isotropic resolution of IV-VTDA in the x, y and z directions through phantom and animal studies, and to explore its clinical application for detecting clots in pulmonary angiography. A prototype image intensifier-based VTDA imaging system has been designed and constructed by modifying a GE 8800 CT scanner. This system was used for a series of phantom and dog studies. A pulmonary vascular phantom was designed and constructed. The phantom was scanned using the prototype VTDA system for direct 3D reconstruction. Then the same phantom was scanned using a GE CT/i spiral CT scanner using the routine pulmonary CT angiography protocols. IV contrast injection and volume scanning protocols were developed during the dog studies. Both VTDA reconstructed images and spiral CT images of the specially designed phantom were analyzed and compared. The detectability of simulated vessels and clots was assessed as the function of iodine concentration levels, oriented angles, and diameters of the vessels and clots. A set of 3D VTDA reconstruction images of dog pulmonary arteries was obtained with different IV injection rates and isotropic resolution in the x, y and z directions. The results of clot detection studies in dog pulmonary arteries have also been shown. This study presents a new tomographic IV angiography imaging technique for cross sectional pulmonary angiography. The results of phantom and animal studies indicate that IV-VTDA is superior to spiral CT for cross sectional pulmonary angiography.

Whole-body CT in polytrauma patients: The effect of arm position on abdominal image quality when using a human phantom

NASA Astrophysics Data System (ADS)

Jeon, Pil-Hyun; Kim, Hee-Joung; Lee, Chang-Lae; Kim, Dae-Hong; Lee, Won-Hyung; Jeon, Sung-Su

2012-06-01

For a considerable number of emergency computed tomography (CT) scans, patients are unable to position their arms above their head due to traumatic injuries. The arms-down position has been shown to reduce image quality with beam-hardening artifacts in the dorsal regions of the liver, spleen, and kidneys, rendering these images non-diagnostic. The purpose of this study was to evaluate the effect of arm position on the image quality in patients undergoing whole-body CT. We acquired CT scans with various acquisition parameters at voltages of 80, 120, and 140 kVp and an increasing tube current from 200 to 400 mAs in 50 mAs increments. The image noise and the contrast assessment were considered for quantitative analyses of the CT images. The image noise (IN), the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and the coefficient of variation (COV) were evaluated. Quantitative analyses of the experiments were performed with CT scans representative of five different arm positions. Results of the CT scans acquired at 120 kVp and 250 mAs showed high image quality in patients with both arms raised above the head (SNR: 12.4, CNR: 10.9, and COV: 8.1) and both arms flexed at the elbows on the chest (SNR: 11.5, CNR: 10.2, and COV: 8.8) while the image quality significantly decreased with both arms in the down position (SNR: 9.1, CNR: 7.6, and COV: 11). Both arms raised, one arm raised, and both arms flexed improved the image quality compared to arms in the down position by reducing beam-hardening and streak artifacts caused by the arms being at the side of body. This study provides optimal methods for achieving higher image quality and lower noise in abdominal CT for trauma patients.

Is there a trend in CT scanning scaphoid nonunions for deformity assessment?-A systematic review.

PubMed

Ten Berg, Paul W L; de Roo, Marieke G A; Maas, Mario; Strackee, Simon D

2017-06-01

The effect of scaphoid nonunion deformity on wrist function is uncertain due to the lack of reliable imaging tools. Advanced three-dimensional (3-D) computed tomography (CT)-based imaging techniques may improve deformity assessment by using a mirrored image of the contralateral intact wrist as anatomic reference. The implementation of such techniques depends on the extent to which conventional CT is currently used in standard practice. The purpose of this systematic review of medical literature was to analyze the trend in CT scanning scaphoid nonunions, either unilaterally or bilaterally. Using Medline and Embase databases, two independent reviewers searched for original full-length clinical articles describing series with at least five patients focusing on reconstructive surgery of scaphoid nonunions with bone grafting and/or fixation, from the years 2000-2015. We excluded reports focusing on only nonunions suspected for avascular necrosis and/or treated with vascularized bone grafting, as their workup often includes magnetic resonance imaging. For data analysis, we evaluated the use of CT scans and distinguished between uni- and bilateral, and pre- and postoperative scans. Seventy-seven articles were included of which 16 were published between 2000 and 2005, 19 between 2006 and 2010, and 42 between 2011 and 2015. For these consecutive intervals, the rates of articles describing the use of pre- and postoperative CT scans increased from 13%, to 16%, to 31%, and from 25%, to 32%, to 52%, respectively. Hereof, only two (3%) articles described the use of bilateral CT scans. There is an evident trend in performing unilateral CT scans before and after reconstructive surgery of a scaphoid nonunion. To improve assessment of scaphoid nonunion deformity using 3-D CT-based imaging techniques, we recommend scanning the contralateral wrist as well. Copyright © 2017 Elsevier B.V. All rights reserved.

68Ga-PSMA PET/CT in the evaluation of bone metastases in prostate cancer.

PubMed

Sachpekidis, Christos; Bäumer, P; Kopka, K; Hadaschik, B A; Hohenfellner, M; Kopp-Schneider, A; Haberkorn, U; Dimitrakopoulou-Strauss, A

2018-06-01

The aims of this retrospective analysis were to compare 68 Ga-PSMA PET findings and low-dose CT findings (120 kV, 30 mA), and to obtain semiquantitative and quantitative 68 Ga-PSMA PET data in patients with prostate cancer (PC) bone metastases. In total, 152 PET/CT scans from 140 patients were evaluated. Of these patients, 30 had previously untreated primary PC, and 110 had biochemical relapse after treatment of primary PC. All patients underwent dynamic PET/CT scanning of the pelvis and lower abdomen as well as whole-body PET/CT with 68 Ga-PSMA-11. The PET/CT scans were analysed qualitatively (visually), semiquantitatively (SUV), and quantitatively based on a two-tissue compartment model and a noncompartmental approach leading to the extraction of the fractal dimension. Differences were considered significant for p values <0.05. In total, 168 68 Ga-PSMA-positive and 113 CT-positive skeletal lesions were detected in 37 patients (8 with primary PC, 29 with biochemical recurrence). Of these 168 lesions, 103 were both 68 Ga-PSMA PET-positive and CT-positive, 65 were only 68 Ga-PSMA-positive, and 10 were only CT-positive. The Yang test showed that there were significantly more 68 Ga-PSMA PET-positive lesions than CT-positive lesions. Association analysis showed that PSA plasma levels were significantly correlated with several 68 Ga-PSMA-11-associated parameters in bone metastases, including the degree of tracer uptake (SUV average and SUV max ), its transport rate from plasma to the interstitial/intracellular compartment (K 1 ), its rate of binding to the PSMA receptor and its internalization (k 3 ), its influx rate (K i ), and its distribution heterogeneity. 68 Ga-PSMA PET/CT is a useful diagnostic tool in the detection of bone metastases in PC. 68 Ga-PSMA PET visualizes more bone metastases than low-dose CT. PSA plasma levels are significantly correlated with several 68 Ga-PSMA PET parameters.

Comparing two quantitative methods for studying remineralization of artificial caries.

PubMed

Lo, E C M; Zhi, Q H; Itthagarun, A

2010-04-01

To compare the detection of changes before and after remineralization of artificial enamel and dentin caries by microCT scanning, polarized light microscopy (PLM) and transverse microradiography (TMR). Fourteen extracted premolars were cut into tooth blocks and painted with an acid-resistant varnish leaving one enamel and one dentin surface exposed. The tooth blocks were immersed into demineralizing solution for 4 days to produce artificial caries-like lesions and scanned by microCT. Then the 14 tooth blocks were randomly allocated into two groups. Seven tooth blocks in Group I were cut longitudinally through the exposed surface into 100-150 microm thick sections and microradiographs were taken. The other seven tooth blocks in Group II were left intact. All the tooth blocks and sections were then immersed into remineralizing solution for 5 days. PLM and TMR of the tooth sections in Group I were taken again. Depth of the lesion on the TMR was measured. Tooth blocks in Group II were scanned by microCT. Mean lesion depth in Group I reduced by 13.0% and 8.2% after remineralization for enamel and dentin, respectively (paired t-test, P<0.001). In Group II, linear attenuation coefficient (LAC) of the region of interest (ROI) increased by 11.1% and 23.8% after remineralization for enamel and dentin lesions, respectively (paired t-test, P<0.001). Both microCT and microradiography are able to detect a change of similar magnitude in the artificial caries lesions after remineralization. MicroCT may be used to substitute TMR and PLM in in vitro studies about caries. Copyright 2010 Elsevier Ltd. All rights reserved.

Reliability of smartphone-based teleradiology for evaluating thoracolumbar spine fractures.

PubMed

Stahl, Ido; Dreyfuss, Daniel; Ofir, Dror; Merom, Lior; Raichel, Michael; Hous, Nir; Norman, Doron; Haddad, Elias

2017-02-01

Timely interpretation of computed tomography (CT) scans is of paramount importance in diagnosing and managing spinal column fractures, which can be devastating. Out-of-hospital, on-call spine surgeons are often asked to evaluate CT scans of patients who have sustained trauma to the thoracolumbar spine to make diagnosis and to determine the appropriate course of urgent treatment. Capturing radiographic scans and video clips from computer screens and sending them as instant messages have become common means of communication between physicians, aiding in triaging and transfer decision-making in orthopedic and neurosurgical emergencies. The present study aimed to compare the reliability of interpreting CT scans viewed by orthopedic surgeons in two ways for diagnosing, classifying, and treatment planning for thoracolumbar spine fractures: (1) captured as video clips from standard workstation-based picture archiving and communication system (PACS) and sent via a smartphone-based instant messaging application for viewing on a smartphone; and (2) viewed directly on a PACS. Reliability and agreement study. Thirty adults with thoracolumbar spine fractures who had been consecutively admitted to the Division of Orthopedic Surgery of a Level I trauma center during 2014. Intraobserver agreement. CT scans were captured by use of an iPhone 6 smartphone from a computer screen displaying PACS. Then by use of the WhatsApp instant messaging application, video clips of the scans were sent to the personal smartphones of five spine surgeons. These evaluators were asked to diagnose, classify, and determine the course of treatment for each case. Evaluation of the cases was repeated 4 weeks later, this time using the standard method of workstation-based PACS. Intraobserver agreement was interpreted based on the value of Cohen's kappa statistic. The study did not receive any outside funding. Intraobserver agreement for determining fracture level was near perfect (κ=0.94). Intraobserver agreement for AO classification, proposed treatment, neural canal penetration, and Denis classification were substantial (κ values, 0.75, 0.73, 0.71, and 0.69, respectively). Intraobserver agreement for loss of vertebral height and kyphosis were moderate (κ values, 0.55 and 0.45, respectively) CONCLUSIONS: Video clips of CT scans can be readily captured by a smartphone from a workstation-based PACS and then transmitted by use of the WhatsApp instant messaging application. Diagnosing, classifying, and proposing treatment of fractures of the thoracic and lumbar spine can be made with equal reliability by evaluating video clips of CT scans transmitted to a smartphone or by the standard method of viewing the CT scan on a workstation-based PACS. Evaluating video clips of CT scans transmitted to a smartphone is a readily accessible, simple, and inexpensive method. We believe that it can be reliably used for consultations between the emergency physicians or orthopedic or neurosurgical residents with offsite, on-call specialists. It might also enable rural orcommunity emergency department physicians to communicate more efficiently and effectively with surgeons in tertiary referral centers. Copyright © 2016 Elsevier Inc. All rights reserved.

Dose reduction of up to 89% while maintaining image quality in cardiovascular CT achieved with prospective ECG gating

NASA Astrophysics Data System (ADS)

Londt, John H.; Shreter, Uri; Vass, Melissa; Hsieh, Jiang; Ge, Zhanyu; Adda, Olivier; Dowe, David A.; Sabllayrolles, Jean-Louis

2007-03-01

We present the results of dose and image quality performance evaluation of a novel, prospective ECG-gated Coronary CT Angiography acquisition mode (SnapShot Pulse, LightSpeed VCT-XT scanner, GE Healthcare, Waukesha, WI), and compare it to conventional retrospective ECG gated helical acquisition in clinical and phantom studies. Image quality phantoms were used to measure noise, slice sensitivity profile, in-plane resolution, low contrast detectability and dose, using the two acquisition modes. Clinical image quality and diagnostic confidence were evaluated in a study of 31 patients scanned with the two acquisition modes. Radiation dose reduction in clinical practice was evaluated by tracking 120 consecutive patients scanned with the prospectively gated scan mode. In the phantom measurements, the prospectively gated mode resulted in equivalent or better image quality measures at dose reductions of up to 89% compared to non-ECG modulated conventional helical scans. In the clinical study, image quality was rated excellent by expert radiologist reviewing the cases, with pathology being identical using the two acquisition modes. The average dose to patients in the clinical practice study was 5.6 mSv, representing 50% reduction compared to a similar patient population scanned with the conventional helical mode.

The Effect of the Presence of EEG Leads on Image Quality in Cerebral Perfusion SPECT and FDG PET/CT.

PubMed

Zhang, Lulu; Yen, Stephanie P; Seltzer, Marc A; Thomas, George P; Willis, Kristen; Siegel, Alan

2018-06-08

Rationale: Cerebral perfusion SPECT and 18 F-FDG PET/CT are commonly performed diagnostic procedures for patients suffering from epilepsy. Individuals receiving these tests are often in-patients undergoing examinations with EEG leads. We have routinely removed these leads before these tests due to concerns that they would lead to imaging artifacts. The leads would then be replaced at the conclusion of the scan. The goal of our study was to determine if the EEG leads actually do cause artifacts that could lead to erroneous scan interpretation or make the scan uninterpretable. Methods: PET/CT with 18 F-FDG and SPECT with technetium-99m ECD were performed on a two dimensional brain phantom. The phantom was scanned with standard leads, CT/MR compatible leads and with no leads. The scans were interpreted by three experienced nuclear medicine physicians who were asked to rank the images by quality and then to determine if they could differentiate each of the scans from a scan in which it was indicated that no leads were present. Results: No differences could be detected between SPECT or PET scans performed without leads or with either set of leads. The standard EEG leads did create an artifact in the CT portion of the PET/CT while the CT/MR compatible leads did not. Conclusion: This phantom study suggest that EEG leads, standard or CT/MR compatible do not need to be removed for SPECT or for PET. Further study evaluating the effect on patients scan would be of value to support this conclusion. Copyright © 2018 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Radiation Dose Reduction by Indication-Directed Focused z-Direction Coverage for Neck CT.

PubMed

Parikh, A K; Shah, C C

2016-06-01

The American College of Radiology-American Society of Neuroradiology-Society for Pediatric Radiology Practice Parameter for a neck CT suggests that coverage should be from the sella to the aortic arch. It also recommends using CT scans judiciously to achieve the clinical objective. Our purpose was to analyze the potential dose reduction by decreasing the scan length of a neck CT and to assess for any clinically relevant information that might be missed from this modified approach. This retrospective study included 126 children who underwent a neck CT between August 1, 2013, and September 30, 2014. Alteration of the scan length for the modified CT was suggested on the topographic image on the basis of the indication of the study, with the reader blinded to the images and the report. The CT dose index volume of the original scan was multiplied by the new scan length to calculate the dose-length product of the modified study. The effective dose was calculated for the original and modified studies by using age-based conversion factors from the American Association of Physicists in Medicine Report No. 96. Decreasing the scan length resulted in an average estimated dose reduction of 47%. The average reduction in scan length was 10.4 cm, decreasing the overall coverage by 48%. The change in scan length did not result in any missed findings that altered management. Of the 27 abscesses in this study, none extended to the mediastinum. All of the lesions in question were completely covered. Decreasing the scan length of a neck CT according to the indication provides a significant savings in radiation dose, while not altering diagnostic ability or management. © 2016 by American Journal of Neuroradiology.

Comparison of Magnetic Resonance Imaging and Computed Tomography for Breast Target Volume Delineation in Prone and Supine Positions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogson, Elise M.; Liverpool and Macarthur Cancer Therapy Centres, Liverpool; Ingham Institute for Applied Medical Research, Liverpool

2016-11-15

Purpose: To determine whether T2-weighted MRI improves seroma cavity (SC) and whole breast (WB) interobserver conformity for radiation therapy purposes, compared with the gold standard of CT, both in the prone and supine positions. Methods and Materials: Eleven observers (2 radiologists and 9 radiation oncologists) delineated SC and WB clinical target volumes (CTVs) on T2-weighted MRI and CT supine and prone scans (4 scans per patient) for 33 patient datasets. Individual observer's volumes were compared using the Dice similarity coefficient, volume overlap index, center of mass shift, and Hausdorff distances. An average cavity visualization score was also determined. Results: Imaging modalitymore » did not affect interobserver variation for WB CTVs. Prone WB CTVs were larger in volume and more conformal than supine CTVs (on both MRI and CT). Seroma cavity volumes were larger on CT than on MRI. Seroma cavity volumes proved to be comparable in interobserver conformity in both modalities (volume overlap index of 0.57 (95% Confidence Interval (CI) 0.54-0.60) for CT supine and 0.52 (95% CI 0.48-0.56) for MRI supine, 0.56 (95% CI 0.53-0.59) for CT prone and 0.55 (95% CI 0.51-0.59) for MRI prone); however, after registering modalities together the intermodality variation (Dice similarity coefficient of 0.41 (95% CI 0.36-0.46) for supine and 0.38 (0.34-0.42) for prone) was larger than the interobserver variability for SC, despite the location typically remaining constant. Conclusions: Magnetic resonance imaging interobserver variation was comparable to CT for the WB CTV and SC delineation, in both prone and supine positions. Although the cavity visualization score and interobserver concordance was not significantly higher for MRI than for CT, the SCs were smaller on MRI, potentially owing to clearer SC definition, especially on T2-weighted MR images.« less

Three-dimensional surface reconstruction for industrial computed tomography

NASA Technical Reports Server (NTRS)

Vannier, M. W.; Knapp, R. H.; Gayou, D. E.; Sammon, N. P.; Butterfield, R. L.; Larson, J. W.

1985-01-01

Modern high resolution medical computed tomography (CT) scanners can produce geometrically accurate sectional images of many types of industrial objects. Computer software has been developed to convert serial CT scans into a three-dimensional surface form, suitable for display on the scanner itself. This software, originally developed for imaging the skull, has been adapted for application to industrial CT scanning, where serial CT scans thrrough an object of interest may be reconstructed to demonstrate spatial relationships in three dimensions that cannot be easily understood using the original slices. The methods of three-dimensional reconstruction and solid modeling are reviewed, and reconstruction in three dimensions from CT scans through familiar objects is demonstrated.

[Clinical application of high-pitch excretory phase images during dual-source CT urography with stellar photon detector].

PubMed

Sun, Hao; Xue, Hua-dan; Jin, Zheng-yu; Wang, Xuan; Chen, Yu; He, Yong-lan; Zhang, Da-ming; Zhu, Liang; Wang, Yun; Qi, Bing; Xu, Kai; Wang, Ming

2014-10-01

To retrospectively evaluate the clinical feasibility of high-pitch excretory phase images during dual-source CT urography with Stellar photon detector. Totally 100 patients received dual-source CT high-pitch urinary excretory phase scanning with Stellar photon detector [80 kV, ref.92 mAs, CARE Dose 4D and CARE kV, pitch of 3.0, filter back projection reconstruction algorithm (FBP)] (group A). Another 100 patients received dual-source CT high-pitch urinary excretory phase scanning with common detector(100 kV, ref.140 mAs, CARE Dose 4D, pitch of 3.0, FBP) (group B). Quantitative measurement of CT value of urinary segments (Hounsfield units), image noise (Hounsfield units), and effective radiation dose (millisievert) were compared using independent-samples t test between two groups. Urinary system subjective opacification scores were compared using Mann-Whitney U test between two groups. There was no significant difference in subjective opacification score of intrarenal collecting system and ureters between two groups (all P>0.05). The group A images yielded significantly higher CT values of all urinary segments (all P<0.01). There was no significant difference in image noise (P>0.05). The effective radiation dose of group A (1.1 mSv) was significantly lower than that of group B (3.79 mSv) (P<0.01). High-pitch low-tube-voltage during excretory phase dual-source CT urography with Stellar photon detector is feasible, with acceptable image noise and lower radiation dose.

Early introduction of direct oral anticoagulants in cardioembolic stroke patients with non-valvular atrial fibrillation.

PubMed

Cappellari, Manuel; Carletti, Monica; Danese, Alessandra; Bovi, Paolo

2016-10-01

Direct oral anticoagulants (DOACs) are superior to warfarin in reduction of the intracranial bleeding risk. The aim of the present study was to assess whether early DOAC introduction (1-3 days after onset) in stroke patients with non-valvular atrial fibrillation (nVAF) may be safe and effective, compared with DOAC introduction after 4-7 days. We conducted a prospective analysis based on data collected from 147 consecutive nVAF patients who started DOAC within 7 days after stroke onset. In all patients, we performed pre-DOAC CT scan 24-36 h after onset and follow-up CT scan at 7 days after DOAC introduction. Outcome measures were post-DOAC intracranial bleeding (new any intracerebral hemorrhage (ICH) in patients with pre-DOAC infarct without hemorrhagic transformation (HT) or expansion of ICH in patients with pre-DOAC infarct with asymptomatic HT) and post-DOAC recurrent ischemic stroke (any new ischemic infarct) on follow-up CT scan. 97 patients started DOAC after 1-3 days and 50 patients started DOAC after 4-7 days. On pre-DOAC CT scan, 132 patients had an infarct without HT and 15 an infarct with asymptomatic HT. On follow-up CT scan, new any ICH was noted in seven patients (asymptomatic in 6) and asymptomatic expansion of ICH in one patient. We found no association between early DOAC introduction and intracranial bleeding. Large infarct remained the only independent predictor of post-DOAC intracranial bleeding. No patients suffered recurrent ischemic stroke after DOAC introduction. Early DOAC introduction might be safe in carefully selected patients with nVAF who experience small- and medium-sized cardioembolic ischemic strokes. Further investigation will be needed.

CT scan (image)

MedlinePlus

CT stands for computerized tomography. In this procedure, a thin X-ray beam is rotated around the ... D image of a section through the body. CT scans are very detailed and provide excellent information ...

Blend Sign on Computed Tomography: Novel and Reliable Predictor for Early Hematoma Growth in Patients With Intracerebral Hemorrhage.

PubMed

Li, Qi; Zhang, Gang; Huang, Yuan-Jun; Dong, Mei-Xue; Lv, Fa-Jin; Wei, Xiao; Chen, Jian-Jun; Zhang, Li-Juan; Qin, Xin-Yue; Xie, Peng

2015-08-01

Early hematoma growth is not uncommon in patients with intracerebral hemorrhage and is an independent predictor of poor functional outcome. The purpose of our study was to report and validate the use of our newly identified computed tomographic (CT) blend sign in predicting early hematoma growth. Patients with intracerebral hemorrhage who underwent baseline CT scan within 6 hours after onset of symptoms were included. The follow-up CT scan was performed within 24 hours after the baseline CT scan. Significant hematoma growth was defined as an increase in hematoma volume of >33% or an absolute increase of hematoma volume of >12.5 mL. The blend sign on admission nonenhanced CT was defined as blending of hypoattenuating area and hyperattenuating region with a well-defined margin. Univariate and multivariable logistic regression analyses were performed to assess the relationship between the presence of the blend sign on nonenhanced admission CT and early hematoma growth. A total of 172 patients were included in our study. Blend sign was observed in 29 of 172 (16.9%) patients with intracerebral hemorrhage on baseline nonenhanced CT scan. Of the 61 patients with hematoma growth, 24 (39.3%) had blend sign on admission CT scan. Interobserver agreement for identifying blend sign was excellent between the 2 readers (κ=0.957). The multivariate logistic regression analysis demonstrated that the time to baseline CT scan, initial hematoma volume, and presence of blend sign on baseline CT scan to be independent predictors of early hematoma growth. The sensitivity, specificity, positive and negative predictive values of blend sign for predicting hematoma growth were 39.3%, 95.5%, 82.7%, and 74.1%, respectively. The CT blend sign could be easily identified on regular nonenhanced CT and is highly specific for predicting hematoma growth. © 2015 American Heart Association, Inc.

Delayed splenic vascular injury after nonoperative management of blunt splenic trauma.

PubMed

Furlan, Alessandro; Tublin, Mitchell E; Rees, Mitchell A; Nicholas, Dederia H; Sperry, Jason L; Alarcon, Louis H

2017-05-01

Delayed splenic vascular injury (DSVI) is traditionally considered a rare, often clinically occult, harbinger of splenic rupture in patients with splenic trauma that are managed conservatively. The purpose of our study was to assess the incidence of DSVI and associated features in patients admitted with blunt splenic trauma and managed nonoperatively. A retrospective analysis was conducted over a 4-y time. Patients admitted with blunt splenic trauma, managed no-operatively and with a follow-up contrast-enhanced computed tomography (CT) scan study during admission were included. The CT scans were reviewed for American Association for the Surgery of Trauma splenic injury score, amount of hemoperitoneum, and presence of DSVI. Logistic regression models were used to investigate the risk factors associated with DSVI. A total of 100 patients (60 men and 40 women) constituted the study group. Follow-up CT scan demonstrated a 23% incidence of DSVI. Splenic artery angiography validated DSVI in 15% of the total patient population. Most DSVIs were detected only on arterial phase CT scan imaging. The American Association for the Surgery of Trauma splenic injury score (odds ratio = 1.73; P = 0.045) and the amount of hemoperitoneum (odds ratio = 1.90; P = 0.023) on admission CT scan were associated with the development of DSVI on follow-up CT scan. DSVI on follow-up CT scan imaging of patients managed nonoperatively after splenic injury is common and associated with splenic injury score assessed on admission CT scan. Copyright © 2016 Elsevier Inc. All rights reserved.

Patient characteristics associated with differences in radiation exposure from pediatric abdomen-pelvis CT scans: a quantile regression analysis.

PubMed

Cooper, Jennifer N; Lodwick, Daniel L; Adler, Brent; Lee, Choonsik; Minneci, Peter C; Deans, Katherine J

2017-06-01

Computed tomography (CT) is a widely used diagnostic tool in pediatric medicine. However, due to concerns regarding radiation exposure, it is essential to identify patient characteristics associated with higher radiation burden from CT imaging, in order to more effectively target efforts towards dose reduction. Our objective was to identify the effects of various demographic and clinical patient characteristics on radiation exposure from single abdomen/pelvis CT scans in children. CT scans performed at our institution between January 2013 and August 2015 in patients under 16 years of age were processed using a software tool that estimates patient-specific organ and effective doses and merges these estimates with data from the electronic health record and billing record. Quantile regression models at the 50th, 75th, and 90th percentiles were used to estimate the effects of patients' demographic and clinical characteristics on effective dose. 2390 abdomen/pelvis CT scans (median effective dose 1.52mSv) were included. Of all characteristics examined, only older age, female gender, higher BMI, and whether the scan was a multiphase exam or an exam that required repeating for movement were significant predictors of higher effective dose at each quantile examined (all p<0.05). The effects of obesity and multiphase or repeat scanning on effective dose were magnified in higher dose scans. Older age, female gender, obesity, and multiphase or repeat scanning are all associated with increased effective dose from abdomen/pelvis CT. Targeted efforts to reduce dose from abdominal CT in these groups should be undertaken. Copyright © 2017 Elsevier Ltd. All rights reserved.

Radiotherapy volume delineation using 18F-FDG-PET/CT modifies gross node volume in patients with oesophageal cancer.

PubMed

Jimenez-Jimenez, E; Mateos, P; Aymar, N; Roncero, R; Ortiz, I; Gimenez, M; Pardo, J; Salinas, J; Sabater, S

2018-05-02

Evidence supporting the use of 18F-FDG-PET/CT in the segmentation process of oesophageal cancer for radiotherapy planning is limited. Our aim was to compare the volumes and tumour lengths defined by fused PET/CT vs. CT simulation. Twenty-nine patients were analyzed. All patients underwent a single PET/CT simulation scan. Two separate GTVs were defined: one based on CT data alone and another based on fused PET/CT data. Volume sizes for both data sets were compared and the spatial overlap was assessed by the Dice similarity coefficient (DSC). The gross tumour volume (GTVtumour) and maximum tumour diameter were greater by PET/CT, and length of primary tumour was greater by CT, but differences were not statistically significant. However, the gross node volume (GTVnode) was significantly greater by PET/CT. The DSC analysis showed excellent agreement for GTVtumour, 0.72, but was very low for GTVnode, 0.25. Our study shows that the volume definition by PET/CT and CT data differs. CT simulation, without taking into account PET/CT information, might leave cancer-involved nodes out of the radiotherapy-delineated volumes.

JOURNAL CLUB: Quantification of Fetal Dose Reduction if Abdominal CT Is Limited to the Top of the Iliac Crests in Pregnant Patients With Trauma.

PubMed

Corwin, Michael T; Seibert, J Anthony; Fananapazir, Ghaneh; Lamba, Ramit; Boone, John M

2016-04-01

The purposes of this study were to correlate fetal z-axis location within the maternal abdomen on CT with gestational age and estimate fetal dose reduction of a study limited to the abdomen only, with its lower aspect at the top of the iliac crests, compared with full abdominopelvic CT in pregnant trauma patients. We performed a study of pregnant patients who underwent CT of the abdomen and pelvis for trauma at a single institution over a 10-year period. The inferior aspect of maternal liver, spleen, gallbladder, pancreas, adrenals, and kidneys was recorded as above or below the iliac crests. The distance from the iliac crest to the top of the fetus or gestational sac was determined. The CT images of the limited and full scanning studies were independently reviewed by two blinded radiologists to identify traumatic injuries. Fetal dose profiles, including both scatter and primary radiation, were computed analytically along the central axis of the patient to estimate fetal dose reduction. Linear regression analysis was performed between gestational age and distance of the fetus to the iliac crests. Thirty-five patients were included (mean age, 26.2 years). Gestational age ranged from 5 to 38 weeks, with 5, 19, and 11 gestations in the first, second, and third trimesters, respectively. All solid organs were above the iliac crests in all patients. In three of six patients, traumatic findings in the pelvis would have been missed with the limited study. There was high correlation between gestational age and distance of the fetus to the iliac crests (R(2) = 0.84). The mean gestational age at which the top of the fetus was at the iliac crest was 17.3 weeks. Using the limited scanning study, fetuses at 5, 20, and 40 weeks of gestation would receive an estimated 4.3%, 26.2%, and 59.9% of the dose, respectively, compared with the dose for the full scanning study. In pregnant patients in our series with a history of trauma, CT of the abdomen only was an effective technique to reduce fetal radiation exposure compared with full abdomen and pelvis CT.

WE-AB-BRA-11: Improved Imaging of Permanent Prostate Brachytherapy Seed Implants by Combining an Endorectal X-Ray Sensor with a CT Scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steiner, J; Matthews, K; Jia, G

Purpose: To test feasibility of the use of a digital endorectal x-ray sensor for improved image resolution of permanent brachytherapy seed implants compared to conventional CT. Methods: Two phantoms simulating the male pelvic region were used to test the capabilities of a digital endorectal x-ray sensor for imaging permanent brachytherapy seed implants. Phantom 1 was constructed from acrylic plastic with cavities milled in the locations of the prostate and the rectum. The prostate cavity was filled a Styrofoam plug implanted with 10 training seeds. Phantom 2 was constructed from tissue-equivalent gelatins and contained a prostate phantom implanted with 18 strandsmore » of training seeds. For both phantoms, an intraoral digital dental x-ray sensor was placed in the rectum within 2 cm of the seed implants. Scout scans were taken of the phantoms over a limited arc angle using a CT scanner (80 kV, 120–200 mA). The dental sensor was removed from the phantoms and normal helical CT and scout (0 degree) scans using typical parameters for pelvic CT (120 kV, auto-mA) were collected. A shift-and add tomosynthesis algorithm was developed to localize seed plane location normal to detector face. Results: The endorectal sensor produced images with improved resolution compared to CT scans. Seed clusters and individual seed geometry were more discernable using the endorectal sensor. Seed 3D locations, including seeds that were not located in every projection image, were discernable using the shift and add algorithm. Conclusion: This work shows that digital endorectal x-ray sensors are a feasible method for improving imaging of permanent brachytherapy seed implants. Future work will consist of optimizing the tomosynthesis technique to produce higher resolution, lower dose images of 1) permanent brachytherapy seed implants for post-implant dosimetry and 2) fine anatomic details for imaging and managing prostatic disease compared to CT images. Funding: LSU Faculty Start-up Funding. Disclosure: XDR Radiography has loaned our research group the digital x-ray detector used in this work. CoI: None.« less

Dual-Energy Micro-CT Functional Imaging of Primary Lung Cancer in Mice Using Gold and Iodine Nanoparticle Contrast Agents: A Validation Study

PubMed Central

Ashton, Jeffrey R.; Clark, Darin P.; Moding, Everett J.; Ghaghada, Ketan; Kirsch, David G.; West, Jennifer L.; Badea, Cristian T.

2014-01-01

Purpose To provide additional functional information for tumor characterization, we investigated the use of dual-energy computed tomography for imaging murine lung tumors. Tumor blood volume and vascular permeability were quantified using gold and iodine nanoparticles. This approach was compared with a single contrast agent/single-energy CT method. Ex vivo validation studies were performed to demonstrate the accuracy of in vivo contrast agent quantification by CT. Methods Primary lung tumors were generated in LSL-KrasG12D; p53FL/FL mice. Gold nanoparticles were injected, followed by iodine nanoparticles two days later. The gold accumulated in tumors, while the iodine provided intravascular contrast. Three dual-energy CT scans were performed–two for the single contrast agent method and one for the dual contrast agent method. Gold and iodine concentrations in each scan were calculated using a dual-energy decomposition. For each method, the tumor fractional blood volume was calculated based on iodine concentration, and tumor vascular permeability was estimated based on accumulated gold concentration. For validation, the CT-derived measurements were compared with histology and inductively-coupled plasma optical emission spectroscopy measurements of gold concentrations in tissues. Results Dual-energy CT enabled in vivo separation of gold and iodine contrast agents and showed uptake of gold nanoparticles in the spleen, liver, and tumors. The tumor fractional blood volume measurements determined from the two imaging methods were in agreement, and a high correlation (R2 = 0.81) was found between measured fractional blood volume and histology-derived microvascular density. Vascular permeability measurements obtained from the two imaging methods agreed well with ex vivo measurements. Conclusions Dual-energy CT using two types of nanoparticles is equivalent to the single nanoparticle method, but allows for measurement of fractional blood volume and permeability with a single scan. As confirmed by ex vivo methods, CT-derived nanoparticle concentrations are accurate. This method could play an important role in lung tumor characterization by CT. PMID:24520351

Neural network and its application to CT imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikravesh, M.; Kovscek, A.R.; Patzek, T.W.

We present an integrated approach to imaging the progress of air displacement by spontaneous imbibition of oil into sandstone. We combine Computerized Tomography (CT) scanning and neural network image processing. The main aspects of our approach are (I) visualization of the distribution of oil and air saturation by CT, (II) interpretation of CT scans using neural networks, and (III) reconstruction of 3-D images of oil saturation from the CT scans with a neural network model. Excellent agreement between the actual images and the neural network predictions is found.

Lung PET scan

MedlinePlus

... PET - chest; PET - lung; PET - tumor imaging; PET/CT - lung; Solitary pulmonary nodule - PET ... minutes. PET scans are performed along with a CT scan. This is because the combined information from ...

Rationale and Application of Tangential Scanning to Industrial Inspection of Hardwood Logs

Treesearch

Nand K. Gupta; Daniel L. Schmoldt; Bruce Isaacson

1998-01-01

Industrial computed tomography (CT) inspection of hardwood logs has some unique requirements not found in other CT applications. Sawmill operations demand that large volumes of wood be scanned quickly at high spatial resolution for extended duty cycles. Current CT scanning geometries and commercial systems have both technical and economic [imitations. Tangential...

Malignant external otitis: early scintigraphic detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strashun, A.M.; Nejatheim, M.; Goldsmith, S.J.

1984-02-01

Pseudomonas otitis externa in elderly diabetics may extend aggressively to adjacent bone, cranial nerves, meninges, and vessels, leading to a clinical diagnosis of ''malignant'' external otitis. Early diagnosis is necessary for successful treatment. This study compares the findings of initial radiographs, thin-section tomography of temporal bone, CT scans of head and neck, technetium-99m methylene diphosphonate (MDP) and gallium-67 citrate scintigraphy, and single-photon emission computed tomography (SPECT) for detection of temporal bone osteomylitis in ten patients fulfilling the clinical diagnostic criteria of malignant external otitis. Skull radiographs were negative in all of the eight patients studied. Thin-section tomography was positive inmore » one of the seven patients studied using this modality. CT scanning suggested osteomyelitis in three of nine patients. Both Tc-99m and Ga-67 citrate scintigraphy were positive in 10 of 10 patients. These results suggest that technetium and gallium scintigraphy are more sensitive than radiographs and CT scans for early detection of malignant external otitis.« less

The salutary effect of an integrated system on the rate of repeat CT scanning in transferred trauma patients: Improved costs and efficiencies.

PubMed

Bledsoe, Joseph; Liepert, Amy E; Allen, Todd L; Dong, Li; Hemingway, Jamon; Majercik, Sarah; Gardner, Scott; Stevens, Mark H

2017-08-01

Duplication of Computed Tomography (CT) scanning in trauma patients has been a source of quality waste in healthcare and potential harm for patients. Integrated and regional health systems have been shown to promote opportunities for efficiencies, cost savings and increased safety. This study evaluated traumatically injured patients who required transfer to a Level One Trauma Center (TC) from either within a vertically integrated healthcare system (IN) or from an out-of-network (OON) hospital. We found the rate of repeat CT scanning, radiology costs and total costs for day one of hospitalization to be significantly lower for trauma patients transferred from an IN hospital as compared to those patients transferred from OON hospitals. The inefficiencies and waste often associated with transferred patients can be mitigated and strategies to do so are necessary to reduce costs in the current healthcare environment. Copyright © 2017 Elsevier Inc. All rights reserved.

Beam hardening correction for interior tomography based on exponential formed model and radon inversion transform

NASA Astrophysics Data System (ADS)

Chen, Siyu; Zhang, Hanming; Li, Lei; Xi, Xiaoqi; Han, Yu; Yan, Bin

2016-10-01

X-ray computed tomography (CT) has been extensively applied in industrial non-destructive testing (NDT). However, in practical applications, the X-ray beam polychromaticity often results in beam hardening problems for image reconstruction. The beam hardening artifacts, which manifested as cupping, streaks and flares, not only debase the image quality, but also disturb the subsequent analyses. Unfortunately, conventional CT scanning requires that the scanned object is completely covered by the field of view (FOV), the state-of-art beam hardening correction methods only consider the ideal scanning configuration, and often suffer problems for interior tomography due to the projection truncation. Aiming at this problem, this paper proposed a beam hardening correction method based on radon inversion transform for interior tomography. Experimental results show that, compared to the conventional correction algorithms, the proposed approach has achieved excellent performance in both beam hardening artifacts reduction and truncation artifacts suppression. Therefore, the presented method has vitally theoretic and practicable meaning in artifacts correction of industrial CT.

Performance analysis of model based iterative reconstruction with dictionary learning in transportation security CT

NASA Astrophysics Data System (ADS)

Haneda, Eri; Luo, Jiajia; Can, Ali; Ramani, Sathish; Fu, Lin; De Man, Bruno

2016-05-01

In this study, we implement and compare model based iterative reconstruction (MBIR) with dictionary learning (DL) over MBIR with pairwise pixel-difference regularization, in the context of transportation security. DL is a technique of sparse signal representation using an over complete dictionary which has provided promising results in image processing applications including denoising,1 as well as medical CT reconstruction.2 It has been previously reported that DL produces promising results in terms of noise reduction and preservation of structural details, especially for low dose and few-view CT acquisitions.2 A distinguishing feature of transportation security CT is that scanned baggage may contain items with a wide range of material densities. While medical CT typically scans soft tissues, blood with and without contrast agents, and bones, luggage typically contains more high density materials (i.e. metals and glass), which can produce severe distortions such as metal streaking artifacts. Important factors of security CT are the emphasis on image quality such as resolution, contrast, noise level, and CT number accuracy for target detection. While MBIR has shown exemplary performance in the trade-off of noise reduction and resolution preservation, we demonstrate that DL may further improve this trade-off. In this study, we used the KSVD-based DL3 combined with the MBIR cost-minimization framework and compared results to Filtered Back Projection (FBP) and MBIR with pairwise pixel-difference regularization. We performed a parameter analysis to show the image quality impact of each parameter. We also investigated few-view CT acquisitions where DL can show an additional advantage relative to pairwise pixel difference regularization.

Postoperative PET/CT and target delineation before adjuvant radiotherapy in patients with oral cavity squamous cell carcinoma.

PubMed

Dutta, Pinaki R; Riaz, Nadeem; McBride, Sean; Morris, Luc G; Patel, Snehal; Ganly, Ian; Wong, Richard J; Palmer, Frank; Schöder, Heiko; Lee, Nancy

2016-04-01

The purpose of this study was for us to present our evaluation of the effectiveness of positron emission tomography (PET)/CT imaging in postoperative patients with oral cavity squamous cell carcinoma (SCC) before initiating adjuvant radiation therapy. Treatment planning PET/CT scans were obtained in 44 patients with oral cavity SCC receiving adjuvant radiation. We identified target areas harboring macroscopic disease requiring higher radiation doses or additional surgery. Fourteen PET/CT scans were abnormal. Thirteen patients underwent surgery and/or biopsy, increased radiation dose, and/or addition of chemotherapy. Eleven patients received higher radiation doses. Patients undergoing imaging >8 weeks were more likely to have abnormal results (p = .01). One-year distant metastases-free survival was significantly worse in patients with positive PET/CT scans (61.5% vs 92.7%; p = .01). The estimated positive predictive value (PPV) was 38% for postoperative PET/CT scanning. We demonstrated that 32% of patients have abnormal PET/CT scans resulting in management changes. Patients may benefit from postoperative PET/CT imaging to optimize adjuvant radiation treatment planning. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1285-E1293, 2016. © 2015 Wiley Periodicals, Inc.

Thirteen-Year Evaluation of Highly Cross-Linked Polyethylene Articulating With Either 28-mm or 36-mm Femoral Heads Using Radiostereometric Analysis and Computerized Tomography.

PubMed

Nebergall, Audrey K; Greene, Meridith E; Rubash, Harry; Malchau, Henrik; Troelsen, Anders; Rolfson, Ola

2016-09-01

The objective of this 13-year prospective evaluation of highly cross-linked ultra high molecular weight polyethylene (HXLPE) was to (1) assess the long-term wear of HXLPE articulating with 2 femoral head sizes using radiostereometric analysis (RSA) and to (2) determine if osteolysis is a concern with this material through the use of plain radiographs and computerized tomography (CT). All patients received a Longevity HXLPE liner with tantalum beads and either a 28-mm or 36-mm femoral head. Twelve patients (6 in each head size group) agreed to return for 13-year RSA, plain radiograph, and CT follow-up. The 1-year and 13-year plain radiographs as well as the CT scans were analyzed for the presence of osteolysis. The 13-year mean ± standard error steady-state wear was 0.05 ± 0.02 mm with no significant increase over time or between the 2 head size groups. Two patients' CT scans showed radiolucent regions in the acetabulum of 4.51 cm(3) and 11.25 cm(3), respectively. In one patient, this area corresponded to a partially healed degenerative cyst treated with autograft during surgery. The second patient had an acetabular protrusio treated with autograft, and the CT scan revealed areas of remodeling of this graft. One patient's 13-year plain radiographs showed evidence of cup loosening and linear radiolucencies in zones 2 and 3. There was no evidence of significant wear over time using RSA. The CT scans did not show evidence of osteolysis due to wear particles. These results suggest that this material has reduced wear compared to conventional polyethylene, irrespective of head size. Copyright © 2016 Elsevier Inc. All rights reserved.

The relationship of body mass index and abdominal fat on the radiation dose received during routine computed tomographic imaging of the abdomen and pelvis.

PubMed

Chan, Victoria O; McDermott, Shaunagh; Buckley, Orla; Allen, Sonya; Casey, Michael; O'Laoide, Risteard; Torreggiani, William C

2012-11-01

To determine the relationship of increasing body mass index (BMI) and abdominal fat on the effective dose acquired from computed tomography (CT) abdomen and pelvis scans. Over 6 months, dose-length product and total milliamp-seconds (mAs) from routine CT abdomen and pelvis scans of 100 patients were recorded. The scans were performed on a 64-slice CT scanner by using an automatic exposure control system. Effective dose (mSv) based on dose-length product, BMI, periumbilical fat thickness, and intra-abdominal fat were documented for each patient. BMI, periumbilical fat thickness, and intra-abdominal fat were compared with effective dose. Thirty-nine men and 61 women were included in the study (mean age, 56.3 years). The mean BMI was 26.2 kg/m(2). The mean effective dose was 10.3 mSv. The mean periumbilical fat thickness was 2.4 cm. Sixty-five patients had a small amount of intra-abdominal fat, and 35 had a large amount of intra-abdominal fat. The effective dose increased with increasing BMI (P < .001) and increasing amounts of intra-abdominal fat (P < .001). For every kilogram of weight, there is a 0.13 mSv increase in effective dose, which is equal to 6.5 chest radiographs per CT examination. For an increase in BMI by 5 kg/m(2), there is a 1.95 mSv increase in effective dose, which is equal to 97.5 chest radiographs per CT examination. Increasing BMI and abdominal fat significantly increases the effective dose received from CT abdomen and pelvis scans. Copyright © 2012 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

Weight bearing cone beam CT scan versus gravity stress radiography for analysis of supination external rotation injuries of the ankle.

PubMed

Marzo, John M; Kluczynski, Melissa A; Clyde, Corey; Anders, Mark J; Mutty, Christopher E; Ritter, Christopher A

2017-12-01

For AO 44-B2 ankle fractures of uncertain stability, the current diagnostic standard is to obtain a gravity stress radiograph, but some have advocated for the use of weight-bearing radiographs. The primary aim was to compare measures of medial clear space (MCS) on weight-bearing cone beam computed tomography (CBCT) scans versus gravity stress radiographs for determining the state of stability of ankle fractures classified as AO SER 44-B2 or Weber B. The secondary aim was to evaluate the details offered by CBCT scans with respect to other findings that may be relevant to patient care. Nine patients were enrolled in this cross-sectional study between April 2016 and February 2017 if they had an AO SER 44-B2 fracture of uncertain stability, had a gravity stress radiograph, and were able to undergo CT scan within seven days. The width of the MCS was measured at the level of the talar dome on all radiographs and at the mid coronal slice on CT. Wilcoxon signed-ranks tests were used to compare MCS between initial radiographs, gravity stress radiographs and weight-bearing CBCT scans. MCS on weight-bearing CBCT scan (1.41±0.41 mm) was significantly less than standard radiographs (3.28±1.63 mm, P=0.004) and gravity stress radiographs (5.82±1.93 mm, P=0.02). There was no statistically significant difference in MCS measured on standard radiographs versus gravity stress radiographs (P=0.11). Detailed review of the multiplanar CT images revealed less than perfect anatomical reduction of the fractures, with residual fibular shortening, posterior displacement, and fracture fragments in the incisura as typical findings. Similar to weight-bearing radiographs, weight-bearing CBCT scan can predict stability of AO 44-B2 ankle fractures by showing restoration of the MCS, and might be used to indicate patients for non-operative treatment. None of the fractures imaged in this study were perfectly reduced however, and further clinical research is necessary to determine if any of the detailed weight-bearing CBCT findings are related to patient outcomes.

Management of minor head injury in patients receiving oral anticoagulant therapy: a prospective study of a 24-hour observation protocol.

PubMed

Menditto, Vincenzo G; Lucci, Moira; Polonara, Stefano; Pomponio, Giovanni; Gabrielli, Armando

2012-06-01

Patients receiving warfarin who experience minor head injury are at risk of intracranial hemorrhage, and optimal management after a single head computed tomography (CT) scan is unclear. We evaluate a protocol of 24-hour observation followed by a second head CT scan. In this prospective case series, we enrolled consecutive patients receiving warfarin and showing no intracranial lesions on a first CT scan after minor head injury treated at a Level II trauma center. We implemented a structured clinical pathway, including 24-hour observation and a CT scan performed before discharge. We then evaluated the frequency of death, admission, neurosurgery, and delayed intracranial hemorrhage. We enrolled and observed 97 consecutive patients. Ten refused the second CT scan and were well during 30-day follow-up. Repeated CT scanning in the remaining 87 patients revealed a new hemorrhage lesion in 5 (6%), with 3 subsequently hospitalized and 1 receiving craniotomy. Two patients discharged after completing the study protocol with 2 negative CT scan results were admitted 2 and 8 days later with symptomatic subdural hematomas; neither received surgery. Two of the 5 patients with delayed bleeding at 24 hours had an initial international normalized ratio greater than 3.0, as did both patients with delayed bleeding beyond 24 hours. The relative risk of delayed hemorrhage with an initial international normalized ratio greater than 3.0 was 14 (95% confidence interval 4 to 49). For patients receiving warfarin who experience minor head injury and have a negative initial head CT scan result, a protocol of 24-hour observation followed by a second CT scan will identify most occurrences of delayed bleeding. An initial international normalized ratio greater than 3 suggests higher risk. Copyright © 2011 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

Predictors of positive 18F-FDG PET/CT-scan for large vessel vasculitis in patients with persistent polymyalgia rheumatica.

PubMed

Prieto-Peña, Diana; Martínez-Rodríguez, Isabel; Loricera, Javier; Banzo, Ignacio; Calderón-Goercke, Mónica; Calvo-Río, Vanesa; González-Vela, Carmen; Corrales, Alfonso; Castañeda, Santos; Blanco, Ricardo; Hernández, José L; González-Gay, Miguel Á

2018-05-18

Polymyalgia rheumatica (PMR) is often the presenting manifestation of giant cell arteritis (GCA). Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan often discloses the presence of large vessel vasculitis (LVV) in PMR patients. We aimed to identify predictive factors of a positive PET/CT scan for LVV in patients classified as having isolated PMR according to well-established criteria. A set of consecutive patients with PMR from a single hospital were assessed. All of them underwent PET/CT scan between January 2010 and February 2018 based on clinical considerations. Patients with PMR associated to other diseases, including those with cranial features of GCA, were excluded. The remaining patients were categorized in classic PMR (if fulfilled the 2012 EULAR/ACR classification criteria at disease diagnosis; n = 84) or atypical PMR (who did not fulfill these criteria; n = 16). Only information on patients with classic PMR was assessed. The mean age of the 84 patients (51 women) with classic PMR was 71.4 ± 9.2 years. A PET/CT scan was positive in 51 (60.7%). Persistence of classic PMR symptoms was the most common reason to perform a PET/CT scan. Nevertheless, patients with positive PET/CT scan often had unusual symptoms. The best set of predictors of a positive PET/CT scan were bilateral diffuse lower limb pain (OR = 8.8, 95% CI: 1.7-46.3; p = 0.01), pelvic girdle pain (OR = 4.9, 95% CI: 1.50-16.53; p = 0.01) and inflammatory low back pain (OR = 4.7, 95% CI: 1.03-21.5; p = 0.04). Inflammatory low back pain, pelvic girdle and diffuse lower limb pain are predictors of positive PET/CT scan for LVV in PMR. Copyright © 2018 Elsevier Inc. All rights reserved.

The Detection of Focal Liver Lesions Using Abdominal CT: A Comparison of Image Quality Between Adaptive Statistical Iterative Reconstruction V and Adaptive Statistical Iterative Reconstruction.

PubMed

Lee, Sangyun; Kwon, Heejin; Cho, Jihan

2016-12-01

To investigate image quality characteristics of abdominal computed tomography (CT) scans reconstructed with adaptive statistical iterative reconstruction V (ASIR-V) vs currently using applied adaptive statistical iterative reconstruction (ASIR). This institutional review board-approved study included 35 consecutive patients who underwent CT of the abdomen. Among these 35 patients, 27 with focal liver lesions underwent abdomen CT with a 128-slice multidetector unit using the following parameters: fixed noise index of 30, 1.25 mm slice thickness, 120 kVp, and a gantry rotation time of 0.5 seconds. CT images were analyzed depending on the method of reconstruction: ASIR (30%, 50%, and 70%) vs ASIR-V (30%, 50%, and 70%). Three radiologists independently assessed randomized images in a blinded manner. Imaging sets were compared to focal lesion detection numbers, overall image quality, and objective noise with a paired sample t test. Interobserver agreement was assessed with the intraclass correlation coefficient. The detection of small focal liver lesions (<10 mm) was significantly higher when ASIR-V was used when compared to ASIR (P <0.001). Subjective image noise, artifact, and objective image noise in liver were generally significantly better for ASIR-V compared to ASIR, especially in 50% ASIR-V. Image sharpness and diagnostic acceptability were significantly worse in 70% ASIR-V compared to various levels of ASIR. Images analyzed using 50% ASIR-V were significantly better than three different series of ASIR or other ASIR-V conditions at providing diagnostically acceptable CT scans without compromising image quality and in the detection of focal liver lesions. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Investigation of Energy-Dispersive X-ray Computed Tomography System with CdTe Scan Detector and Comparing-Differentiator and Its Application to Gadolinium K-Edge Imaging

NASA Astrophysics Data System (ADS)

Chiba, Hiraku; Sato, Yuichi; Sato, Eiichi; Maeda, Tomoko; Matsushita, Ryo; Yanbe, Yutaka; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2012-10-01

An energy-dispersive (ED) X-ray computed tomography (CT) system is useful for carrying out monochromatic imaging by selecting optimal energy photons. CT is performed by repeated linear scans and rotations of an object. X-ray photons from the object are detected by the cadmium telluride (CdTe) detector, and event pulses of X-ray photons are produced using charge-sensitive and shaping amplifiers. The lower photon energy is determined by a comparator, and the maximum photon energy of 70 keV corresponds to the tube voltage. Logical pulses from the comparator are counted by a counter card through a differentiator to reduce pulse width and rise time. In the ED-CT system, tube voltage and current were 70 kV and 0.30 mA, respectively, and X-ray intensity was 18.2 µGy/s at 1.0 m from the source at a tube voltage of 70 kV. Demonstration of gadolinium K-edge CT for cancer diagnosis was carried out by selecting photons with energies ranging from 50.4 to 70 keV, and photon-count energy subtraction imaging from 30 to 50.3 keV was also performed.

Estimating the lifetime risk of cancer associated with multiple CT scans.

PubMed

Ivanov, V K; Kashcheev, V V; Chekin, S Yu; Menyaylo, A N; Pryakhin, E A; Tsyb, A F; Mettler, F A

2014-12-01

Multiple CT scans are often done on the same patient resulting in an increased risk of cancer. Prior publications have estimated risks on a population basis and often using an effective dose. Simply adding up the risks from single scans does not correctly account for the survival function. A methodology for estimating personal radiation risks attributed to multiple CT imaging using organ doses is presented in this article. The estimated magnitude of the attributable risk fraction for the possible development of radiation-induced cancer indicates the necessity for strong clinical justification when ordering multiple CT scans.

[Non-operation management of 12 cases with brain abscess demonstrated by CT scan].

PubMed

Long, J

1990-12-01

This paper reported 12 cases with brain abscess demonstrated by CT scan. Using antibiotic management without surgical intervention, in 10 cases the curative effects were satisfactory. The paper indicated that CT scan was very useful in prompt and correct diagnosis of brain abscess and with sequential CT scan medical therapy was feasible. It is significant in treatment of brain abscess especially for the patients who have a poor general condition, have the brain abscess located in important functional area or have multiple abscesses so that the operation is difficult for them.

Prognostic Value and Reproducibility of Pretreatment CT Texture Features in Stage III Non-Small Cell Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fried, David V.; Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas; Tucker, Susan L.

2014-11-15

Purpose: To determine whether pretreatment CT texture features can improve patient risk stratification beyond conventional prognostic factors (CPFs) in stage III non-small cell lung cancer (NSCLC). Methods and Materials: We retrospectively reviewed 91 cases with stage III NSCLC treated with definitive chemoradiation therapy. All patients underwent pretreatment diagnostic contrast enhanced computed tomography (CE-CT) followed by 4-dimensional CT (4D-CT) for treatment simulation. We used the average-CT and expiratory (T50-CT) images from the 4D-CT along with the CE-CT for texture extraction. Histogram, gradient, co-occurrence, gray tone difference, and filtration-based techniques were used for texture feature extraction. Penalized Cox regression implementing cross-validation wasmore » used for covariate selection and modeling. Models incorporating texture features from the 33 image types and CPFs were compared to those with models incorporating CPFs alone for overall survival (OS), local-regional control (LRC), and freedom from distant metastases (FFDM). Predictive Kaplan-Meier curves were generated using leave-one-out cross-validation. Patients were stratified based on whether their predicted outcome was above or below the median. Reproducibility of texture features was evaluated using test-retest scans from independent patients and quantified using concordance correlation coefficients (CCC). We compared models incorporating the reproducibility seen on test-retest scans to our original models and determined the classification reproducibility. Results: Models incorporating both texture features and CPFs demonstrated a significant improvement in risk stratification compared to models using CPFs alone for OS (P=.046), LRC (P=.01), and FFDM (P=.005). The average CCCs were 0.89, 0.91, and 0.67 for texture features extracted from the average-CT, T50-CT, and CE-CT, respectively. Incorporating reproducibility within our models yielded 80.4% (±3.7% SD), 78.3% (±4.0% SD), and 78.8% (±3.9% SD) classification reproducibility in terms of OS, LRC, and FFDM, respectively. Conclusions: Pretreatment tumor texture may provide prognostic information beyond that obtained from CPFs. Models incorporating feature reproducibility achieved classification rates of ∼80%. External validation would be required to establish texture as a prognostic factor.« less

Vomiting--is this a good indication for CT head scans in patients with minor head injury?

PubMed

Bainbridge, J; Khirwadkar, H; Hourihan, M D

2012-02-01

The National Institute for Health and Clinical Excellence head injury guidelines advise CT imaging within 1 h if there is more than one episode of vomiting post-head injury in adults and three or more episodes in children. Since the guideline publication, studies have found that, following head injury, vomiting alone is associated with an abnormal CT head scan in 13-45% of cases. CT head scan requests referred from the emergency department between 1 May 2009 and 30 April 2010 were retrospectively reviewed. Patients with vomiting as the sole indication for an "immediate" CT head scan performed within 1 h were included in the study. Reports produced by experienced neuroradiologists were reviewed and the detection of significant head injury was noted. There were 1264 CT head scans performed during our study period. 151 (124 adults, 27 children) were indicated owing to vomiting following head injury. 5 of the 124 adult scans and 1 of the 27 paediatric scans showed an abnormal finding, giving positive predictive values (PPV) of 4% and 3.7%, respectively. None of these patients required either acute or delayed neurosurgical intervention. In our experience, vomiting alone has a PPV of 4% for significant head injury in adults. However, none of these injuries were serious enough to warrant acute or delayed intervention. Given these findings, vomiting following head injury is a reasonable indication for a CT head scan; however, as none of the patients required acute intervention, we suggest that these scans do not usually need to be performed within 1 h of request.

Hybrid detection of lung nodules on CT scan images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Lin; Tan, Yongqiang; Schwartz, Lawrence H.

Purpose: The diversity of lung nodules poses difficulty for the current computer-aided diagnostic (CAD) schemes for lung nodule detection on computed tomography (CT) scan images, especially in large-scale CT screening studies. We proposed a novel CAD scheme based on a hybrid method to address the challenges of detection in diverse lung nodules. Methods: The hybrid method proposed in this paper integrates several existing and widely used algorithms in the field of nodule detection, including morphological operation, dot-enhancement based on Hessian matrix, fuzzy connectedness segmentation, local density maximum algorithm, geodesic distance map, and regression tree classification. All of the adopted algorithmsmore » were organized into tree structures with multi-nodes. Each node in the tree structure aimed to deal with one type of lung nodule. Results: The method has been evaluated on 294 CT scans from the Lung Image Database Consortium (LIDC) dataset. The CT scans were randomly divided into two independent subsets: a training set (196 scans) and a test set (98 scans). In total, the 294 CT scans contained 631 lung nodules, which were annotated by at least two radiologists participating in the LIDC project. The sensitivity and false positive per scan for the training set were 87% and 2.61%. The sensitivity and false positive per scan for the testing set were 85.2% and 3.13%. Conclusions: The proposed hybrid method yielded high performance on the evaluation dataset and exhibits advantages over existing CAD schemes. We believe that the present method would be useful for a wide variety of CT imaging protocols used in both routine diagnosis and screening studies.« less

18F-FDG SPECT/CT in the diagnosis of differentiated thyroid carcinoma with elevated thyroglobulin and negative iodine-131 scans.

PubMed

Ma, C; Wang, X; Shao, M; Zhao, L; Jiawei, X; Wu, Z; Wang, H

2015-06-01

Aim of the present study was to investigate the usefulness of 18F-FDG SPECT/CT in differentiated thyroid cancer (DTC) with elevated serum thyroglobulin (Tg) but negative iodine-131 scan. This retrospective review of patients with DTC recurrence who had 18F-FDG SPECT/CT and 18F-FDG PET/CT for elevated serum Tg but negative iodine-131 scan (March 2007-October 2012). After total thyroidectomy followed by radioiodine ablation, 86 consecutive patients with elevated Tg levels underwent 18F-FDG SPECT/CT or 18F-FDG PET/CT. Of these, 45 patients had 18F-FDG SPECT/CT, the other 41 patients had 18F-FDG PET/CT 3-4weeks after thyroid hormone withdrawal. The results of 18F-FDG PET/CT and SPECT/CT were correlated with patient follow-up information, which included the results from subsequent imaging modalities such as neck ultrasound, MRI and CT, Tg levels, and histologic examination of surgical specimens. The diagnostic accuracy of the two imaging modalities was evaluated. In 18F-FDG SPECT/CT scans, 24 (24/45) patients had positive findings, 22 true positive in 24 patients, false positive in 2 patients, true-negative and false-negative in 6, 15 patients, respectively. The overall sensitivity, specificity, and accuracy of 18F-FDG SPECT/CT were 59.5%, 75% and 62.2%, respectively. Twenty six patients had positive findings on 18F-FDG PET/CT scans, 23 true positive in 26 (26/41) patients, false positive in 3 patients, true-negative and false-negative in 9, 6 patients, respectively. The overall sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 79.3%, 81.8% and 78.1%, respectively. Clinical management changed for 13 (29%) of 45 patients by 18F-FDG SPECT/CT, 14 (34%) of 41 patients by 18F-FDG PET/CT including surgery, radiation therapy, or multikinase inhibitor. Based on the retrospective analysis of 86 patients, 18F-FDG SPECT/CT has lower sensitivity in the diagnosis of DTC recurrence with elevated Tg and negative iodine-131scan to 18F-FDG PET/CT. The clinical application of FDG SPECT/CT is then limited and cannot replace PET/CT.