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Sample records for 128-slice 4d-perfusion ct

  1. Estimation of Radiation Exposure of 128-Slice 4D-Perfusion CT for the Assessment of Tumor Vascularity

    PubMed Central

    Horger, Marius; Buchgeister, Markus; Fenchel, Michael; Thomas, Christoph; Boehringer, Nadine; Schulze, Maximilian; Tsiflikas, Ilias; Claussen, Claus D.; Heuschmid, Martin

    2010-01-01

    Objective We aimed to estimate the effective dose of 4D-Perfusion-CT protocols of the lung, liver, and pelvis for the assessment of tumor vascularity. Materials and Methods An Alderson-Rando phantom equipped with thermoluminescent dosimeters was used to determine the effective dose values of 4D-Perfusion-CT. Phantom measurements were performed on a 128-slice single-source scanner in adaptive 4D-spiral-mode with bidirectional table movement and a total scan range of 69 mm over a time period of nearly 120 seconds (26 scans). Perfusion measurements were simulated for the lung, liver, and pelvis under the following conditions: lung (80 kV, 60 mAs), liver (80 kV/80 mAs and 80 kV/120 mAs), pelvis (100 kV/80 mAs and 100 kV/120 mAs). Results Depending on gender, the evaluated body region and scan protocol, an effective whole-body dose between 2.9-12.2 mSv, was determined. The radiation exposure administered to gender-specific organs like the female breast tissue (lung perfusion) or to the ovaries (pelvic perfusion) led to an increase in the female specific dose by 86% and 100% in perfusion scans of the lung and the pelvis, respectively. Conclusion Due to a significant radiation dose of 4D-perfusion-CT protocols, the responsible use of this new promising technique is mandatory. Gender- and organ-specific differences should be considered for indication and planning of tumor perfusion scans. PMID:20808699

  2. Assessments of Coronary Artery Visibility and Radiation Dose in Infants with Congenital Heart Disease on Cardiac 128-slice CT and on Cardiac 64-slice CT.

    PubMed

    Cui, Y; Huang, M; Zheng, J; Li, J; Liu, H; Liang, C

    2016-01-01

    The aim of this study was to compare the coronary artery visibility and radiation dose in infants with CHD on cardiac 128-slice CT and on cardiac 64-slice CT. The images of 200 patients were analyzed in this study, 100 patients were selected randomly from a group of 789 infants (<1 years old) with CHD undergoing 128-slice CT prospective ECG-triggered axial scan, and 100 were selected randomly from 911 infants with CHD undergoing 64-slice CT retrospective ECG-gated spiral scan. The visibility of coronary artery segments was graded on a four-point scale. The coronary arteries were considered to be detected or visible when grade was 2 or higher. The visibility of the coronary artery segments and the radiation dose was compared between the two groups. Except for the rate of LM (96 vs. 99%), the detection rates of the total, LAD, LCX, RCA, and the proximal segment of the RCA in the 256-slice CT group were significantly higher than those in the 64-slice CT group (51.7, 53.33, 33.67, 53.33, and 99 vs. 34.8, 34.33, 18, 30.67, and 75%, respectively). The counts of visibility score (4/3/2/1) for the LM and the proximal segment of the RCA were 62/22/12/4 and 56/20/17/7, respectively, in the 128-slice CT group and 17/42/30/1 and 9/30/38/25, respectively, in the 64-slice CT group. There were significant differences, especially for score 4 and 3, between the two groups. The radiation dose in the 128-slice CT group was significantly decreased than those in the 64-slice CT group (CTDIvol 1.88 ± 0.51 vs. 5.61 ± 0.63 mGy; SSDE 4.48 ± 1.15 vs. 13.97 ± 1.52 mGy; effective radiation dose 1.36 ± 0.44 vs. 4.06 ± 0.7 mSv). With reduced radiation dose, the visibility of the coronary artery in infants with CHD via prospective ECG-triggered mode on a 128-slice CT is superior to that of the 64-slice CT using retrospective ECG-gated spiral mode. PMID:26271472

  3. Application of Prospective ECG-Gated High-Pitch 128-Slice Dual-Source CT Angiography in the Diagnosis of Congenital Extracardiac Vascular Anomalies in Infants and Children

    PubMed Central

    Wang, Ximing; Duan, Yanhua; Xu, Wenjian; Li, Haiou; Cao, Ting; Liu, Xuejun; Ji, Xiaopeng; Cheng, Zhaoping; Wang, Anbiao

    2014-01-01

    Purpose To investigate the value of prospective ECG-gated high-pitch 128-slice dual-source CT (DSCT) angiography in the diagnosis of congenital extracardiac vascular anomalies in infants and children in comparison with transthoracic echocardiography (TTE). Methods Eighty consecutive infants or children clinically diagnosed of congenital heart disease and suspected with extracardiac vascular anomaly were enrolled, and 75 patients were finally included in this prospective study. All patients underwent prospective ECG-gated high-pitch DSCT angiography after TTE with an interval of 1–7 days. The diagnostic accuracy and sensitivity of high-pitch DSCT angiography and TTE were compared according to the surgical/CCA findings. The image quality of DSCT was assessed using a five-point scale. The effective radiation dose (ED) was calculated. Results A total of 17 congenital heart diseases and 162 separate extracardiac vascular anomalies were confirmed by surgical/CCA findings in 75 patients. The diagnostic accuracy of high-pitch DSCT angiography and TTE was 99.67% and 97.89%, respectively. The sensitivity of high-pitch DSCT angiography and TTE was 97.53% and 79.62%, respectively. There was significant difference regarding to the diagnostic accuracy and the sensitivity between high-pitch DSCT angiography and TTE (χ2 = 23.561 and 28.013, P<0.05). The agreement on the image quality scoring of DSCT between the two observers was excellent (κ = 0.81), and the mean score of image quality was 4.1±0.7. The mean ED of DSCT was 0.29±0.08 mSv. Conclusions Prospective ECG-gated high-pitch 128-slice DSCT angiography with low radiation dose and high diagnostic accuracy has higher sensitivity compared to TTE in the detection of congenital extracardiac vascular anomalies in infants and children. PMID:25546178

  4. Evaluation of high-pitch flash scan for pulmonary venous CTA on a 128-slice dual source CT: compared with prospective ECG-triggered sequence scan.

    PubMed

    Cao, Li Xiu; Zhang, Huan; Liu, Bo; Yang, Wen Jie; Zhang, Yan Yan; Pan, Zi Lai; Yan, Fu Hua; Chen, Ke Min

    2013-10-01

    To compare the image quality (IQ) and radiation dose of high-pitch scan and prospective ECG-triggered sequence scan on a 128-slice DSCT system for patients with atrial fibrillation (AF). Pulmonary venous (PV) CTA was performed with two protocols, including high-pitch scan and prospective ECG-triggered sequence scan. For each protocol, 20 sex, age and body-mass-index (mean 24.2 kg/m(2)) matched patients were identified. Two experienced radiologists, who were blinded to the scan protocols, independently graded the CT images of the two groups by a 5-point scale for subjective IQ assessment. Measured CT attenuation (Hounsfield units ± standard deviation), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) at various anatomic locations were also recorded for objective IQ evaluation. Radiation exposure parameters [dose length product (DLP) and effective radiation dose (ERD)] were compared. Twenty-three patients (57.5 %) showed an ECG pattern of AF in total. Subjective IQ was rated excellent in 100 % for the high-pitch scan group, while minor step artifacts were observed in two patients (10 %) with arrhythmia for the prospective ECG-triggered sequence group. There was no significant difference on IQ, neither by subjective, nor by objective measures (SNR, CNR) between the two groups. The ERD of high-pitch flash scan and prospective ECG-triggered sequence scan were 0.9 (± 0.25) and 2.9 (± 0.69) mSv, respectively. Significantly lower radiation was achieved by using high-pitch flash scan (P < 0.05). High-pitch flash scan can provide similar subjective and objective IQ compared with prospective ECG-triggered sequence scan for PV CTA, while radiation exposure was significantly reduced. PMID:23645131

  5. Mid-Term Patency in Radial Artery and Saphenous Vein After Coronary Artery Bypass Grafting in Asymptomatic Patients Using 128-Slice CT Coronary Angiography

    PubMed Central

    Sadeghpour, Ali; Pouraliakbar, Hamidreza; Azarfarin, Rasoul; Alizadeh Ghavidel, Alireza; Zavareian, Somayeh; Amirahmadi, Ali

    2015-01-01

    Background: Patency of the revascularization conduit is an essential predictor of long-standing survival after coronary artery bypass grafting. Objectives: We have conducted this study to compare the mid-term patency rates of radial artery (RA), left internal thoracic artery (LITA) and also saphenous vein (SV) grafts in asymptomatic patients following coronary artery bypass graft surgery (CABG) undergoing total IV anesthesia. Patients and Methods: In this study, 30 three-vessel disease patients with 104 RA, LITA, and SV grafts used concomitantly for primary isolated non-emergent CABG surgery were assessed. The primary end point was CT angiographic graft patency rate. After 53.5 (24-97) months’ follow-up, graft patency was assessed using 128-slice CT coronary angiography. Logistic regression analysis was used to detect the independent predictors of graft failure. Results: A total of 104 grafts, including 30 LITA, 44 SV, and 30 RA grafts, were studied. Cumulative graft patency rates were 93.3% in LITA, 83.3% in RA, and 70.5% in SV grafts. Statistically significant difference was found between the LITA and the SV graft patency rates (P = 0.019), whereas the difference between the RA conduit patency and the LITA or SV graft patency rates did not have any statistical significance (P = 0.424 and P = 0.273, respectively). Independent predictors of RA grafts occlusion were native coronary stenosis < 70% and female gender. Conclusions: In our patients, the RA grafts had an acceptable patency rate in 2 to 5 years’ follow-up. Although the SV grafts had a relatively higher patency rate than RA grafts in our asymptomatic patients, the patency rates in RA and SV grafts were close to each other. The RA graft function was poor in the patients with a higher number of risk factors and in the females. PMID:25789243

  6. Evaluation of a Chest Circumference-Adapted Protocol for Low-Dose 128-Slice Coronary CT Angiography with Prospective Electrocardiogram Triggering

    PubMed Central

    Lu, Chenying; Wang, Zufei; Wang, Hailin; Hu, Xianghua; Chen, Chunmiao

    2015-01-01

    Objective To assess the effect of chest circumference-adapted scanning protocol on radiation exposure and image quality in patients undergoing prospective electrocardiogram (ECG)-triggered coronary CT angiography (CCTA). Materials and Methods One hundred-eighty-five consecutive patients, who had undergone prospective ECG triggering CCTA with a 128-slice CT, were included in the present study. Nipple-level chest circumference, body weight and height were measured before CT examinations. Patients were divided into four groups based on kV/ref·mAs = 100/200, 100/250, 120/200, and 120/250, when patient's chest circumference was ≤ 85.0 (n = 56), 85.0-90.0 (n = 53), 90.0-95.0 (n = 44), and > 95.0 (n = 32), respectively. Image quality per-segment was independently assessed by two experienced observers. Image noise and attenuation were also measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The effective radiation dose was calculated using CT dose volume index and the dose-length product. Results A significant correlation was observed between patients' chest circumference and body mass index (r = 0.762, p < 0.001). Chest circumference ranged from 74 to 105 cm, and the mean effective radiation dose was 1.9-3.8 mSv. Diagnostic image quality was obtained in 98.5% (2440/2478) of all evaluated coronary segments without any significant differences among the four groups (p = 0.650). No significant difference in image noise was observed among the four groups (p = 0.439), thus supporting the validity of the chest circumference-adapted scanning protocol. However, vessel attenuation, SNR and CNR were significantly higher in the 100 kV groups than in the 120 kV groups (p < 0.05). Conclusion A measure of chest circumference can be used to adapt tube voltage and current for individualized radiation dose control, with resultant similar image noise and sustained diagnostic image quality. PMID:25598671

  7. Low-dose coronary-CT angiography using step and shoot at any heart rate: comparison of image quality at systole for high heart rate and diastole for low heart rate with a 128-slice dual-source machine.

    PubMed

    Paul, Jean-François; Amato, Aude; Rohnean, Adela

    2013-03-01

    To compare image quality of coronary CT angiography in step-and-shoot mode at the diastolic phase at low heart rates (<70 bpm) and systolic phase at high heart rates (≥70 bpm). We prospectively included 96 consecutive patients then excluded 5 patients with arrhythmia. Coronary CT-angiography was performed using a dual-source 128-slice CT machine, at the diastolic phase in the 55 patients with heart rates <70 bpm (group D) and at the systolic phase in the 36 patients with heart rates ≥70 (group S). Image quality was scored on a 5 point-scale (1, not interpretable; 2, insufficient for diagnosis; 3, fair, sufficient for diagnosis; 4, good; 5, excellent). In addition, we compared the number of stair-step artifacts in the two groups. Mean image quality score was 4 (0.78) in group D and 4.1 (0.34) in group S (NS), with an unequal distribution (p = 0.01). Step artifacts were seen in 44 % of group D and 18 % of group S patients (p = 0.02). In 3 group D patients and no group S patients, the image score was <3 due to artifacts, requiring repeat CT-angiography. When performing dual-source 128-slice CT-angiography, step-and-shoot acquisition provides comparable mean image quality in systole, with less variability and fewer stair-step artifacts, compared to diastole. This method may be feasible at any heart rate in most patients in sinus rhythm, allowing low-dose prospective acquisition without beta-blocker premedication. PMID:22918571

  8. 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

  9. Comparison of enhancement and image quality: different iodine concentrations for liver on 128-slice multidetector computed tomography in the same chronic liver disease patients

    PubMed Central

    Jo, Byoung Goo; Song, Yun Gyu; Shim, Sang Goon; Kim, Young Wook

    2016-01-01

    Background/Aims: The objective of this study was to compare the degree of hepatic enhancement and image quality using contrast media of different iodine concentrations with the same iodine dose. Methods: From July 2011 to June 2013, 50 patients with chronic liver disease who underwent baseline and follow-up 128-slice multidetector computed tomography(MDCT) using contrast media with 350 mg I/mL (group A) and 400 mg I/mL (group B) iodine concentrations were included in this prospective study. The patients were randomly allocated to one of two protocols: 350 mg I/mL initially and then 400 mg I/mL; and 400 mg I/mL initially and then 350 mg I/mL. The bolus tracking technique was used to initiate the arterial phase scan. The computed tomography values of hepatic parenchyma, abdominal aorta and portal vein were measured. The degrees of hepatic and vascular enhancement were rated on a 4-point scale for qualitative assessment. The paired Student t test was used to compare outcome variables. Results: The mean hepatic enhancement was significantly higher in group B than in group A during the portal (p = 0.025) and equilibrium phases (p = 0.021). In all phases, group B had significantly higher mean liver-to-aorta contrast (p < 0.05) and mean visual scores for hepatic and vascular enhancement (p < 0.001). Conclusions: This study showed that a higher iodine concentration (400 mg I/mL) in contrast media was more effective at improving hepatic enhancement in portal and equilibrium phase images and overall image quality using 128-slice MDCT in chronic liver disease patients. PMID:26701234

  10. Cost-effective pediatric head and body phantoms for computed tomography dosimetry and its evaluation using pencil ion chamber and CT dose profiler

    PubMed Central

    Saravanakumar, A.; Vaideki, K.; Govindarajan, K. N.; Jayakumar, S.; Devanand, B.

    2015-01-01

    In the present work, a pediatric head and body phantom was fabricated using polymethyl methacrylate (PMMA) at a low cost when compared to commercially available phantoms for the purpose of computed tomography (CT) dosimetry. The dimensions of head and body phantoms were 10 cm diameter, 15 cm length and 16 cm diameter, 15 cm length, respectively. The dose from a 128-slice CT machine received by the head and body phantom at the center and periphery were measured using a 100 mm pencil ion chamber and 150 mm CT dose profiler (CTDP). Using these values, the weighted computed tomography dose index (CTDIw) and in turn the volumetric CTDI (CTDIv) were calculated for various combinations of tube voltage and current-time product. A similar study was carried out using standard calibrated phantom and the results have been compared with the fabricated ones to ascertain that the performance of the latter is equivalent to that of the former. Finally, CTDIv measured using fabricated and standard phantoms were compared with respective values displayed on the console. The difference between the values was well within the limits specified by Atomic Energy Regulatory Board (AERB), India. These results indicate that the cost-effective pediatric phantom can be employed for CT dosimetry. PMID:26500404

  11. CT -- Body

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Body Computed tomography (CT) of the body uses special x-ray ... Body? What is CT Scanning of the Body? Computed tomography, more commonly known as a CT or CAT ...

  12. Assessment of a CT image of the oral cavity with use of an aid focusing on a neck examination

    NASA Astrophysics Data System (ADS)

    Lee, Hyo-Jong; Goo, Eun-Hoe; Kim, Sung-Soo; Dong, Kyung-Rae; Chung, Woon-Kwan

    2013-11-01

    The aim of this study was to provide clinical information on an oral cavity disease assessment that was conducted using a self-manufactured aid in a computed tomography (CT) oral examination. The study subjects included 30 patients, who were examined using a multi-detector CT (MDCT) 128-slice CT Scanner. Rapidia software was used for quantitative analysis, while a questionnaire and qualitative analysis were used to assess the convenience. The significance was evaluated using a Student's t-test and a Wilcoxon signed rank test. A p value < 0.05 was considered significant. The convenience was evaluated by using a multiple response frequency analysis. The means and the standard deviations, which depended on use of the aid, were 2440.41 ± 4226.26 and 57443.86 ± 12445.91 respectively, the higher values being seen in the image assessment when the aid was used (p = 0.000). In a qualitative evaluation, the means and standard deviations were 2.52 ± 0.44 and 1.62 ± 0.22, respectively, the higher values being shown in the image assessment when the aid was used (p = 0.012). According to the convenience assessment that was conducted using a questionnaire, 80% of the respondents answered that they did not have any inconvenience when using the aid because the scores were 4 points or higher on the scale. In conclusion, the contrast increased when the aid, which enabled a clear identification of the anatomical structure, was inserted to examine the oral cavity. In particular, the patients considered the use of the aid to be convenient. Overall, the aid is recommended for use in a head/neck examination.

  13. 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 ...

  14. Head CT scan

    MedlinePlus

    Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial ... or other growth (mass) Cerebral atrophy (loss of brain tissue) ... with the hearing nerve Stroke or transient ischemic attack (TIA)

  15. Impact of number of repeated scans on model observer performance for a low-contrast detection task in CT

    NASA Astrophysics Data System (ADS)

    Ma, Chi; Yu, Lifeng; Chen, Baiyu; Vrieze, Thomas; Favazza, Christopher; Leng, Shuai; McCollough, Cynthia

    2015-03-01

    In previous investigations on CT image quality, channelized Hotelling observer (CHO) models have been shown to well represent human observer performance in several phantom-based detection/discrimination tasks. In these studies, a large number of independent images was necessary to estimate the expectation images and covariance matrices for each test condition. The purpose of this study is to investigate how the number of repeated scans affects the precision and accuracy of the CHO's performance in a signal-known-exactly detection task. A phantom containing 21 low-contrast objects (3 contrast levels and 7 sizes) was scanned with a 128-slice CT scanner at three dose levels. For each dose level, 100 independent images were acquired for each test condition. All images were reconstructed using filtered-backprojection (FBP) and a commercial iterative reconstruction algorithm. For each combination of dose level and reconstruction method, the low-contrast detectability, quantified with the area under receiver operating characteristic curve (Az), was calculated using a previously validated CHO model. To determine the dependency of CHO performance on the number of repeated scans, the Az value was calculated for different number of channel filters, for each object size and contrast, and for different dose/reconstruction settings using all 100 repeated scans. The Az values were also calculated using randomly selected subsets of the scans (from 10 to 90 scans with an increment of 10 scans). Using the Az from the 100 scans as the reference, the accuracy of Az values calculated from a fewer number of scans was determined and the minimal number of scans was subsequently derived. For the studied signal-known-exactly detection task, results demonstrated that, the minimal number of scans depends on dose level, object size and contrast level, and channel filters.

  16. CT scan

    MedlinePlus

    ... that slides into the center of the CT scanner. Once you are inside the scanner, the machine's x-ray beam rotates around you. Modern spiral scanners can perform the exam without stopping. A computer ...

  17. Technical Note: Measuring contrast- and noise-dependent spatial resolution of an iterative reconstruction method in CT using ensemble averaging

    SciTech Connect

    Yu, Lifeng Vrieze, Thomas J.; Leng, Shuai; Fletcher, Joel G.; McCollough, Cynthia H.

    2015-05-15

    Purpose: The spatial resolution of iterative reconstruction (IR) in computed tomography (CT) is contrast- and noise-dependent because of the nonlinear regularization. Due to the severe noise contamination, it is challenging to perform precise spatial-resolution measurements at very low-contrast levels. The purpose of this study was to measure the spatial resolution of a commercially available IR method using ensemble-averaged images acquired from repeated scans. Methods: A low-contrast phantom containing three rods (7, 14, and 21 HU below background) was scanned on a 128-slice CT scanner at three dose levels (CTDI{sub vol} = 16, 8, and 4 mGy). Images were reconstructed using two filtered-backprojection (FBP) kernels (B40 and B20) and a commercial IR method (sinogram affirmed iterative reconstruction, SAFIRE, Siemens Healthcare) with two strength settings (I40-3 and I40-5). The same scan was repeated 100 times at each dose level. The modulation transfer function (MTF) was calculated based on the edge profile measured on the ensemble-averaged images. Results: The spatial resolution of the two FBP kernels, B40 and B20, remained relatively constant across contrast and dose levels. However, the spatial resolution of the two IR kernels degraded relative to FBP as contrast or dose level decreased. For a given dose level at 16 mGy, the MTF{sub 50%} value normalized to the B40 kernel decreased from 98.4% at 21 HU to 88.5% at 7 HU for I40-3 and from 97.6% to 82.1% for I40-5. At 21 HU, the relative MTF{sub 50%} value decreased from 98.4% at 16 mGy to 90.7% at 4 mGy for I40-3 and from 97.6% to 85.6% for I40-5. Conclusions: A simple technique using ensemble averaging from repeated CT scans can be used to measure the spatial resolution of IR techniques in CT at very low contrast levels. The evaluated IR method degraded the spatial resolution at low contrast and high noise levels.

  18. Technical Note: Measuring contrast- and noise-dependent spatial resolution of an iterative reconstruction method in CT using ensemble averaging

    PubMed Central

    Yu, Lifeng; Vrieze, Thomas J.; Leng, Shuai; Fletcher, Joel G.; McCollough, Cynthia H.

    2015-01-01

    Purpose: The spatial resolution of iterative reconstruction (IR) in computed tomography (CT) is contrast- and noise-dependent because of the nonlinear regularization. Due to the severe noise contamination, it is challenging to perform precise spatial-resolution measurements at very low-contrast levels. The purpose of this study was to measure the spatial resolution of a commercially available IR method using ensemble-averaged images acquired from repeated scans. Methods: A low-contrast phantom containing three rods (7, 14, and 21 HU below background) was scanned on a 128-slice CT scanner at three dose levels (CTDIvol = 16, 8, and 4 mGy). Images were reconstructed using two filtered-backprojection (FBP) kernels (B40 and B20) and a commercial IR method (sinogram affirmed iterative reconstruction, SAFIRE, Siemens Healthcare) with two strength settings (I40-3 and I40-5). The same scan was repeated 100 times at each dose level. The modulation transfer function (MTF) was calculated based on the edge profile measured on the ensemble-averaged images. Results: The spatial resolution of the two FBP kernels, B40 and B20, remained relatively constant across contrast and dose levels. However, the spatial resolution of the two IR kernels degraded relative to FBP as contrast or dose level decreased. For a given dose level at 16 mGy, the MTF50% value normalized to the B40 kernel decreased from 98.4% at 21 HU to 88.5% at 7 HU for I40-3 and from 97.6% to 82.1% for I40-5. At 21 HU, the relative MTF50% value decreased from 98.4% at 16 mGy to 90.7% at 4 mGy for I40-3 and from 97.6% to 85.6% for I40-5. Conclusions: A simple technique using ensemble averaging from repeated CT scans can be used to measure the spatial resolution of IR techniques in CT at very low contrast levels. The evaluated IR method degraded the spatial resolution at low contrast and high noise levels. PMID:25979020

  19. Principles of CT and CT technology.

    PubMed

    Goldman, Lee W

    2007-09-01

    This article provides a review of the basic principles of CT within the context of the evolution of CT. Modern CT technology can be understood as a natural progression of improvements and innovations in response to both engineering problems and clinical requirements. Detailed discussions of multislice CT, CT image quality evaluation, and radiation doses in CT will be presented in upcoming articles in this series. PMID:17823453

  20. Lumbosacral spine CT

    MedlinePlus

    Spinal CT; CT - lumbosacral spine ... In other cases, a CT of the lumbosacral spine may be done after injecting contrast dye into ... of the body. A CT of the lumbosacral spine can evaluate fractures and changes of the spine, ...

  1. Thoracic CT

    MedlinePlus

    ... table that slides into the center of the scanner. Once you are inside the scanner, the machine's x-ray beam rotates around you. ... than 300 pounds, have your doctor contact the scanner operator before the exam. CT scanners have a ...

  2. [CT fluoroscopy].

    PubMed

    Rogalla, P; Juran, R

    2004-07-01

    Percutaneous biopsy of pulmonary nodules requires precise needle placement, with the goal of attaining a secure position of the needle for therapeutic or diagnostic purposes as quickly as possible and with minimal tissue damage along the access route. The requirements from the image guidance system during the intervention are, in addition to universal applicability, a quick reaction time and a user-friendly interface. CT fluoroscopy fulfils these requirements, although radiation protection for the patient and radiologist becomes an important issue. PMID:15232690

  3. MO-E-17A-06: Organ Dose in Abdomen-Pelvis CT: Does TG 111 Equilibrium Dose Concept Better Accounts for KVp Dependence Than Conventional CTDI?

    SciTech Connect

    Li, X; Morgan, A; Davros, W; Dong, F; Primak, A; Segars, W

    2014-06-15

    Purpose: In CT imaging, a desirable quality assurance (QA) dose quantity should account for the dose variability across scan parameters and scanner models. Recently, AAPM TG 111 proposed to use equilibrium dose-pitch product, in place of CT dose index (CTDI100), for scan modes involving table translation. The purpose of this work is to investigate whether this new concept better accounts for the kVp dependence of organ dose than the conventional CTDI concept. Methods: The adult reference female extended cardiac-torso (XCAT) phantom was used for this study. A Monte Carlo program developed and validated for a 128-slice CT system (Definition Flash, Siemens Healthcare) was used to simulate organ dose for abdomenpelvis scans at five tube voltages (70, 80, 100, 120, 140 kVp) with a pitch of 0.8 and a detector configuration of 2x64x0.6 mm. The same Monte Carlo program was used to simulate CTDI100 and equilibrium dose-pitch product. For both metrics, the central and peripheral values were used together with helical pitch to calculate a volume-weighted average, i.e., CTDIvol and (Deq)vol, respectively. Results: While other scan parameters were kept constant, organ dose depended strongly on kVp; the coefficient of variation (COV) across the five kVp values ranged between 70–75% for liver, spleen, stomach, pancreas, kidneys, colon, small intestine, bladder, and ovaries, all of which were inside the primary radiation beam. One-way analysis of variance (ANOVA) for the effect of kVp was highly significant (p=3e−30). When organ dose was normalized by CTDIvol, the COV across the five kVp values reduced to 7–16%. The effect of kVp was still highly significant (p=4e−4). When organ dose was normalized by (Deq)vol, the COV further reduced to 4−12%. The effect of kVp was borderline significant (p=0.04). Conclusion: In abdomen-pelvis CT, TG 111 equilibrium dose concept better accounts for kVp dependence than the conventional CTDI. This work is supported by a faculty startup

  4. Computed Tomography (CT) - Spine

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Spine Computed tomography (CT) of the spine is a diagnostic imaging ... Spine? What is CT Scanning of the Spine? Computed tomography, more commonly known as a CT or CAT ...

  5. Effectiveness of Using Dual-source CT and the Upshot it creates on Both Heart Rate and Image Quality

    PubMed Central

    Selçuk, Tuba; Otçu, Hafize; Yüceler, Zeyneb; Bilgili, Çiğdem; Bulakçı, Mesut; Savaş, Yıldıray; Çelik, Ömer

    2016-01-01

    Background: Early detection of coronary artery disease (CAD) is important because of the high morbidity and mortality rates. As invasive coronary angiography (ICA) is an invasive procedure, an alternative diagnostic method; coronary computed tomography angiography (CTA), has become more widely used by the improvements in detector technology. Aims: In this study, we aimed to examine the accuracy and image quality of high-pitch 128-slice dual-source CTA taking the ICA as reference technique. We also aimed to compare the accuracy and image quality between different heart rate groups of >70 beates per minute (bpm) and ≤70 bpm. Study Design: Retrospective cross-sectional study. Methods: Among 450 patients who underwent coronary CTA with the FLASH spiral technique, performed with a second generation dual-source computed tomography device with a pitch value of 3.2, 102 patients without stent and/or bypass surgery history and clinically suspected coronary artery disease who underwent ICA within 15 days were enrolled. Image quality was assessed by two independent radiologists using a 4-point scale (1=absence of any artifacts- 4=non-evaluable). A stenosis >50% was considered significant on a per-segment, per-vessel, and per-patient basis and ICA was considered the reference method. Radiation doses were determined using dose length product (DLP) values detected by the computed tomography (CT) device. In addition, patients were classified into two groups according to their heart rates as ≤70 bpm (73 patients) and >70 bpm (29 patients). The relation between the diagnostic accuracy and heart rate groups were evaluated. Results: Overall, 1495 (98%) coronary segments were diagnostic in 102 patients (32 male, 70 female, mean heart rate: 65 bpm). There was a significant correlation between image quality and mean heart rate in the right coronary artery (RCA) segments. The effective radiation dose was 0.98±0.09 mili Sievert (mSv). On a per-patient basis, sensitivity, specificity

  6. Head CT (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 ...

  7. 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 ...

  8. CT appearance of splenosis

    SciTech Connect

    Mendelson, D.S.; Cohen, B.A.; Armas, R.R.

    1982-12-01

    Splenosis is an unusual complication of splenic trauma. The computed tomographic (CT) appearance of splenosis is described. One should consider this diagnosis when faced with a history of splenic trauma and multiple round or oval masses at CT.

  9. NETL CT Imaging Facility

    ScienceCinema

    None

    2014-05-21

    NETL's CT Scanner laboratory is equipped with three CT scanners and a mobile core logging unit that work together to provide characteristic geologic and geophysical information at different scales, non-destructively.

  10. NETL CT Imaging Facility

    SciTech Connect

    2013-09-04

    NETL's CT Scanner laboratory is equipped with three CT scanners and a mobile core logging unit that work together to provide characteristic geologic and geophysical information at different scales, non-destructively.

  11. Orbit CT scan

    MedlinePlus

    ... results may mean: Bleeding Broken eye socket bone Graves disease Infection Tumor Risks CT scans and other x- ... Livingstone; 2014:chap 66. Read More CT scan Graves disease Tumor Update Date 1/18/2015 Updated by: ...

  12. Marketing cardiac CT programs.

    PubMed

    Scott, Jason

    2010-01-01

    There are two components of cardiac CT discussed in this article: coronary artery calcium scoring (CACS) and coronary computed tomography angiography (CCTA).The distinctive advantages of each CT examination are outlined. In order to ensure a successful cardiac CT program, it is imperative that imaging facilities market their cardiac CT practices effectively in order to gain a competitive advantage in this valuable market share. If patients receive quality care by competent individuals, they are more likely to recommend the facility's cardiac CT program. Satisfied patients will also be more willing to come back for any further testing. PMID:22276376

  13. Practical CT dosimetry

    SciTech Connect

    Yoshizumi, T.T.; Suneja, S.K.; Teal, J.S. )

    1989-07-01

    The dose from computed tomography (CT) examinations is not negligible from a radiation safety standpoint. Occasionally, one encounters a case in which an unsuspected pregnant woman undergoes a CT pelvic scan, and the radiologist is required to estimate the dose to the fetus. This article addresses practical methods of CT dosimetry with a specific discussion on fetal dose estimate. Three methods are described: (1) the use of a dose chart, (2) the pencil ionization chamber method, and (3) the thermoluminescence dosimetry (TLD) method.

  14. CT findings in leukemia

    SciTech Connect

    Heiberg, E.; Wolverson, M.K.; Sundaram, M.; Shields, J.B.

    1984-12-01

    Review of 84 computed tomographic (CT) scans in leukemic patients demonstrate a wide spectrum of abnormalities. Findings caused by leukemia were lymphadenopathy, visceral enlargement, focal defects, and tissue infiltration. Hemorrhage was by far the most common complication and could usually be characterized on the noncontrast CT scan. The distinction between old hematomas, foci of infection, and leukemia infiltration could not be made with certainty without CT-guided aspiration. Unusual instances of sepsis, such as microabscesses of the liver and typhlitis, were seen.

  15. PET/CT Artifacts

    PubMed Central

    Blodgett, Todd M.; Mehta, Ajeet S.; Mehta, Amar S.; Laymon, Charles M.; Carney, Jonathan; Townsend, David W.

    2014-01-01

    There are several artifacts encountered in PET/CT imaging, including attenuation correction (AC) artifacts associated with using CT for attenuation correction. Several artifacts can mimic a 2-deoxy-2-[18F] fluoro-D-glucose (FDG) avid malignant lesions and therefore recognition of these artifacts is clinically relevant. Our goal was to identify and characterize these artifacts and also discuss some protocol variables that may affect image quality in PET/CT. PMID:21237418

  16. CT of Gastric Emergencies.

    PubMed

    Guniganti, Preethi; Bradenham, Courtney H; Raptis, Constantine; Menias, Christine O; Mellnick, Vincent M

    2015-01-01

    Abdominal pain, nausea, and vomiting are common presenting symptoms among adult patients seeking care in the emergency department, and, with the increased use of computed tomography (CT) to image patients with these complaints, radiologists will more frequently encounter a variety of emergent gastric pathologic conditions on CT studies. Familiarity with the CT appearance of emergent gastric conditions is important, as the clinical presentation is often nonspecific and the radiologist may be the first to recognize gastric disease as the cause of a patient's symptoms. Although endoscopy and barium fluoroscopy remain important tools for evaluating patients with suspected gastric disease in the outpatient setting, compared with CT these modalities enable less comprehensive evaluation of patients with nonspecific complaints and are less readily available in the acute setting. Endoscopy is also more invasive than CT and has greater potential risks. Although the mucosal detail of CT is relatively poor compared with barium fluoroscopy or endoscopy, CT can be used with the appropriate imaging protocols to identify inflammatory conditions of the stomach ranging from gastritis to peptic ulcer disease. In addition, CT can readily demonstrate the various complications of gastric disease, including perforation, obstruction, and hemorrhage, which may direct further clinical, endoscopic, or surgical management. We will review the normal anatomy of the stomach and discuss emergent gastric disease with a focus on the usual clinical presentation, typical imaging appearance, and differentiating features, as well as potential imaging pitfalls. PMID:26562229

  17. Spiral CT: vascular applications.

    PubMed

    Rankin, S C

    1998-08-01

    Recent technical advances in CT have renewed interest in the development of CT angiography (CTA). CT angiography is a minimally invasive method of visualising the vascular system and is becoming an alternative to conventional arteriography in some situations. Spiral technology allows a volume of data to be obtained on a single breath-hold with no respiratory misregistration. Fast machines with second or subsecond acquisition times mean the images are obtained while there are high circulating levels of contrast medium giving peak vascular opacification from a peripheral intravenous injection. Accurate timing will ensure either the arterial or venous phase is imaged. Multiple overlapping axial images can be obtained from the data set with no increase in radiation dose to the patient and from these scans computer generated multiplanar and 3D images are obtained which can be viewed from numerous angles. CT angiography can be performed more quickly, less invasively and at reduced cost compared to conventional angiography. PMID:9717621

  18. Pediatric CT Scans

    Cancer.gov

    The Radiation Epidemiology Branch and collaborators have initiated a retrospective cohort study to evaluate the relationship between radiation exposure from CT scans conducted during childhood and adolescence and the subsequent development of cancer.

  19. Thoracic spine CT scan

    MedlinePlus

    ... that slides into the center of the CT scanner. Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.) A computer ...

  20. Head CT scan

    MedlinePlus

    ... that slides into the center of the CT scanner. While inside the scanner, the machine's x-ray beam rotates around you. ... breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and ...

  1. Arm CT scan

    MedlinePlus

    CAT scan - arm; Computed axial tomography scan - arm; Computed tomography scan - arm; CT scan - arm ... Mosby; 2013:chap 57. Shaw AS, Prokop M. Computed tomography. In: Adam A, Dixon AK, Gillard JH, Schaefer- ...

  2. Heart CT scan

    MedlinePlus

    CAT scan - heart; Computed axial tomography scan - heart; Computed tomography scan - heart; Calcium scoring; Multi-detector CT scan - heart; Electron beam computed tomography - heart; Agaston score; Coronary calcium scan

  3. Sinus CT scan

    MedlinePlus

    CAT scan - sinus; Computed axial tomography scan - sinus; Computed tomography scan - sinus; CT scan - sinus ... 2014:chap 67. Shaw AS, Dixon AK. Multidetector computed tomography. In: Adam A, Dixon AK, eds. Grainger & Allison's ...

  4. Leg CT scan

    MedlinePlus

    CAT scan - leg; Computed axial tomography scan - leg; Computed tomography scan - leg; CT scan - leg ... Saunders; 2012:chap 11. Shaw AS, Prokop M. Computed tomography. In: Adam A, Dixon AK, Gillard JH, Schaefer- ...

  5. Pelvic CT scan

    MedlinePlus

    CAT scan - pelvis; Computed axial tomography scan - pelvis; Computed tomography scan - pelvis; CT scan - pelvis ... gov/pubmed/18381118 . Shaw AS, Dixon AK. Multidetector computed tomography. In: Grainger RC, Allison D, Adam, Dixon AK, ...

  6. Shoulder CT scan

    MedlinePlus

    CAT scan - shoulder; Computed axial tomography scan - shoulder; Computed tomography scan - shoulder; CT scan - shoulder ... Mosby; 2012:chap 57. Shaw AS, Prokop M. Computed tomography. In: Adam A, Dixon AK, Gillard JH, Schaefer- ...

  7. Lumbar spine CT scan

    MedlinePlus

    CAT scan - lumbar spine; Computed axial tomography scan - lumbar spine; Computed tomography scan - lumbar spine; CT - lower back ... stopping.) A computer creates separate images of the spine area, called slices. These images can be stored, ...

  8. Chest CT Scan

    MedlinePlus

    ... pictures to create a very detailed, three-dimensional (3D) model of organs. Sometimes, a substance called contrast dye is injected into a vein in your arm for the CT scan. This substance highlights areas in your chest, which ...

  9. CT Colonography (Virtual Colonoscopy)

    MedlinePlus

    ... into the colon using a hand-held squeeze bulb. Sometimes an electronic pump is used to deliver ... When you enter the CT scanner room, special light lines may be seen projected onto your body, ...

  10. CT Angiography (CTA)

    MedlinePlus

    ... CT Angiography? Angiography is a minimally invasive medical test that helps physicians diagnose and treat medical conditions. Angiography uses one of three imaging technologies and, in most cases, a contrast material injection ...

  11. Your Radiologist Explains CT Colonography

    MedlinePlus Videos and Cool Tools

    ... About this Site RadiologyInfo.org is produced by: Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual ... to allow for inflation with air while CT images are being taken. If you’re scheduled for ...

  12. Dose management in CT facility

    PubMed Central

    Tsapaki, V; Rehani, M

    2007-01-01

    Computed Tomography (CT) examinations have rapidly increased in number over the last few years due to recent advances such as the spiral, multidetector-row, CT fluoroscopy and Positron Emission Tomography (PET)-CT technology. This has resulted in a large increase in collective radiation dose as reported by many international organisations. It is also stated that frequently, image quality in CT exceeds the level required for confident diagnosis. This inevitably results in patient radiation doses that are higher than actually required, as also stressed by the US Food and Drug Administration (FDA) regarding the CT exposure of paediatric and small adult patients. However, the wide range in exposure parameters reported, as well as the different CT applications reveal the difficulty in standardising CT procedures. The purpose of this paper is to review the basic CT principles, outline the recent technological advances and their impact in patient radiation dose and finally suggest methods of radiation dose optimisation. PMID:21614279

  13. Pelvic CT scan

    MedlinePlus

    ... that slides into the center of the CT scanner. Once you are inside the scanner, the machine's x-ray beam rotates around you. ... weight limit. Too much weight can damage the scanner's working parts. You will be asked to remove ...

  14. PET/CT imaging artifacts.

    PubMed

    Sureshbabu, Waheeda; Mawlawi, Osama

    2005-09-01

    The purpose of this paper is to introduce the principles of PET/CT imaging and describe the artifacts associated with it. PET/CT is a new imaging modality that integrates functional (PET) and structural (CT) information into a single scanning session, allowing excellent fusion of the PET and CT images and thus improving lesion localization and interpretation accuracy. Moreover, the CT data can also be used for attenuation correction, ultimately leading to high patient throughput. These combined advantages have rendered PET/CT a preferred imaging modality over dedicated PET. Although PET/CT imaging offers many advantages, this dual-modality imaging also poses some challenges. CT-based attenuation correction can induce artifacts and quantitative errors that can affect the PET emission images. For instance, the use of contrast medium and the presence of metallic implants can be associated with focal radiotracer uptake. Furthermore, the patient's breathing can introduce mismatches between the CT attenuation map and the PET emission data, and the discrepancy between the CT and PET fields of view can lead to truncation artifacts. After reading this article, the technologist should be able to describe the principles of PET/CT imaging, identify at least 3 types of image artifacts, and describe the differences between PET/CT artifacts of different causes: metallic implants, respiratory motion, contrast medium, and truncation. PMID:16145223

  15. Seventh-generation CT

    NASA Astrophysics Data System (ADS)

    Besson, G. M.

    2016-03-01

    A new dual-drum CT system architecture has been recently introduced with the potential to achieve significantly higher temporal resolution than is currently possible in medical imaging CT. The concept relies only on known technologies; in particular rotation speeds several times higher than what is possible today could be achieved leveraging typical x-ray tube designs and capabilities. However, the architecture lends itself to the development of a new arrangement of x-ray sources in a toroidal vacuum envelope containing a rotating cathode ring and a (optionally rotating) shared anode ring to potentially obtain increased individual beam power as well as increase total exposure per rotation. The new x-ray source sub-system design builds on previously described concepts and could make the provision of multiple conventional high-power cathodes in a CT system practical by distributing the anode target between the cathodes. In particular, relying on known magnetic-levitation technologies, it is in principle possible to more than double the relative speed of the electron-beam with respect to the target, thus potentially leading to significant individual beam power increases as compared to today's state-of-the-art. In one embodiment, the proposed design can be naturally leveraged by the dual-drum CT concept previously described to alleviate the problem of arranging a number of conventional rotating anode-stem x-ray tubes and power conditioners on the limited space of a CT gantry. In another embodiment, a system with three cathodes is suggested leveraging the architecture previously proposed by Franke.

  16. Concha bullosa: CT evaluation.

    PubMed

    Zinreich, S J; Mattox, D E; Kennedy, D W; Chisholm, H L; Diffley, D M; Rosenbaum, A E

    1988-01-01

    Aeration of the middle turbinate, termed "concha bullosa," is a common anatomical variant of intranasal anatomy. Of 320 patients evaluated for sinus disease with coronal CT, 34% had concha bullosa on at least one side. The overall incidence of inflammatory disease in the ostiomeatal complex in these symptomatic patients was not different between those with and without concha bullosa. However, there were many cases in which an abnormally large middle turbinate appeared to obstruct the ostiomeatal complex causing secondary infection of the ethmoid, frontal, and maxillary sinuses. Obstruction of drainage of the concha bullosa itself can lead to mucocele formation. Furthermore, the presence of a concha bullosa has important implications for the technique of endoscopic surgery used in the management of the sinus disease. The anatomy, pathophysiology, and CT findings in patients with concha bullosa are reviewed. PMID:3170840

  17. Quantitative micro-CT

    NASA Astrophysics Data System (ADS)

    Prevrhal, Sven

    2005-09-01

    Micro-CT for bone structural analysis has progressed from an in-vitro laboratory technique to devices for in-vivo assessment of small animals and the peripheral human skeleton. Currently, topological parameters of bone architecture are the primary goals of analysis. Additional measurement of the density or degree of mineralization (DMB) of trabecular and cortical bone at the microscopic level is desirable to study effects of disease and treatment progress. This information is not commonly extracted because of the challenges of accurate measurement and calibration at the tissue level. To assess the accuracy of micro-CT DMB measurements in a realistic but controlled situation, we prepared bone-mimicking watery solutions at concentrations of 100 to 600 mg/cm3 K2PO4H and scanned them with micro-CT, both in glass vials and microcapillary tubes with inner diameters of 50, 100 and 150 μm to simulate trabecular thickness. Values of the linear attenuation coefficients μ in the reconstructed image are commonly affected by beam hardening effects for larger samples and by partial volume effects for small volumes. We implemented an iterative reconstruction technique to reduce beam hardening. Partial voluming was sought to be reduced by excluding voxels near the tube wall. With these two measures, improvement on the constancy of the reconstructed voxel values and linearity with solution concentration could be observed to over 90% accuracy. However, since the expected change in real bone is small more measurements are needed to confirm that micro-CT can indeed be adapted to assess bone mineralization at the tissue level.

  18. CT number variations in micro CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tu, Shu-Ju; Hsieh, Hui-Ling; Chao, Tsi-Chian

    2008-03-01

    CT numbers can be directly computed from the linear attenuation coefficients in the reconstructed CT images and are correlated to the electron densities of the chemical elements with specific atomic numbers. However, the computed CT numbers can be varied when different imaging parameters are used. Phantoms composed of clinically relevant and tissue-equivalent materials (lung, bone, muscle, and adipose) were scanned with a commercial circular-scanning micro CT imager. This imaging system is composed with a micro-focused x-ray tube and charged-coupled device (CCD) camera as the detector. The mean CT numbers and the corresponding standard deviations in terms of Hounsfield units were then computed from a pre-defined region of interest located within the reconstructed volumetric images. The variations of CT number were then identified from a series of imaging parameters. Those parameters include imaging acquisition modes (e.g., the metal filter used in the x-ray tube), reconstruction methods (e.g., Feldkamp and iterative algorithm), and post-image processing techniques (e.g., ring artifact, beam-hardening artifact, and smoothing processing). These variations of CT numbers are useful and important in tissue characterization, quantitative bone structure analysis, bone marrow density evaluation, and Monte Carlo dose calculations for the pilot small animal study when micro CT imaging systems are employed. Also these variations can be used as the quantification for the performance of the micro CT imaging systems.

  19. Chronic osteomyelitis examined by CT

    SciTech Connect

    Wing, V.W.; Jeffrey, R.B. Jr.; Federle, M.P.; Helms, C.A.; Trafton, P.

    1985-01-01

    CT examination of 25 patients who had acute exacerbations of chronic osteomyelitis allowed for the correct identification of single or multiple sequestra in 14 surgical patients. Plain radiographs were equivocal for sequestra in seven of these patients, because the sequestra were too small or because diffuse bony sclerosis was present. CT also demonstrated a foreign body and five soft tissue abscesses not suspected on the basis of plain radiographs. CT studies, which helped guide the operative approach, were also useful in treating those patients whose plain radiographs were positive for sequestra. The authors review the potential role of CT in evaluating patients with chronic osteomyelitis.

  20. CT findings of atrial myxoma

    SciTech Connect

    Tsuchiya, F.; Kohno, A.; Saitoh, R.; Shigeta, A.

    1984-04-01

    The computed tomographic (CT) appearance of six atrial myxomas was analyzed. Five of the myxomas were located in the left atrium and one was in the right atrium. The margin of the myxoma was at least slightly lobulated in five cases and the content was inhomogeneous in all. Calcification was demonstrated in three cases. The site of attachment of the myxoma was demonstrated by CT to be the arial septum in all cases. The CT finding correlated well with the operative findings. It is concluded that it is possible with CT to diagnose atrial myxoma by the location and nature of the intracardiac mass and to differentiate it from thrombus.

  1. Nano-CT Scanning

    NASA Astrophysics Data System (ADS)

    Masschaele, B.

    Tomography is a non-destructive research technique which allows investigating the internal structure of objects in 3D . The "centre for X-ray tomography (UGCT)" of the Ghent University has developed a modular X-ray micro/nanoCT scanner which is used for multi-disciplinary research. In this paper we give an overview of the different components of the UGCT scanner with special attention to the X-ray imaging detectors. Also the software tools for data reconstruction and analysis and some obtained results are discussed.

  2. PET/CT: fundamental principles.

    PubMed

    Seemann, Marcus D

    2004-05-28

    Positron emission tomography (PET) facilitates the evaluation of metabolic and molecular characteristics of a wide variety of cancers, but is limited in its ability to visualize anatomical structures. Computed tomography (CT) facilitates the evaluation of anatomical structures of cancers, but can not visualize their metabolic and molecular aspects. Therefore, the combination of PET and CT provides the ability to accurately register metabolic and molecular aspects of disease with anatomical findings, adding further information to the diagnosis and staging of tumors. The recent generation of high performance PET/CT scanners combines a state of the art full-ring 3D PET scanner and a high-end 16-slice CT scanner. In PET/CT scanners, a CT examination is used for attenuation correction of PET images rather than standard transmission scanning using superset 68 Ge sources. This reduces the examination time, but metallic objects and contrast agents that alter the CT image quality and quantitative measurements of standardized uptake values (SUV) may lead to artifacts in the PET images. Hybrid PET/CT imaging will be very important in oncological applications in the decades to come, and possibly for use in cancer screening and cardiac imaging. PMID:15257877

  3. Quantifying tumour heterogeneity with CT

    PubMed Central

    Miles, Kenneth A.

    2013-01-01

    Abstract Heterogeneity is a key feature of malignancy associated with adverse tumour biology. Quantifying heterogeneity could provide a useful non-invasive imaging biomarker. Heterogeneity on computed tomography (CT) can be quantified using texture analysis which extracts spatial information from CT images (unenhanced, contrast-enhanced and derived images such as CT perfusion) that may not be perceptible to the naked eye. The main components of texture analysis can be categorized into image transformation and quantification. Image transformation filters the conventional image into its basic components (spatial, frequency, etc.) to produce derived subimages. Texture quantification techniques include structural-, model- (fractal dimensions), statistical- and frequency-based methods. The underlying tumour biology that CT texture analysis may reflect includes (but is not limited to) tumour hypoxia and angiogenesis. Emerging studies show that CT texture analysis has the potential to be a useful adjunct in clinical oncologic imaging, providing important information about tumour characterization, prognosis and treatment prediction and response. PMID:23545171

  4. Coronary vasospasm during CT angiography.

    PubMed

    Nakahara, Takehiro; Toyama, Takuji; Tsushima, Yoshito; Kurabayashi, Masahiko

    2014-01-01

    A 71-year-old man, a heavy smoker, was admitted for evaluation of "chest oppression" after every dinner. Cardiac CT with a beta-blocker showed coronary stenosis in the left circumflex. Although adenosine triphosphate-stress perfusion single-photon emission CT revealed no ischemia, Holter electrocardiography belatedly indicated an ST elevation associated with his symptoms while smoking. He was diagnosed to have vasospastic angina. Cardiac CT without a beta-blocker showed thin diffuse plaque and negative remolding without any significant stenosis at the same site. Asian patients have a tendency to develop vasospastic angina. Although beta-blockers are recommended for cardiac CT, the routine administration of beta-blockers in cardiac CT may have some risk for such cases. PMID:25065860

  5. Thoracic textilomas: CT findings*

    PubMed Central

    Machado, Dianne Melo; Zanetti, Gláucia; Araujo, Cesar Augusto; Nobre, Luiz Felipe; Meirelles, Gustavo de Souza Portes; Pereira e Silva, Jorge Luiz; Guimarães, Marcos Duarte; Escuissato, Dante Luiz; Souza, Arthur Soares; Hochhegger, Bruno; Marchiori, Edson

    2014-01-01

    OBJECTIVE: The aim of this study was to analyze chest CT scans of patients with thoracic textiloma. METHODS: This was a retrospective study of 16 patients (11 men and 5 women) with surgically confirmed thoracic textiloma. The chest CT scans of those patients were evaluated by two independent observers, and discordant results were resolved by consensus. RESULTS: The majority (62.5%) of the textilomas were caused by previous heart surgery. The most common symptoms were chest pain (in 68.75%) and cough (in 56.25%). In all cases, the main tomographic finding was a mass with regular contours and borders that were well-defined or partially defined. Half of the textilomas occurred in the right hemithorax and half occurred in the left. The majority (56.25%) were located in the lower third of the lung. The diameter of the mass was ≤ 10 cm in 10 cases (62.5%) and > 10 cm in the remaining 6 cases (37.5%). Most (81.25%) of the textilomas were heterogeneous in density, with signs of calcification, gas, radiopaque marker, or sponge-like material. Peripheral expansion of the mass was observed in 12 (92.3%) of the 13 patients in whom a contrast agent was used. Intraoperatively, pleural involvement was observed in 14 cases (87.5%) and pericardial involvement was observed in 2 (12.5%). CONCLUSIONS: It is important to recognize the main tomographic aspects of thoracic textilomas in order to include this possibility in the differential diagnosis of chest pain and cough in patients with a history of heart or thoracic surgery, thus promoting the early identification and treatment of this postoperative complication. PMID:25410842

  6. Validation of CT doses of SPECT/CT and PET/CT hybrid devices: lessons learned.

    PubMed

    Sera, Terez; Porubszky, Tamas; Papos, Miklos; Elek, Richard; Besenyi, Zsuzsanna; Gion, Katalin; Bartha, Andras; Pellet, Sandor; Pavics, Laszlo

    2014-05-01

    The aim of the study was to check the validity of computed tomographic (CT) doses exhibited by SPECT/CT and PET/CT hybrid devices. Dose measurements were taken from four SPECT/CT and four PET/CT cameras commercially available from different manufacturers. A calibrated ionization chamber was placed in whole-body or head phantoms for the acquisition of CT images with clinically used parameters. Computed tomography dose index (CTDIvol) values were calculated according to the IEC 60601-2-44:1999 formula. The measured CTDIvol doses were compared with those preprogrammed by the manufacturer. In the case of the whole-body phantom, the differences between the measured and displayed values varied between -31 and +24% [European document RP162 (2012) sets up the limit for acceptance criterion as ±20%]. The head phantom data showed either an agreement between -10 and +24%, or an underestimation by two-fold. The latter seemed to be because, while preprogramming the doses, the manufacturer had used the whole-body phantom instead of a proper head phantom. The results of the work demonstrate the need for individual dosimetric calibration of every single X-ray tube. Dosimetric checks should be included in the regular quality control programmes of the SPECT/CT and PET/CT devices. Special attention should be paid to head-and-neck and paediatric protocols, in which the use of a head phantom is recommended for dose calibration. PMID:24499726

  7. CT Angiography after 20 Years

    PubMed Central

    Rubin, Geoffrey D.; Leipsic, Jonathon; Schoepf, U. Joseph; Fleischmann, Dominik; Napel, Sandy

    2015-01-01

    Through a marriage of spiral computed tomography (CT) and graphical volumetric image processing, CT angiography was born 20 years ago. Fueled by a series of technical innovations in CT and image processing, over the next 5–15 years, CT angiography toppled conventional angiography, the undisputed diagnostic reference standard for vascular disease for the prior 70 years, as the preferred modality for the diagnosis and characterization of most cardiovascular abnormalities. This review recounts the evolution of CT angiography from its development and early challenges to a maturing modality that has provided unique insights into cardiovascular disease characterization and management. Selected clinical challenges, which include acute aortic syndromes, peripheral vascular disease, aortic stent-graft and transcatheter aortic valve assessment, and coronary artery disease, are presented as contrasting examples of how CT angiography is changing our approach to cardiovascular disease diagnosis and management. Finally, the recently introduced capabilities for multispectral imaging, tissue perfusion imaging, and radiation dose reduction through iterative reconstruction are explored with consideration toward the continued refinement and advancement of CT angiography. PMID:24848958

  8. [CT colonography in daily practice].

    PubMed

    Stoker, Jaap; Dekker, Evelien

    2013-01-01

    The sensitivity of computed tomography (CT) colonography for colorectal carcinoma and large polyps (≥ 10 mm) is comparable with that of colonoscopy. Acceptance in symptomatic patients is higher than for colonoscopy. The accuracy of CT colonography for polyps of 6-9 mm, for flat polyps and in particular for polyps < 6 mm is lower than for colonoscopy. Indication for CT colonography depends on the a prior chance of finding something relevant, as colonoscopy is necessary in the case of relevant findings. CT colonography can be an alternative to colonoscopy in patients with symptoms consistent with colorectal cancer when colonoscopy is not possible or appears incomplete. It can be used as primary technique in older patients with comorbidity and low a prior chance of relevant findings. CT colonography is less appropriate for surveillance as the accuracy for flat polyps is lower. CT colonography is not suitable in hereditary syndromes due to the lower accuracy for polyps < 10 mm. CT colonography can be a good alternative in patients with irritable bowel syndrome in the case of a low suspicion of colorectal cancer. PMID:24168847

  9. Reducing CT dose in myocardial perfusion SPECT/CT.

    PubMed

    O'Shaughnessy, Emma; Dixon, Kat L

    2015-11-01

    The aim of this study was to reduce the radiation dose arising from computed tomography (CT) attenuation correction to single photon emission computed tomography myocardial perfusion imaging studies without adversely affecting its accuracy. Using the Perspex CTDI phantom with the Xi detector to measure dose, CT scans were acquired using the Siemens Symbia T over the full range of CT settings available. Using the default setting 'AECmean', the measured dose at the centre of the phantom was 1.68 mGy and the breast dose from the scout view was 0.30 mGy. The lowest dose was achieved using the dose modulation setting in which the doses were reduced to 1.21 mGy and undetectable (<0.01 mGy), respectively. To observe the effect of changing these settings, 30 patients received a stress scan with default CT settings and a rest scan utilizing single photon emission computed tomography-guided CT and the dose modulation CT settings. Results showed a mean effective dose reduction of 23.6%. The dose reduction was greatest for larger patients, with the largest dose reduction for one patient being 72%. There was no apparent difference in attenuation correction between the two sets of resultant images. These new lower-dose settings are now applied to all clinical myocardial perfusion imaging studies. PMID:26302461

  10. Kilovoltage CT using a linac-CT scanner combination.

    PubMed

    Thieke, C; Malsch, U; Schlegel, W; Debus, J; Huber, P; Bendl, R; Thilmann, C

    2006-09-01

    Modern radiotherapy techniques such as intensity modulation are capable of generating complex dose distributions whose high dose areas tightly conform to the tumour target volume, sparing critical organs even when they are located in close proximity. This potential can only be exploited to its full extent when the accumulated dose actually delivered over the complete treatment course is sufficiently close to the dose computed on the initial CT scan used for treatment planning. Exact patient repositioning is mandatory, but also other sources of error, e.g. changes of the patient's anatomy under therapy, should be taken into account. At the German Cancer Research Center, we use a combination of a linear accelerator and a CT scanner installed in one room and sharing the same couch. It allows the quantification and correction of interfractional variations between planning and treatment delivery. In this paper, we describe treatments of prostate, paraspinal and head and neck tumours. All patients were immobilized by customized fixation devices and treated in a stereotactic setup. For each patient, frequent CT scans were taken during the treatment course. Each scan was compared with the original planning CT using manual checks and automatic rigid matching algorithms. Depending on the individual case, the adaptation to variations was carried out offline after several fractions or in real-time between the CT scan and linac irradiation. We discuss the techniques for detecting and correcting interfractional errors and outline the procedural steps of a linac-CT scanner-supported radiation treatment course. PMID:16980687

  11. Children, CT Scan and Radiation

    PubMed Central

    Bajoghli, Morteza; Bajoghli, Farshad; Tayari, Nazila; Rouzbahani, Reza

    2010-01-01

    Children are more sensitive to radiation than adults. Computerized tomography (CT) consists of 25 % of all medical imaging. It was estimated that more than 2% of all carcinomas in the USA are due to CT scans. There is an ongoing focus on the reduction of CT scan radiation dose. Awareness about risk-benefits of CT has increased. Reduction of radiological exam is an important issue because the accumulation effects of radiation can be hazardous. In addition, proper protocol should be followed for diagnostic procedures of ionization radiation and computerized tomography. Effective radiation dose should range from 0.8 to 10.5 millisievert. The same protocol should be followed in different hospitals as well. Basic principles of radiation protection should be monitored. As much as possible, both technician and radiologist must be present during computerized tomography for children, and MRI and ultrasound should be replaced if possible. PMID:21566776

  12. Adrenal cortex dysfunction: CT findings

    SciTech Connect

    Huebener, K.H.; Treugut, H.

    1984-01-01

    The computed tomographic appearance of the adrenal gland was studied in 302 patients with possible endocrinologic disease and 107 patients undergoing CT for nonendocrinologic reasons. Measurements of adrenal size were also made in 100 adults with no known adrenal pathology. CT proved to be a sensitive diagnostic tool in combination with clinical studies. When blood hormone levels are increased, CT can differentiate among homogeneous organic hyperplasia, nodular hyperplasia, benign adenoma, and malignant cortical adenoma. When blood hormone levels are decreased, CT can demonstrate hypoplasia or metastatic tumorous destruction. Calcifications can be demonstrated earlier than on plain radiographs. When hormone elimination is increased, the morphologic substrate can be identified; tumorous changes can be localized and infiltration of surrounding organs recognized.

  13. CT Demonstration of Caput Medusae

    ERIC Educational Resources Information Center

    Weber, Edward C.; Vilensky, Joel A.

    2009-01-01

    Maximum intensity and volume rendered CT displays of caput medusae are provided to demonstrate both the anatomy and physiology of this portosystemic shunt associated with portal hypertension. (Contains 2 figures.)

  14. CT Perfusion of the Head

    MedlinePlus

    ... scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the ... being studied can then be examined on a computer monitor, printed or transferred to a CD. CT ...

  15. CT of the pulmonary ligament

    SciTech Connect

    Godwin, J.D.; Vock, P.; Osborne, D.R.

    1983-08-01

    Most computed tomographic (CT) scans of the chest show the inferior pulmonary ligament and an associated septum in the lower lobe, although CT descriptions of these structures have not been reported. Conventional radiography of the ligament has relied on indirect signs: the position of the lower lobe in the presence of pneumothorax or pleural effusion, soft-tissue peaks along the upper surface of the diaphragm, and the rare traumatic paramediastinal pneumatocele (attributed to air in the ligament). CT clarifies the anatomic relations of the ligament and alterations caused by pleural effusion and pneumothorax. The ligament is probably responsible for some long linear shadows at the lung bases, and CT helps to distinguish these from scars, walls of bullae, and normal structures such as the phrenic nerve and the interlobar fissures.

  16. Multiplanar CT of the spine

    SciTech Connect

    Rothman, S.L.G.; Glenn, W.V.

    1985-01-01

    This book contains 16 chapters. Some of the topics are: CT of the Sacrum, The Postoperative Spine, Film Organizations and Case Reporting, Degeneration and Disc Disease of the Intervertebral Joint, Lumbar Spinal Stenosis, and Cervical and Thoracic Spine.

  17. Multiple myeloma: evaluation by CT

    SciTech Connect

    Schreiman, J.S.; McLeod, R.A.; Kyle, R.A.; Beabout, J.W.

    1985-02-01

    Although patients who have multiple myeloma usually have straightforward clinical symptoms and corroborative radiographs, in some instances, these patients will present atypically, with symptoms suggesting active disease but radiographs that are normal or nonspecific. The authors reviewed the records of 32 patients who had documented multiple myeloma and had undergone CT examinations, assessing the value of those examinations. Although CT is not indicated in all patients who have multiple myeloma, it is especially useful in patients who have bone pain and normal or nonspecific radiographs. CT provided confirmatory information in all cases in which lesions were seen on radiographs. CT also frequently demonstrated a greater extent of disease than could be appreciated on the radiographs.

  18. Ct2 Bladder Cancer.

    PubMed

    Soloway, Mark S

    2016-09-01

    The patient is an 80-year-old man who presented with gross hematuria. His past medical history indicates he was a cigarette smoker with 50 pack/years. He was successfully treated for carcinoma of the lung 7 years ago. He received chemotherapy, radiation, and surgery. He has mild COPD but has a good performance status. His laboratory studies do not indicate any abnormalities in terms of renal function. He does not have any significant cardiac disease. He has a medium build. He had prostate cancer and underwent a successful radical prostatectomy 10 years ago. His PSA is undetectable. He has some urinary incontinence and wears two pads/day. He underwent the appropriate investigations for gross hematuria. A CT scan of the abdomen and pelvis was normal with the exception of a 4-cm posterior mass in the bladder. There was no hydronephrosis and no enlarged lymph nodes. He underwent a transurethral resection of a solitary bladder tumor performed by another urologist. The tumor was described as large and sessile. It was located on the posterior wall and was approximately 4 cm. The bimanual examination did not reveal a mass. The pathology report stated that the tumor was a high-grade urothelial carcinoma with invasion into the muscularis propria. There was no lymphovascular invasion. I performed a reTURBT, and at that procedure, I did not identify any obvious tumor but the prior resection site was evident. I resected the prior tumor site quite extensively both in depth and width. The pathology revealed only focal carcinoma in situ. There was ample muscle in the specimen and there was some fat as well. As stated, they were free of any cancer. The patient is receptive to any treatment approach. PMID:27457483

  19. Cardiac cone-beam CT

    SciTech Connect

    Manzke, Robert . E-mail: robert.manzke@philips.com

    2005-10-15

    This doctoral thesis addresses imaging of the heart with retrospectively gated helical cone-beam computed tomography (CT). A thorough review of the CT reconstruction literature is presented in combination with a historic overview of cardiac CT imaging and a brief introduction to other cardiac imaging modalities. The thesis includes a comprehensive chapter about the theory of CT reconstruction, familiarizing the reader with the problem of cone-beam reconstruction. The anatomic and dynamic properties of the heart are outlined and techniques to derive the gating information are reviewed. With the extended cardiac reconstruction (ECR) framework, a new approach is presented for the heart-rate-adaptive gated helical cardiac cone-beam CT reconstruction. Reconstruction assessment criteria such as the temporal resolution, the homogeneity in terms of the cardiac phase, and the smoothness at cycle-to-cycle transitions are developed. Several reconstruction optimization approaches are described: An approach for the heart-rate-adaptive optimization of the temporal resolution is presented. Streak artifacts at cycle-to-cycle transitions can be minimized by using an improved cardiac weighting scheme. The optimal quiescent cardiac phase for the reconstruction can be determined automatically with the motion map technique. Results for all optimization procedures applied to ECR are presented and discussed based on patient and phantom data. The ECR algorithm is analyzed for larger detector arrays of future cone-beam systems throughout an extensive simulation study based on a four-dimensional cardiac CT phantom. The results of the scientific work are summarized and an outlook proposing future directions is given. The presented thesis is available for public download at www.cardiac-ct.net.

  20. CT Imaging: Basics and New Trends

    NASA Astrophysics Data System (ADS)

    Peyrin, Françoise; Engelke, Klaus

    This chapter presents the principle of X-ray CT and its evolution during the last 40 years. The first section describes the physical basis of X-ray CT, tomographic image reconstruction algorithms, and the source of artifacts in X-ray CT images. The second section is devoted to the evolution of CT technology from the first translation-rotation systems to multi-slice spiral CTs currently used today. The next section addresses specific developments of CT technology and applications, like perfusion CT, quantitative CT, and spectral CT. The fourth section introduces the problem of radiation exposure delivered to the patient and its evaluation. Finally the last section addresses the development in micro- and even nano-CT which is a rapidly evolving area in preclinical imaging and biology.

  1. New horizons in cardiac CT.

    PubMed

    den Harder, A M; Willemink, M J; de Jong, P A; Schilham, A M R; Rajiah, P; Takx, R A P; Leiner, T

    2016-08-01

    Until recently, cardiovascular computed tomography angiography (CCTA) was associated with considerable radiation doses. The introduction of tube current modulation and automatic tube potential selection as well as high-pitch prospective ECG-triggering and iterative reconstruction offer the ability to decrease dose with approximately one order of magnitude, often to sub-millisievert dose levels. In parallel, advancements in computational technology have enabled the measurement of fractional flow reserve (FFR) from CCTA data (FFRCT). This technique shows potential to replace invasively measured FFR to select patients in need of coronary intervention. Furthermore, developments in scanner hardware have led to the introduction of dual-energy and photon-counting CT, which offer the possibility of material decomposition imaging. Dual-energy CT reduces beam hardening, which enables CCTA in patients with a high calcium burden and more robust myocardial CT perfusion imaging. Future-generation CT systems will be capable of counting individual X-ray photons. Photon-counting CT is promising and may result in a substantial further radiation dose reduction, vastly increased spatial resolution, and the introduction of a whole new class of contrast agents. PMID:26932775

  2. Renal applications of dual-energy CT.

    PubMed

    Kaza, Ravi K; Platt, Joel F

    2016-06-01

    Dual-energy CT is being increasingly used for abdominal imaging due to its incremental benefit of material characterization without significant increase in radiation dose. Knowledge of the different dual-energy CT acquisition techniques and image processing algorithms is essential to optimize imaging protocols and understand potential limitations while using dual-energy CT renal imaging such as urinary calculi characterization, assessment of renal masses and in CT urography. This review article provides an overview of the current dual-energy CT techniques and use of dual-energy CT in renal imaging. PMID:27010938

  3. Malignant external otitis: CT evaluation

    SciTech Connect

    Curtin, H.D.; Wolfe, P.; May, M.

    1982-11-01

    Malignant external otitis is an aggressive infection caused by Pseudomonas aeruginosa that most often occurs in elderly diabetics. Malignant external otitis often spreads inferiorly from the external canal to involve the subtemporal area and progresses medially towards the petrous apex leading to multiple cranial nerve palsies. The computed tomographic (CT) findings in malignant external otitis include obliteration of the normal fat planes in the subtemporal area as well as patchy destruction of the bony cortex of the mastoid. The point of exit of the various cranial nerves can be identified on CT scans, and the extent of the inflammatory mass correlates well with the clinical findings. Four cases of malignant external otitis are presented. In each case CT provided a good demonstration of involvement of the soft tissues at the base of the skull.

  4. CT of the gluteal region

    SciTech Connect

    Wechsler, R.J.; Schilling, J.F.

    1985-01-01

    Although the buttock can be involved in many pathologic processes, most physicians pay little attention to this area of the body. Because pelvic computed tomography (CT) delineates gluteal anatomy exquisitely, pathologic processes in the buttock are now frequently seen. Inflammation, neoplasm, or trauma involving the buttock may be difficult to differentiate without clinical history. However, spread of these processes to or from the pelvis or retroperitoneum is easily documented by CT. A number of these pathologic processes and the pathways of spread of disease involving the pelvis or retroperitoneum are described in this review.

  5. In Defense of Body CT

    PubMed Central

    McCollough, Cynthia H.; Guimarães, Luís; Fletcher, Joel G.

    2009-01-01

    Rapid technical developments, and an expanding list of applications that have supplanted less accurate or more invasive diagnostic tests, have led to a dramatic increase in the use of body CT imaging in medical practice since its introduction in 1975. Our purpose here is to discuss medical justification of the small risk associated with the ionizing radiation used in CT and to provide perspectives on practice-specific decisions that can maximize overall patient benefit. In addition, we review available dose management and optimization technique. PMID:19542392

  6. PET/CT in radiation oncology

    SciTech Connect

    Pan, Tinsu; Mawlawi, Osama

    2008-11-15

    PET/CT is an effective tool for the diagnosis, staging and restaging of cancer patients. It combines the complementary information of functional PET images and anatomical CT images in one imaging session. Conventional stand-alone PET has been replaced by PET/CT for improved patient comfort, patient throughput, and most importantly the proven clinical outcome of PET/CT over that of PET and that of separate PET and CT. There are over two thousand PET/CT scanners installed worldwide since 2001. Oncology is the main application for PET/CT. Fluorine-18 deoxyglucose is the choice of radiopharmaceutical in PET for imaging the glucose uptake in tissues, correlated with an increased rate of glycolysis in many tumor cells. New molecular targeted agents are being developed to improve the accuracy of targeting different disease states and assessing therapeutic response. Over 50% of cancer patients receive radiation therapy (RT) in the course of their disease treatment. Clinical data have demonstrated that the information provided by PET/CT often changes patient management of the patient and/or modifies the RT plan from conventional CT simulation. The application of PET/CT in RT is growing and will become increasingly important. Continuing improvement of PET/CT instrumentation will also make it easier for radiation oncologists to integrate PET/CT in RT. The purpose of this article is to provide a review of the current PET/CT technology, to project the future development of PET and CT for PET/CT, and to discuss some issues in adopting PET/CT in RT and potential improvements in PET/CT simulation of the thorax in radiation therapy.

  7. Low-dose interpolated average CT for attenuation correction in cardiac PET/CT

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    Because of the advantages in the use of high photon flux and thus the short scan times of CT imaging, the traditional 68Ge scans for positron emission tomography (PET) image attenuation correction have been replaced by CT scans in the modern PET/CT technology. The combination of fast CT scan and slow PET scan often causes image misalignment between the PET and CT images due to respiration motion. Use of the average CT derived from cine CT images is reported to reduce such misalignment. However, the radiation dose to patients is higher with cine CT scans. This study introduces a method that uses breath-hold CT images and their interpolations to generate the average CT for PET image attenuation correction. Breath-hold CT sets are taken at end-inspiration and end-expiration. Deformable image registration is applied to generate a voxel-to-voxel motion matrix between the two CT sets. The motion is equally divided into 5 steps from inspiration to expiration and 5 steps from expiration to inspiration, generating a total of 8 phases of interpolated CT sets. An average CT image is generated from all the 10 phase CT images, including original inhale/exhale CT and 8 interpolated CT sets. Quantitative comparison shows that the reduction of image misalignment artifacts using the average CT from the interpolation technique for PET attenuation correction is at a similar level as that using cine average CT, while the dose to the patient from the CT scans is reduced significantly. The interpolated average CT method hence provides a low dose alternative to cine CT scans for PET attenuation correction.

  8. Pocket atlas of normal CT anatomy

    SciTech Connect

    Weinstein, J.B.; Lee, J.K.T.; Sagel, S.S.

    1985-01-01

    This book is a quick reference for interpreting CT scans of the extracranial organs. This collection of 41 CT scans covers all the major organs of the body: neck and larynx; chest; abdomen; male pelvis; and female pelvis.

  9. Cardiac Computed Tomography (Multidetector CT, or MDCT)

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Cardiac Computed Tomography (Multidetector CT, or MDCT) Updated:Sep 3,2015 ... facts MDCT is a very fast type of computed tomography (CT) scan. MDCT creates pictures of the healthy ...

  10. [CT diagnosis of coal workers' pneumoconiosis].

    PubMed

    Pan, J S

    1989-02-01

    In order to evaluate the usefulness of CT in CWP, 100 coal workers were examined with both chest radiograph and CT scan. Comparison was done, the result indicated that both modalities yielded similar sensitivity to simple CWP. The CT score of simple CWP correlated well with ILO classification and 1986 Chinese criteria for staging of pneumoconiosis, whereas in complicated CWP, the CT scan was significantly superior to chest radiograph. CT scan identified readily large opacities. It could detect large opacities in 40% of simple CWP diagnosed on the basis of chest radiograph. CT scan also identified more cavities and calcifications within large opacities. The CT attenuation values were less reliable. The authors were of the opinion that at present CT attenuation values is not recommended for routine evaluation of CWP. PMID:2758921

  11. Acute pancreatitis: clinical vs. CT findings

    SciTech Connect

    Hill, M.C.; Barkin, J.; Isikoff, M.B.; Silver stein, W.; Kalser, M.

    1982-08-01

    In a prospective study of 91 patients with acute pancreatitis, computed tomographic (CT) findings were correlated with the clinical type of acute pancreatitis. In acute edematous pancreatitis (63 patients; 16 with repeat CT), CT was normal (28%) or showed inflammation limited to the pancreas (61%). Phlegmonous changes were present in 11%, including one patient with focal pancreatic hemorrhage, indicating that clinically unsuspected hemorrhagic pancreatitis can occur. In acute necrotizing (hemorrhagic, suppurative) pancreatitis (nine patients; eight with repeat CT), no patient had a normal CT scan and 89% had phlegmonous changes. One patient had hemorrhagic pancreatitis and three had abscesses. In acute exacerbation of chronic pancreatitis (10 patients; three with repeat CT), there were pancreatic calcifications (70%), a focal mass (40%), and pancreatic ductal dilation (30%). On follow-up CT, the findings of acute pancreatitis did not always disappear with resolution of the clinical symptons. This was especialy true of phlegmonous pancreatitis, where the CT findings could persist for months.

  12. The evolution of PET-CT.

    PubMed

    Wilson, Bettye G

    2005-01-01

    Positron emission tomography-computed tomography (PET-CT) was the first fused or combined medical imaging technique. Although PET-CT has received widespread acclaim as a major imaging advancement, many questions have surfaced regarding its use. This article answers some of these questions and examines what PET-CT means to medicine and the medical imaging community. PMID:15835615

  13. Calibrator Blocks For Computerized Tomography (CT)

    NASA Technical Reports Server (NTRS)

    Engel, H. Peter

    1990-01-01

    Sets of calibrator blocks developed for use with industrial computerized tomography (CT) systems. Set of blocks (or number of stacked sets of blocks) placed on object table of CT system and scanned in usual way. Blocks include holes of known size, shape, and location. Appearance of holes in output image of CT system used to verify operation of system.

  14. Micro-CT as a guide for clinical CT development

    NASA Astrophysics Data System (ADS)

    Ritman, Erik L.; Eaker, Diane R.; Jorgensen, Steven M.

    2006-08-01

    Micro-CT, with voxel size ~10 -5 mm 3, has a great advantage over traditional microscopic methods in its ability to generate detailed 3D images in relatively large, opaque, volumes such as an intact mouse femur, heart or kidney. In addition to providing new insights into tissue structure-to-function interrelationships, micro-CT can contribute to suggesting new applications of clinical CT imaging such as: A. The spatio-density-temporal resolution that is needed to: 1) Quantitate an organ's Basic Functional Unit (smallest collection of diverse cells that behaves like the organ), which requires voxels less than 10 -4 mm 3 in volume; 2) Quantitate new vessel growth which manifests as increased x-ray contrast enhancement in tissues during passage of a bolus of intravascular contrast agent; 3) Quantitate endothelial integrity by the movement of x-ray contrast agents across the endothelial inner lining of vessel walls. B. The use of x-ray scatter for providing the contrast amongst soft tissue components and/or their interfaces for enhanced discrimination of nerve and muscular/tendon fiber directions.

  15. Ultra-low dose CT attenuation correction for PET/CT

    NASA Astrophysics Data System (ADS)

    Xia, Ting; Alessio, Adam M.; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren; Kinahan, Paul E.

    2012-01-01

    A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging.

  16. CT colonography: techniques, indications, findings.

    PubMed

    Mang, Thomas; Graser, Anno; Schima, Wolfgang; Maier, Andrea

    2007-03-01

    Computed tomographic colonography (CTC) is a minimally invasive technique for imaging the entire colon. Based on a helical thin-section CT of the cleansed and air-distended colon, two-dimensional and three-dimensional projections are used for image interpretation. Several clinical improvements in patient preparation, technical advances in CT, and new developments in evaluation software have allowed CTC to develop into a powerful diagnostic tool. It is already well established as a reliable diagnostic tool in symptomatic patients. Many experts currently consider CTC a comparable alternative to conventional colonoscopy, although there is still debate about its sensitivity for the detection of colonic polyps in a screening population. This article summarizes the main indications, the current techniques in patient preparation, data acquisition and data analysis as well as imaging features for common benign and malignant colorectal lesions. PMID:17224254

  17. Dual energy CT for attenuation correction with PET/CT

    SciTech Connect

    Xia, Ting; Alessio, Adam M.; Kinahan, Paul E.

    2014-01-15

    Purpose: The authors evaluate the energy dependent noise and bias properties of monoenergetic images synthesized from dual-energy CT (DECT) acquisitions. These monoenergetic images can be used to estimate attenuation coefficients at energies suitable for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging. This is becoming more relevant with the increased use of quantitative imaging by PET/CT and SPECT/CT scanners. There are, however, potential variations in the noise and bias of synthesized monoenergetic images as a function of energy. Methods: The authors used analytic approximations and simulations to estimate the noise and bias of synthesized monoenergetic images of water-filled cylinders with different shapes and the NURBS-based cardiac-torso (NCAT) phantom from 40 to 520 keV, the range of SPECT and PET energies. The dual-kVp spectra were based on the GE Lightspeed VCT scanner at 80 and 140 kVp with added filtration of 0.5 mm Cu. The authors evaluated strategies of noise suppression with sinogram smoothing and dose minimization with reduction of tube currents at the two kVp settings. The authors compared the impact of DECT-based attenuation correction with single-kVp CT-based attenuation correction on PET quantitation for the NCAT phantom for soft tissue and high-Z materials of bone and iodine contrast enhancement. Results: Both analytic calculations and simulations displayed the expected minimum noise value for a synthesized monoenergetic image at an energy between the mean energies of the two spectra. In addition the authors found that the normalized coefficient of variation in the synthesized attenuation map increased with energy but reached a plateau near 160 keV, and then remained constant with increasing energy up to 511 keV and beyond. The bias was minimal, as the linear attenuation coefficients of the synthesized monoenergetic images were within 2.4% of the known true values across the entire energy range

  18. CT-assisted agile manufacturing

    NASA Astrophysics Data System (ADS)

    Stanley, James H.; Yancey, Robert N.

    1996-11-01

    The next century will witness at least two great revolutions in the way goods are produced. First, workers will use the medium of virtual reality in all aspects of marketing, research, development, prototyping, manufacturing, sales and service. Second, market forces will drive manufacturing towards small-lot production and just-in-time delivery. Already, we can discern the merging of these megatrends into what some are calling agile manufacturing. Under this new paradigm, parts and processes will be designed and engineered within the mind of a computer, tooled and manufactured by the offspring of today's rapid prototyping equipment, and evaluated for performance and reliability by advanced nondestructive evaluation (NDE) techniques and sophisticated computational models. Computed tomography (CT) is the premier example of an NDE method suitable for future agile manufacturing activities. It is the only modality that provides convenient access to the full suite of engineering data that users will need to avail themselves of computer- aided design, computer-aided manufacturing, and computer- aided engineering capabilities, as well as newly emerging reverse engineering, rapid prototyping and solid freeform fabrication technologies. As such, CT is assured a central, utilitarian role in future industrial operations. An overview of this exciting future for industrial CT is presented.

  19. Modern CT applications in veterinary medicine.

    PubMed

    Garland, Melissa R; Lawler, Leo P; Whitaker, Brent R; Walker, Ian D F; Corl, Frank M; Fishman, Elliot K

    2002-01-01

    Although computed tomography (CT) is used primarily for diagnosis in humans, it can also be used to diagnose disease in veterinary patients. CT and associated three-dimensional reconstruction have a role in diagnosis of a range of illnesses in a variety of animals. In a sea turtle with failure to thrive, CT showed a nodal mass in the chest, granulomas in the lungs, and a ball in the stomach. CT of a sea dragon with balance and movement problems showed absence of the swim bladder. In a sloth with failure to thrive, CT allowed diagnosis of a coin in the intestine. CT of a puffin with failure to thrive showed a mass in the chest, which was found to be a hematoma. In a smooth-sided toad whose head was tilted to one side and who was circling in that direction, CT showed partial destruction of the temporal bone. CT of a domestic cat with listlessness showed a mass with focal calcification, which proved to be a leiomyosarcoma. CT of a sea otter showed pectus excavatum, which is caused by the animal smashing oysters against its chest. In a Japanese koi with abdominal swelling, CT allowed diagnosis of a hepatoma. PMID:11796898

  20. MRI, enhanced CT, and FDG PET/CT in primary retroperitoneal mucinous cystadenocarcinoma.

    PubMed

    Dong, Aisheng; Zhai, Zhijun; Wang, Yang; Zuo, Changjing

    2015-01-01

    Primary retroperitoneal mucinous cystadenocarcinoma (PRMC) is an extremely rare neoplasm. We present a case of PRMC with MRI, enhanced CT, and FDG PET/CT findings. Abdominal MRI showed a cystic lesion in the retroperitoneum with a mural nodule. The mural nodule showed progressive enhancement on enhanced CT and intense FDG uptake on early PET/CT with increased SUVmax on delayed PET/CT. Laparoscopy was performed. Retroperitoneal mucinous cystadenocarcinoma was confirmed histopathologically. Metastasis from gastrointestinal tract or ovary was excluded. This case indicates, although rare, PRMC should be considered when a hypermetabolic retroperitoneal cystic lesion with bilateral normal ovaries is found on FDG PET/CT. PMID:24445275

  1. Optical-CT scanning of polymer gels

    PubMed Central

    Oldham, M

    2006-01-01

    The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data. PMID:17082823

  2. Gastric interposition following transhiatal esophagectomy: CT evaluation

    SciTech Connect

    Gross, B.H.; Agha, F.P.; Glazer, G.M.; Orringer, M.B.

    1985-04-01

    Transhiatal esophagectomy without thoracotomy (THE) but with gastric interposition results in less morbidity and mortality than standard transpleural esophagectomy with thoracotomy. Barium examination has been the primary radiographic study following THE for detecting postoperative complications. The authors reviewed computed tomography (CT) scans of 21 patients who had undergone THE and correlated CT appearance with clinical status and with findings of the barium studies. Local mediastinal recurrent neoplasm was detected by CT in seven patients; barium study within 2 weeks of the CT scan failed to detect tumor recurrence in three of these patients. CT is the modality of choice for detecting locally recurrent neoplasm and distant metastases following THE and may also be helpful in patients with postoperative mediastinal abscess. Normal mediastinal CT anatomy after esophagectomy is reviewed in order to warn against pitfalls in scan interpretation.

  3. Intracranial vascular malformations: MR and CT imaging

    SciTech Connect

    Kucharczyk, W.; Lemme-Pleghos, L.; Uske, A.; Brant-Zawadzki, M.; Dooms, G.; Norman, D.

    1985-08-01

    Twenty-four patients with 29 cerebrovascular malformations were evaluated with a combination of computed tomography (CT), angiography, and magnetic resonance (MR) imaging. Characteristics of the malformations on MR images were reviewed retrospectively, and a comparative evaluation of MR and CT images was made. Of 14 angiographically evident malformations, 13 intra-axial lesions were detected on both CT and MR images, and one dural malformation gave false-negative results on both modalities. The appearance of parenchymal lesions on MR images closely mirrored characteristic CT findings. Angiographically evident malformations have a highly characteristic appearance on MR images. MR may be more sensitive than CT in the detection of small hemorrhagic foci associated with cryptic arteriovenous malformations and may add specificity in the diagnosis of occult malformations in some cases, but MR is less sensitive than CT for the detection of small calcified malformations.

  4. Cortical Tremor (CT) with coincident orthostatic movements.

    PubMed

    Termsarasab, Pichet; Frucht, Steven J

    2015-01-01

    Cortical tremor (CT) is a form of cortical reflex myoclonus that can mimic essential tremor (ET). Clinical features that are helpful in distinguishing CT from ET are the irregular and jerky appearance of the movements. We report two patients with CT with coexisting orthostatic movements, either orthostatic tremor (OT) or myoclonus, who experienced functional improvement in both cortical myoclonus and orthostatic movements when treated with levetiracetam. PMID:26788343

  5. Radiation dose measurements in coronary CT angiography

    PubMed Central

    Sabarudin, Akmal; Sun, Zhonghua

    2013-01-01

    Coronary computed tomography (CT) angiography is associated with high radiation dose and this has raised serious concerns in the literature. Awareness of various parameters for dose estimates and measurements of coronary CT angiography plays an important role in increasing our understanding of the radiation exposure to patients, thus, contributing to the implementation of dose-saving strategies. This article provides an overview of the radiation dose quantity and its measurement during coronary CT angiography procedures. PMID:24392190

  6. Helical 4D CT and Comparison with Cine 4D CT

    NASA Astrophysics Data System (ADS)

    Pan, Tinsu

    4D CT was one of the most important developments in radiation oncology in the last decade. Its early development in single slice CT and commercialization in multi-slice CT has radically changed our practice in radiation treatment of lung cancer, and has enabled the stereotactic radiosurgery of early stage lung cancer. In this chapter, we will document the history of 4D CT development, detail the data sufficiency condition governing the 4D CT data collection; present the design of the commercial helical 4D CTs from Philips and Siemens; compare the differences between the helical 4D CT and the GE cine 4D CT in data acquisition, slice thickness, acquisition time and work flow; review the respiratory monitoring devices; and understand the causes of image artifacts in 4D CT.

  7. Laxative-free CT colonography

    PubMed Central

    Slater, A; Betts, M; D'Costa, H

    2012-01-01

    Objectives The aim of this study was to determine if the introduction of faecal tagging to CT colonography (CTC) made the examination easier to tolerate or reduced the number of false-positives. Methods Our department changed bowel preparation for CT colonography from Picolax (Ferring Pharmaceuticals Ltd, London, UK) to Gastrografin® (Bracco Diagnostics Inc, Princeton, NJ) only with a modified diet. Questionnaires were given to a subgroup of patients within these cohorts. The numbers of false-positives were compared between two cohorts before and after this change. false-positives were defined as lesions reported on CT that were not confirmed by subsequent endoscopic examination. Polyps were matched if they were in the same or adjacent segments, and were within 5 mm of the reported size. Results 412 patients were identified from the Picolax cohort, and 116 from the Gastrografin cohort. 62 patients in each group completed questionnaires. Gastrografin produced less diarrhoea; 34% had five or more bowel motions in the previous day and night, compared with 77% for Picolax (p<0.001), although more patients found drinking it unpleasant compared with Picolax (85% reported drinking Picolax as “easy” vs 61% for Gastrografin; p=0.002). Picolax produced more non-diagnostic examinations, although this difference was not statistically significant. There was not a significant reduction in the numbers of false-positives (2 out of 112 for Gastrografin group, 14 out of 389 for the Picolax group; p=0.54). Conclusion Switching from Picolax to Gastrografin as a CTC preparation technique produced less diarrhoea, but did not reduce the number of false-positives. PMID:22167512

  8. An outlook on x-ray CT research and development.

    PubMed

    Wang, Ge; Yu, Hengyong; De Man, Bruno

    2008-03-01

    Over the past decade, computed tomography (CT) theory, techniques and applications have undergone a rapid development. Since CT is so practical and useful, undoubtedly CT technology will continue advancing biomedical and non-biomedical applications. In this outlook article, we share our opinions on the research and development in this field, emphasizing 12 topics we expect to be critical in the next decade: analytic reconstruction, iterative reconstruction, local/interior reconstruction, flat-panel based CT, dual-source CT, multi-source CT, novel scanning modes, energy-sensitive CT, nano-CT, artifact reduction, modality fusion, and phase-contrast CT. We also sketch several representative biomedical applications. PMID:18404940

  9. SPECT/CT and pulmonary embolism.

    PubMed

    Mortensen, Jann; Gutte, Henrik

    2014-05-01

    Acute pulmonary embolism (PE) is diagnosed either by ventilation/perfusion (V/P) scintigraphy or pulmonary CT angiography (CTPA). In recent years both techniques have improved. Many nuclear medicine centres have adopted the single photon emission CT (SPECT) technique as opposed to the planar technique for diagnosing PE. SPECT has been shown to have fewer indeterminate results and a higher diagnostic value. The latest improvement is the combination of a low-dose CT scan with a V/P SPECT scan in a hybrid tomograph. In a study comparing CTPA, planar scintigraphy and SPECT alone, SPECT/CT had the best diagnostic accuracy for PE. In addition, recent developments in the CTPA technique have made it possible to image the pulmonary arteries of the lungs in one breath-hold. This development is based on the change from a single-detector to multidetector CT technology with an increase in volume coverage per rotation and faster rotation. Furthermore, the dual energy CT technique is a promising modality that can provide functional imaging in combination with anatomical information. Newer high-end CT scanners and SPECT systems are able to visualize smaller subsegmental emboli. However, consensus is lacking regarding the clinical impact and treatment. In the present review, SPECT and SPECT in combination with low-dose CT, CTPA and dual energy CT are discussed in the context of diagnosing PE. PMID:24213621

  10. [Development of real-time CT fluoroscopy].

    PubMed

    Katada, K; Anno, H; Takeshita, G; Ogura, Y; Koga, S; Ida, Y; Nonomura, K; Kanno, T; Ohashi, A; Sata, S

    1994-10-25

    A new CT system that permits real-time monitoring of CT images was developed. Phantom and volunteer studies revealed that the images were displayed at a rate of six per second with a delay time of 0.83 second with clinically sufficient resolution (256 x 256) using the newly developed fast image processor and partial-reconstruction algorithm. The clinical trial of stereotactic aspiration of intracerebral hematoma was successful. The initial trial with CT fluoroscopy revealed potential usefulness of the system in biopsy and other CT-guided interventions. PMID:9261196

  11. Transsphenoidal hypophysectomy: postsurgical CT findings

    SciTech Connect

    Dolinskas, C.A.; Simeone, F.A.

    1985-03-01

    Transsphenoidal surgery produces changes in the paranasal sinuses and sella that should be familiar to radiologists in view of frequency of this type of surgery. Some of these changes, such as soft-tissue-density debris in the sinuses, are transient. Fat and other packing material identifiable in the sinuses and sella after surgery is permanent. The procedure is associated with a variety of complications that are readily detectable by computed tomography (CT). These include bleeding, compression of parasellar structures by packing material, cerebrospinal fluid leaks, and pneumocephalus. After a transsphenoidal procedure, with or without follow-up radiation therapy, residual enhancing intrasellar and parasellar lesions may still be identified.

  12. Synchronous navigation for CT colonography

    NASA Astrophysics Data System (ADS)

    Huang, Adam; Summers, Ronald M.; Roy, Dave

    2006-03-01

    We present a synchronous navigation module for CT colonography (CTC) reading. The need for such a system arises because most CTC protocols require a patient to be scanned in both supine and prone positions to increase sensitivity in detecting colonic polyps. However, existing clinical practices are limited to reading one scan at a time. Such limitation is due to the fact that building a reference system between scans for the highly flexible colon is a nontrivial task. The conventional centerline approach, generating only the longitudinal distance along the colon, falls short in providing the necessary orientation information to synchronize the virtual navigation cameras in both scanned positions. In this paper we describe a synchronous navigation system by using the teniae coli as anatomical references. Teniae coli are three parallel bands of longitudinal smooth muscle on the surface of the colon. They are morphologically distinguishable and form a piecewise triple helix structure from the appendix to the sigmoid colon. Because of these characteristics, they are ideal references to synchronize virtual cameras in both scanned positions. Our new navigation system consists of two side-by-side virtual colonoscopic view panels (for the supine and prone data sets respectively) and one single camera control unit (which controls both the supine and prone virtual cameras). The capability to examine the same colonic region simultaneously in both scanned images can raise an observer's confidence in polyp identification and potentially improve the performance of CT colonography.

  13. Intracranial CT angiography obtained from a cerebral CT perfusion examination

    SciTech Connect

    Gratama van Andel, H. A. F.; Venema, H. W.; Majoie, C. B.; Den Heeten, G. J.; Grimbergen, C. A.; Streekstra, G. J.

    2009-04-15

    CT perfusion (CTP) examinations of the brain are performed increasingly for the evaluation of cerebral blood flow in patients with stroke and vasospasm after subarachnoid hemorrhage. Of the same patient often also a CT angiography (CTA) examination is performed. This study investigates the possibility to obtain CTA images from the CTP examination, thereby possibly obviating the CTA examination. This would save the patient exposure to radiation, contrast, and time. Each CTP frame is a CTA image with a varying amount of contrast enhancement and with high noise. To improve the contrast-to-noise ratio (CNR) we combined all 3D images into one 3D image after registration to correct for patient motion between time frames. Image combination consists of weighted averaging in which the weighting factor of each frame is proportional to the arterial contrast. It can be shown that the arterial CNR is maximized in this procedure. An additional advantage of the use of the time series of CTP images is that automatic differentiation between arteries and veins is possible. This feature was used to mask veins in the resulting 3D images to enhance visibility of arteries in maximum intensity projection (MIP) images. With a Philips Brilliance 64 CT scanner (64x0.625 mm) CTP examinations of eight patients were performed on 80 mm of brain using the toggling table technique. The CTP examination consisted of a time series of 15 3D images (2x64x0.625 mm; 80 kV; 150 mAs each) with an interval of 4 s. The authors measured the CNR in images obtained with weighted averaging, images obtained with plain averaging, and images with maximal arterial enhancement. The authors also compared CNR and quality of the images with that of regular CTA examinations and examined the effectiveness of automatic vein masking in MIP images. The CNR of the weighted averaged images is, on the average, 1.73 times the CNR of an image at maximal arterial enhancement in the CTP series, where the use of plain averaging

  14. 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.

  15. State-of-the-art in CT hardware and scan modes for cardiovascular CT

    PubMed Central

    Halliburton, Sandra; Arbab-Zadeh, Armin; Dey, Damini; Einstein, Andrew J.; Gentry, Ralph; George, Richard T.; Gerber, Thomas; Mahesh, Mahadevappa; Weigold, Wm. Guy

    2013-01-01

    Multidetector row computed tomography (CT) allows noninvasive anatomic and functional imaging of the heart, great vessels, and the coronary arteries. In recent years, there have been several advances in CT hardware, which have expanded the clinical utility of CT for cardiovascular imaging; such advances are ongoing. This review article from the Society of Cardiovascular Computed Tomography (SCCT) Basic and Emerging Sciences and Technology (BEST) Working Group summarizes the technical aspects of current state-of-the-art CT hardware and describes the scan modes this hardware supports for cardiovascular CT imaging. PMID:22551595

  16. CT demonstration of bilateral adrenal hemorrhage

    SciTech Connect

    Ling, D.; Korobkin, M.; Silverman, P.M.; Dunnick, N.R.

    1983-08-01

    Bilateral adrenal hemorrhage with subsequent adrenal insufficiency is a recognized complication of anticoagulant therapy. Because the clinical manifestations are often nonspecific, the antemortem diagnosis of adrenal hemorrhage has been a difficult clinical problem. Computed tomography (CT) provides detailed images of the adrenal glands that are not possible with conventional imaging methods. The CT findings of bilateral adrenal hemorrhage in an anticoagulated patient are reported.

  17. CT of schistosomal calcification of the intestine

    SciTech Connect

    Fataar, S.; Bassiony, H.; Satyanath, S.; Rudwan, M.; Hebbar, G.; Khalifa, A.; Cherian, M.J.

    1985-01-01

    The spectrum of schistosomal colonic calcification on abdominal radiographs has been described. The appearance on computed tomography (CT) is equally distinctive and occurs with varying degrees of genitourinary calcification. The authors have experience in three cases with the appearance on CT of intestinal calcification due to schistosomiasis.

  18. Multiparametric PET/CT in oncology

    PubMed Central

    Miles, Kenneth

    2012-01-01

    Abstract The standardized uptake value (SUV) and other measurements of tumour uptake of fluorodeoxyglucose (FDG) on positron emission tomography (PET) can potentially be supplemented by additional imaging parameters derived either from the PET images or from the computed tomography (CT) component of integrated PET/CT examinations including tumour size, CT attenuation, texture (reflecting tumour heterogeneity) and blood flow. This article illustrates the emerging benefits of such a multiparametric approach. Example benefits include greater diagnostic accuracy in characterization of adrenal masses achieved by using both the SUV and measured CT attenuation. Tumour size combined with the SUV can potentially improve the prognostic information available from PET/CT in oesophageal and lung cancer. However, greater improvements may be realized through using CT measurements of texture instead of size. Studies in breast and lung cancer suggest that combined PET/CT measurements of glucose metabolism and blood flow provide correlates for tumour proliferation and angiogenesis, respectively. These combined measurements can be utilized to determine vascular-metabolic phenotypes, which vary with tumour type. Uncoupling of blood flow and metabolism suggests a poor prognosis for larger more advanced tumours, high-grade lesions and tumours responding poorly to treatment. Vascular-metabolic imaging also has the potential to subclassify tumour response to treatment. The additional biomarkers described can be readily incorporated in existing FDG-PET examinations thereby improving the ability of PET/CT to depict tumour biology, characterize potentially malignant lesions, and assess prognosis and therapeutic response. PMID:23023069

  19. CT demonstration of an aortoesophageal fistula.

    PubMed

    Longo, J M; Lopez-Rasines, G; Ortega, E; Pagola, M A

    1987-01-01

    A case of aortoesophageal fistula (AEF) is reported in a patient with esophageal bleeding resulting from ingestion of a foreign body. CT showed a saccular aneurysm in close proximity to the esophageal lumen at the level of the bleeding site. AEF has not previously been described on CT. PMID:3107831

  20. A Wiki Based CT Protocol Management System.

    PubMed

    Szczykutowicz, Timothy P; Rubert, Nicholas; Belden, Daryn; Ciano, Amanda; Duplissis, Andrew; Hermanns, Ashley; Monette, Stephen; Saldivar, Elliott Janssen

    2015-01-01

    At the University of Wisconsin Madison Department of Radiology, CT protocol management requires maintenance of thousands of parameters for each scanner. Managing CT protocols is further complicated by the unique configurability of each scanner. Due to recent Joint Commission requirements, now all CT protocol changes must be documented and reviewed by a site's CT protocol optimization team. The difficulty of managing the CT protocols was not in assembling the protocols, but in managing and implementing changes. This is why a wiki based solution for protocol management was implemented. A wiki inherently keeps track of all changes, logging who made the changes and when, allowing for editing and viewing permissions to be controlled, as well as allowing protocol changes to be instantly relayed to all scanner locations. PMID:26710573

  1. Artifacts in CT: recognition and avoidance.

    PubMed

    Barrett, Julia F; Keat, Nicholas

    2004-01-01

    Artifacts can seriously degrade the quality of computed tomographic (CT) images, sometimes to the point of making them diagnostically unusable. To optimize image quality, it is necessary to understand why artifacts occur and how they can be prevented or suppressed. CT artifacts originate from a range of sources. Physics-based artifacts result from the physical processes involved in the acquisition of CT data. Patient-based artifacts are caused by such factors as patient movement or the presence of metallic materials in or on the patient. Scanner-based artifacts result from imperfections in scanner function. Helical and multisection technique artifacts are produced by the image reconstruction process. Design features incorporated into modern CT scanners minimize some types of artifacts, and some can be partially corrected by the scanner software. However, in many instances, careful patient positioning and optimum selection of scanning parameters are the most important factors in avoiding CT artifacts. PMID:15537976

  2. CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice

    PubMed Central

    Al Moudi, Mansour; Cao, Yan

    2014-01-01

    Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice. PMID:25392823

  3. CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice.

    PubMed

    Sun, Zhonghua; Al Moudi, Mansour; Cao, Yan

    2014-10-01

    Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice. PMID:25392823

  4. Cardiac CT Imaging of Plaque Vulnerability: Hype or Hope?

    PubMed

    Willemink, Martin J; Leiner, Tim; Maurovich-Horvat, Pál

    2016-03-01

    Advances in cardiovascular computed tomography (CT) have resulted in an excellent ability to exclude coronary heart disease (CHD). Anatomical information, functional information, and spectral information can already be obtained with current CT technologies. Moreover, novel developments such as targeted nanoparticle contrast agents, photon-counting CT, and phase contrast CT will further enhance the diagnostic value of cardiovascular CT. This review provides an overview of current state of the art and future cardiovascular CT imaging. PMID:26922591

  5. SLATE: Virtualizing multiscale CT training

    PubMed Central

    Mishra, Sourav; Sharma, Kriti Sen; Lee, Spencer J.; Fox, Edward A.; Wang, Ge

    2014-01-01

    Training on micro- and nano- computed tomography (CT) scanners has been traditionally conducted via extensive practice on the instrument. This entails presence of an instructor to guide through the training procedure, until reasonable experience is attained. Modern tomographic instruments being expensive to maintain, the operational costs escalates with increasing number of training conducted. In a pioneering approach, the technical know-how to operate such equipment has been partly imparted via virtual reality environment running on the Second Life grid. The experimentation has indicated a reduction of the total training time. The authors hope that in the long run, such techniques will aid in significant reduction of instruction time and costs associated with training. PMID:22635178

  6. Physiologic evaluation of ischemia using cardiac CT: current status of CT myocardial perfusion and CT fractional flow reserve.

    PubMed

    Choi, Andrew D; Joly, Joanna M; Chen, Marcus Y; Weigold, Wm Guy

    2014-01-01

    Cardiac CT, specifically coronary CT angiography (CTA), is an established technology which detects anatomically significant coronary artery disease with a high sensitivity and negative predictive value compared with invasive coronary angiography. However, the limited ability of CTA to determine the physiologic significance of intermediate coronary stenoses remains a shortcoming compared with other noninvasive methods such as single-photon emission CT, stress echocardiography, and stress cardiac magnetic resonance. Two methods have been investigated recently: (1) myocardial CT perfusion and (2) fractional flow reserve (FFR) computed from CT (FFRCT). Improving diagnostic accuracy by combining the anatomic aspects of coronary CTA with a physiologic assessment via CT perfusion or FFRCT may reduce the need for additional testing to evaluate for ischemia, reduce downstream costs and risks associated with an invasive procedure, and lead to improved patient outcomes. Given a rapidly expanding body of research in this field, this comparative review summarizes the present literature while contrasting the benefits, limitations, and future directions in myocardial CT perfusion and FFRCT imaging. PMID:25151919

  7. Multidetector CT of blunt abdominal trauma.

    PubMed

    Soto, Jorge A; Anderson, Stephan W

    2012-12-01

    The morbidity, mortality, and economic costs resulting from trauma in general, and blunt abdominal trauma in particular, are substantial. The "panscan" (computed tomographic [CT] examination of the head, neck, chest, abdomen, and pelvis) has become an essential element in the early evaluation and decision-making algorithm for hemodynamically stable patients who sustained abdominal trauma. CT has virtually replaced diagnostic peritoneal lavage for the detection of important injuries. Over the past decade, substantial hardware and software developments in CT technology, especially the introduction and refinement of multidetector scanners, have expanded the versatility of CT for examination of the polytrauma patient in multiple facets: higher spatial resolution, faster image acquisition and reconstruction, and improved patient safety (optimization of radiation delivery methods). In this article, the authors review the elements of multidetector CT technique that are currently relevant for evaluating blunt abdominal trauma and describe the most important CT signs of trauma in the various organs. Because conservative nonsurgical therapy is preferred for all but the most severe injuries affecting the solid viscera, the authors emphasize the CT findings that are indications for direct therapeutic intervention. PMID:23175542

  8. Noncontrast helical CT for ureteral stones.

    PubMed

    Boridy, I C; Nikolaidis, P; Kawashima, A; Sandler, C M; Goldman, S M

    1998-01-01

    Noncontrast helical computed tomography (CT) has recently been found to be superior to excretory urography (IVU) in the evaluation of patients with suspected ureterolithiasis. Noncontrast helical CT does not require the use of intravenous contrast material with its associated cost and risk of adverse reactions and can be completed within 5 min, in most cases. Noncontrast CT often detects extraurinary pathology responsible for the patient's symptoms. CT is also more sensitive than IVU in detecting the calculus, regardless of its size, location, and chemical composition. However, confidently differentiating ureteral calculi from phleboliths along the course of the ureter may, at times, be difficult. The "tissue-rim" sign, a rim of soft tissue attenuation around the suspicious calcification, is helpful in making this distinction. Noncontrast CT does not provide physiological information about renal function and the degree of obstruction. A pilot study has suggested a proportional relationship between the extent of perinephric edema and the degree of obstruction. The cost of the examination and the radiation dose delivered to the patient may be higher with CT. Despite these limitations, noncontrast helical CT has quickly become the imaging study of choice in evaluating patients with acute flank pain. PMID:9542010

  9. Cytomegalovirus pneumonia in transplant patients: CT findings

    SciTech Connect

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

    1996-03-01

    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 included 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.

  10. Ion Stopping Powers and CT Numbers

    SciTech Connect

    Moyers, Michael F.; Sardesai, Milind; Sun, Sean; Miller, Daniel W.

    2010-10-01

    One of the advantages of ion beam therapy is the steep dose gradient produced near the ion's range. Use of this advantage makes knowledge of the stopping powers for all materials through which the beam passes critical. Most treatment planning systems calculate dose distributions using depth dose data measured in water and an algorithm that converts the kilovoltage X-ray computed tomography (CT) number of a given material to its linear stopping power relative to water. Some materials present in kilovoltage scans of patients and simulation phantoms do not lie on the standard tissue conversion curve. The relative linear stopping powers (RLSPs) of 21 different tissue substitutes and positioning, registration, immobilization, and beamline materials were measured in beams of protons accelerated to energies of 155, 200, and 250 MeV; carbon ions accelerated to 290 MeV/n; and iron ions accelerated to 970 MeV/n. These same materials were scanned with both kilovoltage and megavoltage CT scanners to obtain their CT numbers. Measured RLSPs and CT numbers were compared with calculated and/or literature values. Relationships of RLSPs to physical densities, electronic densities, kilovoltage CT numbers, megavoltage CT numbers, and water equivalence values converted by a treatment planning system are given. Usage of CT numbers and substitution of measured values into treatment plans to provide accurate patient and phantom simulations are discussed.

  11. Advances in CT imaging for urolithiasis

    PubMed Central

    Andrabi, Yasir; Patino, Manuel; Das, Chandan J.; Eisner, Brian; Sahani, Dushyant V.; Kambadakone, Avinash

    2015-01-01

    Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice. PMID:26166961

  12. Advances in CT imaging for urolithiasis.

    PubMed

    Andrabi, Yasir; Patino, Manuel; Das, Chandan J; Eisner, Brian; Sahani, Dushyant V; Kambadakone, Avinash

    2015-01-01

    Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice. PMID:26166961

  13. Normalized CT Dose Index of the CT Scanners Used in the National Lung Screening Trial

    PubMed Central

    Cody, Dianna D.; Kim, Hyun-Jung; Cagnon, Christopher H.; Larke, Frederick J.; McNitt-Gray, Michael M.; Kruger, Randell L.; Flynn, Michael J.; Seibert, J. Anthony; Judy, Philip F.; Wu, Xizeng

    2010-01-01

    The National Lung Screening Trial (NLST) includes 33 participating institutions, which performed 75, 133 lung cancer screening CT exams from 26,724 subjects during 2002–2007. For trial quality assurance reasons, CT radiation dose measurement data were collected from all multidetector-row CT scanners used in the NLST. A total of 247 measurements on 96 multi-row detector scanners were collected using a standard CT dose index (CTDI) measurement protocol. The scan parameters employed in the measurements (tube voltage, mAs and detector-channel configuration) were set according to trial-protocol for average size subjects. The normalized CTDIw (computed as CTDIw /mAs) obtained from each trial-participating scanner was tabulated. This study demonstrated a statistically significant difference in normalized CT dose index among CT scanner manufacturers, likely due to design differences such as filtration, bow-tie design and geometry. Our findings also indicated a statistically significant difference in normalized CT dose index among CT scanner models within GE, Siemens, and Philips. We also demonstrated a statistically significant difference in normalized CT dose index among all models and all manufacturers. And, we demonstrated a statistically significant difference in normalized CT dose index from CT scanners among manufacturers when grouped by 4 or 8 data channels vs 16, 32, or 64 channels, suggesting improved dose efficiency in more complex scanners. Average normalized CT dose index values varied by almost a factor of two across all scanners from all manufacturers. This study was focused on machine specific normalized CT dose index; patient dose and image quality were not addressed. PMID:20489094

  14. Falx Cerebri Ossification: CT and MRI Evaluation.

    PubMed

    Tsitouridis, I; Natsis, K; Goutsaridou, F; Tsitouridis, K; Tarazi, L; Chondromatidou, S; Papapostolou, P; Papastergiou, C; Emmanouilidou, M

    2006-11-30

    During the last three years, CT and MRI brain scans of 40 patients revealed falx cerebri partial ossification as an incidental finding. The patients had been admitted for brain CT and MRI for several reasons. In most cases, there was no problem in the differential diagnosis of falx cerebri ossification during interpretation of the cases. In a few cases, the lesion should be distinguished from calcified meningioma, small hematoma in the interhemispheric fissure and in one case there was also meningeal infiltration of breast cancer. In these cases both CT and MRI scans of the brain were evaluated and a definite diagnosis was made. PMID:24351265

  15. CT & CBCT imaging: assessment of the orbits.

    PubMed

    Hatcher, David C

    2012-11-01

    The orbits can be visualized easily on routine or customized protocols for computed tomography (CT) or cone beam CT (CBCT) scans. Detailed orbital investigations are best performed with 3-dimensional imaging methods. CT scans are preferred for visualizing the osseous orbital anatomy and fissures while magnetic resonance imaging is preferred for evaluating tumors and inflammation. CBCT provides high-resolution anatomic data of the sinonasal spaces, airway, soft tissue surfaces, and bones but does not provide much detail within the soft tissues. This article discusses CBCT imaging of the orbits, osseous anatomy of the orbits, and CBCT investigation of selected orbital pathosis. PMID:22981080

  16. Pediatric CT: Strategies to Lower Radiation Dose

    PubMed Central

    Zacharias, Claudia; Alessio, Adam M.; Otto, Randolph K.; Iyer, Ramesh S.; Philips, Grace S.; Swanson, Jonathan O.; Thapa, Mahesh M.

    2016-01-01

    OBJECTIVE The introduction of MDCT has increased the utilization of CT in pediatric radiology along with concerns for radiation sequelae. This article reviews general principles of lowering radiation dose, the basic physics that impact radiation dose, and specific CT integrated dose-reduction tools focused on the pediatric population. CONCLUSION The goal of this article is to provide a comprehensive review of the recent literature regarding CT dose reduction methods, their limitations, and an outlook on future developments with a focus on the pediatric population. The discussion will initially focus on general considerations that lead to radiation dose reduction, followed by specific technical features that influence the radiation dose. PMID:23617474

  17. Acute orbital pseudotumors: classification and CT features

    SciTech Connect

    Nugent, R.A.; Rootman, J.; Robertson, W.D.; Lapointe, J.S.; Harrison, P.B.

    1981-11-01

    Acute orbital pseudotumors are inflammatory lesions of unknown etiology that may affect part or, less often, all of the tissue within the orbit. A retrospective computed tomographic (CT) study of 16 patients demonstrated that these lesions occur in one of five specific anatomic patterns: anterior, posterior, diffuse, lacrimal, or myositic. The most common location was lacrimal followed by anterior psuedotumors. Posterior, diffuse, and myositic pseudotumors were equally frequent. Localization on the basis of clinical features correlated with the CT localization. Illustrative cases of each of the five types are included. The role of CT in evaluating the therapeutic response is discussed.

  18. The challenges of CT colonography reimbursement.

    PubMed

    Dachman, Abraham H; Yee, Judy

    2013-12-01

    CT colonography has been shown to be an effective method to screen for colorectal cancer. However, at present, full endorsement and reimbursement for screening CT colonography, particularly by the US Preventive Services Task Force and CMS, respectively, are absent, so this screening option is infrequently used, and optical colonoscopy remains the de facto standard screening option. The authors summarize the past accomplishments that led to the current state of reimbursement and outline the remaining challenges and road to full acceptance and reimbursement of screening CT colonography nationally. PMID:24295944

  19. CT in pyogenic osteomyelitis of the spine

    SciTech Connect

    Kattapuram, S.V.; Phillips, W.C.; Boyd, R.

    1983-06-01

    Six patients with bacteriologically proven pyogenic osteomyelitis of the spine were followed serially with computed tomography (CT). Initial evaluation of the involved vertebral bodies and adjacent soft tissues showed a drop in CT numbers when compared to normal cancellous bone and soft tissues. A soft-tissue mass was seen in all cases. After appropriate antibiotic therapy, all six patients showed an increase in bone density and a diminution of the soft-tissue mass (p < 0.05). Five of the six patients showed a further decrease in soft-tissue CT numbers.

  20. CT of osteomyelitis of the spine

    SciTech Connect

    Golimbu, C.; Firooznia, H.; Rafii, M.

    1984-01-01

    Computed tomography (CT) scans were performed in 17 adults with osteomyelitis of the spine. The dominant features were paravertebral soft-tissue swelling, abscess formation, and bone erosion. In two patients there were no findings indicative of osteomyelitis on conventional radiographs, but CT revealed paravertebral abscesses and bone lysis, helping to establish the diagnosis of osteomyelitis, chiefly because of its ability to detect early erosion of spongy vertabral bone, disk involvement, paravertebral soft-tissue swelling or abscess, and extension of the pathology into the spinal canal. Furthermore, CT facilitated closed-needle biopsy, helping to establish the pathologic diagnosis.

  1. Cine CT technique for dynamic airway studies

    SciTech Connect

    Ell, S.R.; Jolles, H.; Keyes, W.D.; Galvin, J.R.

    1985-07-01

    The advent of cine CT scanning with its 50-msec data acquisition time promises a much wider range of dynamic CT studies. The authors describe a method for dynamic evaluation of the extrathoracic airway, which they believe has considerable potential application in nonfixed upper-airway disease, such as sleep apnea and stridor of unknown cause. Conventional CT is limited in such studies by long data acquisition time and can be used to study only prolonged maneuvers such as phonation. Fluoroscopy and digital subtraction studies are limited by relatively high radiation dose and inability to image all wall motions simultaneously.

  2. Photon counting spectral CT versus conventional CT: comparative evaluation for breast imaging application

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.; Fritz, Shannon G.

    2011-04-01

    Spectral CT systems with photon counting detectors have more advantages compared to conventional CT systems. However, clinical applications have been hampered for a long time due to the high demands of clinical systems and limitations of spectroscopic x-ray detectors. Photon counting detector technology has gained considerable improvements in the past decade, and spectral CT has become a hot topic. Several experimental spectral CT systems are under investigation. The purpose of this work was to perform the first direct, side-by-side comparison of existing spectral CT technology with a mature clinical CT system based on a conventional energy integrating detector. We have built an experimental spectral CT system whose main parameters are similar to the parameters of a clinical CT system. The system uses a spectroscopic cadmium zinc telluride (CZT) detector. The detector includes two rows of CZT pixels with 256 pixels in each row. The pixel size is 1 × 1 mm2, and the maximum count rate is 2 Mcounts/pixel/s. The spectral CT system has a magnification factor of 1.62 and the source to detector and source to image distances of 85 and 53 cm, respectively. The above parameters are similar to those of the clinical CT system, Siemens Sensation 16, used for comparison. The two systems were compared by imaging spatial resolution and contrast resolution phantoms made from acrylic cylinders with 14 cm diameters. The resolution phantom included Al wires with 0.3, 0.6, and 1 mm diameters, and 0.25 g cc-1 CaCO3 contrast. The contrast phantom included contrast elements with 1.7, 5, and 15 mg cc-1 iodine, and 1.1, 3.3, and 10 mg cc-1 gadolinium. The phantoms were imaged with the two systems using 120 kVp tube voltage and 470 mR total skin exposure. The spectral CT showed CT numbers, image noise, and spatial and contrast resolutions to be similar within 10% compared to the Siemens 16 system, and provided an average of 10% higher CNR. However, the spectral CT system had a major

  3. Use of CT in stapedial otosclerosis

    SciTech Connect

    Mafee, M.F.; Henrikson, G.C.; Deitch, R.L.; Norouzi, P.; Kumar, A.; Kriz, R.; Valvassori, G.E.

    1985-09-01

    Otosclerosis (otospongiosis) is a primary focal disease of the labyrinthine capsule. The stapes footplate is fixed when the spongiotic focus expands and invades the oval window. Persons with stapedial otosclerosis experience a progressive conductive hearing loss. In many cases, cochlear degeneration is observed, in which a mixed hearing loss occurs. Using computed tomography (CT), the authors studied the ears of 45 selected patients with conductive or mixed hearing loss. CT proved valuable in determining otosclerotic changes of the oval window and otic capsule. Spongiotic changes of the otic capsule are better appreciated by CT than complex motion tomography. The usefulness of CT in diagnosing other causes of conductive or mixed hearing loss is also described.

  4. CT of thrombosed arteriovenous malformations in children

    SciTech Connect

    Mitnick, J.S.; Pinto, R.S.; Lin, J.P.; Rose, H.; Lieberman, A.

    1984-02-01

    Thrombosed arteriovenous malformations (AVMs) in children are rare lesions that may present with headaches or a seizure disorder. Thirteen patients (4 months to 21 years of age) with this lesion were examined with computed tomography (CT). In 11 patients surgical confirmation was obtained, and the other two patients were examined with follow-up CT scans. Angiography either showed an avascular mass (7/13) or was negative (6/13). CT showed a lobulated lesion (8/13), peripheral location (11/13), and minimal surrounding edema (8/13). All of the lesions were hyperdense prior to the administration of contrast material and all enhanced either slightly or not at all following contrast material administration. It is concluded that these characteristic CT features aid in making the diagnosis of thrombosed AVM. The major differential diagnosis is small intracerebral neoplasm.

  5. CT in the diagnosis of enterovesical fistulae

    SciTech Connect

    Goldman, S.M.; Fishman, E.K.; Gatewood, O.M.B.; Jones, B.; Siegelman, S.S.

    1985-06-01

    Enterovesical fistulae are difficult to demonstrate by conventional radiographic methods. Computed tomography (CT), a sensitive, noninvasive method of documenting the presence of such fistulae, is unique in its ability to outline the extravesical component of the primary disease process. Twenty enterovesical fistulae identified by CT were caused by diverticulitis (nine), carcinoma of the rectosigmoid (two), Crohn disease (three), gynecologic tumors (two), bladder cancer (one), cecal carcinoma (one), prostatic neoplasia (one), and appendiceal abscess (one). The CT findings included intravesical air (90%), passage of orally or rectally administered contrast medium into the bladder (20%), focal bladder-wall thickening (90%), thickening of adjacent bowel wall (85%), and an extraluminal mass that often contained air (75%). CT proved to be an important new method in the diagnosis of enterovesical fistulae.

  6. Principle and applications of dual source CT

    NASA Astrophysics Data System (ADS)

    Flohr, Thomas

    2008-08-01

    Dual source CT (DSCT) has the potential to solve remaining limitations of conventional multi-detector row CT (MDCT)-scanners, such as insufficient temporal resolution for ECG-controlled cardiac imaging. A DSCT is equipped with two X-ray tubes and two corresponding detectors that are mounted onto the rotating gantry with an angular offset of 90°. The key benefit of DSCT for cardiac scanning is improved temporal resolution equivalent to a quarter of the gantry rotation time (83 ms at 0.33 s rotation time). Additionally, both X-ray tubes can be operated at different kV- and mA-settings, enabling the acquisition of dual energy data. The acquisition of dual energy CT data can add functional information to the morphological information based on different X-ray attenuation coefficients that is usually obtained in a CT examination.

  7. Acute pancreatitis: prognostic value of CT

    SciTech Connect

    Balthazar, E.J.; Ranson, J.H.C.; Naidich, D.P.; Megibow, A.J.; Caccavale, R.; Cooper, M.M.

    1985-09-01

    In 83 patients with acute pancreatitis, the initial computed tomographic (CT) examinations were classified by degree of disease severity (grades A-E) and were correlated with the clinical follow-up, objective prognostic signs, and complications and death. The length of hospitalization correlated well with the severity of the initial CT findings. Abscesses occurred in 21.6% of the entire group, compared with 60.0% of grade E patients. Pleural effusions were also more common in grade E patients. Abscesses were seen in 80.0% of patients with six to eight prognostic signs, compared with 12.5% of those with zero to two. The use of prognostic signs with initial CT findings results in improved prognostic accuracy. Early CT examination of patients with acute pancreatitis is a useful prognostic indicator of morbidity and mortality.

  8. CT of soft-tissue neoplasms

    SciTech Connect

    Weekes, R.G.; McLeod, R.A.; Reiman, H.M.; Pritchard, D.J.

    1985-02-01

    The computed tomographic scans (CT) of 84 patients with untreated soft-tissue neoplasms were studied, 75 with primary and nine with secondary lesions. Each scan was evaluated using several criteria: homogeneity and density, presence and type of calcification, presence of bony destruction, involvement of multiple muscle groups, definition of adjacent fat, border definition, and vessel or nerve involvement. CT demonstrated the lesion in all 84 patients and showed excellent anatomic detail in 64 of the 75 patients with primary neoplasms. The CT findings were characteristic enough to suggest the histology of the neoplasm in only 13 lesions (nine lipomas, three hemangiomas, one neurofibroma). No malignant neoplasm had CT characteristics specific enough to differentiate it from any other malignant tumor. However, malignant neoplasms could be differentiated from benign neoplasms in 88% of the cases.

  9. SPECT/CT in pediatric patient management.

    PubMed

    Nadel, Helen R

    2014-05-01

    Hybrid SPECT/CT imaging is becoming the standard of care in pediatric imaging. Indications are mainly for oncologic imaging including mIBG scintigraphy for neuroblastoma and I-123 post surgical imaging of children with thyroid carcinoma, bone scintigraphy for back pain, children referred from sports medicine and neurodevelopmentally delayed children presenting with pain symptoms. The studies provide improved diagnostic accuracy, and oncologic imaging that includes optimized CT as part of the SPECT/CT study may decrease the number of studies and sedation procedures an individual child may need. The studies, however, must be tailored on an individual basis as the addition of the CT study can increase exposure to the child and should only be performed after appropriate justification and with adherence to optimized low dose pediatric protocols. PMID:24554052

  10. CT Image Presentations For Oral Surgery

    NASA Astrophysics Data System (ADS)

    Rhodes, Michael L.; Rothman, Stephen L. G.; Schwarz, Melvyn S.; Tivattanasuk, Eva S.

    1988-06-01

    Reformatted CT images of the mandible and maxilla are described as a planning aid to the surgical implantation of dental fixtures. Precisely scaled and cross referenced axial, oblique, CT generated panorex, and 3-D images are generated to help indicate where and how critical anatomic structures are positioned. This information guides the oral surgeon to those sites where dental implants have optimal osteotic support and least risk to sensitive neural tissue. Oblique images are generated at 1-2 mm increments along the arch of the mandible (or maxilla). Each oblique is oriented perpendicular to the local arch curvature. The adjoining five CT generated panorex views match the patient's mandibular (or maxilla) arch, with each of the views separated by twice the distance between axial CT slices. All views are mutually cross-referenced to show fine detail of the underlying mandibular (or maxilla) structure. Several exams are illustrated and benefit to subsequent surgery is assessed.

  11. CT and PET-CT of a Dog with Multiple Pulmonary Adenocarcinoma

    PubMed Central

    KIM, Jisun; KWON, Seong Young; CENA, Rohani; PARK, Seungjo; OH, Juyeon; OUI, Heejin; CHO, Kyoung-Oh; MIN, Jung-Joon; CHOI, Jihye

    2013-01-01

    ABSTRACT A 10-year-old, intact female Yorkshire terrier had multiple pulmonary nodules on thoracic radiography and ultrasonography with no lesions elsewhere. Computed tomography (CT) and positron emission tomography and computed tomography (PET-CT) using 18F-fluorodeoxyglucose (FDG) were performed to identify metastasis and undetected primary tumors. On CT examination, pulmonary nodules had a hypoattenuating center with thin peripheral enhancement, suggesting ischemic or necrotizing lesion. In PET-CT at 47 min after intravenous injection of 11.1 MBq/kg of FDG, the maximum standardized uptake value of each pulmonary nodule was about from 3.8 to 6.4. There were no abnormal lesions except for four pulmonary nodules on the CT and PET-CT. Primary lung tumor was tentatively diagnosed, and palliative therapy using 2 mg/kg tramadol and 2.2 mg/kg carprofen twice per day was applied. After the dog’s euthanasia due to deteriorated clinical signs and poor prognosis, undifferentiated pulmonary adenocarcinoma was diagnosed through histopathologic and immunochemistry examination. To the best of the authors’ knowledge, this is the first study of CT and PET-CT features of canine pulmonary adenocarcinoma. In this case, multiple pulmonary adenocarcinoma could be determined on the basis of FDG PET-CT through screening the obvious distant metastasis and/or lymph node invasions and excluding unknown primary tumors. PMID:24389742

  12. Progress in Fully Automated Abdominal CT Interpretation

    PubMed Central

    Summers, Ronald M.

    2016-01-01

    OBJECTIVE Automated analysis of abdominal CT has advanced markedly over just the last few years. Fully automated assessment of organs, lymph nodes, adipose tissue, muscle, bowel, spine, and tumors are some examples where tremendous progress has been made. Computer-aided detection of lesions has also improved dramatically. CONCLUSION This article reviews the progress and provides insights into what is in store in the near future for automated analysis for abdominal CT, ultimately leading to fully automated interpretation. PMID:27101207

  13. CT of trauma to the abnormal kidney

    SciTech Connect

    Rhyner, P.; Federle, M.P.; Jeffrey, R.B.

    1984-04-01

    Traumatic injuries to already abnormal kidneys are difficult to assess by excretory urography and clinical evaluation. Bleeding and urinary extravasation may accompany minor trauma; conversely, underlying tumors, perirenal hemorrhage, and extravasation may be missed on urography. Computed tomography (CT) was performed in eight cases including three neoplasms, one adult polycystic disease, one simple renal cyst, two hydronephrotic kidneys, and one horseshoe kidney. CT provided specific and clinically useful information in each case that was not apparent on excretory urography.

  14. CT Scans - Multiple Languages: MedlinePlus

    MedlinePlus

    ... 繁體中文) French (français) Hindi (हिन्दी) Japanese (日本語) Korean (한국어) Russian (Русский) Somali (af Soomaali) Spanish (español) ... スキャン - 日本語 (Japanese) Bilingual PDF Health Information Translations Korean (한국어) CT (Computerized Tomography) Scan CT 스캔 (전산화 ...

  15. Performance evaluation of the General Electric eXplore CT 120 micro-CT using the vmCT phantom

    NASA Astrophysics Data System (ADS)

    Bahri, M. A.; Warnock, G.; Plenevaux, A.; Choquet, P.; Constantinesco, A.; Salmon, E.; Luxen, A.; Seret, A.

    2011-08-01

    The eXplore CT 120 is the latest generation micro-CT from General Electric. It is equipped with a high-power tube and a flat-panel detector. It allows high resolution and high contrast fast CT scanning of small animals. The aim of this study was to compare the performance of the eXplore CT 120 with that of the eXplore Ultra, its predecessor for which the methodology using the vmCT phantom has already been described [1].The phantom was imaged using typical a rat (fast scan or F) or mouse (in vivo bone scan or H) scanning protocols. With the slanted edge method, a 10% modulation transfer function (MTF) was observed at 4.4 (F) and 3.9-4.4 (H) mm-1 corresponding to 114 μm resolution. A fairly larger MTF was obtained by the coil method with the MTF for the thinnest coil (3.3 mm-1) equal to 0.32 (F) and 0.34 (H). The geometric accuracy was better than 0.3%. There was a highly linear (R2>0.999) relationship between measured and expected CT numbers for both the CT number accuracy and linearity sections of the phantom. A cupping effect was clearly seen on the uniform slices and the uniformity-to-noise ratio ranged from 0.52 (F) to 0.89 (H). The air CT number depended on the amount of polycarbonate surrounding the area where it was measured; a difference as high as approximately 200 HU was observed. This hindered the calibration of this scanner in HU. This is likely due to the absence of corrections for beam hardening and scatter in the reconstruction software. However in view of the high linearity of the system, the implementation of these corrections would allow a good quality calibration of the scanner in HU. In conclusion, the eXplore CT 120 achieved a better spatial resolution than the eXplore Ultra (based on previously reported specifications) and future software developments will include beam hardening and scatter corrections that will make the new generation CT scanner even more promising.

  16. CT features of pleural masses and nodules.

    PubMed

    Reetz, Jennifer A; Buza, Elizabeth L; Krick, Erika L

    2012-01-01

    Pleural space masses and nodules are rarely described on computed tomography (CT) in veterinary medicine and have only been described in patients with neoplasia. Our purpose was to describe the CT findings and diagnoses in seven patients with pleural masses and nodules. Two patients had broad-based, plaque-like pleural masses, both of which were due to neoplasia (primary pleural carcinoma, metastatic thymoma). Two patients had well-defined pleural nodules and nodular pleural thickening, one of which had mesothelial hypertrophy, and another of which had metastatic hemangiosarcoma. Three patients had ill-defined pleural nodules to nodular pleural thickening, one of which had metastatic pulmonary carcinoma, while the other two had bacterial infection with mesothelial proliferation (n = 2), fibrinous pleuritis (n = 1), and severe mediastinal pleuritis/mediastinitis (n = 2). Five of the seven patients had focal, multifocal or diffuse smooth, and/or irregular pleural thickening. Five of seven patients had pleural effusion, and postcontrast CT was useful in several patients for delineating the pleural lesions from the effusion. All patients except one had additional lesions identified on CT besides those in the pleural space. CT is useful in identifying and characterizing pleural space lesions and could be used to guide further diagnostic procedures such as thoracoscopy or exploratory thoracotomy. Both neoplastic and nonneoplastic diseases should be considered in the differential diagnoses for pleural space masses and nodules found on CT. PMID:22092656

  17. CT imaging of enhanced oil recovery experiments

    SciTech Connect

    Gall, B.L.

    1992-12-01

    X-ray computerized tomography (Cr) has been used to study fluid distributions during chemical enhanced oil recovery experiments. Four CT-monitored corefloods were conducted, and oil saturation distributions were calculated at various stages of the experiments. Results suggested that this technique could add significant information toward interpretation and evaluation of surfactant/polymer EOR recovery methods. CT-monitored tracer tests provided information about flow properties in the core samples. Nonuniform fluid advance could be observed, even in core that appeared uniform by visual inspection. Porosity distribution maps based on CT density calculations also showed the presence of different porosity layers that affected fluid movement through the cores. Several types of CT-monitored corefloods were conducted. Comparisons were made for CT-monitored corefloods using chemical systems that were highly successful in reducing residual oil saturations in laboratory experiments and less successful systems. Changes were made in surfactant formulation and in concentration of the mobility control polymer. Use of a poor mobility control agent failed to move oil that was not initially displaced by the injected surfactant solution; even when a good'' surfactant system was used. Use of a less favorable surfactant system with adequate mobility control could produce as much oil as the use of a good surfactant system with inadequate mobility control. The role of mobility control, therefore, becomes a critical parameter for successful application of chemical EOR. Continuation of efforts to use CT imaging in connection with chemical EOR evaluations is recommended.

  18. CT imaging of enhanced oil recovery experiments

    SciTech Connect

    Gall, B.L.

    1992-12-01

    X-ray computerized tomography (Cr) has been used to study fluid distributions during chemical enhanced oil recovery experiments. Four CT-monitored corefloods were conducted, and oil saturation distributions were calculated at various stages of the experiments. Results suggested that this technique could add significant information toward interpretation and evaluation of surfactant/polymer EOR recovery methods. CT-monitored tracer tests provided information about flow properties in the core samples. Nonuniform fluid advance could be observed, even in core that appeared uniform by visual inspection. Porosity distribution maps based on CT density calculations also showed the presence of different porosity layers that affected fluid movement through the cores. Several types of CT-monitored corefloods were conducted. Comparisons were made for CT-monitored corefloods using chemical systems that were highly successful in reducing residual oil saturations in laboratory experiments and less successful systems. Changes were made in surfactant formulation and in concentration of the mobility control polymer. Use of a poor mobility control agent failed to move oil that was not initially displaced by the injected surfactant solution; even when a ``good`` surfactant system was used. Use of a less favorable surfactant system with adequate mobility control could produce as much oil as the use of a good surfactant system with inadequate mobility control. The role of mobility control, therefore, becomes a critical parameter for successful application of chemical EOR. Continuation of efforts to use CT imaging in connection with chemical EOR evaluations is recommended.

  19. CT Pneumocolonography In Normal Dogs

    PubMed Central

    Steffey, Michele A.; Daniel, Leticia; Taylor, Sandra L.; Chen, Rachel X.; Zwingenberger, Allison L.

    2014-01-01

    Objectives of this experimental study were to describe effects of varying technical components that may contribute to an optimal protocol for CT pneumocolonography (CTP) in dogs, and to develop a standardized methodology for CTP as a future potential diagnostic tool in canine clinical patients with large bowel disease. Eight purpose-bred intact male hound cross research dogs were enrolled and randomized to groups based on variables of pressure/body position (n=4) and insufflation time (n=4). For each segment of large bowel (rectum, colorectal junction, descending colon, transverse colon, ascending colon), the adequacy of bowel preparation, % of bowel lumen filled with fecal material, and bowel tortuosity or folding were assessed. Measurements of bowel wall thickness (cm), cross-sectional bowel lumen diameter (cm), and cross-sectional bowel luminal area (cm2) were obtained at standardized locations within the large bowel. False discovery rates (FDR) were calculated to adjust for multiple testing. Values of FDR < 0.05 were considered significant. Differences in mean cross-sectional area and diameter and bowel wall thickness under increasing pressure were not significant after adjusting for multiple testing; some had raw p values <0.05. Ascending colon diameter and ascending colon area significantly increased with insufflation time (FDR<0.05). No other response variables showed a significant change with insufflation time. The optimal insufflation pressure for maintaining pneumocolon in this study was determined to be 20 mmHg. CTP is a feasible technique to provide consistent distension for imaging of the large bowel and further study on application of CTP in clinical patients is warranted. PMID:25545308

  20. Computing effective dose in cardiac CT

    NASA Astrophysics Data System (ADS)

    Huda, Walter; Tipnis, Sameer; Sterzik, Alexander; Schoepf, U. Joseph

    2010-07-01

    We present a method of estimating effective doses in cardiac CT that accounts for selected techniques (kV mAs-1), anatomical location of the scan and patient size. A CT dosimetry spreadsheet (ImPACT CT Patient Dosimetry Calculator) was used to estimate effective doses (E) using ICRP 103 weighting factors for a 70 kg patient undergoing cardiac CT examinations. Using dose length product (DLP) for the same scans, we obtained values of E/DLP for three CT scanners used in cardiac imaging from two vendors. E/DLP ratios were obtained as a function of the anatomical location in the chest and for x-ray tube voltages ranging from 80 to 140 kV. We also computed the ratio of the average absorbed dose in a water cylinder modeling a patient weighing W kg to the corresponding average absorbed dose in a water cylinder equivalent to a 70 kg patient. The average E/DLP for a 16 cm cardiac heart CT scan was 26 µSv (mGy cm)-1, which is about 70% higher than the current E/DLP values used for chest CT scans (i.e. 14-17 µSv (mGy cm)-1). Our cardiac E/DLP ratios are higher because the cardiac region is ~30% more radiosensitive than the chest, and use of the ICRP 103 tissue weighting factors increases cardiac CT effective doses by ~30%. Increasing the x-ray tube voltage from 80 to 140 kV increases the E/DLP conversion factor for cardiac CT by 17%. For the same incident radiation at 120 kV, doses in 45 kg adults were ~22% higher than those in 70 kg adults, whereas doses in 120 kg adults were ~28% lower. Accurate estimates of the patient effective dose in cardiac CT should use ICRP 103 tissue weighting factors, and account for a choice of scan techniques (kV mAs-1), exposed scan region, as well as patient size.

  1. Current role of hybrid CT/angiography system compared with C-arm cone beam CT for interventional oncology

    PubMed Central

    Arai, Y; Inaba, Y; Inoue, M; Nishiofuku, H; Anai, H; Hori, S; Sakaguchi, H; Kichikawa, K

    2014-01-01

    Hybrid CT/angiography (angiography) system and C-arm cone beam CT provide cross-sectional imaging as an adjunct to angiography. Current interventional oncological procedures can be conducted precisely using these two technologies. In this article, several cases using a hybrid CT/angiography system are shown first, and then the advantages and disadvantages of the hybrid CT/angiography and C-arm cone beam CT are discussed with literature reviews. PMID:24968749

  2. CT vs. MRCP in choledocholithiasis jaundice

    PubMed Central

    Petrescu, I; Bratu, AM; Petrescu, S; Popa, BV; Cristian, D; Burcos, T

    2015-01-01

    Rationale: Obstructive jaundice can raise problems to diagnostic imaging. The radiologist must choose the most appropriate examination that delivers the most important diagnostic information because the differences between a lithiasic obstruction and a tumoral one are vital. This information helps the surgeon speed up the process of decision-making, because the treatment may be very different in relation to the nature of the obstruction. Objective: This study tries to demonstrate the diagnostic accuracy of computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP) in detecting the obstacle in the common bile duct (CBD) and the possibility of establishing the lithiasic nature of the obstruction. Methods and Results: A retrospective analysis was analyzed during an interval of 18 months that included jaundice patients admitted in the General Surgery Department of “Coltea” Clinical Hospital. They were examined by CT scanning and by MRCP, being suspected of choledocholithiasis. 63 patients were included in the study, 34 females and 29 males. 33 CT scans and 30 MRCP exams were performed. Discussion: CT scan is useful in detecting residual or iterative choledocholithiasis in patients after cholecystectomy, contrast enhanced CT (CECT), being able to differentiate between lithiasic and non-lithiasic obstruction. MRCP delivers important anatomic details of the biliary tree; it is superior to CT in diagnosing the hepatocholedochal lithiasis; MRCP tends to replace endoscopic retrograde cholangiopancreatography (ERCP) - the diagnostic “gold standard” reducing the number of unnecessary invasive diagnostic procedures. Abbreviations: CT = computed tomography, CECT = contrast enhanced computed tomography, ERCP = endoscopic retrograde cholangiopancreatography, MRCP = magnetic resonance cholangiopancreatography, CBD = common bile duct PMID:25866583

  3. Metrology with μCT: precision challenge

    NASA Astrophysics Data System (ADS)

    Suppes, Alexander; Neuser, Eberhard

    2008-08-01

    Over the last years computed tomography (CT) with conventional x-ray sources has evolved from imaging method in medicine to a well established technology for industrial applications in the field of material science, microelectronics, geology, etc. By using modern microfocus and nanofocus® X-ray tubes, parts can be scanned with sub-micrometer resolutions. Currently, micro-CT is used more and more as a technology for metrological applications. Especially if complex parts with hidden or difficult accessible surfaces have to be measured, CT offers big advantages comparing with conventional tactile or optical coordinate measuring machines (CMMs): high density of measurement points and fast capturing of the complete sample's geometry. When using this modern technology the question arises how precise a CT based CMM can measure in comparison to conventional CMMs? To characterize the metrological capabilities of a tactile or optical CMM, internationally standardized characteristics like length measurement error and probing error are used. To increase the acceptance of CT as a metrological method, the definition and usage of these parameters is important. In this paper, an overview of the process chain in CT based metrology will be given and metrological characteristics will be described. With the help of a special material standard designed and calibrated by PTB-National Metrology Institute of Germany-the influence of methods for beam hardening correction and for surface extraction on the metrological characteristics will be analyzed. It will be shown that with modern micro-CT systems length measurement error of less than 1μm for an object diameter of 20 mm can be reached.

  4. CRYPTOSPORIDIUM LOG-INACTIVATION WITH OZONE USING EFFLUENT CT 10, GEOMETRIC MEAN CT 10 EXTENDED INTEGRATED CT 10 AND EXTENDED-CSTR CALCULATIONS

    EPA Science Inventory

    The draft Long Term 2 Enhanced Surface Water Treatment Rule ("LT2ESWTR") contains Cryptosporidium log-inactivation CT tables. Depending on the water temperature, the Cryptosporidium CT values that are listed are 15 to 25 times greater than CT values fo...

  5. Friction Reduction for Microhole CT Drilling

    SciTech Connect

    Ken Newman; Patrick Kelleher; Edward Smalley

    2007-03-31

    The objective of this 24 month project focused on improving microhole coiled tubing drilling bottom hole assembly (BHA) reliability and performance, while reducing the drilling cost and complexity associated with inclined/horizontal well sections. This was to be accomplished by eliminating the need for a downhole drilling tractor or other downhole coiled tubing (CT) friction mitigation techniques when drilling long (>2,000 ft.) of inclined/horizontal wellbore. The technical solution to be developed and evaluated in this project was based on vibrating the coiled tubing at surface to reduce the friction along the length of the downhole CT drillstring. The Phase 1 objective of this project centered on determining the optimum surface-applied vibration system design for downhole CT friction mitigation. Design of the system would be based on numerical modeling and laboratory testing of the CT friction mitigation achieved with various types of surface-applied vibration. A numerical model was developed to predict how far downhole the surface-applied vibration would travel. A vibration test fixture, simulating microhole CT drilling in a horizontal wellbore, was constructed and used to refine and validate the numerical model. Numerous tests, with varying surface-applied vibration parameters were evaluated in the vibration test fixture. The data indicated that as long as the axial force on the CT was less than the helical buckling load, axial vibration of the CT was effective at mitigating friction. However, surface-applied vibration only provided a small amount of friction mitigation as the helical buckling load on the CT was reached or exceeded. Since it would be impractical to assume that routine field operations be conducted at less than the helical buckling load of the CT, it was determined that this technical approach did not warrant the additional cost and maintenance issues that would be associated with the surface vibration equipment. As such, the project was

  6. Virtual hybrid bronchoscopy using PET/CT data sets

    NASA Astrophysics Data System (ADS)

    Englmeier, Karl-Hans; Seemann, Marcus D.

    2007-03-01

    The aim of this study was to demonstrate the possibilities, advantages and limitations of virtual bronchoscopy using data sets from positron emission tomography (PET) and computed tomography (CT). Eight consecutive patients with lung cancer underwent PET/CT. PET was performed with F-18-labelled 2-[fluorine-18]-fluoro-2-deoxy-D: -glucose ((18)F-FDG). The tracheobronchial system was segmented with a volume-growing algorithm, using the CT data sets, and visualized with a shaded-surface rendering method. The primary tumours and the lymph node metastases were segmented for virtual CT-bronchoscopy using the CT data set and for virtual PET/CT-bronchoscopy using the PET/CT data set. Virtual CT-bronchoscopy using the low-dose or diagnostic CT facilitates the detection of anatomical/morphological structure changes of the tracheobronchial system. Virtual PET/CT-bronchoscopy was superior to virtual CT-bronchoscopy in the detection of lymph node metastases (P=0.001), because it uses the CT information and the molecular/metabolic information from PET. Virtual PET/CT-bronchoscopy with a transparent colour-coded shaded-surface rendering model is expected to improve the diagnostic accuracy of identification and characterization of malignancies, assessment of tumour staging, differentiation of viable tumour tissue from atelectases and scars, verification of infections, evaluation of therapeutic response and detection of an early stage of recurrence that is not detectable or is misjudged in comparison with virtual CT-bronchoscopy.

  7. Chest pain: coronary CT in the ER.

    PubMed

    Maffei, Erica; Seitun, Sara; Guaricci, Andrea I; Cademartiri, Filippo

    2016-01-01

    Cardiac CT has developed into a robust clinical tool during the past 15 years. Of the fields in which the potential of cardiac CT has raised more interest is chest pain in acute settings. In fact, the possibility to exclude with high reliability obstructive coronary artery disease (CAD) in patients at low-to-intermediate risk is of great interest both from the clinical standpoint and from the management standpoint. Several other modalities, with or without imaging, have been used during the past decades in the settings of new onset chest pain or in acute chest pain for both diagnostic and prognostic assessment of CAD. Each one has advantages and disadvantages. Most imaging modalities also focus on inducible ischaemia to guide referral to invasive coronary angiography. The advent of cardiac CT has introduced a new practice diagnostic paradigm, being the most accurate non-invasive method for identification and exclusion of CAD. Furthermore, the detection of subclinical CAD and plaque imaging offer the opportunity to improve risk stratification. Moreover, recent advances of the latest generation CT scanners allow combining both anatomical and functional imaging by stress myocardial perfusion. The role of cardiac CT in acute settings is already important and will become progressively more important in the coming years. PMID:26866681

  8. Medipix-based Spectral Micro-CT

    PubMed Central

    Xu, Qiong; He, Peng; Bennett, James; Amir, Raja; Dobbs, Bruce; Mou, Xuanqin; Wei, Biao; Butler, Anthony; Butler, Phillip; Wang, Ge

    2013-01-01

    Since Hounsfield's Nobel Prize winning breakthrough decades ago, X-ray CT has been widely applied in the clinical and preclinical applications - producing a huge number of tomographic gray-scale images. However, these images are often insufficient to distinguish crucial differences needed for diagnosis. They have poor soft tissue contrast due to inherent photon-count issues, involving high radiation dose. By physics, the X-ray spectrum is polychromatic, and it is now feasible to obtain multi-energy, spectral, or true-color, CT images. Such spectral images promise powerful new diagnostic information. The emerging Medipix technology promises energy-sensitive, high-resolution, accurate and rapid X-ray detection. In this paper, we will review the recent progress of Medipix-based spectral micro-CT with the emphasis on the results obtained by our team. It includes the state- of-the-art Medipix detector, the system and method of a commercial MARS (Medipix All Resolution System) spectral micro-CT, and the design and color diffusion of a hybrid spectral micro-CT. PMID:24194631

  9. Patient doses from CT examinations in Turkey

    PubMed Central

    Ataç, Gökçe Kaan; Parmaksız, Aydın; İnal, Tolga; Bulur, Emine; Bulgurlu, Figen; Öncü, Tolga; Gündoğdu, Sadi

    2015-01-01

    PURPOSE We aimed to establish the first diagnostic reference levels (DRLs) for computed tomography (CT) examinations in adult and pediatric patients in Turkey and compare these with international DRLs. METHODS CT performance information and examination parameters (for head, chest, high-resolution CT of the chest [HRCT-chest], abdominal, and pelvic protocols) from 1607 hospitals were collected via a survey. Dose length products and effective doses for standard patient sizes were calculated from the reported volume CT dose index (CTDIvol). RESULTS The median number of protocols reported from the 167 responding hospitals (10% response rate) was 102 across five different age groups. Third quartile CTDIvol values for adult pelvic and all pediatric body protocols were higher than the European Commission standards but were comparable to studies conducted in other countries. CONCLUSION The radiation dose indicators for adult patients were similar to those reported in the literature, except for those associated with head protocols. CT protocol optimization is necessary for adult head and pediatric chest, HRCT-chest, abdominal, and pelvic protocols. The findings from this study are recommended for use as national DRLs in Turkey. PMID:26133189

  10. Variation of patient dose in head CT.

    PubMed

    Smith, A; Shah, G A; Kron, T

    1998-12-01

    CT dose varies with both equipment related and operator dependent factors. Thermoluminescence dosimetry (TLD) was employed in two phantoms to investigate the variation in absorbed dose for head CT scans, using a cylindrical head CT dose phantom. Dose profiles were plotted and the computed tomography dose index (CTDI) calculated for a single 10 mm thick slice on 14 CT scanners. An anthropomorphic head phantom was also scanned from the base-of-skull to the vertex using 10/10 mm slices. The absorbed dose measured at the centre of the scan series is reported (Dmid). The mean CTDIw for the 14 scanners was 60.0 mGy, while the mean Dmid was 45.8 mGy. Dmid better represents the absorbed dose in human tissues. The CTDIw and Dmid normalized to mAs varied by up to a factor of 2.2 for the different scanners. Equipment related factors contribute to such variations. However, variations due to operator dependent factors such as the choice of exposure factors, scanning protocol and positioning technique must also be considered. When such factors are taken into account the absorbed dose received by the patient can vary considerably, by as much as 16.2 for lens dose. Increased awareness of the factors influencing CT dose and the standardization of scanning protocols is recommended. PMID:10319004

  11. Flash imaging in dual source CT (DSCT)

    NASA Astrophysics Data System (ADS)

    Bruder, H.; Petersilka, M.; Mehldau, H.; Heidinger, W.; Allmendinger, T.; Schmidt, B.,; Raupach, R.; Thierfelder, C.,; Stierstorfer, K.; Flohr, T.

    2009-02-01

    We present new acquisition modes of a recently introduced dual-source computed tomography (DSCT) system equipped with two X-ray tubes and two corresponding detectors, mounted onto the rotating gantry with an angular offset of typically 90°. Due to the simultaneous acquisition of complementary data, the minimum exposure time is reduced by a factor of two compared to a single-source CT system (SSCT). The correspondingly improved temporal resolution is beneficial for cardiac CT. Also, maximum table feed per rotation in a spiral mode can be increased by a factor of 2 compared to SSCT, which provides benefits both for cardiac CT and non-cardiac CT. In an ECG-triggered mode the entire cardiac volume can be scanned within a fraction of one cardiac RR-cycle. At a rotation time of 0.28s using a detector with 64×0.6 mm beam collimation, the scan time of the entire heart is less than 0.3s at a temporal resolution of 75 ms. It will be shown, that the extremely fast cardiac scan reduces the patient dose to a theoretical lowest limit: for a 120 kV scan the dose level for a typical cardiac CT scan is well below 2 mSv. Using further protocol optimization (scan range adaptation, 100kV), the radiation dose can be reduced below 1mSv.

  12. Medipix-based Spectral Micro-CT.

    PubMed

    Yu, Hengyong; Xu, Qiong; He, Peng; Bennett, James; Amir, Raja; Dobbs, Bruce; Mou, Xuanqin; Wei, Biao; Butler, Anthony; Butler, Phillip; Wang, Ge

    2012-12-01

    Since Hounsfield's Nobel Prize winning breakthrough decades ago, X-ray CT has been widely applied in the clinical and preclinical applications - producing a huge number of tomographic gray-scale images. However, these images are often insufficient to distinguish crucial differences needed for diagnosis. They have poor soft tissue contrast due to inherent photon-count issues, involving high radiation dose. By physics, the X-ray spectrum is polychromatic, and it is now feasible to obtain multi-energy, spectral, or true-color, CT images. Such spectral images promise powerful new diagnostic information. The emerging Medipix technology promises energy-sensitive, high-resolution, accurate and rapid X-ray detection. In this paper, we will review the recent progress of Medipix-based spectral micro-CT with the emphasis on the results obtained by our team. It includes the state- of-the-art Medipix detector, the system and method of a commercial MARS (Medipix All Resolution System) spectral micro-CT, and the design and color diffusion of a hybrid spectral micro-CT. PMID:24194631

  13. A modified VMAT adaptive radiotherapy for nasopharyngeal cancer patients based on CT-CT image fusion

    PubMed Central

    2013-01-01

    Background To investigate the feasibility and benefits of a modified adaptive radiotherapy (ART) by replanning in the initial CT (iCT) with new contours from a repeat CT (rCT) based on CT-CT image fusion for nasopharyngeal cancer (NPC) patients underwent volumetric modulated arc radiotherapy (VMAT). Materials and methods Nine NPC patients underwent VMAT treatment with a rCT at 23rd fraction were enrolled in this study. Dosimetric differences for replanning VMAT plans in the iCT and in the rCT were compared. Volumetric and dosimetric changes of gross tumor volume (GTV) and organs at risk (OARs) of this modified ART were also investigated. Results No dosimetric differences between replanning in the iCT and in the rCT were observed. The average volume of GTV decreased from 78.83 ± 38.42 cm3 in the iCT to 71.44 ± 37.46 cm3 in the rCT, but with no significant difference (p = 0.42).The average volume of the left and right parotid decreased from 19.91 ± 4.89 cm3 and 21.58 ± 6.16 cm3 in the iCT to 11.80 ± 2.79 cm3 and 13.29 ± 4.17 cm3 in the rCT (both p < 0.01), respectively. The volume of other OARs did not shrink very much. No significant differences on PTVGTV and PTVCTV coverage were observed for replanning with this modified ART. Compared to the initial plans, the average mean dose of the left and right parotid after re-optimization were decreased by 62.5 cGy (p = 0.05) and 67.3 cGy (p = 0.02), respectively, and the V5 (the volume receiving 5 Gy) of the left and right parotids were decreased by 7.8% (p = 0.01) and 11.2% (p = 0.001), respectively. There was no significant difference on the dose delivered to other OARs. Conclusion Patients with NPC undergoing VMAT have significant anatomic and dosimetric changes to parotids. Repeat CT as an anatomic changes reference and re-optimization in the iCT based on CT-CT image fusion was accurate enough to identify the volume changes and to ensure safe dose to

  14. Small-animal CT: Its difference from, and impact on, clinical CT

    NASA Astrophysics Data System (ADS)

    Ritman, Erik L.

    2007-10-01

    For whole-body computed tomography (CT) images of small rodents, a voxel resolution of at least 10 -3 mm 3 is needed for scale-equivalence to that currently achieved in clinical CT scanners (˜1 mm 3) in adult humans. These "mini-CT" images generally require minutes rather than seconds to complete a scan. The radiation exposure resulting from these mini-CT scans, while higher than clinical CT scans, is below the level resulting in acute tissue damage. Hence, these scans are useful for performing clinical-type diagnostic and monitoring scans for animal models of disease and their response to treatment. "Micro-CT", with voxel size <10 -5 mm 3, has been useful for imaging isolated, intact organs at an almost cellular level of resolution. Micro-CT has the great advantage over traditional microscopic methods in that it generates detailed three-dimensional images in relatively large, opaque volumes such as an intact rodent heart or kidney. The radiation exposure needed in these scans results in acute tissue damage if used in living animals. Experience with micro-CT is contributing to exploration of new applications for clinical CT imaging by providing insights into different modes of X-ray image formation as follows: Spatial resolution should be sufficient to detect an individual Basic Functional Unit (BFU, the smallest collection of diverse cells, such as hepatic lobule, that behaves like the organ), which requires voxels ˜10 -3 mm 3 in volume, so that the BFUs can be counted. Contrast resolution sufficient to allow quantitation of: New microvascular growth, which manifests as increased tissue contrast due to X-ray contrast agent in those vessels' lumens during passage of injected contrast agent in blood. Impaired endothelial integrity which manifests as increased opacification and delayed washout of contrast from tissues. Discrimination of pathological accumulations of metals such as Fe and Ca, which occur in the arterial wall following hemorrhage or tissue damage

  15. Neck after total laryngectomy: CT study

    SciTech Connect

    DiSantis, D.J.; Balfe, D.M.; Hayden, R.E.; Sagel, S.S.; Sessions, D.; Lee, J.K.T.

    1984-12-01

    Computed tomographic scans in 23 patients who had undergone total laryngectomy were analyzed retrospectively to determine normal postoperative appearance and to evaluate the role of CT in assessing recurrent neoplasm. Nine patients without clinical evidence of recurrence illustrated the normal postoperative changes: a round or ovoid neopharynx connecting the base of the tongue with the cervical esophagus and intact fat planes surrounding the neopharynx, neurovascular bundles, and sternocleidomastoid muscles. In the 12 patients with recurrent neoplasm, the CT manifestations included masses involving the internal jugular lymph node chain, tracheostomy site, or paratracheal region. CT supplemented physical examination and indirect mirror examination, providing data regarding presence and extent of recurrent tumor and aiding in planning the mode and scope of therapy.

  16. CT densitometry of the lungs: Scanner performance

    SciTech Connect

    Kemerink, G.J.; Lamers, R.J.S.; Thelissen, G.R.P.; Engelshoven, J.M.A. van

    1996-01-01

    Our goal was to establish the reproducibility and accuracy of the CT scanner in densitometry of the lungs. Scanner stability was assessed by analysis of daily quality checks. Studies using a humanoid phantom and polyethylene foams for lung were performed to measure reproducibility and accuracy. The dependence of the CT-estimated density on reconstruction filter, zoom factor, slice thickness, table height, data truncation, and objects outside the scan field was determined. Stability of the system at air density was within {approx}1 HU and at water density within {approx}2 HU. Reproducibility and accuracy for densities found for lung were within 2-3%. Dependence on the acquisition and reconstruction parameters was neglible, with the exceptions of the ultra high resolution reconstruction algorithm in the case of emphysema, and objects outside the scan field. The performance of the CT scanner tested is quite adequate for densitometry of the lungs. 26 refs., 5 figs., 4 tabs.

  17. FDG-PET/CT in lymphoma

    PubMed Central

    D'souza, Maria M; Jaimini, Abhinav; Bansal, Abhishek; Tripathi, Madhavi; Sharma, Rajnish; Mondal, Anupam; Tripathi, Rajendra Prashad

    2013-01-01

    Lymphomas are a heterogeneous group of diseases that arise from the constituent cells of the immune system or from their precursors. 18F-fludeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is now the cornerstone of staging procedures in the state-of-the-art management of Hodgkin's disease and aggressive non-Hodgkin's lymphoma. It plays an important role in staging, restaging, prognostication, planning appropriate treatment strategies, monitoring therapy, and detecting recurrence. However, its role in indolent lymphomas is still unclear and calls for further investigational trials. The protean PET/CT manifestations of lymphoma necessitate a familiarity with the spectrum of imaging findings to enable accurate diagnosis. A meticulous evaluation of PET/CT findings, an understanding of its role in the management of lymphomas, and knowledge of its limitations are mandatory for the optimal utilization of this technique. PMID:24604942

  18. CT measurments of cranial growth: normal subjects

    SciTech Connect

    Hahn, F.J.; Chu, W.K.; Cheung, J.Y.

    1984-06-01

    Growth patterns of the cranium measured directly as head circumference have been well documented. With the availability of computed tomography (CT) , cranial dimensions can be obtained easily. The objective of this project was to establish the mean values and their normal variance of CT cranial area of subjects at different ages. Cranial area and its long and short axes were measured on CT scans for 215 neurologic patients of a wide age range who presented no evidence of abnormal growth of head size. Growth patterns of the cranial area as well as the numeric product of it linear dimensions were determined via a curve fitting process. The patterns resemble that of the head circumference growth chart, with the most rapid growth observed in the first 12 months of age and reaching full size during adolescence.

  19. Hybrid SPECT/CT imaging in neurology.

    PubMed

    Ciarmiello, Andrea; Giovannini, Elisabetta; Meniconi, Martina; Cuccurullo, Vincenzo; Gaeta, Maria Chiara

    2014-01-01

    In recent years, the SPECT/CT hybrid modality has led to a rapid development of imaging techniques in nuclear medicine, opening new perspectives for imaging staff and patients as well. However, while, the clinical role of positron emission tomography-computed tomography (PET-CT) is well consolidated, the diffusion and the consequent value of single-photon emission tomography-computed tomography (SPECT-CT) has yet to be weighed, Hence, there is a need for a careful analysis, comparing the "potential" benefits of the hybrid modality with the "established" ones of the standalone machine. The aim of this article is to analyze the impact of this hybrid tool on the diagnosis of diseases of the central nervous system, comparing strengths and weaknesses of both modalities through the use of SWOT analysis. PMID:25143053

  20. CT image registration in sinogram space

    SciTech Connect

    Mao Weihua; Li Tianfang; Wink, Nicole; Xing Lei

    2007-09-15

    Object displacement in a CT scan is generally reflected in CT projection data or sinogram. In this work, the direct relationship between object motion and the change of CT projection data (sinogram) is investigated and this knowledge is applied to create a novel algorithm for sinogram registration. Calculated and experimental results demonstrate that the registration technique works well for registering rigid 2D or 3D motion in parallel and fan beam samplings. Problem and solution for 3D sinogram-based registration of metallic fiducials are also addressed. Since the motion is registered before image reconstruction, the presented algorithm is particularly useful when registering images with metal or truncation artifacts. In addition, this algorithm is valuable for dealing with situations where only limited projection data are available, making it appealing for various applications in image guided radiation therapy.

  1. Cherubism: panoramic and CT features in adults

    PubMed Central

    Redfors, M; Jensen, J L; Storhaug, K; Prescott, T; Larheim, T A

    2013-01-01

    Objectives: To describe the panoramic radiographic and CT features of cherubism in an unselected series of 15 adults. Methods: In this cross-sectional study, 15 individuals aged 29–84 years with familial non-syndromal molecularly confirmed cherubism were examined with panoramic radiography and CT. Bone abnormalities were analysed and described. Results: 11 (73%) of the 15 adults had mandibular abnormalities. These abnormalities ranged from subtly detectable to severe, and were less prevalent and expansive but could be rather similar to the characteristic image features in children. Unilocular radiolucencies were more common than multilocular radiolucencies, and a specific feature of these abnormalities was that they were exclusively found in the anterior mandible. Conclusions: The radiographic and CT abnormalities of cherubism in adults were frequent and extremely heterogeneous, with some distinct features. PMID:24048692

  2. Vertebral osteomyelitis: disk hypodensity on CT

    SciTech Connect

    Larde, D.; Mathieu, D.; Frija, J.; Gaston, A.; Vasile, N.

    1982-11-01

    The importance and role of computed tomography (CT) are discussed on the basis of 36 cases of vertebral osteomyelitis. The bone images themselves, the detection of lumbar disk hypodensity, and the exploration of soft paraspinal regions in the search for an abscess are factors that contribute to the superiority of this method in difficult cases. In cases where the diagnosis is already known, CT offers an excellent method to assess the extent of the lesions. Its accuracy, coupled with its rapidity and noninvasive nature, affects the role of conventional tomography, a method that is incomplete and involves higher radiation doses. CT offers an excellent method for follow-up after treatment of vertebral osteomyelitis.

  3. Bariatric CT Imaging: Challenges and Solutions.

    PubMed

    Fursevich, Dzmitry M; LiMarzi, Gary M; O'Dell, Matthew C; Hernandez, Manuel A; Sensakovic, William F

    2016-01-01

    The obesity epidemic in the adult and pediatric populations affects all aspects of health care, including diagnostic imaging. With the increasing prevalence of obese and morbidly obese patients, bariatric computed tomographic (CT) imaging is becoming common in day-to-day radiology practice, and a basic understanding of the unique problems that bariatric patients pose to the imaging community is crucial in any setting. Because larger patients may not fit into conventional scanners, having a CT scanner with an adequate table load limit, a large gantry aperture, a large scan field of view, and a high-power generator is a prerequisite for bariatric imaging. Iterative reconstruction methods, high tube current, and high tube voltage can reduce the image noise that is frequently seen in bariatric CT images. Truncation artifacts, cropping artifacts, and ring artifacts frequently complicate the interpretation of CT images of larger patients. If recognized, these artifacts can be easily reduced by using the proper CT equipment, scan acquisition parameters, and postprocessing options. Lastly, because of complex contrast material dynamics, contrast material-enhanced studies of bariatric patients require special attention. Understanding how the rate of injection, the scan timing, and the total mass of iodine affect vascular and parenchymal enhancement will help to optimize contrast-enhanced studies in the bariatric population. This article familiarizes the reader with the challenges that are frequently encountered at CT imaging of bariatric patients, beginning with equipment selection and ending with a review of the most commonly encountered obesity-related artifacts and the technical considerations in the acquisition of contrast-enhanced images. (©)RSNA, 2016. PMID:27232505

  4. Frontoethmoidal Mucoceles: CT and MRI Evaluation.

    PubMed

    Tsitouridis, I; Michaelides, M; Bintoudi, A; Kyriakou, V

    2007-10-31

    Paranasal sinus mucocele is an expanded, airless, mucus-filled sinus caused by obstruction of the sinus ostium. It is a benign slow growing epithelial lined lesion, bulging against adjacent anatomical structures, without infiltrating them. The purpose of our study is to describe the CT and MR findings in 19 patients (ten women, nine men, 18-72 years, mean age: 48.1) with surgically confirmed frontoethmoidal mucoceles between 1999-2005. CT scans displayed mucoceles as non enhancing soft tissue density lesions, generally isodense to the brain parenchyma, expanding the sinuses in most cases, eroding adjacent bones and extending intraorbitally or intracranially. Signal intensity in T2WI and T1WI MR images varied, but generally lesions had high signal intensity in T2WI and low to intermediate signal intensity in T1WI. Some of the lesions demonstrated regular linear peripheral enhancement after administration of contrast medium. The causes of mucoceles included mucosal thickening from chronic sinusitis, adhesions from previous operation in the nasal cavity, previous trauma, small nasal polyps and a small osteoma, while in six patients (31.5%) the cause of the mucocele remained unrecognized even after surgery. No underlying malignant tumor was found in any of the cases as the cause of obstruction. CT and MRI established the correct diagnosis in all patients. CT was more sensitive in determining bone erosions, while MRI had the advantage of multiplanar imaging and was much more sensitive for differentiating mucocele from a tumor on the basis of MR signal intensity characteristics. In conclusion, CT and MRI are the methods of choice for diagnosing mucoceles of the paranasal sinuses and are of major importance for the treatment plan. Each method seems to have its own advantages and should be used as complementary investigations of sinonasal pathology. Enhanced CT scan should only be performed in the absence or contraindication for enhanced MR imaging. PMID:24299951

  5. Trapping volumetric measurement by multidetector CT in chronic obstructive pulmonary disease: Effect of CT threshold

    SciTech Connect

    Wang, Xiaohua; Yuan, Huishu; Duan, Jianghui; Du, Yipeng; Shen, Ning; He, Bei

    2013-08-15

    Purpose: The purpose of this study was to evaluate the effect of various computed tomography (CT) thresholds on trapping volumetric measurements by multidetector CT in chronic obstructive pulmonary disease (COPD).Methods: Twenty-three COPD patients were scanned with a 64-slice CT scanner in both the inspiratory and expiratory phase. CT thresholds of −950 Hu in inspiration and −950 to −890 Hu in expiration were used, after which trapping volumetric measurements were made using computer software. Trapping volume percentage (Vtrap%) under the different CT thresholds in the expiratory phase and below −950 Hu in the inspiratory phase was compared and correlated with lung function.Results: Mean Vtrap% was similar under −930 Hu in the expiratory phase and below −950 Hu in the inspiratory phase, being 13.18 ± 9.66 and 13.95 ± 6.72 (both lungs), respectively; this difference was not significant (P= 0.240). Vtrap% under −950 Hu in the inspiratory phase and below the −950 to −890 Hu threshold in the expiratory phase was moderately negatively correlated with the ratio of forced expiratory volume in one second to forced vital capacity and the measured value of forced expiratory volume in one second as a percentage of the predicted value.Conclusions: Trapping volumetric measurement with multidetector CT is a promising method for the quantification of COPD. It is important to know the effect of various CT thresholds on trapping volumetric measurements.

  6. Multisegmented ion chamber for CT scanner dosimetry

    SciTech Connect

    Moore, M.M.; Cacak, R.K.; Hendee, W.R.

    1981-01-01

    A multisegmented, ionization chamber capable of determining dosimetric profiles from a CT scanner has been developed and tested. The chamber consists of a number of 2 mm wide electrically isolated segments from which ionization currents may be measured. Presented here are the performance characteristics of the chamber including energy response, dose linearity, and corrections for ''cross talk'' between segments. Sample dosimetric profiles are depicted for 3 and 6 mm nominal beam widths at two locations in a dosimetric phantom positioned in the x-ray beam of a fourth generation CT scanner. The results agree well with the conventional method of obtaining dosimetry measurements with TLD chips.

  7. High resolution extremity CT for biomechanics modeling

    SciTech Connect

    Ashby, A.E.; Brand, H.; Hollerbach, K.; Logan, C.M.; Martz, H.E.

    1995-09-23

    With the advent of ever more powerful computing and finite element analysis (FEA) capabilities, the bone and joint geometry detail available from either commercial surface definitions or from medical CT scans is inadequate. For dynamic FEA modeling of joints, precise articular contours are necessary to get appropriate contact definition. In this project, a fresh cadaver extremity was suspended in parafin in a lucite cylinder and then scanned with an industrial CT system to generate a high resolution data set for use in biomechanics modeling.

  8. IV Leiomyomatosis on FDG PET/CT.

    PubMed

    Jin, Xiaona; Li, Fang; Lu, Zhaohui; Cheng, Wuying

    2016-07-01

    A 48-year-old woman presented with a 2-month history of right lower extremity edema. Clinical examination only showed right lower limb swelling. Routine laboratory examination revealed no abnormal results. Abdominal ultrasonography identified uterine leiomyoma and soft tissue masses. An abdominal CT demonstrated a continuous mass extending from the right internal and external iliac vein into the common iliac vein and inferior vena cava. To distinguish the mass from malignancy, the patient underwent PET/CT scan which showed increased FDG activity in the mass. However, histopathological examination proved the mass to be IV leiomyomatosis. PMID:26914578

  9. Intracerebral pneumatoceles following facial trauma: CT findings

    SciTech Connect

    Mendelsohn, D.B.; Hertzanu, Y.

    1985-01-01

    Three patients with delayed frontal intracerebral pneumatoceles following facial injury are presented. In one patient an unusual appearance of bilateral and symmetrical frontal lobe pneumatoceles was demonstrated. While diagnosis is not difficult on routine radiographs, CT is valuable for determining effects on the brain and clearly delineating the fracture site; CT shows the location of the pneumatocele and may show an associated air-fluid level, mass effect or surrounding edema, or rim enhancement following administration of contrast material. The radiological appearances in conjunction with the clinical findings are highly characteristic and should not be mistaken for gas-forming cerebral abscesses.

  10. Borne identity: CT imaging of vascular infections.

    PubMed

    Huang, Jessica S; Ho, Alexander S; Ahmed, Absar; Bhalla, Sanjeev; Menias, Christine O

    2011-08-01

    Vascular infections present in a multitude of ways with computed tomography (CT) aiding in the diagnosis of many of the uncommon vascular infections, which are equally dangerous and carry severe life-threatening consequences if untreated from a delay in diagnosis. This pictorial review aims to discuss and illustrate the CT findings of the following vascular infections including aortitis, mycotic aneurysms, infective endocarditis, septic thrombophlebitis in the chest and abdomen, and Kawasaki disease. Recognition and prompt diagnosis of these uncommon vascular infections are critical to the initiation of the appropriate management and therapy. PMID:21424803

  11. CT of nontraumatic thoracic aortic emergencies.

    PubMed

    Bhalla, Sanjeev; West, O Clark

    2005-10-01

    Computed tomography (CT), especially multidetector row CT (MDCT), is often the preferred imaging test used for evaluation of nontraumatic thoracic aortic abnormalities. Unenhanced images, usually followed by contrast-enhanced arterial imaging, allow for rapid detailed aortic assessment. Understanding the spectrum of acute thoracic aortic conditions which may present similarly (aortic dissection, aneurysm rupture, penetrating atherosclerotic ulcer, intramural hematoma) will ensure that patients are diagnosed and treated appropriately. Familiarity with imaging protocols and potential mimics will prevent confusion of normal anatomy and variants with aortic disease. PMID:16274000

  12. CT of acute abdominal aortic disorders.

    PubMed

    Bhalla, Sanjeev; Menias, Christine O; Heiken, Jay P

    2003-11-01

    Aortic aneurysm rupture, aortic dissection, PAU, acute aortic occlusion, traumatic aortic injury, and aortic fistula represent acute abdominal aortic conditions. Because of its speed and proximity to the emergency department, helical CT is the imaging test of choice for these conditions. MR imaging also plays an important role in the imaging of aortic dissection and PAU, particularly when the patient is unable to receive intravenous contrast material. In this era of MDCT, conventional angiography is used as a secondary diagnostic tool to clarify equivocal findings on cross-sectional imaging. Ultrasound is helpful when CT is not readily available and the patient is unable or too unstable to undergo MR imaging. PMID:14661663

  13. CT of perineural tumor extension: pterygopalatine fossa

    SciTech Connect

    Curtin, H.D.; Williams, R.; Johnson, J.

    1985-01-01

    Tumors of the oral cavity and paranasal sinuses can spread along nerves to areas apparently removed from the primary tumor. In tumors of the palate, sinuses, and face, this perineural spread usually involves the maxillary division of the trigeminal nerve. The pterygopalatine fossa is a pathway of the maxillary nerve and becomes a key landmark in the detection of neural metastasis by computed tomography (CT). Obliteration of the fat in the fossa suggests pathology. Case material illustrating neural extension is presented and the CT findings are described.

  14. Temporomandibular joint internal derangements: CT diagnosis

    SciTech Connect

    Helms, C.A.; Vogler, J.B. III; Morrish, R.B. Jr.; Goldman, S.M.; Capra, R.E.; Proctor, E.

    1984-08-01

    Two hundred patients with suspected displaced temporomandibular joint meniscus were studied with computed tomography. In 75 cases confirmation of the CT diagnosis was subsequently obtained via surgery or arthrography; correlation was found in 73 cases (97%), with one false-negative and one false-positive examination. When meniscus displacement was graded as mild, moderate, or severe, those cases diagnosed as moderate or severe were more likely to require surgery. The technique and interpretation of this technique is described; in most cases CT can replace arthrography in diagnosing displaced temporomandibular joint menisci.

  15. [Performance evaluation for CT-AEC(CT automatic exposure control)systems].

    PubMed

    Muramatsu, Yoshihisa; Ikeda, Shu; Osawa, Kazuaki; Sekine, Ryo; Niwa, Nobuyuki; Terada, Masami; Keat, Nicholas; Miyazaki, Shigeru

    2007-05-20

    Although many current CT scanners incorporate CT-AEC, performance evaluation is not standardized. This study evaluates the performance of the latest CT-AEC of each manufacturer with the aim of establishing a standard CT-AEC performance evaluation method. The design of the phantoms was based upon the operation characteristics of different CT-AECs. A cone, an ellipse, a variable-shaped ellipse, stepped phantoms, and their analysis software were devised and carried out the field test. The targets were LightSpeed VCT 64 with 2D and 3D Auto mA(GE), Aquilion 64M with Real-EC and Volume-EC(Toshiba), Sensation 64 with CARE Dose and CARE Dose 4D(Siemens), and Bulliance 16P with Dose Right(Philips). Data was acquired while varying the typical abdominal CT(with CT-AEC)scanning conditions (120 kV, 5 mm slice, standard function for abdomen, scanning range 200 mm). The acquired images were converted to the DICOM format and image noise(SD) was calculated using dedicated software. All 4 CT-AECs reduced exposure dose. For GE and Toshiba, image noise was constant and met the target. For Siemens, noise was independent of phantom shape but varied uniformly with phantom size. For Philips, noise varied with phantom size and shape, and variation degree depended on phantom thickness in scanogram direction. The results reflect the basic concept and performance characteristics of the methods. Standardization of CT-AEC performance evaluation is possible using these phantoms. PMID:17538218

  16. 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.

  17. Method for transforming CT images for attenuation correction in PET/CT imaging

    SciTech Connect

    Carney, Jonathan P.J.; Townsend, David W.; Rappoport, Vitaliy; Bendriem, Bernard

    2006-04-15

    A tube-voltage-dependent scheme is presented for transforming Hounsfield units (HU) measured by different computed tomography (CT) scanners at different x-ray tube voltages (kVp) to 511 keV linear attenuation values for attenuation correction in positron emission tomography (PET) data reconstruction. A Gammex 467 electron density CT phantom was imaged using a Siemens Sensation 16-slice CT, a Siemens Emotion 6-slice CT, a GE Lightspeed 16-slice CT, a Hitachi CXR 4-slice CT, and a Toshiba Aquilion 16-slice CT at kVp ranging from 80 to 140 kVp. All of these CT scanners are also available in combination with a PET scanner as a PET/CT tomograph. HU obtained for various reference tissue substitutes in the phantom were compared with the known linear attenuation values at 511 keV. The transformation, appropriate for lung, soft tissue, and bone, yields the function 9.6x10{sup -5}{center_dot}(HU+1000) below a threshold of {approx}50 HU and a{center_dot}(HU+1000)+b above the threshold, where a and b are fixed parameters that depend on the kVp setting. The use of the kVp-dependent scaling procedure leads to a significant improvement in reconstructed PET activity levels in phantom measurements, resolving errors of almost 40% otherwise seen for the case of dense bone phantoms at 80 kVp. Results are also presented for patient studies involving multiple CT scans at different kVp settings, which should all lead to the same 511 keV linear attenuation values. A linear fit to values obtained from 140 kVp CT images using the kVp-dependent scaling plotted as a function of the corresponding values obtained from 80 kVp CT images yielded y=1.003x-0.001 with an R{sup 2} value of 0.999, indicating that the same values are obtained to a high degree of accuracy.

  18. Patient-specific CT dose determination from CT images using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Liang, Qing

    Radiation dose from computed tomography (CT) has become a public concern with the increasing application of CT as a diagnostic modality, which has generated a demand for patient-specific CT dose determinations. This thesis work aims to provide a clinically applicable Monte-Carlo-based CT dose calculation tool based on patient CT images. The source spectrum was simulated based on half-value layer measurements. Analytical calculations along with the measured flux distribution were used to estimate the bowtie-filter geometry. Relative source output at different points in a cylindrical phantom was measured and compared with Monte Carlo simulations to verify the determined spectrum and bowtie-filter geometry. Sensitivity tests were designed with four spectra with the same kVp and different half-value layers, and showed that the relative output at different locations in a phantom is sensitive to different beam qualities. An mAs-to-dose conversion factor was determined with in-air measurements using an Exradin A1SL ionization chamber. Longitudinal dose profiles were measured with thermoluminescent dosimeters (TLDs) and compared with the Monte-Carlo-simulated dose profiles to verify the mAs-to-dose conversion factor. Using only the CT images to perform Monte Carlo simulations would cause dose underestimation due to the lack of a scatter region. This scenario was demonstrated with a cylindrical phantom study. Four different image extrapolation methods from the existing CT images and the Scout images were proposed. The results show that performing image extrapolation beyond the scan region improves the dose calculation accuracy under both step-shoot scan mode and helical scan mode. Two clinical studies were designed and comparisons were performed between the current CT dose metrics and the Monte-Carlo-based organ dose determination techniques proposed in this work. The results showed that the current CT dosimetry failed to show dose differences between patients with the same

  19. Comparison of CT and MR-CT Fusion for Prostate Post-Implant Dosimetry

    SciTech Connect

    Maletz, Kristina L.; Ennis, Ronald D.; Ostenson, Jason; Pevsner, Alexander; Kagen, Alexander; Wernick, Iddo

    2012-04-01

    Purpose: The use of T2 MR for postimplant dosimetry (PID) after prostate brachytherapy allows more anatomically accurate and precise contouring but does not readily permit seed identification. We developed a reproducible technique for performing MR-CT fusion and compared the resulting dosimetry to standard CT-based PID. Methods and Materials: CT and T1-weighted MR images for 45 patients were fused and aligned based on seed distribution. The T2-weighted MR image was then fused to the aligned T1. Reproducibility of the fusion technique was tested by inter- and intraobserver variability for 13 patients. Dosimetry was computed for the prostate as a whole and for the prostate divided into anterior and posterior sectors of the base, mid-prostate, and apex. Results: Inter- and intraobserver variability for the fusion technique showed less than 1% variation in D90. MR-CT fusion D90 and CT D90 were nearly equivalent for the whole prostate, but differed depending on the identification of superior extent of the base (p = 0.007) and on MR/CT prostate volume ratio (p = 0.03). Sector analysis showed a decrease in MR-CT fusion D90 in the anterior base (ratio 0.93 {+-}0.25, p < 0.05) and an increase in MR-CT fusion D90 in the apex (p < 0.05). The volume of extraprostatic tissue encompassed by the V100 is greater on MR than CT. Factors associated with this difference are the MR/CT volume ratio (p < 0.001) and the difference in identification of the inferior extent of the apex (p = 0.03). Conclusions: We developed a reproducible MR-CT fusion technique that allows MR-based dosimetry. Comparing the resulting postimplant dosimetry with standard CT dosimetry shows several differences, including adequacy of coverage of the base and conformity of the dosimetry around the apex. Given the advantage of MR-based tissue definition, further study of MR-based dosimetry is warranted.

  20. Empirical beam hardening correction (EBHC) for CT

    SciTech Connect

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc

    2010-10-15

    Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern

  1. 122. Four Blade Semaphore Tower. Groton, New London Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    122. Four Blade Semaphore Tower. Groton, New London Co., CT. Sec. 4215, MP 124.60. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  2. 52. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  3. 49. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  4. 53. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    53. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  5. 51. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  6. 50. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  7. 57. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    57. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  8. 55. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    55. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  9. 56. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  10. 54. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. Housatonic River Bridge. Stratford, Fairfield Co., CT. Sec. 9108, MP 60.44. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  11. 119. Thames River Bridge. New London, New London Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    119. Thames River Bridge. New London, New London Co., CT. Sec. 4215, MP 124.09. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  12. 118. Thames River Bridge. New London, New London Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    118. Thames River Bridge. New London, New London Co., CT. Sec. 4215, MP 124.09. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  13. 117. Thames River Bridge. New London, New London Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    117. Thames River Bridge. New London, New London Co., CT. Sec. 4215, MP 124.09. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  14. 116. Thames River Bridge. New London, New London Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    116. Thames River Bridge. New London, New London Co., CT. Sec. 4215, MP 124.09. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  15. 20. Typical circuit breaker gantry. Norwalk, Fairfield Co., CT. Sec. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Typical circuit breaker gantry. Norwalk, Fairfield Co., CT. Sec. 9108, MP 41.20. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  16. Doctors Should Bone Up on CT Scan Cancer Risks

    MedlinePlus

    ... fullstory_159909.html Doctors Should Bone Up on CT Scan Cancer Risks Many not aware of exact radiation ... July 15, 2016 (HealthDay News) -- Doctors routinely order CT scans as diagnostic tools. But many are ill-informed ...

  17. 38. Saga Interlocking Tower. Greens Farms, Fairfield Co., CT. Sec. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. Saga Interlocking Tower. Greens Farms, Fairfield Co., CT. Sec. 9108, MP 47.00. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  18. 37. Saga Interlocking Tower. Greens Farms, Fairfield Co., CT. Sec. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. Saga Interlocking Tower. Greens Farms, Fairfield Co., CT. Sec. 9108, MP 47.00. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  19. 111. Shaws Cove Bridge. New London, New London Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    111. Shaws Cove Bridge. New London, New London Co., CT. Sec. 4209, MP 122.65. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  20. Anatomy of the ethmoid: CT, endoscopic, and macroscopic

    SciTech Connect

    Terrier, F.; Weber, W.; Ruefenacht, D.; Porcellini, B.

    1985-03-01

    The authors illustrate the normal CT anatomy of the ethmoid region and correlate it with the endoscopic and macroscopic anatomy to define landmarks that can be recognized on CT and during endoscopically controlled transnasal ethmoidectomy.

  1. 124. Mystic River Bridge. Mystic, New London Co., CT. Sec. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    124. Mystic River Bridge. Mystic, New London Co., CT. Sec. 4215, MP 132.16. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  2. 123. Mystic River Bridge. Mystic, New London Co., CT. Sec. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    123. Mystic River Bridge. Mystic, New London Co., CT. Sec. 4215, MP 132.16. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  3. CT Scans - Multiple Languages: MedlinePlus

    MedlinePlus

    ... List of All Topics All CT Scans - Multiple Languages To use the sharing features on this page, please enable JavaScript. Arabic (العربية) Chinese - Simplified (简体中文) Chinese - Traditional (繁體中文) French ( ...

  4. FDG PET/CT of Intercostal Schwannoma.

    PubMed

    Wang, Si-Yun; Luo, Dong-Lan; Chen, Gang; Liu, En-Tao; Wang, Shu-Xia

    2016-06-01

    Intercostal schwannoma is rare. We report FDG PET/CT findings of intercostal schwannoma in a 66-year-old woman. The tumor contains both solid and cystic components with intense FDG activity in the solid component. Postsurgical pathology diagnosis revealed schwannoma. PMID:26859215

  5. 75 FR 32821 - Connecticut Disaster #CT-00014

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-09

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00014 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Connecticut...

  6. 76 FR 13443 - Connecticut Disaster #CT-00019

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    ... From the Federal Register Online via the Government Publishing Office ] SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00019 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  7. 77 FR 67856 - Connecticut Disaster #CT-00028

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-14

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00028 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Connecticut...

  8. 76 FR 56858 - Connecticut Disaster #CT-00024

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-14

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00024 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Connecticut...

  9. 75 FR 22871 - Connecticut Disaster # CT-00015

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00015 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  10. 75 FR 65390 - Connecticut Disaster #CT-00016

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-22

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00016 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Connecticut dated...

  11. 76 FR 74115 - Connecticut Disaster # CT-00026

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-30

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  12. 78 FR 20370 - Connecticut Disaster # CT-00031

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-04

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00031 AGENCY: U.S. Small Business Administration. ACTION: Notice SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  13. 77 FR 71665 - Connecticut Disaster #CT-00029

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00029 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  14. 78 FR 11724 - Connecticut Disaster #CT-00030

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-19

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00030 AGENCY: Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Connecticut dated...

  15. Regularized CT reconstruction on unstructured grid

    NASA Astrophysics Data System (ADS)

    Chen, Yun; Lu, Yao; Ma, Xiangyuan; Xu, Yuesheng

    2016-04-01

    Computed tomography (CT) is an ill-posed problem. Reconstruction on unstructured grid reduces the computational cost and alleviates the ill-posedness by decreasing the dimension of the solution space. However, there was no systematic study on edge-preserving regularization methods for CT reconstruction on unstructured grid. In this work, we propose a novel regularization method for CT reconstruction on unstructured grid, such as triangular or tetrahedral meshes generated from the initial images reconstructed via analysis reconstruction method (e.g., filtered back-projection). The proposed regularization method is modeled as a three-term optimization problem, containing a weighted least square fidelity term motivated by the simultaneous algebraic reconstruction technique (SART). The related cost function contains two non-differentiable terms, which bring difficulty to the development of the fast solver. A fixed-point proximity algorithm with SART is developed for solving the related optimization problem, and accelerating the convergence. Finally, we compare the regularized CT reconstruction method to SART with different regularization methods. Numerical experiments demonstrated that the proposed regularization method on unstructured grid is effective to suppress noise and preserve edge features.

  16. 76 FR 56854 - Connecticut Disaster #CT-00023

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-14

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster CT-00023 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  17. Pitfalls in PET/CT imaging

    NASA Astrophysics Data System (ADS)

    Rondogianni, Ph; Papathanasiou, N.; Giannopoulou, Ch

    2011-09-01

    PET with 2-[fluorine 18] fluoro-2-deoxy-d-glucose (FDG), has been a clinical tool for the evaluation of various cancers providing valuable metabolic information clinically helpful in the diagnosis, initial staging, therapy monitoring and restaging. However, FDG is not specific for neoplastic processes. Unless anatomic correlation is available to delineate normal structures, pathologic sites of FDG accumulation can easily be confused with normal physiological uptake, leading to false-positive or false-negative findings. Coregistration of PET scans (functional and morphologic information) with computed tomographic (CT) scans (anatomic information) using a combined PET-CT scanner improves the overall sensitivity and specificity of information provided by PET or CT alone. In this paper, we discuss the probable causes of false negative images and pitfalls due to technical reasons, inflammatory processes or benign lesions as well as the utility of PET-CT in differentiating malignant from inflammatory and benign processes, since in some cases such differentiation cannot be made, with certainty, using FDG PET alone.

  18. ctDNA DLBCL Detection Lancet Oncology

    Cancer.gov

    Measurement of circulating tumor DNA in blood can be used to detect disease recurrence in patients with a curable form of cancer known as diffuse large B-cell lymphoma (DLBCL). In most patients, measurement of ctDNA enabled detection of microscopic diseas

  19. BENCHMARKING OF CT FOR PATIENT EXPOSURE OPTIMISATION.

    PubMed

    Racine, Damien; Ryckx, Nick; Ba, Alexandre; Ott, Julien G; Bochud, François O; Verdun, Francis R

    2016-06-01

    Patient dose optimisation in computed tomography (CT) should be done using clinically relevant tasks when dealing with image quality assessments. In the present work, low-contrast detectability for an average patient morphology was assessed on 56 CT units, using a model observer applied on images acquired with two specific protocols of an anthropomorphic phantom containing spheres. Images were assessed using the channelised Hotelling observer (CHO) with dense difference of Gaussian channels. The results were computed by performing receiver operating characteristics analysis (ROC) and using the area under the ROC curve (AUC) as a figure of merit. The results showed a small disparity at a volume computed tomography dose index (CTDIvol) of 15 mGy depending on the CT units for the chosen image quality criterion. For 8-mm targets, AUCs were 0.999 ± 0.018 at 20 Hounsfield units (HU) and 0.927 ± 0.054 at 10 HU. For 5-mm targets, AUCs were 0.947 ± 0.059 and 0.702 ± 0.068 at 20 and 10 HU, respectively. The robustness of the CHO opens the way for CT protocol benchmarking and optimisation processes. PMID:26940439

  20. Gallbladder Tuberculosis: CT Findings with Histopathologic Correlation

    PubMed Central

    Xu, Xiu-Fang; Qiu, Ling-Ling; Shen, Jian; Dong, Fei; Chen, Ying

    2011-01-01

    Objective We wanted to describe the computed tomography (CT) findings of gallbladder tuberculosis (TB) and to correlate them with pathologic findings. Materials and Methods There were seven patients (M:F = 3:4; mean age, 46.3 years; age range, 32 to 78 years) in whom gallbladder TB was eventually diagnosed. All of them underwent cross-sectional imaging with CT, a pathologic examination and a retrospective review. CT imaging evaluation was done in each case, including the findings of a mass versus nodule, wall thickening (uniform or irregular) and the enhancement patterns (homogeneous or heterogeneous). Results All the cases of gallbladder TB revealed the following three different CT findings: micronodular lesion of the gallbladder wall (n = 1), a thickened wall (n = 4) and a gallbladder mass (n = 2). There were three cases of homogeneous enhancement of the lesions, including homogeneous enhancement with nodular lesion, homogeneous uniform thickness enhancement and homogeneous thickness enhancement in one case each, and these cases pathology showed tuberculous granuloma with a little caseating necrosis in one case and tuberculous granuloma with rich fibrous tissue, but little or no evident caseating necrosis in two cases. Four cases of heterogeneous enhancement of the lesions, including heterogeneous uniform-thickness enhancement in two cases, heterogeneous enhancement with a local mass lesion in one case and heterogeneous enhancement with a mass that replaced the gallbladder in one case; in these cases, pathology showed tuberculous granuloma with marked caseation or liquefaction necrosis in three cases and tuberculous granuloma by fibrous and calcifications accompanied by caseating necrosis in one case. Among the seven cases of gallbladder TB, six cases were accompanied by abdominal extra-gallbladder TB, including abdominal lymph node TB in five cases and hepatic TB in four cases. Conclusion Gallbladder TB has various CT manifestations, and the enhanced CT findings

  1. Systematic scanner variability of patient CT attenuation measurements

    NASA Astrophysics Data System (ADS)

    Judy, Philip F.; Nawfel, Richard D.; Silverman, Stuart G.

    2009-02-01

    CT numbers of the spleen, liver, and trachea air were measured from non-contrast images obtained from 4-channel and 64-channel scanners from the same vendor. Image sections of 1 mm and 5 mm were reconstructed using smooth and sharp kernels. For spleen and liver, no significant differences associated with the variations in kernels or slice thickness could be demonstrated. The increase of the number of channels from 4 to 64 lowered the spleen CT numbers from 53 HU to 43 HU (p <0.00001). The 4-channel spleen CT numbers slightly increased as function of patient size, while the 64-channel CT numbers decreased as function of patient size. Linear regressions predicted for 40-cm patients the spleen 64-channel CT values were 23 HU lower than 4-channel CT numbers. The smooth kernel, 4-channel trachea air CT numbers had mean of -1004 +/-4.8 HU and the 64-channel trachea air CT numbers had a mean of -989+/-4.5 HU. The patient-size dependencies suggest that the CT attenuation variation is associated with increased scatter in 64-channel MSCT. Using CT number to distinguish solid lesions from cysts or quantitative evaluation of COPD disease using CT images may be complicated by inconsistencies between CT scanners.

  2. Cone beam CT guidance provides superior accuracy for complex needle paths compared with CT guidance

    PubMed Central

    Braak, S J; Fütterer, J J; van Strijen, M J L; Hoogeveen, Y L; de Lange, F; Schultze Kool, L J

    2013-01-01

    Objective: To determine the accuracy of cone beam CT (CBCT) guidance and CT guidance in reaching small targets in relation to needle path complexity in a phantom. Methods: CBCT guidance combines three-dimensional CBCT imaging with fluoroscopy overlay and needle planning software to provide real-time needle guidance. The accuracy of needle positioning, quantified as deviation from a target, was assessed for inplane, angulated and double angulated needle paths. Four interventional radiologists reached four targets along the three paths using CBCT and CT guidance. Accuracies were compared between CBCT and CT for each needle path and between the three approaches within both modalities. The effect of user experience in CBCT guidance was also assessed. Results: Accuracies for CBCT were significantly better than CT for the double angulated needle path (2.2 vs 6.7 mm, p<0.001) for all radiologists. CBCT guidance showed no significant differences between the three approaches. For CT, deviations increased with increasing needle path complexity from 3.3 mm for the inplane placements to 4.4 mm (p=0.007) and 6.7 mm (p<0.001) for the angulated and double angulated CT-guided needle placements, respectively. For double angulated needle paths, experienced CBCT users showed consistently higher accuracies than trained users [1.8 mm (range 1.2–2.2) vs 3.3 mm (range 2.1–7.2) deviation from target, respectively; p=0.003]. Conclusion: In terms of accuracy, CBCT is the preferred modality, irrespective of the level of user experience, for more difficult guidance procedures requiring double angulated needle paths as in oncological interventions. Advances in knowledge: Accuracy of CBCT guidance has not been discussed before. CBCT guidance allows accurate needle placement irrespective of needle path complexity. For angulated and double-angulated needle paths, CBCT is more accurate than CT guidance. PMID:23913308

  3. FDG PET/CT diagnosis of hepatic lymphoma mimicking focal fatty infiltration on CT

    PubMed Central

    Lin, Eugene; Lee, Marie; Agoff, Nicholas

    2010-01-01

    Areas of hypoattenuation in the liver which do not have mass effect are typically thought to represent focal fatty infiltration. Rarely, tumors can present without mass effect in the liver. We present a case in which areas of liver hypoattenuation which were initially thought to represent focal fatty infiltration on CT due to lack of mass effect had abnormal uptake on a FDG PET/CT exam; these areas were due to secondary hepatic involvement from non-Hodgkin’s lymphoma. PMID:22470725

  4. A new CT prostate segmentation for CT-based HDR brachytherapy

    NASA Astrophysics Data System (ADS)

    Yang, Xiaofeng; Rossi, Peter; Ogunleye, Tomi; Jani, Ashesh B.; Curran, Walter J.; Liu, Tian

    2014-03-01

    High-dose-rate (HDR) brachytherapy has become a popular treatment modality for localized prostate cancer. Prostate HDR treatment involves placing 10 to 20 catheters (needles) into the prostate gland, and then delivering radiation dose to the cancerous regions through these catheters. These catheters are often inserted with transrectal ultrasound (TRUS) guidance and the HDR treatment plan is based on the CT images. The main challenge for CT-based HDR planning is to accurately segment prostate volume in CT images due to the poor soft tissue contrast and additional artifacts introduced by the catheters. To overcome these limitations, we propose a novel approach to segment the prostate in CT images through TRUS-CT deformable registration based on the catheter locations. In this approach, the HDR catheters are reconstructed from the intra-operative TRUS and planning CT images, and then used as landmarks for the TRUS-CT image registration. The prostate contour generated from the TRUS images captured during the ultrasound-guided HDR procedure was used to segment the prostate on the CT images through deformable registration. We conducted two studies. A prostate-phantom study demonstrated a submillimeter accuracy of our method. A pilot study of 5 prostate-cancer patients was conducted to further test its clinical feasibility. All patients had 3 gold markers implanted in the prostate that were used to evaluate the registration accuracy, as well as previous diagnostic MR images that were used as the gold standard to assess the prostate segmentation. For the 5 patients, the mean gold-marker displacement was 1.2 mm; the prostate volume difference between our approach and the MRI was 7.2%, and the Dice volume overlap was over 91%. Our proposed method could improve prostate delineation, enable accurate dose planning and delivery, and potentially enhance prostate HDR treatment outcome.

  5. Spiral CT image deblurring for cochlear implantation.

    PubMed

    Wang, G; Vannier, M W; Skinner, M W; Cavalcanti, M G; Harding, G W

    1998-04-01

    Cochlear implantation is the standard treatment for profound hearing loss. Preimplantation and postimplantation spiral computed tomography (CT) is essential in several key clinical and research aspects. The maximum image resolution with commercial spiral CT scanners is insufficient to define clearly anatomical features and implant electrode positions in the inner ear. In this paper, we develop an expectation-maximization (EM)-like iterative deblurring algorithm to achieve spiral CT image super-resolution for cochlear implantation, assuming a spatially invariant linear spiral CT system with a three-dimensional (3-D) separable Gaussian point spread function (PSF). We experimentally validate the 3-D Gaussian blurring model via phantom measurement and profile fitting. The imaging process is further expressed as convolution of an isotropic 3-D Gaussian PSF and a blurred underlying volumetric image. Under practical conditions, an oblique reconstructed section is approximated as convolution of an isotropic two-dimensional (2-D) Gaussian PSF and the corresponding actual cross section. The spiral CT image deblurring algorithm is formulated with sieve and resolution kernels for suppressing noise and edge artifacts. A typical cochlear cross section is used for evaluation, demonstrating a resolution gain up to 30%40% according to the correlation criterion. Physical phantoms, preimplantation and postimplantation patients are reconstructed into volumes of 0.1-mm cubic voxels. The patient images are digitally unwrapped along the central axis of the cochlea and the implanted electrode array respectively, then oblique sections orthogonal to the central axis formed. After deblurring, representation of structural features is substantially improved in all the cases. PMID:9688157

  6. Imaging features of rhinosporidiosis on contrast CT

    PubMed Central

    Prabhu, Shailesh M; Irodi, Aparna; Khiangte, Hannah L; Rupa, V; Naina, P

    2013-01-01

    Context: Rhinosporidiosis is a chronic granulomatous disease endemic in certain regions of India. Computed tomography (CT) imaging appearances of rhinosporidiosis have not been previously described in the literature. Aims: To study imaging features in rhinosporidiosis with contrast-enhanced CT and elucidate its role in the evaluation of this disease. Materials and Methods: Sixteen patients with pathologically proven rhinosporidiosis were included in the study. Contrast-enhanced CT images were analyzed retrospectively and imaging findings were correlated with surgical and histopathologic findings. Results: A total of 29 lesions were found and evaluated. On contrast-enhanced CT, rhinosporidiosis was seen as moderately enhancing lobulated or irregular soft tissue mass lesions in the nasal cavity (n = 13), lesions arising in nasal cavity and extending through choana into nasopharynx (n = 5), pedunculated polypoidal lesions arising from the nasopharyngeal wall (n = 5), oropharyngeal wall (n = 2), larynx (n = 1), bronchus (n = 1), skin and subcutaneous tissue (n = 2). The inferior nasal cavity comprising nasal floor, inferior turbinate, and inferior meatus was the most common site of involvement (n = 13). Surrounding bone involvement was seen in the form of rarefaction (n = 6), partial (n = 3) or complete erosion (n = 3) of inferior turbinate, thinning of medial maxillary wall (n = 2), and septal erosion (n = 2). Nasolacrimal duct involvement was seen in four cases. Conclusions: Contrast-enhanced CT has an important role in delineating the site and extent of the disease, as well as the involvement of surrounding bone, nasolacrimal duct and tracheobronchial tree. This provides a useful roadmap prior to surgery. PMID:24347850

  7. Implications of CT noise and artifacts for quantitative {sup 99m}Tc SPECT/CT imaging

    SciTech Connect

    Hulme, K. W.; Kappadath, S. C.

    2014-04-15

    Purpose: This paper evaluates the effects of computed tomography (CT) image noise and artifacts on quantitative single-photon emission computed-tomography (SPECT) imaging, with the aim of establishing an appropriate range of CT acquisition parameters for low-dose protocols with respect to accurate SPECT attenuation correction (AC). Methods: SPECT images of two geometric and one anthropomorphic phantom were reconstructed iteratively using CT scans acquired at a range of dose levels (CTDI{sub vol} = 0.4 to 46 mGy). Resultant SPECT image quality was evaluated by comparing mean signal, background noise, and artifacts to SPECT images reconstructed using the highest dose CT for AC. Noise injection was performed on linear-attenuation (μ) maps to determine the CT noise threshold for accurate AC. Results: High levels of CT noise (σ ∼ 200–400 HU) resulted in low μ-maps noise (σ ∼ 1%–3%). Noise levels greater than ∼10% in 140 keV μ-maps were required to produce visibly perceptible increases of ∼15% in {sup 99m}Tc SPECT images. These noise levels would be achieved at low CT dose levels (CTDI{sub vol} = 4 μGy) that are over 2 orders of magnitude lower than the minimum dose for diagnostic CT scanners. CT noise could also lower (bias) the expected μ values. The relative error in reconstructed SPECT signal trended linearly with the relative shift in μ. SPECT signal was, on average, underestimated in regions corresponding with beam-hardening artifacts in CT images. Any process that has the potential to change the CT number of a region by ∼100 HU (e.g., misregistration between CT images and SPECT images due to motion, the presence of contrast in CT images) could introduce errors in μ{sub 140} {sub keV} on the order of 10%, that in turn, could introduce errors on the order of ∼10% into the reconstructed {sup 99m}Tc SPECT image. Conclusions: The impact of CT noise on SPECT noise was demonstrated to be negligible for clinically achievable CT parameters. Because

  8. Attenuation correction of PET cardiac data with low-dose average CT in PET/CT

    SciTech Connect

    Pan Tinsu; Mawlawi, Osama; Luo, Dershan; Liu, Hui H.; Chi Paichun, M.; Mar, Martha V.; Gladish, Gregory; Truong, Mylene; Erasmus, Jeremy Jr.; Liao Zhongxing; Macapinlac, H. A.

    2006-10-15

    We proposed a low-dose average computer tomography (ACT) for attenuation correction (AC) of the PET cardiac data in PET/CT. The ACT was obtained from a cine CT scan of over one breath cycle per couch position while the patient was free breathing. We applied this technique on four patients who underwent tumor imaging with {sup 18}F-FDG in PET/CT, whose PET data showed high uptake of {sup 18}F-FDG in the heart and whose CT and PET data had misregistration. All four patients did not have known myocardiac infarction or ischemia. The patients were injected with 555-740 MBq of {sup 18}F-FDG and scanned 1 h after injection. The helical CT (HCT) data were acquired in 16 s for the coverage of 100 cm. The PET acquisition was 3 min per bed of 15 cm. The duration of cine CT acquisition per 2 cm was 5.9 s. We used a fast gantry rotation cycle time of 0.5 s to minimize motion induced reconstruction artifacts in the cine CT images, which were averaged to become the ACT images for AC of the PET data. The radiation dose was about 5 mGy for 5.9 s cine duration. The selection of 5.9 s was based on our analysis of the respiratory signals of 600 patients; 87% of the patients had average breath cycles of less than 6 s and 90% had standard deviations of less than 1 s in the period of breath cycle. In all four patient studies, registrations between the CT and the PET data were improved. An increase of average uptake in the anterior and the lateral walls up to 48% and a decrease of average uptake in the septal and the inferior walls up to 16% with ACT were observed. We also compared ACT and conventional slow scan CT (SSCT) of 4 s duration in one patient study and found ACT was better than SSCT in depicting average respiratory motion and the SSCT images showed motion-induced reconstruction artifacts. In conclusion, low-dose ACT improved registration of the CT and the PET data in the heart region in our study of four patients. ACT was superior than SSCT for depicting average respiration

  9. Normal and pathologic CT anatomy of the mandible

    SciTech Connect

    Osborn, A.G.; Hanafee, W.H.; Mancuso, A.A.

    1982-09-01

    The value of computed tomography (CT) in the diagnosis and management of a wide variety of facial lesions has been amply demonstrated. While a number of studies have focused on CT anatomy of the paranasal sinuses, nose, and nasopharynx, none has concentrated on the mandible. Although the mandible is difficult to image because of its complex, curving surfaces and the presence of artifact-producing amalgam fillings or restorations, CT of the mandible can nevertheless be highly informative in selected cases. This pictorial essay depicts normal gross and CT anatomy of the mandible and presents a series of cases that illustrate the utility of CT in examining mandibular lesions.

  10. Evaluation of CT-based SUV normalization

    NASA Astrophysics Data System (ADS)

    Devriese, Joke; Beels, Laurence; Maes, Alex; Van de Wiele, Christophe; Pottel, Hans

    2016-09-01

    The purpose of this study was to determine patients’ lean body mass (LBM) and lean tissue (LT) mass using a computed tomography (CT)-based method, and to compare standardized uptake value (SUV) normalized by these parameters to conventionally normalized SUVs. Head-to-toe positron emission tomography (PET)/CT examinations were retrospectively retrieved and semi-automatically segmented into tissue types based on thresholding of CT Hounsfield units (HU). The following HU ranges were used for determination of CT-estimated LBM and LT (LBMCT and LTCT):  ‑180 to  ‑7 for adipose tissue (AT), ‑6 to 142 for LT, and 143 to 3010 for bone tissue (BT). Formula-estimated LBMs were calculated using formulas of James (1976 Research on Obesity: a Report of the DHSS/MRC Group (London: HMSO)) and Janmahasatian et al (2005 Clin. Pharmacokinet. 44 1051–65), and body surface area (BSA) was calculated using the DuBois formula (Dubois and Dubois 1989 Nutrition 5 303–11). The CT segmentation method was validated by comparing total patient body weight (BW) to CT-estimated BW (BWCT). LBMCT was compared to formula-based estimates (LBMJames and LBMJanma). SUVs in two healthy reference tissues, liver and mediastinum, were normalized for the aforementioned parameters and compared to each other in terms of variability and dependence on normalization factors and BW. Comparison of actual BW to BWCT shows a non-significant difference of 0.8 kg. LBMJames estimates are significantly higher than LBMJanma with differences of 4.7 kg for female and 1.0 kg for male patients. Formula-based LBM estimates do not significantly differ from LBMCT, neither for men nor for women. The coefficient of variation (CV) of SUV normalized for LBMJames (SUVLBM-James) (12.3%) was significantly reduced in liver compared to SUVBW (15.4%). All SUV variances in mediastinum were significantly reduced (CVs were 11.1–12.2%) compared to SUVBW (15.5%), except SUVBSA (15.2%). Only SUVBW and SUVLBM

  11. Evaluation of CT-based SUV normalization.

    PubMed

    Devriese, Joke; Beels, Laurence; Maes, Alex; Van de Wiele, Christophe; Pottel, Hans

    2016-09-01

    The purpose of this study was to determine patients' lean body mass (LBM) and lean tissue (LT) mass using a computed tomography (CT)-based method, and to compare standardized uptake value (SUV) normalized by these parameters to conventionally normalized SUVs. Head-to-toe positron emission tomography (PET)/CT examinations were retrospectively retrieved and semi-automatically segmented into tissue types based on thresholding of CT Hounsfield units (HU). The following HU ranges were used for determination of CT-estimated LBM and LT (LBMCT and LTCT):  -180 to  -7 for adipose tissue (AT), -6 to 142 for LT, and 143 to 3010 for bone tissue (BT). Formula-estimated LBMs were calculated using formulas of James (1976 Research on Obesity: a Report of the DHSS/MRC Group (London: HMSO)) and Janmahasatian et al (2005 Clin. Pharmacokinet. 44 1051-65), and body surface area (BSA) was calculated using the DuBois formula (Dubois and Dubois 1989 Nutrition 5 303-11). The CT segmentation method was validated by comparing total patient body weight (BW) to CT-estimated BW (BWCT). LBMCT was compared to formula-based estimates (LBMJames and LBMJanma). SUVs in two healthy reference tissues, liver and mediastinum, were normalized for the aforementioned parameters and compared to each other in terms of variability and dependence on normalization factors and BW. Comparison of actual BW to BWCT shows a non-significant difference of 0.8 kg. LBMJames estimates are significantly higher than LBMJanma with differences of 4.7 kg for female and 1.0 kg for male patients. Formula-based LBM estimates do not significantly differ from LBMCT, neither for men nor for women. The coefficient of variation (CV) of SUV normalized for LBMJames (SUVLBM-James) (12.3%) was significantly reduced in liver compared to SUVBW (15.4%). All SUV variances in mediastinum were significantly reduced (CVs were 11.1-12.2%) compared to SUVBW (15.5%), except SUVBSA (15.2%). Only SUVBW and SUVLBM-James show independence

  12. Patient doses from hybrid SPECT-CT procedures.

    PubMed

    Avramova-Cholakova, S; Dimcheva, M; Petrova, E; Garcheva, M; Dimitrova, M; Palashev, Y; Vassileva, J

    2015-07-01

    The aim of this work is to estimate patient doses from hybrid single-photon emission computed tomography (SPECT) and computed tomography (CT) procedures. The study involved all four SPECT-CT systems in Bulgaria. Effective dose was estimated for about 100 patients per system. Ten types of examinations were considered, representing all diagnostic procedures performed in the SPECT-CT systems. Effective doses from the SPECT component were calculated applying the ICRP 53 and ICRP 80 conversion coefficients. Computed tomography dose index and dose length product were retrospectively obtained from the archives of the systems, and effective doses from the CT component were calculated with CT-Expo software. Parallel estimation of CT component contribution with the National Radiological Protection Board (NRPB) conversion coefficients was performed where applicable. Large variations were found in the current practice of SPECT-CT imaging. Optimisation actions and diagnostic reference levels were proposed. PMID:25862537

  13. Issues in mapping LOINC laboratory tests to SNOMED CT.

    PubMed

    Bodenreider, Olivier

    2008-01-01

    Comprehensive clinical terminologies such as SNOMED CT tend to overlap with specialized terminologies such as LOINC (e.g., for the domain of laboratory procedures). Terminological systems such as the UMLS are often used to bridge between terminologies. However, the integration of LOINC in the UMLS and with other terminologies remains suboptimal. We mapped concepts for laboratory tests from LOINC to pre-coordinated SNOMED CT concepts, based on shared relations to other concepts. As LOINC is finer-grained than SNOMED CT, several LOINC codes tend to map to the same SNOMED CT concept. However, a large proportion of LOINC codes could not be mapped to SNOMED CT through this approach, because of underspecified definitions in SNOMED CT and a lack of fine-grained, pre-coordinated concepts in SNOMED CT. PMID:18999311

  14. Correlation of CT perfusion and CT volumetry in patients with Alzheimer’s disease

    PubMed Central

    Czarnecka, Anna; Zimny, Anna; Sąsiadek, Marek

    2010-01-01

    Summary Background: Both brain atrophy and decrease of perfusion are observed in dementive diseases. The aim of the study was to correlate the results of brain perfusion CT (pCT) and CT volumetry in patients with Alzheimer’s disease (AD). Material/Methods: Forty-eight patients with AD (mean age of 71.3 years) underwent brain pCT and CT volumetry. The pCT was performed at the level of basal ganglia after the injection of contrast medium (50 ml, 4 ml/sec.) with serial scanning (delay 7 sec, 50 scans, 1 scan/sec). Volumetric measurements were carried out on the basis of source images, with the use of a dedicated CT software combined with manual outlining of the regions of interest in extracerebral and intraventricular CSF spaces. Perfusion parameters of the cerebral blood flow (CBF) and cerebral blood volume (CBV) from the grey matter of frontal and temporal as well as basal ganglia were compared statistically with the volumetric measurements of frontal and temporal cortical atrophy as well as subcortical atrophy. Results: A statistically significant positive correlation was found between the values of CBF and CBV in the basal ganglia and the volumes of the lateral and third ventricles. The comparison of CBF and CBV results with the volumetric measurements in the areas of the frontal and temporal lobes showed mostly negative correlations, but none of them was of statistical significance. Conclusions: In patients with AD, the degree of cortical atrophy is not correlated with the decrease of perfusion in the grey matter and subcortical atrophy is not correlated with the decrease of perfusion in the basal ganglia region. It suggests that functional and structural changes in AD are not related to each other. PMID:22802771

  15. A realistic simulation framework for assessing deformable slice-to-volume (CT-fluoroscopy/CT) registration

    NASA Astrophysics Data System (ADS)

    Yaniv, Ziv; Stenzel, Roland; Cleary, Kevin; Banovac, Filip

    2006-03-01

    Lung cancer screening for early diagnosis is a clinically important problem. One screening method is to test tissue samples obtained from CT-fluoroscopy (CTF) guided lung biopsy. CTF provides real-time imaging; however on most machines the view is limited to a single slice. Mentally reconstructing the direction of the needle when it is not in the imaging plane is a difficult task. We are currently developing 3D visualization software that will augment the physician's ability to perform this task. At the beginning of the procedure a CT scan is acquired at breath-hold. The physician then specifies an entry point and a target point on the CT. As the procedure advances the physician acquires a CTF image at breath-hold; the system then registers the current setup to the CT scan. To assess the performance of different registration algorithms for CTF/CT registration we propose to use simulated CTF images. These images are created by deforming the original CT volume and extracting a slice from it. Realistic deformation of the CT volume is achieved by using positional information from electromagnetically tracked fiducials, acquired throughout the respiratory cycle. To estimate the dense displacement field underlying the sparse displacement field provided by the fiducials we use radial basis function interpolation. Finally, we evaluated Thirion's "demons" algorithm, as implemented in ITK, for the task of slice-to-volume registration. We found it to be unsuitable for this task, as in most cases the recovered displacements were less than 50% of the original ones.

  16. Intramyocardial capillary blood volume estimated by whole-body CT: validation by micro-CT

    NASA Astrophysics Data System (ADS)

    Dong, Yue; Beighley, Patricia E.; Eaker, Diane R.; Zamir, Mair; Ritman, Erik L.

    2008-03-01

    Fast CT has shown that myocardial perfusion (F) is related to myocardial intramuscular blood volume (Bv) as Bv=A*F+B*F 1/2 where A,B are constant coefficients. The goal of this study was to estimate the range of diameters of the vessels that are represented by the A*F term. Pigs were placed in an Electron Beam CT (EBCT) scanner for a perfusion CT scan sequence over 40 seconds after an IV contrast agent injection. Intramyocardial blood volume (Bv) and flow (F) were calculated in a region of the myocardium perfused by the LAD. Coefficients A and B were estimated over the range of F=1-5ml/g/min. After the CT scan, the LAD was injected with Microfil (R) contrast agent following which the myocardium was scanned by micro-CT at 20μm, 4μm and 2.5 μm cubic voxel resolutions. The Bv of the intramyocardial vessels was calculated for diameter ranges d=0-5, 5-10, 10-15, 15-20μm, etc. EBCT-derived data were presented so that it could be directly compared the micro-CT data. The results indicated that the blood in vessels less than 10μm in lumen diameter occupied 0.27-0.42 of total intravascular blood volume, which is in good agreement with EBCT-based values 0.28-0.48 (R2 =0.96). We conclude that whole-body CT image data obtained during the passage of a bolus of IV contrast agent can provide a measure of the intramyocardial intracapillary blood volume.

  17. Prior CT imaging history for patients who undergo PAN CT for acute traumatic injury

    PubMed Central

    Kenter, Jeremy; Blow, Osbert; Krall, Scott P.; Gest, Albert; Smith, Cynthia

    2015-01-01

    Objective. A single PAN scan may provide more radiation to a patient than is felt to be safe within a one-year period. Our objective was to determine how many patients admitted to the trauma service following a PAN scan had prior CT imaging within our six-hospital system. Methods. We performed a secondary analysis of a prospectively collected trauma registry. The study was based at a level-two trauma center and five affiliated hospitals, which comprise 70.6% of all Emergency Department visits within a twelve county region of southern Texas. Electronic medical records were reviewed dating from the point of trauma evaluation back to December 5, 2005 to determine evidence of prior CT imaging. Results. There were 867 patients were admitted to the trauma service between January 1, 2012 and December 31, 2012. 460 (53%) received a PAN scan and were included in the study group. The mean age of the study group was 37.7 ± 1.54 years old, 24.8% were female, and the mean ISS score was 13.4 ± 1.07. The most common mechanism of injury was motor vehicle collision (47%). 65 (14%; 95% CI [11–18]%) of the patients had at least one prior CT. The most common prior studies performed were: CT head (29%; 19–42%), CT Face (29%; 19–42%) and CT Abdomen and Pelvis (18%; 11–30%). Conclusion. Within our trauma registry, 14% of patients had prior CT imaging within our hospital system before their traumatic event and PAN scan. PMID:26056616

  18. A study evaluating the dependence of the patient dose on the CT dose change in a SPECT/CT scan

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Hyun; Kim, Ho-Sung; Dong, Kyung-Rae; Chung, Woon-Kwan; Cho, Jae-Hwan; Shin, Jae-Woo

    2012-07-01

    This study assessed ways of reducing the patient dose by examining the dependence of the patient dose on the CT (computed tomography) dose in a SPECT (single-photon emission computed tomography)/CT scan. To measure the patient dose, we used Precedence 16 SPECT/CT along with a phantom for the CT dose measurement (CT dose phantom kit for adult's head and body, Model 76-414-4150), a 100-mm ionization chamber (CT Ion Chamber) and an X-ray detector (Victoreen Model 4000M+). In addition, the patient dose was evaluated under conditions similar to those for an actual examination using an ImPACT (imaging performance assessment of CT scanners) dosimetry calculator in the Monte Carlo simulation method. The experimental method involved the use of a CT dose phantom to measure the patient dose under different CT conditions (kVp and mAs) to determine the CTDI (CT dose index) under each condition. An ImPACT dosimetry calculator was also used to measure CTDIw (CT dose index water ), CTDIv (CT dose index volume ), DLP (dose-length product), and effective dose. According to the patient dose measurements using the CT dose phantom, the CTDI showed an approximately 54 fold difference between when the maximum (140 kVp and 250 mAs) and the minimum dose (90 kVp and 25 mAs) was used. The CTDI showed a 4.2 fold difference between the conditions (120 kVp and 200 mAs) used mainly in a common CT scan and the conditions (120 kVp and 50 mAs) used mainly in a SPECT/CT scan. According to the measurement results using the dosimetry calculator, the effective dose showed an approximately 35 fold difference between the conditions for the maximum and the minimum doses, as in the case with the CT dose phantom. The effective dose showed a 4.1 fold difference between the conditions used mainly in a common CT scan and those used mainly in a SPECT/CT scan. This study examined the patient dose by reducing the CT dose in a SPECT/CT scan. As various examinations can be conducted due to the development of

  19. Body-wide anatomy recognition in PET/CT images

    NASA Astrophysics Data System (ADS)

    Wang, Huiqian; Udupa, Jayaram K.; Odhner, Dewey; Tong, Yubing; Zhao, Liming; Torigian, Drew A.

    2015-03-01

    With the rapid growth of positron emission tomography/computed tomography (PET/CT)-based medical applications, body-wide anatomy recognition on whole-body PET/CT images becomes crucial for quantifying body-wide disease burden. This, however, is a challenging problem and seldom studied due to unclear anatomy reference frame and low spatial resolution of PET images as well as low contrast and spatial resolution of the associated low-dose CT images. We previously developed an automatic anatomy recognition (AAR) system [15] whose applicability was demonstrated on diagnostic computed tomography (CT) and magnetic resonance (MR) images in different body regions on 35 objects. The aim of the present work is to investigate strategies for adapting the previous AAR system to low-dose CT and PET images toward automated body-wide disease quantification. Our adaptation of the previous AAR methodology to PET/CT images in this paper focuses on 16 objects in three body regions - thorax, abdomen, and pelvis - and consists of the following steps: collecting whole-body PET/CT images from existing patient image databases, delineating all objects in these images, modifying the previous hierarchical models built from diagnostic CT images to account for differences in appearance in low-dose CT and PET images, automatically locating objects in these images following object hierarchy, and evaluating performance. Our preliminary evaluations indicate that the performance of the AAR approach on low-dose CT images achieves object localization accuracy within about 2 voxels, which is comparable to the accuracies achieved on diagnostic contrast-enhanced CT images. Object recognition on low-dose CT images from PET/CT examinations without requiring diagnostic contrast-enhanced CT seems feasible.

  20. Pathological calcifications studied with micro-CT

    NASA Astrophysics Data System (ADS)

    Stock, Stuart R.; Rajamannan, Nalini M.; Brooks, Ellen R.; Langman, Craig B.; Pachman, Lauren M.

    2004-10-01

    The microstructure of pathological biomineral deposits has received relatively little attention, perhaps, in part because of the difficulty preparing samples for microscopy. MicroCT avoids these difficulties, and laboratory microCT results are reviewed for aortic valve calcification (human as well as a rabbit model), for human renal calculi (stones) and for calcinoses formed in juvenile dermatomyositis (JDM). In calcified aortic valves of rabbits, numerical analysis of the data shows statistically significant correlation with diet. In a large kidney stone the pattern of mineralization is clearly revealed and may provide a temporal blueprint for stone growth. In JDM calcified deposits, very different microstructures are observed and may be related to processes unique to this disease.

  1. CT Image Processing Using Public Digital Networks

    PubMed Central

    Rhodes, Michael L.; Azzawi, Yu-Ming; Quinn, John F.; Glenn, William V.; Rothman, Stephen L.G.

    1984-01-01

    Nationwide commercial computer communication is now commonplace for those applications where digital dialogues are generally short and widely distributed, and where bandwidth does not exceed that of dial-up telephone lines. Image processing using such networks is prohibitive because of the large volume of data inherent to digital pictures. With a blend of increasing bandwidth and distributed processing, network image processing becomes possible. This paper examines characteristics of a digital image processing service for a nationwide network of CT scanner installations. Issues of image transmission, data compression, distributed processing, software maintenance, and interfacility communication are also discussed. Included are results that show the volume and type of processing experienced by a network of over 50 CT scanners for the last 32 months.

  2. Applying Evolutionary Terminology Auditing to SNOMED CT

    PubMed Central

    Ceusters, Werner

    2010-01-01

    Evolutionary Terminology Auditing is a technique designed to measure quality improvements of terminologies over successive versions. It uses the most recent version of a terminology as a benchmark and assumes that changes in the underlying ontology correspond to changes in either that part of reality that is covered by the terminology, or the authors’ understanding – if not the ‘state of the art’ in general – thereof. Applied to SNOMED CT over 18 versions, it reveals that at the level of the concepts minimal improvements are obtained and that the second assumption holds for far less changes than one would expect. It is recommended that future versions of SNOMED CT provide more explicit documentation for each introduced change. PMID:21346948

  3. [Omental infarction: CT findings (case report)].

    PubMed

    Yildiz, Seçil; Atasoy, Cetin; Yağci, Cemil; Akyar, Serdar

    2004-06-01

    Omental infarction, the end result of impaired perfusion of the greater omentum, is an uncommon cause of acute abdominal pain. Because its clinical symptoms are nonspecific, it is usually confused with more common conditions such as appendicitis or cholecystitis. Consequently, the diagnosis is generally made intraoperatively. However, computed tomography shows characteristic findings and allows a reliable preoperative diagnosis, preventing unnecessary laparotomy. We report two cases of omental infarction, and describe typical CT findings of this rare entitiy. PMID:15236134

  4. Petrous apex mucocele: high resolution CT.

    PubMed

    Memis, A; Memis, A; Alper, H; Calli, C; Ozer, H; Ozdamar, N

    1994-11-01

    Mucocele of the petrous apex is very rare, only three cases having been reported. Since this area is inaccessible to direct examination, imaging, preferably high resolution computed tomography (HR CT) is essential. We report a case showing an eroding, non enhancing mass with sharp, lobulated contours, within the petrous apex. The presence of a large air cell on the opposite side suggested a mucocele. PMID:7862284

  5. Less common CT features of medulloblastoma

    SciTech Connect

    Zee, C.S; Segall, H.D.; Miller, C.; Ahmad, J.; McComb, J.G.; Han, J.S.; Park, S.H.

    1982-07-01

    While many medulloblastomas have characteristic features on computed tomography (CT), a significant number have atypical features, including a cystic or necrotic component, calcification, hemorrhage, lack of contrast enhancement, and eccentric location, and/or direct supratentorial extension. Of 30 consecutive untreated cases reviewed by the authors, 14 (47%) had such findings. Failure to make the proper diagnosis will result in some cases if these features are not recognized as possible signs of medulloblastoma.

  6. Resolution-enhancing hybrid, spectral CT reconstruction

    NASA Astrophysics Data System (ADS)

    Clark, D. P.; Badea, C. T.

    2016-04-01

    Spectral x-ray imaging based on photon-counting x-ray detectors (PCXD) is an area of growing interest. By measuring the energy of x-ray photons, a spectral CT system can better differentiate elements using a single scan. However, the spatial resolution achievable with most PCXDs limits their application, particularly in preclinical CT imaging. Consequently, our group is developing a hybrid micro-CT scanner based on a high-resolution, energy-integrating (EID) detector and a lower-resolution, PCXD. To complement this system, we propose and demonstrate a hybrid, spectral CT reconstruction algorithm which robustly combines the spectral contrast of the PCXD with the spatial resolution of the EID. Specifically, the high-resolution, spectrally resolved data (X) is recovered as the sum of two matrices: one with low column rank (XL) determined from the EID data and one with intensity gradient sparse columns (XS) corresponding to the upsampled spectral contrast obtained from the PCXD data. We test the proposed algorithm in a feasibility study focused on molecular imaging of atherosclerotic plaque using activatable iodine and gold nanoparticles. The results show accurate estimation of material concentrations at increased spatial resolution for a voxel size ratio between the PCXD and the EID of 500 μm3:100 μm3. Specifically, regularized, iterative reconstruction of the MOBY mouse phantom around the K-edges of iodine (33.2 keV) and gold (80.7 keV) reduces the reconstruction error by more than a factor of three relative to least-squares, algebraic reconstruction. Likewise, the material decomposition accuracy into iodine, gold, calcium, and water improves by more than a factor of two.

  7. Importance of extracolonic findings at IV contrast medium-enhanced CT colonography versus those at non-enhanced CT colonography.

    PubMed

    Spreng, Adrian; Netzer, Peter; Mattich, Joerg; Dinkel, Hans-Peter; Vock, Peter; Hoppe, Hanno

    2005-10-01

    To compare the clinical importance of extracolonic findings at intravenous (IV) contrast-enhanced CT colonography versus those at non-enhanced CT colonography. IV contrast medium-enhanced (n=72) and non-enhanced (n=30) multidetector CT colonography was performed in 102 symptomatic patients followed by conventional colonoscopy on the same day. The impact of extracolonic findings on further work up and treatment was assessed by a review of patient records. Extracolonic findings were divided into two groups: either leading to further work up respectively having an impact on therapy or not. A total of 303 extracolonic findings were detected. Of those, 71% (215/303) were found on IV contrast-enhanced CT, and 29% (88/303) were found on non-enhanced CT colonography. The extracolonic findings in 25% (26/102) of all patients led to further work up or had an impact on therapy. Twenty-two of these patients underwent CT colonography with IV contrast enhancement, and four without. The percentage of extracolonic findings leading to further work up or having an impact on therapy was higher for IV contrast-enhanced (31%; 22/72) than for non-enhanced (13%; 4/30) CT scans (P=0.12). IV contrast-enhanced CT colonography produced more extracolonic findings than non-enhanced CT colonography. A substantially greater proportion of findings on IV contrast-enhanced CT colonography led to further work up and treatment than did non-enhanced CT colonography. PMID:15965661

  8. Automated size-specific CT dose monitoring program: Assessing variability in CT dose

    SciTech Connect

    Christianson, Olav; Li Xiang; Frush, Donald; Samei, Ehsan

    2012-11-15

    Purpose: The potential health risks associated with low levels of ionizing radiation have created a movement in the radiology community to optimize computed tomography (CT) imaging protocols to use the lowest radiation dose possible without compromising the diagnostic usefulness of the images. Despite efforts to use appropriate and consistent radiation doses, studies suggest that a great deal of variability in radiation dose exists both within and between institutions for CT imaging. In this context, the authors have developed an automated size-specific radiation dose monitoring program for CT and used this program to assess variability in size-adjusted effective dose from CT imaging. Methods: The authors radiation dose monitoring program operates on an independent health insurance portability and accountability act compliant dosimetry server. Digital imaging and communication in medicine routing software is used to isolate dose report screen captures and scout images for all incoming CT studies. Effective dose conversion factors (k-factors) are determined based on the protocol and optical character recognition is used to extract the CT dose index and dose-length product. The patient's thickness is obtained by applying an adaptive thresholding algorithm to the scout images and is used to calculate the size-adjusted effective dose (ED{sub adj}). The radiation dose monitoring program was used to collect data on 6351 CT studies from three scanner models (GE Lightspeed Pro 16, GE Lightspeed VCT, and GE Definition CT750 HD) and two institutions over a one-month period and to analyze the variability in ED{sub adj} between scanner models and across institutions. Results: No significant difference was found between computer measurements of patient thickness and observer measurements (p= 0.17), and the average difference between the two methods was less than 4%. Applying the size correction resulted in ED{sub adj} that differed by up to 44% from effective dose estimates

  9. MR and CT arthrography of the wrist.

    PubMed

    Cerezal, Luis; de Dios Berná-Mestre, Juan; Canga, Ana; Llopis, Eva; Rolon, Alejandro; Martín-Oliva, Xavier; del Piñal, Francisco

    2012-02-01

    The study of the wrist represents a major diagnostic challenge because of its complex anatomy and the small size of individual structures. Recent advances in imaging techniques have increased our diagnostic capabilities. However, 3T magnets, multichannel specific wrist coils, and new MRI sequences have not restricted the indications of arthrographic imaging techniques (CT arthrography and MR arthrography). Distension of the different wrist compartments at CT arthrography and MR arthrography significantly improves the diagnostic accuracy for triangular fibrocartilage (TFC) complex injuries and carpal instability. Dedicated multichannel wrist coils are essential for an adequate study of the wrist, but the placement of these coils and the positioning of the wrist are also important for proper diagnosis. The development of dynamic multislice CT studies allows a diagnostic approach that combines dynamic information and the accurate assessment of ligaments and the TFC complex. New advances in arthroscopy have changed the anatomical description of the TFC with a functional division in the proximal and distal TFC complex, and they have allowed a better characterization of lesions of the TFC complex with subclassification of Palmer 1B and 1D lesions and description of new lesions not included in the Palmer classification, such as capsular injuries. PMID:22447235

  10. CT features of nonfunctioning islet cell carcinoma

    SciTech Connect

    Eelkema, E.A.; Stephens, D.H.; Ward, E.M.; Sheedy, P.F. II

    1984-11-01

    To determine the computed tomographic (CT) characteristics of nonfunctioning islet cell carcinoma of the pancreas, the CT scans of 27 patients with that disease were reviewed. The pancreatic tumor was identified as a mass in 26 patients (96%) Of the 25 tumors evaluated with contrast enhancement, 20 became partially diffusely hyperdense relative to nearby normal pancreatic tissue. Hepatic metastases were identified in 15 patients (56%), regional lymphadenopathy in 10 (37%), atrophy of the gland proximal to the tumor in six (22%), dilatation of the biliary ducts in five (19%), and dilatation of the pancreatic duct in four (15%). The CT appearances of the nonfunctioning islet cell tumors were compared with those of 100 ordinary (ductal) pancreatic adenocarcinomas. Although the two types of tumors were sometimes indistinguishable, features found to be more characteristic of islet cell carcinoma included a pancreatic mass of unusually large size, calcification within the tumor, and contrast enhancement of either the primary tumor or hepatic metastases. Involvement of the celiac axis or proximal superior mesenteric artery was limited to ductal carcinoma.

  11. Automatic Synthesis of Anthropomorphic Pulmonary CT Phantoms

    PubMed Central

    Jimenez-Carretero, Daniel; San Jose Estepar, Raul; Diaz Cacio, Mario; Ledesma-Carbayo, Maria J.

    2016-01-01

    The great density and structural complexity of pulmonary vessels and airways impose limitations on the generation of accurate reference standards, which are critical in training and in the validation of image processing methods for features such as pulmonary vessel segmentation or artery–vein (AV) separations. The design of synthetic computed tomography (CT) images of the lung could overcome these difficulties by providing a database of pseudorealistic cases in a constrained and controlled scenario where each part of the image is differentiated unequivocally. This work demonstrates a complete framework to generate computational anthropomorphic CT phantoms of the human lung automatically. Starting from biological and image-based knowledge about the topology and relationships between structures, the system is able to generate synthetic pulmonary arteries, veins, and airways using iterative growth methods that can be merged into a final simulated lung with realistic features. A dataset of 24 labeled anthropomorphic pulmonary CT phantoms were synthesized with the proposed system. Visual examination and quantitative measurements of intensity distributions, dispersion of structures and relationships between pulmonary air and blood flow systems show good correspondence between real and synthetic lungs (p > 0.05 with low Cohen’s d effect size and AUC values), supporting the potentiality of the tool and the usefulness of the generated phantoms in the biomedical image processing field. PMID:26731653

  12. CT Findings in Temporal Bone Osteoradionecrosis

    PubMed Central

    Ahmed, Salmaan; Gupta, Nakul; Hamilton, Jackson D.; Garden, Adam S.; Gidley, Paul W.; Ginsberg, Lawrence E.

    2014-01-01

    Purpose The goal of this study is to describe CT findings in patients with clinically proven temporal bone osteoradionecrosis (TB-ORN). Methods and materials CT scans of twenty patients were retrospectively evaluated for bony and soft tissue abnormalities. Clinical severity was graded based on level of therapy administered: mild (observation), moderate (antibiotics/hyperbaric oxygen), or severe (surgery). Results Radiation dose to the primary tumor ranged from 30 to 75.6 Gy. Time to onset of ORN from completion of radiation therapy was 2 to 22 years (median=7yrs). Clinical findings: Exposed bone=20/20, otorrhea=17/20, hearing loss=11/20, otalgia=10/20, facial nerve paralysis=2/20, gait imbalance=2/20. CT findings: EAC erosions=18/20, mastoid effusion=18/20, mastoid bony coalescence=5/20, enhancing soft tissue=6/20, soft tissue gas=6/20, temporomandibular joint/condylar erosion=3/20. 3 patients developed an abscess. Conclusion Mastoid effusion and EAC erosions are commonly seen with TB-ORN. Clinically moderate or severe cases of TB-ORN are more likely to demonstrate enhancing soft tissue (p=0.002), soft tissue gas (p=0.002), and temporomandibular joint involvement (p=0.07). PMID:24834883

  13. Comprehensive plaque assessment by coronary CT angiography.

    PubMed

    Maurovich-Horvat, Pál; Ferencik, Maros; Voros, Szilard; Merkely, Béla; Hoffmann, Udo

    2014-07-01

    Most acute coronary syndromes are caused by sudden luminal thrombosis due to atherosclerotic plaque rupture or erosion. Preventing such an event seems to be the only effective strategy to reduce mortality and morbidity of coronary heart disease. Coronary lesions prone to rupture have a distinct morphology compared with stable plaques, and provide a unique opportunity for noninvasive imaging to identify vulnerable plaques before they lead to clinical events. The submillimeter spatial resolution and excellent image quality of modern computed tomography (CT) scanners allow coronary atherosclerotic lesions to be detected, characterized, and quantified. Large plaque volume, low CT attenuation, napkin-ring sign, positive remodelling, and spotty calcification are all associated with a high risk of acute cardiovascular events in patients. Computation fluid dynamics allow the calculation of lesion-specific endothelial shear stress and fractional flow reserve, which add functional information to plaque assessment using CT. The combination of morphologic and functional characteristics of coronary plaques might enable noninvasive detection of vulnerable plaques in the future. PMID:24755916

  14. The Rh = ct universe and quintessence

    NASA Astrophysics Data System (ADS)

    Sultana, J.

    2016-03-01

    Over the last few years the Rh = ct universe has received a lot of attention, particularly when observational evidence seems to favour this over the standard Λ cold dark matter (ΛCDM) universe. Like the ΛCDM, the Rh = ct universe is based on a Friedmann-Robertson-Walker (FRW) cosmology where the total energy density ρ and pressure p of the cosmic fluid contain a dark energy component besides the usual (dark and baryonic) matter and radiation components. However, unlike the ΛCDM this model has the simple equation of state ρ + 3p = 0, i.e. its total active gravitational mass vanishes, which would therefore exclude a cosmological constant as the source of its dark energy component. Faced with this issue, in this paper, we examine various possible sources for the dark energy component of the Rh = ct universe and show that quintessence which has been used in other various dynamical dark energy models could also be a possible source in this case.

  15. Fabrication and control of CT number through polymeric composites based on coronary plaque CT phantom applications.

    PubMed

    Hoy, Carlton F O; Naguib, Hani E; Paul, Narinder

    2016-01-01

    Biomedical phantoms are commonly used for various medical imaging modalities to improve imaging quality and procedures. Current biomedical phantoms fabricated commercially are high in cost and limited in the specificity of human environments and structures that can be mimicked. This study aimed to control the measurable computed tomography (CT) number in Hounsfield units through polymeric biomedical phantom materials using controlled amounts of hydroxyapatite (hA). The purpose was to fabricate CT phantoms capable of mimicking various coronary plaque types while introducing a fabrication technique and basis for a numerical model to which the technique may be applied. The CT number is tunable based on the controlled material properties of electron density and atomic numbers. Three different polymeric matrices of polyethylene (PE), thermoplastic polyurethane (TPU), and polyvinylidene fluoride (PVDF) were selected due to their varied specific densities and ease of fabrication acting as integral properties for CT phantom fabrication. These polymers were processed together with additions of hA in mass percentages of 2.5, 5, 10, and 20% hA as well as a 0% hA as a control for each polymeric material. By adding hA to PE, TPU, and PVDF an increasing trend was exhibited between CT number and weight percent of hA. PMID:26958580

  16. CT volumetry of the skeletal tissues

    SciTech Connect

    Brindle, James M.; Alexandre Trindade, A.; Pichardo, Jose C.; Myers, Scott L.; Shah, Amish P.; Bolch, Wesley E.

    2006-10-15

    Computed tomography (CT) is an important and widely used modality in the diagnosis and treatment of various cancers. In the field of molecular radiotherapy, the use of spongiosa volume (combined tissues of the bone marrow and bone trabeculae) has been suggested as a means to improve the patient-specificity of bone marrow dose estimates. The noninvasive estimation of an organ volume comes with some degree of error or variation from the true organ volume. The present study explores the ability to obtain estimates of spongiosa volume or its surrogate via manual image segmentation. The variation among different segmentation raters was explored and found not to be statistically significant (p value >0.05). Accuracy was assessed by having several raters manually segment a polyvinyl chloride (PVC) pipe with known volumes. Segmentation of the outer region of the PVC pipe resulted in mean percent errors as great as 15% while segmentation of the pipe's inner region resulted in mean percent errors within {approx}5%. Differences between volumes estimated with the high-resolution CT data set (typical of ex vivo skeletal scans) and the low-resolution CT data set (typical of in vivo skeletal scans) were also explored using both patient CT images and a PVC pipe phantom. While a statistically significant difference (p value <0.002) between the high-resolution and low-resolution data sets was observed with excised femoral heads obtained following total hip arthroplasty, the mean difference between high-resolution and low-resolution data sets was found to be only 1.24 and 2.18 cm{sup 3} for spongiosa and cortical bone, respectively. With respect to differences observed with the PVC pipe, the variation between the high-resolution and low-resolution mean percent errors was a high as {approx}20% for the outer region volume estimates and only as high as {approx}6% for the inner region volume estimates. The findings from this study suggest that manual segmentation is a reasonably accurate

  17. An Open Library of CT Patient Projection Data

    PubMed Central

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

    2016-01-01

    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. PMID:27239087

  18. 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.

  19. Patient acceptance for CT colonography: what is the real issue?

    PubMed

    Thomeer, M; Bielen, D; Vanbeckevoort, D; Dymarkowski, S; Gevers, A; Rutgeerts, P; Hiele, M; Van Cutsem, E; Marchal, G

    2002-06-01

    The aim of this study was to evaluate the discomfort associated with CT colonography compared with colonoscopy and bowel purgation cleansing, and to evaluate patient preference between CT colonography and colonoscopy. In a total of 124 patients, scheduled for multidetector virtual CT colonography and diagnostic colonoscopy, patient acceptance and future preference were assessed during the different steps of the procedure (colon preparation, CT examination, and conventional colonoscopy). Patients who described contradictory findings between the degree of discomfort and their preference regarding follow-up examinations were retrospectively reinterviewed regarding the reason for this discrepancy. Colonoscopy was graded slightly more uncomfortable than virtual CT colonography, but the preparation was clearly the most uncomfortable part of the procedure. Concerning their preference regarding follow-up examinations, 71% of the patients preferred virtual CT colonography, 24% preferred colonoscopy, and 5% had no preference. Twenty-eight percent of the patients preferred virtual CT colonography despite that they thought it was equally or even more uncomfortable than colonoscopy. This was mainly due to the faster procedure (17 patients), the lower physical challenge (14 patients), and the lack of sedation (12 patients) of virtual CT colonography. Factors other than the discomfort related to the examinations play an important role in the patient's preference for virtual CT colonography, namely the faster procedure, the lower physical challenge, and the lack of sedation. Since the preparation plays a major decisive factor in the patient acceptance of virtual CT colonography, more attention should be given to fecal tagging. PMID:12042947

  20. An approach for quantitative image quality analysis for CT

    NASA Astrophysics Data System (ADS)

    Rahimi, Amir; Cochran, Joe; Mooney, Doug; Regensburger, Joe

    2016-03-01

    An objective and standardized approach to assess image quality of Compute Tomography (CT) systems is required in a wide variety of imaging processes to identify CT systems appropriate for a given application. We present an overview of the framework we have developed to help standardize and to objectively assess CT image quality for different models of CT scanners used for security applications. Within this framework, we have developed methods to quantitatively measure metrics that should correlate with feature identification, detection accuracy and precision, and image registration capabilities of CT machines and to identify strengths and weaknesses in different CT imaging technologies in transportation security. To that end we have designed, developed and constructed phantoms that allow for systematic and repeatable measurements of roughly 88 image quality metrics, representing modulation transfer function, noise equivalent quanta, noise power spectra, slice sensitivity profiles, streak artifacts, CT number uniformity, CT number consistency, object length accuracy, CT number path length consistency, and object registration. Furthermore, we have developed a sophisticated MATLAB based image analysis tool kit to analyze CT generated images of phantoms and report these metrics in a format that is standardized across the considered models of CT scanners, allowing for comparative image quality analysis within a CT model or between different CT models. In addition, we have developed a modified sparse principal component analysis (SPCA) method to generate a modified set of PCA components as compared to the standard principal component analysis (PCA) with sparse loadings in conjunction with Hotelling T2 statistical analysis method to compare, qualify, and detect faults in the tested systems.

  1. CT-SPECT fusion to correlate radiolabeled monoclonal antibody uptake with abdominal CT findings

    SciTech Connect

    Kramer, E.L.; Noz, M.E.; Sanger, J.J.; Megibow, A.J.; Maguire, G.Q. )

    1989-09-01

    To enhance the information provided by computed tomography (CT) and single photon emission computed tomography (SPECT) performed with radiolabeled, anti-carcinoembryonic antigen monoclonal antibody (MoAb), the authors performed fusion of these types of images from eight subjects with suspected colorectal adenocarcinoma. Section thickness and pixel size of the two studies were matched, coordinates of corresponding points from each study were identified, and CT sections were translated, rotated, and reprojected to match the corresponding SPECT scans. The CT-SPECT fusion enabled identification of anatomic sites of tumor-specific MoAb accumulation in four cases, showed non-specific MoAb accumulation in two, and helped confirm information only suggested by the two studies separately in one.

  2. Complications in CT-guided Procedures: Do We Really Need Postinterventional CT Control Scans?

    SciTech Connect

    Nattenmüller, Johanna Filsinger, Matthias Bryant, Mark Stiller, Wolfram Radeleff, Boris Grenacher, Lars Kauczor, Hans-Ullrich Hosch, Waldemar

    2013-06-19

    PurposeThe aim of this study is twofold: to determine the complication rate in computed tomography (CT)-guided biopsies and drainages, and to evaluate the value of postinterventional CT control scans.MethodsRetrospective analysis of 1,067 CT-guided diagnostic biopsies (n = 476) and therapeutic drainages (n = 591) in thoracic (n = 37), abdominal (n = 866), and musculoskeletal (ms) (n = 164) locations. Severity of any complication was categorized as minor or major. To assess the need for postinterventional CT control scans, it was determined whether complications were detected clinically, on peri-procedural scans or on postinterventional scans only.ResultsThe complication rate was 2.5 % in all procedures (n = 27), 4.4 % in diagnostic punctures, and 1.0 % in drainages; 13.5 % in thoracic, 2.0 % in abdominal, and 3.0 % in musculoskeletal procedures. There was only 1 major complication (0.1 %). Pneumothorax (n = 14) was most frequent, followed by bleeding (n = 9), paresthesia (n = 2), material damage (n = 1), and bone fissure (n = 1). Postinterventional control acquisitions were performed in 65.7 % (701 of 1,067). Six complications were solely detectable in postinterventional control acquisitions (3 retroperitoneal bleeds, 3 pneumothoraces); all other complications were clinically detectable (n = 4) and/or visible in peri-interventional controls (n = 21).ConclusionComplications in CT-guided interventions are rare. Of these, thoracic interventions had the highest rate, while pneumothoraces and bleeding were most frequent. Most complications can be detected clinically or peri-interventionally. To reduce the radiation dose, postinterventional CT controls should not be performed routinely and should be restricted to complicated or retroperitoneal interventions only.

  3. Deformable planning CT to cone-beam CT image registration in head-and-neck cancer

    SciTech Connect

    Hou Jidong; Guerrero, Mariana; Chen, Wenjuan; D'Souza, Warren D.

    2011-04-15

    Purpose: The purpose of this work was to implement and validate a deformable CT to cone-beam computed tomography (CBCT) image registration method in head-and-neck cancer to eventually facilitate automatic target delineation on CBCT. Methods: Twelve head-and-neck cancer patients underwent a planning CT and weekly CBCT during the 5-7 week treatment period. The 12 planning CT images (moving images) of these patients were registered to their weekly CBCT images (fixed images) via the symmetric force Demons algorithm and using a multiresolution scheme. Histogram matching was used to compensate for the intensity difference between the two types of images. Using nine known anatomic points as registration targets, the accuracy of the registration was evaluated using the target registration error (TRE). In addition, region-of-interest (ROI) contours drawn on the planning CT were morphed to the CBCT images and the volume overlap index (VOI) between registered contours and manually delineated contours was evaluated. Results: The mean TRE value of the nine target points was less than 3.0 mm, the slice thickness of the planning CT. Of the 369 target points evaluated for registration accuracy, the average TRE value was 2.6{+-}0.6 mm. The mean TRE for bony tissue targets was 2.4{+-}0.2 mm, while the mean TRE for soft tissue targets was 2.8{+-}0.2 mm. The average VOI between the registered and manually delineated ROI contours was 76.2{+-}4.6%, which is consistent with that reported in previous studies. Conclusions: The authors have implemented and validated a deformable image registration method to register planning CT images to weekly CBCT images in head-and-neck cancer cases. The accuracy of the TRE values suggests that they can be used as a promising tool for automatic target delineation on CBCT.

  4. Optical crosstalk in CT detectors and its effects on CT images

    NASA Astrophysics Data System (ADS)

    Youn, Hanbean; Kam, Soohwa; Han, Jong Chul; Kim, Ho Kyung

    2014-03-01

    Detectors for computed tomography (CT) typically consist of scintillator and photodiode arrays which are coupled using optical glue. Therefore, the leakage of optical photons generated in a scintillator block to neighboring pixel photodiodes through the optical glue layer is inevitable. Passivation layers to protect the silicon photodiode as well as the silicon layer itself, which is inactive to the optical photons, are another causes for the leakage. This optical crosstalk reduces image sharpness, and eventually will blur CT images. We have quantitatively investigated the optical crosstalk in CT detectors using the Monte Carlo technique. We performed the optical Monte Carlo simulations for various thicknesses of optical components in a 129 × 129 CT detector array. We obtained the coordinates of optical photons hitting the user-defined detection plane. From the coordinate information, we calculated the collection efficiency at the detection plane and the collection efficiency at the single pixel located just below the scintillator in which the optical photons were generated. Difference between the two quantities provided the optical crosstalk. In addition, using the coordinate information, we calculated point-spread functions as well as modulation-transfer functions from which we estimated the effective aperture due to the optical photon spreading. The optical crosstalk was most severely affected by the thickness of photodiode passivation layer. The effective aperture due to the optical crosstalk was about 110% of the detector pixel aperture for a 0.1 mm-thick passivation layer, and this signal blur was appeared as a relative error of about 3-4% in mismatches between CT images with and without the optical crosstalk. The detailed simulation results are shown and will be very useful for the design of CT detectors.

  5. Key components for artifact-free micro-CT and nano-CT instruments

    NASA Astrophysics Data System (ADS)

    Sasov, Alexander; Pauwels, Bart; Liu, Xuan; Bruyndonckx, Peter

    2010-09-01

    Proper selection of modern key components allows eliminating most artifacts in micro-CT and nano-CT systems already during data acquisition. X-ray cameras with direct photon detection allow avoiding ring artifacts. Newly developed fully depleted CCD sensors show an energy response similar to traditional cameras with a thin scintillator, but without any geometrical distortions and flashes from x-ray photons penetrating through the fiber optics. Air-bearing rotation stages and piezo-positioning minimizes mechanical inaccuracies in acquiring angular projections. Beam hardening can be eliminated by energy-selective photon counting imaging.

  6. Renal infarction: CT diagnosis and correlation between CT findings and etiologies

    SciTech Connect

    Wong, W.S.; Moss, A.A.; Federle, M.P.; Cochran, S.T.; London, S.S.

    1984-01-01

    The CT scans and the clinical records of 12 patients who had renal infarction were reviewed. The renal infarcts were classified as either focal or global. The CT findings were correlated with the etiologies of renal infarction. Embolism was the most common cause of renal infarcts that were multifocal with involvement of both kidneys. Trauma caused a unilateral global type of infract. A case of sickle cell anemia presented with multiple ''slit-like'' focal infarcts and enlarged kidneys. Forty-seven per cent of infarcts demonstrated the cortical rim sign, 11% were acapsular fluid collection, and 6% had an abnormally thickened renal fascia.

  7. Demons deformable registration of CT and cone-beam CT using an iterative intensity matching approach

    SciTech Connect

    Nithiananthan, Sajendra; Schafer, Sebastian; Uneri, Ali; and others

    2011-04-15

    Purpose: A method of intensity-based deformable registration of CT and cone-beam CT (CBCT) images is described, in which intensity correction occurs simultaneously within the iterative registration process. The method preserves the speed and simplicity of the popular Demons algorithm while providing robustness and accuracy in the presence of large mismatch between CT and CBCT voxel values (''intensity''). Methods: A variant of the Demons algorithm was developed in which an estimate of the relationship between CT and CBCT intensity values for specific materials in the image is computed at each iteration based on the set of currently overlapping voxels. This tissue-specific intensity correction is then used to estimate the registration output for that iteration and the process is repeated. The robustness of the method was tested in CBCT images of a cadaveric head exhibiting a broad range of simulated intensity variations associated with x-ray scatter, object truncation, and/or errors in the reconstruction algorithm. The accuracy of CT-CBCT registration was also measured in six real cases, exhibiting deformations ranging from simple to complex during surgery or radiotherapy guided by a CBCT-capable C-arm or linear accelerator, respectively. Results: The iterative intensity matching approach was robust against all levels of intensity variation examined, including spatially varying errors in voxel value of a factor of 2 or more, as can be encountered in cases of high x-ray scatter. Registration accuracy without intensity matching degraded severely with increasing magnitude of intensity error and introduced image distortion. A single histogram match performed prior to registration alleviated some of these effects but was also prone to image distortion and was quantifiably less robust and accurate than the iterative approach. Within the six case registration accuracy study, iterative intensity matching Demons reduced mean TRE to (2.5{+-}2.8) mm compared to (3.5{+-}3.0) mm

  8. Dual-energy CT revisited with multidetector CT: review of principles and clinical applications.

    PubMed

    Karçaaltıncaba, Muşturay; Aktaş, Aykut

    2011-09-01

    Although dual-energy CT (DECT) was first conceived in the 1970s, it was not widely used for CT indications. Recently, the simultaneous acquisition of volumetric dual-energy data has been introduced using multidetector CT (MDCT) with two X-ray tubes and rapid kVp switching (gemstone spectral imaging). Two major advantages of DECT are material decomposition by acquiring two image series with different kVp and the elimination of misregistration artifacts. Hounsfield unit measurements by DECT are not absolute and can change depending on the kVp used for an acquisition. Typically, a combination of 80/140 kVp is used for DECT, but for some applications, 100/140 kVp is preferred. In this study, we summarized the clinical applications of DECT and included images that were acquired using the dual-source CT and rapid kVp switching. In general, unenhanced images can be avoided by using DECT for body and neurological applications; iodine can be removed from the image, and a virtual, non-contrast (water) image can be obtained. Neuroradiological applications allow for the removal of bone and calcium from the carotid and brain CT angiography. Thorax applications include perfusion imaging in patients with pulmonary thromboemboli and other chest diseases, xenon ventilation-perfusion imaging and solitary nodule characterization. Cardiac applications include dual-energy cardiac perfusion, viability and cardiac iron detection. The removal of calcific plaques from arteries, bone removal and aortic stent graft evaluation may be achieved in the vascular system. Abdominal applications include the detection and characterization of liver and pancreas masses, the diagnosis of steatosis and iron overload, DECT colonoscopy and CT cholangiography. Urinary system applications are urinary calculi characterization (uric acid vs. non-uric acid), renal cyst characterization and mass characterization. Musculoskeletal applications permit the differentiation of gout from pseudogout and a reduction of

  9. Intra-abdominal desmoplastic small round cell tumors: CT and FDG-PET/CT findings with histopathological association

    PubMed Central

    CHEN, JINGJING; WU, ZENGJIE; SUN, BINBIN; LI, DACHENG; WANG, ZHENGUANG; LIU, FANGJUN; HUA, HUI

    2016-01-01

    Desmoplastic small round cell tumors (DSRCTs) are rare and aggressive malignant tumors. The aim of the present study was to analyze computed tomography (CT) and fluorodeoxyglucose positron emission tomography (FDG-PET)/CT imaging features of intra-abdominal desmoplastic DSRCT, and investigate the association of these features with histopathological results. The present study was a retrospective investigation of 4 patients with DSRCT. All patients underwent CT and dynamic CT, and 1 additionally underwent FDG-PET/CT scanning. Following a tumor resection, routine hematoxylin and eosin staining, and immunostaining, were performed and evaluated. Multiple large abdominopelvic masses were identified in all 4 patients; however, no indications of their site of origin were demonstrated. CT revealed soft-tissue masses with patchy foci of hypodense lesions. Contrast-enhanced CT revealed slightly or moderately heterogeneous enhancement of the lesions. Other observations from these patients included calcification (n=2), peritoneal seeding (n=3), hepatic metastasis (n=3), retroperitoneal lymphadenopathy (n=3) and ascites (n=2). FDG-PET/CT revealed multiple nodular increased FDG uptake in the abdominopelvic masses, and in the liver and peritoneum in 1 case. Intra-abdominal DSRCT demonstrated significant diagnostic characteristics on plain and contrast-enhanced CT. Multiple, bulky soft-tissue masses inside the peritoneal cavity, particularly in male adolescents and young adults, should be considered as potential cases of DSRCT. FDG-PET/CT techniques may be utilized to aid the staging of tumors. PMID:27123106

  10. Implementation of interior micro-CT on a carbon nanotube dynamic micro-CT scanner for lower radiation dose

    NASA Astrophysics Data System (ADS)

    Gong, Hao; Lu, Jianping; Zhou, Otto; Cao, Guohua

    2015-03-01

    Micro-CT is a high-resolution volumetric imaging tool that provides imaging evaluations for many preclinical applications. However, the relatively high cumulative radiation dose from micro-CT scans could lead to detrimental influence on the experimental outcomes or even the damages of specimens. Interior micro-computed tomography (micro- CT) produces exact tomographic images of an interior region-of-interest (ROI) embedded within an object from truncated projection data. It holds promises for many biomedical applications with significantly reduced radiation doses. Here, we present our first implementation of an interior micro-CT system using a carbon nanotube (CNT) field-emission microfocus x-ray source. The system has two modes - interior micro-CT mode and global micro-CT mode, which is realized with a detachable x-ray beam collimator at the source side. The interior mode has an effective field-of-view (FOV) of about 10mm in diameter, while for the global mode the FOV is about 40mm in diameter. We acquired CT data in these two modes from a mouse-sized phantom, and compared the reconstructed image qualities and the associated radiation exposures. Interior ROI reconstruction was achieved by using our in-house developed reconstruction algorithm. Overall, interior micro-CT demonstrated comparable image quality to the conventional global micro-CT. Radiation doses measured by an ion chamber show that interior micro-CT yielded significant dose reduction (up to 83%).

  11. [Intraoperative CT imaging system using a mobile CT scanner gantry mounted on floor-embedded rails for neurosurgery].

    PubMed

    Kabuto, M; Kubota, T; Kobayashi, H; Handa, Y; Sato, K; Ishii, H; Takeuchi, H; Uno, H; Arishima, H; Ido, K; Ueda, Y; Adachi, M; Ishida, M; Hasegawa, Y; Yanagimoto, M; Goto, Y

    1998-11-01

    Many neurosurgeons prefer to use intraoperative computed tomographic (CT) scanning, when possible, to check whether there is residual lesion or unexpected bleeding. We report a practical intraoperative CT imaging system using a high-speed CT scanner installed in the operating room along with a digitally controlled neurosurgical operating table. We designed a rail-track system to mobilize the CT gantry. The gantry is fixed onto a motorized carrier that can be moved smoothly on a rail-track embedded in the floor and with a maximum reach of 2.85 m from the room's wall to the operating table. The longitudinal motion of the operating table is easily adjusted by a foot switch from manual control to automatic control directly from the CT scanner's computer like an ordinary CT scanner bed in increments of 2, 5 or 10 mm during CT scanning. Either a carbon-made radiolucent head frame or carbon-made head plate is used as a headrest. Using this CT scanner system, pre- and intraoperative CT scannings were performed on 46 patients with brain tumors, cervical lesions or other intracranial lesions. We could operate on the patient with enough working space between the mobile CT gantry and the operating table for microneurosurgery. We could obtain intraoperative CT imaging of a patient on the operating table while the surgical wound remained open, the surgical drapes kept in place, and the surgical position unchanged, saving time in intraoperative CT scanning and preparation for further surgery when needed. This intraoperative CT imaging system installed in the operating room should be useful for neurosurgery. PMID:9866126

  12. Clinical value of coronary bypass graft evaluation with CT

    SciTech Connect

    Godwin, J.D.; Califf, R.M.; Korobkin, M.; Moore, A.V.; Breiman, R.S.; Kong, Y.

    1983-04-01

    Computed tomography (CT) has a reported accuracy of 45%-97% in assessment of patency of coronary artery bypass grafts. Dynamic CT was done in 26 patients (47 grafts) with recurrent cardiac symptoms after graft surgery. Although CT was 79% accurate (with selective angiography as the standard), the authors do not believe that it provides sufficient information for the assessment of symptomatic patients. Four patients had high-grade stenoses in their grafts, and 50% of patients had significant progression of atherosclerosis in their native coronary arteries. Neither of these conditions could be detected by CT. The clinical contribution of CT will probably be greatest for routine screening of asymptomatic patients soon after operation. Technical problems with CT scanning for graft patency are discussed.

  13. Korean Guidelines for the Appropriate Use of Cardiac CT

    PubMed Central

    Kim, Young Jin; Kim, Sung Mok; Kim, Jeong A; Yang, Dong Hyun; Hong, Yoo Jin

    2015-01-01

    The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease. PMID:25741189

  14. Multidetector CT for Penetrating Torso Trauma: State of the Art.

    PubMed

    Dreizin, David; Munera, Felipe

    2015-11-01

    The use of computed tomography (CT) for hemodynamically stable victims of penetrating torso trauma continues to increase but remains less singular to the work-up than in blunt trauma. Research in this area has focused on the incremental benefits of CT within the context of evolving diagnostic algorithms and in conjunction with techniques such as laparoscopy, endoscopy, and angiographic intervention. This review centers on the current state of multidetector CT as a triage tool for penetrating torso trauma and the primacy of trajectory evaluation in diagnosis, while emphasizing diagnostic challenges that have lingered despite tremendous technological advances since CT was first used in this setting 3 decades ago. As treatment strategies have also changed considerably over the years in parallel with advances in CT, current management implications of organ-specific injuries depicted at multidetector CT are also discussed. PMID:26492022

  15. CT and MRI in the Evaluation of Thoracic Aortic Diseases

    PubMed Central

    2013-01-01

    Computed tomography (CT) and magnetic resonance imaging (MRI) are the most commonly used imaging examinations to evaluate thoracic aortic diseases because of their high spatial and temporal resolutions, large fields of view, and multiplanar imaging reconstruction capabilities. CT and MRI play an important role not only in the diagnosis of thoracic aortic disease but also in the preoperative assessment and followup after treatment. In this review, the CT and MRI appearances of various acquired thoracic aortic conditions are described and illustrated. PMID:24396601

  16. Pancreatic changes in cystic fibrosis: CT and sonographic appearances

    SciTech Connect

    Daneman, A.; Gaskin, K.; Martin, D.J.; Cutz, E.

    1983-10-01

    The computed tomographic (CT) and sonographic appearances of the late stages of pancreatic damage in three patients with cystic fibrosis are illustrated. All three had severe exocrine pancreatic insufficiency with steatorrhea. In two patients CT revealed complete fatty replacement of the entire pancreas. In the third, increased echogenicity of the pancreas on sonography and the inhomogeneous attenuation on CT were interpreted as being the result of a combination of fibrosis, fatty replacement, calcification, and probable cyst formation.

  17. Statistical atlas based extrapolation of CT data

    NASA Astrophysics Data System (ADS)

    Chintalapani, Gouthami; Murphy, Ryan; Armiger, Robert S.; Lepisto, Jyri; Otake, Yoshito; Sugano, Nobuhiko; Taylor, Russell H.; Armand, Mehran

    2010-02-01

    We present a framework to estimate the missing anatomical details from a partial CT scan with the help of statistical shape models. The motivating application is periacetabular osteotomy (PAO), a technique for treating developmental hip dysplasia, an abnormal condition of the hip socket that, if untreated, may lead to osteoarthritis. The common goals of PAO are to reduce pain, joint subluxation and improve contact pressure distribution by increasing the coverage of the femoral head by the hip socket. While current diagnosis and planning is based on radiological measurements, because of significant structural variations in dysplastic hips, a computer-assisted geometrical and biomechanical planning based on CT data is desirable to help the surgeon achieve optimal joint realignments. Most of the patients undergoing PAO are young females, hence it is usually desirable to minimize the radiation dose by scanning only the joint portion of the hip anatomy. These partial scans, however, do not provide enough information for biomechanical analysis due to missing iliac region. A statistical shape model of full pelvis anatomy is constructed from a database of CT scans. The partial volume is first aligned with the statistical atlas using an iterative affine registration, followed by a deformable registration step and the missing information is inferred from the atlas. The atlas inferences are further enhanced by the use of X-ray images of the patient, which are very common in an osteotomy procedure. The proposed method is validated with a leave-one-out analysis method. Osteotomy cuts are simulated and the effect of atlas predicted models on the actual procedure is evaluated.

  18. Nasolacrimal Polyurethane Stent: Complications with CT Correlation

    SciTech Connect

    Pinto, Isabel T.; Paul, Laura; Grande, Carlos

    1998-11-15

    Purpose: To evaluate initial results in patients with epiphora secondary to obstruction of the nasolacrimal duct treated by placement of a polyurethane stent, and to discuss the technical problems and complications arising during the procedure, with visualization of the anatomy of the drainage apparatus using computed tomography (CT). Methods: We inserted 20 polyurethane Song stents under fluoroscopic guidance after dacryocystography in 19 patients with grade 3-4 epiphora caused by idiopathic obstruction of the nasolacrimal duct. CT scans were obtained following stent placement in all patients. Results: We focus on the technical problems and complications that arose during these procedures. During negotiation of the guidewire past the obstruction at the level of the junction of the duct with the lacrimal sac, the guidewire created a false passage in a posterior suborbital direction in two cases and towards the posterior midline in another. In all cases the guidewire was withdrawn and reinserted through the proper anatomic route without further difficulty or complications. In two cases the stent was improperly positioned wholly or partially outside the nasolacrimal system (one medially, one posteriorly). In one case the stent was removed and reinserted; in the other it remains in place and functional. CT was performed in all these cases to ensure proper anatomic alignment and determine what had gone wrong. The epiphora was completely resolved in 13 cases and partially relieved in four; there were three cases of stent obstruction. Epistaxis of short duration (1 hr) occurred in seven patients and headache in one. Conclusions: Treatment of epiphora with polyurethane stents is a technique that is well tolerated by patients and achieves a high success rate, yet problems in placement may be encountered. Though no major consequences for patients are involved, cognizance of such difficulties is important to avoid incorrect positioning of stents.

  19. Fast iterative reconstructions for animal CT

    NASA Astrophysics Data System (ADS)

    Huang, H.-M.; Hsiao, I.-T.; Jan, M.-L.

    2009-06-01

    For iterative x-ray computed tomography (CT) reconstruction, the convex algorithm combined with ordered subset (OSC) [1] is a relatively fast algorithm and has shown its potential for low-dose situations. But it needs one forward projection and two backprojections per iteration. Unlike convex algorithm, the gradient algorithm only requires one forward projection and one backprojection per iteration. Here, we applied ordered subsets of projection data to a modified gradient algorithm. In order to further reduce computation time, the new algorithm, the ordered subset gradient (OSG) algorithm, can be adjusted with a step size. We also implemented another OS-type algorithm called OSTR. The OSG algorithm is compared with OSC algorithm and OSTR algorithm using three-dimensional simulated helical cone-beam CT data. The performance is evaluated in terms of log-likelihood, contrast recovery, and bias-variance studies. Results show that images of OSG has compatible visual image quality to those of OSC and OSTR, but in the resolution and bias-variance studies, OSG seems to reach stable values with faster speed. In particular, OSTR has better recovery in a smoother region, but both OSG and OSC have better recovery in the high-frequency regions. Moreover, in terms of log likelihood with respect to computation time, OSG has faster convergence rate than that of OSC and similar to that of OSTR. We conclude that OSG has potential to provide comparable image quality and is more computationally efficient, and thus could be suitable for low-dose, helical cone-beam CT image reconstruction.

  20. Patient radiation doses for electron beam CT

    SciTech Connect

    Castellano, Isabel A.; Dance, David R.; Skinner, Claire L.; Evans, Phil M.

    2005-08-15

    A Monte Carlo based computer model has been developed for electron beam computed tomography (EBCT) to calculate organ and effective doses in a humanoid hermaphrodite phantom. The program has been validated by comparison with experimental measurements of the CT dose index in standard head and body CT dose phantoms; agreement to better than 8% has been found. The robustness of the model has been established by varying the input parameters. The amount of energy deposited at the 12:00 position of the standard body CT dose phantom is most susceptible to rotation angle, whereas that in the central region is strongly influenced by the beam quality. The program has been used to investigate the changes in organ absorbed doses arising from partial and full rotation about supine and prone subjects. Superficial organs experience the largest changes in absorbed dose with a change in subject orientation and for partial rotation. Effective doses for typical clinical scan protocols have been calculated and compared with values obtained using existing dosimetry techniques based on full rotation. Calculations which make use of Monte Carlo conversion factors for the scanner that best matches the EBCT dosimetric characteristics consistently overestimate the effective dose in supine subjects by typically 20%, and underestimate the effective dose in prone subjects by typically 13%. These factors can therefore be used to correct values obtained in this way. Empirical dosimetric techniques based on the dose-length product yield errors as great as 77%. This is due to the sensitivity of the dose length product to individual scan lengths. The magnitude of these errors is reduced if empirical dosimetric techniques based on the average absorbed dose in the irradiated volume (CTDI{sub vol}) are used. Therefore conversion factors specific to EBCT have been calculated to convert the CTDI{sub vol} to an effective dose.

  1. Neural network and its application to CT imaging

    SciTech Connect

    Nikravesh, M.; Kovscek, A.R.; Patzek, T.W.

    1997-02-01

    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.

  2. Excessive Dynamic Airway Collapse Detected Using Nondynamic CT.

    PubMed

    Harada, Yukinori; Kondo, Tomoo

    2016-01-01

    Excessive dynamic airway collapse (EDAC) has been diagnosed using dynamic CT during inspiration and expiration. We herein report an asthma patient with EDAC that was detected incidentally using nondynamic CT. The patient presented with wheezing, cough and mild fever. Treatment for the asthma did not improve her wheeze. CT revealed tracheal narrowing and bulging of the posterior bronchial wall. The patient was diagnosed with EDAC by bronchoscopy. Her wheeze improved with continuous positive airway pressure therapy. Clinicians should be aware of the airway shape when performing nondynamic CT in refractory asthma patients because recognizing the existence of EDAC may help when deciding on the treatment strategy. PMID:27250056

  3. Soft tissue imaging with photon counting spectroscopic CT

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.

    2015-03-01

    The purpose of this work was experimental investigation of photon counting spectroscopic CT (PCS-CT) imaging of anatomical soft tissue with clinically relevant size. The imaging experiments were performed using a spectroscopic CT system based on CdZnTe photon counting detector with two rows of pixels, 256 pixels in each row, 1  ×  1 mm2 pixel size, and 25.6 cm detector length. The detector could split the x-ray energy spectrum to 5 regions (energy bins), and acquire 5 multi-energy (spectroscopic) CT images in a single CT scan. A sample of round shaped anatomical soft tissue of 14 cm diameter including lean and fat was used for imaging. To avoid the negative effect of anatomical noise on quantitative analysis, a spectroscopic CT phantom with tissue equivalent solid materials was used. The images were acquired at 60, 90, and 120 kVp tube voltages, and spectroscopic image series were acquired with 3 and 5 energy bins. Spectroscopic CT numbers were introduced and used to evaluate an energy selective image series. The anatomical soft tissue with 14 cm diameter was visualized with good quality and without substantial artifacts by the photon counting spectroscopic CT system. The effects of the energy bin crosstalk on spectroscopic CT numbers were quantified and analyzed. The single and double slice PCS-CT images were acquired and compared. Several new findings were observed, including the effect of soft tissue non-uniformity on image artifacts, unique status of highest energy bin, and material dependent visualization in spectroscopic image series. Fat-lean decomposition was performed using dual energy subtraction and threshold segmentation methods, and compared. Using K-edge filtered x-rays improved fat-lean decomposition as compared to conventional x-rays. Several new and important aspects of the PCS-CT were investigated. These include imaging soft tissue with clinically relevant size, single- and double-slice PCS-CT imaging, using spectroscopic CT

  4. RONI Based Secured and Authenticated Indexing of Lung CT Images

    PubMed Central

    Jasmine Selvakumari Jeya, I.; Suganthi, J.

    2015-01-01

    Medical images need to be transmitted with the patient's information without altering the image data. The present paper discusses secured indexing of lung CT image (SILI) which is a secured way of indexing the lung CT images with the patient information. Authentication is provided using the sender's logo information and the secret key is used for embedding the watermark into the host image. Watermark is embedded into the region of Noninterest (RONI) of the lung CT image. RONI is identified by segmenting the lung tissue from the CT scan image. The experimental results show that the proposed approach is robust against unauthorized access, noise, blurring, and intensity based attacks. PMID:26078782

  5. RONI Based Secured and Authenticated Indexing of Lung CT Images.

    PubMed

    Jasmine Selvakumari Jeya, I; Suganthi, J

    2015-01-01

    Medical images need to be transmitted with the patient's information without altering the image data. The present paper discusses secured indexing of lung CT image (SILI) which is a secured way of indexing the lung CT images with the patient information. Authentication is provided using the sender's logo information and the secret key is used for embedding the watermark into the host image. Watermark is embedded into the region of Noninterest (RONI) of the lung CT image. RONI is identified by segmenting the lung tissue from the CT scan image. The experimental results show that the proposed approach is robust against unauthorized access, noise, blurring, and intensity based attacks. PMID:26078782

  6. Dual-energy CT imaging of thoracic malignancies

    PubMed Central

    Zhang, Long Jiang; Yang, Gui Fen; Wu, Sheng Yong; Lu, Guang Ming; Schoepf, U. Joseph

    2013-01-01

    Abstract Computed tomography (CT) plays a pivotal role in the detection, characterization, and staging of lung cancer and other thoracic malignancies. Since the introduction of clinically viable dual-energy CT techniques, substantial evidence has accumulated on the use of this modality for imaging chest malignancies. This article describes the principles of dual-energy CT along with suitable image acquisition, reconstruction, and postprocessing strategies for oncologic applications in the chest. The potential of dual-energy CT techniques for the detection, characterization, staging, and surveillance of chest malignancy, as well as the limitations of this modality are discussed. PMID:23470989

  7. [Application of computed tomography (CT) examination for forensic medicine].

    PubMed

    Urbanik, Andrzej; Chrzan, Robert

    2013-01-01

    The aim of the study is to present a own experiences in usage of post mortem CT examination for forensic medicine. With the help of 16-slice CT scanner 181 corpses were examined. Obtained during acquisition imaging data are later developed with dedicated programmes. Analyzed images were extracted from axial sections, multiplanar reconstructions as well as 3D reconstructions. Gained information helped greatly when classical autopsy was performed by making it more accurate. A CT scan images recorded digitally enable to evaluate corpses at any time, despite processes of putrefaction or cremation. If possible CT examination should precede classical autopsy. PMID:23944089

  8. CT detection of occult pneumothorax in head trauma

    SciTech Connect

    Tocino, I.M.; Miller, M.H.; Frederick, P.R.; Bahr, A.L.; Thomas, F.

    1984-11-01

    A prospective evaluation for occult pneumothorax was performed in 25 consecutive patients with serious head trauma by combining a limited chest CT examination with the emergency head CT examination. Of 21 pneuomothoraces present in 15 patients, 11 (52%) were found only by chest CT and were not identified clinically or by supine chest radiograph. Because of pending therapeutic measures, chest tubes were placed in nine of the 11 occult pneumothoraces, regardless of the volume. Chest CT proved itself as the most sensitive method for detection of occult pneumothorax, permitting early chest tube placement to prevent transition to a tension pneumothorax during subsequent mechanical ventilation or emergency surgery under general anesthesia.

  9. Soft tissue imaging with photon counting spectroscopic CT.

    PubMed

    Shikhaliev, Polad M

    2015-03-21

    The purpose of this work was experimental investigation of photon counting spectroscopic CT (PCS-CT) imaging of anatomical soft tissue with clinically relevant size. The imaging experiments were performed using a spectroscopic CT system based on CdZnTe photon counting detector with two rows of pixels, 256 pixels in each row, 1  ×  1 mm(2) pixel size, and 25.6 cm detector length. The detector could split the x-ray energy spectrum to 5 regions (energy bins), and acquire 5 multi-energy (spectroscopic) CT images in a single CT scan. A sample of round shaped anatomical soft tissue of 14 cm diameter including lean and fat was used for imaging. To avoid the negative effect of anatomical noise on quantitative analysis, a spectroscopic CT phantom with tissue equivalent solid materials was used. The images were acquired at 60, 90, and 120 kVp tube voltages, and spectroscopic image series were acquired with 3 and 5 energy bins. Spectroscopic CT numbers were introduced and used to evaluate an energy selective image series. The anatomical soft tissue with 14 cm diameter was visualized with good quality and without substantial artifacts by the photon counting spectroscopic CT system. The effects of the energy bin crosstalk on spectroscopic CT numbers were quantified and analyzed. The single and double slice PCS-CT images were acquired and compared. Several new findings were observed, including the effect of soft tissue non-uniformity on image artifacts, unique status of highest energy bin, and material dependent visualization in spectroscopic image series. Fat-lean decomposition was performed using dual energy subtraction and threshold segmentation methods, and compared. Using K-edge filtered x-rays improved fat-lean decomposition as compared to conventional x-rays. Several new and important aspects of the PCS-CT were investigated. These include imaging soft tissue with clinically relevant size, single- and double-slice PCS-CT imaging, using spectroscopic CT

  10. Cone-beam CT: applications in orthodontics.

    PubMed

    Hechler, Steven L

    2008-10-01

    Radiographic images have always been an important part of orthodontic diagnosis and treatment planning. We have been limited by the two-dimensional nature of these radiographs as we pursue tooth movement in a three-dimensional fashion. This article shows the current and future uses and advantages of cone-beam CT in the practice of orthodontics. The use of this technology in the near future will change the way records are taken and treatment is rendered. With this added diagnostic knowledge, orthodontic treatment will assuredly become not only more high tech but also higher quality. PMID:18805230

  11. Multidetector CT of the female pelvis.

    PubMed

    Siddall, Kristina A; Rubens, Deborah J

    2005-11-01

    In the emergency room setting, multidetector detector CT (MDCT) offers rapid, noninvasive, multiplanar evaluation of female patients who have acute pelvic pain. MDCT has been integrated into several of the major trauma centers, and its use may surpass the use of ultrasound in the trauma evaluation of the pregnant patient. In the nonemergent setting, MDCT can be used to stage gynecologic malignancy and to evaluate tumor recurrence. Multiplanar MDCT has received some acceptance for evaluation of small primary tumor volume and small metastatic implants. MDCT also has a role in the evaluation of pelvic varices and suspected pelvic congestion syndrome. PMID:16253664

  12. CT of sarcomatous degeneration in neurofibromatosis

    SciTech Connect

    Coleman, B.G.; Arger, P.H.; Dalinka, M.K.; Obringer, A.C.; Raney, B.R.; Meadows, A.T.

    1983-02-01

    Neurofibromatosis is a relatively common disorder that often involves many organ systems. One of the least understood aspects of this malady is a well documented potential for sarcomatous degeneration of neurofibromas. The inability to identify patients at risk and the lack of noninvasive screening methods for symptomatic patients often leads to late diagnosis. In six of seven subsequently proven neurofibrosarcomas, CT demonstrated low-density areas that histopathologically appeared to be due to necrosis, hemorrhage, and/or cystic degeneration. The density differences within these sarcomas were enhanced by the intravenous adminstration of iodinated contrast agents.

  13. Porcelain gallbladder: ultrasound and CT appearance

    SciTech Connect

    Kane, R.A.; Jacobs, R.; Katz, J.; Costello, P.

    1984-07-01

    Nine patients with calcification of the gallbladder wall (porcelain gallbladder) were analyzed by ultrasound and the appearance correlated with the CT, radiographic, clinical, and surgical findings. Three distinct patterns were identified: (a) a hyperechoic similunar structure with acoustic shadowing posteriorly, simulating a stone-filled gallbladder devoid of bile, which was seen in 5 patients; (b) a biconvex, curvilinear echogenic structure with variable acoustic shadowing, seen in all 3 patients with carcinoma of the gallbladder; and (c) an irregular clump of echoes with posterior acoustic shadowing, seen in 1 patient. Potential pitfalls in the diagnosis of gallbladder calcification are presented, and the association between calcification and cancer is emphasized.

  14. Deformable image registration of CT and truncated cone-beam CT for adaptive radiation therapy

    NASA Astrophysics Data System (ADS)

    Zhen, Xin; Yan, Hao; Zhou, Linghong; Jia, Xun; Jiang, Steve B.

    2013-11-01

    Truncation of a cone-beam computed tomography (CBCT) image, mainly caused by the limited field of view (FOV) of CBCT imaging, poses challenges to the problem of deformable image registration (DIR) between computed tomography (CT) and CBCT images in adaptive radiation therapy (ART). The missing information outside the CBCT FOV usually causes incorrect deformations when a conventional DIR algorithm is utilized, which may introduce significant errors in subsequent operations such as dose calculation. In this paper, based on the observation that the missing information in the CBCT image domain does exist in the projection image domain, we propose to solve this problem by developing a hybrid deformation/reconstruction algorithm. As opposed to deforming the CT image to match the truncated CBCT image, the CT image is deformed such that its projections match all the corresponding projection images for the CBCT image. An iterative forward-backward projection algorithm is developed. Six head-and-neck cancer patient cases are used to evaluate our algorithm, five with simulated truncation and one with real truncation. It is found that our method can accurately register the CT image to the truncated CBCT image and is robust against image truncation when the portion of the truncated image is less than 40% of the total image. Part of this work was presented at the 54th AAPM Annual Meeting (Charlotte, NC, USA, 29 July-2 August 2012).

  15. Research on radiation exposure from CT part of hybrid camera and diagnostic CT

    NASA Astrophysics Data System (ADS)

    Solný, Pavel; Zimák, Jaroslav

    2014-11-01

    Research on radiation exposure from CT part of hybrid camera in seven different Departments of Nuclear Medicine (DNM) was conducted. Processed data and effective dose (E) estimations led to the idea of phantom verification and comparison of absorbed doses and software estimation. Anonymous data from about 100 examinations from each DNM was gathered. Acquired data was processed and utilized by dose estimation programs (ExPACT, ImPACT, ImpactDose) with respect to the type of examination and examination procedures. Individual effective doses were calculated using enlisted programs. Preserving the same procedure in dose estimation process allows us to compare the resulting E. Some differences and disproportions during dose estimation led to the idea of estimated E verification. Consequently, two different sets of about 100 of TLD 100H detectors were calibrated for measurement inside the Aldersnon RANDO Anthropomorphic Phantom. Standard examination protocols were examined using a 2 Slice CT- part of hybrid SPECT/CT. Moreover, phantom exposure from body examining protocol for 32 Slice and 64 Slice diagnostic CT scanner was also verified. Absorbed dose (DT,R) measured using TLD detectors was compared with software estimation of equivalent dose HT values, computed by E estimation software. Though, only limited number of cavities for detectors enabled measurement within the regions of lung, liver, thyroid and spleen-pancreas region, some basic comparison is possible.

  16. CT to Cone-beam CT Deformable Registration With Simultaneous Intensity Correction

    PubMed Central

    Zhen, Xin; Gu, Xuejun; Yan, Hao; Zhou, Linghong; Jia, Xun; Jiang, Steve B.

    2012-01-01

    Computed tomography (CT) to cone-beam computed tomography (CBCT) deformable image registration (DIR) is a crucial step in adaptive radiation therapy. Current intensity-based registration algorithms, such as demons, may fail in the context of CT-CBCT DIR because of inconsistent intensities between the two modalities. In this paper, we propose a variant of demons, called Deformation with Intensity Simultaneously Corrected (DISC), to deal with CT-CBCT DIR. DISC distinguishes itself from the original demons algorithm by performing an adaptive intensity correction step on the CBCT image at every iteration step of the demons registration. Specifically, the intensity correction of a voxel in CBCT is achieved by matching the first and the second moments of the voxel intensities inside a patch around the voxel with those on the CT image. It is expected that such a strategy can remove artifacts in the CBCT image, as well as ensuring the intensity consistency between the two modalities. DISC is implemented on computer graphics processing units (GPUs) in compute unified device architecture (CUDA) programming environment. The performance of DISC is evaluated on a simulated patient case and six clinical head-and-neck cancer patient data. It is found that DISC is robust against the CBCT artifacts and intensity inconsistency and significantly improves the registration accuracy when compared with the original demons. PMID:23032638

  17. Acquiring 4D Thoracic CT Scans Using Ciné CT Acquisition

    NASA Astrophysics Data System (ADS)

    Low, Daniel

    One method for acquiring 4D thoracic CT scans is to use ciné acquisition. Ciné acquisition is conducted by rotating the gantry and acquiring x-ray projections while keeping the couch stationary. After a complete rotation, a single set of CT slices, the number corresponding to the number of CT detector rows, is produced. The rotation period is typically sub second so each image set corresponds to a single point in time. The ciné image acquisition is repeated for at least one breathing cycle to acquire images throughout the breathing cycle. Once the images are acquired at a single couch position, the couch is moved to the abutting position and the acquisition is repeated. Post-processing of the images sets typically resorts the sets into breathing phases, stacking images from a specific phase to produce a thoracic CT scan at that phase. Benefits of the ciné acquisition protocol include, the ability to precisely identify the phase with respect to the acquired image, the ability to resort images after reconstruction, and the ability to acquire images over arbitrarily long times and for arbitrarily many images (within dose constraints).

  18. CT Perfusion in the Characterisation of Renal Lesions: An Added Value to Multiphasic CT

    PubMed Central

    Pozzessere, Chiara; D'Elia, Domenico; Ambrosio, Maria Raffaella; Barone, Aurora; del Vecchio, Maria Teresa

    2014-01-01

    Objective. To prospectively evaluate if computed tomography perfusion (CTp) could be a useful tool in addition to multiphasic CT in renal lesion characterisation. Materials and Methods. Fifty-eight patients that were scheduled for surgical resection of a renal mass with a suspicion of renal cell carcinoma (RCC) were enrolled. Forty-one out of 58 patients underwent total or partial nephrectomy after CTp examination, and a pathological analysis was obtained for a total of 49 renal lesions. Perfusion parameters and attenuation values at multiphasic CT for both lesion and normal cortex were analysed. All the results were compared with the histological data obtained following surgery. Results. PS and MTT values were significantly lower in malignant lesions than in the normal cortex (P < 0.001 and P = 0.011, resp.); PS, MTT, and BF values were also statistically different between oncocytomas and malignant lesions. According to ROC analysis, the accuracy, sensitivity, and specificity to predict RCC were 95.92%, 100%, and 66.7%, respectively, for CTp whereas they were 89.80%, 93.35%, and 50%, respectively, for multiphasic CT. Conclusion. A significant difference between renal cortex and tumour CTp parameter values may suggest a malignant renal lesion. CTp could represent an added value to multiphasic CT in differentiating renal cells carcinoma from oncocytoma. PMID:25184133

  19. PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning.

    PubMed

    Sattler, Bernhard; Lee, John A; Lonsdale, Markus; Coche, Emmanuel

    2010-09-01

    The positron emission tomography in combination with CT in hybrid, cross-modality imaging systems (PET/CT) gains more and more importance as a part of the treatment-planning procedure in radiotherapy. Positron emission tomography (PET), as a integral part of nuclear medicine imaging and non-invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy. By the choice of the PET-Tracer, a variety of different metabolic processes can be visualized. First and foremost, this is the glucose metabolism of a tissue as well as for instance hypoxia or cell proliferation. This paper comprises the system characteristics of hybrid PET/CT systems. Acquisition and processing protocols are described in general and modifications to cope with the special needs in radiooncology. This starts with the different position of the patient on a special table top, continues with the use of the same fixation material as used for positioning of the patient in radiooncology while simulation and irradiation and leads to special processing protocols that include the delineation of the volumes that are subject to treatment planning and irradiation (PTV, GTV, CTV, etc.). General CT acquisition and processing parameters as well as the use of contrast enhancement of the CT are described. The possible risks and pitfalls the investigator could face during the hybrid-imaging procedure are explained and listed. The interdisciplinary use of different imaging modalities implies a increase of the volume of data created. These data need to be stored and communicated fast, safe and correct. Therefore, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and

  20. CT Evaluation of Acute Pancreatitis and its Prognostic Correlation with CT Severity Index

    PubMed Central

    Gupta, Rajesh; Vyas, Mahendra Mohan; Sharma, Rakesh

    2016-01-01

    Introduction Pancreatitis is one of most complex and clinically challenging of all abdominal disorders. USG and abdominal CT are the most commonly used diagnostic imaging modalities for the evaluation of pancreas. Computed Tomography (CT) is highly accurate and sensitive than USG in both diagnosing as well as demonstrating the extent. Early assessment of the cause and severity of acute pancreatitis is of utmost importance for prompt treatment and close monitoring of patient with severe disease. CT is the imaging method of choice for assessing the extent of acute pancreatitis and for evaluating complications. Aim To assess prognostic correlation and clinical outcome of acute pancreatitis on the basis of CT severity index. Materials and Methods A prospective study of 50 cases was carried out in the Department of Radio Diagnosis, with complaint suggestive of acute pancreatitis on the basis of clinical/laboratory/ultrasonography findings were evaluated in Siemens somatom 40 slice CT. The severity of pancreatitis was scored using CT severity index, modified severity index and revised Atlanta classification and classified into mild, moderate, severe categories. Clinical follow-up of the patients was done in terms of the following parameters: Length of hospital stay, Need for surgery or percutaneous intervention, Evidence of infection in any organ system, Occurrence of organ failure- respiratory, cardiovascular, renal, hepatic and haematological system, death. The clinical outcome was compared with the currently accepted Balthazar’s CTSI and Modified Mortele’s CTSI and revised Atlanta classification in all the cases. Results Gall stone disease was most common aetiological factor seen in 40% cases, it was more common in females than males. Alcohol was second most common aetiological factor seen in 38% cases and was noted only in males. Pleural effusion was the most common extra-pancreatic complication seen in 46% cases. Balthazar grade C was the most common (40

  1. Non-Rigid Registration of Liver CT Images for CT-Guided Ablation of Liver Tumors.

    PubMed

    Luu, Ha Manh; Klink, Camiel; Niessen, Wiro; Moelker, Adriaan; Walsum, Theo van

    2016-01-01

    CT-guided percutaneous ablation for liver cancer treatment is a relevant technique for patients not eligible for surgery and with tumors that are inconspicuous on US imaging. The lack of real-time imaging and the use of a limited amount of CT contrast agent make targeting the tumor with the needle challenging. In this study, we evaluate a registration framework that allows the integration of diagnostic pre-operative contrast enhanced CT images and intra-operative non-contrast enhanced CT images to improve image guidance in the intervention. The liver and tumor are segmented in the pre-operative contrast enhanced CT images. Next, the contrast enhanced image is registered to the intra-operative CT images in a two-stage approach. First, the contrast-enhanced diagnostic image is non-rigidly registered to a non-contrast enhanced image that is conventionally acquired at the start of the intervention. In case the initial registration is not sufficiently accurate, a refinement step is applied using non-rigid registration method with a local rigidity term. In the second stage, the intra-operative CT-images that are used to check the needle position, which often consist of only a few slices, are registered rigidly to the intra-operative image that was acquired at the start of the intervention. Subsequently, the diagnostic image is registered to the current intra-operative image, using both transformations, this allows the visualization of the tumor region extracted from pre-operative data in the intra-operative CT images containing needle. The method is evaluated on imaging data of 19 patients at the Erasmus MC. Quantitative evaluation is performed using the Dice metric, mean surface distance of the liver border and corresponding landmarks in the diagnostic and the intra-operative images. The registration of the diagnostic CT image to the initial intra-operative CT image did not require a refinement step in 13 cases. For those cases, the resulting registration had a Dice

  2. SU-E-T-70: Commissioning a Multislice CT Scanner for X-Ray CT Polymer Gel Dosimetry

    SciTech Connect

    Johnston, H; Hilts, M; Jirasek, A

    2014-06-01

    Purpose: To commission a multislice computed tomography (CT) scanner for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD). Methods: Commissioning was performed for a 16-slice CT scanner using images acquired through a 1L cylinder filled with water. Additional images were collected using a single slice machine for comparison purposes. The variability in CT number associated with the anode heel effect was evaluated and used to define a new slice-by-slice background image subtraction technique. Image quality was assessed for the multislice system by comparing image noise and uniformity to that of the single slice machine. The consistency in CT number across slices acquired simultaneously using the multislice detector array was also evaluated. Finally, the variability in CT number due to increasing x-ray tube load was measured for the multislice scanner and compared to the tube load effects observed on the single slice machine. Results: Slice-by-slice background subtraction effectively removes the variability in CT number across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image quality for the multislice machine was found to be comparable to that of the single slice scanner. Further study showed CT number was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thickness examined. In addition, the multislice system was found to eliminate variations in CT number due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to imaging a large volume using a single slice scanner. Conclusion: A multislice CT scanner has been commissioning for CT PGD, allowing images of an entire dose distribution to be acquired in a matter of minutes. Funding support provided by the Natural Sciences and Engineering

  3. MR and CT image fusion of the cervical spine: a noninvasive alternative to CT-myelography

    NASA Astrophysics Data System (ADS)

    Hu, Yangqiu; Mirza, Sohail K.; Jarvik, Jeffrey G.; Heagerty, Patrick J.; Haynor, David R.

    2005-04-01

    CT-Myelography (CTM) is routinely used for planning surgery for degenerative disease of the spine, but its invasive nature, significant potential morbidity, and high costs make a noninvasive substitute desirable. We report our work on evaluating CT and MR image fusion as an alternative to CTM. Because the spine is only piecewise rigid, a multi-rigid approach to the registration of spinal CT and MR images was developed (SPIE 2004), in which the spine on CT images is first segmented into separate vertebrae, each of which is then rigidly registered with the corresponding vertebra on MR images. The results are then blended to obtain fusion images. Since they contain information from both modalities, we hypothesized that fusion images would be equivalent to CTM. To test this we selected 34 patients who had undergone MRI and CTM for degenerative disease of the cervical spine, and used the multi-rigid approach to produce fused images. A clinical vignette for each patient was created and presented along with either CT/MR fusion images or CTM images. A group of spine surgeons are asked to formulate detailed surgical plans based on each set of images, and the surgical plans are compared. A similar study assessing diagnostic agreement is being performed with neuroradiologists, who also assess the accuracy of registration. Our work to date has demonstrated the feasibility of segmentation and multi-rigid fusion in clinical cases and the acceptability of the questionnaire to physicians. Preliminary analysis of one surgeon's and one neuroradiologist"s evaluation has been performed.

  4. Comparison of CT and PET-CT based planning of radiation therapy in locally advanced pancreatic carcinoma

    PubMed Central

    Topkan, Erkan; Yavuz, Ali A; Aydin, Mehmet; Onal, Cem; Yapar, Fuat; Yavuz, Melek N

    2008-01-01

    Background To compare computed tomography (CT) with co-registered positron emission tomography-computed tomography (PET-CT) as the basis for delineating gross tumor volume (GTV) in unresectable, locally advanced pancreatic carcinoma (LAPC). Methods Fourteen patients with unresectable LAPC had both CT and PET images acquired. For each patient, two three-dimensional conformal plans were made using the CT and PET-CT fusion data sets. We analyzed differences in treatment plans and doses of radiation to primary tumors and critical organs. Results Changes in GTV delineation were necessary in 5 patients based on PET-CT information. In these patients, the average increase in GTV was 29.7%, due to the incorporation of additional lymph node metastases and extension of the primary tumor beyond that defined by CT. For all patients, the GTVCT versus GTVPET-CT was 92.5 ± 32.3 cm3 versus 104.5 ± 32.6 cm3 (p = 0.009). Toxicity analysis revealed no clinically significant differences between two plans with regard to doses to critical organs. Conclusion Co-registration of PET and CT information in unresectable LAPC may improve the delineation of GTV and theoretically reduce the likelihood of geographic misses. PMID:18808725

  5. Practical considerations for intensity modulated CT

    NASA Astrophysics Data System (ADS)

    Szczykutowicz, Timothy P.; Mistretta, Charles

    2012-03-01

    As most patients, for a given projection, contain regions of vastly different attenuation properties, the dose level is often far higher than is required for some regions and inadequate for others. In this paper, two practical issues pertaining to intensity modulated CT (IMCT) are demonstrated and their causes are theoretically derived. IMCT can be enabled using a number of various techniques. The use of a system of attenuating wedges, or dynamic beam attenuators (DBA) is considered here. The first practical issue is the presence of scatter radiation. It is shown that scatter radiation produces ring artifacts due to a mismatch in the frequency of the scatter and the DBA attenuation in the CT normalization procedure. The second practical issue concerns the generation of a uniform CNR image under different scanning geometries. It is shown that when the fluence incident on the detector is equalized, different system geometries propagate the noise differently (i.e. uniform noise projections do not correspond to uniform noise images for all scanning geometries). It is also shown that a simple data re-binning procedure (re-binning from one system geometry to another) can effectively mitigate this effect and allow for uniform noise images. In addition, a method to estimate the scatter signal is purposed that relies on assuming the scatter signal is equal on each side of individual DBA boundaries due to its low frequency nature.

  6. Quantitative normal thoracic anatomy at CT.

    PubMed

    Matsumoto, Monica M S; Udupa, Jayaram K; Tong, Yubing; Saboury, Babak; Torigian, Drew A

    2016-07-01

    Automatic anatomy recognition (AAR) methodologies for a body region require detailed understanding of the morphology, architecture, and geographical layout of the organs within the body region. The aim of this paper was to quantitatively characterize the normal anatomy of the thoracic region for AAR. Contrast-enhanced chest CT images from 41 normal male subjects, each with 11 segmented objects, were considered in this study. The individual objects were quantitatively characterized in terms of their linear size, surface area, volume, shape, CT attenuation properties, inter-object distances, size and shape correlations, size-to-distance correlations, and distance-to-distance correlations. A heat map visualization approach was used for intuitively portraying the associations between parameters. Numerous new observations about object geography and relationships were made. Some objects, such as the pericardial region, vary far less than others in size across subjects. Distance relationships are more consistent when involving an object such as trachea and bronchi than other objects. Considering the inter-object distance, some objects have a more prominent correlation, such as trachea and bronchi, right and left lungs, arterial system, and esophagus. The proposed method provides new, objective, and usable knowledge about anatomy whose utility in building body-wide models toward AAR has been demonstrated in other studies. PMID:27065241

  7. Musculoskeletal interventional radiology: ultrasound and CT.

    PubMed

    Martel Villagrán, J; Bueno Horcajadas, Á; Agrela Rojas, E

    2016-05-01

    We aim to describe imaging-guided (ultrasound and CT) interventional techniques in the musculoskeletal system that can be performed by general radiologists, whether in hospitals, primary care clinics, private offices, or other settings. The first requirement for doing these procedures is adequate knowledge of the anatomy of the musculoskeletal system. The second requirement is to inform the patient thoroughly about the technique, the risks involved, and the alternatives available in order to obtain written informed consent. The third requirement is to ensure that the procedure is performed in accordance with the principles of asepsis in relation to the puncture zone and to all the material employed throughout the procedure. The main procedures that can be done under ultrasound guidance are the following: fine needle aspiration cytology (FNAC), core needle biopsy (CNB), diagnostic and/or therapeutic arthrocentesis, drainage of juxta-articular fluid collections, drainage of abscesses, drainage of hematomas, treatment of Baker's cyst, treatment of ganglia, treatment of bursitis, infiltrations and treatment of plantar fasciitis, plantar fibrosis, epicondylitis, Achilles tendinopathy, and Morton's neuroma, puncture and lavage of calcifications in calcifying tendinopathy. We also review the following CT-guided procedures: diagnosis of spondylodiscitis, FNAC of metastases, arthrography, drainages. Finally, we also mention more complex procedures that can only be done in appropriate settings: bone biopsies, treatment of facet joint pain, radiofrequency treatment. PMID:27134018

  8. Explosive Detection in Aviation Applications Using CT

    SciTech Connect

    Martz, H E; Crawford, C R

    2011-02-15

    CT scanners are deployed world-wide to detect explosives in checked and carry-on baggage. Though very similar to single- and dual-energy multi-slice CT scanners used today in medical imaging, some recently developed explosives detection scanners employ multiple sources and detector arrays to eliminate mechanical rotation of a gantry, photon counting detectors for spectral imaging, and limited number of views to reduce cost. For each bag scanned, the resulting reconstructed images are first processed by automated threat recognition algorithms to screen for explosives and other threats. Human operators review the images only when these automated algorithms report the presence of possible threats. The US Department of Homeland Security (DHS) has requirements for future scanners that include dealing with a larger number of threats, higher probability of detection, lower false alarm rates and lower operating costs. One tactic that DHS is pursuing to achieve these requirements is to augment the capabilities of the established security vendors with third-party algorithm developers. A third-party in this context refers to academics and companies other than the established vendors. DHS is particularly interested in exploring the model that has been used very successfully by the medical imaging industry, in which university researchers develop algorithms that are eventually deployed in commercial medical imaging equipment. The purpose of this paper is to discuss opportunities for third-parties to develop advanced reconstruction and threat detection algorithms.

  9. Scatter corrections for cone beam optical CT

    NASA Astrophysics Data System (ADS)

    Olding, Tim; Holmes, Oliver; Schreiner, L. John

    2009-05-01

    Cone beam optical computed tomography (OptCT) employing the VISTA scanner (Modus Medical, London, ON) has been shown to have significant promise for fast, three dimensional imaging of polymer gel dosimeters. One distinct challenge with this approach arises from the combination of the cone beam geometry, a diffuse light source, and the scattering polymer gel media, which all contribute scatter signal that perturbs the accuracy of the scanner. Beam stop array (BSA), beam pass array (BPA) and anti-scatter polarizer correction methodologies have been employed to remove scatter signal from OptCT data. These approaches are investigated through the use of well-characterized phantom scattering solutions and irradiated polymer gel dosimeters. BSA corrected scatter solutions show good agreement in attenuation coefficient with the optically absorbing dye solutions, with considerable reduction of scatter-induced cupping artifact at high scattering concentrations. The application of BSA scatter corrections to a polymer gel dosimeter lead to an overall improvement in the number of pixel satisfying the (3%, 3mm) gamma value criteria from 7.8% to 0.15%.

  10. Quantitative analysis of airway abnormalities in CT

    NASA Astrophysics Data System (ADS)

    Petersen, Jens; Lo, Pechin; Nielsen, Mads; Edula, Goutham; Ashraf, Haseem; Dirksen, Asger; de Bruijne, Marleen

    2010-03-01

    A coupled surface graph cut algorithm for airway wall segmentation from Computed Tomography (CT) images is presented. Using cost functions that highlight both inner and outer wall borders, the method combines the search for both borders into one graph cut. The proposed method is evaluated on 173 manually segmented images extracted from 15 different subjects and shown to give accurate results, with 37% less errors than the Full Width at Half Maximum (FWHM) algorithm and 62% less than a similar graph cut method without coupled surfaces. Common measures of airway wall thickness such as the Interior Area (IA) and Wall Area percentage (WA%) was measured by the proposed method on a total of 723 CT scans from a lung cancer screening study. These measures were significantly different for participants with Chronic Obstructive Pulmonary Disease (COPD) compared to asymptomatic participants. Furthermore, reproducibility was good as confirmed by repeat scans and the measures correlated well with the outcomes of pulmonary function tests, demonstrating the use of the algorithm as a COPD diagnostic tool. Additionally, a new measure of airway wall thickness is proposed, Normalized Wall Intensity Sum (NWIS). NWIS is shown to correlate better with lung function test values and to be more reproducible than previous measures IA, WA% and airway wall thickness at a lumen perimeter of 10 mm (PI10).

  11. Functional MRI and CT biomarkers in oncology.

    PubMed

    Winfield, J M; Payne, G S; deSouza, N M

    2015-04-01

    Imaging biomarkers derived from MRI or CT describe functional properties of tumours and normal tissues. They are finding increasing numbers of applications in diagnosis, monitoring of response to treatment and assessment of progression or recurrence. Imaging biomarkers also provide scope for assessment of heterogeneity within and between lesions. A wide variety of functional parameters have been investigated for use as biomarkers in oncology. Some imaging techniques are used routinely in clinical applications while others are currently restricted to clinical trials or preclinical studies. Apparent diffusion coefficient, magnetization transfer ratio and native T1 relaxation time provide information about structure and organization of tissues. Vascular properties may be described using parameters derived from dynamic contrast-enhanced MRI, dynamic contrast-enhanced CT, transverse relaxation rate (R2*), vessel size index and relative blood volume, while magnetic resonance spectroscopy may be used to probe the metabolic profile of tumours. This review describes the mechanisms of contrast underpinning each technique and the technical requirements for robust and reproducible imaging. The current status of each biomarker is described in terms of its validation, qualification and clinical applications, followed by a discussion of the current limitations and future perspectives. PMID:25578953

  12. Development of Independent-type Optical CT

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsushi; Shiozawa, Daigoro; Rokunohe, Toshiaki; Kida, Junzo; Zhang, Wei

    Optical current transformers (optical CTs) have features that they can be made much smaller and lighter than conventional electromagnetic induction transformers by their simple structure, and contribute to improvement of equipment reliability because of their excellent surge resistance performance. Authors consider optical CTs to be next generation transformers, and are conducting research and development of optical CTs aiming to apply to measuring and protection in electric power systems. Specifically we developed an independent-type optical CT by utilizing basic data of optical CTs accumulated for large current characteristics, temperature characteristics, vibration resistance characteristics, and so on. In performance verification, type tests complying with IEC standards, such as short-time current tests, insulation tests, accuracy tests, and so on, showed good results. This report describes basic principle and configuration of optical CTs. After that, as basic characteristics of optical CTs, conditions and results of verification tests for dielectric breakdown characteristics of sensor fibers, large current characteristics, temperature characteristics, and vibration resistance characteristics are described. Finally, development outline of the independent-type optical CT aiming to apply to all digital substation and its type tests results are described.

  13. An Onboarding Program for the CT Department.

    PubMed

    Baldwin, Brandi

    2016-01-01

    Healthcare organizations compete for employees in the same way television networks compete for new talent. Organizations also compete over experience, knowledge, and skills new employees bring with them. Organizations that can acclimate a new employee into the social and performance aspects of a new job the quickest create a substantial competitive advantage. Onboarding is the term used for orientation or organizational socialization where new employees acquire the necessary knowledge, skills, and behaviors to fit in with a new company. Computed tomography (CT) department specific onboarding programs increase the comfort level of new employees by informing them of the supervisor's and the department's expectations. Although this article discusses CT, specifically, an onboarding program could apply to all of imaging. With the high costs that employee turnover incurs, all departments should have an orientation program that helps retain employees as well as prepare new employees for employment. Current personnel are valuable resources for offering appropriate information for successful employment in specific departments. A structured, department specific onboarding program with the full participation and support of current staff will enhance staff retention. PMID:26939295

  14. Efficient detection of polyps in CT colonography

    NASA Astrophysics Data System (ADS)

    Wolf, Matthias; Cathier, Pascal; Lakare, Sarang; Dundar, Murat; Bogoni, Luca

    2007-03-01

    Colon cancer is a widespread disease and, according to the American Cancer Society, it is estimated that in 2006 more than 55,000 people will die of colon cancer in the US. However, early detection of colorectal polyps helps to drastically reduces mortality. Computer-Aided Detection (CAD) of colorectal polyps is a tool that could help physicians finding such lesions in CT scans of the colon. In this paper, we present the first phase, candidate generation (CG), of our technique for the detection of colonic polyp candidate locations in CT colonoscopy. Since polyps typically appear as protrusions on the surface of the colon, our cutting-plane algorithm identifies all those areas that can be "cut-off" using a plane. The key observation is that for any protruding lesion there is at least one plane that cuts a fragment off. Furthermore, the intersection between the plane and the polyp will typically be small and circular. On the other hand, a plane cannot cut a small circular cross-section from a wall or a fold, due to their concave or elongated paraboloid morphology, because these structures yield cross-sections that are much larger or non-circular. The algorithm has been incorporated as part of a prototype CAD system. An analysis on a test set of more than 400 patients yielded a high per-patient sensitivity of 95% and 90% in clean and tagged preparation respectively for polyps ranging from 6mm to 20mm in size.

  15. PET/CT imaging in neuroblastoma.

    PubMed

    Piccardo, A; Lopci, E; Conte, M; Foppiani, L; Garaventa, A; Cabria, M; Villavecchia, G; Fanti, S; Cistaro, A

    2013-03-01

    123Iodine-metaiodobenzylguanidine (123I-MIBG) scintigraphy is currently the tracer of choice for neuroblastoma (NB). It has high diagnostic accuracy and prognostic value for the assessment of patients after chemotherapy. A positive 123I-MIBG scan is also used for the basis of targeted radionuclide therapy with 131I-MIBG. I-123 MIBG scan however has some limitations which should be taken into account. Moreover the reasons for false negative MIBG results have not been entirely elucidated. Meticulous correlation with radiological examinations and recognition of the normal distribution pattern of 123I-MIBG in children is vital to obtain optimal results. With its technical superiorities, positron emission tomography/computed tomography (PET/CT) can be successfully introduced into the diagnostic workup of NB. Different PET tracers have been offered for imaging in patients with NB, and the efficacy of this modality has been compared with that of 123I-MIBG scan. Our review aims to analyze the present role of PET/CT imaging and radiopharmaceuticals in NB. PMID:23474633

  16. Algorithms for optimizing CT fluence control

    NASA Astrophysics Data System (ADS)

    Hsieh, Scott S.; Pelc, Norbert J.

    2014-03-01

    The ability to customize the incident x-ray fluence in CT via beam-shaping filters or mA modulation is known to improve image quality and/or reduce radiation dose. Previous work has shown that complete control of x-ray fluence (ray-by-ray fluence modulation) would further improve dose efficiency. While complete control of fluence is not currently possible, emerging concepts such as dynamic attenuators and inverse-geometry CT allow nearly complete control to be realized. Optimally using ray-by-ray fluence modulation requires solving a very high-dimensional optimization problem. Most optimization techniques fail or only provide approximate solutions. We present efficient algorithms for minimizing mean or peak variance given a fixed dose limit. The reductions in variance can easily be translated to reduction in dose, if the original variance met image quality requirements. For mean variance, a closed form solution is derived. The peak variance problem is recast as iterated, weighted mean variance minimization, and at each iteration it is possible to bound the distance to the optimal solution. We apply our algorithms in simulations of scans of the thorax and abdomen. Peak variance reductions of 45% and 65% are demonstrated in the abdomen and thorax, respectively, compared to a bowtie filter alone. Mean variance shows smaller gains (about 15%).

  17. Racial Differences in CT Phenotypes in COPD

    PubMed Central

    Hansel, Nadia N.; Washko, George R.; Foreman, Marilyn G.; Han, MeiLan K.; Hoffman, Eric A.; DeMeo, Dawn L.; Barr, R. Graham; Van Beek, Edwin J.R.; Kazerooni, Ella A.; Wise, Robert A.; Brown, Robert H.; Black-Shinn, Jennifer; Hokanson, John E.; Hanania, Nicola A.; Make, Barry; Silverman, Edwin K.; Crapo, James D.; Dransfield, Mark T.

    2015-01-01

    Background Whether African Americans (AA) are more susceptible to COPD than non-Hispanic Whites (NHW) and whether racial differences in disease phenotype exist is controversial. The objective is to determine racial differences in the extent of emphysema and airway remodeling in COPD. Methods First, 2,500 subjects enrolled in the COPDGene study were used to evaluate racial differences in quantitative CT (QCT) parameters of % emphysema, air trapping and airway wall thickness. Independent variables studied included race, age, gender, education, BMI, pack-years, smoking status, age at smoking initiation, asthma, previous work in dusty job, CT scanner and center of recruitment. Results Of the 1,063 subjects with GOLD Stage II-IV COPD, 200 self-reported as AA. AAs had a lower mean % emphysema (13.1 % vs. 16.1%, p = 0.005) than NHW and proportionately less emphysema in the lower lung zones. After adjustment for covariates, there was no statistical difference by race in air trapping or airway wall thickness. Measured QCT parameters were more predictive of poor functional status in NHWs compared to AAs. Conclusions AAs have less emphysema than NHWs but the same degree of airway disease. Additional factors not easily assessed by current QCT techniques may account for the poor functional status in AAs. PMID:23413893

  18. 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.

  19. Iterative CT shading correction with no prior information

    NASA Astrophysics Data System (ADS)

    Wu, Pengwei; Sun, Xiaonan; Hu, Hongjie; Mao, Tingyu; Zhao, Wei; Sheng, Ke; Cheung, Alice A.; Niu, Tianye

    2015-11-01

    Shading artifacts in CT images are caused by scatter contamination, beam-hardening effect and other non-ideal imaging conditions. The purpose of this study is to propose a novel and general correction framework to eliminate low-frequency shading artifacts in CT images (e.g. cone-beam CT, low-kVp CT) without relying on prior information. The method is based on the general knowledge of the relatively uniform CT number distribution in one tissue component. The CT image is first segmented to construct a template image where each structure is filled with the same CT number of a specific tissue type. Then, by subtracting the ideal template from the CT image, the residual image from various error sources are generated. Since forward projection is an integration process, non-continuous shading artifacts in the image become continuous signals in a line integral. Thus, the residual image is forward projected and its line integral is low-pass filtered in order to estimate the error that causes shading artifacts. A compensation map is reconstructed from the filtered line integral error using a standard FDK algorithm and added back to the original image for shading correction. As the segmented image does not accurately depict a shaded CT image, the proposed scheme is iterated until the variation of the residual image is minimized. The proposed method is evaluated using cone-beam CT images of a Catphan©600 phantom and a pelvis patient, and low-kVp CT angiography images for carotid artery assessment. Compared with the CT image without correction, the proposed method reduces the overall CT number error from over 200 HU to be less than 30 HU and increases the spatial uniformity by a factor of 1.5. Low-contrast object is faithfully retained after the proposed correction. An effective iterative algorithm for shading correction in CT imaging is proposed that is only assisted by general anatomical information without relying on prior knowledge. The proposed method is thus practical

  20. Calibration free beam hardening correction for cardiac CT perfusion imaging

    NASA Astrophysics Data System (ADS)

    Levi, Jacob; Fahmi, Rachid; Eck, Brendan L.; Fares, Anas; Wu, Hao; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

    2016-03-01

    Myocardial perfusion imaging using CT (MPI-CT) and coronary CTA have the potential to make CT an ideal noninvasive gate-keeper for invasive coronary angiography. However, beam hardening artifacts (BHA) prevent accurate blood flow calculation in MPI-CT. BH Correction (BHC) methods require either energy-sensitive CT, not widely available, or typically a calibration-based method. We developed a calibration-free, automatic BHC (ABHC) method suitable for MPI-CT. The algorithm works with any BHC method and iteratively determines model parameters using proposed BHA-specific cost function. In this work, we use the polynomial BHC extended to three materials. The image is segmented into soft tissue, bone, and iodine images, based on mean HU and temporal enhancement. Forward projections of bone and iodine images are obtained, and in each iteration polynomial correction is applied. Corrections are then back projected and combined to obtain the current iteration's BHC image. This process is iterated until cost is minimized. We evaluate the algorithm on simulated and physical phantom images and on preclinical MPI-CT data. The scans were obtained on a prototype spectral detector CT (SDCT) scanner (Philips Healthcare). Mono-energetic reconstructed images were used as the reference. In the simulated phantom, BH streak artifacts were reduced from 12+/-2HU to 1+/-1HU and cupping was reduced by 81%. Similarly, in physical phantom, BH streak artifacts were reduced from 48+/-6HU to 1+/-5HU and cupping was reduced by 86%. In preclinical MPI-CT images, BHA was reduced from 28+/-6 HU to less than 4+/-4HU at peak enhancement. Results suggest that the algorithm can be used to reduce BHA in conventional CT and improve MPI-CT accuracy.

  1. Coronary CT angiography: current status and continuing challenges.

    PubMed

    Sun, Z; Choo, G H; Ng, K H

    2012-05-01

    Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted. PMID:22253353

  2. Current and Novel Imaging Techniques in Coronary CT.

    PubMed

    Machida, Haruhiko; Tanaka, Isao; Fukui, Rika; Shen, Yun; Ishikawa, Takuya; Tate, Etsuko; Ueno, Eiko

    2015-01-01

    Multidetector coronary computed tomography (CT), which is widely performed to assess coronary artery disease noninvasively and accurately, provides excellent image quality. Use of electrocardiography (ECG)-controlled tube current modulation and low tube voltage can reduce patient exposure to nephrotoxic contrast media and carcinogenic radiation when using standard coronary CT with a retrospective ECG-gated helical scan. Various imaging techniques are expected to overcome the limitations of standard coronary CT, which also include insufficient spatial and temporal resolution, beam-hardening artifacts, limited coronary plaque characterization, and an inability to allow functional assessment of coronary stenosis. Use of a step-and-shoot scan, iterative reconstruction, and a high-pitch dual-source helical scan can further reduce radiation dose. Dual-energy CT can improve contrast medium enhancement and reasonably reduce the contrast dose when combined with noise reduction with the use of iterative reconstruction. High-definition CT can improve spatial resolution and diagnostic evaluation of small or peripheral coronary vessels and coronary stents. Dual-source CT and a motion correction algorithm can improve temporal resolution and reduce coronary motion artifacts. Whole-heart coverage with 320-detector CT and an intelligent boundary registration algorithm can eliminate stair-step artifacts. By decreasing beam hardening and enabling material decomposition, dual-energy CT is expected to remove or reduce the depiction of coronary calcification to improve intraluminal evaluation of calcified vessels and to provide detailed analysis of coronary plaque components and accurate qualitative and quantitative assessment of myocardial perfusion. Fractional flow reserve derived from coronary CT is a state-of-the-art noninvasive technique for accurately identifying myocardial ischemia beyond coronary CT. Understanding these techniques is important to enhance the value of coronary CT

  3. Coronary CT angiography: current status and continuing challenges

    PubMed Central

    Sun, Z; Choo, G H; Ng, K H

    2012-01-01

    Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted. PMID:22253353

  4. CT evaluation of tarsometatarsal fracture-dislocation injuries

    SciTech Connect

    Goiney, R.C.; Connell, D.G.; Nichols, D.M.

    1985-05-01

    Fracture-dislocation in the tarsometatarsal region (Lisfranc) may be subtle and difficult to recognize on standard radiographic projections. Computed tomography (CT) was used to study the normal anatomy of the forefoot and to evaluate three patients with suspected tarsometatarsal fracture dislocation. The advantages of CT in the evaluation of forefoot trauma are emphasized.

  5. Design and construction of the 1st proton CT scanner

    NASA Astrophysics Data System (ADS)

    Coutrakon, G.; Bashkirov, V.; Hurley, F.; Johnson, R.; Rykalin, V.; Sadrozinski, H.; Schulte, R.

    2013-04-01

    This paper discusses the design and operation of the 1st proton CT scanner for 3D imaging. Reduction of proton range uncertainties and improved dose accuracy in the patient for treatment planning are central goals. A central CT slice acquired by reconstruction of 134 million proton tracks through a 14 cm spherical polystyrene phantom with high and low density inserts is presented.

  6. Adrenal pseudotumors on CT due to dilated portosystemic veins

    SciTech Connect

    Mitty, H.M.; Cohen, B.A.; Sprayregen, S.; Schwartz, K.

    1983-10-01

    The adrenal and periadrenal venous systems are part of the portosystemic collateral pathways that may enlarge in portal hypertension. The cross-sectional image of the resulting enlarged venous channels may simulate an adrenal msss. Three examples of such computed tomographic (CT) scans are presented with selective venographic correlation. Patients with portal hypertension and suspected adrenal pathology may require enhanced or dynamic CT scans.

  7. The role of SPECT/CT in skeletal malignancies.

    PubMed

    Ghosh, Partha

    2014-04-01

    Bone scintigraphy is widely used for the detection of skeletal metastases, particularly in prostate and breast cancer. Although planar imaging is widely used, single-photon emission computed tomography (SPECT) imaging has demonstrated higher sensitivity. SPECT/CT imaging with the integration of CT and SPECT gantries has enhanced bone scintigraphy by providing accurate lesion localization and characterization of equivocal and solitary bone lesions. The key impact has been enhanced diagnostic confidence in the differentiation of benign from malignant skeletal lesions made possible by accurate localization of lesions to facet joints, vertebral bodies, or pedicles due to the exact coregistration of CT and SPECT as well as consideration of sclerosis or lysis within the lesion seen on CT. Several studies comparing planar, SPECT, and SPECT/CT in equivocal lesions have demonstrated a substantial improvement in specificity with SPECT/CT. This review highlights the key studies demonstrating the value of SPECT/CT in the evaluation of skeletal malignancies and shows clinical examples illustrating the impact of SPECT/CT in improved localization and characterization of skeletal lesions. PMID:24715449

  8. FDG PET/CT in Hepatoid Adenocarcinoma of the Lung.

    PubMed

    Wang, Shouyang; Li, Mengxi; Chen, Huai; Li, Jianyu; Zeng, Qingsi

    2016-07-01

    A right upper lung mass was incidentally found on a chest radiograph in a routine health examination in a 56-year-old man. The mass showed mild heterogeneous enhancement on contrast chest CT images and intense FDG uptake on PET/CT images. Pathological examination demonstrated hepatoid adenocarcinoma in the lung. PMID:27124679

  9. 75 FR 78163 - Drawbridge Operation Regulations; Mystic River, Mystic, CT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulations; Mystic River, Mystic, CT AGENCY... the Route 1 Bridge across the Mystic River, mile 2.8, at Mystic, CT. The deviation is necessary...

  10. WebCT Can Benefit You and Your Students

    ERIC Educational Resources Information Center

    Hagler, Barbara E.

    2004-01-01

    Teachers should consider using web-based platform, such as WebCT, to enhance their regular face-to-face classes. WebCT and other similar systems offer many benefits to teachers and students in traditional settings. Students can benefit by being able view slides or notes they missed in the regular classroom. They can also benefit from the increased…

  11. 21 CFR 1020.33 - Computed tomography (CT) equipment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Computed tomography (CT) equipment. 1020.33 Section 1020.33 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) RADIOLOGICAL HEALTH PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING PRODUCTS § 1020.33 Computed tomography (CT) equipment....

  12. 11. Whitney's Armory, Near New Haven, Ct., 1842 Photocopied from ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Whitney's Armory, Near New Haven, Ct., 1842 Photocopied from a woodcut in Henry Howe, Memoirs of the Most Eminent American Mechanics (New York, 1842), p. 124. The best early view of the filing shop and its raceway. See footnote 58. - Eli Whitney Armory, West of Whitney Avenue, Armory Street Vicinity, Hamden, New Haven County, CT

  13. A generalized method of converting CT image to PET linear attenuation coefficient distribution in PET/CT imaging

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Wu, Li-Wei; Wei, Le; Gao, Juan; Sun, Cui-Li; Chai, Pei; Li, Dao-Wu

    2014-02-01

    The accuracy of attenuation correction in positron emission tomography scanners depends mainly on deriving the reliable 511-keV linear attenuation coefficient distribution in the scanned objects. In the PET/CT system, the linear attenuation distribution is usually obtained from the intensities of the CT image. However, the intensities of the CT image relate to the attenuation of photons in an energy range of 40 keV-140 keV. Before implementing PET attenuation correction, the intensities of CT images must be transformed into the PET 511-keV linear attenuation coefficients. However, the CT scan parameters can affect the effective energy of CT X-ray photons and thus affect the intensities of the CT image. Therefore, for PET/CT attenuation correction, it is crucial to determine the conversion curve with a given set of CT scan parameters and convert the CT image into a PET linear attenuation coefficient distribution. A generalized method is proposed for converting a CT image into a PET linear attenuation coefficient distribution. Instead of some parameter-dependent phantom calibration experiments, the conversion curve is calculated directly by employing the consistency conditions to yield the most consistent attenuation map with the measured PET data. The method is evaluated with phantom experiments and small animal experiments. In phantom studies, the estimated conversion curve fits the true attenuation coefficients accurately, and accurate PET attenuation maps are obtained by the estimated conversion curves and provide nearly the same correction results as the true attenuation map. In small animal studies, a more complicated attenuation distribution of the mouse is obtained successfully to remove the attenuation artifact and improve the PET image contrast efficiently.

  14. Accuracy of CT-based attenuation correction in PET/CT bone imaging

    NASA Astrophysics Data System (ADS)

    Abella, Monica; Alessio, Adam M.; Mankoff, David A.; MacDonald, Lawrence R.; Vaquero, Juan Jose; Desco, Manuel; Kinahan, Paul E.

    2012-05-01

    We evaluate the accuracy of scaling CT images for attenuation correction of PET data measured for bone. While the standard tri-linear approach has been well tested for soft tissues, the impact of CT-based attenuation correction on the accuracy of tracer uptake in bone has not been reported in detail. We measured the accuracy of attenuation coefficients of bovine femur segments and patient data using a tri-linear method applied to CT images obtained at different kVp settings. Attenuation values at 511 keV obtained with a 68Ga/68Ge transmission scan were used as a reference standard. The impact of inaccurate attenuation images on PET standardized uptake values (SUVs) was then evaluated using simulated emission images and emission images from five patients with elevated levels of FDG uptake in bone at disease sites. The CT-based linear attenuation images of the bovine femur segments underestimated the true values by 2.9 ± 0.3% for cancellous bone regardless of kVp. For compact bone the underestimation ranged from 1.3% at 140 kVp to 14.1% at 80 kVp. In the patient scans at 140 kVp the underestimation was approximately 2% averaged over all bony regions. The sensitivity analysis indicated that errors in PET SUVs in bone are approximately proportional to errors in the estimated attenuation coefficients for the same regions. The variability in SUV bias also increased approximately linearly with the error in linear attenuation coefficients. These results suggest that bias in bone uptake SUVs of PET tracers ranges from 2.4% to 5.9% when using CT scans at 140 and 120 kVp for attenuation correction. Lower kVp scans have the potential for considerably more error in dense bone. This bias is present in any PET tracer with bone uptake but may be clinically insignificant for many imaging tasks. However, errors from CT-based attenuation correction methods should be carefully evaluated if quantitation of tracer uptake in bone is important.

  15. Thoracic cancer imaging with PET/CT in radiation oncology

    NASA Astrophysics Data System (ADS)

    Chi, Pai-Chun Melinda

    Significance. Respiratory motion has been shown to cause artifacts in PET/CT imaging. This breathing artifact can have a significant impact on PET quantification and it can lead to large uncertainties when using PET for radiation therapy planning. We have demonstrated a promising solution to resolve the breathing artifact by acquiring respiration-averaged CT (ACT) for PET/CT. The purpose of this work was to optimize the ACT acquisition for clinical implementation and to evaluate the impact of ACT on PET/CT quantification. The hypothesis was that ACT is an effective method in removing the breathing artifact when compared to our current clinical protocol. Methods. Phase and cine approaches for acquiring ACT were investigated and the results of these two approaches were compared to the ACT generated from clinical 4DCT data sets (abbreviated as ACT10phs ). In the phase approach, ACT was generated based on combinations of selected respiratory phases; in the cine approach, ACT was generated based on cine images acquired over a fixed cine duration. The phase combination and cine duration that best approximated the ACT10phs were determined to be the optimized scanning parameters. 216 thoracic PET/CT patients were scanned with both current clinical and the ACT protocols. The effects of ACT on PET/CT quantification were assessed by comparing clinical PET/CT and ACT PET/CT using 3 metrics: PET/CT image alignment, maximum standardized uptake value (SUVmax), and threshold segmented gross tumor volume (GTV). Results. ACT10phs can be best approximated to within 2% of SUV variation by phase averaging based on 4 representative phases, and to within 3% by cine image averaging based on >3s of cine duration. We implemented the cine approach on the PET/CT scanners and acquired 216 patient data sets. 68% of patients had breathing artifacts in their clinical PET/CT and the artifacts were removed/reduced in all corresponding ACT PET/CT. PET/CT quantification for lesions <50 cm3 and

  16. CT in the diagnosis of interstitial lung disease

    SciTech Connect

    Bergin, C.J.; Mueller, N.L.

    1985-09-01

    The computed tomographic (CT) appearance of interstitial lung disease was assessed in 23 patients with known interstitial disease. These included seven patients with fibrosing alveolitis, six with silicosis, two with hypersensitivity pneumonitis, three with lymphangitic spread of tumor, two with sarcoidosis, one with rheumatoid lung disease, and two with neurofibromatosis. The CT appearance of the interstitial changes in the different disease entities was assessed. Nodules were a prominent CT feature in silicosis, sarcoidosis, and lymphangitic spread of malignancy. Distribution of nodules and associated interlobular septal thickening provided further distinguishing features in these diseases. Reticular densities were the predominant CT change in fibrosing alveolitis, rheumatoid lung disease, and extrinsic allergic alveolitis. CT can be useful in the investigation of selected instances of interstitial pulmonary disease.

  17. Primary hyperaldosteronism: comparison of CT, adrenal venography, and venous sampling

    SciTech Connect

    Geisinger, M.A.; Zelch, M.G.; Bravo, E.L.; Risius, B.F.; O'Donovan, P.B.; Borkowski, G.P.

    1983-08-01

    Twenty-nine patients with primary hyperaldosteronism were evaluated with computed tomography (CT), adrenal venous sampling, and adrenal venography. Twenty-three patients had aldosteronomas and six had bilateral adrenocortical hyperplasia. Sixteen (70%) of the adenomas were accurately located by CT. All nodules of 1.5 cm or larger diameter and 50% of nodules 1.0 to 1.4 cm in diameter were demonstrated. Nodules of less than 1.0 cm in diameter generally were not detected. High-resolution CT appeared more sensitive than standard CT (75% vs 58%). Adrenal venous sampling for aldosterone assay was the most sensitive of the three methods, localizing 22 (96%) of the 23 adenomas. Eighteen (78%) of the adenomas were identified by adrenal venography, although two patients with bilateral cortical hyperplasia were mistakenly diagnosed as having a small adenoma. No such false-positive studies were encountered with CT or adrenal venous sampling.

  18. CT and MR imaging after middle ear surgery.

    PubMed

    Kösling, S; Bootz, F

    2001-11-01

    This article describes the current value of imaging in patients after stapes surgery and surgery after chronic otitis media including cholesteatoma. Possibilities and limits of computed tomography (CT) and MRI are described and most important investigation parameters are mentioned. After otosclerosis surgery, CT is the method of first choice in detection of reasons for vertigo and/or recurrent hearing loss in the later postoperative phase. CT may show the position and condition of prosthesis, scarring around the prosthesis and otospongiotic foci. Sometimes, it gives indirect hints for perilymphatic fistulas and incus necrosis. MRI is able to document inner ear complications. CT has a high negative predictive value in cases with a free cavity after mastoidectomy. Localized opacities or total occlusion are difficult to distinguish by CT alone. MRI provides important additional information in the differentiation of cholesterol granuloma, cholesteatoma, effusion, granulation and scar tissue. PMID:11704358

  19. Hemiplegic cerebral palsy: correlation between CT morphology and clinical findings.

    PubMed

    Wiklund, L M; Uvebrant, P

    1991-06-01

    Morphological findings on CT were compared with clinical features of 111 children with hemiplegic cerebral palsy. Periventricular atrophy, interpreted as periventricular leukomalacia, was the most prevalent CT finding, although this type of lesion did not indicate severity of neurological impairment. Maldevelopments were associated with arm-dominated hemiplegia and with a wider range of clinical impairments than previously described. Cortical/subcortical atrophy, less common than presumed, indicated arm-dominated hemiplegia and was associated with more severe impairment than were other CT findings. A normal CT scan indicated leg-dominated hemiplegia and mild impairment. The morphological information obtained by CT was found to be useful for predicting clinical outcome, and was considered an important adjunct to clinical history and findings in these children. PMID:1864477

  20. CT findings in ulcerative, granulomatous, and indeterminate colitis

    SciTech Connect

    Gore, R.M.; Marn, C.S.; Kirby, D.F.; Vogelzang, R.L.; Neiman, H.L.

    1984-08-01

    Eight patients with ulcerative colitis, three with colitis indeterminate, and 15 patients with Crohn disease were studied by computed tomography (CT) to establish CT criteria for each disorder in hopes of providing a new diagnostic perspective useful in the radiographic evaluation of inflammatory colitis. The CT findings in ulcerative colitis included thickening of the colon wall, which was characterized by inhomogeneous attenuation and a target appearance of the rectum, and proliferation of perirectal fat. Bowel wall thickening with homogeneous attenuation, fistula and abscess formation, and mesenteric abnormalities were observed in patients with Crohn colitis. Patients with colitis indeterminate showed colonic changes on CT observed in both disorders. Initial experience suggests that CT can differentiate patients with well established ulcerative and Crohn colitis.

  1. Thyroid CT number and its relationship to iodine concentration

    SciTech Connect

    Iida, Y.; Konishi, J.; Harioka, T.; Misaki, T.; Endo, K.; Torizuka, K.

    1983-06-01

    Sixty-seven patients with thyroid disease and 24 normal controls were examined with computed tomography (CT). The mean CT number (Hounsfield units +/- SD) in the normal controls (118.1 +/- 12.2) was significantly higher (p < 0.001) than the mean CT number in patients with diseased thyroids, except for 2 cases of simple goiter (CT numbers 113, 132). The Graves disease (69.5 +/- 17.6) amd Hishimoto thyroiditis (61.4 +/- 9.1) were significaantly higher than those in patients with adenoma (41.7 +/- 10.6, p < 0.001), cyst (33.1 +/- 14.8, p < 0.001), or cancer (48.7 +/- 13, p < 0.01). In 14 patients studied, a significant correlation was observed between thyroid CT numbers and the iodine concentration of the tissue (r = 0.889; p < 0.001).

  2. MicroCT: Automated Analysis of CT Reconstructed Data of Home Made Explosive Materials Using the Matlab MicroCT Analysis GUI

    SciTech Connect

    Seetho, I M; Brown, W D; Kallman, J S; Martz, H E; White, W T

    2011-09-22

    This Standard Operating Procedure (SOP) provides the specific procedural steps for analyzing reconstructed CT images obtained under the IDD Standard Operating Procedures for data acquisition [1] and MicroCT image reconstruction [2], per the IDD Quality Assurance Plan for MicroCT Scanning [3]. Although intended to apply primarily to MicroCT data acquired in the HEAFCAT Facility at LLNL, these procedures may also be applied to data acquired at Tyndall from the YXLON cabinet and at TSL from the HEXCAT system. This SOP also provides the procedural steps for preparing the tables and graphs to be used in the reporting of analytical results. This SOP applies to production work - for R and D there are two other semi-automated methods as given in [4, 5].

  3. MicroCT: Semi-Automated Analysis of CT Reconstructed Data of Home Made Explosive Materials Using the Matlab MicroCT Analysis GUI

    SciTech Connect

    Seetho, I M; Brown, W D; Kallman, J S; Martz, H E; White, W T

    2011-09-22

    This Standard Operating Procedure (SOP) provides the specific procedural steps for analyzing reconstructed CT images obtained under the IDD Standard Operating Procedures for data acquisition [1] and MicroCT image reconstruction [2], per the IDD Quality Assurance Plan for MicroCT Scanning [3]. Although intended to apply primarily to MicroCT data acquired in the HEAFCAT Facility at LLNL, these procedures may also be applied to data acquired at Tyndall from the YXLON cabinet and at TSL from the HEXCAT system. This SOP also provides the procedural steps for preparing the tables and graphs to be used in the reporting of analytical results. This SOP applies to R and D work - for production applications, use [4].

  4. Effect of pitch in multislice spiral/helical CT

    NASA Astrophysics Data System (ADS)

    Wang, Ge; Vannier, Michael W.

    1999-09-01

    To understand the effect of pitch on raw data interpolation in multi-slice spiral/helical CT, and provide guidelines for scanner design and protocol optimization. Multi-slice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the detector collimation, and the table increment per X-ray source rotation. The pitch in multi-slice spiral CT is defined as the ratio of the table increment over the detector collimation. In parallel to the current framework for studying longitudinal image resolution, the central fan- beam rays of direct and opposite directions are considered, assuming a narrow cone-beam angle. Generally speaking, sampling in the Radon domain by the direct and opposite central rays is non-uniform along the longitudinal axis. Using a recently developed methodology for quantifying the sensitivity of signal reconstruction from non-uniformly sampled finite points, the effect of pitch on raw data interpolation is analyzed in multi-slice spiral CT. Unlike single-slice spiral CT, in which image quality deceases monotonically as the pitch increases, the sensitivity of raw data interpolation in multi-slice spiral CT increases in an alternating way as the pitch increases, suggesting that image quality does not decrease monotonically in this case. The most favorable pitch can be found from the sensitivity-pitch plot for any given set of multi-slice spiral CT parameters. An example for four-slice spiral CT is provided. The study on the pitch effect using the sensitivity analysis approach reveals the fundamental characteristics of raw data interpolation in multi-slice spiral CT, and gives insights into interaction between pitch and image quality. These results may be valuable for design of multi-slice spiral CT scanners and imaging protocol optimization in clinical applications.

  5. Imaging performance in differential phase contrast CT compared with the conventional CT-noise equivalent quanta NEQ(k)

    NASA Astrophysics Data System (ADS)

    Tang, Xiangyang; Yang, Yi; Tang, Shaojie

    2012-03-01

    The grating-based x-ray differential phase contrast (DPC) CT is emerging as a new technology with the potential for extensive preclinical and clinical applications. In general, the performance of an imaging system is jointly determined by its signal property (modulation transfer function-MTF(k)) and noise property (noise power spectrum-NPS(k)), which is characterized by its spectrum of noise equivalent quanta. As reported by us previously, owing to an adoption of the Hilbert filtering for image reconstruction in the fashion of filtered backprojection (FBP), the noise property of DPC-CT characterized by its NPS(k) differs drastically from that of the conventional attenuation-based CT (1/|k| trait vs. |k| trait). In this work, via system analysis, modeling and simulated phantom study, we initially investigate the signal property of DPC-CT characterized by its MTF(k) and compare it with that of the conventional CT. In addition, we investigate the DPC-CT's spectrum of noise equivalent quanta NEQ(k) - the most important figure of merit (FOM) in the assessment of an imaging system's performance - by taking the MTF(k) and NPS(k) jointly into account. Through such a thorough investigation into both the signal and noise properties, the imaging performance of DPC-CT and its potential over the conventional attenuation-based CT can be fully understood and appreciated.

  6. Combined hepatocellular and cholangiocarcinoma of the liver: sonography, CT, angiography, and iodized-oil CT with pathologic correlation.

    PubMed

    Choi, B I; Han, J K; Kim, Y I; Kim, H C; Park, J H; Kim, C W; Han, M C

    1994-01-01

    To evaluate the characteristics of combined hepatocellular and cholangiocarcinoma of the liver by imaging techniques, six patients (five male and one female), aged 46-60 years, with proved combined tumors were selected for this study from the review of 500 resected specimens of liver tumors. Images obtained from sonography, computed tomography (CT), angiography, and CT after intraarterial injection of iodized oil (iodized-oil CT) were retrospectively reviewed and correlated with the appearance of pathologic specimens. Sonographic findings were round or ovoid hypoechoic masses with central hyperechoic area (target appearance) in all patients. On CT scans, tumors were relatively well-defined low-and/or iso-attenuation masses in all patients. Angiography showed hypovascular masses in five patients. In one patient, the tumor appeared as a hypovascular mass with a central hypervascular area. On iodized-oil CT scans, all patients showed partial retention of iodized oil in tumors. Echogenicity in tumors at sonography or attenuation in tumors at CT could not be correlated with histologic difference in tumors at pathologic specimens. However, the hypervascular area at angiography and the compact retention areas of iodized oil at iodized-oil CT corresponded to portions of hepatocellular carcinoma within the combined tumor. On the basis of our results, imaging features, including target appearance at sonography, hypovascular mass with central hypervascular portions at angiography, and partial retention of iodized oil in tumors at iodized-oil CT, might be helpful in making accurate diagnosis of these rare tumors. PMID:8161902

  7. CT, MRI, PET, PET/CT, and ultrasound in the evaluation of obstetric and gynecologic patients.

    PubMed

    Gjelsteen, Andrew C; Ching, Brian H; Meyermann, Mark W; Prager, Douglas A; Murphy, Thomas F; Berkey, Bryan D; Mitchell, Lex A

    2008-04-01

    The role of imaging in obstetrics and gynecology has undergone a revolution over the past few decades. Well-established methods such as endovaginal ultrasound have had a central role in the evaluation of nongravid patients with pelvic pain, as well as in the workup for ectopic pregnancy and evaluation of adnexal masses. Additional tools include MRI in the evaluation of appendicitis and other potentially surgical conditions in pregnant patients and MRI and CT in the evaluation of surgical complications. Newer tools in the radiology armamentarium include PET scanning which, alongside MRI and CT, are often helpful in staging gynecologic malignancy. The role of imaging in the obstetric and gynecology patient will continue to change as new modalities and techniques are introduced. PMID:18381118

  8. Pulmonary nodule classification based on CT density distribution using 3D thoracic CT images

    NASA Astrophysics Data System (ADS)

    Kawata, Yoshiki; Niki, Noboru; Ohamatsu, Hironobu; Kusumoto, Masahiko; Kakinuma, Ryutaro; Mori, Kiyoshi; Yamada, Kozo; Nishiyama, Hiroyuki; Eguchi, Kenji; Kaneko, Masahiro; Moriyama, Noriyuki

    2004-04-01

    Computer-aided diagnosis (CAD) has been investigated to provide physicians with quantitative information, such as estimates of the malignant likelihood, to aid in the classification of abnormalities detected at screening of lung cancers. The purpose of this study is to develop a method for classifying nodule density patterns that provides information with respect to nodule statuses such as lesion stage. This method consists of three steps, nodule segmentation, histogram analysis of CT density inside nodule, and classifying nodules into five types based on histogram patterns. In this paper, we introduce a two-dimensional (2-D) joint histogram with respect to distance from nodule center and CT density inside nodule and explore numerical features with respect to shape and position of the joint histogram.

  9. CT and MR of pineal region tumors.

    PubMed

    Gouliamos, A D; Kalovidouris, A E; Kotoulas, G K; Athanasopoulou, A K; Kouvaris, J R; Trakadas, S J; Vlahos, L J; Papavasiliou, C G

    1994-01-01

    Magnetic Resonance (MR) imaging features of pineal region tumors were analyzed in 14 oncologic cases. The tumors were classified as germ-cell tumors, glial tumors, pineal parenchymal tumors, meningiomas, and cysts. They demonstrated different MR signal characteristics on precontrast scans and nodular or ring type enhancement with occasional central lucencies, except for benign cysts, which have not shown enhancement. MR images were useful in defining the relationship of the tumor to the posterior third ventricle, sylvian aqueduct, vein of Galen, and tentorium. Although CT can demonstrate in more evident fashion displacement of the original pineal calcification as well as tumor calcifications, MR imaging demonstrates different signal characteristics in germinomas and pineoblastomas which can be a useful adjunct in the evaluation and differential diagnosis of these tumors. PMID:8295504

  10. Windmill artifact in multislice helical CT

    NASA Astrophysics Data System (ADS)

    Silver, Michael D.; Taguchi, Katsuyuki; Hein, Ilmar A.; Chiang, BeShan; Kazama, Masahiro; Mori, Issei

    2003-05-01

    Multi-slice helical CT-systems suffer from windmill artifacts: black/white patterns that spin off of features with high longitudinal gradients. The number of black/white pairs matches the number of slices (detector rows) in the multi-slive detector. The period of spin is the same as the helical pitch. We investigate the cause of the pattern by following the traces of selected voxels through the multi-slive detector array as a function of view position. This forms an "extracted sinogram" which represents the data used to reconstruct the specific voxel. Now we can determine the cause of the artifact by correlating the windmill streak in the image with the extracted data. The investigation shows that inadequate sampling along the longitudinal direction causes the artifact.

  11. Robust registration of longitudinal spine CT.

    PubMed

    Glocker, Ben; Zikic, Darko; Haynor, David R

    2014-01-01

    Accurate and reliable registration of longitudinal spine images is essential for assessment of disease progression and surgical outcome. Implementing a fully automatic and robust registration for clinical use, however, is challenging since standard registration techniques often fail due to poor initial alignment. The main causes of registration failure are the small overlap between scans which focus on different parts of the spine and/or substantial change in shape (e.g. after correction of abnormal curvature) and appearance (e.g. due to surgical implants). To overcome these issues we propose a registration approach which incorporates estimates of vertebrae locations obtained from a learning-based classification method. These location priors are used to initialize the registration and to provide semantic information within the optimization process. Quantitative evaluation on a database of 93 patients with a total of 276 registrations on longitudinal spine CT demonstrate that our registration method significantly reduces the number of failure cases. PMID:25333125

  12. Tomosynthesis using high speed CT scanning system

    SciTech Connect

    Boyd, D.P.; Rutt, B.K.

    1988-04-05

    In a high-speed CT scanning system in which fan beams of radiation are generated by sweeping an electron beam along a target and collimated X-rays emitted by the target are received by an array of detectors after passing through a patient area between the target and the array of detectors, a method of obtaining a tomograph of a patient is described comprising the steps of sweeping the electron beam along the target, measuring radiation received at detector positions as the electron beam is swept along the target; moving the patient past the collimated X-rays, and combining measurements at the detector positions as correlated in time to positions of the patient and tomosynthesizing the tomograph from data for lines in the desired plane for the positions of the patient.

  13. Medipix3 CT for material sciences

    NASA Astrophysics Data System (ADS)

    Procz, S.; Wartig, K.-A.; Fauler, A.; Zwerger, A.; Luebke, J.; Ballabriga, R.; Blaj, G.; Campbell, M.; Mix, M.; Fiederle, M.

    2013-01-01

    Innovative detector systems for non-destructive material analysis and for medical diagnosis are an important development to improve the performance and the quality of examination methods. For a number of years now photon-counting X-ray detectors are being developed to process incoming X-ray photons as single events. These detectors facilitate a higher signal-to-noise ratio (SNR) than conventional, non-photon-counting, scintillator based detector systems, which detect X-ray photons indirectly through conversion into visible light. The Medipix is a pixelated photon counting semiconductor detector which features adjustable energy thresholds allowing energy selective, multispectral X-ray imaging. The Medipix chip is under continued development by the ``Medipix2 Collaboration'' and ``Medipix3 Collaboration'' at CERN [1]. The Medipix electronic offers 256 × 256 pixels with a pixel pitch of 55 × 55 μm2 and can be hybridized with different sensor materials like Si, CdTe or GaAs. The newest member of the Medipix family is the Medipix3 (ASIC in 0.13 μm CMOS technology) providing up to eight separate 12-bit counters per pixel. It offers a couple of different working modes [2], which are useful for X-ray imaging applications. A Medipix3 CT X-ray measuring station was built up for small animal X-ray imaging and non-destructive material analysis [3]. The combination of the low energy threshold ( ~ 4 keV) of the Medipix3 with its multispectral capability enables tomographic investigations on objects with low absorption contrast. The advantage of photon counting, multispectral detectors like Medipix3 for material sciences will be presented here as well as a comparison with a scintillator based CT.

  14. Performance evaluation of the CT component of the IRIS PET/CT preclinical tomograph

    NASA Astrophysics Data System (ADS)

    Panetta, Daniele; Belcari, Nicola; Tripodi, Maria; Burchielli, Silvia; Salvadori, Piero A.; Del Guerra, Alberto

    2016-01-01

    In this paper, we evaluate the physical performance of the CT component of the IRIS scanner, a novel combined PET/CT scanner for preclinical imaging. The performance assessment is based on phantom measurement for the determination of image quality parameters (spatial resolution, linearity, geometric accuracy, contrast to noise ratio) and reproducibility in dynamic (4D) imaging. The CTDI100 has been measured free in air with a pencil ionization chamber, and the animal dose was calculated using Monte Carlo derived conversion factors taken from the literature. The spatial resolution at the highest quality protocol was 6.9 lp/mm at 10% of the MTF, using the smallest reconstruction voxel size of 58.8 μm. The accuracy of the reconstruction voxel size was within 0.1%. The linearity of the CT numbers as a function of the concentration of iodine was very good, with R2>0.996 for all the tube voltages. The animal dose depended strongly on the scanning protocol, ranging from 158 mGy for the highest quality protocol (2 min, 80 kV) to about 12 mGy for the fastest protocol (7.3 s, 80 kV). In 4D dynamic modality, the maximum scanning rate reached was 3.1 frames per minute, using a short-scan protocol with 7.3 s of scan time per frame at the isotropic voxel size of 235 μm. The reproducibility of the system was high throughout the 10 frames acquired in dynamic modality, with a standard deviation of the CT values of all frames <8 HU and an average spatial reproducibility within 30% of the voxel size across all the field of view. Example images obtained during animal experiments are also shown.

  15. Deformable registration of CT and cone-beam CT by local CBCT intensity correction

    NASA Astrophysics Data System (ADS)

    Park, Seyoun; Plishker, William; Shekhar, Raj; Quon, Harry; Wong, John; Lee, Junghoon

    2015-03-01

    In this paper, we propose a method to accurately register CT to cone-beam CT (CBCT) by iteratively correcting local CBCT intensity. CBCT is a widely used intra-operative imaging modality in image-guided radiotherapy and surgery. A short scan followed by a filtered-backprojection is typically used for CBCT reconstruction. While data on the mid-plane (plane of source-detector rotation) is complete, off-mid-planes undergo different information deficiency and the computed reconstructions are approximate. This causes different reconstruction artifacts at off-mid-planes depending on slice locations, and therefore impedes accurate registration between CT and CBCT. To address this issue, we correct CBCT intensities by matching local intensity histograms slice by slice in conjunction with intensity-based deformable registration. This correction-registration step is repeated until the result image converges. We tested the proposed method on eight head-and-neck cancer cases and compared its performance with state-of-the-art registration methods, Bspline, demons, and optical flow, which are widely used for CT-CBCT registration. Normalized mutual-information (NMI), normalized cross-correlation (NCC), and structural similarity (SSIM) were computed as similarity measures for the performance evaluation. Our method produced overall NMI of 0.59, NCC of 0.96, and SSIM of 0.93, outperforming existing methods by 3.6%, 2.4%, and 2.8% in terms of NMI, NCC, and SSIM scores, respectively. Experimental results show that our method is more consistent and roust than existing algorithms, and also computationally efficient with faster convergence.

  16. CT Chest with IV Contrast Compared with CT Angiography after Blunt Trauma.

    PubMed

    Zaw, Andrea A; Stewart, Donovan; Murry, Jason S; Hoang, David M; Sun, Beatrice; Ashrafian, Sogol; Hotz, Heidi; Chung, Rex; Margulies, Daniel R; Ley, Eric J

    2016-01-01

    Blunt aortic injury (BAI) after chest trauma is a potentially lethal condition. Rapid diagnosis is important to appropriately treat patients. The purpose of this study was to compare CT with intravenous contrast (CTI) to CT with angiography (CTA) in the initial evaluation of blunt chest trauma patients. This was a retrospective review of all blunt trauma patients who received a CTI or CTA during the initial evaluation at an urban Level I trauma center from January 1, 2010 to December 31, 2013. Two-hundred and eighty-one trauma patients met inclusion criteria. Most, 167/281 (59%) received CTI and 114/281 (41%) received CTA. There were no differences between cohorts in age, gender, initial heart rate, systolic blood pressure, and Glasgow Coma Scale in emergency department. Mortality rates were similar for CTI and CTA (4% vs 8%, P = 0.20). CTI identified an injury in 54 per cent compared with 46 per cent in CTA (P = 0.05). Overall, 2 per cent of patients had BAI with similar rates in CTI and CTA (2% vs 2%, P = 0.80). BAI was not missed using either CTI or CTA. Trauma patients studied with CTI had similar diagnostic findings as CTA. CTI may be preferable to CTA during the initial assessment for possible BAI because of a single contrast injection for whole body CT. PMID:26802856

  17. Multiscale registration of planning CT and daily cone beam CT images for adaptive radiation therapy

    SciTech Connect

    Paquin, Dana; Levy, Doron; Xing Lei

    2009-01-15

    Adaptive radiation therapy (ART) is the incorporation of daily images in the radiotherapy treatment process so that the treatment plan can be evaluated and modified to maximize the amount of radiation dose to the tumor while minimizing the amount of radiation delivered to healthy tissue. Registration of planning images with daily images is thus an important component of ART. In this article, the authors report their research on multiscale registration of planning computed tomography (CT) images with daily cone beam CT (CBCT) images. The multiscale algorithm is based on the hierarchical multiscale image decomposition of E. Tadmor, S. Nezzar, and L. Vese [Multiscale Model. Simul. 2(4), pp. 554-579 (2004)]. Registration is achieved by decomposing the images to be registered into a series of scales using the (BV, L{sup 2}) decomposition and initially registering the coarsest scales of the image using a landmark-based registration algorithm. The resulting transformation is then used as a starting point to deformably register the next coarse scales with one another. This procedure is iterated at each stage using the transformation computed by the previous scale registration as the starting point for the current registration. The authors present the results of studies of rectum, head-neck, and prostate CT-CBCT registration, and validate their registration method quantitatively using synthetic results in which the exact transformations our known, and qualitatively using clinical deformations in which the exact results are not known.

  18. CT Chest with IV Contrast Compared with CT Angiography after Blunt Trauma.

    PubMed

    Zaw, Andrea A; Stewart, Donovan; Murry, Jason S; Hoang, David M; Sun, Beatrice; Ashrafian, Sogol; Hotz, Heidi; Chung, Rex; Margulies, Daniel R; Ley, Eric J

    2015-10-01

    Blunt aortic injury (BAI) after chest trauma is a potentially lethal condition that requires rapid diagnosis for appropriate treatment. We compared CT with IV contrast (CTI) with CT with angiography (CTA) during the initial phase of care at an urban Level I trauma center from January 1, 2010 to December 31, 2013. Overall, 281 patients met inclusion criteria with 167 (59%) CTI and 114 (41%) CTA. There were no differences between cohorts in age, gender, initial heart rate, systolic blood pressure, and Glasgow Coma Scale. Mortality rates were similar for CTI and CTA (4% vs 8%, P = 0.20). CTI identified any chest injury in 54 per cent of patients compared with 46 per cent with CTA (P = 0.05). The rate of BAI was similar with CTI and CTA (2% vs 2%, P = 0.80), and neither modality was falsely negative. We conclude that CTI and CTA are similar at evaluating trauma patients for BAI, although CTI may be preferable during the initial assessment phase because the contrast injection may be combined with abdominal scanning and image time is reduced when whole-body CT is required. PMID:26463312

  19. Organ doses to adult patients for chest CT

    SciTech Connect

    Huda, Walter; Sterzik, Alexander; Tipnis, Sameer; Schoepf, U. Joseph

    2010-02-15

    Purpose: The goal of this study was to estimate organ doses for chest CT examinations using volume computed tomography dose index (CTDI{sub vol}) data as well as accounting for patient weight. Methods: A CT dosimetry spreadsheet (ImPACT CT patient dosimetry calculator) was used to compute organ doses for a 70 kg patient undergoing chest CT examinations, as well as volume computed tomography dose index (CTDI{sub vol}) in a body CT dosimetry phantom at the same CT technique factors. Ratios of organ dose to CTDI{sub vol} (f{sub organ}) were generated as a function of anatomical location in the chest for the breasts, lungs, stomach, red bone marrow, liver, thyroid, liver, and thymus. Values of f{sub organ} were obtained for x-ray tube voltages ranging from 80 to 140 kV for 1, 4, 16, and 64 slice CT scanners from two vendors. For constant CT techniques, we computed ratios of dose in water phantoms of differing diameter. By modeling patients of different weights as equivalent water cylinders of different diameters, we generated factors that permit the estimation of the organ doses in patients weighing between 50 and 100 kg who undergo chest CT examinations relative to the corresponding organ doses received by a 70 kg adult. Results: For a 32 cm long CT scan encompassing the complete lungs, values of f{sub organ} ranged from 1.7 (thymus) to 0.3 (stomach). Organs that are directly in the x-ray beam, and are completely irradiated, generally had f{sub organ} values well above 1 (i.e., breast, lung, heart, and thymus). Organs that are not completely irradiated in a total chest CT scan generally had f{sub organ} values that are less than 1 (e.g., red bone marrow, liver, and stomach). Increasing the x-ray tube voltage from 80 to 140 kV resulted in modest increases in f{sub organ} for the heart (9%) and thymus (8%), but resulted in larger increases for the breast (19%) and red bone marrow (21%). Adult patient chests have been modeled by water cylinders with diameters between

  20. CT and Ultrasound Guided Stereotactic High Intensity Focused Ultrasound (HIFU)

    SciTech Connect

    Wood, Bradford J.; Frenkel, V.; Viswanathan, A.; Dromi, S.; Oh, K.; Kam, A.; Li, K. C. P.; Yanof, J.; Bauer, C.; Kruecker, J.; Seip, R.

    2006-05-08

    To demonstrate the feasibility of CT and B-mode Ultrasound (US) targeted HIFU, a prototype coaxial focused ultrasound transducer was registered and integrated to a CT scanner. CT and diagnostic ultrasound were used for HIFU targeting and monitoring, with the goals of both thermal ablation and non-thermal enhanced drug delivery. A 1 megahertz coaxial ultrasound transducer was custom fabricated and attached to a passive position-sensing arm and an active six degree-of-freedom robotic arm via a CT stereotactic frame. The outer therapeutic transducer with a 10 cm fixed focal zone was coaxially mounted to an inner diagnostic US transducer (2-4 megahertz, Philips Medical Systems). This coaxial US transducer was connected to a modified commercial focused ultrasound generator (Focus Surgery, Indianapolis, IN) with a maximum total acoustic power of 100 watts. This pre-clinical paradigm was tested for ability to heat tissue in phantoms with monitoring and navigation from CT and live US. The feasibility of navigation via image fusion of CT with other modalities such as PET and MRI was demonstrated. Heated water phantoms were tested for correlation between CT numbers and temperature (for ablation monitoring). The prototype transducer and integrated CT/US imaging system enabled simultaneous multimodality imaging and therapy. Pre-clinical phantom models validated the treatment paradigm and demonstrated integrated multimodality guidance and treatment monitoring. Temperature changes during phantom cooling corresponded to CT number changes. Contrast enhanced or non-enhanced CT numbers may potentially be used to monitor thermal ablation with HIFU. Integrated CT, diagnostic US, and therapeutic focused ultrasound bridges a gap between diagnosis and therapy. Preliminary results show that the multimodality system may represent a relatively inexpensive, accessible, and simple method of both targeting and monitoring HIFU effects. Small animal pre-clinical models may be translated to large

  1. CT and Ultrasound Guided Stereotactic High Intensity Focused Ultrasound (HIFU)

    NASA Astrophysics Data System (ADS)

    Wood, Bradford J.; Yanof, J.; Frenkel, V.; Viswanathan, A.; Dromi, S.; Oh, K.; Kruecker, J.; Bauer, C.; Seip, R.; Kam, A.; Li, K. C. P.

    2006-05-01

    To demonstrate the feasibility of CT and B-mode Ultrasound (US) targeted HIFU, a prototype coaxial focused ultrasound transducer was registered and integrated to a CT scanner. CT and diagnostic ultrasound were used for HIFU targeting and monitoring, with the goals of both thermal ablation and non-thermal enhanced drug delivery. A 1 megahertz coaxial ultrasound transducer was custom fabricated and attached to a passive position-sensing arm and an active six degree-of-freedom robotic arm via a CT stereotactic frame. The outer therapeutic transducer with a 10 cm fixed focal zone was coaxially mounted to an inner diagnostic US transducer (2-4 megahertz, Philips Medical Systems). This coaxial US transducer was connected to a modified commercial focused ultrasound generator (Focus Surgery, Indianapolis, IN) with a maximum total acoustic power of 100 watts. This pre-clinical paradigm was tested for ability to heat tissue in phantoms with monitoring and navigation from CT and live US. The feasibility of navigation via image fusion of CT with other modalities such as PET and MRI was demonstrated. Heated water phantoms were tested for correlation between CT numbers and temperature (for ablation monitoring). The prototype transducer and integrated CT/US imaging system enabled simultaneous multimodality imaging and therapy. Pre-clinical phantom models validated the treatment paradigm and demonstrated integrated multimodality guidance and treatment monitoring. Temperature changes during phantom cooling corresponded to CT number changes. Contrast enhanced or non-enhanced CT numbers may potentially be used to monitor thermal ablation with HIFU. Integrated CT, diagnostic US, and therapeutic focused ultrasound bridges a gap between diagnosis and therapy. Preliminary results show that the multimodality system may represent a relatively inexpensive, accessible, and simple method of both targeting and monitoring HIFU effects. Small animal pre-clinical models may be translated to large

  2. Clinical application of CT and CT-guided percutaneous transthoracic needle biopsy in patients with indeterminate pulmonary nodules*

    PubMed Central

    Cardoso, Luciana Vargas; Souza, Arthur Soares

    2014-01-01

    OBJECTIVE: To investigate the clinical application of CT and CT-guided percutaneous transthoracic needle biopsy (CT-PTNB) in patients with indeterminate pulmonary nodules (IPNs). METHODS: We retrospectively studied 113 patients with PNs undergoing CT and CT-PTNB. Variables such as gender, age at diagnosis, smoking status, CT findings, and CT-PTNB techniques were analyzed. Data analysis was performed with the Student's t-test for independent samples the chi-square test, and normal approximation test for comparison of two proportions. RESULTS: Of the 113 patients studied, 68 (60.2%) were male and 78 (69%) were smokers. The diameter of malignant lesions ranged from 2.6 cm to 10.0 cm. Most of the IPNs (85%) were located in the peripheral region. The biopsied IPNs were found to be malignant in 88 patients (77.8%) and benign in 25 (22.2%). Adenocarcinoma was the most common malignant tumor, affecting older patients. The IPN diameter was significantly greater in patients with malignant PNs than in those with benign IPNs (p < 0.001). Having regular contour correlated significantly with an IPN being benign (p = 0.022), whereas spiculated IPNs and bosselated IPNs were more often malignant (in 50.7% and 28.7%, respectively). Homogeneous attenuation and necrosis were more common in patients with malignant lesions (51.9% and 26.9%, respectively) CONCLUSIONS: In our sample, CT and CT-PTNB were useful in distinguishing between malignant and benign IPNs. Advanced age and smoking were significantly associated with malignancy. Certain CT findings related to IPNs (larger diameter, spiculated borders, homogeneous attenuation, and necrosis) were associated with malignancy. PMID:25210960

  3. Evaluation of pulmonary nodules and lung cancer with one-inch crystal gamma coincidence positron emission tomography/CT versus dedicated positron emission tomography/CT.

    PubMed

    Moodie, K; Cherk, M H; Lau, E; Turlakow, A; Skinner, S; Hicks, R J; Kelly, M J; Kalff, V

    2009-02-01

    Dedicated positron emission tomography (PET)/CT scanners using BGO and related detectors (d-PET) have become standard imaging instruments in many malignancies. Hybrid gamma camera systems using NaI detectors in coincidence mode (g-PET) have been compared to d-PET but reported usefulness has been variable when gamma cameras with half-inch to three-fourth-inch thick crystals have been used without CT. Our aim was to compare g-PET with a 1-in.-thick crystal and inbuilt CT for lesion localization and attenuation correction (g-PET/CT) and d-PET/CT in patients presenting with potential and confirmed lung malignancies. One hour after (18)F-fluorodeoxyglucose (FDG), patients underwent BGO d-PET/CT from jaw to proximal thigh. This was followed by one to two bed position g-PET/CT 194 +/- 27 min after FDG. Each study pair was independently analysed with concurrent CT. d-PET/CT was interpreted by a radiologist experienced in both PET and CT, and g-PET/CT by consensus reading of an experienced PET physician and an experienced CT radiologist. A TNM score was assigned and studies were then unblinded and compared. Fifty-seven patients underwent 58 scan pairs over 2 years. Eighty-nine per cent concordance was shown between g-PET/CT and d-PET/CT for the assessment of intrapulmonary lesions, with 100% concordance for intrapulmonary lesions >10 mm (36 of 36). Eighty-eight per cent (51 of 58) concordance was shown between g-PET/CT and d-PET/CT for TNM staging. Coincidence imaging using an optimized dual-head 1-in.-thick crystal gamma camera with inbuilt CT compares reasonably well with dedicated PET/CT for evaluation of indeterminate pulmonary lesions and staging of pulmonary malignancies and may be of some value when d-PET/CT is not readily available. PMID:19453526

  4. Recent Advances in Cardiac Computed Tomography: Dual Energy, Spectral and Molecular CT Imaging

    PubMed Central

    Danad, Ibrahim; Fayad, Zahi A.; Willemink, Martin J.; Min, James K.

    2015-01-01

    Computed tomography (CT) evolved into a powerful diagnostic tool and it is impossible to imagine current clinical practice without CT imaging. Due to its widespread availability, ease of clinical application, superb sensitivity for detection of CAD, and non-invasive nature, CT has become a valuable tool within the armamentarium of the cardiologist. In the last few years, numerous technological advances in CT have occurred—including dual energy CT (DECT), spectral CT and CT-based molecular imaging. By harnessing the advances in technology, cardiac CT has advanced beyond the mere evaluation of coronary stenosis to an imaging modality tool that permits accurate plaque characterization, assessment of myocardial perfusion and even probing of molecular processes that are involved in coronary atherosclerosis. Novel innovations in CT contrast agents and pre-clinical spectral CT devices have paved the way for CT-based molecular imaging. PMID:26068288

  5. New Applications of Cardiac Computed Tomography: Dual-Energy, Spectral, and Molecular CT Imaging.

    PubMed

    Danad, Ibrahim; Fayad, Zahi A; Willemink, Martin J; Min, James K

    2015-06-01

    Computed tomography (CT) has evolved into a powerful diagnostic tool, and it is impossible to imagine current clinical practice without CT imaging. Because of its widespread availability, ease of clinical application, superb sensitivity for the detection of coronary artery disease, and noninvasive nature, CT has become a valuable tool within the armamentarium of cardiologists. In the past few years, numerous technological advances in CT have occurred, including dual-energy CT, spectral CT, and CT-based molecular imaging. By harnessing the advances in technology, cardiac CT has advanced beyond the mere evaluation of coronary stenosis to an imaging tool that permits accurate plaque characterization, assessment of myocardial perfusion, and even probing of molecular processes that are involved in coronary atherosclerosis. Novel innovations in CT contrast agents and pre-clinical spectral CT devices have paved the way for CT-based molecular imaging. PMID:26068288

  6. The need for skull radiography in patients presenting for CT

    SciTech Connect

    Tress, B.M.

    1983-01-01

    One thousand patients had both CT of the head and a conventional skull series of radiographs. Radiographic findings were abnormal in 250 patients (25%), but only 64 patients (6.4%) had diagnostically significant abnormalities at radiography that were not detected by CT. If the 163 patients who presented after acute trauma were excluded from the series, only 39 (4.7%) of the remaining patients had radiographically significant abnormal findings that were not seen at CT, and only two (0.2%) of these abnormalities could not be diagnosed by a lateral skull radiograph alone. In only five patients (0.5%) was the management actively changed because an abnormaltiy that was detected at skull radiography was not detected at CT. Thus, in nontrauma patients who have stroke, epilepsy, dementia, or non-specific symptoms without focal signs, or have recently undergone craniotomy, and who have been referred for CT, skull radiographs are not justified. In the patient with a history and findings that are strongly suggestive of a pathological disorder anywhere other than in the sella turcica, cerebello-pontine angle, and paranasal sinuses, only the lateral skull radiograph should be obtained after CT, and only if CT is equivocal.

  7. The effects of respiration motion in PET/CT studies

    NASA Astrophysics Data System (ADS)

    Wan, Lu; Wu, Zhijian; Zhou, Fengyin; Ye, Sheng; Zeng, Shaoqun; Kao, Chien-Min; Chen, Chin-Tu; Zhang, Yongxue; Xie, Qingguo

    2008-03-01

    In recent years, the clinical status of positron emission tomography(PET)/computed tomography(CT) in achieving more accurate staging of lung cancer has been established and the technology has been enthusiastically accepted by the medical community. However, its capability in chest imaging is still limited by several physical factors. As a result of typical PET/CT imaging protocol, respiration-averaged PET data and free of respiration-averaged CT data are collected in a PET/CT scanning. In this work, we investigate the effects of respiration motion. We employ mathematical and Monte-Carlo simulations for generating PET/CT data. We scale a Zubal phantom to generate 30 phantoms having various sizes in order to represent different torso anatomic states during respiration. Images reconstructed from selected scaling PET data using the respective scaling PET attenuation maps serve as baseline results. PET/CT imaging protocol is simulated by reconstruction from respiration-averaged PET data with the selected PET attenuation maps. We also reconstruct PET images from respiratory-averaged PET data with respiration-averaged PET attenuation maps, which simulates conventional PET imaging protocol. We will compare the resulting images reconstructed from the above-mentioned approaches to evaluate the effects of respiration motion in PET/CT.

  8. Reconstruction algorithm improving the spatial resolution of Micro-CT

    NASA Astrophysics Data System (ADS)

    Fu, Jian; Wei, Dongbo; Li, Bing; Zhang, Lei

    2008-03-01

    X-ray Micro computed tomography (Micro-CT) enables nondestructive visualization of the internal structure of objects with high-resolution images and plays an important role for industrial nondestructive testing, material evaluation and medical researches. Because the micro focus is much smaller than the ordinary focus, the geometry un-sharpness of Micro-CT projection is several decuples less than that of ordinary CT systems. So the scan conditions with high geometry magnification can be adopted to acquire the projection data with high sampling frequency. Based on this feature, a new filter back projection reconstruction algorithm is researched to improve the spatial resolution of Micro-CT. This algorithm permits the reconstruction center at any point on the line connecting the focus and the rotation center. It can reconstruct CT images with different geometry magnification by adjusting the position of the reconstruction center. So it can make the best of the above feature to improve the spatial resolution of Micro-CT. The computer simulation and the CT experiment of a special spatial resolution phantom are executed to check the validity of this method. The results demonstrate the effect of the new algorithm. Analysis shows that the spatial resolution can be improved 50%.

  9. Current status of developments and applications of micro-CT.

    PubMed

    Ritman, Erik L

    2011-08-15

    Use of microscopic computed-tomography (micro-CT) scanning continues to grow in biomedical research. Laboratory-based micro-CT scanners, laboratory-based nano-CT scanners, and integrated micro-CT/SPECT and micro-CT/PET scanners are now manufactured for "turn-key" operation by a number of commercial vendors. In recent years a number of technical developments in X-ray sources and X-ray imaging arrays have broadened the utility of micro-CT. Of particular interest are photon-counting and energy-resolving detector arrays. These are being explored to maximize micro-CT image grayscale dynamic range and to further increase image contrast by utilizing the unique spectral attenuation characteristics of individual chemical elements. X-ray phase-shift images may increase contrast resolution and reduce radiation exposure. Although radiation exposure is becoming a concern with the drive for increased spatial and temporal resolution, especially for longitudinal studies, gated scans and limited scan-data-set reconstruction algorithms show great potential for keeping radiation exposure to a minimum. PMID:21756145

  10. Development and evaluation of a novel designed breast CT system

    NASA Astrophysics Data System (ADS)

    Braun, Claudia; Schlattl, Helmut; Tischenko, Oleg; Dietrich, Olaf; Hoeschen, Christoph

    2014-03-01

    The performance of a novel designed x-ray CT scanning geometry is investigated. Composed of a specially designed tungsten collimation mask and a high resolution flat panel detector, this scanning geometry provides high efficient data acquisition allowing dose reduction potentially up to 50%. In recent years a special type of scanning geometry has been proposed. A first prototype of this geometry called CTDOR( CT with Dual Optimal Reading) has already been built. Despite many drawbacks, resulting images have shown promising potential of dual reading. The approach of gaining two subsets of data has anew been picked up and come to terms with a novel designed CT scanner for breast imaging. The main idea consists of collimating the X-ray beam through a specially designed shielding mask thereby reducing radiation dose without compromising image quality. This is achieved by hexagonally sampled Radon transform and image reconstruction with the especially suitable OPED (orthogonal polynomial expansion on disk) algorithm. This work now presents the development and evaluation of the novel designed breast CT system. Therefore simulated phantom data were obtained to test the performance of the scanning device and compared to a standard 3rd generation scanner. Retaining advantages such as scatter-correction potential and 3D-capability, the proposed CT system yields high resolution images for breast diagnostics in low energy ranges. Assuming similar sample size, it is expected that the novel designed breast CT system in conjunction with OPED outperforms the standard 3rd generation CT system combined with FBP (filtered back projection).

  11. Dual-Energy CT: Spectrum of Thoracic Abnormalities.

    PubMed

    Otrakji, Alexi; Digumarthy, Subba R; Lo Gullo, Roberto; Flores, Efren J; Shepard, Jo-Anne O; Kalra, Mannudeep K

    2016-01-01

    Recent studies have demonstrated that dual-energy computed tomography (CT) can provide useful information in several chest-related clinical indications. Compared with single-energy CT, dual-energy CT of the chest is feasible with the use of a radiation-dose-neutral scanning protocol. This article highlights the different types of images that can be generated by using dual-energy CT protocols such as virtual monochromatic, virtual unenhanced (ie, water), and pulmonary blood volume (ie, iodine) images. The physical basis of dual-energy CT and material decomposition are explained. The advantages of the use of virtual low-monochromatic images include reduced volume of intravenous contrast material and improved contrast resolution of images. The use of virtual high-monochromatic images can reduce beam hardening and contrast streak artifacts. The pulmonary blood volume images can help differentiate various parenchymal abnormalities, such as infarcts, atelectasis, and pneumonias, as well as airway abnormalities. The pulmonary blood volume images allow quantitative and qualitative assessment of iodine distribution. The estimation of iodine concentration (quantitative assessment) provides objective analysis of enhancement. The advantages of virtual unenhanced images include differentiation of calcifications, talc, and enhanced thoracic structures. Dual-energy CT has applications in oncologic imaging, including diagnosis of thoracic masses, treatment planning, and assessment of response to treatment. Understanding the concept of dual-energy CT and its clinical application in the chest are the goals of this article. PMID:26761530

  12. PET/CT imaging in lung cancer: indications and findings*

    PubMed Central

    Hochhegger, Bruno; Alves, Giordano Rafael Tronco; Irion, Klaus Loureiro; Fritscher, Carlos Cezar; Fritscher, Leandro Genehr; Concatto, Natália Henz; Marchiori, Edson

    2015-01-01

    The use of PET/CT imaging in the work-up and management of patients with lung cancer has greatly increased in recent decades. The ability to combine functional and anatomical information has equipped PET/CT to look into various aspects of lung cancer, allowing more precise disease staging and providing useful data during the characterization of indeterminate pulmonary nodules. In addition, the accuracy of PET/CT has been shown to be greater than is that of conventional modalities in some scenarios, making PET/CT a valuable noninvasive method for the investigation of lung cancer. However, the interpretation of PET/CT findings presents numerous pitfalls and potential confounders. Therefore, it is imperative for pulmonologists and radiologists to familiarize themselves with the most relevant indications for and limitations of PET/CT, seeking to protect their patients from unnecessary radiation exposure and inappropriate treatment. This review article aimed to summarize the basic principles, indications, cancer staging considerations, and future applications related to the use of PET/CT in lung cancer. PMID:26176525

  13. PET/CT AND RADIOIMMUNOTHERAPY OF PROSTATE CANCER

    PubMed Central

    Bouchelouche, Kirsten; Capala, Jacek; Oehr, Peter

    2009-01-01

    Purpose of review Traditional morphologically based imaging modalities are now being complemented by positron emission tomography (PET)/computerized tomography (CT) in prostate cancer. Metastatic prostate cancer is an attractive target for radioimmunotherapy (RIT) since no effective therapies are available. This review highlights the most important achievements within the last year in PET/CT and RIT of prostate cancer. Recent findings Conflicting results exist on the use of choline for detection of malignant disease in the prostate gland. The role of PET/CT in N-staging remains to be elucidated further. However, 18F-choline and 11C-choline PET/CT have been demonstrated to be useful for detection of recurrence. 18F-choline and 18F-fluoride PET/CT are useful for detection of bone metastases. Prostate tumor antigens may be used as targets for RIT. Prostate specific membrane antigen (PSMA) is currently under focus of a number of diagnostic and therapeutic strategies. J591, a monoclonal antibody, that targets the extracellular domain of PSMA, shows promising results. HER2 receptors may also have a potential as target for PET/CT imaging and RIT of advanced prostate cancer. Summary PET/CT in prostate cancer has proven to play a significant role, in particular for detection of prostate cancer recurrence and bone metastases. Radioimmunotherapy of metastatic prostate cancer warrant further investigations. PMID:19535981

  14. Development and quality characterization of a novel CT system

    NASA Astrophysics Data System (ADS)

    Schegerer, Alexander A.; Lingenheil, Martin; Klaften, Matthias; Förster, Thomas; Hrabé de Angelis, Martin; Hoeschen, Christoph

    2010-04-01

    Novel geometrical designs of computed tomography (CT) scanners in combination with novel image reconstruction algorithms promise to reduce ionizing radiation exposure to the patient in CT scans. While the sampling density of the Field Of View (FOV) is retained, the image quality can even be increased in contrast to conventional CT scanners. In this study, we present first images obtained with a novel CT scanner that we developed in our working group. In this open CT system with irradiation within a fan beam, parallel Radon data are directly obtained for image reconstruction using the OPED (Orthogonal Polynomial Expansion on the Disk) algorithm. This algorithm uses Radon data directly, i.e., without any further data processing such as rebinning and interpolation. We experimentally test theoretical predictions for this system by quantifying image quality parameters in comparison with corresponding parameters that are derived from the images of a conventional scanner of the 3rd generation. The modulation transfer function (MTF) and noise power spectrum (NPS) are determined using a test phantom. The novel CT system quantitatively shows the same noise property as the conventional scanner. The resolution that is reached in the center of a reconstructed image is nearly identical for both scanner types. But we found that the resolution that is achieved in the novel CT system does not depend on the image position while the MTF of the conventional scanner decreases for radially outer regions of the image.

  15. The Need for a Global Language - SNOMED CT Introduction.

    PubMed

    Millar, Jane

    2016-01-01

    SNOMED CT is the most comprehensive, multilingual clinical healthcare terminology in the world. It is a resource with comprehensive, scientifically validated clinical content. SNOMED CT enables consistent, processable representation of clinical content in electronic health records. When implemented in software applicationsSNOMED CT can be used to represent clinically relevant information consistently, reliabl comprehensively as an integral part of producing electronic health information. SNOMED CT supports the development of comprehensive high-quality clinical content in health records. It provides a standardized way to represent clinical phrases captured by the healthcare professional and enables automatic interpretation of these. SNOMED CT is a clinically validated, semantically rich, controlled vocabulary that facilitates evolutionary growth in expressivity to meet emerging requirements. SNOMED CT based clinical information benefits individual patients and clinicians as well as populations and it supports evidence based care. The use of an Electronic Health Record (EHR) improves communication and increases the availability of relevant information. IHTSDO works with other standards oganisations to ensure interoperability and a key area has been the work with ICN to enable the use of ICNP and SNOMED CT by the nursing profession internationally. PMID:27332304

  16. A review of CT-P13: an infliximab biosimilar.

    PubMed

    McKeage, Kate

    2014-06-01

    CT-P13 (Remsima™; Inflectra™), a biosimilar of reference infliximab (Remicade(®)), is approved by the European Medicines Agency for use in all indications for which reference infliximab is approved, including rheumatoid arthritis, ankylosing spondylitis, Crohn's disease, ulcerative colitis, psoriatic arthritis and psoriasis. Infliximab is a chimeric human-murine monoclonal antibody against the proinflammatory cytokine tumour necrosis factor-α. The CT-P13 infliximab formulation is identical to that of reference infliximab and it has similar physiochemical characteristics. The approval of CT-P13 was based on the results of a rigorous, comparability exercise. This article reviews the results of that exercise, focusing on the clinical evaluation programme. In two well-designed clinical trials, CT-P13 was equivalent to reference infliximab in terms of pharmacokinetic properties in patients with ankylosing spondylitis and in terms of efficacy in patients with rheumatoid arthritis. In both studies, CT-P13 was generally well tolerated with a similar tolerability profile to that of reference infliximab. Immunogenicity evaluations demonstrated that the proportion of patients developing anti-drug antibodies was similar with each agent. Preliminary data from trial extensions demonstrated that in patients who switched from reference infliximab to CT-P13, efficacy was sustained and similar to those who were treated continuously with CT-P13. As with all biosimilar and generic agents, CT-P13 has the potential to reduce treatment costs compared with those of reference infliximab, and modelled analyses predict significant cost savings compared with reference infliximab. In conclusion, CT-P13 is an infliximab biosimilar that provides a useful alternative to reference infliximab in patients requiring infliximab therapy. PMID:24723086

  17. CT Perfusion of the Liver: Principles and Applications in Oncology

    PubMed Central

    Kim, Se Hyung; Kamaya, Aya

    2014-01-01

    With the introduction of molecularly targeted chemotherapeutics, there is an increasing need for defining new response criteria for therapeutic success because use of morphologic imaging alone may not fully assess tumor response. Computed tomographic (CT) perfusion imaging of the liver provides functional information about the microcirculation of normal parenchyma and focal liver lesions and is a promising technique for assessing the efficacy of various anticancer treatments. CT perfusion also shows promising results for diagnosing primary or metastatic tumors, for predicting early response to anticancer treatments, and for monitoring tumor recurrence after therapy. Many of the limitations of early CT perfusion studies performed in the liver, such as limited coverage, motion artifacts, and high radiation dose of CT, are being addressed by recent technical advances. These include a wide area detector with or without volumetric spiral or shuttle modes, motion correction algorithms, and new CT reconstruction technologies such as iterative algorithms. Although several issues related to perfusion imaging—such as paucity of large multicenter trials, limited accessibility of perfusion software, and lack of standardization in methods—remain unsolved, CT perfusion has now reached technical maturity, allowing for its use in assessing tumor vascularity in larger-scale prospective clinical trials. In this review, basic principles, current acquisition protocols, and pharmacokinetic models used for CT perfusion imaging of the liver are described. Various oncologic applications of CT perfusion of the liver are discussed and current challenges, as well as possible solutions, for CT perfusion are presented. © RSNA, 2014 Online supplemental material is available for this article. PMID:25058132

  18. Spectra of clinical CT scanners using a portable Compton spectrometer

    SciTech Connect

    Duisterwinkel, H. A.; Abbema, J. K. van; Kawachimaru, R.; Paganini, L.; Graaf, E. R. van der; Brandenburg, S.; Goethem, M. J. van

    2015-04-15

    Purpose: Spectral information of the output of x-ray tubes in (dual source) computer tomography (CT) scanners can be used to improve the conversion of CT numbers to proton stopping power and can be used to advantage in CT scanner quality assurance. The purpose of this study is to design, validate, and apply a compact portable Compton spectrometer that was constructed to accurately measure x-ray spectra of CT scanners. Methods: In the design of the Compton spectrometer, the shielding materials were carefully chosen and positioned to reduce background by x-ray fluorescence from the materials used. The spectrum of Compton scattered x-rays alters from the original source spectrum due to various physical processes. Reconstruction of the original x-ray spectrum from the Compton scattered spectrum is based on Monte Carlo simulations of the processes involved. This reconstruction is validated by comparing directly and indirectly measured spectra of a mobile x-ray tube. The Compton spectrometer is assessed in a clinical setting by measuring x-ray spectra at various tube voltages of three different medical CT scanner x-ray tubes. Results: The directly and indirectly measured spectra are in good agreement (their ratio being 0.99) thereby validating the reconstruction method. The measured spectra of the medical CT scanners are consistent with theoretical spectra and spectra obtained from the x-ray tube manufacturer. Conclusions: A Compton spectrometer has been successfully designed, constructed, validated, and applied in the measurement of x-ray spectra of CT scanners. These measurements show that our compact Compton spectrometer can be rapidly set-up using the alignment lasers of the CT scanner, thereby enabling its use in commissioning, troubleshooting, and, e.g., annual performance check-ups of CT scanners.

  19. Mechanisms Directing the Nuclear Localization of the CtBP Family Proteins

    PubMed Central

    Verger, Alexis; Quinlan, Kate G. R.; Crofts, Linda A.; Spanò, Stefania; Corda, Daniela; Kable, Eleanor P. W.; Braet, Filip; Crossley, Merlin

    2006-01-01

    The C-terminal binding protein (CtBP) family includes four proteins (CtBP1 [CtBP1-L], CtBP3/BARS [CtBP1-S], CtBP2, and RIBEYE) which are implicated both in transcriptional repression and in intracellular trafficking. However, the precise mechanisms by which different CtBP proteins are targeted to different subcellular regions remains unknown. Here, we report that the nuclear import of the various CtBP proteins and splice isoforms is differentially regulated. We show that CtBP2 contains a unique nuclear localization signal (NLS) located within its N-terminal region, which contributes to its nuclear accumulation. Using heterokaryon assays, we show that CtBP2 is capable of shuttling between the nucleus and cytoplasm of the cell. Moreover, CtBP2 can heterodimerize with CtBP1-L and CtBP1-S and direct them to the nucleus. This effect strongly depends on the CtBP2 NLS. PXDLS motif-containing transcription factors, such as BKLF, that bind CtBP proteins can also direct them to the nucleus. We also report the identification of a splice isoform of CtBP2, CtBP2-S, that lacks the N-terminal NLS and localizes to the cytoplasm. Finally, we show that mutation of the CtBP NADH binding site impairs the ability of the proteins to dimerize and to associate with BKLF. This reduces the nuclear accumulation of CtBP1. Our results suggest a model in which the nuclear localization of CtBP proteins is influenced by the CtBP2 NLS, by binding to PXDLS motif partner proteins, and through the effect of NADH on CtBP dimerization. PMID:16782877

  20. Could contrast-enhanced CT detect STEMI prior to electrocardiogram?

    PubMed

    Sabbagh, Chadi; Rahi, Mayda; Baz, Maria; Haddad, Fadi; Helwe, Omar; Aoun, Noel; Ibrahim, Tony; Abdo, Lynn

    2015-01-01

    We present here a case in which contrast-enhanced computed tomography (CT) was the first diagnostic tool to detect myocardial hypoperfusion in a patient with atypical symptoms and normal electrocardiogram (ECG) on admission. An ST-segment elevation was detected thereafter on a second ECG realized several minutes after CT with raised troponin levels. Percutaneous coronary intervention was performed after failure of thrombolysis and confirmed occlusion of the left anterior descending artery. Further studies are needed to evaluate the role of high-resolution contrast-enhanced CT with or without coronary angiography in the workup of suspected myocardial infarction in the setting of a normal ECG. PMID:25085282

  1. Nonodontogenic mandibular lesions: differentiation based on CT attenuation

    PubMed Central

    Özgür, Anıl; Kara, Engin; Arpacı, Rabia; Arpacı, Taner; Esen, Kaan; Kara, Taylan; Duce, Meltem Nass; Apaydın, Feramuz Demir

    2014-01-01

    Mandibular lesions are classified as odontogenic and nonodontogenic based on the cell of origin. Odontogenic lesions are frequently encountered at head and neck imaging. However, several nonodontogenic pathologies may also involve mandible and present further diagnostic dilemma. Awareness of the imaging features of nonodontogenic lesions is crucial in order to guide clinicians in proper patient management. Computed tomography (CT) may provide key information to narrow diagnostic considerations. Nonodontogenic mandibular lesions may have lytic, sclerotic, ground-glass, or mixed lytic and sclerotic appearances on CT. In this article, our aim is to present various nonodontogenic lesions of the mandible by categorizing them according to their attenuations on CT. PMID:25297390

  2. Invisible fat on CT: making it visible by MRI

    PubMed Central

    Ünal, Emre; Karaosmanoğlu, Ali Devrim; Akata, Deniz; Özmen, Mustafa Nasuh; Karçaaltıncaba, Muşturay

    2016-01-01

    Presence of fat in a lesion significantly narrows the differential diagnosis. Small quantities of macroscopic fat and intracellular fat are invisible on computed tomography (CT) and ultrasonography. Magnetic resonance imaging (MRI) can reveal any fatty change in a lesion and can also differentiate macroscopic fat from intracellular and intravoxel fat. Hypodensity on CT may be a sign of invisible fat and MRI can help to diagnose even minute amounts of fat in liver, pancreas, adrenal, musculoskeletal, and omental pseudolesions and lesions. This article will review the superiority of MRI over CT in demonstrating fat in abdominal lesions. PMID:26782156

  3. Correlative CT and anatomic study of the sciatic nerve

    SciTech Connect

    Pech, P.; Haughton, V.

    1985-05-01

    Sciatica can be caused by numerous processes affecting the sciatic nerve or its components within the pelvis including tumors, infectious diseases, aneurysms, fractures, and endometriosis. The CT diagnosis of these causes of sciatica has not been emphasized. This study identified the course and appearance of the normal sciatic nerve in the pelvis by correlating CT and anatomic slices in cadavers. For purposes of discussion, the sciatic nerve complex is conveniently divided into three parts: presacral, muscular, and ischial. Each part is illustrated here by two cryosections with corresponding CT images.

  4. A global CT to US registration of the lumbar spine

    NASA Astrophysics Data System (ADS)

    Nagpal, Simrin; Hacihaliloglu, Ilker; Ungi, Tamas; Rasoulian, Abtin; Osborn, Jill; Lessoway, Victoria A.; Rohling, Robert N.; Borschneck, Daniel P.; Abolmaesumi, Purang; Mousavi, Parvin

    2014-03-01

    During percutaneous lumbar spine needle interventions, alignment of the preoperative computed tomography (CT) with intraoperative ultrasound (US) can augment anatomical visualization for the clinician. We propose an approach to rigidly align CT and US data of the lumbar spine. The approach involves an intensity-based volume registration step, followed by a surface segmentation and a point-based registration of the entire lumbar spine volume. A clinical feasibility study resulted in mean registration error of approximately 3 mm between CT and US data.

  5. Portal vein involvement in hepatocellular carcinoma: dynamic CT features

    SciTech Connect

    Mathieu, D.; Grenier, P.; Larde, D.; Vasile, N.

    1984-07-01

    The authors conducted a retrospective examination of 62 hepatocellular carcinomas, taking dynamic CT scans of selected sections after an intravenous contrast bolus. The proximal portal vein was involved in 40% of cases and distal segment in 16%. Angiographic correlation was available in 23 patients. The characteristic appearance of tumor within the portal vein was noted in many cases; in others, distinction between tumor and bland thrombus could not be made. Peripheral portal vein obstruction was suggested when a small, hypervascular tumor became hypodense during the portal phase of CT. The frequency and significance of these CT signs of portal vein involvement are discussed.

  6. MR Evaluation of the Nontraumatic Acute Abdomen with CT Correlation.

    PubMed

    Bannas, Peter; Pickhardt, Perry J

    2015-11-01

    Cross-sectional imaging plays a crucial role in the triage of patients with acute abdominal pain. Ionizing radiation exposure is a recognized drawback of computed tomography (CT), the primary imaging technique. MR imaging is a promising alternative to CT; it provides excellent image quality with high-contrast resolution without the disadvantages of ionizing radiation and iodinated contrast. This article provides a basic overview of the typical MR findings of the most frequent disease entities encountered in the setting of the nontraumatic acute abdomen, including direct comparison with CT findings to familiarize the readers with these same findings on MR. PMID:26526441

  7. Bone SPECT/CT of Femoral Head Subchondral Insufficiency Fracture.

    PubMed

    Motomura, Goro; Yamamoto, Takuaki; Karasuyama, Kazuyuki; Iwamoto, Yukihide

    2015-09-01

    Subchondral insufficiency fracture of the femoral head may be confused with osteonecrosis, mainly because of radiological overlap. SPECT/CT with Tc-99 m hydroxymethylene diphosphonate images in 7 patients with subchondral insufficiency fracture were retrospectively reviewed and compared with those from 11 patients with symptomatic early osteonecrosis. In all of the hips with subchondral insufficiency fracture, SPECT/CT showed increased uptake at the subchondral lesions of the femoral head. On the other hand, in all of the hips with osteonecrosis, absence of uptake was confirmed at the subchondral lesions. SPECT/CT may assist in differentiating subchondral insufficiency fracture from osteonecrosis. PMID:26164176

  8. A simple method for labeling CT images with respiratory states

    SciTech Connect

    Berlinger, Kajetan; Sauer, Otto; Vences, Lucia; Roth, Michael

    2006-09-15

    A method is described for labeling CT images with their respiratory state by a needle, connected to the patient's chest/abdomen. By means of a leverage the needle follows the abdominal respiratory motion. The needle is visible as a blurred spot in every CT slice. The method was tested with nine patients. A series of volume scans during free breathing was performed. The detected positions of the moving needle in every single slice were compared to each other thus enabling respiratory state assignment. The tool is an inexpensive alternative to complex respiratory measuring tools for four dimensional (4D) CT and was greatly accepted in the clinic due to its simplicity.

  9. Freezing effect on brain density in postmortem CT.

    PubMed

    Sugimoto, Miyu; Hyodoh, Hideki; Rokukawa, Masumi; Kanazawa, Ayumi; Murakami, Rina; Shimizu, Junya; Okazaki, Shunichiro; Mizuo, Keisuke; Watanabe, Satoshi

    2016-01-01

    Two 60-year-old males were found at their homes whose bodies had deteriorated due to putrefaction. To prevent worm invasion and minimize deterioration, dry ice was used prior to the autopsy investigation. Prior to autopsy, postmortem CT demonstrated a decreased density in brain parenchyma at the dry-iced side, and autopsy revealed deteriorated brain parenchyma with frozen effect (presented like sherbet). Moreover, the deteriorated cerebral parenchyma maintained their structure and they were evaluated by cutting. When lower CT density presents in postmortem CT, the freezing effect may need to be considered and the physician should evaluate the cadaver's postmortem condition to prevent misdiagnoses. PMID:26832379

  10. Classification of CT-brain slices based on local histograms

    NASA Astrophysics Data System (ADS)

    Avrunin, Oleg G.; Tymkovych, Maksym Y.; Pavlov, Sergii V.; Timchik, Sergii V.; Kisała, Piotr; Orakbaev, Yerbol

    2015-12-01

    Neurosurgical intervention is a very complicated process. Modern operating procedures based on data such as CT, MRI, etc. Automated analysis of these data is an important task for researchers. Some modern methods of brain-slice segmentation use additional data to process these images. Classification can be used to obtain this information. To classify the CT images of the brain, we suggest using local histogram and features extracted from them. The paper shows the process of feature extraction and classification CT-slices of the brain. The process of feature extraction is specialized for axial cross-section of the brain. The work can be applied to medical neurosurgical systems.

  11. CT radiation dose optimization and estimation: an update for radiologists.

    PubMed

    Goo, Hyun Woo

    2012-01-01

    In keeping with the increasing utilization of CT examinations, the greater concern about radiation hazards from examinations has been addressed. In this regard, CT radiation dose optimization has been given a great deal of attention by radiologists, referring physicians, technologists, and physicists. Dose-saving strategies are continuously evolving in terms of imaging techniques as well as dose management. Consequently, regular updates of this issue are necessary especially for radiologists who play a pivotal role in this activity. This review article will provide an update on how we can optimize CT dose in order to maximize the benefit-to-risk ratio of this clinically useful diagnostic imaging method. PMID:22247630

  12. CT image retrieval using dual tree complex wavelet packet transform

    NASA Astrophysics Data System (ADS)

    Kokare, Manesh

    2010-02-01

    In this paper, novel method based on Dual Tree Complex Wavelet Packet Transform (DT-CWPT) to analyze texture of Computer Tomography (CT) images and extract the corresponding feature vectors for content based medical image retrieval is proposed. This is mainly because of DT-CWPT characterizes textural property of CT images in better way. The feature vectors of CT images are extracted by measuring energy and standard deviation of DT-CWPT subband. These features are used to facilitate content based medical image retrieval (CBMIR).The proposed method outperforms than existing available methods.

  13. Spectral optimization for micro-CT

    SciTech Connect

    Hupfer, Martin; Nowak, Tristan; Brauweiler, Robert; Eisa, Fabian; Kalender, Willi A.

    2012-06-15

    Purpose: To optimize micro-CT protocols with respect to x-ray spectra and thereby reduce radiation dose at unimpaired image quality. Methods: Simulations were performed to assess image contrast, noise, and radiation dose for different imaging tasks. The figure of merit used to determine the optimal spectrum was the dose-weighted contrast-to-noise ratio (CNRD). Both optimal photon energy and tube voltage were considered. Three different types of filtration were investigated for polychromatic x-ray spectra: 0.5 mm Al, 3.0 mm Al, and 0.2 mm Cu. Phantoms consisted of water cylinders of 20, 32, and 50 mm in diameter with a central insert of 9 mm which was filled with different contrast materials: an iodine-based contrast medium (CM) to mimic contrast-enhanced (CE) imaging, hydroxyapatite to mimic bone structures, and water with reduced density to mimic soft tissue contrast. Validation measurements were conducted on a commercially available micro-CT scanner using phantoms consisting of water-equivalent plastics. Measurements on a mouse cadaver were performed to assess potential artifacts like beam hardening and to further validate simulation results. Results: The optimal photon energy for CE imaging was found at 34 keV. For bone imaging, optimal energies were 17, 20, and 23 keV for the 20, 32, and 50 mm phantom, respectively. For density differences, optimal energies varied between 18 and 50 keV for the 20 and 50 mm phantom, respectively. For the 32 mm phantom and density differences, CNRD was found to be constant within 2.5% for the energy range of 21-60 keV. For polychromatic spectra and CMs, optimal settings were 50 kV with 0.2 mm Cu filtration, allowing for a dose reduction of 58% compared to the optimal setting for 0.5 mm Al filtration. For bone imaging, optimal tube voltages were below 35 kV. For soft tissue imaging, optimal tube settings strongly depended on phantom size. For 20 mm, low voltages were preferred. For 32 mm, CNRD was found to be almost independent of

  14. Serial CT Findings of Paragonimus Infested Dogs and the Micro-CT Findings of the Worm Cysts

    PubMed Central

    Lee, Chang Hyun; Goo, Jin Mo; Lee, Hyun Ju; Hong, Sung-Tae; Shen, Cheng Hua; Chung, Doo Hyun; Son, Kyu Ri; Chang, Jung Min; Eo, Hong

    2007-01-01

    Objective To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. Materials and Methods This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. Results The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. Conclusion The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus. PMID:17923779

  15. Energy Dependence of Measured CT Numbers on Substituted Materials Used for CT Number Calibration of Radiotherapy Treatment Planning Systems

    PubMed Central

    Mahmoudi, Reza; Jabbari, Nasrollah; aghdasi, Mehdi; Khalkhali, Hamid Reza

    2016-01-01

    Introduction For accurate dose calculations, it is necessary to provide a correct relationship between the CT numbers and electron density in radiotherapy treatment planning systems (TPSs). The purpose of this study was to investigate the energy dependence of measured CT numbers on substituted materials used for CT number calibration of radiotherapy TPSs and the resulting errors in the treatment planning calculation doses. Materials and Methods In this study, we designed a cylindrical water phantom with different materials used as tissue equivalent materials for the simulation of tissues and obtaining the related CT numbers. For evaluating the effect of CT number variations of substituted materials due to energy changing of scanner (kVp) on the dose calculation of TPS, the slices of the scanned phantom at three kVp's were imported into the desired TPSs (MIRS and CorePLAN). Dose calculations were performed on two TPSs. Results The mean absolute percentage differences between the CT numbers of CT scanner and two treatment planning systems for all the samples were 3.22%±2.57% for CorePLAN and 2.88%±2.11% for MIRS. It was also found that the maximum absolute percentage difference between all of the calculated doses from each photon beam of linac (6 and 15 MV) at three kVp's was less than 1.2%. Discussion The present study revealed that, for the materials with effective low atomic number, the mean CT number increased with increasing energy, which was opposite for the materials with an effective high atomic number. We concluded that the tissue substitute materials had a different behavior in the energy ranges from 80 to 130 kVp. So, it is necessary to consider the energy dependence of the substitute materials used for the measurement or calibration of CT number for radiotherapy treatment planning systems. PMID:27391672

  16. 75 FR 66428 - Proposed Collection; Comment Request for Form CT-2

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-28

    ... Internal Revenue Service Proposed Collection; Comment Request for Form CT-2 AGENCY: Internal Revenue...(c)(2)(A)). Currently, the IRS is soliciting comments concerning Form CT-2, Employee Representative's... Number: Form CT-2. Abstract: Employee representatives file Form CT-2 quarterly to report compensation...

  17. Multi-detector row CT of pancreatic islet cell tumors.

    PubMed

    Horton, Karen M; Hruban, Ralph H; Yeo, Charles; Fishman, Elliot K

    2006-01-01

    Pancreatic islet cell tumors (ICTs) are neuroendocrine neoplasms that produce and secrete hormones to a variable degree. These neoplasms can present a diagnostic challenge, both clinically and radiologically. ICTs can be classified as either syndromic or nonsyndromic on the basis of their clinical manifestations. Multi-detector row computed tomography (CT) plays an important role in the diagnosis and staging of both syndromic and nonsyndromic ICTs. In general, syndromic ICTs are less than 3 cm in size. They are typically hyperenhancing and are usually best seen on CT scans obtained during the arterial phase. Nonsyndromic ICTs tend to be larger than syndromic ICTs at presentation and are more likely to be cystic or necrotic. It is important for the radiologist to be familiar with appropriate CT protocol for the evaluation of patients with suspected pancreatic ICT and to understand the variable CT appearances of these neoplasms. PMID:16549609

  18. PET/CT Imaging in Mouse Models of Myocardial Ischemia

    PubMed Central

    Gargiulo, Sara; Greco, Adelaide; Gramanzini, Matteo; Petretta, Maria Piera; Ferro, Adele; Larobina, Michele; Panico, Mariarosaria; Brunetti, Arturo; Cuocolo, Alberto

    2012-01-01

    Different species have been used to reproduce myocardial infarction models but in the last years mice became the animals of choice for the analysis of several diseases, due to their short life cycle and the possibility of genetic manipulation. Many techniques are currently used for cardiovascular imaging in mice, including X-ray computed tomography (CT), high-resolution ultrasound, magnetic resonance imaging, and nuclear medicine procedures. Cardiac positron emission tomography (PET) allows to examine noninvasively, on a molecular level and with high sensitivity, regional changes in myocardial perfusion, metabolism, apoptosis, inflammation, and gene expression or to measure changes in anatomical and functional parameters in heart diseases. Currently hybrid PET/CT scanners for small laboratory animals are available, where CT adds high-resolution anatomical information. This paper reviews mouse models of myocardial infarction and discusses the applications of dedicated PET/CT systems technology, including animal preparation, anesthesia, radiotracers, and images postprocessing. PMID:22505813

  19. PET/CT imaging in mouse models of myocardial ischemia.

    PubMed

    Gargiulo, Sara; Greco, Adelaide; Gramanzini, Matteo; Petretta, Maria Piera; Ferro, Adele; Larobina, Michele; Panico, Mariarosaria; Brunetti, Arturo; Cuocolo, Alberto

    2012-01-01

    Different species have been used to reproduce myocardial infarction models but in the last years mice became the animals of choice for the analysis of several diseases, due to their short life cycle and the possibility of genetic manipulation. Many techniques are currently used for cardiovascular imaging in mice, including X-ray computed tomography (CT), high-resolution ultrasound, magnetic resonance imaging, and nuclear medicine procedures. Cardiac positron emission tomography (PET) allows to examine noninvasively, on a molecular level and with high sensitivity, regional changes in myocardial perfusion, metabolism, apoptosis, inflammation, and gene expression or to measure changes in anatomical and functional parameters in heart diseases. Currently hybrid PET/CT scanners for small laboratory animals are available, where CT adds high-resolution anatomical information. This paper reviews mouse models of myocardial infarction and discusses the applications of dedicated PET/CT systems technology, including animal preparation, anesthesia, radiotracers, and images postprocessing. PMID:22505813

  20. Development of lung cancer CT screening operating support system

    NASA Astrophysics Data System (ADS)

    Ishigaki, Rikuta; Hanai, Kozou; Suzuki, Masahiro; Kawata, Yoshiki; Niki, Noboru; Eguchi, Kenji; Kakinuma, Ryutaro; Moriyama, Noriyuki

    2009-02-01

    In Japan, lung cancer death ranks first among men and third among women. Lung cancer death is increasing yearly, thus early detection and treatment are needed. For this reason, CT screening for lung cancer has been introduced. The CT screening services are roughly divided into three sections: office, radiology and diagnosis sections. These operations have been performed through paper-based or a combination of paper-based and an existing electronic health recording system. This paper describes an operating support system for lung cancer CT screening in order to make the screening services efficient. This operating support system is developed on the basis of 1) analysis of operating processes, 2) digitalization of operating information, and 3) visualization of operating information. The utilization of the system is evaluated through an actual application and users' survey questionnaire obtained from CT screening centers.

  1. FDG PET-CT of gynecologic cancers: pearls and pitfalls.

    PubMed

    Prabhakar, Hima B; Kraeft, Jessica J; Schorge, John O; Scott, James A; Lee, Susanna I

    2015-10-01

    FDG PET-CT plays an important role in treatment planning and in prognosis assessment of gynecologic cancer patients. Detection of hypermetabolic tissue with FDG PET, when combined with the high spatial resolution of CT, results in improved cancer detection and localization not afforded by either modality independently. This article is a primer for a radiologist performing PET-CT on gynecologic cancer patients and includes the imaging protocol, normal pattern of FDG distribution in the female pelvis and the lymph node drainage pathways from the gynecologic organs. Clinically relevant imaging findings that should be included in the report are discussed. Case examples illustrate how potential errors in exam interpretation can be avoided by concurrently performing a high-quality diagnostic CT with the FDG PET scan and by analyzing both the stand-alone and the fusion images. PMID:25680500

  2. 75 FR 29590 - Connecticut Disaster Number CT-00015

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster Number CT-00015 AGENCY: Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public...

  3. 78 FR 35757 - Drawbridge Operation Regulations; Connecticut River, Westport, CT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulations; Connecticut River, Westport, CT AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation from regulations. SUMMARY: The...

  4. CT of the normal and abnormal parametria in cervical cancer

    SciTech Connect

    Vick, C.W.; Walsh, J.W.; Wheelock, J.B.; Brewer, W.H.

    1984-09-01

    To evaluate CT criteria for differentiating a cervical cancer confined to the cervix from a lesion that invades the parametria, 16 patients with newly diagnosed, untreated cervical cancer were studied with CT. Twenty-five parameria were confined by radical hysterectomy, transvaginal parametrial fine-needle aspiration cytology, or excretory urography. In 17 tumor-positive parametria, CT findings associated with parametrial tumor invasion were: 1) irregularity or poor definition of the lateral cervical margins; 2) prominent parametrial soft-tissue strands; 3) obliteration of the periureteral fat plane; and 4) an eccentric parametrial soft-tissue mass. Irregularity of the cervical margins and prominent parametrial strands were seen most commonly with parametrial tumor invasion, but were also occasionally seen with parametrial inflammation. On the basis of the criteria developed in this report, CT may be used as an adjunct to the physical examination in differentiating stage I cervical cancer from more advanced disease in selected patients.

  5. Utility of CT in detecting postpneumonectomy carcinoma recurrence

    SciTech Connect

    Glazer, H.S.; Aronberg, D.J.; Sagel, S.S.; Emami, B.

    1984-03-01

    After pneumonectomy for bronchogenic carcinoma, detection of recurrent disease in the ipsilateral hemithorax or mediastinum is often difficult. The authors discuss the utility of CT in the evaluation of 18 postpneumonectomy patients who had developed new clinical symptoms. In six patients without documented tumor recurrence, CT demonstrated a normal postpneumonectomy appearance. In the other 12, CT confirmed the clinical impression of recurrent neoplasm (10 prospectively, two retrospectively), which appeared either as enlarged mediastinal lymph nodes or as a soft-tissue mass projecting into the normal near-water-density postpneumonectomy space. In only five of these patients were plain chest radiographs suggestive of recurrence (two prospectively, three retrospectively). The accurate assessment of the presence and extent of recurrent neoplasm by CT was important in planning radiotherapy in eight patients.

  6. Noninvasive Physiologic Assessment of Coronary Stenoses Using Cardiac CT

    PubMed Central

    Fan, Zhanming

    2015-01-01

    Coronary CT angiography (CCTA) has become an important noninvasive imaging modality in the diagnosis of coronary artery disease (CAD). CCTA enables accurate evaluation of coronary artery stenosis. However, CCTA provides limited information on the physiological significance of stenotic lesions. A noninvasive “one-stop-shop” diagnostic test that can provide both anatomical significance and functional significance of stenotic lesions would be beneficial in the diagnosis and management of CAD. Recently, with the introduction of novel techniques, such as myocardial CT perfusion, CT-derived fractional flow reserve (FFRCT), and transluminal attenuation gradient (TAG), CCTA has emerged as a noninvasive method for the assessment of both anatomy of coronary lesions and its physiological consequences during a single study. This review provides an overview of the current status of new CT techniques for the physiologic assessments of CAD. PMID:25685790

  7. [Rational CT diagnosis before operations on the paranasal sinuses].

    PubMed

    Koitschev, A; Baumann, I; Remy, C T; Dammann, F

    2002-03-01

    Movement or metal artefacts as well as the relatively high radiation exposure of both the axial and the coronal scan are disadvantages of computed tomography. A single spiral CT scan with a secondary reformation replacing the second CT scan might solve these problems. The goal of this project was to compare the diagnostic value of primary spiral CT scans of paranasal sinuses with secondary reformations. These were evaluated by ENT surgeons as well as radiologists. We performed axial and coronal spiral-CT's of paranasal sinuses in 80 patients. The secondary coronal and axial reformations were calculated with 2 mm image sections. Although a reduced resolution was observed in the secondary reformations, this did not compromise the detection of important anatomical features. Image deterioration due to artifacts was significantly reduced. PMID:11975076

  8. Full-Body CT Scans - What You Need to Know

    MedlinePlus

    ... FDA Submit search Popular Content Home Food Drugs Medical Devices Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary ... for assuring the safety and effectiveness of such medical devices, and it prohibits manufacturers of CT systems to ...

  9. 78 FR 7848 - Connecticut Disaster Number CT-00028

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Connecticut Disaster Number CT-00028 AGENCY: U.S. Small Business Administration. ACTION: Amendment...: U.S. Small Business Administration, Processing and Disbursement Center, 14925 Kingsport Road,...

  10. Coronary thrombus detected by cardiac CT angiography before cardiac catheterization.

    PubMed

    Slim, Ahmad M; Slim, Jennifer N; Haney, Brian R; Shry, Eric A

    2010-11-01

    A patient presented with a complaint of pleuritic chest discomfort with elevated cardiac biomarkers. After a cardiac magnetic resonance imaging scan for the suspicion of myopericarditis showed a potential myocardial infarct, a coronary CT scan was performed. This revealed a thrombus of the left anterior descending artery. Cardiac catheterization confirmed the findings, and a small clot was removed. To our knowledge, this is the first reported case of coronary thrombus being detected by CT angiography with cardiac catheterization correlation. Coronary CT angiography has been increasingly used to evaluate acute chest pain with a negative predictive value close to 100%. In a young patient with suspicion of myopericarditis, CT angiography proved to be useful in diagnosing thrombus in the coronary tree. PMID:20463613

  11. CT of ruptured aneurysm of aberrant right subclavian artery.

    PubMed

    Vega, A; Ortíz, A; Longo, J M; Pagola, M A

    1987-01-01

    This paper presents the first description of a ruptured aneurysm of an aberrant right subclavian artery. CT clearly demonstrated the vascular malformation as well as the existence of a bilateral hemothorax. PMID:3102065

  12. Quantification of ring artifact visibility in CT

    NASA Astrophysics Data System (ADS)

    Persson, Mats; Meyer, Bettina; Bornefalk, Hans; Danielsson, Mats

    2012-03-01

    Ring artifacts appear in computed tomography images if there are too large inhomogeneities between different detector elements. The question of how large inhomogeneities are acceptable is gaining in importance due to the development of energy discriminating photon counting CT, where detector homogeneity is an important design parameter. We propose using the systematic-to-statistical error quotient q, defined as the variance of the expected log-normalized count number between detector elements (dels) divided by the variance of log-normalized count numbers measured with the same del, as a metric of ring artifact visibility. With a simple observer study using simulated images, it is shown that rings are visible in the reconstructed image if q exceeds a threshold which lies close to 1.2 • 10-3 for 1500 detector elements and 2000 projection angles. It is also shown by visual inspection of simulated images that the threshold value is, to a good approximation, inversely proportional to the number of angle measurements and independent of the number of detector elements. The results suggest that a simple oberver study, together with these scaling relationships, is sufficient for establishing sinogram homogeneity requirements for a particular reconstruction method.

  13. Automatic Lumbar Spondylolisthesis Measurement in CT Images.

    PubMed

    Liao, Shu; Zhan, Yiqiang; Dong, Zhongxing; Yan, Ruyi; Gong, Liyan; Zhou, Xiang Sean; Salganicoff, Marcos; Fei, Jun

    2016-07-01

    Lumbar spondylolisthesis is one of the most common spinal diseases. It is caused by the anterior shift of a lumbar vertebrae relative to subjacent vertebrae. In current clinical practices, staging of spondylolisthesis is often conducted in a qualitative way. Although meyerding grading opens the door to stage spondylolisthesis in a more quantitative way, it relies on the manual measurement, which is time consuming and irreproducible. Thus, an automatic measurement algorithm becomes desirable for spondylolisthesis diagnosis and staging. However, there are two challenges. 1) Accurate detection of the most anterior and posterior points on the superior and inferior surfaces of each lumbar vertebrae. Due to the small size of the vertebrae, slight errors of detection may lead to significant measurement errors, hence, wrong disease stages. 2) Automatic localize and label each lumbar vertebrae is required to provide the semantic meaning of the measurement. It is difficult since different lumbar vertebraes have high similarity of both shape and image appearance. To resolve these challenges, a new auto measurement framework is proposed with two major contributions: First, a learning based spine labeling method that integrates both the image appearance and spine geometry information is designed to detect lumbar vertebrae. Second, a hierarchical method using both the population information from atlases and domain-specific information in the target image is proposed for most anterior and posterior points positioning. Validated on 258 CT spondylolisthesis patients, our method shows very similar results to manual measurements by radiologists and significantly increases the measurement efficiency. PMID:26849859

  14. Accelerated Compressed Sensing Based CT Image Reconstruction

    PubMed Central

    Hashemi, SayedMasoud; Beheshti, Soosan; Gill, Patrick R.; Paul, Narinder S.; Cobbold, Richard S. C.

    2015-01-01

    In X-ray computed tomography (CT) an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS) enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization. PMID:26167200

  15. Highly accurate fast lung CT registration

    NASA Astrophysics Data System (ADS)

    Rühaak, Jan; Heldmann, Stefan; Kipshagen, Till; Fischer, Bernd

    2013-03-01

    Lung registration in thoracic CT scans has received much attention in the medical imaging community. Possible applications range from follow-up analysis, motion correction for radiation therapy, monitoring of air flow and pulmonary function to lung elasticity analysis. In a clinical environment, runtime is always a critical issue, ruling out quite a few excellent registration approaches. In this paper, a highly efficient variational lung registration method based on minimizing the normalized gradient fields distance measure with curvature regularization is presented. The method ensures diffeomorphic deformations by an additional volume regularization. Supplemental user knowledge, like a segmentation of the lungs, may be incorporated as well. The accuracy of our method was evaluated on 40 test cases from clinical routine. In the EMPIRE10 lung registration challenge, our scheme ranks third, with respect to various validation criteria, out of 28 algorithms with an average landmark distance of 0.72 mm. The average runtime is about 1:50 min on a standard PC, making it by far the fastest approach of the top-ranking algorithms. Additionally, the ten publicly available DIR-Lab inhale-exhale scan pairs were registered to subvoxel accuracy at computation times of only 20 seconds. Our method thus combines very attractive runtimes with state-of-the-art accuracy in a unique way.

  16. Mixed Confidence Estimation for Iterative CT Reconstruction.

    PubMed

    Perlmutter, David S; Kim, Soo Mee; Kinahan, Paul E; Alessio, Adam M

    2016-09-01

    Dynamic (4D) CT imaging is used in a variety of applications, but the two major drawbacks of the technique are its increased radiation dose and longer reconstruction time. Here we present a statistical analysis of our previously proposed Mixed Confidence Estimation (MCE) method that addresses both these issues. This method, where framed iterative reconstruction is only performed on the dynamic regions of each frame while static regions are fixed across frames to a composite image, was proposed to reduce computation time. In this work, we generalize the previous method to describe any application where a portion of the image is known with higher confidence (static, composite, lower-frequency content, etc.) and a portion of the image is known with lower confidence (dynamic, targeted, etc). We show that by splitting the image space into higher and lower confidence components, MCE can lower the estimator variance in both regions compared to conventional reconstruction. We present a theoretical argument for this reduction in estimator variance and verify this argument with proof-of-principle simulations. We also propose a fast approximation of the variance of images reconstructed with MCE and confirm that this approximation is accurate compared to analytic calculations of and multi-realization image variance. This MCE method requires less computation time and provides reduced image variance for imaging scenarios where portions of the image are known with more certainty than others allowing for potentially reduced radiation dose and/or improved dynamic imaging. PMID:27008663

  17. Diagnosing acute lacunar infarction using CT perfusion.

    PubMed

    Cao, Wenjie; Yassi, Nawaf; Sharma, Gagan; Yan, Bernard; Desmond, Patricia M; Davis, Stephen M; Campbell, Bruce C V

    2016-07-01

    The value of CT perfusion (CTP) in detecting acute lacunar infarcts (LACI) has not been well established. We tested the sensitivity of CTP for LACI. CTP maps of consecutive stroke patients from 2009-2013 were examined. MRI diffusion imaging was used to identify those with LACI. Two stroke neurologists independently evaluated the CTP maps for evidence of a perfusion lesion in a deep perforating artery territory. Cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) and time to maximum (Tmax) maps were first examined in isolation and then in combination. Inter-observer agreement was measured using Cohen's κ. The lesions identified were later confirmed against the diffusion MRI reference and the sensitivity and specificity of CTP maps calculated. A total of 63 patient scans were analysed. There were 32 patients with MRI-confirmed LACI within the coverage of CTP; 18 in the striatum, 10 thalamic, and four in the corona radiata. Another 31 patients had normal MRI. Inter-rater agreement was good (κ=0.83). Sensitivity (blinded consensus) was highest for MTT (56.2%) compared to Tmax (25%, p<0.001), CBV (9.3%, p=0.021) and CBF (43.7%, p<0.001). MTT maps enable detection of a significant proportion of LACI using CTP. PMID:26899357

  18. Segmentation-based CT image compression

    NASA Astrophysics Data System (ADS)

    Thammineni, Arunoday; Mukhopadhyay, Sudipta; Kamath, Vidya

    2004-04-01

    The existing image compression standards like JPEG and JPEG 2000, compress the whole image as a single frame. This makes the system simple but inefficient. The problem is acute for applications where lossless compression is mandatory viz. medical image compression. If the spatial characteristics of the image are considered, it can give rise to a more efficient coding scheme. For example, CT reconstructed images have uniform background outside the field of view (FOV). Even the portion within the FOV can be divided as anatomically relevant and irrelevant parts. They have distinctly different statistics. Hence coding them separately will result in more efficient compression. Segmentation is done based on thresholding and shape information is stored using 8-connected differential chain code. Simple 1-D DPCM is used as the prediction scheme. The experiments show that the 1st order entropies of images fall by more than 11% when each segment is coded separately. For simplicity and speed of decoding Huffman code is chosen for entropy coding. Segment based coding will have an overhead of one table per segment but the overhead is minimal. Lossless compression of image based on segmentation resulted in reduction of bit rate by 7%-9% compared to lossless compression of whole image as a single frame by the same prediction coder. Segmentation based scheme also has the advantage of natural ROI based progressive decoding. If it is allowed to delete the diagnostically irrelevant portions, the bit budget can go down as much as 40%. This concept can be extended to other modalities.

  19. Dynamic bowtie for fan-beam CT.

    PubMed

    Liu, Fenglin; Wang, Ge; Cong, Wenxiang; Hsieh, Scott S; Pelc, Norbert J

    2013-01-01

    A bowtie is a filter used to shape an x-ray beam and equalize its flux reaching different detector channels. For development of spectral CT with energy discriminating photon-counting (EDPC) detectors, here we propose and evaluate a dynamic bowtie for performance optimization based on a patient model or a scout scan. With a mechanical rotation of a dynamic bowtie and an adaptive adjustment of an x-ray source flux, an x-ray beam intensity profile can be modulated. First, a mathematical model for dynamic bowtie filtering is established for an elliptical section in fan-beam geometry, and the contour of the optimal bowtie is derived. Then, numerical simulation is performed to compare the performance of the dynamic bowtie in the cases of an ideal phantom and a realistic cross-section relative to the counterparts without any bowtie and with a fixed bowtie respectively. Our dynamic bowtie can equalize the expected numbers of photons in the case of an ideal phantom. In practical cases, our dynamic bowtie can effectively reduce the dynamic range of detected signals inside the field of view. Although our design is optimized for an elliptical phantom, the resultant dynamic bowtie can be applied to a real fan-beam scan if the underlying cross-section can be approximated as an ellipse. Furthermore, our design methodology can be applied to specify an optimized dynamic bowtie for any cross-section of a patient, preferably using rapid prototyping technology. PMID:24191994

  20. [CT colonography: techniques of visualization and findings].

    PubMed

    Wessling, J; Heindel, W

    2008-02-01

    Evaluation and interpretation of CT colonography is based on both 2D and 3D techniques. The 2D techniques are popular mainly because the time needed for evaluation is short. The 3D techniques allow better definition than the 2D techniques, especially of polyps close to folds or at the base of a fold. The evaluation strategies generally accepted so far (primarily 2D, with 3D for problem cases, or vice versa) demand knowledge of both 2D and 3D techniques. Newer 3D visualization techniques help make it possible to acquire more complete and faster recording particularly of areas that are not easily accessible to endoscopic examination. These user-friendly developments are thus well suited to improving the detection and the security of detection of polyps. It must be remembered that experience and the knowledge of associated artifacts and the limitations they can impose on diagnosis are prime requirements for the implementation of such visualization techniques. PMID:18210054

  1. Automated vertebra identification in CT images

    NASA Astrophysics Data System (ADS)

    Ehm, Matthias; Klinder, Tobias; Kneser, Reinhard; Lorenz, Cristian

    2009-02-01

    In this paper, we describe and compare methods for automatically identifying individual vertebrae in arbitrary CT images. The identification is an essential precondition for a subsequent model-based segmentation, which is used in a wide field of orthopedic, neurological, and oncological applications, e.g., spinal biopsies or the insertion of pedicle screws. Since adjacent vertebrae show similar characteristics, an automated labeling of the spine column is a very challenging task, especially if no surrounding reference structures can be taken into account. Furthermore, vertebra identification is complicated due to the fact that many images are bounded to a very limited field of view and may contain only few vertebrae. We propose and evaluate two methods for automatically labeling the spine column by evaluating similarities between given models and vertebral objects. In one method, object boundary information is taken into account by applying a Generalized Hough Transform (GHT) for each vertebral object. In the other method, appearance models containing mean gray value information are registered to each vertebral object using cross and local correlation as similarity measures for the optimization function. The GHT is advantageous in terms of computational performance but cuts back concerning the identification rate. A correct labeling of the vertebral column has been successfully performed on 93% of the test set consisting of 63 disparate input images using rigid image registration with local correlation as similarity measure.

  2. Classification of microcalcifications using micro-CT

    NASA Astrophysics Data System (ADS)

    Temmermans, Frederik; Jansen, Bart; Willekens, Inneke; Van de Casteele, Elke; Deklerck, Rudi; Schelkens, Peter; De Mey, Johan

    2013-09-01

    Microcalcifications are tiny spots of calcium deposit that often occur in female breasts. Microcalcifications are common in healthy woman, but they often are an early sign of breast cancer. On a mammogram; the current standard of care for breast screening; calcifications appear as tiny white dots. They may occur scattered throughout the breast or grouped in clusters. Radiologists determine the suspiciousness based upon several factors, including position, frequency, grouping, evolution compared to prior studies and shape. In this paper, we study micro-CT images of biopsy samples containing microcalcifications. The scanner delivers 3D images with a voxel size of 8.66 μm, i.e. ca. 8 times the spatial resolution of a contemporary digital mammogram. We propose an automated binary classification method of the samples, based upon shape analysis of the microcalcifications. The study is performed on a set of 50 benign and 50 malign samples preserved in paraffin. The ground truth of the classification is based upon anapathological investigation of the paraffin blocks. The results show a sensitivity, i.e. the percentage of correctly classified malign samples, of up to 98% with a specificity of 40%.

  3. CT Texture Analysis of Renal Masses

    PubMed Central

    Raman, Siva P.; Chen, Yifei; Schroeder, James L.; Huang, Peng; Fishman, Elliot K.

    2015-01-01

    Rationale and Objectives Computed tomography texture analysis (CTTA) allows quantification of heterogeneity within a region of interest. This study investigates the possibility of distinguishing between several common renal masses using CTTA-derived parameters by developing and validating a predictive model. Materials and Methods CTTA software was used to analyze 20 clear cell renal cell carcinomas (RCCs), 20 papillary RCCs, 20 oncocytomas, and 20 renal cysts. Regions of interest were drawn around each mass on multiple slices in the arterial, venous, and delayed phases on renal mass protocol CT scans. Unfiltered images and spatial band-pass filtered images were analyzed to quantify heterogeneity. Random forest method was used to construct a predictive model to classify lesions using quantitative parameters. The model was externally validated on a separate set of 19 unknown cases. Results The random forest model correctly categorized oncocytomas in 89% of cases (sensitivity = 89%, specificity = 99%), clear cell RCCs in 91% of cases (sensitivity = 91%, specificity = 97%), cysts in 100% of cases (sensitivity = 100%, specificity = 100%), and papillary RCCs in 100% of cases (sensitivity = 100%, specificity = 98%). Conclusions CTTA, in conjunction with random forest modeling, demonstrates promise as a tool to characterize lesions. Various renal masses were accurately classified using quantitative information derived from routine scans. PMID:25239842

  4. Diagnostic Accuracy of Fractional Flow Reserve From Anatomic CT Angiography

    PubMed Central

    Min, James K.; Leipsic, Jonathon; Pencina, Michael J.; Berman, Daniel S.; Koo, Bon-Kwon; van Mieghem, Carlos; Erglis, Andrejs; Lin, Fay Y.; Dunning, Allison M.; Apruzzese, Patricia; Budoff, Matthew J.; Cole, Jason H.; Jaffer, Farouc A.; Leon, Martin B.; Malpeso, Jennifer; John Mancini, G. B.; Park, Seung-Jung; Schwartz, Robert S.; Shaw, Leslee J.; Mauri, Laura

    2014-01-01

    Context Coronary computed tomographic (CT) angiography is a noninvasive anatomic test for diagnosis of coronary stenosis that does not determine whether a stenosis causes ischemia. In contrast, fractional flow reserve (FFR) is a physiologic measure of coronary stenosis expressing the amount of coronary flow still attainable despite the presence of a stenosis, but it requires an invasive procedure. Noninvasive FFR computed from CT (FFRCT) is a novel method for determining the physiologic significance of coronary artery disease (CAD), but its ability to identify ischemia has not been adequately examined to date. Objective To assess the diagnostic performance of FFRCT plus CT for diagnosis of hemodynamically significant coronary stenosis. Design, Setting, and Patients Multicenter diagnostic performance study involving 252 stable patients with suspected or known CAD from 17 centers in 5 countries who underwent CT, invasive coronary angiography (ICA), FFR, and FFRCT between October 2010 and October 2011. Computed tomography, ICA, FFR, and FFRCT were interpreted in blinded fashion by independent core laboratories. Accuracy of FFRCT plus CT for diagnosis of ischemia was compared with an invasive FFR reference standard. Ischemia was defined by an FFR or FFRCT of 0.80 or less, while anatomically obstructive CAD was defined by a stenosis of 50% or larger on CT and ICA. Main Outcome Measures The primary study outcome assessed whether FFRCT plus CT could improve the per-patient diagnostic accuracy such that the lower boundary of the 1-sided 95% confidence interval of this estimate exceeded 70%. Results Among study participants, 137 (54.4%) had an abnormal FFR determined by ICA. On a per-patient basis, diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of FFRCT plus CT were 73% (95% CI, 67%–78%), 90% (95% CI, 84%–95%), 54% (95% CI, 46%–83%), 67% (95% CI, 60%–74%), and 84% (95% CI, 74%–90%), respectively. Compared

  5. 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.

  6. Calibration of industrial CT using two forest-balls

    NASA Astrophysics Data System (ADS)

    Shi, Yushu; Song, Xu; Li, Shi; Li, Wei; Li, Qi; Chen, Siwen; Shen, Fei; Song, Xiaoping; Gao, Sitian

    2015-02-01

    A small forest-ball was manufactured and calibrated using CMM F25. An industrial CT called Metrotom1500 was calibrated by the small forest-ball and another big forest-ball produced by Carl Zeiss. These two forest-balls were separately measured at two different magnifications of the industrial CT, and the measurement results could meet the maximum permissible error of Metrotom1500.

  7. Adrenal glands in patients with cogenital renal anomalies: CT appearance

    SciTech Connect

    Kenney, P.J.; Robbins, G.L.; Ellis, D.A.; Spirt, B.A.

    1985-04-01

    The CT appearance of the adrenal glands was investigated in 30 patients with congenital renal anomalies. The ipsilateral adrenal was clearly identified in 83% of these patients; in all of them, the adrenal was a paraspinal disk-shaped organ, which appeared linear on CT. Conversely, the adrenals retained their normal shape in a control group of 20 patients with acquired renal atrophy or prior simple nephrectomy.

  8. Pericardial Tamponade Following CT-Guided Lung Biopsy

    SciTech Connect

    Mitchell, Michael J.; Montgomery, Mark; Reiter, Charles G.; Culp, William C.

    2008-07-15

    While not free from hazards, CT-guided biopsy of the lung is a safe procedure, with few major complications. Despite its safety record, however, potentially fatal complications do rarely occur. We report a case of pericardial tamponade following CT-guided lung biopsy. Rapid diagnosis and therapy allowed for complete patient recovery. Physicians who perform this procedure should be aware of the known complications and be prepared to treat them appropriately.

  9. TLD assessment of mouse dosimetry during microCT imaging

    SciTech Connect

    Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

    2008-09-15

    Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm{sup 3} CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0{+-}5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0{+-}6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0{+-}4.0 mGy and 97.0{+-}5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0{+-}5.0 mGy. The author's results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality.

  10. Spleen in Hodgkin disease: diagnostic value of CT

    SciTech Connect

    Strijk, S.P.; Wagener, D.J.T.; Bogman, M.J.J.T.; de Pauw, B.E.; Wobbes, T.

    1985-03-01

    Findings of CT of the spleen were compared with those of histologic examination in 35 patients who had Hodgkin disease. CT provides a simple way to calculate splenic size. This index is also of value in the assessment of the histologic state of the spleen. An accuracy rate of 91%, specificity of 94%, and a sensitivity of 89% in diagnosing splenic localization of lymphoma was found in this study.

  11. TLD assessment of mouse dosimetry during microCT imaging

    PubMed Central

    Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

    2008-01-01

    Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm3 CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0±5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0±6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0±4.0 mGy and 97.0±5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0±5.0 mGy. The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality. PMID:18841837

  12. WebCT, PDS, and Democratic Spaces in Teacher Education

    ERIC Educational Resources Information Center

    Merryfield, Merry M.

    2006-01-01

    This article begins with an overview of how WebCT is used within a Masters in Education (M.Ed.) program in social studies and global education. WebCT is a class management system that allows instructors to choose from a variety of electronic technologies for a single course or integrate coursework across an entire academic program. In the M.Ed.…

  13. TH-C-BRD-06: A Novel MRI Based CT Artifact Correction Method for Improving Proton Range Calculation in the Presence of Severe CT Artifacts

    SciTech Connect

    Park, P; Schreibmann, E; Fox, T; Roper, J; Elder, E; Tejani, M; Crocker, I; Curran, W; Dhabaan, A

    2014-06-15

    Purpose: Severe CT artifacts can impair our ability to accurately calculate proton range thereby resulting in a clinically unacceptable treatment plan. In this work, we investigated a novel CT artifact correction method based on a coregistered MRI and investigated its ability to estimate CT HU and proton range in the presence of severe CT artifacts. Methods: The proposed method corrects corrupted CT data using a coregistered MRI to guide the mapping of CT values from a nearby artifact-free region. First patient MRI and CT images were registered using 3D deformable image registration software based on B-spline and mutual information. The CT slice with severe artifacts was selected as well as a nearby slice free of artifacts (e.g. 1cm away from the artifact). The two sets of paired MRI and CT images at different slice locations were further registered by applying 2D deformable image registration. Based on the artifact free paired MRI and CT images, a comprehensive geospatial analysis was performed to predict the correct CT HU of the CT image with severe artifact. For a proof of concept, a known artifact was introduced that changed the ground truth CT HU value up to 30% and up to 5cm error in proton range. The ability of the proposed method to recover the ground truth was quantified using a selected head and neck case. Results: A significant improvement in image quality was observed visually. Our proof of concept study showed that 90% of area that had 30% errors in CT HU was corrected to 3% of its ground truth value. Furthermore, the maximum proton range error up to 5cm was reduced to 4mm error. Conclusion: MRI based CT artifact correction method can improve CT image quality and proton range calculation for patients with severe CT artifacts.

  14. Expression of MAGE-C1/CT7 and MAGE-C2/CT10 predicts lymph node metastasis in melanoma patients.

    PubMed

    Curioni-Fontecedro, Alessandra; Nuber, Natko; Mihic-Probst, Daniela; Seifert, Burkhardt; Soldini, Davide; Dummer, Reinhard; Knuth, Alexander; van den Broek, Maries; Moch, Holger

    2011-01-01

    MAGE-C1/CT7 and MAGE-C2/CT10 are members of the large MAGE family of cancer-testis (CT) antigens. CT antigens are promising targets for immunotherapy in cancer because their expression is restricted to cancer and germ line cells and a proportion of cancer patients presents with immune responses against CT antigens, which clearly demonstrates their immunogenicity. This study investigates the expression of MAGE-C1/CT7 and MAGE-C2/CT10 in primary and metastatic melanoma. Immunohistochemical staining of tissue microarrays that consisted of 59 primary malignant melanomas of the skin, 163 lymph node and distant melanoma metastases and 68 melanoma cell lines was performed. We found MAGE-C1/CT7 expression in 15 out of 50 (24%) primary melanomas and 15 out of 50 (24%) cell lines, whereas MAGE-C2/CT10 was detected in 17 out of 51 (33%) primary melanomas and 14 out of 68 (17%) cell lines. MAGE-C1/CT7 and MAGE-C2/CT10 were both detected in 40% of melanoma metastases. Patients with MAGE-C1/CT7 or MAGE-C2/CT10 positive primary melanoma had significantly more lymph node metastases (p = 0.005 and p<0.001, resp.). Prediction of lymph node metastasis by MAGE-C1/CT7 and MAGE-C2/CT10 was independent of tumor cell proliferation rate (Ki67 labeling index) in a multivariate analysis (p = 0.01). Our results suggest that the expression of MAGE-C1/CT7 and MAGE-C2/CT10 in primary melanoma is a potent predictor of sentinel lymph node metastasis. PMID:21738656

  15. Expression of MAGE-C1/CT7 and MAGE-C2/CT10 Predicts Lymph Node Metastasis in Melanoma Patients

    PubMed Central

    Mihic-Probst, Daniela; Seifert, Burkhardt; Soldini, Davide; Dummer, Reinhard; Knuth, Alexander; van den Broek, Maries; Moch, Holger

    2011-01-01

    MAGE-C1/CT7 and MAGE-C2/CT10 are members of the large MAGE family of cancer-testis (CT) antigens. CT antigens are promising targets for immunotherapy in cancer because their expression is restricted to cancer and germ line cells and a proportion of cancer patients presents with immune responses against CT antigens, which clearly demonstrates their immunogenicity. This study investigates the expression of MAGE-C1/CT7 and MAGE-C2/CT10 in primary and metastatic melanoma. Immunohistochemical staining of tissue microarrays that consisted of 59 primary malignant melanomas of the skin, 163 lymph node and distant melanoma metastases and 68 melanoma cell lines was performed. We found MAGE-C1/CT7 expression in 15 out of 50 (24%) primary melanomas and 15 out of 50 (24%) cell lines, whereas MAGE-C2/CT10 was detected in 17 out of 51 (33%) primary melanomas and 14 out of 68 (17%) cell lines. MAGE-C1/CT7 and MAGE-C2/CT10 were both detected in 40% of melanoma metastases. Patients with MAGE-C1/CT7 or MAGE-C2/CT10 positive primary melanoma had significantly more lymph node metastases (p = 0.005 and p<0.001, resp.). Prediction of lymph node metastasis by MAGE-C1/CT7 and MAGE-C2/CT10 was independent of tumor cell proliferation rate (Ki67 labeling index) in a multivariate analysis (p = 0.01). Our results suggest that the expression of MAGE-C1/CT7 and MAGE-C2/CT10 in primary melanoma is a potent predictor of sentinel lymph node metastasis. PMID:21738656

  16. Creating an outpatient center of excellence in CT.

    PubMed

    Itri, Jason N; Bakow, Eric; Woods, Jordan

    2014-12-01

    CT examinations represent a substantial portion of the workload for many radiology departments, and optimizing service delivery is a critical function to ensure customer satisfaction. This article describes how the Six Sigma methodology was used in the radiology department at a large academic hospital to improve the patient experience and increase CT capacity while reducing waste and improving staff satisfaction. The 5 distinct phases of Six Sigma are reviewed as they apply to our CT Center of Excellence project: define, measure, analyze, improve, and control. Process metrics used in this project include the percentage of outpatient CT exams started within 5 minutes of the scheduled appointment time, and the number of studies with protocols selected >48 hours before the CT exam is performed. Outcome metrics include monthly department expense per scan and CT Press Ganey "standard test and treatment" mean scores. An approach to developing interventions is described based on identifying critical sources of variation, ranking these by creating risk prioritization numbers, performing root cause analysis, and utilizing the failure mode and effects analysis tool to prioritize possible solutions. Finally, the key features of action plans and a control plan are reviewed. PMID:25467726

  17. Visualisation of the Bonebridge by means of CT and CBCT

    PubMed Central

    2013-01-01

    Background With the Bonebridge, a new bone-anchored hearing aid has been available since March 2012. The objective of the study was to analyse the visualisation of the implant itself as well as its impact on the representation of the bony structures of the petrosal bone in CT, MRI and cone beam CT (CBCT). Methods The Bonebridge was implanted unilaterally in two completely prepared human heads. The radiological imaging by means of CBCT, 64-slice CT, 1.5-T and 3.0-T MRI was conducted both preoperatively and postoperatively. The images were subsequently evaluated from both the ENT medical and nd radiological perspectives. Results As anticipated, no visualisation of the implant or of the petrosal bones could be realised on MRI because of the interactive technology and the magnet artefact. In contrast, an excellent evaluability of the implant itself as well as of the surrounding neurovascular structures (sinus sigmoideus, skull base, middle ear, inner ear, inner auditory canal) was exhibited in both the CT and in the CBCT. Conclusion The Bonebridge can be excellently imaged with the radiological imaging technologies of CT and CBCT. In the process, CBCT shows discrete advantages in comparison with CT. No relevant restrictions in image quality in the evaluation of the bony structures of the petrosal bones could be seen. PMID:24004903

  18. Iterative reconstruction methods in X-ray CT.

    PubMed

    Beister, Marcel; Kolditz, Daniel; Kalender, Willi A

    2012-04-01

    Iterative reconstruction (IR) methods have recently re-emerged in transmission x-ray computed tomography (CT). They were successfully used in the early years of CT, but given up when the amount of measured data increased because of the higher computational demands of IR compared to analytical methods. The availability of large computational capacities in normal workstations and the ongoing efforts towards lower doses in CT have changed the situation; IR has become a hot topic for all major vendors of clinical CT systems in the past 5 years. This review strives to provide information on IR methods and aims at interested physicists and physicians already active in the field of CT. We give an overview on the terminology used and an introduction to the most important algorithmic concepts including references for further reading. As a practical example, details on a model-based iterative reconstruction algorithm implemented on a modern graphics adapter (GPU) are presented, followed by application examples for several dedicated CT scanners in order to demonstrate the performance and potential of iterative reconstruction methods. Finally, some general thoughts regarding the advantages and disadvantages of IR methods as well as open points for research in this field are discussed. PMID:22316498

  19. Automated lung segmentation of low resolution CT scans of rats

    NASA Astrophysics Data System (ADS)

    Rizzo, Benjamin M.; Haworth, Steven T.; Clough, Anne V.

    2014-03-01

    Dual modality micro-CT and SPECT imaging can play an important role in preclinical studies designed to investigate mechanisms, progression, and therapies for acute lung injury in rats. SPECT imaging involves examining the uptake of radiopharmaceuticals within the lung, with the hypothesis that uptake is sensitive to the health or disease status of the lung tissue. Methods of quantifying lung uptake and comparison of right and left lung uptake generally begin with identifying and segmenting the lung region within the 3D reconstructed SPECT volume. However, identification of the lung boundaries and the fissure between the left and right lung is not always possible from the SPECT images directly since the radiopharmaceutical may be taken up by other surrounding tissues. Thus, our SPECT protocol begins with a fast CT scan, the lung boundaries are identified from the CT volume, and the CT region is coregistered with the SPECT volume to obtain the SPECT lung region. Segmenting rat lungs within the CT volume is particularly challenging due to the relatively low resolution of the images and the rat's unique anatomy. Thus, we have developed an automated segmentation algorithm for low resolution micro-CT scans that utilizes depth maps to detect fissures on the surface of the lung volume. The fissure's surface location is in turn used to interpolate the fissure throughout the lung volume. Results indicate that the segmentation method results in left and right lung regions consistent with rat lung anatomy.

  20. Lingual mandibular bony defects: CT in the buccolingual plane

    SciTech Connect

    Slasky, B.S.; Bar-Ziv, J.

    1996-05-01

    Our goal was to record the appearance of lingular mandibular bony defects (LMBD) on CT imaging of the mandible in the buccolingual plane. During the CT evaluation of patients planning to undergo dental implant surgery, five cases of LMBD were found. Axial 1.2 x 1.00 mm overlapping CT sections of the mandible and the maxilla were obtained. Then with use of specific software (DentaCT; Elscint), panoramic and cross-sectional (buccolingual) images of the mandible and maxilla were reformatted. Five cases of posterior LMBD were identified; one patient had both a posterior as well as the much rarer anterior LMBD. All cases were incidental findings and all were asymptomatic. CT features of LMBD were displayed it axial, panoramic, and buccolingual planes. The characteristic opening of the bony defect in the lingual aspect of the mandible was clearly displayed on the axial as well as the buccolingual images; however, this key feature was not manifest on the panoramic images; however, this key feature was not manifest on the panoramic images of the mandible. CT features of LMBD in the buccolingual plane are added to the known radiologic description of this entity. 8 refs., 6 figs.

  1. Paranasal sinus surgery planning using CT virtual reality

    NASA Astrophysics Data System (ADS)

    Hopper, Kenneth D.

    2001-05-01

    CT virtual reality using volumetric rendering can tag such structures as the nasofrontal ducts, osteomeatal complexes, the middle turbinates, as well as the planned surgical sites in patients undergoing endoscopic surgery for inflammatory disease. Frequently, anatomical landmarks are obscured by overlying disease, making the endoscopic surgeon's job difficult. We have evaluated the use of CT virtual reality of the paranasal sinuses in assisting the surgeon in these types of cases. This paper reviews 25 patients with 40 sites with significant paranasal sinus disease in whom endoscopic surgery was planned. The ability of volumetric virtual reality with the various surgical sites chosen from the preoperative 2D CT's dramatically improved the accuracy of the endoscopic surgeon in localizing their surgical window. In the sphenoid sinus, the addition of CT endoscopy would have allowed the endoscopist to operate on the correct sinus an additional 28% of the time and help them miss vital structures in 25%. In the frontal sinus, CT endoscopy correctly directed the endoscopist to the correct sinus in an additional 44%. The results of this study indicate CT endoscopy may significantly improve the accuracy of endoscopic surgery into the frontal and sphenoid sinuses.

  2. Toward high-contrast breast CT at low radiation dose.

    PubMed

    Keyriläinen, Jani; Fernández, Manuel; Karjalainen-Lindsberg, Marja-Liisa; Virkkunen, Pekka; Leidenius, Marjut; von Smitten, Karl; Sipilä, Petri; Fiedler, Stefan; Suhonen, Heikki; Suortti, Pekka; Bravin, Alberto

    2008-10-01

    This study was approved by the local research ethics committee, and patient informed consent was obtained. The purpose of this study was to demonstrate that high-spatial-resolution low-dose analyzer-based x-ray computed tomography (CT) can substantially improve the radiographic contrast of breast tissue in vitro when compared with that attained by using diagnostic mammography and CT. An excised human breast tumor was examined by using analyzer-based x-ray imaging with synchrotron radiation. The correspondence between analyzer-based x-ray images and diagnostic mammograms, CT images, and histopathologic findings was determined. Calcifications and fine details of soft tissue, which are at the contrast detection limit on diagnostic mammograms, are clearly visible on planar analyzer-based x-ray images. Analyzer-based x-ray CT yields high contrast from smoothly varying internal structures, such as tumorous mass lesions, corresponding to information on actual structures seen at histopathologic analysis. The mean glandular dose of 1.9 mGy in analyzer-based x-ray CT is approximately equivalent to the dose administered during single-view screening mammography. The improved visibility of mammographically indistinguishable lesions in vitro suggests that analyzer-based x-ray CT may be a valuable method in radiographic evaluation of the breast, thereby justifying further investigations. PMID:18796684

  3. Utilization of CT images for the quantification of FDG uptake

    NASA Astrophysics Data System (ADS)

    Karidioula, I.; De Freitas, D.; Cachin, F.; Geissler, B.; Jullien, Ph.; Maublant, J.

    2006-12-01

    The aim of this study was to evaluate an automatic method based on a computed tomography (CT) derived region of interest (ROI) to quantify the mean standardized uptake value (SUVm) of 18F-fluoro-deoxy-glucose (FDG) in pulmonary lesions detected by positron emission tomography (PET). A total of 164 pairs of slices were selected in a series of PET/CT studies performed in 26 patients presenting lung tumours of various forms and complexities. On each matched CT slice, a ROI was obtained by growth-region segmentation starting from a pixel contained in the tumour. The obtained ROI was then applied to the PET image to calculate SUVm. Results were compared with the conventional manual method using a geometric ROI positioned directly on the PET lesion. The automatic delineation of the tumour from the CT image was successful in 136 sections (83%). The SUVm calculated by the manual and automatic method were respectively (mean±standard deviation) 5.05±2.39 and 6.70±3.18 ( p<0.05). The ROI size (in number of pixels) was respectively 28±23 and 21±17 ( p<0.05). The variability of the automatic method was 0% versus 20% for the manual method. SUV of FDG in PET/CT can be calculated with an excellent reproducibility by using the CT-derived limits of the lesion.

  4. CT Imaging Biomarkers Predict Clinical Outcomes After Pancreatic Cancer Surgery

    PubMed Central

    Zhu, Liang; Shi, Xiaohua; Xue, Huadan; Wu, Huanwen; Chen, Ge; Sun, Hao; He, Yonglan; Jin, Zhengyu; Liang, Zhiyong; Zhang, Zhuoli

    2016-01-01

    Abstract This study aimed to determine whether changes in contrast-enhanced computed tomography (CT) parameters could predict postsurgery overall and progression-free survival (PFS) in pancreatic cancer patients. Seventy-nine patients with a final pathological diagnosis of pancreatic adenocarcinoma were included in this study from June 2008 to August 2012. Dynamic contrast-enhanced (DCE) CT of tumors was obtained before curative-intent surgery. Absolute enhancement change (AEC) and relative enhancement change (REC) were evaluated on DCE-CT. PFS and overall survival (OS) were compared based on CT enhancement patterns. The markers of fibrogenic alpha-smooth muscle antigen (α-SMA) and periostin in tumor specimens were evaluated by immunohistochemical staining. The χ2 test was performed to determine whether CT enhancement patterns were associated with α-SMA-periostin expression levels (recorded as positive or negative). Lower REC (<0.9) was associated with shorter PFS (HR 0.51, 95% CI: 0.31–0.89) and OS (HR 0.44, 95% CI: 0.25–0.78). The α-SMA and periostin expression level were negatively correlated with REC (both P = 0). Among several CT enhancement parameters, REC was the best predictor of patient postsurgery survival. Low REC was associated with a short progression-free time and poor survival. The pathological studies suggested that REC might be a reflection of cancer fibrogenic potential. PMID:26844495

  5. Advances in optical CT scanning for gel dosimetry

    NASA Astrophysics Data System (ADS)

    Jordan, K.

    2004-01-01

    Optical computed tomography (CT) is physically similar to x-ray CT but is more versatile since many powerful light sources exist and optical elements such as mirrors, lenses, polarizers and efficient detectors are available. There are many potential forms of optical CT. Attenuation, fluorescence or scatter, polarization and refractive index spatial changes are all examples of optical CT. To date, optical CT for gel dosimetry has been limited to attenuation measurements that are the sum of scatter and absorption along defined lines. Polymerization gels turn white with absorbed dose and attenuation is due to scatter. Radiochromic gels also form a dose image due to changes in visible absorption. This short review concentrates on the papers published since the DOSGEL 2001 meeting and highlights experimental results and issues that are important for obtaining good quality input data for reconstruction. The format involves selected highlights from the papers and associated points from our experience with optical CT experimentation. The comments are intended to assist researchers unfamiliar with optical measurements to obtain high quality transmission data, a necessary step in quantitative gel dosimetry.

  6. WE-D-9A-02: Automated Landmark-Guided CT to Cone-Beam CT Deformable Image Registration

    SciTech Connect

    Kearney, V; Gu, X; Chen, S; Jiang, L; Liu, H; Chiu, T; Yordy, J; Nedzi, L; Mao, W

    2014-06-15

    Purpose: The anatomical changes that occur between the simulation CT and daily cone-beam CT (CBCT) are investigated using an automated landmark-guided deformable image registration (LDIR) algorithm with simultaneous intensity correction. LDIR was designed to be accurate in the presence of tissue intensity mismatch and heavy noise contamination. Method: An auto-landmark generation algorithm was used in conjunction with a local small volume (LSV) gradient matching search engine to map corresponding landmarks between the CBCT and planning CT. The LSVs offsets were used to perform an initial deformation, generate landmarks, and correct local intensity mismatch. The landmarks act as stabilizing controlpoints in the Demons objective function. The accuracy of the LDIR algorithm was evaluated on one synthetic case with ground truth and data of ten head and neck cancer patients. The deformation vector field (DVF) accuracy was accessed using a synthetic case. The Root mean square error of the 3D canny edge (RMSECE), mutual information (MI), and feature similarity index metric (FSIM) were used to access the accuracy of LDIR on the patient data. The quality of the corresponding deformed contours was verified by an attending physician. Results: The resulting 90 percentile DVF error for the synthetic case was within 5.63mm for the original demons algorithm, 2.84mm for intensity correction alone, 2.45mm using controlpoints without intensity correction, and 1.48 mm for the LDIR algorithm. For the five patients the mean RMSECE of the original CT, Demons deformed CT, intensity corrected Demons CT, control-point stabilized deformed CT, and LDIR CT was 0.24, 0.26, 0.20, 0.20, and 0.16 respectively. Conclusion: LDIR is accurate in the presence of multimodal intensity mismatch and CBCT noise contamination. Since LDIR is GPU based it can be implemented with minimal additional strain on clinical resources. This project has been supported by a CPRIT individual investigator award RP11032.

  7. Bilateral alien hand syndrome in cerebrovascular disease: CT, MR, CT angiography, and 99mTc-HMPAO-SPECT findings.

    PubMed

    Serrano-Vicente, Justo; Duran-Barquero, Carmen; Garcia-Bernardo, Lucia; Dominguez-Grande, Maria Luz; Infante-Torre, Jose Rafael; Rayo-Madrid, Juan Ignacio

    2015-03-01

    We report a 65-year-old man with a right cerebral infarction that occurred 15 years ago and a residual left hemiparesis that began with progressive contralateral hemiparesis. During the hospitalization, the patient developed a bilateral alien hand syndrome. Urgent CT, MR, CT angiography, and brain perfusion SPECT were performed that revealed an old right cerebral infarction and a new ischemic lesion in left parietal lobe and adjacent brain territories. PMID:25546190

  8. Pulmonary Intravascular Lymphomatosis: Clinical, CT, and PET Findings, Correlation of CT and Pathologic Results, and Survival Outcome.

    PubMed

    Cha, Min Jae; Lee, Kyung Soo; Hwang, Hye Sun; Kim, Tae Jung; Kim, Tae Sung; Kim, Byung-Tae; Ko, Young-Hyeh; Shim, Young Mog

    2016-08-01

    Purpose To describe clinical, computed tomographic (CT), and positron emission tomographic (PET) features, correlation of CT and pathologic results, and survival of patients with pulmonary intravascular lymphomatosis. Materials and Methods The institutional review board approved this retrospective study with waiver of patient consent. Forty-two patients with pulmonary intravascular lymphomatosis were identified, 11 (26%) of whom showed lung involvement. CT features were correlated with histopathologic results. Clinical and survival outcomes were compared between patients with and those without pulmonary involvement by adopting the χ(2), Student t, or Kaplan-Meier analysis with log-rank tests. Results At clinical presentation, all 11 patients showed B symptoms (systemic symptoms of fever, night sweats, and weight loss), 10 had respiratory and four had neurologic symptoms, and two had skin lesions. Patients received cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy with (n = 5) or without (n = 6) rituximab, and seven (64%) patients died. Patients with lung involvement showed reduced overall and recurrence-free survival (median; 10.8 and 18.9 months, respectively) compared with those without lung involvement (median, 18.4 and 31.0 months, respectively) (P = .338 and .065, respectively). The most common CT abnormality was bilateral ground-glass opacity (GGO, n = 10), with increased fluorodeoxyglucose uptake at PET/CT (seven of seven patients). GGO correlated histopathologically with the expanded alveolar septal vasculatures and perivascular spaces filled with neoplastic lymphoid cells. Conclusion Pulmonary intravascular lymphomatosis appeared as bilateral GGO on CT images, with increased fluorodeoxyglucose uptake on PET/CT images. GGO on CT images correlated with the area of expanded alveolar septae because of distended vessels filled with neoplastic lymphoid cells. (©) RSNA, 2016 Online supplemental material is available for this article. PMID

  9. Intense uptake evidenced by 18F-FDG PET/CT without a corresponding CT finding--dream or reality?

    PubMed

    Caobelli, Federico; Pizzocaro, Claudio; Guerra, Ugo Paolo

    2014-01-01

    Although 18F-fluoro-deoxy-glucose (FDG) positron emission tomography (PET) has been widely validated and extensively used in the latest years in clinical practice, interpretation of PET/CT images can be affected by several pitfalls. We here present a case of intense lung uptake in a patient without a corresponding finding on CT images, probably due to a microembolism produced during the injection process and located in small vascular structures of the lung parenchyma. PMID:24610649

  10. Optimization of SPECT-CT Hybrid Imaging Using Iterative Image Reconstruction for Low-Dose CT: A Phantom Study

    PubMed Central

    Grosser, Oliver S.; Kupitz, Dennis; Ruf, Juri; Czuczwara, Damian; Steffen, Ingo G.; Furth, Christian; Thormann, Markus; Loewenthal, David; Ricke, Jens; Amthauer, Holger

    2015-01-01

    Background Hybrid imaging combines nuclear medicine imaging such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) with computed tomography (CT). Through this hybrid design, scanned patients accumulate radiation exposure from both applications. Imaging modalities have been the subject of long-term optimization efforts, focusing on diagnostic applications. It was the aim of this study to investigate the influence of an iterative CT image reconstruction algorithm (ASIR) on the image quality of the low-dose CT images. Methodology/Principal Findings Examinations were performed with a SPECT-CT scanner with standardized CT and SPECT-phantom geometries and CT protocols with systematically reduced X-ray tube currents. Analyses included image quality with respect to photon flux. Results were compared to the standard FBP reconstructed images. The general impact of the CT-based attenuation maps used during SPECT reconstruction was examined for two SPECT phantoms. Using ASIR for image reconstructions, image noise was reduced compared to FBP reconstructions for the same X-ray tube current. The Hounsfield unit (HU) values reconstructed by ASIR were correlated to the FBP HU values(R2 ≥ 0.88) and the contrast-to-noise ratio (CNR) was improved by ASIR. However, for a phantom with increased attenuation, the HU values shifted for low X-ray tube currents I ≤ 60 mA (p ≤ 0.04). In addition, the shift of the HU values was observed within the attenuation corrected SPECT images for very low X-ray tube currents (I ≤ 20 mA, p ≤ 0.001). Conclusion/Significance In general, the decrease in X-ray tube current up to 30 mA in combination with ASIR led to a reduction of CT-related radiation exposure without a significant decrease in image quality. PMID:26390216

  11. A dedicated micro-CT beamline for the Australian Synchrotron and the Remote-CT project

    NASA Astrophysics Data System (ADS)

    Mayo, S. C.; Gureyev, T. E.; Nesterets, Y. I.; Thompson, D. A.; Siu, K. K. W.; Wallwork, K.

    2013-10-01

    A dedicated micro-CT beamline is planned for the Australian Synchrotron which will extend the synchrotron's imaging and tomography capability down to the smaller scale, incorporating phase-contrast and absorption-contrast, and an additional focussing-based mode for high-resolution. The beamline will use multi-layer mirror monochromators for enhanced flux, and will focus particularly on dynamic and high throughput studies in both monochromatic and pink-beam mode. Together with the existing Imaging and Medical beamline, this beamline will produce numerous large datasets of 10 GB or more, providing a significant data-processing challenge. The Remote-CT project addresses this by combining the "MASSIVE" supercomputing GPU cluster with XLI / X-TRACT software, developed at CSIRO. This software has extensive functionality for both processing and simulation of absorption and phase-contrast tomography data and has now been modified for parallel operation on a GPU cluster to take maximum advantage of the speed-up this enables.

  12. Compensation of mechanical inaccuracies in micro-CT and nano-CT

    NASA Astrophysics Data System (ADS)

    Sasov, Alexander; Liu, Xuan; Salmon, Phil L.

    2008-08-01

    Micro-CT and especially nano-CT scanning requires very high mechanical precision and stability of object manipulator, which is difficult to reach. Several other problems, such as drift of emission point inside an X-ray source, thermal expansion in different parts of the scanner, mechanical vibrations, and object movement or shrinkage during long scans, can also contribute to geometrical inaccuracies. All these inaccuracies result in artifacts which reduce achievable spatial resolution. Linear distortions can be partially compensated by rigid X/Y shifts in projection images. More complicated object movement and shrinkage will require non-linear transforms. This paper investigates techniques to compensate geometrical inaccuracies by linear transformation only. We have developed two methods to estimate individual X/Y shifts in each measured projection. The first method aligns measured projections with forward-projected projections iteratively to reach an optimal X/Y shift estimation. It is more suitable for mechanical inaccuracies caused by random and jittery movement. The second method uses a very short reference scan acquired immediately after a main scan to obtain estimates of X/Y shifts. This method is rather effective for mechanical inaccuracies caused by slow and coherent mechanical drifts. Both methods have been implemented and evaluated on multiple scanners. Significant improvements in image quality have been observed.

  13. CT reconstruction techniques for improved accuracy of lung CT airway measurement

    SciTech Connect

    Rodriguez, A.; Ranallo, F. N.; Judy, P. F.; Gierada, D. S.; Fain, S. B.

    2014-11-01

    Purpose: To determine the impact of constrained reconstruction techniques on quantitative CT (qCT) of the lung parenchyma and airways for low x-ray radiation dose. Methods: Measurement of small airways with qCT remains a challenge, especially for low x-ray dose protocols. Images of the COPDGene quality assurance phantom (CTP698, The Phantom Laboratory, Salem, NY) were obtained using a GE discovery CT750 HD scanner for helical scans at x-ray radiation dose-equivalents ranging from 1 to 4.12 mSv (12–100 mA s current–time product). Other parameters were 40 mm collimation, 0.984 pitch, 0.5 s rotation, and 0.625 mm thickness. The phantom was sandwiched between 7.5 cm thick water attenuating phantoms for a total length of 20 cm to better simulate the scatter conditions of patient scans. Image data sets were reconstructed using STANDARD (STD), DETAIL, BONE, and EDGE algorithms for filtered back projection (FBP), 100% adaptive statistical iterative reconstruction (ASIR), and Veo reconstructions. Reduced (half) display field of view (DFOV) was used to increase sampling across airway phantom structures. Inner diameter (ID), wall area percent (WA%), and wall thickness (WT) measurements of eight airway mimicking tubes in the phantom, including a 2.5 mm ID (42.6 WA%, 0.4 mm WT), 3 mm ID (49.0 WA%, 0.6 mm WT), and 6 mm ID (49.0 WA%, 1.2 mm WT) were performed with Airway Inspector (Surgical Planning Laboratory, Brigham and Women’s Hospital, Boston, MA) using the phase congruency edge detection method. The average of individual measures at five central slices of the phantom was taken to reduce measurement error. Results: WA% measures were greatly overestimated while IDs were underestimated for the smaller airways, especially for reconstructions at full DFOV (36 cm) using the STD kernel, due to poor sampling and spatial resolution (0.7 mm pixel size). Despite low radiation dose, the ID of the 6 mm ID airway was consistently measured accurately for all methods other than STD

  14. Development of CT and 3D-CT Using Flat Panel Detector Based Real-Time Digital Radiography System

    SciTech Connect

    Ravindran, V. R.; Sreelakshmi, C.; Vibin

    2008-09-26

    The application of Digital Radiography in the Nondestructive Evaluation (NDE) of space vehicle components is a recent development in India. A Real-time DR system based on amorphous silicon Flat Panel Detector has been developed for the NDE of solid rocket motors at Rocket Propellant Plant of VSSC in a few years back. The technique has been successfully established for the nondestructive evaluation of solid rocket motors. The DR images recorded for a few solid rocket specimens are presented in the paper. The Real-time DR system is capable of generating sufficient digital X-ray image data with object rotation for the CT image reconstruction. In this paper the indigenous development of CT imaging based on the Realtime DR system for solid rocket motor is presented. Studies are also carried out to generate 3D-CT image from a set of adjacent CT images of the rocket motor. The capability of revealing the spatial location and characterisation of defect is demonstrated by the CT and 3D-CT images generated.

  15. Imaging lobular breast carcinoma: comparison of synchrotron radiation DEI-CT technique with clinical CT, mammography and histology

    NASA Astrophysics Data System (ADS)

    Fiedler, S.; Bravin, A.; Keyriläinen, J.; Fernández, M.; Suortti, P.; Thomlinson, W.; Tenhunen, M.; Virkkunen, P.; Karjalainen-Lindsberg, M.-L.

    2004-01-01

    Different modalities for imaging cancer-bearing breast tissue samples are described and compared. The images include clinical mammograms and computed tomography (CT) images, CT images with partly coherent synchrotron radiation (SR), and CT and radiography images taken with SR using the diffraction enhanced imaging (DEI) method. The images are evaluated by a radiologist and compared with histopathological examination of the samples. Two cases of lobular carcinoma are studied in detail. The indications of cancer are very weak or invisible in the conventional images, but the morphological changes due to invasion of cancer become pronounced in the images taken by the DEI method. The strands penetrating adipose tissue are seen clearly in the DEI-CT images, and the histopathology confirms that some strands contain the so-called 'Indian file' formations of cancer cells. The radiation dose is carefully measured for each of the imaging modalities. The mean glandular dose (MGD) for 50% glandular breast tissue is about 1 mGy in conventional mammography and less than 0.25 mGy in projection DEI, while in the clinical CT imaging the MGD is very high, about 45 mGy. The entrance dose of 95 mGy in DEI-CT imaging gives rise to an MGD of 40 mGy, but the dose may be reduced by an order of magnitude, because the contrast is very large in most images.

  16. Human airway measurement from CT images

    NASA Astrophysics Data System (ADS)

    Lee, Jaesung; Reeves, Anthony P.; Fotin, Sergei; Apanasovich, Tatiyana; Yankelevitz, David

    2008-03-01

    A wide range of pulmonary diseases, including common ones such as COPD, affect the airways. If the dimensions of airway can be measured with high confidence, the clinicians will be able to better diagnose diseases as well as monitor progression and response to treatment. In this paper, we introduce a method to assess the airway dimensions from CT scans, including the airway segments that are not oriented axially. First, the airway lumen is segmented and skeletonized, and subsequently each airway segment is identified. We then represent each airway segment using a segment-centric generalized cylinder model and assess airway lumen diameter (LD) and wall thickness (WT) for each segment by determining inner and outer wall boundaries. The method was evaluated on 14 healthy patients from a Weill Cornell database who had two scans within a 2 month interval. The corresponding airway segments were located in two scans and measured using the automated method. The total number of segments identified in both scans was 131. When 131 segments were considered altogether, the average absolute change over two scans was 0.31 mm for LD and 0.12 mm for WT, with 95% limits of agreement of [-0.85, 0.83] for LD and [-0.32, 0.26] for WT. The results were also analyzed on per-patient basis, and the average absolute change was 0.19 mm for LD and 0.05 mm for WT. 95% limits of agreement for per-patient changes were [-0.57, 0.47] for LD and [-0.16, 0.10] for WT.

  17. Rodent brain imaging with SPECT/CT

    SciTech Connect

    Seo, Youngho; Gao, D.-W.; Hasegawa, Bruce H.; Dae, Michael W.; Franc, Benjamin L.

    2007-04-15

    We evaluated methods of imaging rat models of stroke in vivo using a single photon emission computed tomography (SPECT) system dedicated to small animal imaging (X-SPECT{sup TM}, Gamma Medica-Ideas, Northridge, CA). An animal model of ischemic stroke was developed for in vivo SPECT/CT imaging using the middle cerebral artery occlusion (MCAO) technique. The presence of cerebral ischemia was verified in ex vivo studies using triphenyltetrazolium chloride (TTC) staining. In vivo radionuclide imaging of cerebral blood flow was performed in rats following MCAO using dynamic planar imaging of {sup 99m}Tc-exametazime with parallel hole collimation. This was followed immediately by in vivo radionuclide imaging of cerebral blood flow with {sup 99m}Tc-exametazime in the same animals using 1-mm pinhole SPECT. Correlated computed tomography imaging was performed to localize radiopharmaceutical uptake. The animals were allowed to recover and ex vivo autoradiography was performed with separate administration of {sup 99m}Tc-exametazime. Time activity curve of {sup 99m}Tc-exametazime showed that the radiopharmaceutical uptake could be maintained for over 9 min. The activity would be expected to be relatively stable for a much longer period, although the data were only obtained for 9 min. TTC staining revealed sizable infarcts by visual observation of inexistence of TTC stain in infracted tissues of MCAO rat brains. In vivo SPECT imaging showed cerebral blood flow deficit in the MCAO model, and the in vivo imaging result was confirmed with ex vivo autoradiography. We have demonstrated a capability of imaging regions of cerebral blood flow deficit in MCAO rat brains in vivo using a pinhole SPECT dedicated to small animal imaging.

  18. CoNNeCT Baseband Processor Module

    NASA Technical Reports Server (NTRS)

    Yamamoto, Clifford K; Jedrey, Thomas C.; Gutrich, Daniel G.; Goodpasture, Richard L.

    2011-01-01

    A document describes the CoNNeCT Baseband Processor Module (BPM) based on an updated processor, memory technology, and field-programmable gate arrays (FPGAs). The BPM was developed from a requirement to provide sufficient computing power and memory storage to conduct experiments for a Software Defined Radio (SDR) to be implemented. The flight SDR uses the AT697 SPARC processor with on-chip data and instruction cache. The non-volatile memory has been increased from a 20-Mbit EEPROM (electrically erasable programmable read only memory) to a 4-Gbit Flash, managed by the RTAX2000 Housekeeper, allowing more programs and FPGA bit-files to be stored. The volatile memory has been increased from a 20-Mbit SRAM (static random access memory) to a 1.25-Gbit SDRAM (synchronous dynamic random access memory), providing additional memory space for more complex operating systems and programs to be executed on the SPARC. All memory is EDAC (error detection and correction) protected, while the SPARC processor implements fault protection via TMR (triple modular redundancy) architecture. Further capability over prior BPM designs includes the addition of a second FPGA to implement features beyond the resources of a single FPGA. Both FPGAs are implemented with Xilinx Virtex-II and are interconnected by a 96-bit bus to facilitate data exchange. Dedicated 1.25- Gbit SDRAMs are wired to each Xilinx FPGA to accommodate high rate data buffering for SDR applications as well as independent SpaceWire interfaces. The RTAX2000 manages scrub and configuration of each Xilinx.

  19. Radiochromic films for dental CT dosimetry: a feasibility study.

    PubMed

    Rampado, O; Bianchi, S D; Peruzzo Cornetto, A; Rossetti, V; Ropolo, R

    2014-02-01

    Dental CT dose evaluations are commonly performed using thermoluminescent dosimeters (TLD) inside anthropomorphic phantoms. Radiochromic films with good sensitivity in the X-ray diagnostic field have recently been developed and are commercially available as GAFCHROMIC XR-QA. There are potential advantages in the use of radiochromic films such as a more comprehensive dosimetry thanks to the adjustable size of the film samples. The purpose of this study was to investigate the feasibility of using radiochromic films for dental CT dose evaluations. Film samples were cut with a width of 5mm and a length of 25 mm (strips), the same size as the Alderson Rando anthropomorphic phantom holes used in this study. Dental CT dose measurements were performed using simultaneously both TLD and radiochromic strips in the same phantom sites. Two equipment types were considered for dental CT examinations: a 16 slice CT and a cone beam CT. Organ equivalent doses were then obtained averaging the measurements from the sites of the same organ and effective doses were calculated using ICRP 103 weighting factors. The entire procedure was repeated four times for each CT in order to compare also the repeatability of the two dosimeter types. A linear correlation was found between the absorbed dose evaluated with radiochromic films and with TLD, with slopes of 0.930 and 0.944 (correlation r>0.99). The maximum difference between the two dosimeter's measurements was 25%, whereas the average difference was 7%. The measurement repeatability was comparable for the two dosimeters at cumulative doses above 15 mGy (estimated uncertainty at 1 sigma level of about 5%), whereas below this threshold radiochromic films show a greater dispersion of data, of about 10% at 1 sigma level. We obtained, using respectively Gafchromic and TLD measurements, effective dose values of 107 μSv and 117 μSv (i.e. difference of 8.6%) for the cone beam CT and of 523 μSv and 562 μSv (i.e. difference of 7%) for the

  20. 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

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

    PubMed

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

    2015-10-01

    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

  2. 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

  3. Phantom based evaluation of CT to CBCT image registration for proton therapy dose recalculation

    NASA Astrophysics Data System (ADS)

    Landry, Guillaume; Dedes, George; Zöllner, Christoph; Handrack, Josefine; Janssens, Guillaume; Orban de Xivry, Jonathan; Reiner, Michael; Paganelli, Chiara; Riboldi, Marco; Kamp, Florian; Söhn, Matthias; Wilkens, Jan J.; Baroni, Guido; Belka, Claus; Parodi, Katia

    2015-01-01

    The ability to perform dose recalculation on the anatomy of the day is important in the context of adaptive proton therapy. The objective of this study was to investigate the use of deformable image registration (DIR) and cone beam CT (CBCT) imaging to generate the daily stopping power distribution of the patient. We investigated the deformation of the planning CT scan (pCT) onto daily CBCT images to generate a virtual CT (vCT) using a deformable phantom designed for the head and neck (H & N) region. The phantom was imaged at a planning CT scanner in planning configuration, yielding a pCT and in deformed, treatment day configuration, yielding a reference CT (refCT). The treatment day configuration was additionally scanned at a CBCT scanner. A Morphons DIR algorithm was used to generate a vCT. The accuracy of the vCT was evaluated by comparison to the refCT in terms of corresponding features as identified by an adaptive scale invariant feature transform (aSIFT) algorithm. Additionally, the vCT CT numbers were compared to those of the refCT using both profiles and regions of interest and the volumes and overlap (DICE coefficients) of various phantom structures were compared. The water equivalent thickness (WET) of the vCT, refCT and pCT were also compared to evaluate proton range differences. Proton dose distributions from the same initial fluence were calculated on the refCT, vCT and pCT and compared in terms of proton range. The method was tested on a clinical dataset using a replanning CT scan acquired close in time to a CBCT scan as reference using the WET evaluation. Results from the aSIFT investigation suggest a deformation accuracy of 2-3 mm. The use of the Morphon algorithm did not distort CT number intensity in uniform regions and WET differences between vCT and refCT were of the order of 2% of the proton range. This result was confirmed by proton dose calculations. The patient results were consistent with phantom observations. In conclusion, our phantom

  4. Ring artifacts removal from synchrotron CT image slices

    NASA Astrophysics Data System (ADS)

    Wei, Zhouping; Wiebe, Sheldon; Chapman, Dean

    2013-06-01

    Ring artifacts can occur in reconstructed images from x-ray Computerized Tomography (CT) as full or partial concentric rings superimposed on the scanned structures. Due to the data corruption by those ring artifacts in CT images, qualitative and quantitative analysis of these images are compromised. In this paper, we propose to correct the ring artifacts on the reconstructed synchrotron radiation (SR) CT image slices. The proposed correction procedure includes the following steps: (1). transform the reconstructed CT images into polar coordinates; (2) apply discrete two-dimensional (2D) wavelet transform to the polar image to decompose it into four image components: low pass band image component, as well as the components from horizontal, vertical and diagonal details bands; (3). apply 2D Fourier transform to the vertical details band image component only, since the ring artifacts become vertical lines in the polar coordinates; (4). apply Gaussian filtering in Fourier domain along the abscissa direction to suppress the vertical lines, since the information of the vertical lines in Fourier domain is completely condensed to that direction; (5). perform inverse Fourier transform to get the corrected vertical details band image component; (6). perform inverse wavelet transform to get the corrected polar image; (7). transform the corrected polar image back to Cartesian coordinates to get the CT image slice with reduced ring artifacts. This approach has been successfully used on CT data acquired from the Biomedical Imaging and Therapy (BMIT) beamline in Canadian Light Source (CLS), and the results show that the ring artifacts in original SR CT images have been effectively suppressed with all the structure information in the image preserved.

  5. Dual-Energy Spectral CT: Various Clinical Vascular Applications.

    PubMed

    Machida, Haruhiko; Tanaka, Isao; Fukui, Rika; Shen, Yun; Ishikawa, Takuya; Tate, Etsuko; Ueno, Eiko

    2016-01-01

    Single-source dual-energy (DE) computed tomography (CT) with fast switching of tube voltage allows projection-based image reconstruction, substantial reduction of beam-hardening effects, reconstruction of accurate monochromatic images and material decomposition images (MDIs), and detailing of material composition by using x-ray spectral information. In vascular applications, DE CT is expected to overcome limitations of standard single-energy CT angiography, including patient exposure to nephrotoxic contrast medium and carcinogenic radiation, insufficient contrast vascular enhancement, interference from metallic and beam-hardening artifacts and severe vessel calcification, and limited tissue characterization and perfusion assessment. Acquisition of low-energy monochromatic images and iodine/water MDIs can reasonably reduce contrast agent dose and improve vessel enhancement. Acquisition of virtual noncontrast images, such as water/iodine MDIs, can reduce overall radiation exposure by replacing true noncontrast CT in each examination. Acquisition of monochromatic images by using metal artifact reduction software or acquisition of iodine/water MDIs can reduce metal artifacts with preserved or increased vessel contrast, and subtraction of monochromatic images between two energy levels can subtract coils composed of dense metallic materials. Acquisition of iodine/calcium (ie, hydroxyapatite) MDIs permits subtraction of vessel calcification and improves vessel lumen delineation. Sensitive detection of lipid-rich plaque can be achieved by using fat/water MDIs, the spectral Hounsfield unit curve (energy level vs CT attenuation), and a histogram of effective atomic numbers included in an image. Various MDIs are useful for accurate differentiation among materials with high attenuation values, including contrast medium, calcification, and fresh hematoma. Iodine/water MDIs are used to assess organ perfusion, such as in the lungs and myocardium. Understanding these DE CT

  6. Surface-based registration of liver in ultrasound and CT

    NASA Astrophysics Data System (ADS)

    Dehghan, Ehsan; Lu, Kongkuo; Yan, Pingkun; Tahmasebi, Amir; Xu, Sheng; Wood, Bradford J.; Abi-Jaoudeh, Nadine; Venkatesan, Aradhana; Kruecker, Jochen

    2015-03-01

    Ultrasound imaging is an attractive modality for real-time image-guided interventions. Fusion of US imaging with a diagnostic imaging modality such as CT shows great potential in minimally invasive applications such as liver biopsy and ablation. However, significantly different representation of liver in US and CT turns this image fusion into a challenging task, in particular if some of the CT scans may be obtained without contrast agents. The liver surface, including the diaphragm immediately adjacent to it, typically appears as a hyper-echoic region in the ultrasound image if the proper imaging window and depth setting are used. The liver surface is also well visualized in both contrast and non-contrast CT scans, thus making the diaphragm or liver surface one of the few attractive common features for registration of US and non-contrast CT. We propose a fusion method based on point-to-volume registration of liver surface segmented in CT to a processed electromagnetically (EM) tracked US volume. In this approach, first, the US image is pre-processed in order to enhance the liver surface features. In addition, non-imaging information from the EM-tracking system is used to initialize and constrain the registration process. We tested our algorithm in comparison with a manually corrected vessel-based registration method using 8 pairs of tracked US and contrast CT volumes. The registration method was able to achieve an average deviation of 12.8mm from the ground truth measured as the root mean square Euclidean distance for control points distributed throughout the US volume. Our results show that if the US image acquisition is optimized for imaging of the diaphragm, high registration success rates are achievable.

  7. Interior micro-CT with an offset detector

    SciTech Connect

    Sharma, Kriti Sen; Gong, Hao; Ghasemalizadeh, Omid; Yu, Hengyong; Wang, Ge

    2014-06-15

    Purpose: The size of field-of-view (FOV) of a microcomputed tomography (CT) system can be increased by offsetting the detector. The increased FOV is beneficial in many applications. All prior investigations, however, have been focused to the case in which the increased FOV after offset-detector acquisition can cover the transaxial extent of an object fully. Here, the authors studied a new problem where the FOV of a micro-CT system, although increased after offset-detector acquisition, still covers an interior region-of-interest (ROI) within the object. Methods: An interior-ROI-oriented micro-CT scan with an offset detector poses a difficult reconstruction problem, which is caused by both detector offset and projection truncation. Using the projection completion techniques, the authors first extended three previous reconstruction methods from offset-detector micro-CT to offset-detector interior micro-CT. The authors then proposed a novel method which combines two of the extended methods using a frequency split technique. The authors tested the four methods with phantom simulations at 9.4%, 18.8%, 28.2%, and 37.6% detector offset. The authors also applied these methods to physical phantom datasets acquired at the same amounts of detector offset from a customized micro-CT system. Results: When the detector offset was small, all reconstruction methods showed good image quality. At large detector offset, the three extended methods gave either visible shading artifacts or high deviation of pixel value, while the authors’ proposed method demonstrated no visible artifacts and minimal deviation of pixel value in both the numerical simulations and physical experiments. Conclusions: For an interior micro-CT with an offset detector, the three extended reconstruction methods can perform well at a small detector offset but show strong artifacts at a large detector offset. When the detector offset is large, the authors’ proposed reconstruction method can outperform the three

  8. Cerebellar Transcranial Direct Current Stimulation (ctDCS)

    PubMed Central

    Grimaldi, Giuliana; Argyropoulos, Georgios P.; Bastian, Amy; Cortes, Mar; Davis, Nicholas J.; Edwards, Dylan J.; Ferrucci, Roberta; Fregni, Felipe; Galea, Joseph M.; Hamada, Masahi; Manto, Mario; Miall, R. Chris; Morales-Quezada, Leon; Pope, Paul A.; Priori, Alberto; Rothwell, John; Tomlinson, S. Paul; Celnik, Pablo

    2016-01-01

    The cerebellum is critical for both motor and cognitive control. Dysfunction of the cerebellum is a component of multiple neurological disorders. In recent years, interventions have been developed that aim to excite or inhibit the activity and function of the human cerebellum. Transcranial direct current stimulation of the cerebellum (ctDCS) promises to be a powerful tool for the modulation of cerebellar excitability. This technique has gained popularity in recent years as it can be used to investigate human cerebellar function, is easily delivered, is well tolerated, and has not shown serious adverse effects. Importantly, the ability of ctDCS to modify behavior makes it an interesting approach with a potential therapeutic role for neurological patients. Through both electrical and non-electrical effects (vascular, metabolic) ctDCS is thought to modify the activity of the cerebellum and alter the output from cerebellar nuclei. Physiological studies have shown a polarity-specific effect on the modulation of cerebellar–motor cortex connectivity, likely via cerebellar–thalamocortical pathways. Modeling studies that have assessed commonly used electrode montages have shown that the ctDCS-generated electric field reaches the human cerebellum with little diffusion to neighboring structures. The posterior and inferior parts of the cerebellum (i.e., lobules VI-VIII) seem particularly susceptible to modulation by ctDCS. Numerous studies have shown to date that ctDCS can modulate motor learning, and affect cognitive and emotional processes. Importantly, this intervention has a good safety profile; similar to when applied over cerebral areas. Thus, investigations have begun exploring ctDCS as a viable intervention for patients with neurological conditions. PMID:25406224

  9. Fusion of PET and CT images using wavelet transform.

    PubMed

    Shalchian, Bahareh; Rajabi, Hossein; Soltanian-zadeh, Hamid

    2009-01-01

    While information about anatomy is available in CT images, information about physiology and metabolism is available in PET images. To integrate both information, the two images are fused. Image fusion methods include simple methods like pixel averaging and sophisticated methods like wavelet transformation. An advantage of using wavelet transformation is that it preserves significant parts of each image. After creating lesions of 10, 8, 6 mm in a NURBS (non-uniform rational B-splines) based cardiac torso (NCAT) phantom, PET images were simulated using SimSET simulator. Attenuation maps of the activity phantom were used as CT images. Each of the PET and CT images was divided into an approximation image and three detailed images by the wavelet transform. The corresponding transformed images generated from the PET and CT images were fused in nine different ways to generate composite images, which were compared to the original images. The basis of comparison is the lesion-to-tissue contrast in the fused image in comparison to the lesion-to-tissue contrast in the original PET and CT images. Our results showed that except for one method, the lesion-to-tissue contrast in the fused image was higher than that of the CT images. In the first six methods, the lesion-to-tissue contrast in the fused image was less than the contrast, in the PET image. In the other three methods, the contrast in the fused image was higher than in the PET image. This was true in cases of 10, 8, 6 mm lesions. In conclusion, we have show that the approximation image produced a better ultimate image and that the lesion-to-tissue contrast in the fused image was also better than that of the original PET and CT images. This is because the approximation image is comprised of fundamental information of the signal (low frequency) that directly affects the image contrast. PMID:19936335

  10. Simulation of four-dimensional CT images from deformable registration between inhale and exhale breath-hold CT scans

    SciTech Connect

    Sarrut, David; Boldea, Vlad; Miguet, Serge; Ginestet, Chantal

    2006-03-15

    Purpose: We propose to simulate an artificial four-dimensional (4-D) CT image of the thorax during breathing. It is performed by deformable registration of two CT scans acquired at inhale and exhale breath-hold. Materials and methods: Breath-hold images were acquired with the ABC (Active Breathing Coordinator) system. Dense deformable registrations were performed. The method was a minimization of the sum of squared differences (SSD) using an approximated second-order gradient. Gaussian and linear-elastic vector field regularizations were compared. A new preprocessing step, called a priori lung density modification (APLDM), was proposed to take into account lung density changes due to inspiration. It consisted of modulating the lung densities in one image according to the densities in the other, in order to make them comparable. Simulated 4-D images were then built by vector field interpolation and image resampling of the two initial CT images. A variation in the lung density was taken into account to generate intermediate artificial CT images. The Jacobian of the deformation was used to compute voxel values in Hounsfield units. The accuracy of the deformable registration was assessed by the spatial correspondence of anatomic landmarks located by experts. Results: APLDM produced statistically significantly better results than the reference method (registration without APLDM preprocessing). The mean (and standard deviation) of distances between automatically found landmark positions and landmarks set by experts were 2.7(1.1) mm with APLDM, and 6.3(3.8) mm without. Interexpert variability was 2.3(1.2) mm. The differences between Gaussian and linear elastic regularizations were not statistically significant. In the second experiment using 4-D images, the mean difference between automatic and manual landmark positions for intermediate CT images was 2.6(2.0) mm. Conclusion: The generation of 4-D CT images by deformable registration of inhale and exhale CT images is

  11. An assessment of image distortion and CT number accuracy within a wide-bore CT extended field of view.

    PubMed

    Beeksma, B; Truant, D; Holloway, L; Arumugam, S

    2015-06-01

    Although wide bore computed tomography (CT) scanners provide increased space for patients, the scan field of view (sFOV) remains considerably smaller than the bore size. Consequently, patient anatomy which spans beyond the sFOV is truncated and the information is lost. As a solution, some manufacturers provide the capacity to reconstruct CT images from a partial dataset at an extended field of view (eFOV). To assess spatial distortion within this eFOV three phantoms were considered a 30 × 30 × 20 cm(3) slab of solid water, the Gammex electron density CT phantom and a female anthropomorphic phantom. For each phantom, scans were taken centrally within the sFOV as a reference image and with the phantom edge extended at 1 cm intervals from 0 to 5 cm beyond the sFOV into the eFOV. To assess CT number accuracy various tissue equivalent materials were scanned in the eFOV and resulting CT numbers were compared to inserts scanned within the sFOV. For all phantom geometries, objects within the eFOV were geometrically overestimated with elongation of phantom shapes into the eFOV. The percentage increase in size ranged from 0.22 to 15.94 % over all phantoms considered. The difference between eFOV and sFOV CT numbers was dependent upon insert density. The eFOV underestimated CT numbers in the range of -127 to -230 HU for soft tissue densities and -278 to -640 for bone densities. This trend reversed for low tissue densities with the CT numbers in the eFOV being overestimated by 100-130 HU for lung equivalent inserts. Initial correlation between eFOV and sFOV CT numbers was seen and a correction function was successfully applied to better estimate the CT number representative of that seen within the sFOV. PMID:26048719

  12. Measurement of time delay for a prospectively gated CT simulator.

    PubMed

    Goharian, M; Khan, R F H

    2010-04-01

    For the management of mobile tumors, respiratory gating is the ideal option, both during imaging and during therapy. The major advantage of respiratory gating during imaging is that it is possible to create a single artifact-free CT data-set during a selected phase of the patient's breathing cycle. The purpose of the present work is to present a simple technique to measure the time delay during acquisition of a prospectively gated CT. The time delay of a Philips Brilliance BigBore (Philips Medical Systems, Madison, WI) scanner attached to a Varian Real-Time Position Management (RPM) system (Varian Medical Systems, Palo Alto, CA) was measured. Two methods were used to measure the CT time delay: using a motion phantom and using a recorded data file from the RPM system. In the first technique, a rotating wheel phantom was altered by placing two plastic balls on its axis and rim, respectively. For a desired gate, the relative positions of the balls were measured from the acquired CT data and converted into corresponding phases. Phase difference was calculated between the measured phases and the desired phases. Using period of motion, the phase difference was converted into time delay. The Varian RPM system provides an external breathing signal; it also records transistor-transistor logic (TTL) 'X-Ray ON' status signal from the CT scanner in a text file. The TTL 'X-Ray ON' indicates the start of CT image acquisition. Thus, knowledge of the start time of CT acquisition, combined with the real-time phase and amplitude data from the external respiratory signal, provides time-stamping of all images in an axial CT scan. The TTL signal with time-stamp was used to calculate when (during the breathing cycle) a slice was recorded. Using the two approaches, the time delay between the prospective gating signal and CT simulator has been determined to be 367 +/- 40 ms. The delay requires corrections both at image acquisition and while setting gates for the treatment delivery

  13. Characterization of the nanoDot OSLD dosimeter in CT

    PubMed Central

    Scarboro, Sarah B.; Cody, Dianna; Alvarez, Paola; Followill, David; Court, Laurence; Stingo, Francesco C.; Zhang, Di; Kry, Stephen F.

    2015-01-01

    Purpose: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. Methods: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80–140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Results: Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Conclusions: Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly effects due

  14. Characterization of the nanoDot OSLD dosimeter in CT

    SciTech Connect

    Scarboro, Sarah B.; Cody, Dianna; Followill, David; Court, Laurence; Stingo, Francesco C.; Kry, Stephen F.; Alvarez, Paola; Zhang, Di; McNitt-Gray, Michael

    2015-04-15

    Purpose: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. Methods: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80–140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Results: Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Conclusions: Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly effects due

  15. CT manifestations of adrenal trauma: experience with 73 cases.

    PubMed

    Sinelnikov, Alex O; Abujudeh, Hani H; Chan, David; Novelline, Robert A

    2007-03-01

    Adrenal injuries, although an uncommon consequence of abdominal trauma, are important to recognize. If bilateral, adrenal trauma could result in life-threatening adrenal insufficiency. Furthermore, in the setting of trauma, adrenal injury can point to other concomitant injuries and has been associated with overall increased morbidity and mortality. In the past, before the advent of computed tomography (CT), detection was difficult, and the diagnosis was often made only at surgery or postmortem. Today, the diagnosis of adrenal injuries can be quickly and accurately made with CT. This retrospective review was carried out to identify, describe, and analyze different CT appearances of adrenal injuries and correlated with associated injuries and observed clinical context and outcomes. A patient cohort of CT-detected adrenal injuries was identified through a radiology software research tool by searching for keywords in radiology reports. The identified CT scans were reviewed and correlated with the patients' available clinical chart data and follow-up. Between April 1995 and October 2004, 73 cases of CT-detected adrenal injuries were identified, including 48 men and 25 women, with an age range 6 to 90 years and a mean age of 42.7 years. Of the cases, 77% were right-sided, 15% were left-sided, and 8% were bilateral. The causes of injuries were motor vehicle collisions (75%), falls (14%), sports related (4%), and miscellaneous causes (7%). Associated trauma included injuries of the liver (43%), spleen (23%), lung (19%), and kidney (18%), as well as pneumothoraces/hemothoraces (22%). Skeletal injuries included fractures of the ribs, clavicles, and/or scapulae (39%), pelvis and hips (30%), and the spine (23%). Isolated adrenal trauma was seen in only 4% of the cases. The CT findings of adrenal trauma were focal hematoma (30%), indistinct (27%) or enlarged (18%) adrenal gland, gross (15%) or focal (7%) adrenal hemorrhage, and adrenal mass (11%). Associated CT findings

  16. CT Perfusion Dynamics of Intracranial Tuberculomas

    PubMed Central

    N., Jayakumar Peruvumba; Shivashankar, Ravishankar

    2015-01-01

    Aims To study perfusion characteristics of intracranial tuberculomas and analyze changes with anti tubercular treatment. Materials and Methods Nineteen patients of histologically proven intracranial tuberculomas were included in the study of which 9 were not on antitubercular treatment and ten were on antitubercular treatment (6 patients on treatment for less than 2 months and 4 were more than 6 months). All patients underwent CT perfusion (CTP) and CTP parameters like rCBV and rCBF were obtained from entire lesion, center and capsule of lesions and compared. Results CTP parameters like rCBF and rCBV were significantly low in all the three ROIs in the group not on treatment compared to that of on treatment ; rCBF and rCBV of entire lesion (p=0.018 and p=0.005 respectively), capsule (p=0.045 and p=0.010 respectively) and center of the lesion (p=0.020 and p=0.009) respectively). Tuberculomas on antitubercular treatment of more than six months showed reduced rCBF and rCBV in entire lesion (p=0.01 & p=0.01 respectively), capsule (p=0.04 & p=0.03 respectively) and center (p=0.08 & p=0.05 respectively) compared to those on treatment for less than two months. Similarly tuberculomas on treatment for six months did not show significant difference in rCBF and rCBV compared to tuberculomas who were not on treatment. Tuberculomas on treatment for less than two months showed statistically increased rCBF and rCBV in entire lesion (p=0.01 & p=0.04 respectively), capsule (p=0.03 & p=0.01 respectively) and center (p= 0.03 &=0.01) compared to those not on treatment. Conclusion Intracranial tuberculomas not on treatment and those on treatment for around six months show low perfusion and tuberculomas on treatment for less than two months show high perfusion. These findings suggest that serial perfusion profiles of tuberculomas on treatment could possibly be seen as surrogate markers of response to treatment. PMID:26155528

  17. Dosimetric feasibility of cone-beam CT-based treatment planning compared to CT-based treatment planning

    SciTech Connect

    Yoo, Sua . E-mail: sua.yoo@duke.edu; Yin, F.-F.

    2006-12-01

    Purpose: Cone-beam computed tomography (CBCT) images are currently used for positioning verification. However, it is yet unknown whether CBCT could be used in dose calculation for replanning in adaptive radiation therapy. This study investigates the dosimetric feasibility of CBCT-based treatment planning. Methods and Materials: Hounsfield unit (HU) values and profiles of Catphan, homogeneous/inhomogeneous phantoms, and various tissue regions of patients in CBCT images were compared to those in CT. The dosimetric consequence of the HU variation was investigated by comparing CBCT-based treatment plans to conventional CT-based plans for both phantoms and patients. Results: The maximum HU difference between CBCT and CT of Catphan was 34 HU in the Teflon. The differences in other materials were less than 10 HU. The profiles for the homogeneous phantoms in CBCT displayed reduced HU values up to 150 HU in the peripheral regions compared to those in CT. The scatter and artifacts in CBCT became severe surrounding inhomogeneous tissues with reduced HU values up to 200 HU. The MU/cGy differences were less than 1% for most phantom cases. The isodose distributions between CBCT-based and CT-based plans agreed very well. However, the discrepancy was larger when CBCT was scanned without a bowtie filter than with bowtie filter. Also, up to 3% dosimetric error was observed in the plans for the inhomogeneous phantom. In the patient studies, the discrepancies of isodose lines between CT-based and CBCT-based plans, both 3D and IMRT, were less than 2 mm. Again, larger discrepancy occurred for the lung cancer patients. Conclusion: This study demonstrated the feasibility of CBCT-based treatment planning. CBCT-based treatment plans were dosimetrically comparable to CT-based treatment plans. Dosimetric data in the inhomogeneous tissue regions should be carefully validated.

  18. Thin-Section CT Characteristics and Longitudinal CT Follow-up of Chemotherapy Induced Interstitial Pneumonitis: A Retrospective Cohort Study.

    PubMed

    Lee, Han Na; Kim, Mi Young; Koo, Hyun Jung; Kim, Sung-Soo; Yoon, Dok Hyun; Lee, Jae Cheol; Song, Jin Woo

    2016-01-01

    To describe the computed tomography (CT) features of chemotherapy-induced interstitial pneumonitis (CIIP) with longitudinal follow-up.The study was approved by the local ethics committee. One hundred consecutive patients with CIIP between May 2005 and March 2015 were retrospectively enrolled. The initial CT was reviewed by 2 independent chest radiologists and categorized into 1 of 4 CT patterns in accordance with the 2013 guidelines for idiopathic interstitial pneumonia: nonspecific interstitial pneumonia (NSIP), organizing pneumonia (OP), hypersensitivity pneumonitis (HP) mimicking desquamative interstitial pneumonitis, and diffuse alveolar damage (DAD). We assessed semiquantitative analysis on a 5% scale to assess the extent of parenchymal abnormalities (emphysema, reticulation, ground-glass opacity, consolidation, honeycombing cyst) and their distribution on initial (n = 100), subsequent (n = 87), and second follow-up CT (n = 48). Interval changes in extent on follow-up CT were compared using paired t test. The clinic-radiologic factors were compared between Group 1 (NSIP and OP patterns) and Group 2 (HP and DAD patterns) using χ and independent t tests.The most common pattern of CIIP on the initial CT was HP (51%), followed by NSIP (23%), OP (20%), and DAD (6%). Diffuse ground-glass opacity was the most common pulmonary abnormality. The predominant distribution was bilateral (99%) and symmetric (82%), with no craniocaudal (60%) or axial (79%) dominance. Subsequent and second follow-up CTs showed decreased extent of total pulmonary abnormalities (P < 0.001, respectively). In comparison with Group 1 CIIP, Group 2 CIIP was more likely to be caused by molecularly targeted drugs (P = 0.030), appeared earlier (P = 0.034), and underwent more complete resolution (P < 0.001). Use of a CT pattern-recognition approach to CIIP is appropriate and practical in interpreting radiological findings. PMID:26765442

  19. CT appearance of the normal appendix in adults.

    PubMed

    Tamburrini, Stefania; Brunetti, Arturo; Brown, Michèle; Sirlin, Claude B; Casola, Giovanna

    2005-10-01

    The aims of this study were to identify (1) the normal range of the appendix on computed tomography (CT), (2) the correlation of patient age and sex with the visibility and appearance of the appendix on CT, and (3) the normal variations in wall thickness, intraluminal content, and location of the appendix. Three hundred seventy-two outpatients underwent abdominopelvic CT. The scans were reviewed on the picture archiving and communication system and appendiceal outer-to-outer wall diameter, wall thickness, location, content and its correlation with appendix diameter were analyzed. The appendix was visualized in 305/372 patients. Its location relative to the cecum was highly variable. The diameter range was 3-10 mm; in 42% of cases the diameter was greater than 6 mm. When the intraluminal content (185/305) was visualized, the diameter was slightly superior to the mean (p=0.0156). In 329 CT scans in which oral contrast material was given, the appendix was filled by contrast material in 74/329 patients. The appendix wall thickness was measurable in 22/305 patients (average 0.15 cm). There is significant overlap between the normal and abnormal CT appearance of the appendix. Consequently the diagnosis of acute appendicitis should be based not only on the appearance of the appendix but also on the presence of secondary signs. PMID:15912331

  20. Metrology, applications and methods with high energy CT systems

    SciTech Connect

    Uhlmann, N.; Voland, V.; Salamon, M.; Hebele, S.; Boehnel, M.; Reims, N.; Schmitt, M.; Kasperl, S.

    2014-02-18

    The increase of Computed Tomography (CT) as an applicable metrology and Non Destructive Testing (NDT) method raises interest on developing the application fields to larger objects, which were rarely used in the past due to their requirements on the imaging system. Especially the classical X-ray generation techniques based on standard equipment restricted the applications of CT to typical material penetration lengths of only a few cm of steel. Even with accelerator technology that offers a suitable way to overcome these restrictions just the 2D radioscopy technique found a widespread application. Beside the production and detection of photons in the MeV range itself, the achievable image quality is limited using standard detectors due to the dominating absorption effect of Compton Scattering at high energies. Especially for CT reconstruction purposes these effects have to be considered on the development path from 2D to 3D imaging. Most High Energy CT applications are therefore based on line detectors shielding scattered radiation to a maximum with an increase in imaging quality but with time consuming large volume scan capabilities. In this contribution we present the High-Energy X-ray Imaging project at the Fraunhofer Development Centre for X-ray Technology with the characterization and the potential of the CT-system according to metrological and other application capabilities.