Science.gov

Sample records for enchanced ct scan

  1. 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 ...

  2. 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)

  3. CT scan

    MedlinePlus

    CAT scan; Computed axial tomography scan; Computed tomography scan ... Shaw AS, Prokop M. Computed tomography. In: Adam A, Dixon AK, Gillard JH, et al. eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging . 6th ...

  4. 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 ...

  5. 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

  6. 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- ...

  7. 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 ...

  8. 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- ...

  9. 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, ...

  10. 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- ...

  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. 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, ...

  13. 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 ...

  14. 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.

  15. 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 ...

  16. Knee CT scan

    MedlinePlus

    CAT scan - knee; Computed axial tomography scan - knee; Computed tomography scan - knee ... Saunders; 2015:chap 93. Shaw AS, Prokop M. Computed tomography. In: Adam A, Dixon AK, Gillard JH, Schaefer- ...

  17. 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 ...

  18. 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 ...

  19. 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 ...

  20. 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.

  1. 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

  2. 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

  3. 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 ...

  4. 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 ( ...

  5. 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 ...

  6. 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.

  7. 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

  8. Dynamic CT scanning of spinal column trauma

    SciTech Connect

    Brown, B.M.; Brant-Zawadzki, M.; Cann, C.E.

    1982-12-01

    Dynamic sequential computed tomographic scanning with automatic table incrementation uses low milliampere-second technique to eliminate tube cooling delays between scanning slices and, thus, markedly shortens examination times. A total of 25 patients with spinal column trauma involving 28 levels were studied with dynamic scans and retrospectively reviewed. Dynamic studies were considerably faster than conventional spine examinations and yielded reliable diagnosis. Bone disruption and subluxation was accurately evaluated, and the use of intrathecal metrizamide in low doses allowed direct visualization of spinal cord or radicular compromise. Multiplanar image reformation was aided by the dynamic incrementation technique, since motion between slices (and the resulting misregistration artifact on image reformation) was minimized. A phantom was devised to test spatial resolution of computed tomography for objects 1-3 mm in size and disclosed minimal differences for dynamic and conventional computed tomographic techniques in resolving medium-to-high-contrast objects.

  9. CT Scanning Imaging Method Based on a Spherical Trajectory.

    PubMed

    Chen, Ping; Han, Yan; Gui, Zhiguo

    2016-01-01

    In industrial computed tomography (CT), the mismatch between the X-ray energy and the effective thickness makes it difficult to ensure the integrity of projection data using the traditional scanning model, because of the limitations of the object's complex structure. So, we have developed a CT imaging method that is based on a spherical trajectory. Considering an unrestrained trajectory for iterative reconstruction, an iterative algorithm can be used to realise the CT reconstruction of a spherical trajectory for complete projection data only. Also, an inclined circle trajectory is used as an example of a spherical trajectory to illustrate the accuracy and feasibility of this new scanning method. The simulation results indicate that the new method produces superior results for a larger cone-beam angle, a limited angle and tabular objects compared with traditional circle trajectory scanning. PMID:26934744

  10. CT Scanning Imaging Method Based on a Spherical Trajectory

    PubMed Central

    2016-01-01

    In industrial computed tomography (CT), the mismatch between the X-ray energy and the effective thickness makes it difficult to ensure the integrity of projection data using the traditional scanning model, because of the limitations of the object’s complex structure. So, we have developed a CT imaging method that is based on a spherical trajectory. Considering an unrestrained trajectory for iterative reconstruction, an iterative algorithm can be used to realise the CT reconstruction of a spherical trajectory for complete projection data only. Also, an inclined circle trajectory is used as an example of a spherical trajectory to illustrate the accuracy and feasibility of this new scanning method. The simulation results indicate that the new method produces superior results for a larger cone-beam angle, a limited angle and tabular objects compared with traditional circle trajectory scanning. PMID:26934744

  11. [Usefulness of CT scan in the diagnosis of pulmonary aspergilloma].

    PubMed

    Gea, J; Arán, X; Sauleda, J; Broquetas, J M; Alegret, X; Bartrina, J

    1991-05-01

    Early diagnosis and precise anatomical localization of aspergillomas are essential for an effective treatment of their complications. We have evaluated the usefulness of thorax CT scan in the fulfillment of these objectives. Nine consecutive patients were studied with a presumable diagnosis of pulmonary aspergilloma. A thorax CT scan was performed in all patients (sections every 5 to 10 mm) in lying position and with lateral mobilizations. This technique allowed to rule out as fibrotic lesions some of the images previously attributed to mycetomas by conventional X-ray. On the other hand it helped to identify small size aspergillomas, to precise their localization and to demonstrate the possible communication between the main cavity and bronchial tree. In three patients who died in the period immediately following the study an excellent correlation between CT scan and underlying pathological lesions was observed. PMID:1891635

  12. Laser microbeam CT scanning of dosimetry gels

    NASA Astrophysics Data System (ADS)

    Maryanski, Marek J.; Ranade, Manisha K.

    2001-06-01

    A novel design of an optical tomographic scanner is described that can be used for 3D mapping of optical attenuation coefficient within translucent cylindrical objects with spatial resolution on the order of 100 microns. Our scanner design utilizes the cylindrical geometry of the imaged object to obtain the desired paths of the scanning light rays. A rotating mirror and a photodetector are placed at two opposite foci of the translucent cylinder that acts as a cylindrical lens. A He-Ne laser beam passes first through a focusing lens and then is reflected by the rotating mirror, so as to scan the interior of the cylinder with focused and parallel paraxial rays that are subsequently collected by the photodetector to produce the projection data, as the cylinder rotates in small angle increments between projections. Filtered backprojection is then used to reconstruct planar distributions of optical attenuation coefficient in the cylinder. Multiplanar scans are used to obtain a complete 3D tomographic reconstruction. Among other applications, the scanner can be used in radiation therapy dosimetry and quality assurance for mapping 3D radiation dose distributions in various types of tissue-equivalent gel phantoms that change their optical attenuation coefficients in proportion to the absorbed radiation dose.

  13. Digital radiographic localization for CT scanning of the larynx

    SciTech Connect

    Silverman, P.M.; Korobkin, M.; Rauch, R.F.

    1983-12-01

    Computed tomography (CT) of the larynx is the preferred method for staging laryngeal carcinoma and assessing the extent of injury from trauma. The standard method of examination consists of 5 mm contiguous scans throughout the larynx in quiet respiration. Scans are performed with the patient supine with the neck slightly extended allowing the long axis of the larynx to be perpendicular to the scanning plane. A complete examination requires scanning from the supraglottic region (level of hyoid bone) to the subglottic region (level of cricoid cartlage). In the authors' experience when this method is used, multiple scans are performed cephalad to the level of interest because no upper limit of the examination is established before transaxial scans are done. We have used the lateral digital radiograph of the neck to identify specific landmarks so that the upper and lower limets of the examination can be established before scanning.

  14. Treatment of Alzheimer Disease With CT Scans

    PubMed Central

    Moore, Eugene R.; Hosfeld, Victor D.; Nadolski, David L.

    2016-01-01

    Alzheimer disease (AD) primarily affects older adults. This neurodegenerative disorder is the most common cause of dementia and is a leading source of their morbidity and mortality. Patient care costs in the United States are about 200 billion dollars and will more than double by 2040. This case report describes the remarkable improvement in a patient with advanced AD in hospice who received 5 computed tomography scans of the brain, about 40 mGy each, over a period of 3 months. The mechanism appears to be radiation-induced upregulation of the patient’s adaptive protection systems against AD, which partially restored cognition, memory, speech, movement, and appetite. PMID:27103883

  15. 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.

  16. Harms of CT scanning prior to surgery for suspected appendicitis.

    PubMed

    Rogers, William; Hoffman, Jerome; Noori, Naudereh

    2015-02-01

    In this brief analysis we compare the risks and benefits of performing a CT scan to confirm appendicitis prior to surgery instead of operating based on the surgeon's clinical diagnosis. We conclude that the benefit of universal imaging is to avoid 12 unnecessary appendectomies but the cost of those 12 avoided surgeries is one cancer death due to the imaging. PMID:25429870

  17. Justification of CT scans using referral guidelines for imaging.

    PubMed

    Stanescu, G; Rosca-Fartat, G; Stanescu, D

    2015-07-01

    This study analyses the efficiency of the justification of individual computed tomography (CT) procedures using the good practice guide. The conformity of the CT scans with guide's recommendations was retrospectively analysed in a paediatric emergency hospital in Romania. The involved patient doses were estimated. The results show that around one-third of the examinations were not prescribed in conformity with the guide's recommendations, but these results are affected by unclear guide provisions, discussed here. The implications of the provisions of the revised International Atomic Energy Agency's Basic Safety Standards and of the Council Directive 2013/59/EURATOM were analysed. The education and training courses for medical doctors disseminating the provisions of the good practice guide should be considered as the main support for the justification of the CT scans at the individual level. PMID:25805882

  18. An automatic approach for 3D registration of CT scans

    NASA Astrophysics Data System (ADS)

    Hu, Yang; Saber, Eli; Dianat, Sohail; Vantaram, Sreenath Rao; Abhyankar, Vishwas

    2012-03-01

    CT (Computed tomography) is a widely employed imaging modality in the medical field. Normally, a volume of CT scans is prescribed by a doctor when a specific region of the body (typically neck to groin) is suspected of being abnormal. The doctors are required to make professional diagnoses based upon the obtained datasets. In this paper, we propose an automatic registration algorithm that helps healthcare personnel to automatically align corresponding scans from 'Study' to 'Atlas'. The proposed algorithm is capable of aligning both 'Atlas' and 'Study' into the same resolution through 3D interpolation. After retrieving the scanned slice volume in the 'Study' and the corresponding volume in the original 'Atlas' dataset, a 3D cross correlation method is used to identify and register various body parts.

  19. Interactive annotation of textures in thoracic CT scans

    NASA Astrophysics Data System (ADS)

    Kockelkorn, Thessa T. J. P.; de Jong, Pim A.; Gietema, Hester A.; Grutters, Jan C.; Prokop, Mathias; van Ginneken, Bram

    2010-03-01

    This study describes a system for interactive annotation of thoracic CT scans. Lung volumes in these scans are segmented and subdivided into roughly spherical volumes of interest (VOIs) with homogeneous texture using a clustering procedure. For each 3D VOI, 72 features are calculated. The observer inspects the scan to determine which textures are present and annotates, with mouse clicks, several VOIs of each texture. Based on these annotations, a k-nearest-neighbor classifier is trained, which classifies all remaining VOIs in the scan. The algorithm then presents a slice with suggested annotations to the user, in which the user can correct mistakes. The classifier is retrained, taking into account these new annotations, and the user is presented another slice for correction. This process continues until at least 50% of all lung voxels in the scan have been classified. The remaining VOIs are classified automatically. In this way, the entire lung volume is annotated. The system has been applied to scans of patients with usual and non-specific interstitial pneumonia. The results of interactive annotation are compared to a setup in which the user annotates all predefined VOIs manually. The interactive system is 3.7 times as fast as complete manual annotation of VOIs and differences between the methods are similar to interobserver variability. This is a first step towards precise volumetric quantitation of texture patterns in thoracic CT in clinical research and in clinical practice.

  20. Semi-automatic classification of textures in thoracic CT scans

    NASA Astrophysics Data System (ADS)

    Kockelkorn, Thessa T. J. P.; de Jong, Pim A.; Schaefer-Prokop, Cornelia M.; Wittenberg, Rianne; Tiehuis, Audrey M.; Gietema, Hester A.; Grutters, Jan C.; Viergever, Max A.; van Ginneken, Bram

    2016-08-01

    The textural patterns in the lung parenchyma, as visible on computed tomography (CT) scans, are essential to make a correct diagnosis in interstitial lung disease. We developed one automatic and two interactive protocols for classification of normal and seven types of abnormal lung textures. Lungs were segmented and subdivided into volumes of interest (VOIs) with homogeneous texture using a clustering approach. In the automatic protocol, VOIs were classified automatically by an extra-trees classifier that was trained using annotations of VOIs from other CT scans. In the interactive protocols, an observer iteratively trained an extra-trees classifier to distinguish the different textures, by correcting mistakes the classifier makes in a slice-by-slice manner. The difference between the two interactive methods was whether or not training data from previously annotated scans was used in classification of the first slice. The protocols were compared in terms of the percentages of VOIs that observers needed to relabel. Validation experiments were carried out using software that simulated observer behavior. In the automatic classification protocol, observers needed to relabel on average 58% of the VOIs. During interactive annotation without the use of previous training data, the average percentage of relabeled VOIs decreased from 64% for the first slice to 13% for the second half of the scan. Overall, 21% of the VOIs were relabeled. When previous training data was available, the average overall percentage of VOIs requiring relabeling was 20%, decreasing from 56% in the first slice to 13% in the second half of the scan.

  1. Double-low protocol for hepatic dynamic CT scan

    PubMed Central

    Zhang, Xiuli; Li, Shaodong; Liu, Wenlou; Huang, Ning; Li, Jingjing; Cheng, Li; Xu, Kai

    2016-01-01

    Abstract The radiation-induced carcinogenesis from computed tomography (CT) and iodine contrast agent induced nephropathy has attracted international attention. The reduction of the radiation dose and iodine intake in CT scan is always a direction for researchers to strive. The purpose of this study was to evaluate the feasibility of a “double-low” (i.e., low tube voltage and low-dose iodine contrast agent) scanning protocol for dynamic hepatic CT with the adaptive statistical iterative reconstruction (ASIR) in patients with a body mass index (BMI) of 18.5 to 27.9 kg/m2. A total of 128 consecutive patients with a BMI between 18.5 and 27.9 kg/m2 were randomly assigned into 3 groups according to tube voltage, iodine contrast agent, and reconstruction algorithms. Group A (the “double-low” protocol): 100 kVp tube voltage with 40% ASIR, iodixanol at 270 mg I/mL, group B: 120 kVp tube voltage with filtered back projection (FBP), iodixanol at 270 mg I/ mL, and group C: 120 kVp tube voltage with FBP, ioversol at 350 mg I/ mL. The volume CT dose index (CTDIvol) and effective dose (ED) in group A were lower than those in group B and C (all P < 0.01). The iodine intake in group A was decreased by approximately 26.5% than group C, whereas no statistical difference was observed between group A and B (P > 0.05). There was no significant difference of the CT values between group A and C (P > 0.05), which both showed higher CT values than that in group B (P < 0.001). However, no statistic difference was observed in the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and image-quality scores among the 3 groups (all P > 0.05). Near-perfect consistency of the evaluation for group A, B, and C (Kenall's W = 0.921, 0.874, and 0.949, respectively) was obtained by the 4 readers with respect to the overall image quality. These results suggested that the “double-low” protocol with ASIR algorithm for multi-phase hepatic CT scan

  2. Variation of quantitative emphysema measurements from CT scans

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

    Emphysema is a lung disease characterized by destruction of the alveolar air sacs and is associated with long-term respiratory dysfunction. CT scans allow for imaging of the anatomical basis of emphysema, and several measures have been introduced for the quantification of the extent of disease. In this paper we compare these measures for repeatability over time. The measures of interest in this study are emphysema index, mean lung density, histogram percentile, and the fractal dimension. To allow for direct comparisons, the measures were normalized to a 0-100 scale. These measures have been computed for a set of 2,027 scan pairs in which the mean interval between scans was 1.15 years (σ: 93 days). These independent pairs were considered with respect to three different scanning conditions (a) 223 pairs where both were scanned with a 5 mm slice thickness protocol, (b) 695 with the first scanned with the 5 mm protocol and the second with a 1.25 mm protocol, and (c) 1109 pairs scanned both times using a 1.25 mm protocol. We found that average normalized emphysema index and histogram percentiles scores increased by 5.9 and 11 points respectively, while the fractal dimension showed stability with a mean difference of 1.2. We also found, a 7 point bias introduced for emphysema index under condition (b), and that the fractal dimension measure is least affected by scanner parameter changes.

  3. Radiation dose reduction in pediatric abdominal CT scanning

    SciTech Connect

    Kamel, I.R.

    1993-01-01

    A clinical trial was designed to test whether a significantly lower radiation dose technique could be used for pediatric abdominal CT scanning without loss of diagnostic image quality. The study included pediatric patients referred to radiology from the Children's Hospital and clinics at The University of Michigan. Seventy-eight cases were included in the study, 36 cases in the experimental group and 42 in the control group. Patient characteristics in both groups were comparable in every respect except for the technical factors used to expose the pelvis. Patients in the experimental group were scanned with a technique using 80 mAs while those in the control group were scanned with the conventional technique of 240 mAs. Therefore, the radiation dose to the pelvis was three times higher in the control group than in the experimental group. Scans were evaluated by two experienced pediatric radiologists who assessed anatomical details, image resolution and the degree of confidence in reaching a diagnosis. The low-mAs technique did not result in reduction of diagnostic image quality or the confidence in reaching a diagnosis. In conclusion, the radiation dose resulting from pediatric CT of the pelvis may be reduced by a factor of three with equivalent medical benefit.

  4. 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.

  5. Quantitative analysis of CT scans of ceramic candle filters

    SciTech Connect

    Ferer, M.V.; Smith, D.H.

    1996-12-31

    Candle filters are being developed to remove coal ash and other fine particles (<15{mu}m) from hot (ca. 1000 K) gas streams. In the present work, a color scanner was used to digitize hard-copy CT X-ray images of cylindrical SiC filters, and linear regressions converted the scanned (color) data to a filter density for each pixel. These data, with the aid of the density of SiC, gave a filter porosity for each pixel. Radial averages, density-density correlation functions, and other statistical analyses were performed on the density data. The CT images also detected the presence and depth of cracks that developed during usage of the filters. The quantitative data promise to be a very useful addition to the color images.

  6. Semi-automatic classification of textures in thoracic CT scans.

    PubMed

    Kockelkorn, Thessa T J P; de Jong, Pim A; Schaefer-Prokop, Cornelia M; Wittenberg, Rianne; Tiehuis, Audrey M; Gietema, Hester A; Grutters, Jan C; Viergever, Max A; van Ginneken, Bram

    2016-08-21

    The textural patterns in the lung parenchyma, as visible on computed tomography (CT) scans, are essential to make a correct diagnosis in interstitial lung disease. We developed one automatic and two interactive protocols for classification of normal and seven types of abnormal lung textures. Lungs were segmented and subdivided into volumes of interest (VOIs) with homogeneous texture using a clustering approach. In the automatic protocol, VOIs were classified automatically by an extra-trees classifier that was trained using annotations of VOIs from other CT scans. In the interactive protocols, an observer iteratively trained an extra-trees classifier to distinguish the different textures, by correcting mistakes the classifier makes in a slice-by-slice manner. The difference between the two interactive methods was whether or not training data from previously annotated scans was used in classification of the first slice. The protocols were compared in terms of the percentages of VOIs that observers needed to relabel. Validation experiments were carried out using software that simulated observer behavior. In the automatic classification protocol, observers needed to relabel on average 58% of the VOIs. During interactive annotation without the use of previous training data, the average percentage of relabeled VOIs decreased from 64% for the first slice to 13% for the second half of the scan. Overall, 21% of the VOIs were relabeled. When previous training data was available, the average overall percentage of VOIs requiring relabeling was 20%, decreasing from 56% in the first slice to 13% in the second half of the scan. PMID:27436568

  7. Automated segmentation of mesothelioma volume on CT scan

    NASA Astrophysics Data System (ADS)

    Zhao, Binsheng; Schwartz, Lawrence; Flores, Raja; Liu, Fan; Kijewski, Peter; Krug, Lee; Rusch, Valerie

    2005-04-01

    In mesothelioma, response is usually assessed by computed tomography (CT). In current clinical practice the Response Evaluation Criteria in Solid Tumors (RECIST) or WHO, i.e., the uni-dimensional or the bi-dimensional measurements, is applied to the assessment of therapy response. However, the shape of the mesothelioma volume is very irregular and its longest dimension is almost never in the axial plane. Furthermore, the sections and the sites where radiologists measure the tumor are rather subjective, resulting in poor reproducibility of tumor size measurements. We are developing an objective three-dimensional (3D) computer algorithm to automatically identify and quantify tumor volumes that are associated with malignant pleural mesothelioma to assess therapy response. The algorithm first extracts the lung pleural surface from the volumetric CT images by interpolating the chest ribs over a number of adjacent slices and then forming a volume that includes the thorax. This volume allows a separation of mesothelioma from the chest wall. Subsequently, the structures inside the extracted pleural lung surface, including the mediastinal area, lung parenchyma, and pleural mesothelioma, can be identified using a multiple thresholding technique and morphological operations. Preliminary results have shown the potential of utilizing this algorithm to automatically detect and quantify tumor volumes on CT scans and thus to assess therapy response for malignant pleural mesothelioma.

  8. 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).

  9. Multi-detector row CT scanning in Paleoanthropology at various tube current settings and scanning mode.

    PubMed

    Badawi-Fayad, J; Yazbeck, C; Balzeau, A; Nguyen, T H; Istoc, A; Grimaud-Hervé, D; Cabanis, E- A

    2005-12-01

    The purpose of this study was to determine the optimal tube current setting and scanning mode for hominid fossil skull scanning, using multi-detector row computed tomography (CT). Four fossil skulls (La Ferrassie 1, Abri Pataud 1, CroMagnon 2 and Cro-Magnon 3) were examined by using the CT scanner LightSpeed 16 (General Electric Medical Systems) with varying dose per section (160, 250, and 300 mAs) and scanning mode (helical and conventional). Image quality of two-dimensional (2D) multiplanar reconstructions, three-dimensional (3D) reconstructions and native images was assessed by four reviewers using a four-point grading scale. An ANOVA (analysis of variance) model was used to compare the mean score for each sequence and the overall mean score according to the levels of the scanning parameters. Compared with helical CT (mean score=12.03), the conventional technique showed sustained poor image quality (mean score=4.17). With the helical mode, we observed a better image quality at 300 mAs than at 160 in the 3D sequences (P=0.03). Whereas in native images, a reduction in the effective tube current induced no degradation in image quality (P=0.05). Our study suggests a standardized protocol for fossil scanning with a 16 x 0.625 detector configuration, a 10 mm beam collimation, a 0.562:1 acquisition mode, a 0.625/0.4 mm slice thickness/reconstruction interval, a pitch of 5.62, 120 kV and 300 mAs especially when a 3D study is required. PMID:16211320

  10. CT Scans of Soil Specimen Processed in Space

    NASA Technical Reports Server (NTRS)

    1998-01-01

    CT scans of the spcimens on STS-79 reveal internal cone-shaped features and radial patterns not seen in specimens processed on the ground. The lighter areas are the densest in these images. CT scans produced richly detailed images allowing scientists to build 3D models of the interior of the specimens that can be compared with microscopic examination of thin slices. This view is made from a series of horizontal slices. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: Los Alamos National Laboratory and the University of Colorado at Boulder.

  11. CT Scans of Soil Specimen Processed in Space

    NASA Technical Reports Server (NTRS)

    1998-01-01

    CT scans of the spcimens on STS-79 reveal internal cone-shaped features and radial patterns not seen in specimens processed on the ground. The lighter areas are the densest in these images. CT scans produced richly detailed images allowing scientists to build 3D models of the interior of the specimens that can be compared with microscopic examination of thin slices. These views depict vertical slices from side to middle of a flight specimen. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: Los Alamos National Laboratory and the University of Colorado at Boulder.

  12. CT Scans of Soil Specimen Processed in Space

    NASA Technical Reports Server (NTRS)

    1998-01-01

    CT scans of the specimens on STS-79 reveal internal cone-shaped features and radial patterns not seen in specimens processed on the ground. The lighter areas are the densest in these images. CT scans produced richly detailed images allowing scientists to build 3D models of the interior of the specimens that can be compared with microscopic examination of thin slices. This view is made from three orthogonal slices. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: Los Alamos National Laboratory and the University of Colorado at Boulder).

  13. CT Scans of Soil Specimen Processed in Space

    NASA Technical Reports Server (NTRS)

    1998-01-01

    CT scans of the spcimens on STS-79 reveal internal cone-shaped features and radial patterns not seen in specimens processed on the ground. The lighter areas are the densest in these images. CT scans produced richly detailed images allowing scientists to build 3D models of the interior of the specimens that can be compared with microscopic examination of thin slices. This view depict horizontal slices from top to bottom of a flight specimen. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: Los Alamos National Laboratory and the University of Colorado at Boulder.

  14. Lipiodol enhanced CT scanning of malignant hepatic tumors.

    PubMed

    Eurvilaichit, C

    2000-04-01

    From August 1984 to March 1991, 41 patients with malignant liver tumors, 30 males and 11 females, aged 30-75 years were treated at Ramathibodi Hospital with injection of mitomycin-C lipiodol emulsion into the tumor via the feeding artery followed by embolization of the feeding artery with gelfoam particles. The patients comprised 30 cases of hepatocellular carcinoma, 4 cases of cholangiocarcinoma and 7 cases of metastatic tumors of which one was from CA stomach, three were from CA breast, and three from CA colon. The vascularity of the tumor was assessed in angiogram obtained prior to treatment and retention pattern of lipiodol in the tumor was evaluated in lipiodol-enhanced CT scan images taken 2-4 weeks following therapy. The results showed that lipiodol CT scan images exhibited four patterns of lipiodol retention in the tumor appearing as opacity as follows (1) homogenous (2) heterogeneous (3) ring-like and (4) none. Lipiodol retention pattern appeared to be somewhat related to vascularity of the tumor. Most of the hypervascular tumors such as hepatocellular carcinoma had homogeneous lipiodol accumulation pattern if the tumor size was less than 5 cm. Metastatic tumors and cholangiocarcinoma showed heterogeneous or ring-like pattern of lipiodol accumulation because they were relatively hypovascular. Hypervascular hepatocellular carcinoma may exhibit heterogeneous or ring-like pattern if they are larger than 5 cms, and have multiple feeding arteries, necrosis or AV shunting. Hepatocellular carcinoma with AV shunting may not show any lipiodol accumulation at all. PMID:10808700

  15. 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

  16. To Scan or not to Scan: Consideration of Medical Benefit in the Justification of CT Scanning.

    PubMed

    McCollough, Cynthia H

    2016-03-01

    While there are ongoing debates with regard to the level of risk, if any, associated with medical imaging, the benefits from medical imaging exams are well documented. This forum article looks at outcome-based medical studies and guidance from expert panels in an effort to bring the benefits of medical imaging, specifically CT imaging, into focus. The position is taken that imaging, medical, and safety communities must not continue to discuss small hypothetical risks from ionizing radiation without emphasizing the large well-documented benefits from medical imaging exams that use ionizing radiation. PMID:26808885

  17. Orthogonal-rotating tetrahedral scanning for cone-beam CT

    NASA Astrophysics Data System (ADS)

    Ye, Ivan B.; Wang, Ge

    2012-10-01

    In this article, a cone-beam CT scanning mode is designed assuming four x-ray sources and a spherical sample. The x-ray sources are mounted at the vertices of a regular tetrahedron. On the circumsphere of the tetrahedron, four detection panels are mounted opposite to each vertex. To avoid x-ray interference, the largest half angle of each x-ray cone beam is 27°22', while the radius of the largest ball fully covered by all the cone beams is 0.460, when the radius of the circumsphere is 1. Several scanning schemes are proposed which consist of two rotations about orthogonal axes, such that each quarter turn provides sufficient data for theoretically exact and stable reconstruction. This design can be used in biomedical or industrial settings, such as when a sequence of reconstructions of an object is desired. Similar scanning schemes based on other regular or irregular polyhedra and various rotation speeds are also discussed.

  18. Effect of spineboard and headblocks on the image quality of head CT scans.

    PubMed

    Hemmes, Baukje; Jeukens, Cécile R L P N; Al-Haidari, Aliaa; Hofman, Paul A M; Vd Linden, Ed S; Brink, Peter R G; Poeze, Martijn

    2016-06-01

    Trauma patients at risk for, or suspected of, spinal injury are frequently transported to hospital using full spinal immobilisation. At the emergency department, immobilisation is often maintained until radiological work-up is completed. In this study, we examined how these devices for spinal stabilization influence visual image quality. Image quality was judged for both patient CT scans and phantom CT scans. CT scans of 217 patients were assessed retrospectively by two radiologists for visual scoring of image quality, scoring both quantity and impact of artifacts caused by the immobilization devices. For the phantom CT scans, eight set-ups were made, using a vacuum mattress without headblocks and a rigid and a soft-layered spineboard without headblocks, with standard soft-foam headblocks, or with new design headblocks. Overall, artifacts were found in 67 % of CT scans of patients on immobilization devices, which hampered diagnosis in 10 % of the cases. In the phantom CT scans, artifacts were present in all set-ups with one or more devices present and were seen in 20 % of all scan slices. The presence of headblocks resulted in more artifacts in both the patient CT scans and the phantom CT scans. Considerable effort should therefore be made to adjust the design of the immobilization devices and to remove the headblocks before CT scans are made. PMID:27091739

  19. Exploring miniature insect brains using micro-CT scanning techniques.

    PubMed

    Smith, Dylan B; Bernhardt, Galina; Raine, Nigel E; Abel, Richard L; Sykes, Dan; Ahmed, Farah; Pedroso, Inti; Gill, Richard J

    2016-01-01

    The capacity to explore soft tissue structures in detail is important in understanding animal physiology and how this determines features such as movement, behaviour and the impact of trauma on regular function. Here we use advances in micro-computed tomography (micro-CT) technology to explore the brain of an important insect pollinator and model organism, the bumblebee (Bombus terrestris). Here we present a method for accurate imaging and exploration of insect brains that keeps brain tissue free from trauma and in its natural stereo-geometry, and showcase our 3D reconstructions and analyses of 19 individual brains at high resolution. Development of this protocol allows relatively rapid and cost effective brain reconstructions, making it an accessible methodology to the wider scientific community. The protocol describes the necessary steps for sample preparation, tissue staining, micro-CT scanning and 3D reconstruction, followed by a method for image analysis using the freeware SPIERS. These image analysis methods describe how to virtually extract key composite structures from the insect brain, and we demonstrate the application and precision of this method by calculating structural volumes and investigating the allometric relationships between bumblebee brain structures. PMID:26908205

  20. Exploring miniature insect brains using micro-CT scanning techniques

    PubMed Central

    Smith, Dylan B.; Bernhardt, Galina; Raine, Nigel E.; Abel, Richard L.; Sykes, Dan; Ahmed, Farah; Pedroso, Inti; Gill, Richard J.

    2016-01-01

    The capacity to explore soft tissue structures in detail is important in understanding animal physiology and how this determines features such as movement, behaviour and the impact of trauma on regular function. Here we use advances in micro-computed tomography (micro-CT) technology to explore the brain of an important insect pollinator and model organism, the bumblebee (Bombus terrestris). Here we present a method for accurate imaging and exploration of insect brains that keeps brain tissue free from trauma and in its natural stereo-geometry, and showcase our 3D reconstructions and analyses of 19 individual brains at high resolution. Development of this protocol allows relatively rapid and cost effective brain reconstructions, making it an accessible methodology to the wider scientific community. The protocol describes the necessary steps for sample preparation, tissue staining, micro-CT scanning and 3D reconstruction, followed by a method for image analysis using the freeware SPIERS. These image analysis methods describe how to virtually extract key composite structures from the insect brain, and we demonstrate the application and precision of this method by calculating structural volumes and investigating the allometric relationships between bumblebee brain structures. PMID:26908205

  1. 3D dosimetry by optical-CT scanning

    PubMed Central

    Oldham, Mark

    2007-01-01

    The need for an accurate, practical, low-cost 3D dosimetry system is becoming ever more critical as modern dose delivery techniques increase in complexity and sophistication. A recent report from the Radiological Physics Center (RPC) (1), revealed that 38% of institutions failed the head-and-neck IMRT phantom credentialing test at the first attempt. This was despite generous passing criteria (within 7% dose-difference or 4mm distance-to-agreement) evaluated at a half-dozen points and a single axial plane. The question that arises from this disturbing finding is – what percentage of institutions would have failed if a comprehensive 3D measurement had been feasible, rather than measurements restricted to the central film-plane and TLD points? This question can only be adequately answered by a comprehensive 3D-dosimetry system, which presents a compelling argument for its development as a clinically viable low cost dosimetry solution. Optical-CT dosimetry is perhaps the closest system to providing such a comprehensive solution. In this article, we review the origins and recent developments of optical-CT dosimetry systems. The principle focus is on first generation systems known to have highest accuracy but longer scan times. PMID:17460781

  2. Union of Scaphoid Waist Fractures Assessed by CT Scan

    PubMed Central

    Clementson, Martin; Jørgsholm, Peter; Besjakov, Jack; Björkman, Anders; Thomsen, Niels

    2015-01-01

    Background Union of a scaphoid fracture is difficult to assess on a standard series of radiographs. An unnecessary and prolonged immobilization is inconvenient and may impair functional outcome. Although operative treatment permits early mobilization, its influence on time to union is still uncertain. Purpose To assess union of scaphoid waist fractures based on computed tomography (CT) scan at 6 weeks, and to compare time to union between conservative treatment and arthroscopically assisted screw fixation. Patients and methods CT scan in the longitudinal axis of the scaphoid was used to provide fracture characteristics, and to assess bone union at 6 weeks in 65 consecutive patients with scaphoid waist fractures. In a randomized subgroup from this cohort with nondisplaced fractures, we compared time to union between conservative treatment (n = 23) and arthroscopically assisted screw fixation (n = 15). Results Overall, at 6 weeks we found a 90% union rate for non- or minimally displaced fracture treated conservatively, and 82% for those who underwent surgery. In the randomized subgroup of nondisplaced fractures, no significant difference in time to union was demonstrated between those treated conservatively and those who underwent surgery. The conservatively treated fractures from this subgroup with prolonged time to union (10 to 14 weeks) were comminuted, demonstrating a radial cortical or corticospongious fragment. Conclusion The majority of non- or minimally displaced scaphoid waist fractures are sufficiently treated with 6 weeks in a cast. Screw fixation does not reduce time to fracture union compared with conservative treatment. Level of Evidence level II, Therapeutic study PMID:25709879

  3. Slowing the increase in the population dose resulting from CT scans.

    PubMed

    Brenner, D J

    2010-12-01

    The annual number of CT scans in the U.S. is now over 70 million. The concern is that organ doses from CT are typically far larger than those from conventional X-ray examinations, and there is epidemiological evidence of a small but significant increased cancer risk at typical CT doses. Because CT is a superb diagnostic tool and because individual CT risks are small, when a CT scan is clinically indicated, the CT benefit/risk balance is by far in the patient's favor. Nevertheless, CT should operate under the ALARA (As Low As Reasonably Achievable) principle, and opportunities exist to reduce the significant population dose associated with CT without compromising patient care. The first opportunity is to reduce the dose per scan, and improved technology has much potential here. The second opportunity is selective replacement of CT with other modalities, such as for many head and spinal examinations (with MRI), and for diagnosing appendicitis (selective use of ultrasound + CT). Finally, a fraction of CT scans could be avoided entirely, as indicated by CT decision rules: Clinical decision rules for CT use represent a powerful approach for slowing down the increase in CT use, because they have the potential to overcome some of the major factors that result in some CT scans being undertaken when they are potentially not clinically helpful. In the U.S. and potentially elsewhere, legislative approaches are a possible option, to improve quality control and reduce clinically unneeded CT use, and it is also possible that upcoming changes in heath care economics will tend to slow the increase in such CT use. PMID:20731591

  4. Childhood CT scans linked to leukemia and brain cancer later in life

    Cancer.gov

    Children and young adults scanned multiple times by computed tomography (CT), a commonly used diagnostic tool, have a small increased risk of leukemia and brain tumors in the decade following their first scan.

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

    PubMed Central

    2005-01-01

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

  6. Thoracic CT scanning for mediastinal Hodgkin's disease: results and therapeutic implications

    SciTech Connect

    Rostock, R.A.; Siegelman, S.S.; Lenhard, R.E.; Wharam, M.D.; Order, S.E.

    1983-10-01

    Thoracic CT scans were performed on 42 newly diagnosed patients with Hodgkin's disease. Five of 10 patients with negative chest X ray (CXR) had abnormal thoracic CT scans. Among the remaining 32 patients with mediastinal Hodgkin's disease (MHD) on CXR, pericardial (Ep) and chest wall invasion (Ec) were the two most common sites of involvement which were detectable by CT scan alone. Ep and Ec accounted for 16 of 19 of the changes in treatment portal or philosophy based on CT scan findings. Because of the high risk of cardiac or pulmonary radiation toxicity in Ep or Ec, radiation treatment alone may be inadequate. Treatment of mediastinal Hodgkin's disease is reviewed here. The use of CT scans for identification of Ep, Ec, and other abnormalities will allow for more precise treatment, further define the use of conventional radiotherapy, combined modality therapy or whole lung irradiation, and allow more accurate analysis of treatment results.

  7. Knowledge Representation Of CT Scans Of The Head

    NASA Astrophysics Data System (ADS)

    Ackerman, Laurens V.; Burke, M. W.; Rada, Roy

    1984-06-01

    We have been investigating diagnostic knowledge models which assist in the automatic classification of medical images by combining information extracted from each image with knowledge specific to that class of images. In a more general sense we are trying to integrate verbal and pictorial descriptions of disease via representations of knowledge, study automatic hypothesis generation as related to clinical medicine, evolve new mathematical image measures while integrating them into the total diagnostic process, and investigate ways to augment the knowledge of the physician. Specifically, we have constructed an artificial intelligence knowledge model using the technique of a production system blending pictorial and verbal knowledge about the respective CT scan and patient history. It is an attempt to tie together different sources of knowledge representation, picture feature extraction and hypothesis generation. Our knowledge reasoning and representation system (KRRS) works with data at the conscious reasoning level of the practicing physician while at the visual perceptional level we are building another production system, the picture parameter extractor (PPE). This paper describes KRRS and its relationship to PPE.

  8. Osmotic blood-brain barrier modification: clinical documentation by enhanced CT scanning and/or radionuclide brain scanning

    SciTech Connect

    Neuwelt, E.A.; Specht, H.D.; Howieson, J.; Haines, J.E.; Bennett, M.J.; Hill, S.A.; Frenkel, E.P.

    1983-10-01

    Results of initial clinical trials of brain tumor chemotherapy after osmotic blood-brain barrier disruption are promising. In general, the procedure is well tolerated. The major complication has been seizures. In this report, data are presented which indicate that the etiology of these seizures is related to the use of contrast agent (meglumine iothalamate) to monitor barrier modification. A series of 19 patients underwent a total of 85 barrier modification procedures. Documentation of barrier disruption was monitored by contrast-enhanced computed tomographic (CT) scanning, radionuclide brain scanning, or a combination of both techniques. In 56 procedures (19 patients) monitored by enhanced CT, seizures occurred a total of 10 times in eight patients. Twenty-three barrier modification procedures (in nine of these 19 patients) documented by nuclear brain scans alone, however, resulted in only one focal motor seizure in each of two patients. In eight of the 19 patients who had seizures after barrier disruption and enhanced CT scan, four subsequently had repeat procedures monitored by radionuclide scan alone. In only one of these patients was further seizure activity noted; a single focal motor seizure was observed. Clearly, the radionuclide brain scan does not have the sensitivity and spatial resolution of enhanced CT, but at present it appears safer to monitor barrier modification by this method and to follow tumor growth between barrier modifications by enhanced CT. Four illustrative cases showing methods, problems, and promising results are presented.

  9. Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

    SciTech Connect

    Alva-Sánchez, Héctor

    2014-11-07

    In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

  10. Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

    NASA Astrophysics Data System (ADS)

    Alva-Sánchez, Héctor; Reynoso-Mejía, Alberto; Casares-Cruz, Katiuzka; Taboada-Barajas, Jesús

    2014-11-01

    In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

  11. Physical evaluation of CT scan methods for radiation therapy planning: comparison of fast, slow and gating scan using the 256-detector row CT scanner

    NASA Astrophysics Data System (ADS)

    Mori, Shinichiro; Kanematsu, Nobuyuki; Mizuno, Hideyuki; Sunaoka, Masayoshi; Endo, Masahiro

    2006-02-01

    Although slow-rotation CT scanning (slow-scan CT: SSCT) has been used for radiation therapy planning, based on the rationale that the average duration of the human respiratory cycle is 4 s, a number of physical and quantitative questions require answering before it can be adopted for clinical use. This study was performed to evaluate SSCT physically in comparison with other scan methods, including respiratory-gated CT (RGCT), and to develop procedures to improve treatment accuracy. Evaluation items were geometrical accuracy, volume accuracy, water equivalent length and dose distribution using the 256-detector row CT with three scan methods. Fast-scan CT (FSCT) was defined as obtaining all respiratory phases in cine scan mode at 1.0 s per rotation. FSCT-ave was the averaged FSCT images in all respiratory phases, obtained by reconstructing short time intervals. SSCT has been defined as scanning with slow gantry rotation to capture the whole respiratory cycle in one rotation. RGCT was scanned at the most stable point in the respiratory cycle, which provides the same image as that by FSCT at the most stable point. Results showed that all evaluation items were dependent on motion characteristics. The findings of this study indicate that 3D planning based solely on SSCT under free breathing may result in underdosing of the target volume and increase toxicity to surrounding normal tissues. Of the three methods, RGCT showed the best ability to significantly increase the accuracy of dose distribution, and provided more information to minimize the margins. FSCT-ave is a satisfactory radiotherapy planning alternative if RGCT is not available.

  12. 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 ...

  13. Few CT Scan Abnormalities Found Even in Neurologically Impaired Learning Disabled Children.

    ERIC Educational Resources Information Center

    Denckla, Martha Bridge; And Others

    1985-01-01

    Most of 32 learning disabled children (seven to 14 years old) with neurological lateralization characteristics marked by right and left hemispheres had a normal CT (computerized tomography) scan. (CL)

  14. Concepts and Analyses in the CT Scanning of Root Systems and Leaf Canopies: A Timely Summary

    PubMed Central

    Lafond, Jonathan A.; Han, Liwen; Dutilleul, Pierre

    2015-01-01

    Non-medical applications of computed tomography (CT) scanning have flourished in recent years, including in Plant Science. This Perspective article on CT scanning of root systems and leaf canopies is intended to be of interest to three categories of readers: those who have not yet tried plant CT scanning, and should find inspiration for new research objectives; readers who are on the learning curve with applications—here is helpful advice for them; and researchers with greater experience—the field is evolving quickly and it is easy to miss aspects. Our conclusion is that CT scanning of roots and canopies is highly demanding in terms of technology, multidisciplinarity and big-data analysis, to name a few areas of expertise, but eventually, the reward for researchers is directly proportional! PMID:26734022

  15. Concepts and Analyses in the CT Scanning of Root Systems and Leaf Canopies: A Timely Summary.

    PubMed

    Lafond, Jonathan A; Han, Liwen; Dutilleul, Pierre

    2015-01-01

    Non-medical applications of computed tomography (CT) scanning have flourished in recent years, including in Plant Science. This Perspective article on CT scanning of root systems and leaf canopies is intended to be of interest to three categories of readers: those who have not yet tried plant CT scanning, and should find inspiration for new research objectives; readers who are on the learning curve with applications-here is helpful advice for them; and researchers with greater experience-the field is evolving quickly and it is easy to miss aspects. Our conclusion is that CT scanning of roots and canopies is highly demanding in terms of technology, multidisciplinarity and big-data analysis, to name a few areas of expertise, but eventually, the reward for researchers is directly proportional! PMID:26734022

  16. Pictorial essay: CT scan of appendicitis and its mimics causing right lower quadrant pain

    PubMed Central

    Sharma, Monika; Agrawal, Anjali

    2008-01-01

    CT scanning is widely used in the diagnostic workup of right lower quadrant pain. While appendicitis remains the most frequent cause, a majority of patients referred for suspected appendicitis turn out to have alternative diagnoses or a normal CT study. The purpose of our pictorial essay is to present an overview of the CT findings of appendicitis and its common mimics and to highlight the features that provide clues to alternative diagnoses.

  17. 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.

  18. Acquisition, preprocessing, and reconstruction of ultralow dose volumetric CT scout for organ-based CT scan planning

    SciTech Connect

    Yin, Zhye De Man, Bruno; Yao, Yangyang; Wu, Mingye; Montillo, Albert; Edic, Peter M.; Kalra, Mannudeep

    2015-05-15

    Purpose: Traditionally, 2D radiographic preparatory scan images (scout scans) are used to plan diagnostic CT scans. However, a 3D CT volume with a full 3D organ segmentation map could provide superior information for customized scan planning and other purposes. A practical challenge is to design the volumetric scout acquisition and processing steps to provide good image quality (at least good enough to enable 3D organ segmentation) while delivering a radiation dose similar to that of the conventional 2D scout. Methods: The authors explored various acquisition methods, scan parameters, postprocessing methods, and reconstruction methods through simulation and cadaver data studies to achieve an ultralow dose 3D scout while simultaneously reducing the noise and maintaining the edge strength around the target organ. Results: In a simulation study, the 3D scout with the proposed acquisition, preprocessing, and reconstruction strategy provided a similar level of organ segmentation capability as a traditional 240 mAs diagnostic scan, based on noise and normalized edge strength metrics. At the same time, the proposed approach delivers only 1.25% of the dose of a traditional scan. In a cadaver study, the authors’ pictorial-structures based organ localization algorithm successfully located the major abdominal-thoracic organs from the ultralow dose 3D scout obtained with the proposed strategy. Conclusions: The authors demonstrated that images with a similar degree of segmentation capability (interpretability) as conventional dose CT scans can be achieved with an ultralow dose 3D scout acquisition and suitable postprocessing. Furthermore, the authors applied these techniques to real cadaver CT scans with a CTDI dose level of less than 0.1 mGy and successfully generated a 3D organ localization map.

  19. Micro computed tomography (CT) scanned anatomical gateway to insect pest bioinformatics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An international collaboration to establish an interactive Digital Video Library for a Systems Biology Approach to study the Asian citrus Psyllid and psyllid genomics/proteomics interactions is demonstrated. Advances in micro-CT, digital computed tomography (CT) scan uses X-rays to make detailed pic...

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. Increase in dicentric chromosome formation after a single CT scan in adults.

    PubMed

    Abe, Yu; Miura, Tomisato; Yoshida, Mitsuaki A; Ujiie, Risa; Kurosu, Yumiko; Kato, Nagisa; Katafuchi, Atsushi; Tsuyama, Naohiro; Ohba, Takashi; Inamasu, Tomoko; Shishido, Fumio; Noji, Hideyoshi; Ogawa, Kazuei; Yokouchi, Hiroshi; Kanazawa, Kenya; Ishida, Takashi; Muto, Satoshi; Ohsugi, Jun; Suzuki, Hiroyuki; Ishikawa, Tetsuo; Kamiya, Kenji; Sakai, Akira

    2015-01-01

    Excess risk of leukemia and brain tumors after CT scans in children has been reported. We performed dicentric chromosome assay (DCAs) before and after CT scan to assess effects of low-dose ionizing radiation on chromosomes. Peripheral blood (PB) lymphocytes were collected from 10 patients before and after a CT scan. DCA was performed by analyzing either 1,000 or 2,000 metaphases using both Giemsa staining and centromere-fluorescence in situ hybridization (Centromere-FISH). The increment of DIC formation was compared with effective radiation dose calculated using the computational dosimetry system, WAZA-ARI and dose length product (DLP) in a CT scan. Dicentric chromosome (DIC) formation increased significantly after a single CT scan, and increased DIC formation was found in all patients. A good correlation between the increment of DIC formation determined by analysis of 2,000 metaphases using Giemsa staining and those by 2,000 metaphases using Centromere-FISH was observed. However, no correlation was observed between the increment of DIC formation and the effective radiation dose. Therefore, these results suggest that chromosome cleavage may be induced by one CT scan, and we recommend 2,000 or more metaphases be analyzed in Giemsa staining or Centromere-FISH for DCAs in cases of low-dose radiation exposure. PMID:26349546

  2. Increase in dicentric chromosome formation after a single CT scan in adults

    PubMed Central

    Abe, Yu; Miura, Tomisato; Yoshida, Mitsuaki A.; Ujiie, Risa; Kurosu, Yumiko; Kato, Nagisa; Katafuchi, Atsushi; Tsuyama, Naohiro; Ohba, Takashi; Inamasu, Tomoko; Shishido, Fumio; Noji, Hideyoshi; Ogawa, Kazuei; Yokouchi, Hiroshi; Kanazawa, Kenya; Ishida, Takashi; Muto, Satoshi; Ohsugi, Jun; Suzuki, Hiroyuki; Ishikawa, Tetsuo; Kamiya, Kenji; Sakai, Akira

    2015-01-01

    Excess risk of leukemia and brain tumors after CT scans in children has been reported. We performed dicentric chromosome assay (DCAs) before and after CT scan to assess effects of low-dose ionizing radiation on chromosomes. Peripheral blood (PB) lymphocytes were collected from 10 patients before and after a CT scan. DCA was performed by analyzing either 1,000 or 2,000 metaphases using both Giemsa staining and centromere-fluorescence in situ hybridization (Centromere-FISH). The increment of DIC formation was compared with effective radiation dose calculated using the computational dosimetry system, WAZA-ARI and dose length product (DLP) in a CT scan. Dicentric chromosome (DIC) formation increased significantly after a single CT scan, and increased DIC formation was found in all patients. A good correlation between the increment of DIC formation determined by analysis of 2,000 metaphases using Giemsa staining and those by 2,000 metaphases using Centromere-FISH was observed. However, no correlation was observed between the increment of DIC formation and the effective radiation dose. Therefore, these results suggest that chromosome cleavage may be induced by one CT scan, and we recommend 2,000 or more metaphases be analyzed in Giemsa staining or Centromere-FISH for DCAs in cases of low-dose radiation exposure. PMID:26349546

  3. Osmotic blood-brain barrier modification: clinical documentation by enhanced CT scanning and/or radionuclide brain scanning

    SciTech Connect

    Neuwelt, E.A; Specht, H.D.; Howieson, J.; Haines, J.E.; Bennett, M.J.; Hill, S.A.; Frenkel, E.P.

    1983-10-01

    Results of initial clinical trials of brain tumor chemotherapy after osmotic blood-brain barrier disruption are promising. In general, the procedure is well tolerated. The major complication has been seizures. In this report, data are presented which indicate that the etiology of these seizures is related to the use of contrast agent (meglumine iothalamate) to monitor barrier modification. A series of 19 patients underwent a total of 85 barrier modification procedures. Documentation of barrier disruption was monitored by contrast-enhanced computed tomographic (CT) scanning, radionuclide brain scanning, or a combination of both techniques. In 56 procedures (19 patients) monitored by enhanced CT, seizures occurred a total of 10 times in eight patients. Twenty-three barrier modification procedures (in nine of these 19 patients) documented by nuclear brain scans alone, however, resulted in only one focal motor seizure in each of two patients. Clearly, the radionuclide brain scan does not have the sensitivity and spatial resolution of enhanced CT, but at present it appears safer to monitor barrier modification by this method and to follow tumor growth between barrier modifications by enhanced CT. Four illustrative cases showing methods, problems, and promising results are presented.

  4. Four-dimensional CT scans for treatment planning in stereotactic radiotherapy for stage I lung cancer

    SciTech Connect

    Underberg, Rene; Lagerwaard, Frank J. . E-mail: fj.lagerwaard@vumc.nl; Cuijpers, Johan P.; Slotman, Ben J.; van Soernsen de Koste, John R.; Senan, Suresh

    2004-11-15

    Purpose: Hypofractionated stereotactic radiotherapy (SRT) for Stage I non-small-cell lung cancer requires that meticulous attention be paid toward ensuring optimal target definition. Two computed tomography (CT) scan techniques for defining internal target volumes (ITV) were evaluated. Methods and materials: Ten consecutive patients treated with SRT underwent six 'standard' rapid multislice CT scans to generate an ITV{sub 6CT} and one four-dimensional CT (4DCT) scan that generated volumetric datasets for 10 phases of the respiratory cycle, all of which were used to generate an ITV{sub 4DCT}. Geometric and dosimetric analyses were performed for (1) PTV{sub 4DCT}, derived from the ITV{sub 4DCT} with the addition of a 3-mm margin; (2) PTV{sub 6CT}, derived from the ITV{sub 6CT} with the addition of a 3-mm margin; and (3) 6 PTV{sub 10mm}, derived from each separate GTV{sub 6CT}, to which a three-dimensional margin of 10 mm was added. Results: The ITV{sub 4DCT} was not significantly different from the ITV{sub 6CT} in 8 patients, but was considerably larger in 2 patients whose tumors exhibited the greatest mobility. On average, the ITV{sub 6CT} missed on average 22% of the volume encompassing both ITVs, in contrast to a corresponding mean value of only 8.3% for ITV{sub 4DCT}. Plans based on PTV{sub 4DCT} resulted in coverage of the PTV{sub 6CT} by the 80% isodose in all patients. However, plans based on use of PTV{sub 6CT} led to a mean PTV{sub 4DCT} coverage of only 92.5%, with a minimum of 77.7% and 77.5% for the two most mobile tumors. PTVs derived from a single multislice CT expanded with a margin of 10 mm were on average twice the size of PTVs derived using the other methods, but still led to an underdosing in the two most mobile tumors. Conclusions: Individualized ITVs can improve target definition for SRT of Stage I non-small-cell lung cancer, and use of only a single CT scan with a 10-mm margin is inappropriate. A single 4D scan generates comparable or larger

  5. Co-registration of isotope bone scan with CT scan and MRI in the investigation of spinal pathology.

    PubMed

    Brazenor, Graeme A; Malham, Gregory M; Ballok, Zita E

    2014-09-01

    Image fusion software enables technetium(99m)-methylene diphosphonate (Tc(99m)-MDP) bone scan images to be co-registered with CT scan or MRI, allowing greater anatomical discrimination. We examined the role of bone scan images co-registered with CT scan or MRI in the investigation of patients presenting with axial spinal pain and/or limb pain. One hundred and thirty-nine consecutive patients were examined, and thereafter investigated with CT scan, MRI, and/or dynamic plain films. At this point diagnosis (pathology type and anatomical site) and treatment intention were declared. The co-registered Tc(99m)-MDP bone scan images were then studied, after which diagnosis (pathology type and anatomical site) and treatment intention were re-declared. This data were then analysed to determine whether the addition of co-registered bone scan images resulted in any change in diagnosis or treatment intention. The most significant change in diagnosis was pathology type (10%). Anatomical site changed markedly without overlap of the pre and post-isotope fields in 5%, and with overlap in 10%. Treatment intention had a major change in 3.6% and minor change in 8.6%. In the two groups where there was (i) no obvious pathology after full pre-isotope investigation, or (ii) a spinal fusion under suspicion, addition of the bone scan information led to a major change in the pathology and/or anatomical localisation in 18% and 19%, respectively. The addition of co-registered Tc(99m)-MDP bone scan images offers significant diagnostic assistance, particularly in the difficult diagnostic groups where a failed spinal fusion may be the suspected pain generator, or when no pain generator can otherwise be found. PMID:24798908

  6. Multimodal imaging of the human temporal bone: A comparison of CT and optical scanning techniques

    NASA Astrophysics Data System (ADS)

    Voie, Arne H.; Whiting, Bruce; Skinner, Margaret; Neely, J. Gail; Lee, Kenneth; Holden, Tim; Brunsden, Barry

    2003-10-01

    A collaborative effort between Washington University in St. Louis and Spencer Technologies in Seattle, WA has been undertaken to create a multimodal 3D reconstruction of the human cochlea and vestibular system. The goal of this project is to improve the accuracy of in vivo CT reconstructions of implanted cochleae, and to expand the knowledge of high-resolution anatomical detail provided by orthogonal-plane optical sectioning (OPFOS). At WUSL, computed tomography (CT) images of the cochlea are used to determine the position of cochlear implant electrodes relative to target auditory neurons. The cochlear implant position is determined using pre- and post-operative CT scans. The CT volumes are cross-registered to align the semicircular canals and internal auditory canal, which have a unique configuration in 3-D space. The head of a human body donor was scanned with a clinical CT device, after which the temporal bones were removed, fixed in formalin and trimmed prior to scanning with a laboratory Micro CT scanner. Following CT, the temporal bones were sent to the OPFOS Imaging Lab at Spencer Technologies for a further analysis. 3-D reconstructions of CT and OPFOS imaging modalities were compared, and results are presented. [Work supported by NIDCD Grants R44-03623-5 and R01-00581-13.

  7. The role of PET/CT scanning in radiotherapy planning.

    PubMed

    Jarritt, P H; Carson, K J; Hounsell, A R; Visvikis, D

    2006-09-01

    The introduction of functional data into the radiotherapy treatment planning process is currently the focus of significant commercial, technical, scientific and clinical development. The potential of such data from positron emission tomography (PET) was recognized at an early stage and was integrated into the radiotherapy treatment planning process through the use of image fusion software. The combination of PET and CT in a single system (PET/CT) to form an inherently fused anatomical and functional dataset has provided an imaging modality which could be used as the prime tool in the delineation of tumour volumes and the preparation of patient treatment plans, especially when integrated with virtual simulation. PET imaging typically using 18F-Fluorodeoxyglucose (18F-FDG) can provide data on metabolically active tumour volumes. These functional data have the potential to modify treatment volumes and to guide treatment delivery to cells with particular metabolic characteristics. This paper reviews the current status of the integration of PET and PET/CT data into the radiotherapy treatment process. Consideration is given to the requirements of PET/CT data acquisition with reference to patient positioning aids and the limitations imposed by the PET/CT system. It also reviews the approaches being taken to the definition of functional/tumour volumes and the mechanisms available to measure and include physiological motion into the imaging process. The use of PET data must be based upon a clear understanding of the interpretation and limitations of the functional signal. Protocols for the implementation of this development remain to be defined, and outcomes data based upon clinical trials are still awaited. PMID:16980683

  8. Head CT scan in Iranian minor head injury patients: evaluating current decision rules.

    PubMed

    Sadegh, Robab; Karimialavijeh, Ehsan; Shirani, Farzaneh; Payandemehr, Pooya; Bahramimotlagh, Hooman; Ramezani, Mahtab

    2016-02-01

    The objective of this study is to select one of the seven available clinical decision rules for minor head injury, for managing Iranian patients. This was a prospective cohort study evaluating medium- or high-risk minor head injury patients presenting to the Emergency Department. Patients with minor head trauma who were eligible for brain imaging based on seven available clinical decision rules (National Institute for Health and Clinical Excellence (NICE), National Emergency X-Radiography Utilization Study (NEXUS)-II, Neurotraumatology Committee of the World Federation of Neurosurgical Societies (NCWFNS), New Orleans, American College of Emergency Physicians (ACEP) Guideline, Scandinavian, and Canadian computed tomography (CT) head rule) were selected. Subjects were underwent a non-contrast axial spiral head CT scan. The outcome was defined as abnormal and normal head CT scan. Univariate analysis and stepwise linear regression were applied to show the best combination of risk factors for detecting CT scan abnormalities. Five hundred patients with minor head trauma were underwent brain CT scan. The following criteria were derived by stepwise linear regression: Glasgow Coma Scale (GCS) less than 15, confusion, signs of basal skull fracture, drug history of warfarin, vomiting more than once, loss of consciousness, focal neurologic deficit, and age over 65 years. This model has 86.15 % (75.33-93.45 %) sensitivity and 46.44 % (46.67-51.25 %) specificity in detecting minor head injury patients with CT scan abnormalities (95 % confidence interval). Of seven decision rules, only the Canadian CT Head Rule possesses seven of the eight high-risk factors associated with abnormal head CT results which were identified by this study. This study underlines the Canadian CT Head Rule's utility in Iranian minor head injury patients. Our study encourages researchers to evaluate available guidelines in different communities. PMID:26407978

  9. Predictors of Positive Head CT Scan and Neurosurgical Procedures After Minor Head Trauma

    PubMed Central

    Kisat, Mehreen; Zafar, Syed Nabeel; Latif, Asad; Villegas, Cassandra V.; Efron, David T.; Stevens, Kent A.; Haut, Elliott R; Schneider, Eric B.; Zafar, Hasnain; Haider, Adil H.

    2012-01-01

    Background There continues to be an ongoing debate regarding the utility of Head CT scans in patients with a normal Glasgow Coma Scale (GCS) after minor head injury. The objective of this study is to determine patient and injury characteristics that predict a positive head CT scan or need for a Neurosurgical Procedure (NSP) among patients with blunt head injury and a normal GCS. Materials and Methods Retrospective analysis of adult patients in the National Trauma Data Bank who presented to the ED with a history of blunt head injury and a normal GCS of 15. The primary outcomes were a positive head CT scan or a NSP. Multivariate logistic regression controlling for patient and injury characteristics was used to determine predictors of each outcome. Results Out of a total of 83,566 patients, 24,414 (29.2%) had a positive head CT scan and 3,476 (4.2%) underwent a NSP. Older patients and patients with a history of fall (as compared to a motor vehicle crash) were more likely to have a positive finding on a head CT scan. Male patients, African-Americans (as compared to Caucasians) and those who presented with a fall were more likely to have a NSP. Conclusions Older age, male gender, ethnicity and mechanism of injury are significant predictors of a positive finding on head CT scans and the need for neurosurgical procedures. This study highlights patient and injury specific characteristics that may help in identifying patients with supposedly minor head injury who will benefit from a head CT scan. PMID:21872271

  10. CT of multiple sclerosis: reassessment of delayed scanning with high doses of contrast material

    SciTech Connect

    Spiegel, S.M.; Vinuela, F.; Fox, A.J.; Pelz, D.M.

    1985-09-01

    A prospective study involving 87 patients was carried out to evaluate the necessity for a high dose of contrast material in addition to delayed computed tomographic (CT) scanning for optimal detection of the lesions of multiple sclerosis in the brain. In patients with either clinically definite multiple sclerosis or laboratory-supported definite multiple sclerosis, CT scans were obtained with a uniform protocol. Lesions consistent with multiple sclerosis were demonstrated on the second scan in 54 patients. In 36 of these 54 patients, the high-dose delayed scan added information. These results are quite similar to those of a previous study from this institution using different patients, in whom the second scan was obtained immediately after the bolus injection of contrast material containing 40 g of organically bound iodine. The lack of real difference in the results of the two studies indicate that the increased dose, not just the delay in scanning, is necessary for a proper study.

  11. Application of offset-CT scanning to the inspection of high power feeder lines and connections

    NASA Astrophysics Data System (ADS)

    Schneberk, Daniel; Maziuk, Robert; Soyfer, Boris; Shashishekhar, N.; Alreja, Rahul

    2016-02-01

    VJT is developing techniques and scanning methods for the in-situ Radiographic and Computed Tomographic inspection of underground high-power feeder cables. The goals for the inspection are to measure the 3D state of the cables and the cable-connections. Recent in-situ Digital Radiographic inspections performed by VJT have demonstrated the value of NDE inspection information for buried power lines. These NDE data have raised further questions as to the exact state of the cables and connections and pointed to the need for more 3D information of the type provided by volumetric CT scanning. VJT is pursuing a three phased approach to address the many issues involved in this type of inspection: 1) develop a high-power feeder-cable test-bed CT scanner, 2) acquire scans on underground feeder pipes that have been removed from service, and 3) from the work in 1) and 2) develop limited-angle CT scanning methods for extending in-situ Digital Radiography to volumetric CT measurements. To this end, VJT has developed and fielded a high-energy test-bed Gantry-type CT scanner (the source and detector move around the object) with a number of important properties. First, the geometry of the gantry-scans can be configured to match the techniques used in the in-situ radiographic inspection. The same X-ray source is employed as in portable Radiographic inspections, a 7.5 MeV Betatron coupled to a Perkin-Elmer Amorphous Silicon detector. Offset-CT scanning is employed as the high-power feeder line assembly is larger than the detector. A description of this scanner and the scan geometry will be presented showing the connection to in-situ radiography. Results from the CT scans of high-power feeder-cable specimens removed from service will be presented with a focus on the inspection potential of volumetric CT data on these assemblies. An evaluation of the scan performance properties of these data compared to the spectrum of life-cycle inspection issues will be presented. Continuing and

  12. Scan-rescan reproducibility of CT densitometric measures of emphysema

    NASA Astrophysics Data System (ADS)

    Chong, D.; van Rikxoort, E. M.; Kim, H. J.; Goldin, J. G.; Brown, M. S.

    2011-03-01

    This study investigated the reproducibility of HRCT densitometric measures of emphysema in patients scanned twice one week apart. 24 emphysema patients from a multicenter study were scanned at full inspiration (TLC) and expiration (RV), then again a week later for four scans total. Scans for each patient used the same scanner and protocol, except for tube current in three patients. Lung segmentation with gross airway removal was performed on the scans. Volume, weight, mean lung density (MLD), relative area under -950HU (RA-950), and 15th percentile (PD-15) were calculated for TLC, and volume and an airtrapping mask (RA-air) between -950 and -850HU for RV. For each measure, absolute differences were computed for each scan pair, and linear regression was performed against volume difference in a subgroup with volume difference <500mL. Two TLC scan pairs were excluded due to segmentation failure. The mean lung volumes were 5802 +/- 1420mL for TLC, 3878 +/- 1077mL for RV. The mean absolute differences were 169mL for TLC volume, 316mL for RV volume, 14.5g for weight, 5.0HU for MLD, 0.66p.p. for RA-950, 2.4HU for PD-15, and 3.1p.p. for RA-air. The <500mL subgroup had 20 scan pairs for TLC and RV. The R2 values were 0.8 for weight, 0.60 for MLD, 0.29 for RA-950, 0.31 for PD-15, and 0.64 for RA-air. Our results indicate that considerable variability exists in densitometric measures over one week that cannot be attributed to breathhold or physiology. This has implications for clinical trials relying on these measures to assess emphysema treatment efficacy.

  13. Quantification of emphysema severity by histogram analysis of CT scans.

    PubMed

    Mendonça, Paulo R S; Padfield, Dirk R; Ross, James C; Miller, James V; Dutta, Sandeep; Gautham, Sardar Mal

    2005-01-01

    Emphysema is characterized by the destruction and over distension of lung tissue, which manifest on high resolution computer tomography (CT) images as regions of low attenuation. Typically, it is diagnosed by clinical symptoms, physical examination, pulmonary function tests, and X-ray and CT imaging. In this paper we discuss a quantitative imaging approach to analyze emphysema which employs low-level segmentations of CT images that partition the data into perceptually relevant regions. We constructed multi-dimensional histograms of feature values computed over the image segmentation. For each region in the segmentation, we derive a rich set of feature measurements. While we can use any combination of physical and geometric features, we found that limiting the scope to two features - the mean attenuation across a region and the region area - is effective. The subject histogram is compared to a set of canonical histograms representative of various stages of emphysema using the Earth Mover's Distance metric. Disease severity is assigned based on which canonical histogram is most similar to the subject histogram. Experimental results with 81 cases of emphysema at different stages of disease progression show good agreement against the reading of an expert radiologist. PMID:16685912

  14. Investigation of ultra low-dose scans in the context of quantum-counting clinical CT

    NASA Astrophysics Data System (ADS)

    Weidinger, T.; Buzug, T. M.; Flohr, T.; Fung, G. S. K.; Kappler, S.; Stierstorfer, K.; Tsui, B. M. W.

    2012-03-01

    In clinical computed tomography (CT), images from patient examinations taken with conventional scanners exhibit noise characteristics governed by electronics noise, when scanning strongly attenuating obese patients or with an ultra-low X-ray dose. Unlike CT systems based on energy integrating detectors, a system with a quantum counting detector does not suffer from this drawback. Instead, the noise from the electronics mainly affects the spectral resolution of these detectors. Therefore, it does not contribute to the image noise in spectrally non-resolved CT images. This promises improved image quality due to image noise reduction in scans obtained from clinical CT examinations with lowest X-ray tube currents or obese patients. To quantify the benefits of quantum counting detectors in clinical CT we have carried out an extensive simulation study of the complete scanning and reconstruction process for both kinds of detectors. The simulation chain encompasses modeling of the X-ray source, beam attenuation in the patient, and calculation of the detector response. Moreover, in each case the subsequent image preprocessing and reconstruction is modeled as well. The simulation-based, theoretical evaluation is validated by experiments with a novel prototype quantum counting system and a Siemens Definition Flash scanner with a conventional energy integrating CT detector. We demonstrate and quantify the improvement from image noise reduction achievable with quantum counting techniques in CT examinations with ultra-low X-ray dose and strong attenuation.

  15. Answers to Common Questions About the Use and Safety of CT Scans.

    PubMed

    McCollough, Cynthia H; Bushberg, Jerrold T; Fletcher, Joel G; Eckel, Laurence J

    2015-10-01

    Articles in the scientific literature and lay press over the past several years have implied that computed tomography (CT) may cause cancer and that physicians and patients must exercise caution in its use. Although there is broad agreement on the latter point--unnecessary medical tests of any type should always be avoided--there is considerable controversy surrounding the question of whether, or to what extent, CT scans can lead to future cancers. Although the doses used in CT are higher than those used in conventional radiographic examinations, they are still 10 to 100 times lower than the dose levels that have been reported to increase the risk of cancer. Despite the fact that at the low doses associated with a CT scan the risk either is too low to be convincingly demonstrated or does not exist, the magnitude of the concern among patients and some medical professionals that CT scans increase cancer risk remains unreasonably high. In this article, common questions about CT scanning and radiation are answered to provide physicians with accurate information on which to base their medical decisions and respond to patient questions. PMID:26434964

  16. Motion artifacts in CT scans: a study by computer simulation and mechanical phantom

    NASA Astrophysics Data System (ADS)

    Tien, Der-Chi; Lung, Jen-Kuang; Liao, Chih-Yu; Yong, Tung-Che; Hsu, Chung-Hsien; Liao, Chih-Chiang; Wu, Ren-Hong; Tseng, Kuo-Hsiung; Tsung, Tsing-Tshih

    2008-11-01

    Computed tomography (CT) is one of the most important tools in the diagnosis of thoracic tumors. However, during the scanning process, respiratory motion causes changes in the position and shape of the tumor, creating motion artifacts in the CT scan. This can lead to misdiagnosis of the size and position of the tumor, and can affect the effectiveness of treatment. This study develops a computer model of the movement of the thorax, and simulates the movement of a lung tumor caused by breathing during a CT scan. We show that adjusting the CT slice thickness is sufficient to determine the center of displacement and maximum displacement of a tumor during normal breathing. This model can be applied in the clinical diagnostic use of CT equipment. It will assist in finding the position of lung tumors from motion artifacts in CT scans. The target margin for treatment can thus be defined more accurately, so that appropriate doses of radiation can be applied to the target area, and irradiation of healthy tissue avoided.

  17. Profile of CT scan output dose in axial and helical modes using convolution

    NASA Astrophysics Data System (ADS)

    Anam, C.; Haryanto, F.; Widita, R.; Arif, I.; Dougherty, G.

    2016-03-01

    The profile of the CT scan output dose is crucial for establishing the patient dose profile. The purpose of this study is to investigate the profile of the CT scan output dose in both axial and helical modes using convolution. A single scan output dose profile (SSDP) in the center of a head phantom was measured using a solid-state detector. The multiple scan output dose profile (MSDP) in the axial mode was calculated using convolution between SSDP and delta function, whereas for the helical mode MSDP was calculated using convolution between SSDP and the rectangular function. MSDPs were calculated for a number of scans (5, 10, 15, 20 and 25). The multiple scan average dose (MSAD) for differing numbers of scans was compared to the value of CT dose index (CTDI). Finally, the edge values of MSDP for every scan number were compared to the corresponding MSAD values. MSDPs were successfully generated by using convolution between a SSDP and the appropriate function. We found that CTDI only accurately estimates MSAD when the number of scans was more than 10. We also found that the edge values of the profiles were 42% to 93% lower than that the corresponding MSADs.

  18. Impact of low-dose CT scan in dual timepoint investigations: a phantom study

    NASA Astrophysics Data System (ADS)

    Micheelsen, M. A.; Jensen, M.

    2011-09-01

    Dual timepoint FDG takeup investigations have a potential for separating malignant lymph nodes from non-malignant in certain cases of suspected lung cancer. One hour seems to be the optimal time interval between the two scans (50-120 min). Many of the new PET scanners benefit from image fusion with a CT image and also use the CT for attenuation correction. In any practical hospital setting, 1 hour is too long to occupy the scanner bed and a second CT procedure thus becomes necessary. This study tries to validate to what extent the dose/quality of the second CT scan can be lowered, without compromising attenuation correction, lesion detection and quantification. Using a standard NEMA phantom with the GE Discovery PET/CT scanner, taken in and out between scan sessions, we have tried to find the minimal CT dose necessary for the second scan while still reaching tissue activity quantification within predetermined error limits. For a hot sphere to background activity concentration ratio of 1:5, the average uptake (normalised by the time corrected input activity concentration) in a sphere of 6 cm3 was found to be 0.90 ± 0.08 for the standard scan, yielding a dose of 5.5 mGy, and 0.90 ± 0.14 for a scan with lowest possible mAs product and lowest possible kV, yielding a dose of 0.65 mGy. With an insignificant increase in the uncertainty in the uptake measurement, we can get an order of magnitude reduction for the CT dose.

  19. Feasibility of iodine contrast enhanced CT-scan during a 18F-fluorodeoxyglucose Positron Emission Tomography

    NASA Astrophysics Data System (ADS)

    Houzard, C.; Tychyj, C.; Morelec, I.; Ricard, F.; Got, P.; Cotton, F.; Giammarile, F.; Maintas, D.

    2009-06-01

    OBJECTIVE: this prospective study evaluates the feasibility in current clinical practice of contrast enhanced CT-scan for diagnosis purpose, performed during 18FDG PET-CT study with a PET/CT tomography. METHOD: 25 patients underwent FDG imaging for lymphoma staging. The PET scan was done immediately after the usual low dose CT (lCT). A second CT scan was consequently acquired, by using classical diagnosis CT parameters (dCT) and iodinated contrast. For each patient, all CT attenuation correction (CTAC) PET images were visually compared. Density in Hounsfield units (HU) and maximum Standardized Uptake Value (SUVmax) were then measured on different organs and up to 5 specific lymphoma localizations (total of 294 measurements). RESULTS: Visual analysis was similar for the 2 modalities, without discordant interpretation for the pathologic sites. SUVmax means and standard deviation of each organ for lCTAC and dCTAC were comparable. The equation of the fitted multiple linear regression model was: dCT=0.0748191 + 1.17024*lCT (98.71%; p < 0.01). CONCLUSION: These first results allow the use of injected CT scan, before the PET scan acquisition for lymphoma staging with this PET-CT scan, not affected by the height atomic number and elevated density. A great benefit is therefore obtained on diagnostic, logistic and radioprotection purposes.

  20. Pancreas tumor model in rabbit imaged by perfusion CT scans

    NASA Astrophysics Data System (ADS)

    Gunn, Jason; Tichauer, Kenneth; Moodie, Karen; Kane, Susan; Hoopes, Jack; Stewart, Errol E.; Hadway, Jennifer; Lee, Ting-Yim; Pereira, Stephen P.; Pogue, Brian W.

    2013-03-01

    The goal of this work was to develop and validate a pancreas tumor animal model to investigate the relationship between photodynamic therapy (PDT) effectiveness and photosensitizer drug delivery. More specifically, this work lays the foundation for investigating the utility of dynamic contrast enhanced blood perfusion imaging to be used to inform subsequent PDT. A VX2 carcinoma rabbit cell line was grown in the tail of the pancreas of three New Zealand White rabbits and approximately 3-4 weeks after implantation the rabbits were imaged on a CT scanner using a contrast enhanced perfusion protocol, providing parametric maps of blood flow, blood volume, mean transit time, and vascular permeability surface area product.

  1. CT Scans of Cores Metadata, Barrow, Alaska 2015

    DOE Data Explorer

    Katie McKnight; Tim Kneafsey; Craig Ulrich

    2015-03-11

    Individual ice cores were collected from Barrow Environmental Observatory in Barrow, Alaska, throughout 2013 and 2014. Cores were drilled along different transects to sample polygonal features (i.e. the trough, center and rim of high, transitional and low center polygons). Most cores were drilled around 1 meter in depth and a few deep cores were drilled around 3 meters in depth. Three-dimensional images of the frozen cores were constructed using a medical X-ray computed tomography (CT) scanner. TIFF files can be uploaded to ImageJ (an open-source imaging software) to examine soil structure and densities within each core.

  2. CT Hounsfield Numbers of Soft Tissues on Unenhanced Abdominal CT Scans: Variability Between Two Different Manufacturers’ MDCT Scanners

    PubMed Central

    Lamba, Ramit; McGahan, John P.; Corwin, Michael T.; Li, Chin-Shang; Tran, Tien; Seibert, J. Anthony; Boone, John M.

    2016-01-01

    OBJECTIVE The purpose of this study is to determine whether Hounsfield numbers of soft tissues on unenhanced abdominal CT of the same patient vary on repeat scans done on two different manufacturers’ MDCT scanners. MATERIALS AND METHODS A database search was performed to identify patients older than 18 years who underwent unenhanced CT of the abdomen and pelvis performed both on a Volume CT (GE Healthcare) and a Definition AS Plus (Siemens Healthcare) 64-MDCT scanner within 12 months of each other. After excluding those patients for whom Hounsfield unit measurements would be affected by mitigating factors, 48 patients (mean age, 58.8 years) were identified. Hounsfield unit measurements were obtained in nine different soft-tissue anatomic locations on each scan, and the location of these sites was kept identical on each scan pair. Data were analyzed to evaluate Hounsfield unit differences between these scanners. RESULTS In general, there was a low consistency in the Hounsfield unit measurements for each of these sites on scans obtained by the two scanners, with the subcutaneous fat in the left posterolateral flank showing the lowest correlation (intraclass correlation coefficient, 0.198). There were differences in the Hounsfield unit measurements obtained in all anatomic sites on scans obtained by both scanners. Mean Hounsfield unit measurements obtained on the Definition AS Plus scanner were lower than those obtained on the Volume CT scanner, with the intriguing exception of the anterior midline subcutaneous fat Hounsfield unit measurements, which were higher on the Definition AS Plus scanner. All differences were statistically significant (p < 0.05). CONCLUSION Hounsfield unit measurements for unenhanced abdominal soft tissues of the same patient vary between scanners of two common MDCT manufacturers. PMID:25341139

  3. What to do when a smoker's CT scan is "normal"?: Implications for lung cancer screening.

    PubMed

    Zurawska, Joanna H; Jen, Rachel; Lam, Stephen; Coxson, Harvey O; Leipsic, Jonathon; Sin, Don D

    2012-05-01

    Lung cancer is the leading cause of cancer-related mortality in the United States and around the world. There are > 90 million current and ex-smokers in the United States who are at increased risk of lung cancer. The published data from the National Lung Screening Trial (NLST) suggest that yearly screening with low-dose thoracic CT scan in heavy smokers can reduce lung cancer mortality by 20% and all-cause mortality by 7%. However, to implement this program nationwide using the NLST inclusion and exclusion criteria would be extremely expensive, with CT scan costs alone > $2 billion per annum. In this article, we offer a possible low-cost strategy to risk-stratify smokers on the basis of spirometry measurements and emphysema scoring by radiologists on CT scans. PMID:22553261

  4. Construction of mouse phantoms from segmented CT scan data for radiation dosimetry studies

    NASA Astrophysics Data System (ADS)

    Welch, D.; Harken, A. D.; Randers-Pehrson, G.; Brenner, D. J.

    2015-05-01

    We present the complete construction methodology for an anatomically accurate mouse phantom made using materials which mimic the characteristics of tissue, lung, and bone for radiation dosimetry studies. Phantoms were constructed using 2 mm thick slices of tissue equivalent material which was precision machined to clear regions for insertion of lung and bone equivalent material where appropriate. Images obtained using a 3D computed tomography (CT) scan clearly indicate regions of tissue, lung, and bone that match their position within the original mouse CT scan. Additionally, radiographic films are used with the phantom to demonstrate dose mapping capabilities. The construction methodology presented here can be quickly and easily adapted to create a phantom of any specific small animal given a segmented CT scan of the animal. These physical phantoms are a useful tool to examine individual organ dose and dosimetry within mouse systems that are complicated by density inhomogeneity due to bone and lung regions.

  5. Construction of mouse phantoms from segmented CT scan data for radiation dosimetry studies

    PubMed Central

    Welch, D; Harken, A D; Randers-Pehrson, G; Brenner, D J

    2015-01-01

    We present the complete construction methodology for an anatomically accurate mouse phantom made using materials which mimic the characteristics of tissue, lung, and bone for radiation dosimetry studies. Phantoms were constructed using 2 mm thick slices of tissue equivalent material which was precision machined to clear regions for insertion of lung and bone equivalent material where appropriate. Images obtained using a 3D computed tomography (CT) scan clearly indicate regions of tissue, lung, and bone that match their position within the original mouse CT scan. Additionally, radiographic films are used with the phantom to demonstrate dose mapping capabilities. The construction methodology presented here can be quickly and easily adapted to create a phantom of any specific small animal given a segmented CT scan of the animal. These physical phantoms are a useful tool to examine individual organ dose and dosimetry within mouse systems that are complicated by density inhomogeneity due to bone and lung regions. PMID:25860401

  6. Radiation dose calculations for CT scans with tube current modulation using the approach to equilibrium function

    SciTech Connect

    Li, Xinhua; Zhang, Da; Liu, Bob

    2014-11-01

    Purpose: The approach to equilibrium function has been used previously to calculate the radiation dose to a shift-invariant medium undergoing CT scans with constant tube current [Li, Zhang, and Liu, Med. Phys. 39, 5347–5352 (2012)]. The authors have adapted this method to CT scans with tube current modulation (TCM). Methods: For a scan with variable tube current, the scan range was divided into multiple subscan ranges, each with a nearly constant tube current. Then the dose calculation algorithm presented previously was applied. For a clinical CT scan series that presented tube current per slice, the authors adopted an efficient approach that computed the longitudinal dose distribution for one scan length equal to the slice thickness, which center was at z = 0. The cumulative dose at a specific point was a summation of the contributions from all slices and the overscan. Results: The dose calculations performed for a total of four constant and variable tube current distributions agreed with the published results of Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)]. For an abdomen/pelvis scan of an anthropomorphic phantom (model ATOM 701-B, CIRS, Inc., VA) on a GE Lightspeed Pro 16 scanner with 120 kV, N × T = 20 mm, pitch = 1.375, z axis current modulation (auto mA), and angular current modulation (smart mA), dose measurements were performed using two lines of optically stimulated luminescence dosimeters, one of which was placed near the phantom center and the other on the surface. Dose calculations were performed on the central and peripheral axes of a cylinder containing water, whose cross-sectional mass was about equal to that of the ATOM phantom in its abdominal region, and the results agreed with the measurements within 28.4%. Conclusions: The described method provides an effective approach that takes into account subject size, scan length, and constant or variable tube current to evaluate CT dose to a shift-invariant medium. For a clinical CT scan

  7. Estimating Radiation Dose Metrics for Patients Undergoing Tube Current Modulation CT Scans

    NASA Astrophysics Data System (ADS)

    McMillan, Kyle Lorin

    Computed tomography (CT) has long been a powerful tool in the diagnosis of disease, identification of tumors and guidance of interventional procedures. With CT examinations comes the concern of radiation exposure and the associated risks. In order to properly understand those risks on a patient-specific level, organ dose must be quantified for each CT scan. Some of the most widely used organ dose estimates are derived from fixed tube current (FTC) scans of a standard sized idealized patient model. However, in current clinical practice, patient size varies from neonates weighing just a few kg to morbidly obese patients weighing over 200 kg, and nearly all CT exams are performed with tube current modulation (TCM), a scanning technique that adjusts scanner output according to changes in patient attenuation. Methods to account for TCM in CT organ dose estimates have been previously demonstrated, but these methods are limited in scope and/or restricted to idealized TCM profiles that are not based on physical observations and not scanner specific (e.g. don't account for tube limits, scanner-specific effects, etc.). The goal of this work was to develop methods to estimate organ doses to patients undergoing CT scans that take into account both the patient size as well as the effects of TCM. This work started with the development and validation of methods to estimate scanner-specific TCM schemes for any voxelized patient model. An approach was developed to generate estimated TCM schemes that match actual TCM schemes that would have been acquired on the scanner for any patient model. Using this approach, TCM schemes were then generated for a variety of body CT protocols for a set of reference voxelized phantoms for which TCM information does not currently exist. These are whole body patient models representing a variety of sizes, ages and genders that have all radiosensitive organs identified. TCM schemes for these models facilitated Monte Carlo-based estimates of fully

  8. An old enemy not to be forgotten during PET CT scanning of cancer patients: tuberculosis

    PubMed Central

    Sezer, Ahmet; Abali, Hüseyin; Gültepe, Bilge; Koçer, Emrah; Reyhan, Mehmet; Tonyalı, Önder; Özyilkan, Özgür

    2014-01-01

    Aim of the study Positron emission tomography–computed tomography (PET CT) scan is commonly used in current medical oncology practice as an imaging method. In this study we present data from cancer patients who were followed at our clinic and suspected of having tuberculosis during PET CT scanning. After the biopsy, they were diagnosed with concomitant tuberculosis. Material and methods In this study, 14 patients who applied to our clinic and followed up due to cancer, and had PET CT scanning for the preliminary staging or further evaluation, were included. The patients were diagnosed with metastatic or recurrent disease, and their biopsy results revealed tuberculosis. Results The mean age was 57.8 years with SD (standard deviation) 13.1 years and gender distribution of 78.6% (n = 11) females and 21.4% (n = 3) males. None of the patients had tuberculosis in their personal history (0%). Among the patients, 5 (35.7%) were diagnosed with tuberculosis during the preliminary staging, whereas 9 (64.3%) were diagnosed during the follow-up after the treatment. The median time to tuberculosis diagnosis was 11 months (min–max: 3–24 months) after the treatment. The most commonly involved lymph nodes during PET CT scanning were mediastinal in 8 (64.3%), axillary in 3 (21.4%) and para-aortic in 3 (21.4%) patients. The mean SUVmax (maximum standardised uptake value) of lymph node involved by PET CT scanning was defined as 8.5 (SD 2.6). Conclusions Despite all improvements in modern medicine, tuberculosis is still a serious public health problem. It should always be considered in differential diagnosis while evaluating PET CT scanning results of cancer patients, because it may cause false positive results. PMID:27358601

  9. Lung function in silica-exposed workers. A relationship to disease severity assessed by CT scan.

    PubMed

    Bégin, R; Ostiguy, G; Cantin, A; Bergeron, D

    1988-09-01

    To investigate the relationship of lung function, airflow limitation, and lung injury in silica-exposed workers, we analyzed the clinical, functional, and radiologic data of 94 long-term workers exposed in the granite industry or in foundries. The subjects were divided into four subsets based on chest roentgenogram and CT scan of the thorax: group 1 consisted of 21 subjects with category 0 chest roentgenogram and category 0 CT scan; group 2, 28 subjects with category E 1 on both chest roentgenogram and CT scan; group 3, 18 subjects with category E 1 on chest roentgenogram but with coalescence or conglomeration or both seen only on CT scan; and group 4, 27 subjects with category E 1 and coalescence or conglomeration or both on roentgenogram and CT scan. The groups did not differ in terms of age, height, cigarette smoking, or years of exposure. Lung volumes were significantly reduced only in group 4 (p less than 0.05). Lung compliance, diffusion capacity, and the rest-exercise P(A-a)O2 gradient were reduced in groups 3 and 4 (p less than 0.05). Expiratory flow rates were significantly reduced in groups 2, 3, and 4, with the lowest values in group 4. The expiratory flow rates in group 3 were significantly lower in group 3 than in group 2. These results support the concept that airflow in silica-exposed workers is significantly reduced when the disease is detectable on simple chest roentgenogram; coalescence or conglomeration or both on chest roentgenogram or CT scan is associated with significant loss of lung volumes, gas exchange function, and increased airflow obstruction. PMID:3409733

  10. Patient willingness and barriers to receiving a CT scan for lung cancer screening.

    PubMed

    Delmerico, Jennifer; Hyland, Andrew; Celestino, Paula; Reid, Mary; Cummings, K Michael

    2014-06-01

    CT scans are becoming a more common method for detecting lung cancers at an earlier, potentially more curable, stage of disease. There is currently little data on attitudes and beliefs about screening for lung cancer. This paper presents the results of a 2011 survey of adult current and former smokers that queried about past use of CT scanning and reasons for having or not having the screening done. A random-digit dialed telephone survey was administered to a representative sample of 1290 US adults. Logistic regression analyses were used to examine the correlates of having the test while controlling for the covariates. A total of 13.4% (n = 45) of the sample had ever had a CT scan to detect lung cancer. Of current smokers, 14.6% had received a CT scan, as compared with 12.7% of former smokers. The oldest age group (55+) was significantly more likely to have received a CT scan than the younger age groups. 78.5% of current smokers and 81.4% of former smokers indicated willingness to get the test if advised to do so by their doctor. Among those who said they were not willing to get screened, lack of insurance coverage was cited by 33% of current smokers and 25% of former smokers. Additionally, 33% of current smokers were afraid to find out whether they had cancer. The main barrier to CT scanning for lung cancer is likely to be insurance coverage for the test, which would be a burden for those on limited and fixed incomes. Next steps should include further research into the effect of increased public education about the availability, risks, benefits and barriers to lung cancer screening. PMID:24674155

  11. Clinical evaluation of semi-automatic landmark-based lesion tracking software for CT-scans

    PubMed Central

    2014-01-01

    Background To evaluate a semi-automatic landmark-based lesion tracking software enabling navigation between RECIST lesions in baseline and follow-up CT-scans. Methods The software automatically detects 44 stable anatomical landmarks in each thoraco/abdominal/pelvic CT-scan, sets up a patient specific coordinate-system and cross-links the coordinate-systems of consecutive CT-scans. Accuracy of the software was evaluated on 96 RECIST lesions (target- and non-target lesions) in baseline and follow-up CT-scans of 32 oncologic patients (64 CT-scans). Patients had to present at least one thoracic, one abdominal and one pelvic RECIST lesion. Three radiologists determined the deviation between lesions’ centre and the software’s navigation result in consensus. Results The initial mean runtime of the system to synchronize baseline and follow-up examinations was 19.4 ± 1.2 seconds, with subsequent navigation to corresponding RECIST lesions facilitating in real-time. Mean vector length of the deviations between lesions’ centre and the semi-automatic navigation result was 10.2 ± 5.1 mm without a substantial systematic error in any direction. Mean deviation in the cranio-caudal dimension was 5.4 ± 4.0 mm, in the lateral dimension 5.2 ± 3.9 mm and in the ventro-dorsal dimension 5.3 ± 4.0 mm. Conclusion The investigated software accurately and reliably navigates between lesions in consecutive CT-scans in real-time, potentially accelerating and facilitating cancer staging. PMID:25609496

  12. Glenoid loosening after total shoulder arthroplasty: an in vitro CT-scan study.

    PubMed

    Gregory, Thomas; Hansen, Ulrich; Taillieu, Fabienne; Baring, Toby; Brassart, Nicolas; Mutchler, Céline; Amis, Andrew; Augereau, Bernard; Emery, Roger

    2009-12-01

    Glenoid fixation failure has only been grossly characterized. This lack of information hinders attempts to improve fixation because of a lack of methodologies for detecting and monitoring fixation failure. Our goal was twofold: to collect detailed data of glenoid fixation fracture, and to investigate computed tomography (CT)-scanning as a tool for investigations of fixation failure. Six cadaver scapulas and six bone-substitute specimens were cyclically loaded and CT-scanned at clinical settings after 0, 1,000, 5,000, 10,000, 30,000, 50,000 and 70,000 load cycles. The fixation status was evaluated by inspection of the scans. After 70,000 cycles, the specimens were sectioned, and the fixation inspected by microscopy. The results of the microscopy analysis were compared to the CT-scan analysis. Fracture of the glenoid fixation initiated at the edge of the glenoid rim and propagated towards and around the keel of the implant. The entire process from initiation to complete fracture took place at the polyethylene implant-cement interface, while the cement, the adjacent bone, and the cement-bone interface remained intact. Thus, strengthening the polyethylene-cement interface should improve glenoid fixation. Microscopy results validated the CT methodology, suggesting that the CT technique is reliable. PMID:19472376

  13. High-pitch spiral acquisition: a new scan mode for coronary CT angiography.

    PubMed

    Achenbach, Stephan; Marwan, Mohamed; Schepis, Tiziano; Pflederer, Tobias; Bruder, Herbert; Allmendinger, Thomas; Petersilka, Martin; Anders, Katharina; Lell, Michael; Kuettner, Axel; Ropers, Dieter; Daniel, Werner G; Flohr, Thomas

    2009-01-01

    Coronary CT angiography allows high-quality imaging of the coronary arteries when state-of-the-art CT systems are used. However, radiation exposure has been a concern. We describe a new scan mode that uses a very high-pitch spiral acquisition, "Flash Spiral," which has been developed specifically for low-dose imaging with dual-source CT. The scan mode uses a pitch of 3.2 to acquire a spiral CT data set, while covering the entire volume of the heart in one cardiac cycle. Data acquisition is prospectively triggered by the electrocardiogram and starts in late systole to be completed within one cardiac cycle. Images are reconstructed with a temporal resolution that corresponds to one-quarter of the gantry rotation time. Throughout the data set, subsequent images are reconstructed at later time instants in the cardiac cycle. In a patient with a heart rate of 49 beats/min, the Flash Spiral scan mode was used with a first-generation dual-source CT system and allowed artifact-free visualization of the coronary arteries with a radiation exposure of 1.7 mSv for a 12-cm scan range at 120 kVp tube voltage. PMID:19332343

  14. Overbeaming and overlapping of volume-scan CT with tube current modulation in a 320-detector row CT scanner

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Lan; Chen, Yan-Shi; Lai, Nan-Ku; Chuang, Keh-Shih; Tsai, Hui-Yu

    2014-11-01

    The purpose of this study was to evaluate the performance of volume scan tube current modulation (VS-ATCM) with adaptive iterative dose reduction 3D (AIDR3D) technique in abdomen CT examinations. We scanned an elliptical cone-shaped phantom utilizing AIDR3D technique combined with VS-ATCM mode in a 320-detector row CT scanner. The image noise distributions with conventional filtered back-projction (FBP) technique and those with AIDR3D technique were compared. The radiation dose profile and tube current time product (mAs) in three noise levels of VS-ATCM modes were compared. The radiation beam profiles of five preset scan lengths were measured using Gafchromic film strips to assess the effects of overbeaming and everlapping. The results indicated that the image noises with AIDR3D technique was 13-74% lower than those in FBP technique. The mAs distributions can be a prediction for various abdominal sizes when undergoing a VS-ATCM mode scan. Patients can receive the radiation dose of overbeaming and overlapping during the VS-ATCM mode scans.

  15. Synthetic CT: Simulating low dose single and dual energy protocols from a dual energy scan

    SciTech Connect

    Wang, Adam S.; Pelc, Norbert J.

    2011-10-15

    Purpose: The choice of CT protocol can greatly impact patient dose and image quality. Since acquiring multiple scans at different techniques on a given patient is undesirable, the ability to predict image quality changes starting from a high quality exam can be quite useful. While existing methods allow one to generate simulated images of lower exposure (mAs) from an acquired CT exam, the authors present and validate a new method called synthetic CT that can generate realistic images of a patient at arbitrary low dose protocols (kVp, mAs, and filtration) for both single and dual energy scans. Methods: The synthetic CT algorithm is derived by carefully ensuring that the expected signal and noise are accurate for the simulated protocol. The method relies on the observation that the material decomposition from a dual energy CT scan allows the transmission of an arbitrary spectrum to be predicted. It requires an initial dual energy scan of the patient to either synthesize raw projections of a single energy scan or synthesize the material decompositions of a dual energy scan. The initial dual energy scan contributes inherent noise to the synthesized projections that must be accounted for before adding more noise to simulate low dose protocols. Therefore, synthetic CT is subject to the constraint that the synthesized data have noise greater than the inherent noise. The authors experimentally validated the synthetic CT algorithm across a range of protocols using a dual energy scan of an acrylic phantom with solutions of different iodine concentrations. An initial 80/140 kVp dual energy scan of the phantom provided the material decomposition necessary to synthesize images at 100 kVp and at 120 kVp, across a range of mAs values. They compared these synthesized single energy scans of the phantom to actual scans at the same protocols. Furthermore, material decompositions of a 100/120 kVp dual energy scan are synthesized by adding correlated noise to the initial material

  16. Treatment of Alzheimer Disease With CT Scans: A Case Report.

    PubMed

    Cuttler, Jerry M; Moore, Eugene R; Hosfeld, Victor D; Nadolski, David L

    2016-01-01

    Alzheimer disease (AD) primarily affects older adults. This neurodegenerative disorder is the most common cause of dementia and is a leading source of their morbidity and mortality. Patient care costs in the United States are about 200 billion dollars and will more than double by 2040. This case report describes the remarkable improvement in a patient with advanced AD in hospice who received 5 computed tomography scans of the brain, about 40 mGy each, over a period of 3 months. The mechanism appears to be radiation-induced upregulation of the patient's adaptive protection systems against AD, which partially restored cognition, memory, speech, movement, and appetite. PMID:27103883

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  18. 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

  19. [Fundamental study of helical scanning CT--evaluation of spatial resolution in the longitudinal axis].

    PubMed

    Anno, H; Katada, K; Tsujioka, K; Ida, Y; Ohashi, I; Takeuchi, A; Koga, S

    1992-11-25

    We evaluated spatial resolution in the longitudinal axis with helical scanning CT using a fourth-generation fast CT scanner. We made a phantom by stringing acrylic balls (65 mm phi x 8 and 9 mm phi x 6). The acquired images were processed by MPR and assessed visually to evaluate axis resolution. With the conventional scanning method, the partial volume effect varied with the starting position, but helical scanning was able to reconstruct high-resolution images using continuous raw data. During helical scanning, axis resolution varied depending on the slice width and sliding speed of the couch top. Even if the sliding speed was kept constant at 4 mm/sec, axis resolution was superior with a slice width of 2 mm than with one of 5 mm. PMID:1465334

  20. The Impact of Sources of Variability on Parametric Response Mapping of Lung CT Scans

    PubMed Central

    Boes, Jennifer L.; Bule, Maria; Hoff, Benjamin A.; Chamberlain, Ryan; Lynch, David A.; Stojanovska, Jadranka; Martinez, Fernando J.; Han, Meilan K.; Kazerooni, Ella A.; Ross, Brian D.; Galbán, Craig J.

    2015-01-01

    Parametric response mapping (PRM) of inspiration and expiration computed tomography (CT) images improves the radiological phenotyping of chronic obstructive pulmonary disease (COPD). PRM classifies individual voxels of lung parenchyma as normal, emphysematous, or nonemphysematous air trapping. In this study, bias and noise characteristics of the PRM methodology to CT and clinical procedures were evaluated to determine best practices for this quantitative technique. Twenty patients of varying COPD status with paired volumetric inspiration and expiration CT scans of the lungs were identified from the baseline COPD-Gene cohort. The impact of CT scanner manufacturer and reconstruction kernels were evaluated as potential sources of variability in PRM measurements along with simulations to quantify the impact of inspiration/expiration lung volume levels, misregistration, and image spacing on PRM measurements. Negligible variation in PRM metrics was observed when CT scanner type and reconstruction were consistent and inspiration/expiration lung volume levels were near target volumes. CT scanner Hounsfield unit drift occurred but remained difficult to ameliorate. Increasing levels of image misregistration and CT slice spacing were found to have a minor effect on PRM measurements. PRM-derived values were found to be most sensitive to lung volume levels and mismatched reconstruction kernels. As with other quantitative imaging techniques, reliable PRM measurements are attainable when consistent clinical and CT protocols are implemented. PMID:26568983

  1. Interactive lung segmentation in abnormal human and animal chest CT scans

    SciTech Connect

    Kockelkorn, Thessa T. J. P. Viergever, Max A.; Schaefer-Prokop, Cornelia M.; Bozovic, Gracijela; Muñoz-Barrutia, Arrate; Rikxoort, Eva M. van; Brown, Matthew S.; Jong, Pim A. de; Ginneken, Bram van

    2014-08-15

    Purpose: Many medical image analysis systems require segmentation of the structures of interest as a first step. For scans with gross pathology, automatic segmentation methods may fail. The authors’ aim is to develop a versatile, fast, and reliable interactive system to segment anatomical structures. In this study, this system was used for segmenting lungs in challenging thoracic computed tomography (CT) scans. Methods: In volumetric thoracic CT scans, the chest is segmented and divided into 3D volumes of interest (VOIs), containing voxels with similar densities. These VOIs are automatically labeled as either lung tissue or nonlung tissue. The automatic labeling results can be corrected using an interactive or a supervised interactive approach. When using the supervised interactive system, the user is shown the classification results per slice, whereupon he/she can adjust incorrect labels. The system is retrained continuously, taking the corrections and approvals of the user into account. In this way, the system learns to make a better distinction between lung tissue and nonlung tissue. When using the interactive framework without supervised learning, the user corrects all incorrectly labeled VOIs manually. Both interactive segmentation tools were tested on 32 volumetric CT scans of pigs, mice and humans, containing pulmonary abnormalities. Results: On average, supervised interactive lung segmentation took under 9 min of user interaction. Algorithm computing time was 2 min on average, but can easily be reduced. On average, 2.0% of all VOIs in a scan had to be relabeled. Lung segmentation using the interactive segmentation method took on average 13 min and involved relabeling 3.0% of all VOIs on average. The resulting segmentations correspond well to manual delineations of eight axial slices per scan, with an average Dice similarity coefficient of 0.933. Conclusions: The authors have developed two fast and reliable methods for interactive lung segmentation in

  2. "Bottle Brush Sign"-Spinal Meningeal Disease on 18F-FDG PET-CT Scan.

    PubMed

    Riaz, Saima; Naz, Fozia; Bashir, Humayun; Niazi, Imran Khalid

    2016-09-01

    A 30-year-old man with a history of stage IV AE diffuse large cell lymphoma of left proximal humerus presented with new onset lower limb weakness at completion of chemotherapy. The F-FDG PET-CT scan showed increased intraspinal uptake from T12 to S1 vertebrae with unique "bottle brush" appearance in keeping with spinal meningeal disease. The leptomeningeal disease was further confirmed on correlative MRI scan. PMID:27405033

  3. Automatic coronary calcium scoring in low-dose non-ECG-synchronized thoracic CT scans

    NASA Astrophysics Data System (ADS)

    Isgum, Ivana; Prokop, Mathias; Jacobs, Peter C.; Gondrie, Martijn J.; Mali, Willem P. Th. M.; Viergever, Max A.; van Ginneken, Bram

    2010-03-01

    This work presents a system for automatic coronary calcium scoring and cardiovascular risk stratification in thoracic CT scans. Data was collected from a Dutch-Belgian lung cancer screening trial. In 121 low-dose, non-ECG synchronized, non-contrast enhanced thoracic CT scans an expert scored coronary calcifications manually. A key element of the proposed algorithm is that the approximate position of the coronary arteries was inferred with a probabilistic coronary calcium atlas. This atlas was created with atlas-based segmentation from 51 scans and their manually identified calcifications, and was registered to each unseen test scan. In the test scans all objects with density above 130 HU were considered candidates that could represent coronary calcifications. A statistical pattern recognition system was designed to classify these candidates using features that encode their spatial position relative to the inferred position of the coronaries obtained from the atlas registration. In addition, size and texture features were computed for all candidates. Two consecutive classifiers were used to label each candidate. The system was trained with 35 and tested with another 35 scans. The detected calcifications were quantified and cardiovascular risk was determined for each subject. The system detected 71% of coronary calcifications with an average of 0.9 false positive objects per scan. Cardiovascular risk category was correctly assigned to 29 out of 35 subjects (83%). Five scans (14%) were one category off, and only one scan (3%) was two categories off. We conclude that automatic assessment of the cardiovascular risk from low-dose, non-ECG synchronized thoracic CT scans appears feasible.

  4. Multienergy CT acquisition and reconstruction with a stepped tube potential scan

    SciTech Connect

    Shen, Le; Xing, Yuxiang

    2015-01-15

    Purpose: Based on an energy-dependent property of matter, one may obtain a pseudomonochromatic attenuation map, a material composition image, an electron-density distribution, and an atomic number image using a dual- or multienergy computed tomography (CT) scan. Dual- and multienergy CT scans broaden the potential of x-ray CT imaging. The development of such systems is very useful in both medical and industrial investigations. In this paper, the authors propose a new dual- and multienergy CT system design (segmental multienergy CT, SegMECT) using an innovative scanning scheme that is conveniently implemented on a conventional single-energy CT system. The two-step-energy dual-energy CT can be regarded as a special case of SegMECT. A special reconstruction method is proposed to support SegMECT. Methods: In their SegMECT, a circular trajectory in a CT scan is angularly divided into several arcs. The x-ray source is set to a different tube voltage for each arc of the trajectory. Thus, the authors only need to make a few step changes to the x-ray energy during the scan to complete a multienergy data acquisition. With such a data set, the image reconstruction might suffer from severe limited-angle artifacts if using conventional reconstruction methods. To solve the problem, they present a new prior-image-based reconstruction technique using a total variance norm of a quotient image constraint. On the one hand, the prior extracts structural information from all of the projection data. On the other hand, the effect from a possibly imprecise intensity level of the prior can be mitigated by minimizing the total variance of a quotient image. Results: The authors present a new scheme for a SegMECT configuration and establish a reconstruction method for such a system. Both numerical simulation and a practical phantom experiment are conducted to validate the proposed reconstruction method and the effectiveness of the system design. The results demonstrate that the proposed Seg

  5. NOTE: An anatomically shaped lower body model for CT scanning of cadaver femurs

    NASA Astrophysics Data System (ADS)

    Tanck, Esther; Deenen, J. C. W.; Huisman, Henk Jan; Kooloos, Jan G.; Huizenga, Henk; Verdonschot, Nico

    2010-01-01

    Bone specific, CT-based finite element (FE) analyses have great potential to accurately predict the fracture risk of deteriorated bones. However, it has been shown that differences exist between FE-models of femora scanned in a water basin or scanned in situ within the human body, as caused by differences in measured bone mineral densities (BMD). In this study we hypothesized that these differences can be reduced by re-creating the patient CT-conditions by using an anatomically shaped physical model of the lower body. BMD distributions were obtained from four different femora that were scanned under three conditions: (1) in situ within the cadaver body, (2) in a water basin and (3) in the body model. The BMD of the three scanning protocols were compared at two locations: proximally, in the trabecular bone of the femoral head, and in the cortical bone of the femoral shaft. Proximally, no significant differences in BMD were found between the in situ scans and the scans in the body model, whereas the densities from the water basin scans were on average 10.8% lower than in situ. In the femoral shaft the differences between the three scanning protocols were insignificant. In conclusion, the body model better approached the in situ situation than a water basin. Future studies can use this body model to mimic patient situations and to develop protocols to improve the performance of the FE-models in actual patients.

  6. Study Finds Small Increase in Cancer Risk after Childhood CT Scans

    Cancer.gov

    A study published in the June 6, 2012, issue of The Lancet shows that radiation exposure from computed tomography (CT) scans in childhood results in very small but increased risks of leukemia and brain tumors in the first decade after exposure.

  7. Intraosseous pneumatocysts of the ilium: findings on radiographs and CT scans

    SciTech Connect

    Ramirez, H.; Blatt, E.S.; Cable, H.F.; McComb, B.L.; Zornoza, J.; Hibri, N.S.

    1984-02-01

    CT scans demonstrated a localized collection of gas adjacent to a normal sacroiliac joint in 5 patients. In each case the lesion was sharply demarcated by a thin sclerotic rim. A benign bone cyst was confirmed histologically in 2 cases. The radiologist should be aware of this appearance so as to avoid invasive procedures based on a misdiagnosis of infection or neoplasm.

  8. Chest CT scanning for clinical suspected thoracic aortic dissection: beware the alternate diagnosis.

    PubMed

    Thoongsuwan, Nisa; Stern, Eric J

    2002-11-01

    The aim of the study was retrospectively to evaluate the spectrum of chest diseases in patients presenting with clinical suspicion of thoracic aortic dissection in the emergency department. We performed a retrospective medical records review of 86 men and 44 women (ages ranging between 23 and 106 years) with clinically suspected aortic dissection, for CT scan findings and final clinical diagnoses dating between January 1996 and September 2001. All images were obtained by using a standard protocol for aortic dissection. We found aortic dissection in 32 patients (24.6%), 22 of which were Stanford classification type A and 10 Stanford type B. In 70 patients (53.9%), chest pain could not be explained by the CT scan findings. However, in 28 patients (21.5%), CT scanning did reveal an alternate diagnosis that, along with the clinical impression, probably explained the patients' presenting symptoms, including: hiatal hernia (7), pneumonia (5), intrathoracic mass (4), pericardial effusion/hemopericardium (3), esophageal mass/rupture (2), aortic aneurysm without dissection (2), pulmonary embolism (2), pleural effusion (1), aortic rupture (1), and pancreatitis (1). In cases where there is clinical suspicion of aortic dissection, CT scan findings of an alternate diagnosis for the presenting symptoms are only slightly less common than the finding of aortic dissection itself. Although the spectrum of findings will vary depending upon your patient population, beware the alternate diagnosis. PMID:15290550

  9. A semi-automated method for hexahedral mesh construction of human vertebrae from CT scans.

    PubMed

    Dai, Yifei; Niebur, Glen L

    2009-10-01

    Generation of finite element (FE) meshes of vertebrae from computed tomography (CT) scans is labour intensive due to their geometric complexity. As such, techniques that simplify creation of meshes of vertebrae are needed to make FE analysis feasible for large studies and clinical applications. Techniques to obtain a geometric representation of bone contours from CT scans of vertebrae and construct a hexahedral mesh from the contours were developed. An automated edge detection technique was developed to identify surface contours of the vertebrae, followed by atlas based B-spline curve fitting to construct curves from the edge points. The method was automatic and robust to missing data, with a controllable degree of smoothing and interpolation. Parametric mapping was then used to generate nodes for each CT slice, which were connected between slices to obtain a hexahedral mesh. This method could be adapted for modelling a variety of orthopaedic structures. PMID:19308870

  10. CT Scan as an Essential Tool in Diagnosis of Non-radiopaque Sialoliths.

    PubMed

    Kalia, Vimal; Kalra, Geeta; Kaur, Supreet; Kapoor, Rajeev

    2015-03-01

    Sialolithiasis is the second most common disease of the salivary glands and the main cause of salivary gland obstruction. Diagnosis of calculi/sialoliths can be made by means of an elaborate history, precise clinical examination and radiographic support. But all sialoliths do not present with predictable signs and symptoms and radiographic appearance. Sialoliths have a variety of manifestations and they may or may not be radiopaque. Non-radiopaque sialoliths are difficult to diagnose radiographically. Although newer techniques like CBCT, CT virtual sialandoscopy and established techniques like sialography, xeroradiography can be useful in selected cases. A regular CT scan is an excellent tool in the diagnosis of a non-radiopaque sialolith and associated salivary gland changes. CT scan should be considered as an important tool of imaging for diagnosis, treatment planning and follow-up of all cases of sialoliths and associated pathologies of the salivary gland. PMID:25838703

  11. Kernohan's Notch: A Forgotten Cause of Hemiplegia—CT Scans Are Useful in This Diagnosis

    PubMed Central

    Panikkath, Deepa; Lim, Sian Yik

    2013-01-01

    Hemiparesis ipsilateral to a cerebral lesion can be a false localizing sign. This is due to midline shift of the midbrain resulting in compression of the contralateral pyramidal fibers on the tough dural reflection tentorium cerebelli. This may result in partial or complete damage to these fibers. Since these fibers are destined to cross in the medulla and innervate the opposite side of the body, this causes hemiparesis ipsilateral to the site of cerebral lesion. Computed tomography (CT) scans have not been used to support the diagnosis of this entity until now. We report a 68-year-old woman with a subdural hematoma who developed ipsilateral hemiparesis without any other explanation (Kernohan's notch). The CT of the head showed evidence of compression of the midbrain contralateral to the hematoma and was useful in the diagnosis. The purpose of this report is to increase the awareness of this presentation and to emphasize the utility of CT scans to support the diagnosis. PMID:24348572

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

    SciTech Connect

    Arvold, Nils D.; Niemierko, Andrzej; Mamon, Harvey J.; Hong, Theodore S.

    2011-08-01

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

  13. "High-precision, reconstructed 3D model" of skull scanned by conebeam CT: Reproducibility verified using CAD/CAM data.

    PubMed

    Katsumura, Seiko; Sato, Keita; Ikawa, Tomoko; Yamamura, Keiko; Ando, Eriko; Shigeta, Yuko; Ogawa, Takumi

    2016-01-01

    Computed tomography (CT) scanning has recently been introduced into forensic medicine and dentistry. However, the presence of metal restorations in the dentition can adversely affect the quality of three-dimensional reconstruction from CT scans. In this study, we aimed to evaluate the reproducibility of a "high-precision, reconstructed 3D model" obtained from a conebeam CT scan of dentition, a method that might be particularly helpful in forensic medicine. We took conebeam CT and helical CT images of three dry skulls marked with 47 measuring points; reconstructed three-dimensional images; and measured the distances between the points in the 3D images with a computer-aided design/computer-aided manufacturing (CAD/CAM) marker. We found that in comparison with the helical CT, conebeam CT is capable of reproducing measurements closer to those obtained from the actual samples. In conclusion, our study indicated that the image-reproduction from a conebeam CT scan was more accurate than that from a helical CT scan. Furthermore, the "high-precision reconstructed 3D model" facilitates reliable visualization of full-sized oral and maxillofacial regions in both helical and conebeam CT scans. PMID:26832374

  14. Analysis of chromosome translocation frequency after a single CT scan in adults.

    PubMed

    Abe, Yu; Miura, Tomisato; Yoshida, Mitsuaki A; Ujiie, Risa; Kurosu, Yumiko; Kato, Nagisa; Katafuchi, Atsushi; Tsuyama, Naohiro; Kawamura, Fumihiko; Ohba, Takashi; Inamasu, Tomoko; Shishido, Fumio; Noji, Hideyoshi; Ogawa, Kazuei; Yokouchi, Hiroshi; Kanazawa, Kenya; Ishida, Takashi; Muto, Satoshi; Ohsugi, Jun; Suzuki, Hiroyuki; Ishikawa, Tetsuo; Kamiya, Kenji; Sakai, Akira

    2016-06-01

    We recently reported an increase in dicentric chromosome (DIC) formation after a single computed tomography (CT) scan (5.78-60.27 mSv: mean 24.24 mSv) and we recommended analysis of 2000 metaphase cells stained with Giemsa and centromere-FISH for dicentric chromosome assay (DCA) in cases of low-dose radiation exposure. In the present study, we analyzed the frequency of chromosome translocations using stored Carnoy's-fixed lymphocyte specimens from the previous study; these specimens were from 12 patients who were subject to chromosome painting of Chromosomes 1, 2 and 4. Chromosomes 1, 2 and 4 were analyzed in ∼5000 cells, which is equivalent to the whole-genome analysis of almost 2000 cells. The frequency of chromosome translocation was higher than the number of DICs formed, both before and after CT scanning. The frequency of chromosome translocations tended to be higher, but not significantly higher, in patients with a treatment history compared with patients without such a history. However, in contrast to the results for DIC formation, the frequency of translocations detected before and after the CT scan did not differ significantly. Therefore, analysis of chromosome translocation may not be a suitable assay for detecting chromosome aberrations in cases of low-dose radiation exposure from a CT scan. A significant increase in the frequency of chromosome translocations was not likely to be detected due to the high baseline before the CT scan; the high and variable frequency of translocations was probably due to multiple confounding factors in adults. PMID:26874116

  15. Analysis of chromosome translocation frequency after a single CT scan in adults

    PubMed Central

    Abe, Yu; Miura, Tomisato; Yoshida, Mitsuaki A.; Ujiie, Risa; Kurosu, Yumiko; Kato, Nagisa; Katafuchi, Atsushi; Tsuyama, Naohiro; Kawamura, Fumihiko; Ohba, Takashi; Inamasu, Tomoko; Shishido, Fumio; Noji, Hideyoshi; Ogawa, Kazuei; Yokouchi, Hiroshi; Kanazawa, Kenya; Ishida, Takashi; Muto, Satoshi; Ohsugi, Jun; Suzuki, Hiroyuki; Ishikawa, Tetsuo; Kamiya, Kenji; Sakai, Akira

    2016-01-01

    We recently reported an increase in dicentric chromosome (DIC) formation after a single computed tomography (CT) scan (5.78–60.27 mSv: mean 24.24 mSv) and we recommended analysis of 2000 metaphase cells stained with Giemsa and centromere-FISH for dicentric chromosome assay (DCA) in cases of low-dose radiation exposure. In the present study, we analyzed the frequency of chromosome translocations using stored Carnoy's-fixed lymphocyte specimens from the previous study; these specimens were from 12 patients who were subject to chromosome painting of Chromosomes 1, 2 and 4. Chromosomes 1, 2 and 4 were analyzed in ∼5000 cells, which is equivalent to the whole-genome analysis of almost 2000 cells. The frequency of chromosome translocation was higher than the number of DICs formed, both before and after CT scanning. The frequency of chromosome translocations tended to be higher, but not significantly higher, in patients with a treatment history compared with patients without such a history. However, in contrast to the results for DIC formation, the frequency of translocations detected before and after the CT scan did not differ significantly. Therefore, analysis of chromosome translocation may not be a suitable assay for detecting chromosome aberrations in cases of low-dose radiation exposure from a CT scan. A significant increase in the frequency of chromosome translocations was not likely to be detected due to the high baseline before the CT scan; the high and variable frequency of translocations was probably due to multiple confounding factors in adults. PMID:26874116

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  17. Stereolithographic vascular replicas from CT scans: choosing treatment strategies, teaching, and research from live patient scan data.

    PubMed

    Knox, Kimberly; Kerber, Charles W; Singel, Soren A; Bailey, Michael J; Imbesi, Steven G

    2005-01-01

    Our goal was to develop a system that would allow us to recreate live patient arterial pathology by using an industrial technique known as stereolithography (or rapid prototyping). In industry, drawings rendered into dicom files can be exported to a computer programmed to drive various industrial tools. Those tools then make a 3D structure shown by the original drawings. We manipulated CT scan dicom files to drive a stereolithography machine and were able to make replicas of the vascular diseases of three patients. PMID:15956511

  18. 18F-Fluorodeoxyglucose Positron Emission Tomography/CT Scanning in Diagnosing Vascular Prosthetic Graft Infection

    PubMed Central

    Saleem, Ben R.; Pol, Robert A.; Slart, Riemer H. J. A.; Reijnen, Michel M. P. J.; Zeebregts, Clark J.

    2014-01-01

    Vascular prosthetic graft infection (VPGI) is a severe complication after vascular surgery. CT-scan is considered the diagnostic tool of choice in advanced VPGI. The incidence of a false-negative result using CT is relatively high, especially in the presence of low-grade infections. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) scanning has been suggested as an alternative for the diagnosis and assessment of infectious processes. Hybrid 18F-FDG PET/CT has established the role of 18F-FDG PET for the assessment of suspected VPGI, providing accurate anatomic localization of the site of infection. However, there are no clear guidelines for the interpretation of the uptake patterns of 18F-FDG as clinical tool for VPGI. Based on the available literature it is suggested that a linear, diffuse, and homogeneous uptake should not be regarded as an infection whereas focal or heterogeneous uptake with a projection over the vessel on CT is highly suggestive of infection. Nevertheless, 18F-FDG PET and 18F-FDG PET/CT can play an important role in the detection of VPGI and monitoring response to treatment. However an accurate uptake and pattern recognition is warranted and cut-off uptake values and patterns need to be standardized before considering the technique to be the new standard. PMID:25210712

  19. Automatic detection of axillary lymphadenopathy on CT scans of untreated chronic lymphocytic leukemia patients

    NASA Astrophysics Data System (ADS)

    Liu, Jiamin; Hua, Jeremy; Chellappa, Vivek; Petrick, Nicholas; Sahiner, Berkman; Farooqui, Mohammed; Marti, Gerald; Wiestner, Adrian; Summers, Ronald M.

    2012-03-01

    Patients with chronic lymphocytic leukemia (CLL) have an increased frequency of axillary lymphadenopathy. Pretreatment CT scans can be used to upstage patients at the time of presentation and post-treatment CT scans can reduce the number of complete responses. In the current clinical workflow, the detection and diagnosis of lymph nodes is usually performed manually by examining all slices of CT images, which can be time consuming and highly dependent on the observer's experience. A system for automatic lymph node detection and measurement is desired. We propose a computer aided detection (CAD) system for axillary lymph nodes on CT scans in CLL patients. The lung is first automatically segmented and the patient's body in lung region is extracted to set the search region for lymph nodes. Multi-scale Hessian based blob detection is then applied to detect potential lymph nodes within the search region. Next, the detected potential candidates are segmented by fast level set method. Finally, features are calculated from the segmented candidates and support vector machine (SVM) classification is utilized for false positive reduction. Two blobness features, Frangi's and Li's, are tested and their free-response receiver operating characteristic (FROC) curves are generated to assess system performance. We applied our detection system to 12 patients with 168 axillary lymph nodes measuring greater than 10 mm. All lymph nodes are manually labeled as ground truth. The system achieved sensitivities of 81% and 85% at 2 false positives per patient for Frangi's and Li's blobness, respectively.

  20. Comparison of demons deformable registration-based methods for texture analysis of serial thoracic CT scans

    NASA Astrophysics Data System (ADS)

    Cunliffe, Alexandra R.; Al-Hallaq, Hania A.; Fei, Xianhan M.; Tuohy, Rachel E.; Armato, Samuel G.

    2013-02-01

    To determine how 19 image texture features may be altered by three image registration methods, "normal" baseline and follow-up computed tomography (CT) scans from 27 patients were analyzed. Nineteen texture feature values were calculated in over 1,000 32x32-pixel regions of interest (ROIs) randomly placed in each baseline scan. All three methods used demons registration to map baseline scan ROIs to anatomically matched locations in the corresponding transformed follow-up scan. For the first method, the follow-up scan transformation was subsampled to achieve a voxel size identical to that of the baseline scan. For the second method, the follow-up scan was transformed through affine registration to achieve global alignment with the baseline scan. For the third method, the follow-up scan was directly deformed to the baseline scan using demons deformable registration. Feature values in matched ROIs were compared using Bland- Altman 95% limits of agreement. For each feature, the range spanned by the 95% limits was normalized to the mean feature value to obtain the normalized range of agreement, nRoA. Wilcoxon signed-rank tests were used to compare nRoA values across features for the three methods. Significance for individual tests was adjusted using the Bonferroni method. nRoA was significantly smaller for affine-registered scans than for the resampled scans (p=0.003), indicating lower feature value variability between baseline and follow-up scan ROIs using this method. For both of these methods, however, nRoA was significantly higher than when feature values were calculated directly on demons-deformed followup scans (p<0.001). Across features and methods, nRoA values remained below 26%.

  1. Computed Tomography (CT) Scanning Facilitates Early Identification of Neonatal Cystic Fibrosis Piglets

    PubMed Central

    Guillon, Antoine; Chevaleyre, Claire; Barc, Celine; Berri, Mustapha; Adriaensen, Hans; Lecompte, François; Villemagne, Thierry; Pezant, Jérémy; Delaunay, Rémi; Moënne-Loccoz, Joseph; Berthon, Patricia; Bähr, Andrea; Wolf, Eckhard; Klymiuk, Nikolai; Attucci, Sylvie; Ramphal, Reuben; Sarradin, Pierre; Buzoni-Gatel, Dominique; Si-Tahar, Mustapha; Caballero, Ignacio

    2015-01-01

    Background Cystic Fibrosis (CF) is the most prevalent autosomal recessive disease in the Caucasian population. A cystic fibrosis transmembrane conductance regulator knockout (CFTR-/-) pig that displays most of the features of the human CF disease has been recently developed. However, CFTR-/- pigs presents a 100% prevalence of meconium ileus that leads to death in the first hours after birth, requiring a rapid diagnosis and surgical intervention to relieve intestinal obstruction. Identification of CFTR-/- piglets is usually performed by PCR genotyping, a procedure that lasts between 4 to 6 h. Here, we aimed to develop a procedure for rapid identification of CFTR-/- piglets that will allow placing them under intensive care soon after birth and immediately proceeding with the surgical correction. Methods and Principal Findings Male and female CFTR+/- pigs were crossed and the progeny was examined by computed tomography (CT) scan to detect the presence of meconium ileus and facilitate a rapid post-natal surgical intervention. Genotype was confirmed by PCR. CT scan presented a 94.4% sensitivity to diagnose CFTR-/- piglets. Diagnosis by CT scan reduced the birth-to-surgery time from a minimum of 10 h down to a minimum of 2.5 h and increased the survival of CFTR-/- piglets to a maximum of 13 days post-surgery as opposed to just 66 h after later surgery. Conclusion CT scan imaging of meconium ileus is an accurate method for rapid identification of CFTR-/- piglets. Early CT detection of meconium ileus may help to extend the lifespan of CFTR-/- piglets and, thus, improve experimental research on CF, still an incurable disease. PMID:26600426

  2. Raman and CT scan mapping of chalcogenide glass diffusion generated gradient index profiles

    NASA Astrophysics Data System (ADS)

    Lindberg, G. P.; Berg, R. H.; Deegan, J.; Benson, R.; Salvaggio, P. S.; Gross, N.; Weinstein, B. A.; Gibson, D.; Bayya, S.; Sanghera, J.; Nguyen, V.; Kotov, M.

    2016-05-01

    Metrology of a gradient index (GRIN) material is non-trivial, especially in the realm of infrared and large refractive index. Traditional methods rely on index matching fluids which are not available for indexes as high as those found in the chalcogenide glasses (2.4-3.2). By diffusing chalcogenide glasses of similar composition one can blend the properties in a continuous way. In an effort to measure this we will present data from both x-ray computed tomography scans (CT scans) and Raman mapping scans of the diffusion profiles. Proof of concept measurements on undiffused bonded sheets of chalcogenide glasses were presented previously. The profiles measured will be of axially stacked sheets of chalcogenide glasses diffused to create a linear GRIN profile and nested tubes of chalcogenide glasses diffused to create a radial parabolic GRIN profile. We will show that the x-ray absorption in the CT scan and the intensity of select Raman peaks spatially measured through the material are indicators of the concentration of the diffusion ions and correlate to the spatial change in refractive index. We will also present finite element modeling (FEM) results and compare them to post precision glass molded (PGM) elements that have undergone CT and Raman mapping.

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

    PubMed

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

    2014-04-01

    Computed tomography (CT) scans are indispensable in modern medicine; however, the spectacular rise in global use coupled with relatively high doses of ionizing radiation per examination have raised radiation protection concerns. Children are of particular concern because they are more sensitive to radiation-induced cancer compared with adults and have a long lifespan to express harmful effects which may offset clinical benefits of performing a scan. This paper describes the design and methodology of a nationwide study, the Dutch Pediatric CT Study, regarding risk of leukemia and brain tumors in children after radiation exposure from CT scans. It is a retrospective record-linkage cohort study with an expected number of 100,000 children who received at least one electronically archived CT scan covering the calendar period since the introduction of digital archiving until 2012. Information on all archived CT scans of these children will be obtained, including date of examination, scanned body part and radiologist's report, as well as the machine settings required for organ dose estimation. We will obtain cancer incidence by record linkage with external databases. In this article, we describe several approaches to the collection of data on archived CT scans, the estimation of radiation doses and the assessment of confounding. The proposed approaches provide useful strategies for data collection and confounder assessment for general retrospective record-linkage studies, particular those using hospital databases on radiological procedures for the assessment of exposure to ionizing or non-ionizing radiation. PMID:24748424

  4. Ultra-Low Dose Lung CT Perfusion Regularized by a Previous Scan

    PubMed Central

    Yu, Hengyong; Zhao, Shiying; Hoffman, Eric A.; Wang, Ge

    2009-01-01

    Rationale and Objectives Our previous scan regularized reconstruction (PSRR) method is proposed to reduce radiation dose and applied for lung perfusion studies. The normal and ultra-low dose lung CT perfusion studies are compared in terms of estimation accuracy of pulmonary functional parameters. Materials and Methods A sequences of sheep lung scans were performed in three prone, anesthetized sheep at normal and ultra-low doses. A scan protocol was developed for the ultra-low dose studies with ECG gating - time point one for a normal x-ray dose scan (100kV/150mAs) and time points 2–21 for low dose scans (80kV/17mAs). A nonlinear diffusion-based post-filtering (NDPF) method was applied to the difference images between the low-dose images and the high-quality reference image. The final images at 20 time points were generated by fusing the reference image with the filtered difference images. Results The power spectra of perfusion images and coherences with the normal scans show a great improvement in image quality of the ultra-low dose scans with PSRR relative to that without RSRR. The Gamma variate-fitting and the repeatability of the measurements of the mean transit time demonstrate that the key parameters of lung functions can be reliably accessed using PSRR. The variability of the ultra-low dose scan results obtained using PSRR is not substantially different from that between two normal dose scans. Conclusions Our studies have shown that a ~90% reduction in radiation dose is achievable using PSRR without compromising the quantitative CT measurements of regional lung functions. PMID:19201366

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

    SciTech Connect

    Wang, T; Zhu, L

    2014-06-15

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

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

    SciTech Connect

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

    2008-09-15

    Purpose: lower lobe lung tumors move with amplitudes of up to 2 cm due to respiration. To reduce respiration imaging artifacts in planning CT scans, 4D imaging techniques are used. Currently, we use a single (midventilation) frame of the 4D data set for clinical delineation of structures and radiotherapy planning. A single frame, however, often contains artifacts due to breathing irregularities, and is noisier than a conventional CT scan since the exposure per frame is lower. Moreover, the tumor may be displaced from the mean tumor position due to hysteresis. The aim of this work is to develop a framework for the acquisition of a good quality scan representing all scanned anatomy in the mean position by averaging transformed (deformed) CT frames, i.e., canceling out motion. A nonrigid registration method is necessary since motion varies over the lung. Methods and Materials: 4D and inspiration breath-hold (BH) CT scans were acquired for 13 patients. An iterative multiscale motion estimation technique was applied to the 4D CT scan, similar to optical flow but using image phase (gray-value transitions from bright to dark and vice versa) instead. From the (4D) deformation vector field (DVF) derived, the local mean position in the respiratory cycle was computed and the 4D DVF was modified to deform all structures of the original 4D CT scan to this mean position. A 3D midposition (MidP) CT scan was then obtained by (arithmetic or median) averaging of the deformed 4D CT scan. Image registration accuracy, tumor shape deviation with respect to the BH CT scan, and noise were determined to evaluate the image fidelity of the MidP CT scan and the performance of the technique. Results: Accuracy of the used deformable image registration method was comparable to established automated locally rigid registration and to manual landmark registration (average difference to both methods <0.5 mm for all directions) for the tumor region. From visual assessment, the registration was good

  7. Evolving Bioprosthetic Tissue Calcification Can Be Quantified Using Serial Multislice CT Scanning

    PubMed Central

    Meuris, B.; De Praetere, H.; Coudyzer, W.; Flameng, W.

    2013-01-01

    Background. We investigated the value of serial multislice CT scanning for in vivo determination of evolving tissue calcification in three separate experimental settings. Materials and Methods. Bioprosthetic valve tissue was implanted in three different conditions: (1) glutaraldehyde-fixed porcine stentless conduits in pulmonary position (n = 6); (2) glutaraldehyde-fixed stented pericardial valves in mitral position (n = 3); and (3) glutaraldehyde-fixed pericardial tissue as patch in the jugular vein and carotid artery (n = 16). Multislice CT scanning was performed at various time intervals. Results. In stentless conduits, the distribution of wall calcification can be reliably quantified with CT. After 20 weeks, the CT-determined mean calcium volume was 1831 ± 581 mm³, with a mean wall calcium content of 89.8 ± 44.4 μg/mg (r2 = 0.68). In stented pericardial valves implanted in mitral position, reliable determination of tissue mineralization is disturbed by scattering caused by the (continuously moving) alloy of the stent material. Pericardial patches in the neck vessels revealed progressive mineralization, with a significant increase in mean HU and calcium volume at 8 weeks after implantation, rising up to a level of 131.1 ± 39.6 mm³ (mean calcium volume score) and a mean calcium content of 19.1 ± 12.3 μg/mg. Conclusion. The process of bioprosthetic tissue mineralization can be visualized and quantified in vivo using multislice CT scanning. This allows determination of the kinetics of tissue mineralization with intermediate in vivo evaluations. PMID:24089616

  8. A computational framework for cancer response assessment based on oncological PET-CT scans.

    PubMed

    Sampedro, Frederic; Escalera, Sergio; Domenech, Anna; Carrio, Ignasi

    2014-12-01

    In this work we present a comprehensive computational framework to help in the clinical assessment of cancer response from a pair of time consecutive oncological PET-CT scans. In this scenario, the design and implementation of a supervised machine learning system to predict and quantify cancer progression or response conditions by introducing a novel feature set that models the underlying clinical context is described. Performance results in 100 clinical cases (corresponding to 200 whole body PET-CT scans) in comparing expert-based visual analysis and classifier decision making show up to 70% accuracy within a completely automatic pipeline and 90% accuracy when providing the system with expert-guided PET tumor segmentation masks. PMID:25450224

  9. Intracranial myeloid metaplasia: diagnosis by CT and Fe52 scans and treatment by cranial irradiation

    SciTech Connect

    Cornfield, D.B.; Shipkin, P.; Alavi, A.; Becker, J.; Peyster, R.

    1983-11-01

    A patient with longstanding agnogenic myeloid metaplasia developed a progressive dementia. CT scanning demonstrated multiple intracranial masses, and a Fe/sub 52/ bone marrow scan demonstrated erythroid activity within the masses and confirmed the suspicion of extra-medullary hematopoiesis. A potentially hazardous biopsy was avoided, and a course of cranial irradiation was administered, resulting in regression of the masses and clearing of the patient's dementia. Fe/sub 52/ scintigraphy provides a specific and useful diagnostic approach which may eliminate the need for invasive procedures.

  10. Childhood CT scans and cancer risk: impact of predisposing factors for cancer on the risk estimates.

    PubMed

    Journy, N; Roué, T; Cardis, E; Le Pointe, H Ducou; Brisse, H; Chateil, J-F; Laurier, D; Bernier, M-O

    2016-03-01

    To investigate the role of cancer predisposing factors (PFs) on the associations between paediatric computed tomography (CT) scan exposures and subsequent risk of central nervous system (CNS) tumours and leukaemia. A cohort of children who underwent a CT scan in 2000-2010 in 23 French radiology departments was linked with the national childhood cancers registry and national vital status registry; information on PFs was retrieved through hospital discharge databases. In children without PF, hazard ratios of 1.07 (95% CI 0.99-1.10) for CNS tumours (15 cases) and 1.16 (95% CI 0.77-1.27) for leukaemia (12 cases) were estimated for each 10 mGy increment in CT x-rays organ doses. These estimates were similar to those obtained in the whole cohort. In children with PFs, no positive dose-risk association was observed, possibly related to earlier non-cancer mortality in this group. Our results suggest a modifying effect of PFs on CT-related cancer risks, but need to be confirmed by longer follow-up and other studies. PMID:26878249

  11. Classification of pulmonary emphysema from chest CT scans using integral geometry descriptors

    NASA Astrophysics Data System (ADS)

    van Rikxoort, E. M.; Goldin, J. G.; Galperin-Aizenberg, M.; Brown, M. S.

    2011-03-01

    To gain insight into the underlying pathways of emphysema and monitor the effect of treatment, methods to quantify and phenotype the different types of emphysema from chest CT scans are of crucial importance. Current standard measures rely on density thresholds for individual voxels, which is influenced by inspiration level and does not take into account the spatial relationship between voxels. Measures based on texture analysis do take the interrelation between voxels into account and therefore might be useful for distinguishing different types of emphysema. In this study, we propose to use Minkowski functionals combined with rotation invariant Gaussian features to distinguish between healthy and emphysematous tissue and classify three different types of emphysema. Minkowski functionals characterize binary images in terms of geometry and topology. In 3D, four Minkowski functionals are defined. By varying the threshold and size of neighborhood around a voxel, a set of Minkowski functionals can be defined for each voxel. Ten chest CT scans with 1810 annotated regions were used to train the method. A set of 108 features was calculated for each training sample from which 10 features were selected to be most informative. A linear discriminant classifier was trained to classify each voxel in the lungs into a subtype of emphysema or normal lung. The method was applied to an independent test set of 30 chest CT scans with varying amounts and types of emphysema with 4347 annotated regions of interest. The method is shown to perform well, with an overall accuracy of 95%.

  12. [A case of bronchiolitis obliterans organizing pneumonia: diagnostic utility of bronchoalveolar lavage and CT scan].

    PubMed

    Hyakudo, T; Yoshii, C; Nikaido, Y; Yokosaki, Y; Nagata, N; Nakata, H; Kido, M

    1994-08-01

    A 54-year-old female was admitted to our hospital because of abnormal shadows on chest X-ray at annual checkup. She complained of dyspnea on exertion. Chest X-ray findings showed an increase in density at the bilateral lower lung fields and unclearness of the silhouette of the heart and the diaphragm. CT scan findings revealed irregular opacities of various density with many small cystic changes and air bronchograms and air bronchiolograms. The pulmonary function test showed restrictive ventilatory disturbance and reduced diffusing capacity. BALF findings revealed an increase in the total cell count, an increase in the percentage of lymphocytes and a decrease in the OKT4+/OKT8+ ratio. TBLB specimen showed infiltration of mononuclear cells in alveolar septa and organizing exudate in alveolar ducts. These findings suggested a diagnosis of BOOP rather than IPF, and an open lung biopsy was performed. Open lung biopsy specimen showed obstructive bronchiolitis with polypoid granulation tissue and thickening of alveolar septa with infiltration of mononuclear cells, and she was diagnosed as having BOOP. She responded well to corticosteroid and is free from any abnormalities on chest X-ray, CT scan and pulmonary function test at present. Analysis of BALF and CT scan findings are useful for the differential diagnosis of BOOP and IPF. PMID:7807756

  13. Carotid plaque characterization using CT and MRI scans for synergistic image analysis

    NASA Astrophysics Data System (ADS)

    Getzin, Matthew; Xu, Yiqin; Rao, Arhant; Madi, Saaussan; Bahadur, Ali; Lennartz, Michelle R.; Wang, Ge

    2014-09-01

    Noninvasive determination of plaque vulnerability has been a holy grail of medical imaging. Despite advances in tomographic technologies , there is currently no effective way to identify vulnerable atherosclerotic plaques with high sensitivity and specificity. Computed tomography (CT) and magnetic resonance imaging (MRI) are widely used, but neither provides sufficient information of plaque properties. Thus, we are motivated to combine CT and MRI imaging to determine if the composite information can better reflect the histological determination of plaque vulnerability. Two human endarterectomy specimens (1 symptomatic carotid and 1 stable femoral) were imaged using Scanco Medical Viva CT40 and Bruker Pharmascan 16cm 7T Horizontal MRI / MRS systems. μCT scans were done at 55 kVp and tube current of 70 mA. Samples underwent RARE-VTR and MSME pulse sequences to measure T1, T2 values, and proton density. The specimens were processed for histology and scored for vulnerability using the American Heart Association criteria. Single modality-based analyses were performed through segmentation of key imaging biomarkers (i.e. calcification and lumen), image registration, measurement of fibrous capsule, and multi-component T1 and T2 decay modeling. Feature differences were analyzed between the unstable and stable controls, symptomatic carotid and femoral plaque, respectively. By building on the techniques used in this study, synergistic CT+MRI analysis may provide a promising solution for plaque characterization in vivo.

  14. Refractory Epilepsy-MRI, EEG and CT scan, a Correlative Clinical Study

    PubMed Central

    Nikodijevic, Dijana; Baneva–Dolnenec, Natalija; Petrovska-Cvetkovska, Dragana; Caparoska, Daniela

    2016-01-01

    OBJECTIVES: Refractory epilepsies (RE), as well as, the surgically correctable syndromes, are of great interest, since they affect the very young population of children and adolescents. The early diagnosis and treatment are very important in preventing the psychosocial disability. Therefore MRI and EEG are highly sensitive methods in the diagnosis and localization of epileptogenic focus, but also in pre-surgical evaluation of these patients. The aim of our study is to correlate the imaging findings of EEG, MRI and CT scan in refractory symptomatic epilepsies, and to determine their specificity in detecting the epileptogenic focus. METHODS: The study was prospective with duration of over two years, open-labelled, and involved a group of 37 patients that had been evaluated and diagnosed as refractory epilepsy patients. In the evaluation the type and frequency of seizures were considered, together with the etiologic factors and their association, and finally the risk for developing refractory epilepsy was weighted. EEG and MRI findings and CT scan results were evaluated for their specificity and sensitivity in detecting the epileptogenic focus, and the correlation between them was analyzed. RESULTS: Regarding the type of seizures considered in our study, the patients with PCS (partial complex seizures) dominated, as opposed to those with generalized seizures (GS) (D=1.178, p < 0.05). Positive MRI findings were registered in 28 patients (75.7%). Most of them were patients with hippocampal sclerosis, 12 (42.8%), and also they were found to have the highest risk of developing refractory epilepsy (RE) (Odds ratio = 5.7), and the highest association between the etiologic factor and refractory epilepsy (p < 0.01). In detecting the epileptogenic focus, a significant difference was found (p < 0.01) between MRI and CT scan findings, especially in patients with hippocampal sclerosis and cerebral malformations. There was a strong correlation between the MRI findings and the

  15. Potential for Adult-Based Epidemiological Studies to Characterize Overall Cancer Risks Associated with a Lifetime of CT Scans

    PubMed Central

    Shuryak, Igor; Lubin, Jay H.; Brenner, David J.

    2014-01-01

    Recent epidemiological studies have suggested that radiation exposure from pediatric CT scanning is associated with small excess cancer risks. However, the majority of CT scans are performed on adults, and most radiation-induced cancers appear during middle or old age, in the same age range as background cancers. Consequently, a logical next step is to investigate the effects of CT scanning in adulthood on lifetime cancer risks by conducting adult-based, appropriately designed epidemiological studies. Here we estimate the sample size required for such studies to detect CT-associated risks. This was achieved by incorporating different age-, sex-, time- and cancer type-dependent models of radiation carcinogenesis into an in silico simulation of a population-based cohort study. This approach simulated individual histories of chest and abdominal CT exposures, deaths and cancer diagnoses. The resultant sample sizes suggest that epidemiological studies of realistically sized cohorts can detect excess lifetime cancer risks from adult CT exposures. For example, retrospective analysis of CT exposure and cancer incidence data from a population-based cohort of 0.4 to 1.3 million (depending on the carcinogenic model) CT-exposed UK adults, aged 25–65 in 1980 and followed until 2015, provides 80% power for detecting cancer risks from chest and abdominal CT scans. PMID:24828111

  16. Hierarchical pictorial structures for simultaneously localizing multiple organs in volumetric pre-scan CT

    NASA Astrophysics Data System (ADS)

    Montillo, Albert; Song, Qi; Das, Bipul; Yin, Zhye

    2015-03-01

    Parsing volumetric computed tomography (CT) into 10 or more salient organs simultaneously is a challenging task with many applications such as personalized scan planning and dose reporting. In the clinic, pre-scan data can come in the form of very low dose volumes acquired just prior to the primary scan or from an existing primary scan. To localize organs in such diverse data, we propose a new learning based framework that we call hierarchical pictorial structures (HPS) which builds multiple levels of models in a tree-like hierarchy that mirrors the natural decomposition of human anatomy from gross structures to finer structures. Each node of our hierarchical model learns (1) the local appearance and shape of structures, and (2) a generative global model that learns probabilistic, structural arrangement. Our main contribution is twofold. First we embed the pictorial structures approach in a hierarchical framework which reduces test time image interpretation and allows for the incorporation of additional geometric constraints that robustly guide model fitting in the presence of noise. Second we guide our HPS framework with the probabilistic cost maps extracted using random decision forests using volumetric 3D HOG features which makes our model fast to train and fast to apply to novel test data and posses a high degree of invariance to shape distortion and imaging artifacts. All steps require approximate 3 mins to compute and all organs are located with suitably high accuracy for our clinical applications such as personalized scan planning for radiation dose reduction. We assess our method using a database of volumetric CT scans from 81 subjects with widely varying age and pathology and with simulated ultra-low dose cadaver pre-scan data.

  17. National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan

    PubMed Central

    Lin, Chung-Jung; Mok, Greta S. P.; Tsai, Mang-Fen; Tsai, Wei-Ta; Yang, Bang-Hung; Tu, Chun-Yuan; Wu, Tung-Hsin

    2015-01-01

    Introduction The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database. Materials and Methods Taiwan’s Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed. Results CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C. Conclusion CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices. PMID:26125549

  18. A new CT collimator for producing two simultaneous overlapping slices from one scan. [for biomedical applications

    NASA Technical Reports Server (NTRS)

    Kwoh, Y. S.; Glenn, W. V., Jr.; Reed, I. S.; Truong, T. K.

    1981-01-01

    A new CT collimator is developed which is capable of producing two simultaneous successive overlapping images from a single scan. The collimator represents a modification of the standard EMI 5005 collimator achieved by alternately masking one end or portions of both ends of the X-ray detectors at a 13-mm beamwidth so that a set of 540 filtered projections is obtained for each scan which can be separated into two sets of interleaved projections corresponding to views 3 mm apart. Tests have demonstrated that the quality of the images produced from these two projections almost equals the quality of those produced by the standard collimator from two separate scans. The new collimator may thus be used to achieve a speed improvement in the generation of overlapping sections as well as a reduction in X-ray dosage.

  19. CT Scan Does Not Differentiate Patients with Hepatopulmonary Syndrome from Other Patients with Liver Disease

    PubMed Central

    Prabhudesai, Vikramaditya; Castel, Helene; Gupta, Samir

    2016-01-01

    Background Hepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vascular dilatations, and impaired oxygenation. The gold standard for detection of intrapulmonary vascular dilatations in HPS is contrast echocardiography. However, two small studies have suggested that patients with HPS have larger segmental pulmonary arterial diameters than both normal subjects and normoxemic subjects with cirrhosis, when measured by CT. We sought to compare CT imaging-based pulmonary vasodilatation in patients with HPS, patients with liver dysfunction without HPS, and matching controls on CT imaging. Methods We performed a retrospective cohort study at two quaternary care Canadian HPS centers. We analyzed CT thorax scans in 23 patients with HPS, 29 patients with liver dysfunction without HPS, and 52 gender- and age-matched controls. We measured the artery-bronchus ratios (ABRs) in upper and lower lung zones, calculated the “delta ABR” by subtracting the upper from the lower ABR, compared these measurements between groups, and correlated them with clinically relevant parameters (partial pressure of arterial oxygen, alveolar-arterial oxygen gradient, macroaggregated albumin shunt fraction, and diffusion capacity). We repeated measurements in patients with post-transplant CTs. Results Patients had significantly larger lower zone ABRs and delta ABRs than controls (1.20 +/- 0.19 versus 0.98 +/- 0.10, p<0.01; and 0.12 +/- 0.17 versus -0.06 +/- 0.10, p<0.01, respectively). However, there were no significant differences between liver disease patients with and without HPS, nor any significant correlations between CT measurements and clinically relevant parameters. There were no significant changes in ABRs after liver transplantation (14 patients). Conclusions Basilar segmental artery-bronchus ratios are larger in patients with liver disease than in normal controls, but this vasodilatation is no more severe in patients with HPS. CT does not distinguish patients

  20. The impact of CT scan energy on range calculation in proton therapy planning.

    PubMed

    Grantham, Kevin K; Li, Hua; Zhao, Tianyu; Klein, Eric E

    2015-01-01

    The purpose of this study was to investigate the impact of tube potential (kVp) on the CT number (HU) to proton stopping power ratio (PSPR) conversion. The range and dosimetric change introduced by a mismatch in kVp used for the CT scan and the HU to PSPR table, based on a specific kVp, used to calculate dose are analyzed. Three HU to PSPR curves, corresponding to three kVp settings on the CT scanner, were created. A treatment plan was created for a single beam in a water phantom passing through a wedge-shaped bone heterogeneity. The dose was recalculated by changing only the HU to PSPR table used in the dose calculation. The change in the position of the distal 90% isodose line was recorded as a function of heterogeneity thickness along the beam path. The dosimetric impact of a mismatch in kVp between the CT and the HU to PSPR table was investigated by repeating this procedure for five clinical plans comparing DVH data and dose difference distributions. The HU to PSPR tables diverge for CT numbers greater than 200 HU. In the phantom plan, the divergence of the tables resulted in a difference in range of 1.6 mm per cm of bone in the beam path, for the HU used. For the clinical plans, the dosimetric effect of a kVp mismatch depends on the amount of bone in the beam path and the proximity of OARs to the distal range of the planned beams. A mismatch in kVp between the CT and the HU to PSPR table can introduce inaccuracy in the proton beam range. For dense bone, the measured range difference was approximately 1.6 mm per cm of bone along the beam path. However, the clinical cases analyzed showed a range change of 1 mm or less. Caution is merited when such a mismatch may occur. PMID:26699561

  1. Analysis of calibration materials to improve dual-energy CT scanning for petrophysical applications

    SciTech Connect

    Ayyalasomavaiula, K.; McIntyre, D.; Jain, J.; Singh, J.; Yueh, F.

    2011-01-01

    Dual energy CT-scanning is a rapidly emerging imaging technique employed in non-destructive evaluation of various materials. Although CT (Computerized Tomography) has been used for characterizing rocks and visualizing and quantifying multiphase flow through rocks for over 25 years, most of the scanning is done at a voltage setting above 100 kV for taking advantage of the Compton scattering (CS) effect, which responds to density changes. Below 100 kV the photoelectric effect (PE) is dominant which responds to the effective atomic numbers (Zeff), which is directly related to the photo electric factor. Using the combination of the two effects helps in better characterization of reservoir rocks. The most common technique for dual energy CT-scanning relies on homogeneous calibration standards to produce the most accurate decoupled data. However, the use of calibration standards with impurities increases the probability of error in the reconstructed data and results in poor rock characterization. This work combines ICP-OES (inductively coupled plasma optical emission spectroscopy) and LIBS (laser induced breakdown spectroscopy) analytical techniques to quantify the type and level of impurities in a set of commercially purchased calibration standards used in dual-energy scanning. The Zeff data on the calibration standards with and without impurity data were calculated using the weighted linear combination of the various elements present and used in calculating Zeff using the dual energy technique. Results show 2 to 5% difference in predicted Zeff values which may affect the corresponding log calibrations. The effect that these techniques have on improving material identification data is discussed and analyzed. The workflow developed in this paper will translate to a more accurate material identification estimates for unknown samples and improve calibration of well logging tools.

  2. Automatic classication of pulmonary function in COPD patients using trachea analysis in chest CT scans

    NASA Astrophysics Data System (ADS)

    van Rikxoort, E. M.; de Jong, P. A.; Mets, O. M.; van Ginneken, B.

    2012-03-01

    Chronic Obstructive Pulmonary Disease (COPD) is a chronic lung disease that is characterized by airflow limitation. COPD is clinically diagnosed and monitored using pulmonary function testing (PFT), which measures global inspiration and expiration capabilities of patients and is time-consuming and labor-intensive. It is becoming standard practice to obtain paired inspiration-expiration CT scans of COPD patients. Predicting the PFT results from the CT scans would alleviate the need for PFT testing. It is hypothesized that the change of the trachea during breathing might be an indicator of tracheomalacia in COPD patients and correlate with COPD severity. In this paper, we propose to automatically measure morphological changes in the trachea from paired inspiration and expiration CT scans and investigate the influence on COPD GOLD stage classification. The trachea is automatically segmented and the trachea shape is encoded using the lengths of rays cast from the center of gravity of the trachea. These features are used in a classifier, combined with emphysema scoring, to attempt to classify subjects into their COPD stage. A database of 187 subjects, well distributed over the COPD GOLD stages 0 through 4 was used for this study. The data was randomly divided into training and test set. Using the training scans, a nearest mean classifier was trained to classify the subjects into their correct GOLD stage using either emphysema score, tracheal shape features, or a combination. Combining the proposed trachea shape features with emphysema score, the classification performance into GOLD stages improved with 11% to 51%. In addition, an 80% accuracy was achieved in distinguishing healthy subjects from COPD patients.

  3. In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans

    PubMed Central

    Zhang, Da; Padole, Atul; Li, Xinhua; Singh, Sarabjeet; Khawaja, Ranish Deedar Ali; Lira, Diego; Liu, Tianyu; Shi, Jim Q.; Otrakji, Alexi; Kalra, Mannudeep K.; Xu, X. George; Liu, Bob

    2014-01-01

    Purpose: To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Methods: Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin doses were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. Results: The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8% − 25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2 ± 3.3 and 16.5 ± 2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling the

  4. In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans

    SciTech Connect

    Zhang, Da; Padole, Atul; Li, Xinhua; Singh, Sarabjeet; Khawaja, Ranish Deedar Ali; Lira, Diego; Shi, Jim Q.; Otrakji, Alexi; Kalra, Mannudeep K.; Liu, Bob; Liu, Tianyu; Xu, X. George

    2014-09-15

    Purpose: To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Methods: Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin doses were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. Results: The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8% − 25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2 ± 3.3 and 16.5 ± 2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling the

  5. Regarding the Credibility of Data Showing an Alleged Association of Cancer with Radiation from CT Scans.

    PubMed

    Socol, Yehoshua; Welsh, James S

    2016-02-01

    Computed tomography (CT) scans are of high clinical value as a diagnostic technique, and new applications continue to be identified. However, their application is challenged by emerging concerns regarding carcinogenesis from their radiation. Recent articles made a significant contribution to the above-mentioned concerns by reporting evidence for direct association of the radiation from CT scans with cancer. Such interpretation of the data has already been criticized; there is the possibility of reverse causation due to confounding factors. Nevertheless, such work has had a high impact, with one article being cited more than 300 times from the Web of Science Core Collection within 2 years. However, the data points on cancer relative risk versus CT dose in that article fit straight lines corresponding to the linear no-threshold hypothesis suspiciously well. Here, by applying rigorous statistical analysis, it is shown that the probability of the fit truly being that good or better is only 2%. The results of such studies therefore appear "too good to be true" and the credibility of their conclusions must be questioned. PMID:25616624

  6. Cervical CT scan-guided epidural blood patches for spontaneous intracranial hypotension.

    PubMed

    Maingard, Julian; Giles, Lauren; Marriott, Mark; Phal, Pramit M

    2015-12-01

    We describe two patients with spontaneous intracranial hypotension (SIH), presenting with postural headache due to C1-C2 cerebrospinal fluid (CSF) leak. Both patients were refractory to lumbar epidural blood patching (EBP), and subsequently underwent successful CT scan-guided cervical EBP. SIH affects approximately 1 in 50,000 patients, with females more frequently affected. Its associated features are variable, and as such, misdiagnosis is common. Therefore, imaging plays an important role in the diagnostic workup of SIH and can include MRI of the brain and spine, CT myelogram, and radionuclide cisternography. In patients with an established diagnosis and confirmed CSF leak, symptoms will usually resolve with conservative management. However, in a select subgroup of patients, the symptoms are refractory to medical management and require more invasive therapies. In patients with cervical leaks, EBP in the cervical region is an effective management approach, either in close proximity to, or directly targeting a dural defect. CT scan-guided cervical EBP is an effective treatment approach in refractory SIH, and should be considered in those patients who are refractory to conservative management. PMID:26209918

  7. TH-C-18A-11: Investigating the Minimum Scan Parameters Required to Generate Free-Breathing Fast-Helical CT Scans Without Motion-Artifacts

    SciTech Connect

    Thomas, D; Neylon, J; Dou, T; Jani, S; Lamb, J; Low, D; Tan, J

    2014-06-15

    Purpose: A recently proposed 4D-CT protocol uses deformable registration of free-breathing fast-helical CT scans to generate a breathing motion model. In order to allow accurate registration, free-breathing images are required to be free of doubling-artifacts, which arise when tissue motion is greater than scan speed. This work identifies the minimum scanner parameters required to successfully generate free-breathing fast-helical scans without doubling-artifacts. Methods: 10 patients were imaged under free breathing conditions 25 times in alternating directions with a 64-slice CT scanner using a low dose fast helical protocol. A high temporal resolution (0.1s) 4D-CT was generated using a patient specific motion model and patient breathing waveforms, and used as the input for a scanner simulation. Forward projections were calculated using helical cone-beam geometry (800 projections per rotation) and a GPU accelerated reconstruction algorithm was implemented. Various CT scanner detector widths and rotation times were simulated, and verified using a motion phantom. Doubling-artifacts were quantified in patient images using structural similarity maps to determine the similarity between axial slices. Results: Increasing amounts of doubling-artifacts were observed with increasing rotation times > 0.2s for 16×1mm slice scan geometry. No significant increase in doubling artifacts was observed for 64×1mm slice scan geometry up to 1.0s rotation time although blurring artifacts were observed >0.6s. Using a 16×1mm slice scan geometry, a rotation time of less than 0.3s (53mm/s scan speed) would be required to produce images of similar quality to a 64×1mm slice scan geometry. Conclusion: The current generation of 16 slice CT scanners, which are present in most Radiation Oncology departments, are not capable of generating free-breathing sorting-artifact-free images in the majority of patients. The next generation of CT scanners should be capable of at least 53mm/s scan speed

  8. CT scan diagnosis of hepatic adenoma in a case of von Gierke disease

    PubMed Central

    Daga, Bipin Valchandji; Shah, Vaibhav R; More, Rahul B

    2012-01-01

    Hepatic adenoma is a well-defined, benign, solitary tumor of the liver. In individuals with glycogen storage disease I, adenoma tends to occur at a relatively younger age and can be multiple (adenomatosis). Imaging plays a pivotal role in diagnosing hepatic adenoma and in differentiating adenoma from other focal hepatic lesions. Especially in patients with von Gierke disease, in addition to the associated hepatomegaly caused by steatohepatitis and the diffusely reduced attenuation of the liver parenchyma seen on CT, there may be more than one hepatic adenoma in up to 40% of patients. Malignant degeneration of hepatic adenoma into hepatocellular carcinoma can occur and hence imaging is important for prompt diagnosis of adenoma and its complications. In this case report, we present a case of liver adenoma diagnosed by CT scan in a patient with von Gierke disease. PMID:22623817

  9. Cerebral blood flow and brain atrophy correlated by xenon contrast CT scanning

    SciTech Connect

    Kitagawa, Y.; Meyer, J.S.; Tanahashi, N.; Rogers, R.L.; Tachibana, H.; Kandula, P.; Dowell, R.E.; Mortel, K.F.

    1985-11-01

    Correlations between cerebral blood flow (CBF) measured during stable xenon contrast CT scanning and standard CT indices of brain atrophy were investigated in the patients with senile dementia of Alzheimer type, multi-infarct dementia and idiopathic Parkinson's disease. Compared to age-matched normal volunteers, significant correlations were found in patients with idiopathic Parkinson's disease between cortical and subcortical gray matter blood flow and brain atrophy estimated by the ventricular body ratio, and mild to moderate brain atrophy were correlated with stepwise CBF reductions. However, in patients with senile dementia of Alzheimer type and multi-infarct dementia, brain atrophy was not associated with stepwise CBF reductions. Overall correlations between brain atrophy and reduced CBF were weak. Mild degrees of brain atrophy are not always associated with reduced CBF.

  10. Initial experience with optical-CT scanning of RadBall Dosimeters.

    PubMed

    Oldham, M; Clift, C; Thomas, A; Farfan, E; Foley, T; Jannik, T; Adamovics, J; Holmes, C; Stanley, S

    2010-12-01

    The RadBall dosimeter is a novel device for providing 3-D information on the magnitude and distribution of contaminant sources of unknown radiation in a given hot cell, glovebox, or contaminated room. The device is presently under evaluation by the National Nuclear Lab (NNL, UK) and the Savannah River National Laboratory (SRNL, US), for application as a diagnostic device for such unknown contaminants in the nuclear industry. A critical component of the technique is imaging the dose distribution recorded in the RadBall using optical-CT scanning. Here we present our initial investigations using the Duke Mid-sized Optical-CT Scanner (DMOS) to image dose distributions deposited in RadBalls exposed to a variety of radiation treatments. PMID:21218190

  11. Initial experience with optical-CT scanning of RadBall Dosimeters

    PubMed Central

    Oldham, M; Clift, C; Thomas, A; Farfan, E; Foley, T; Jannik, T; Adamovics, J; Holmes, C; Stanley, S

    2010-01-01

    The RadBall dosimeter is a novel device for providing 3-D information on the magnitude and distribution of contaminant sources of unknown radiation in a given hot cell, glovebox, or contaminated room. The device is presently under evaluation by the National Nuclear Lab (NNL, UK) and the Savannah River National Laboratory (SRNL, US), for application as a diagnostic device for such unknown contaminants in the nuclear industry. A critical component of the technique is imaging the dose distribution recorded in the RadBall using optical-CT scanning. Here we present our initial investigations using the Duke Mid-sized Optical-CT Scanner (DMOS) to image dose distributions deposited in RadBalls exposed to a variety of radiation treatments. PMID:21218190

  12. Initial experience with optical-CT scanning of RadBall Dosimeters

    NASA Astrophysics Data System (ADS)

    Oldham, M.; Clift, C.; Thomas, A.; Farfan, E.; Foley, T.; Jannik, T.; Adamovics J.; Holmes, C.; Stanley, S.

    2010-11-01

    The RadBall dosimeter is a novel device for providing 3-D information on the magnitude and distribution of contaminant sources of unknown radiation in a given hot cell, glovebox, or contaminated room. The device is presently under evaluation by the National Nuclear Lab (NNL, UK) and the Savannah River National Laboratory (SRNL, US), for application as a diagnostic device for such unknown contaminants in the nuclear industry. A critical component of the technique is imaging the dose distribution recorded in the RadBall using optical-CT scanning. Here we present our initial investigations using the Duke Mid-sized Optical-CT Scanner (DMOS) to image dose distributions deposited in RadBalls exposed to a variety of radiation treatments.

  13. Construction and analysis of a head CT-scan database for craniofacial reconstruction.

    PubMed

    Tilotta, Françoise; Richard, Frédéric; Glaunès, Joan; Berar, Maxime; Gey, Servane; Verdeille, Stéphane; Rozenholc, Yves; Gaudy, J F

    2009-10-30

    This paper is devoted to the construction of a complete database which is intended to improve the implementation and the evaluation of automated facial reconstruction. This growing database is currently composed of 85 head CT-scans of healthy European subjects aged 20-65 years old. It also includes the triangulated surfaces of the face and the skull of each subject. These surfaces are extracted from CT-scans using an original combination of image-processing techniques which are presented in the paper. Besides, a set of 39 referenced anatomical skull landmarks were located manually on each scan. Using the geometrical information provided by triangulated surfaces, we compute facial soft-tissue depths at each known landmark positions. We report the average thickness values at each landmark and compare our measures to those of the traditional charts of [J. Rhine, C.E. Moore, Facial Tissue Thickness of American Caucasoïds, Maxwell Museum of Anthropology, Albuquerque, New Mexico, 1982] and of several recent in vivo studies [M.H. Manhein, G.A. Listi, R.E. Barsley, et al., In vivo facial tissue depth measurements for children and adults, Journal of Forensic Sciences 45 (1) (2000) 48-60; S. De Greef, P. Claes, D. Vandermeulen, et al., Large-scale in vivo Caucasian facial soft tissue thickness database for craniofacial reconstruction, Forensic Science International 159S (2006) S126-S146; R. Helmer, Schödelidentifizierung durch elektronische bildmischung, Kriminalistik Verlag GmbH, Heidelberg, 1984]. PMID:19665327

  14. Automatic segmentation of the facial nerve and chorda tympani in pediatric CT scans

    PubMed Central

    Reda, Fitsum A.; Noble, Jack H.; Rivas, Alejandro; McRackan, Theodore R.; Labadie, Robert F.; Dawant, Benoit M.

    2011-01-01

    Purpose: Cochlear implant surgery is used to implant an electrode array in the cochlea to treat hearing loss. The authors recently introduced a minimally invasive image-guided technique termed percutaneous cochlear implantation. This approach achieves access to the cochlea by drilling a single linear channel from the outer skull into the cochlea via the facial recess, a region bounded by the facial nerve and chorda tympani. To exploit existing methods for computing automatically safe drilling trajectories, the facial nerve and chorda tympani need to be segmented. The goal of this work is to automatically segment the facial nerve and chorda tympani in pediatric CT scans. Methods: The authors have proposed an automatic technique to achieve the segmentation task in adult patients that relies on statistical models of the structures. These models contain intensity and shape information along the central axes of both structures. In this work, the authors attempted to use the same method to segment the structures in pediatric scans. However, the authors learned that substantial differences exist between the anatomy of children and that of adults, which led to poor segmentation results when an adult model is used to segment a pediatric volume. Therefore, the authors built a new model for pediatric cases and used it to segment pediatric scans. Once this new model was built, the authors employed the same segmentation method used for adults with algorithm parameters that were optimized for pediatric anatomy. Results: A validation experiment was conducted on 10 CT scans in which manually segmented structures were compared to automatically segmented structures. The mean, standard deviation, median, and maximum segmentation errors were 0.23, 0.17, 0.18, and 1.27 mm, respectively. Conclusions: The results indicate that accurate segmentation of the facial nerve and chorda tympani in pediatric scans is achievable, thus suggesting that safe drilling trajectories can also be computed

  15. Optimal scan time for evaluation of parathyroid adenoma with [18F]-fluorocholine PET/CT

    PubMed Central

    Rep, Sebastijan; Lezaic, Luka; Kocjan, Tomaz; Pfeifer, Marija; Sever, Mojca Jensterle; Simoncic, Urban; Tomse, Petra; Hocevar, Marko

    2015-01-01

    Background Parathyroid adenomas, the most common cause of primary hyperparathyroidism, are benign tumours which autonomously produce and secrete parathyroid hormone. [18F]-fluorocholine (FCH), PET marker of cellular proliferation, was recently demonstrated to accumulate in lesions representing enlarged parathyroid tissue; however, the optimal time to perform FCH PET/CT after FCH administration is not known. The aim of this study was to determine the optimal scan time of FCH PET/CT in patients with primary hyperparathyroidism. Patients and methods. 43 patients with primary hyperparathyroidism were enrolled in this study. A triple-phase PET/CT imaging was performed five minutes, one and two hours after the administration of FCH. Regions of interest (ROI) were placed in lesions representing enlarged parathyroid tissue and thyroid tissue. Standardized uptake value (SUVmean), retention index and lesion contrast for parathyroid and thyroid tissue were calculated. Results Accumulation of FCH was higher in lesions representing enlarged parathyroid tissue in comparison to the thyroid tissue with significantly higher SUVmean in the second and in the third phase (p < 0.0001). Average retention index decreased significantly between the first and the second phase and increased significantly between the second and the third phase in lesions representing enlarged parathyroid tissue and decreased significantly over all three phases in thyroid tissue (p< 0.0001). The lesion contrast of lesions representing enlarged parathyroid tissue and thyroid tissue was significantly better in the second and the third phase compared to the first phase (p < 0.05). Conclusions According to the results the optimal scan time of FCH PET/CT for localization of lesions representing enlarged parathyroid tissue is one hour after administration of the FCH. PMID:26834518

  16. Semi-automated method to measure pneumonia severity in mice through computed tomography (CT) scan analysis

    NASA Astrophysics Data System (ADS)

    Johri, Ansh; Schimel, Daniel; Noguchi, Audrey; Hsu, Lewis L.

    2010-03-01

    Imaging is a crucial clinical tool for diagnosis and assessment of pneumonia, but quantitative methods are lacking. Micro-computed tomography (micro CT), designed for lab animals, provides opportunities for non-invasive radiographic endpoints for pneumonia studies. HYPOTHESIS: In vivo micro CT scans of mice with early bacterial pneumonia can be scored quantitatively by semiautomated imaging methods, with good reproducibility and correlation with bacterial dose inoculated, pneumonia survival outcome, and radiologists' scores. METHODS: Healthy mice had intratracheal inoculation of E. coli bacteria (n=24) or saline control (n=11). In vivo micro CT scans were performed 24 hours later with microCAT II (Siemens). Two independent radiologists scored the extent of airspace abnormality, on a scale of 0 (normal) to 24 (completely abnormal). Using the Amira 5.2 software (Mercury Computer Systems), a histogram distribution of voxel counts between the Hounsfield range of -510 to 0 was created and analyzed, and a segmentation procedure was devised. RESULTS: A t-test was performed to determine whether there was a significant difference in the mean voxel value of each mouse in the three experimental groups: Saline Survivors, Pneumonia Survivors, and Pneumonia Non-survivors. It was found that the voxel count method was able to statistically tell apart the Saline Survivors from the Pneumonia Survivors, the Saline Survivors from the Pneumonia Non-survivors, but not the Pneumonia Survivors vs. Pneumonia Non-survivors. The segmentation method, however, was successfully able to distinguish the two Pneumonia groups. CONCLUSION: We have pilot-tested an evaluation of early pneumonia in mice using micro CT and a semi-automated method for lung segmentation and scoring system. Statistical analysis indicates that the system is reliable and merits further evaluation.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  18. Clinical Utility of 4D FDG-PET/CT Scans in Radiation Treatment Planning

    SciTech Connect

    Aristophanous, Michalis; Sher, David J.; Allen, Aaron M.; Larson, Elysia; Chen, Aileen B.

    2012-01-01

    Purpose: The potential role of four-dimensional (4D) positron emission tomography (PET)/computed tomography (CT) in radiation treatment planning, relative to standard three-dimensional (3D) PET/CT, was examined. Methods and Materials: Ten patients with non-small-cell lung cancer had sequential 3D and 4D [{sup 18}F]fluorodeoxyglucose PET/CT scans in the treatment position prior to radiation therapy. The gross tumor volume and involved lymph nodes were contoured on the PET scan by use of three different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; a technique with a constant threshold of standardized uptake value (SUV) greater than 2.5; and an automatic segmentation technique. For each technique, the tumor volume was defined on the 3D scan (VOL3D) and on the 4D scan (VOL4D) by combining the volume defined on each of the five breathing phases individually. The range of tumor motion and the location of each lesion were also recorded, and their influence on the differences observed between VOL3D and VOL4D was investigated. Results: We identified and analyzed 22 distinct lesions, including 9 primary tumors and 13 mediastinal lymph nodes. Mean VOL4D was larger than mean VOL3D with all three techniques, and the difference was statistically significant (p < 0.01). The range of tumor motion and the location of the tumor affected the magnitude of the difference. For one case, all three tumor definition techniques identified volume of moderate uptake of approximately 1 mL in the hilar region on the 4D scan (SUV maximum, 3.3) but not on the 3D scan (SUV maximum, 2.3). Conclusions: In comparison to 3D PET, 4D PET may better define the full physiologic extent of moving tumors and improve radiation treatment planning for lung tumors. In addition, reduction of blurring from free-breathing images may reveal additional information regarding regional disease.

  19. Development of automated quantification of visceral and subcutaneous adipose tissue volumes from abdominal CT scans

    NASA Astrophysics Data System (ADS)

    Mensink, Sanne D.; Spliethoff, Jarich W.; Belder, Ruben; Klaase, Joost M.; Bezooijen, Roland; Slump, Cornelis H.

    2011-03-01

    This contribution describes a novel algorithm for the automated quantification of visceral and subcutaneous adipose tissue volumes from abdominal CT scans of patients referred for colorectal resection. Visceral and subcutaneous adipose tissue volumes can accurately be measured with errors of 1.2 and 0.5%, respectively. Also the reproducibility of CT measurements is good; a disadvantage is the amount of radiation. In this study the diagnostic CT scans in the work - up of (colorectal) cancer were used. This implied no extra radiation. For the purpose of segmentation alone, a low dose protocol can be applied. Obesity is a well known risk factor for complications in and after surgery. Body Mass Index (BMI) is a widely accepted indicator of obesity, but it is not specific for risk assessment of colorectal surgery. We report on an automated method to quantify visceral and subcutaneous adipose tissue volumes as a basic step in a clinical research project concerning preoperative risk assessment. The outcomes are to be correlated with the surgery results. The hypothesis is that the balance between visceral and subcutaneous adipose tissue together with the presence of calcifications in the major bloodvessels, is a predictive indicator for post - operatieve complications such as anastomotic leak. We start with four different computer simulated humanoid abdominal volumes with tissue values in the appropriate Hounsfield range at different dose levels. With satisfactory numerical results for this test, we have applied the algorithm on over a 100 patient scans and have compared results with manual segmentations by an expert for a smaller pilot group. The results are within a 5% difference. Compared to other studies reported in the literature, reliable values are obtained for visceral and subcutaneous adipose tissue areas.

  20. Quantitative assessment of emphysema from whole lung CT scans: comparison with visual grading

    NASA Astrophysics Data System (ADS)

    Keller, Brad M.; Reeves, Anthony P.; Apanosovich, Tatiyana V.; Wang, Jianwei; Yankelevitz, David F.; Henschke, Claudia I.

    2009-02-01

    Emphysema is a disease of the lungs that destroys the alveolar air sacs and induces long-term respiratory dysfunction. CT scans allow for imaging of the anatomical basis of emphysema and for visual assessment by radiologists of the extent present in the lungs. Several measures have been introduced for the quantification of the extent of disease directly from CT data in order to add to the qualitative assessments made by radiologists. In this paper we compare emphysema index, mean lung density, histogram percentiles, and the fractal dimension to visual grade in order to evaluate the predictability of radiologist visual scoring of emphysema from low-dose CT scans through quantitative scores, in order to determine which measures can be useful as surrogates for visual assessment. All measures were computed over nine divisions of the lung field (whole lung, individual lungs, and upper/middle/lower thirds of each lung) for each of 148 low-dose, whole lung scans. In addition, a visual grade of each section was also given by an expert radiologist. One-way ANOVA and multinomial logistic regression were used to determine the ability of the measures to predict visual grade from quantitative score. We found that all measures were able to distinguish between normal and severe grades (p<0.01), and between mild/moderate and all other grades (p<0.05). However, no measure was able to distinguish between mild and moderate cases. Approximately 65% prediction accuracy was achieved from using quantitative score to predict visual grade, with 73% if mild and moderate cases are considered as a single class.

  1. Influence of scan setting selections on root canal visibility with cone beam CT

    PubMed Central

    Hassan, BA; Payam, J; Juyanda, B; van der Stelt, P; Wesselink, PR

    2012-01-01

    Objectives The aim of this study was to assess the influence of scan setting selection, including field of view (FOV) ranging from small to large, number of projections and scan modes on the visibility of the root canal with cone beam CT (CBCT). Methods One human mandible cadaver was scanned with CBCT (Accuitomo 170; J Morita MPG Corp., Kyoto, Japan) using six different FOVs (4×4 cm, 6×6 cm, 8×8 cm, 10×10 cm, 14×10 cm and 17×12 cm) with either 360 or 180 projections in standard and high resolution. The right canine was selected for evaluation. Ten observers independently assessed the visibility of the canal space and overall image quality on a five-point scale. Results The results indicate that both selections of FOV and number of projections have significant influence on root canal visibility (p = 0.0001), whereas scan mode, whether standard or high resolution, was less relevant (p = 0.34). Conclusions The smallest FOV available should always be used for endodontic applications, and it is not recommended to reduce the number of projections to 180. Using the standard scan mode instead of high resolution does not negatively influence the visibility of the root canal space and is therefore recommended. PMID:23166361

  2. Metastatic Renal Cell Carcinoma in the Thyroid Gland and Pancreas Showing Uptake on 68Ga DOTATATE PET/CT Scan.

    PubMed

    Kanthan, Gowri L; Schembri, Geoffrey Paul; Samra, Jaswinder; Roach, Paul; Hsiao, Edward

    2016-07-01

    Ga DOTATATE PET/CT is an imaging technique used in the diagnosis of neuroendocrine tumors. We report a case of 66-year-old woman with a history of surgically removed renal cell carcinoma who presented for a DOTATATE PET/CT scan to characterize a newly diagnosed pancreatic lesion. DOTATATE-avid lesions were identified in the thyroid gland and pancreas. Subsequent biopsy confirmed the diagnosis of metastatic renal cell carcinoma at both sites. It is important to be aware that tumors other than neuroendocrine tumors may also show uptake on DOTATATE PET/CT scan. A biopsy may be required if lesions are identified at atypical sites. PMID:27055137

  3. An Adaptive-Tabu GA for Registration of CT and Surface Laser Scan.

    PubMed

    Lee, Jiann-Der; Huang, Jau-Hua; Huang, Chung-Hsien; Liu, Li-Chang

    2005-01-01

    An adaptive-tabu GA (Genetic Algorithm) method is proposed to improve some traditional GA methods in the registration of computer tomography (CT) and surface laser scan. In this method, the adaptive memory structure and search strategy of Tabu Search (TS) with the modified chromosome crossover and adaptive mutation are proposed to increase the convergence speed and accuracy of the fitness function. This registration method can be used on non-fiducial stereo-tactic brain surgeries to assist surgeons to diagnose and treat brain diseases. PMID:17280970

  4. Muscle CT scan findings in McLeod syndrome and chorea-acanthocytosis.

    PubMed

    Ishikawa, S; Tachibana, N; Tabata, K I; Fujimori, N; Hayashi, R I; Takahashi, J; Ikeda, S I; Hanyu, N

    2000-07-01

    Computed tomography (CT) scans of lower leg muscles reveal a selective pattern of fat infiltration in the posterior compartment with spared gracilis, semitendinosus, and the lateral head of the gastrocnemius in both McLeod syndrome and chorea-acanthocytosis, which are disorders characterized by the presence of circulating acanthocytes. The selectivity of affected muscles indicates that late onset and slowly progressive muscular atrophy in both diseases could be a consequence of primary myopathy. Asymmetrical muscle involvement may be seen during the process of degeneration only in McLeod syndrome, however, and may be helpful in distinguishing this disease from chorea-acanthocytosis. PMID:10883007

  5. Reproducibilty test of ferrous xylenol orange gel dose response with optical cone beam CT scanning

    NASA Astrophysics Data System (ADS)

    Jordan, K.; Battista, J.

    2004-01-01

    Our previous studies of ferrous xylenol orange gelatin gel have revealed a spatial dependence to the dose response of samples contained in 10 cm diameter cylinders. Dose response is defined as change in optical attenuation coefficient divided by the dose (units cm-1 Gy-1). This set of experiments was conducted to determine the reproducibility of our preparation, irradiation and full 3D optical cone beam CT scanning. The data provided an internal check of a larger storage time-dose response dependence study.

  6. Preliminary evaluation of optical CT scanning versus MRI for nPAG gel dosimetry: The Ghent experience

    NASA Astrophysics Data System (ADS)

    Vandecasteele, Jan; DeDeene, Yves

    2009-05-01

    The aim of this study was to evaluate fast laser-scanning optical CT versus MRI for an nPAG gel dosimeter in terms of accuracy and precision. Three small cylindrical volumetric gel phantoms were fabricated and irradiated with photon beams. The gel dosimeters were scanned with an MR scanner and an in house developed laser scanning optical CT scanner. A comparison between MRI and optical CT scanning was performed based on the reconstructed images. Preliminary results show a fair correspondence in the MRI acquired and optical CT acquired dose maps. Still, ringing artifacts contaminate the reconstructed optical CT images. These may be related to sub-pixel misalignments between the blank projection and the acquired transmission projection of the gel phantom. Another artifact may be caused by refraction near the edges of the field. Further optimisation of our optical CT scanner is required to obtain the same accuracy as with MRI. To make a comparison between the two imaging modalities in terms of precision, the intrinsic dose precision on readout (IPD) was calculated which is independent of spatial resolution and acquisition time. It is shown that optical CT has a better intrinsic dose precision.

  7. The pros and cons of intraoperative CT scan in evaluation of deep brain stimulation lead implantation: A retrospective study

    PubMed Central

    Servello, Domenico; Zekaj, Edvin; Saleh, Christian; Pacchetti, Claudio; Porta, Mauro

    2016-01-01

    Background: Deep brain stimulation (DBS) is an established therapy for movement disorders, such as Parkinson's disease (PD), dystonia, and tremor. The efficacy of DBS depends on the correct lead positioning. The commonly adopted postoperative radiological evaluation is performed with computed tomography (CT) scan and/or magnetic resonance imaging (MRI). Methods: We conducted a retrospective study on 202 patients who underwent DBS from January 2009 to October 2013. DBS indications were PD, progressive supranuclear palsy, tremor, dystonia, Tourette syndrome, obsessive compulsive disorder, depression, and Huntington's disease. Preoperatively, all patients underwent brain MRI and brain CT scan with the stereotactic frame positioned. The lead location was confirmed intraoperatively with CT. The CT images were subsequently transferred to the Stealth Station Medtronic and merged with the preoperative planning. On the first or second day after, implantation we performed a brain MRI to confirm the correct position of the lead. Results: In 14 patients, leads were in suboptimal position after intraoperative CT scan positioning. The cases with alteration in the Z-axis were corrected immediately under fluoroscopic guidance. In all the 14 patients, an immediate repositioning was done. Conclusions: Based on our data, intraoperative CT scan is fast, safe, and a useful tool in the evaluation of the position of the implanted lead. It also reduces the patient's discomfort derived from the transfer of the patient from the operating room to the radiological department. However, intraoperative CT should not be considered as a substitute for postoperative MRI. PMID:27583182

  8. Progressive massive fibrosis developing after brief coal dust exposure: evaluation with CT scanning and radionuclide angiocardiography.

    PubMed

    Williams, T J; Raval, B; Ahmad, D

    1980-01-01

    Two patients are described who developed progressive massive fibrosis (PMF) after exposure to coal dust for only four and seven years, respectively, in Belgian coal mines in the post-war period. It seems likely from consideration of epidemiological data that these men were exposed to massive concentrations of coal dust during their time in the mines. In one patient in a computerized tomography scan clearly showed the extent of the PMF and brought out the degree of calcification in the center of the masses. Radionuclide angiocardiographic evaluation showed depressed right ventricular function which is probably a result of pulmonary hypertension, and also showed marked distortion of the pulmonary vascular bed. It is believed that these are the first reported instances of CT scanning and radionuclide angiocardiography in this condition. PMID:7354409

  9. Implemented myeloma management with whole-body low-dose CT scan: a real life experience.

    PubMed

    Mangiacavalli, Silvia; Pezzatti, Sara; Rossini, Fausto; Doni, Elisa; Cocito, Federica; Bolis, Silvia; Corso, Alessandro

    2016-07-01

    A total of 318 consecutive myeloma patients underwent whole-body low-dose CT scan (WBLDCT) at baseline and during follow-up as a radiological assessment of lytic lesions in place of skeletal X-ray survey. After WBLDCT baseline assessment, 60% had bone involvement. The presence of lytic lesions represented the only met CRAB (hyperCalcaemia, Renal insufficiency, Anaemia, Bone lesions) criteria in 29% of patients. Patients presenting with extramedullary masses were 10%. Radiological progression was documented in 9% of the population with available follow-up. Additional pathological incidental findings were detected in 28 patients (14.5%), most located in the chest region (68%). In conclusion, our real-life data shows that WBLDCT scan represents a reliable imaging tool for decision-making process for multiple myeloma management in different disease phases, providing significant additional information on the presence of soft tissues plasmacytomas detection as well as the presence of pathological incidental findings. PMID:26788613

  10. Computerized lung nodule detection on screening CT scans: performance on juxta-pleural and internal nodules

    NASA Astrophysics Data System (ADS)

    Sahiner, Berkman; Hadjiiski, Lubomir M.; Chan, Heang-Ping; Zhou, Chuan; Wei, Jun

    2006-03-01

    We are developing a computer-aided detection (CAD) system for lung nodules in thoracic CT volumes. Our CAD system includes an adaptive 3D pre-screening algorithm to segment suspicious objects, and a false-positive (FP) reduction stage to classify the segmented objects as true nodules or normal lung structures. We found that the effectiveness of the FP reduction stage was limited by the different characteristics of the objects in the internal and the juxta-pleural (JP) regions. The purpose of this study was to evaluate object characteristics in the internal and JP regions of a lung CT scan, and to develop different FP reduction classifiers for JP and internal objects. Our FP reduction technique utilized shape, grayscale, and gradient features, as well as the scores of a newly-developed neural network trained on the eigenvalues of the Hessian matrix in a volume of interest containing the suspicious object. We designed an algorithm to automatically label the objects as internal or JP. Based on a training set of 75 CT scans containing internal and JP nodules, two FP classifiers were trained separately for objects in the two types of lung regions. The system performance was evaluated on an independent test set of 27 low dose screening scans. An experienced chest radiologist identified 64 solid nodules (mean diameter: 5.3 mm, range: 3.0-12.9 mm) on the test cases, of which 33 were internal and 31 were JP. Our adaptive 3D prescreening algorithm detected 28 internal and 29 JP nodules. At 80% sensitivity, the average number of FPs was 3.9 and 9.7 in the internal and JP regions per scan, respectively. In comparison, a classifier designed to work on both types of nodules had an average of 29.4 FPs per scan at the same sensitivity. Our results indicate that it is more effective to use two different classifiers for JP and internal nodules because of their different characteristics. FPs in the JP region were more difficult to distinguish from true nodules. Further investigation

  11. Extracting information from previous full-dose CT scan for knowledge-based Bayesian reconstruction of current low-dose CT images

    PubMed Central

    Zhang, Hao; Han, Hao; Liang, Zhengrong; Hu, Yifan; Liu, Yan; Moore, William; Ma, Jianhua; Lu, Hongbing

    2015-01-01

    Markov random field (MRF) model has been widely employed in edge-preserving regional noise smoothing penalty to reconstruct piece-wise smooth images in the presence of noise, such as in low-dose computed tomography (LdCT). While it preserves edge sharpness, its regional smoothing may sacrifice tissue image textures, which have been recognized as useful imaging biomarkers, and thus it may compromise clinical tasks such as differentiating malignant vs. benign lesions, e.g., lung nodules or colon polyps. This study aims to shift the edge-preserving regional noise smoothing paradigm to texture-preserving framework for LdCT image reconstruction while retaining the advantage of MRF’s neighborhood system on edge preservation. Specifically, we adapted the MRF model to incorporate the image textures of muscle, fat, bone, lung, etc. from previous full-dose CT (FdCT) scan as a priori knowledge for texture-preserving Bayesian reconstruction of current LdCT images. To show the feasibility of the proposed reconstruction framework, experiments using clinical patient scans were conducted. The experimental outcomes showed a dramatic gain by the a priori knowledge for LdCT image reconstruction using the commonly-used Haralick texture measures. Thus, it is conjectured that the texture-preserving LdCT reconstruction has advantages over the edge-preserving regional smoothing paradigm for texture-specific clinical applications. PMID:26561284

  12. Pregnant female anthropometry from ct scans for finite element model development.

    PubMed

    Loftis, Kathryn; Halsey, Michael; Anthony, Evelyn; Duma, Stefan M; Stitzel, Joel

    2008-01-01

    In this study, anthropometry data is collected from a CT scan of a pregnant abdomen at 32 weeks gestation. Over 1500 fetal losses occur each year in the United States due to motor vehicles crashes. Pregnant occupants involved in motor vehicle crashes are at risk for pregnancy-specific injuries. Masks of the fetus, uterus, placenta, and each of the abdominal organs are created by segmentation of the CT slices and three-dimensional volume renderings are formed. The volume and Hounsfield unit ranges for the masks of each abdominal organ are calculated. The total volume of the uterus in the 3rd trimester is measured as 3378 cm3. By measuring the length of bones on the fetal skeleton from CT slices and the 3D rendering, the gestational age of the fetus is estimated to be 32 weeks by comparison with literature values. Measurements of each of the abdominal organs are also obtained from the 3D rendering to create a blueprint of the pregnant anatomy. The masks developed and the anthropometric measurements taken will be used to develop a more accurate FE model of the pregnant female for use in the research and development in academia, industry, and government. PMID:19141941

  13. Three-dimensional dosimetry of small megavoltage radiation fields using radiochromic gels and optical CT scanning

    NASA Astrophysics Data System (ADS)

    Babic, Steven; McNiven, Andrea; Battista, Jerry; Jordan, Kevin

    2009-04-01

    The dosimetry of small fields as used in stereotactic radiotherapy, radiosurgery and intensity-modulated radiation therapy can be challenging and inaccurate due to partial volume averaging effects and possible disruption of charged particle equilibrium. Consequently, there exists a need for an integrating, tissue equivalent dosimeter with high spatial resolution to avoid perturbing the radiation beam and artificially broadening the measured beam penumbra. In this work, radiochromic ferrous xylenol-orange (FX) and leuco crystal violet (LCV) micelle gels were used to measure relative dose factors (RDFs), percent depth dose profiles and relative lateral beam profiles of 6 MV x-ray pencil beams of diameter 28.1, 9.8 and 4.9 mm. The pencil beams were produced via stereotactic collimators mounted on a Varian 2100 EX linear accelerator. The gels were read using optical computed tomography (CT). Data sets were compared quantitatively with dosimetric measurements made with radiographic (Kodak EDR2) and radiochromic (GAFChromic® EBT) film, respectively. Using a fast cone-beam optical CT scanner (Vista™), corrections for diffusion in the FX gel data yielded RDFs that were comparable to those obtained by minimally diffusing LCV gels. Considering EBT film-measured RDF data as reference, cone-beam CT-scanned LCV gel data, corrected for scattered stray light, were found to be in agreement within 0.5% and -0.6% for the 9.8 and 4.9 mm diameter fields, respectively. The validity of the scattered stray light correction was confirmed by general agreement with RDF data obtained from the same LCV gel read out with a laser CT scanner that is less prone to the acceptance of scattered stray light. Percent depth dose profiles and lateral beam profiles were found to agree within experimental error for the FX gel (corrected for diffusion), LCV gel (corrected for scattered stray light), and EBT and EDR2 films. The results from this study reveal that a three-dimensional dosimetry method

  14. Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters.

    PubMed

    Xu, Y; Wuu, Cheng-Shie; Maryanski, Marek J

    2010-02-01

    The dose response of the BANG 3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurements on the 18 glass vials irradiated with graded doses from 0 to 4 Gy using 6 or 10 MV large field irradiations; (b) optical-CT scanning of Barex cylinders irradiated with graded doses (0.5, 1, 1.5, and 2 Gy) from four adjacent 4 x 4 cm2 photon fields or 6 x 6 cm2 electron fields; and (c) percent depth dose (PDD) comparison of optical-CT scans with ion chamber measurements for 6 x 6 cm2, 12 and 16 MeV electron fields. The dose response of the BANG3 gel was found to be linear and energy independent within the uncertainties of the experimental methods (about 3%). The slopes of the linearly fitted dose response curves (dose sensitivities) from the four field irradiations (0.0752 +/- 3%, 0.0756 +/- 3%, 0.0767 +/- 3%, and 0.0759 +/- 3% cm(-1) Gy(-1)) and the PDD matching methods (0.0768 +/- 3% and 0.0761 +/- 3% cm(-1) Gy(-1)) agree within 2.2%, indicating a good reproducibility of the gel dose response within phantoms of the same geometry. The dose sensitivities from the glass vial approach are different from those of the cylindrical Barex phantoms by more than 30%, owing probably to the difference in temperature inside the two types of phantoms during gel formation and irradiation, and possible oxygen contamination of the glass vial walls. The dose response curve obtained from the PDD matching approach with 16 MeV electron field was used to calibrate the gel phantom irradiated with the 12 MeV, 6 x 6 cm2 electron field. Three-dimensional dose distributions from the gel measurement

  15. Risk stratification of non-contrast CT beyond the coronary calcium scan

    PubMed Central

    Madaj, Paul; Budoff, Matthew J.

    2014-01-01

    Coronary artery calcification (CAC) is a well-known marker for coronary artery disease and has important prognostic implications. CAC is able to provide clinicians with a reliable source of information related to cardiovascular atherosclerosis, which carries incremental information beyond Framingham risk. However, non-contrast scans of the heart provide additional information beyond the Agatston score. These studies are also able to measure various sources of fat, including intrathoracic (eg, pericardial or epicardial) and hepatic, both of which are thought to be metabolically active and linked to increased incidence of subclinical atherosclerosis as well as increased prevalence of type 2 diabetes. Testing for CAC is also useful in identifying extracoronary sources of calcification. Specifically, aortic valve calcification, mitral annular calcification, and thoracic aortic calcium (TAC) provide additional risk stratification information for cardiovascular events. Finally, scanning for CAC is able to evaluate myocardial scaring due to myocardial infarcts, which may also add incremental prognostic information. To ensure the benefits outweigh the risks of a scanning for CAC for an appropriately selected asymptomatic patient, the full utility of the scan should be realized. This review describes the current state of the art interpretation of non-contrast cardiac CT, which clinically should go well beyond coronary artery Agatston scoring alone. PMID:22981856

  16. A knowledge-based system paradigm for automatic interpretation of CT scans.

    PubMed

    Natarajan, K; Cawley, M G; Newell, J A

    1991-01-01

    The interpretation of X-ray CT scans is a task which relies on specialized medical expertise, comprising anatomical, modality-dependent, non-visual and radiological knowledge. Most medical imaging techniques generate a single scan or sequence of two-dimensional scans. The radiologist's experience is gained by interpreting two-dimensional scans. The more complex three-dimensional anatomical knowledge becomes significant only when non-standard slice orientations are used. Hence, implicit in the radiologist's knowledge is the appearance of anatomical structures in standard two-dimensional planes, transverse, sagittal and coronal. That is, position with respect to both a coordinate reference system and other structures; intensity ranges for tissue types; contrast between structures; and size within the slices. Further to this, neurological landmarking is used to establish points of reference, i.e. more easily identifiable structures are first found and subsequent hypotheses are formed. With this in mind we have developed a knowledge-based system paradigm that partitions an image by applying the domain-dependent knowledge necessary (1) to set constraints on region-based segmentation and (2) to make explicit the expectation of the appearance of the anatomy under the imaging modality for use in the region grouping phase. This paradigm affords both expectation- and event-driven segmentation by representing grouping knowledge as production rules. PMID:1921561

  17. Evaluation of image and dose according to I-dose technique when performing a CT scan

    NASA Astrophysics Data System (ADS)

    Ryu, S. W.; Lee, H. K.; Cho, J. H.

    2015-06-01

    In this study, we applied the iterative reconstruction technique to improve image quality (I-dose) and evaluated its usability by analyzing the quality of the resulting image and evaluating the dose. To perform the scans, we fixed the uniform module (CTP 486's section) 4 on the table of the computed tomography (CT) device with the American association of physicists in medicine (AAPM) phantom and located it in the center where the X-rays could be generated by using a razor beam. Then, we set up the conditions of 120 kilovoltage peak (kVp), 150 milliampere second (mAs), collimation 4 × 0.625 mm, and a standard YA (Y-Sharp) filter. Next, we formed two groups: Group A in which I-dose was not applied and Group B in which I-dose was applied. According to the rod in the middle, after fixing the location of (A) at 12 o'clock, (B) at 3 o'clock, (C) at 6 o'clock, and (D) at 9 o'clock to evaluate the image quality, the CT number was measured and the noise level was analyzed. Using the AAPM phantom with doses of 50, 100, 200, 250, and 300 mAs by 80, 100, and 120 kVp, a dose analysis was performed. After scanning, the CT numbers and noise level were measured 20 times as a function of the I-dose levels (1-7). After applying I-dose at 6, 9, 12, and 3 o'clock, when a higher I-dose was applied, a lower noise level was measured. As a result, it was found that when applying I-dose to the AAPM phantom, the higher the level of I-dose, the lower the level of noise. When applying I-dose, the dose can be reduced by 60%. When I-dose is applied when taking CT scans in a clinical study, it is possible to lower the dose and lower the noise level.

  18. The use and benefit of stereology in choosing a CT scanning protocol for the lung

    NASA Astrophysics Data System (ADS)

    Markowitz, Zvi; Loew, Murray H.; Reinhardt, Joseph M.

    2005-04-01

    When a patient is examined at different times using different protocols, how can we know whether the observed differences in the area or volume estimate are due to the patient, the protocol, or both? Specifically, we ask what is the smallest difference in lung volume that can be computed reliably when two sets of CT data are acquired by varying the number and thickness of the slices, but while holding constant the in-plane resolution. The accuracy and precision of the total lung volume estimates are calculated based on the principles of stereology using uniform design sampling. Comparisons of the lung volume estimate based on fewer slices using stereological principles are employed. A formal test made of the hypothesis that the use of fewer slices can yield satisfactory precision of the lung estimate. It is known that estimation of lung volume based on CT images is sensitive to the acquisition parameters used during scanning: dose, scan time, number of cross-sectional slices, and slice collimation. Those parameters are very different depending on the lung examination required: routine studies or high-resolution detailed studies. Thus, if different protocols are to be used confidently for volume estimation, it is important to understand the factors that influence volume estimate accuracy and to provide the associated confidence intervals for the measurements.

  19. The relationship of pineal calcification to cerebral atrophy on CT scan in multiple sclerosis.

    PubMed

    Sandyk, R; Awerbuch, G I

    1994-05-01

    Calcification is a known morphological feature of the pineal gland. The mechanisms underlying the development of pineal calcification (PC) are elusive although there is experimental evidence that calcification may be a marker of the past secretory activity of the gland and/or of degeneration. The increased incidence of PC with aging suggests that it may reflect cerebral degenerative changes as well. In a recent Editorial in this Journal it was proposed that the pineal gland is implicated in the pathogenesis of multiple sclerosis (MS). Cerebral atrophy, which can be demonstrated on CT scan, is a common feature of MS resulting from demyelination and gliosis. If PC is a marker of a cerebral degenerative process, then one would expect a higher incidence of calcification of the gland in patients with cerebral atrophy compared to those without cerebral atrophy. To test this hypothesis, we studied the incidence of PC on CT scan in a cohort of 48 MS patients, 21 of whom had cerebral atrophy. For the purpose of comparison, we also assessed the incidence of choroid plexus calcification (CPC) in relation to cerebral atrophy. PC was found in 42 patients (87.5%) and its incidence in patients with cerebral atrophy was significantly higher compared to the incidence in patients without cerebral atrophy (100% vs. 77.7%; p < .025). In contrast, CPC was unrelated to cerebral atrophy or to PC thus supporting the notion of a specific association between the pineal gland and the pathogenesis of MS.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7960471

  20. Auditory profile and high resolution CT scan in autism spectrum disorders children with auditory hypersensitivity.

    PubMed

    Thabet, Elsaeid M; Zaghloul, Hesham S

    2013-08-01

    Autism is the third most common developmental disorder, following mental retardationand cerebral palsy. ASD children have been described more often as beingpreoccupied with or agitated by noise. The aim of this study was to evaluate theprevalence and clinical significance of semicircular canal dehiscence detected on CTimages in ASD children with intolerance to loud sounds in an attempt to find ananatomical correlate with hyperacusis.14 ASD children with auditory hypersensitivity and 15 ASD children without auditoryhypersensitivity as control group age and gender matched were submitted to historytaking, otological examination, tympanometry and acoustic reflex thresholdmeasurement. ABR was done to validate normal peripheral hearing and integrity ofauditory brain stem pathway. High resolution CT scan petrous and temporal boneimaging was performed to all participated children. All participants had normal hearingsensitivity in ABR testing. Absolute ABR peak waves of I and III showed no statisticallysignificant difference between the two groups, while absolute wave V peak andinterpeak latencies I-V and III-V were shorter in duration in study group whencompared to the control group. CT scans revealed SSCD in 4 out of 14 of the studygroup (29%), the dehiscence was bilateral in one patient and unilateral in threepatients. None of control group showed SSCD. In conclusion, we have reportedevidence that apparent hypersensitivity to auditory stimuli (short conduction time in ABR) despite the normal physiological measures in ASD children with auditoryhypersensitivity can provide a clinical clue of a possible SSCD. PMID:23580033

  1. Angiogenesis in tissue-engineered nerves evaluated objectively using MICROFIL perfusion and micro-CT scanning

    PubMed Central

    Wang, Hong-kui; Wang, Ya-xian; Xue, Cheng-bin; Li, Zhen-mei-yu; Huang, Jing; Zhao, Ya-hong; Yang, Yu-min; Gu, Xiao-song

    2016-01-01

    Angiogenesis is a key process in regenerative medicine generally, as well as in the specific field of nerve regeneration. However, no convenient and objective method for evaluating the angiogenesis of tissue-engineered nerves has been reported. In this study, tissue-engineered nerves were constructed in vitro using Schwann cells differentiated from rat skin-derived precursors as supporting cells and chitosan nerve conduits combined with silk fibroin fibers as scaffolds to bridge 10-mm sciatic nerve defects in rats. Four weeks after surgery, three-dimensional blood vessel reconstructions were made through MICROFIL perfusion and micro-CT scanning, and parameter analysis of the tissue-engineered nerves was performed. New blood vessels grew into the tissue-engineered nerves from three main directions: the proximal end, the distal end, and the middle. The parameter analysis of the three-dimensional blood vessel images yielded several parameters, including the number, diameter, connection, and spatial distribution of blood vessels. The new blood vessels were mainly capillaries and microvessels, with diameters ranging from 9 to 301 μm. The blood vessels with diameters from 27 to 155 μm accounted for 82.84% of the new vessels. The microvessels in the tissue-engineered nerves implanted in vivo were relatively well-identified using the MICROFIL perfusion and micro-CT scanning method, which allows the evaluation and comparison of differences and changes of angiogenesis in tissue-engineered nerves implanted in vivo. PMID:26981108

  2. CT Scan Mapping of Splenic Flexure in Relation to Spleen and its Clinical Implications.

    PubMed

    Saber, Alan A; Dervishaj, Ornela; Aida, Samer S; Christos, Paul J; Dakhel, Mahmoud

    2016-05-01

    Splenic flexure mobilization is a challenging step during left colon resection. The maneuver places the spleen at risk for injury. To minimize this risk, we conducted this study for CT scan mapping of splenic flexure in relation to the spleen. One hundred and sixty CT scans of abdomen were reviewed. The level of the splenic flexure was determined in relation to hilum and lower pole of spleen. These levels were compared with patient demographics. Statistical analysis was performed using Fisher's exact test. The splenic flexure was above the hilum of the spleen in 95 patients (67.86%), at the splenic hilum level in 11 patents (7.88%), between the hilum and lower pole of the spleen in 12 (8.57%), at the lower pole of the spleen in 15 (10.7%) patients and 7 (5%) patients has a splenic flexure that lied below the lower pole of the spleen. Patient demographics showed no statistical significance in regard to splenic flexure location. Splenic flexure lies above the hilum of the spleen in majority of patients. This should be considered as part of operative strategies for left colon resection. PMID:27215722

  3. Automated segmentation and tracking of coronary arteries in ECG-gated cardiac CT scans

    NASA Astrophysics Data System (ADS)

    Zhou, Chuan; Chan, Heang-Ping; Chughtai, Aamer; Patel, Smita; Agarwal, Prachi; Hadjiiski, Lubomir M.; Sahiner, Berkman; Wei, Jun; Ge, Jun; Kazerooni, Ella A.

    2008-03-01

    Cardiac CT has been reported to be an effective means for clinical diagnosis of coronary artery plaque disease. We are investigating the feasibility of developing a computer-assisted image analysis (CAA) system to assist radiologist in detection of coronary artery plaque disease in ECG-gated cardiac CT scans. The heart region was first extracted using morphological operations and an adaptive EM thresholding method. Vascular structures in the heart volume were enhanced by 3D multi-scale filtering and analysis of the eigenvalues of Hessian matrices using a vessel enhancement response function specially designed for coronary arteries. The enhanced vascular structures were then segmented by an EM estimation method. Finally, our newly developed 3D rolling balloon vessel tracking method (RBVT) was used to track the segmented coronary arteries. Starting at two manually identified points located at the origins of left and right coronary artery (LCA and RCA), the RBVT method moved a sphere of adaptive diameter along the vessels, tracking the vessels and identifying its branches automatically to generate the left and right coronary arterial trees. Ten cardiac CT scans that contained various degrees of coronary artery diseases were used as test data set for our vessel segmentation and tracking method. Two experienced thoracic radiologists visually examined the computer tracked coronary arteries on a graphical interface to count untracked false-negative (FN) branches (segments). A total of 27 artery segments were identified to be FNs in the 10 cases, ranging from 0 to 6 FN segments in each case. No FN artery segment was found in 2 cases.

  4. Imaging Non-Specific Wrist Pain: Interobserver Agreement and Diagnostic Accuracy of SPECT/CT, MRI, CT, Bone Scan and Plain Radiographs

    PubMed Central

    Huellner, Martin W.; Bürkert, Alexander; Strobel, Klaus; Pérez Lago, María del Sol; Werner, Lennart; Hug, Urs; von Wartburg, Urs; Seifert, Burkhardt; Veit-Haibach, Patrick

    2013-01-01

    Purpose Chronic hand and wrist pain is a common clinical issue for orthopaedic surgeons and rheumatologists. The purpose of this study was 1. To analyze the interobserver agreement of SPECT/CT, MRI, CT, bone scan and plain radiographs in patients with non-specific pain of the hand and wrist, and 2. to assess the diagnostic accuracy of these imaging methods in this selected patient population. Materials and Methods Thirty-two consecutive patients with non-specific pain of the hand or wrist were evaluated retrospectively. All patients had been imaged by plain radiographs, planar early-phase imaging (bone scan), late-phase imaging (SPECT/CT including bone scan and CT), and MRI. Two experienced and two inexperienced readers analyzed the images with a standardized read-out protocol. Reading criteria were lesion detection and localisation, type and etiology of the underlying pathology. Diagnostic accuracy and interobserver agreement were determined for all readers and imaging modalities. Results The most accurate modality for experienced readers was SPECT/CT (accuracy 77%), followed by MRI (56%). The best performing, though little accurate modality for inexperienced readers was also SPECT/CT (44%), followed by MRI and bone scan (38% each). The interobserver agreement of experienced readers was generally high in SPECT/CT concerning lesion detection (kappa 0.93, MRI 0.72), localisation (kappa 0.91, MRI 0.75) and etiology (kappa 0.85, MRI 0.74), while MRI yielded better results on typification of lesions (kappa 0.75, SPECT/CT 0.69). There was poor agreement between experienced and inexperienced readers in SPECT/CT and MRI. Conclusions SPECT/CT proved to be the most helpful imaging modality in patients with non-specific wrist pain. The method was found reliable, providing high interobserver agreement, being outperformed by MRI only concerning the typification of lesions. We believe it is beneficial to integrate SPECT/CT into the diagnostic imaging algorithm of chronic wrist

  5. CT scanning carcases has no detrimental effect on the colour stability of M. longissimus dorsi from beef and sheep.

    PubMed

    Jose, C G; Pethick, D W; Jacob, R H; Gardner, G E

    2009-01-01

    This study investigated the effect of computerised tomography imaging (CT scan), for carcase composition determination, on the oxy/metmyoglobin ratio, hue and L(∗), a(∗) and b(∗) scores of M. longissimus dorsi from both beef and lamb. Beef and lamb M. longissimus dorsi were divided into four proportions and randomly allocated to one of the following treatments; CT 30 day aged; CT fresh; control 30 day aged; control fresh. Colour measurements were made over a 96h retail display period. CT scan had little effect on the colour of both lamb and beef across all colour parameters. There was a small negative affect observed in CT aged samples (P<0.05) for ratio, hue, a(∗) and b(∗) values, however these differences were so small that they are unlikely to impact upon the commercial shelf-life of the product. Other factors such as aging, species and vitamin E concentration play a much greater role in colour stability than CT. Aged M. longissimus dorsi clearly had a worse colour stability than the fresh packaged samples, while beef was a lot more colour stable than lamb. It appears that CT scan for the purpose of body composition determination will not have any commercially relevant impact on colour stability of both beef and lamb. PMID:22063980

  6. [Exposure to CT scans in childhood and long-term cancer risk: A review of epidemiological studies].

    PubMed

    Baysson, Hélène; Journy, Neige; Roué, Tristan; Ducou-Lepointe, Hubert; Etard, Cécile; Bernier, Marie-Odile

    2016-02-01

    Amongst medical exams requiring ionizing radiation, computed tomography (CT) scans are used more frequently, including in children. These CT examinations are associated with absorbed doses that are much higher than those associated with conventional radiology. In comparison to adults, children have a greater sensitivity to radiation and a longer life span with more years at cancer risks. Five epidemiological studies on cancer risks after CT scan exposure during childhood were published between 2012 and 2015. The results of these studies are consistent and show an increase of cancer risks in children who have been exposed to several CT scans. However, methodological limits due to indication bias, retrospective assessment of radiation exposure from CT scans and lack of statistical power are to be taken into consideration. International projects such as EPI-CT (Epidemiological study to quantify risks for pediatric computerized tomography and to optimize dose), with a focus on dosimetric reconstruction and minimization of bias will provide more precise results. In the meantime, available results reinforce the necessity of justification and optimization of doses. PMID:26782078

  7. NOTE: Optimization of megavoltage CT scan registration settings for thoracic cases on helical tomotherapy

    NASA Astrophysics Data System (ADS)

    Woodford, Curtis; Yartsev, Slav; Van Dyk, Jake

    2007-08-01

    This study aims to investigate the settings that provide optimum registration accuracy when registering megavoltage CT (MVCT) studies acquired on tomotherapy with planning kilovoltage CT (kVCT) studies of patients with lung cancer. For each experiment, the systematic difference between the actual and planned positions of the thorax phantom was determined by setting the phantom up at the planning isocenter, generating and registering an MVCT study. The phantom was translated by 5 or 10 mm, MVCT scanned, and registration was performed again. A root-mean-square equation that calculated the residual error of the registration based on the known shift and systematic difference was used to assess the accuracy of the registration process. The phantom study results for 18 combinations of different MVCT/kVCT registration options are presented and compared to clinical registration data from 17 lung cancer patients. MVCT studies acquired with coarse (6 mm), normal (4 mm) and fine (2 mm) slice spacings could all be registered with similar residual errors. No specific combination of resolution and fusion selection technique resulted in a lower residual error. A scan length of 6 cm with any slice spacing registered with the full image fusion selection technique and fine resolution will result in a low residual error most of the time. On average, large corrections made manually by clinicians to the automatic registration values are infrequent. Small manual corrections within the residual error averages of the registration process occur, but their impact on the average patient position is small. Registrations using the full image fusion selection technique and fine resolution of 6 cm MVCT scans with coarse slices have a low residual error, and this strategy can be clinically used for lung cancer patients treated on tomotherapy. Automatic registration values are accurate on average, and a quick verification on a sagittal MVCT slice should be enough to detect registration outliers.

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

    SciTech Connect

    Cunliffe, A; Contee, C; White, B; Justusson, J; Armato, S; Malik, R; Al-Hallaq, H

    2014-06-15

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

  9. Moving metal artifact reduction in cone-beam CT scans with implanted cylindrical gold markers

    SciTech Connect

    Toftegaard, Jakob Fledelius, Walther; Worm, Esben S.; Poulsen, Per R.; Seghers, Dieter; Huber, Michael; Brehm, Marcus; Elstrøm, Ulrik V.

    2014-12-15

    Purpose: Implanted gold markers for image-guided radiotherapy lead to streaking artifacts in cone-beam CT (CBCT) scans. Several methods for metal artifact reduction (MAR) have been published, but they all fail in scans with large motion. Here the authors propose and investigate a method for automatic moving metal artifact reduction (MMAR) in CBCT scans with cylindrical gold markers. Methods: The MMAR CBCT reconstruction method has six steps. (1) Automatic segmentation of the cylindrical markers in the CBCT projections. (2) Removal of each marker in the projections by replacing the pixels within a masked area with interpolated values. (3) Reconstruction of a marker-free CBCT volume from the manipulated CBCT projections. (4) Reconstruction of a standard CBCT volume with metal artifacts from the original CBCT projections. (5) Estimation of the three-dimensional (3D) trajectory during CBCT acquisition for each marker based on the segmentation in Step 1, and identification of the smallest ellipsoidal volume that encompasses 95% of the visited 3D positions. (6) Generation of the final MMAR CBCT reconstruction from the marker-free CBCT volume of Step 3 by replacing the voxels in the 95% ellipsoid with the corresponding voxels of the standard CBCT volume of Step 4. The MMAR reconstruction was performed retrospectively using a half-fan CBCT scan for 29 consecutive stereotactic body radiation therapy patients with 2–3 gold markers implanted in the liver. The metal artifacts of the MMAR reconstructions were scored and compared with a standard MAR reconstruction by counting the streaks and by calculating the standard deviation of the Hounsfield units in a region around each marker. Results: The markers were found with the same autosegmentation settings in 27 CBCT scans, while two scans needed slightly changed settings to find all markers automatically in Step 1 of the MMAR method. MMAR resulted in 15 scans with no streaking artifacts, 11 scans with 1–4 streaks, and 3 scans

  10. Development of a database of organ doses for paediatric and young adult CT scans in the United Kingdom

    PubMed Central

    Kim, K. P.; Berrington de González, A.; Pearce, M. S.; Salotti, J. A.; Parker, L.; McHugh, K.; Craft, A. W.; Lee, C.

    2012-01-01

    Despite great potential benefits, there are concerns about the possible harm from medical imaging including the risk of radiation-related cancer. There are particular concerns about computed tomography (CT) scans in children because both radiation dose and sensitivity to radiation for children are typically higher than for adults undergoing equivalent procedures. As direct empirical data on the cancer risks from CT scans are lacking, the authors are conducting a retrospective cohort study of over 240 000 children in the UK who underwent CT scans. The main objective of the study is to quantify the magnitude of the cancer risk in relation to the radiation dose from CT scans. In this paper, the methods used to estimate typical organ-specific doses delivered by CT scans to children are described. An organ dose database from Monte Carlo radiation transport-based computer simulations using a series of computational human phantoms from newborn to adults for both male and female was established. Organ doses vary with patient size and sex, examination types and CT technical settings. Therefore, information on patient age, sex and examination type from electronic radiology information systems and technical settings obtained from two national surveys in the UK were used to estimate radiation dose. Absorbed doses to the brain, thyroid, breast and red bone marrow were calculated for reference male and female individuals with the ages of newborns, 1, 5, 10, 15 and 20 y for a total of 17 different scan types in the pre- and post-2001 time periods. In general, estimated organ doses were slightly higher for females than males which might be attributed to the smaller body size of the females. The younger children received higher doses in pre-2001 period when adult CT settings were typically used for children. Paediatric-specific adjustments were assumed to be used more frequently after 2001, since then radiation doses to children have often been smaller than those to adults. The

  11. Detection of abdominal aortic graft infection: comparison of CT and In-labeled white blood cell scans

    SciTech Connect

    Mark, A.S.; McCarthy, S.M.; Moss, A.A.; Price, D.

    1985-02-01

    Aortic graft infections are a rare but potentially lethal complication of aortic graft surgery. The diagnosis and assessment of the extent of a graft infection is difficult on clinical grounds. A prospective study compared CT and indium-labeled white blood cell (In-WBC) scans in the diagnosis of aortic graft infection. Five patients with aortic graft infection and three patients without aortic graft infection were studied by both methods. CT correctly detected the retroperitoneal extension of the infection in three patients with groin infection; In-WBC scans diagnosed the extension only in one patient. Both CT and In-WBC were positive in two patients with aortic graft infection but no groin infection. Both studies were negative in the three patients without evidence of aortic graft infection. The study suggests that CT is more sensitive than In-WBC in evaluating the extent of aortic graft infection and should be the imaging method of choice.

  12. Emphysema in silica- and asbestos-exposed workers seeking compensation. A CT scan study.

    PubMed

    Bégin, R; Filion, R; Ostiguy, G

    1995-09-01

    It has been established that coal pneumoconiosis and confluent silicosis are associated with emphysematous changes in the lungs. In the present study, we addressed the concept of emphysema in simple silicosis and asbestosis and in workers exposed to these minerals without the pneumoconiosis. The study was done on 207 consecutive workers evaluated for possible pneumoconiosis at Québec Workman Compensation Board, who had a radiographic reading of pneumoconiosis in the category 0 or 1 of the ILO scale, and in 5 control subjects. Emphysema was detected, typed, and graded on high-resolution CT scans by three independent experienced readers. Age, work experience and industry, smoking habits, and pulmonary function test results were analyzed for possible associations. The subjects were 59 +/- 1 years of age and had mineral dust exposure averaging 26 +/- 1 years; 31 were lifetime nonsmokers and the others were either ex- or current smokers. Ninety-six workers were from primary and 111 from secondary industries and did not differ in any parameter. The CT scan readings for emphysema yielded a 63% complete agreement. In lifetime non-smokers, emphysema was seen in 1 of 20 subjects without pneumoconiosis but in 8 of 11 patients with pneumoconioses. In smokers without pneumoconioses, emphysema was present in 55% of patients with silica exposure, but 29% of patients with asbestos exposure but comparable smoking (p = 0.04). Emphysema type was equally distributed among the groups except for more paracicatricial type in confluent silicosis. Regression analyses documented that age, smoking, exposure type, and presence of pneumoconiosis were significant contribution factors. In the workers without pneumoconiosis, age, smoking, and exposure type (silica) were significant. Emphysema related best with FEV1/FVC ratio, MMEF, and DCO reductions. The prevalence of abnormality of FEV1/FVC ratio was two to five times normal and that of reduced DCO two times normal. We conclude that, in our

  13. 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

  14. A study of the short- to long-phantom dose ratios for CT scanning without table translation

    SciTech Connect

    Li, Xinhua; Zhang, Da; Liu, Bob; Yang, Jie

    2014-09-15

    Purpose: For CT scanning in the stationary-table modes, AAPM Task Group 111 proposed to measure the midpoint dose on the central and peripheral axes of sufficiently long phantoms. Currently, a long cylindrical phantom is usually not available in many clinical facilities. The use of a long phantom is also challenging because of the heavy weight. In order to shed light on assessing the midpoint dose in CT scanning without table movement, the authors present a study of the short- to long-phantom dose ratios, and perform a cross-comparison of CT dose ratios on different scanner models. Methods: The authors performed Geant4-based Monte Carlo simulations with a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare), and modeled dosimetry measurements using a 0.6 cm{sup 3} Farmer type chamber and a 10-cm long pencil ion chamber. The short (15 cm) to long (90 cm) phantom dose ratios were computed for two PMMA diameters (16 and 32 cm), two phantom axes (the center and the periphery), and a range of beam apertures (3–25 cm). The results were compared with the published data of previous studies with other multiple detector CT (MDCT) scanners and cone beam CT (CBCT) scanners. Results: The short- to long-phantom dose ratios changed with beam apertures but were insensitive to beam qualities (80–140 kV, the head and body bowtie filters) and MDCT and CBCT scanner models. Conclusions: The short- to long-phantom dose ratios enable medical physicists to make dosimetry measurements using the standard CT dosimetry phantoms and a Farmer chamber or a 10 cm long pencil chamber, and to assess the midpoint dose in long phantoms. This method provides an effective approach for the dosimetry of CBCT scanning in the stationary-table modes, and is useful for perfusion and interventional CT.

  15. A TR-induced algorithm for hot spots elimination through CT-scan HIFU simulations

    NASA Astrophysics Data System (ADS)

    Leduc, Nicolas; Okita, Kohei; Sugiyama, Kazuyasu; Takagi, Shu; Matsumoto, Yoichiro

    2011-09-01

    Although nowadays widely spread for imaging and treatments uses, HIFU techniques are still limited by the distortion of the wavefront due to refraction and reflection on the inhomogeneous media inside the human body. CT-scan Time Reversal (TR) procedure has risen as a promising candidate for focus control. A finite difference time domain parallelized code is used to provide simulations of TR-enhanced propagation through elements of the human body and implement a simple algorithm to address the issue of grating lobes, i.e secondary peaks of pressure due to natural diffraction by phased arrays and enhanced by medium heterogeneity. Using an iterative, progressive process combining secondary sound sources and independent signal summation, the primary peak is strengthened while secondary peaks are increasingly obliterated. This method supports the feasibility of precise modification and enhancement of the pressure profile in the targeted area through Time Reversal based solutions.

  16. Cerebral embolism: local CFBF and edema measured by CT scanning and Xe inhalation. [Baboons

    SciTech Connect

    Meyer, J.S.; Yamamoto, M.; Hayman, L.A.; Sakai, F.; Nakajima, S.; Armstrong, D.

    1980-01-01

    Serial CT scans were made in baboons after cerebral embolization during stable Xe inhalation for measuring local values for CBF and lambda (brain-blood partition or solubility coefficients), followed by iodine infusion for detecting blood-brain barrier (BBB) damage. Persistent zones of zero flow surrounded by reduced flow were measured predominantly in subcortical regions, which showed gross and microscopic evidence of infarction at necropsy. Overlying cortex was relatively spared. Reduced lambda values attributed to edema appeared within 3 to 5 minutes and progressed up to 60 minutes. Damage to BBB with visible transvascular seepage of iodine began to appear 1 to 1 1/2 hours after embolism. In chronic animals, lambda values were persistently reduced in areas showing histologic infarction. Contralateral hemispheric CBF increased for the first 15 minutes after embolism, followed by progressive reduction after 30 minutes (diaschisis).

  17. A fully automated non-external marker 4D-CT sorting algorithm using a serial cine scanning protocol

    NASA Astrophysics Data System (ADS)

    Carnes, Greg; Gaede, Stewart; Yu, Edward; Van Dyk, Jake; Battista, Jerry; Lee, Ting-Yim

    2009-04-01

    Current 4D-CT methods require external marker data to retrospectively sort image data and generate CT volumes. In this work we develop an automated 4D-CT sorting algorithm that performs without the aid of data collected from an external respiratory surrogate. The sorting algorithm requires an overlapping cine scan protocol. The overlapping protocol provides a spatial link between couch positions. Beginning with a starting scan position, images from the adjacent scan position (which spatial match the starting scan position) are selected by maximizing the normalized cross correlation (NCC) of the images at the overlapping slice position. The process was continued by 'daisy chaining' all couch positions using the selected images until an entire 3D volume was produced. The algorithm produced 16 phase volumes to complete a 4D-CT dataset. Additional 4D-CT datasets were also produced using external marker amplitude and phase angle sorting methods. The image quality of the volumes produced by the different methods was quantified by calculating the mean difference of the sorted overlapping slices from adjacent couch positions. The NCC sorted images showed a significant decrease in the mean difference (p < 0.01) for the five patients.

  18. Possibilities of CT Scanning as Analysis Method in Laser Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Karme, Aleksis; Kallonen, Aki; Matilainen, Ville-Pekka; Piili, Heidi; Salminen, Antti

    Laser additive manufacturing is an established and constantly developing technique. Structural assessment should be a key component to ensure directed evolution towards higher level of manufacturing. The macroscopic properties of metallic structures are determined by their internal microscopic features, which are difficult to assess using conventional surface measuring methodologies. X-ray microtomography (CT) is a promising technique for three-dimensional non-destructive probing of internal composition and build of various materials. Aim of this study is to define the possibilities of using CT scanning as quality control method in LAM fabricated parts. Since the parts fabricated with LAM are very often used in high quality and accuracy demanding applications in various industries such as medical and aerospace, it is important to be able to define the accuracy of the build parts. The tubular stainless steel test specimens were 3D modelled, manufactured with a modified research AM equipment and imaged after manufacturing with a high-power, high-resolution CT scanner. 3D properties, such as surface texture and the amount and distribution of internal pores, were also evaluated in this study. Surface roughness was higher on the interior wall of the tube, and deviation from the model was systematically directed towards the central axis. Pore distribution showed clear organization and divided into two populations; one following the polygon model seams along both rims, and the other being associated with the concentric and equidistant movement path of the laser. Assessment of samples can enhance the fabrication by guiding the improvement of both modelling and manufacturing process.

  19. Evaluation of radiation dose and image quality of CT scan for whole-body pediatric PET/CT: A phantom study

    SciTech Connect

    Yang, Ching-Ching; Liu, Shu-Hsin; Mok, Greta S. P.; Wu, Tung-Hsin

    2014-09-15

    Purpose: This study aimed to tailor the CT imaging protocols for pediatric patients undergoing whole-body PET/CT examinations with appropriate attention to radiation exposure while maintaining adequate image quality for anatomic delineation of PET findings and attenuation correction of PET emission data. Methods: The measurements were made by using three anthropomorphic phantoms representative of 1-, 5-, and 10-year-old children with tube voltages of 80, 100, and 120 kVp, tube currents of 10, 40, 80, and 120 mA, and exposure time of 0.5 s at 1.75:1 pitch. Radiation dose estimates were derived from the dose-length product and were used to calculate risk estimates for radiation-induced cancer. The influence of image noise on image contrast and attenuation map for CT scans were evaluated based on Pearson's correlation coefficient and covariance, respectively. Multiple linear regression methods were used to investigate the effects of patient age, tube voltage, and tube current on radiation-induced cancer risk and image noise for CT scans. Results: The effective dose obtained using three anthropomorphic phantoms and 12 combinations of kVp and mA ranged from 0.09 to 4.08 mSv. Based on our results, CT scans acquired with 80 kVp/60 mA, 80 kVp/80 mA, and 100 kVp/60 mA could be performed on 1-, 5-, and 10-year-old children, respectively, to minimize cancer risk due to CT scans while maintaining the accuracy of attenuation map and CT image contrast. The effective doses of the proposed protocols for 1-, 5- and 10-year-old children were 0.65, 0.86, and 1.065 mSv, respectively. Conclusions: Low-dose pediatric CT protocols were proposed to balance the tradeoff between radiation-induced cancer risk and image quality for patients ranging in age from 1 to 10 years old undergoing whole-body PET/CT examinations.

  20. The Use Of Computerized Tomographic (CT) Scans For 3-D Display And Prosthesis Construction

    NASA Astrophysics Data System (ADS)

    Mankovich, Nicholas J.; Woodruff, Tracey J.; Beumer, John

    1985-06-01

    The construction of preformed cranial prostheses for large cranial bony defects is both error prone and time consuming. We discuss a method used for the creation of cranial prostheses from automatically extracted bone contours taken from Computerized Tomographic (CT) scans. Previous methods of prosthesis construction have relied on the making of a mold directly from the region of cranial defect. The use of image processing, bone contour extraction, and three-dimensional display allowed us to create a better fitting prosthesis while reducing patient surgery time. This procedure involves direct bone margin extraction from the digital CT images followed by head model construction from serial plots of the bone margin. Three-dimensional data display is used to verify the integrity of the skull data set prior to model construction. Once created, the model is used to fabricate a custom fitting prosthesis which is then surgically implanted. This procedure is being used with patients in the Maxillofacial Prosthetic Clinic at UCLA and this paper details the technique.

  1. Fourier-based reconstruction via alternating direction total variation minimization in linear scan CT

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    In this study, we consider a novel form of computed tomography (CT), that is, linear scan CT (LCT), which applies a straight line trajectory. Furthermore, an iterative algorithm is proposed for pseudo-polar Fourier reconstruction through total variation minimization (PPF-TVM). Considering that the sampled Fourier data are distributed in pseudo-polar coordinates, the reconstruction model minimizes the TV of the image subject to the constraint that the estimated 2D Fourier data for the image are consistent with the 1D Fourier transform of the projection data. PPF-TVM employs the alternating direction method (ADM) to develop a robust and efficient iteration scheme, which ensures stable convergence provided that appropriate parameter values are given. In the ADM scheme, PPF-TVM applies the pseudo-polar fast Fourier transform and its adjoint to iterate back and forth between the image and frequency domains. Thus, there is no interpolation in the Fourier domain, which makes the algorithm both fast and accurate. PPF-TVM is particularly useful for limited angle reconstruction in LCT and it appears to be robust against artifacts. The PPF-TVM algorithm was tested with the FORBILD head phantom and real data in comparisons with state-of-the-art algorithms. Simulation studies and real data verification suggest that PPF-TVM can reconstruct higher accuracy images with lower time consumption.

  2. Scale-invariant registration of monocular endoscopic images to CT-scans for sinus surgery.

    PubMed

    Burschka, Darius; Li, Ming; Ishii, Masaru; Taylor, Russell H; Hager, Gregory D

    2005-10-01

    In this paper, we present a novel method for intra-operative registration directly from monocular endoscopic images. This technique has the potential to provide a more accurate surface registration at the surgical site than existing methods. It can operate autonomously from as few as two images and can be particularly useful in revision cases where surgical landmarks may be absent. A by-product of video registration is an estimate of the local surface structure of the anatomy, thus providing the opportunity to dynamically update anatomical models as the surgery progresses. Our approach is based on a previously presented method [Burschka, D., Hager, G.D., 2004. V-GPS (SLAM):--Vision-based inertial system for mobile robots. In: Proceedings of ICRA, 409-415] for reconstruction of a scaled 3D model of the environment from unknown camera motion. We use this scaled reconstruction as input to a PCA-based algorithm that registers the reconstructed data to the CT data and recovers the scale and pose parameters of the camera in the coordinate frame of the CT scan. The result is used in an ICP registration step to refine the registration estimates. The details of our approach and the experimental results with a phantom of a human skull and a head of a pig cadaver are presented in this paper. PMID:16009593

  3. Combination of detection and estimation tasks using channelized scanning linear observer for CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.

    2015-03-01

    Maintaining or even improving image quality while lowering patient dose is always the desire in clinical CT imaging. Iterative reconstruction (IR) algorithms have been designed to help reduce dose and/or provide better image quality. In this work, the channelized scanning linear observer (CSLO) is applied to study the combination of detection and estimation task performance using CT image data. The purpose of this work is to design a task-­-based approach to quantitatively evaluate image-­-quality for different reconstruction algorithms. Low-­-contrast objects embedded in head-­-size and body-­-size phantoms are imaged multiple times and reconstructed by FBP and an IR algorithm for this study. Independent signal present and absent ROIs cropped from images are channelized by Difference of Gauss channels for CSLO training and testing. Estimation receiver operating characteristic (EROC) curves and the area under EROC curve (EAUC) are calculated by CSLO as the figure of merit. The One-­- Shot method is used to compute the variance of the EAUC values. Results suggest that the IR algorithm studied in this work could efficiently reduce the dose approximately 54% to achieve an image quality comparable to conventional FBP reconstruction for the combined detection and estimation tasks.

  4. Correlation of CT scanning and pathologic features of ophthalmic Graves' disease.

    PubMed

    Trokel, S L; Jakobiec, F A

    1981-06-01

    Correlating the CT scan features of patients with orbital Graves' disease with histopathologic observations allows one to focus more specifically on the distinguishing features of this disease with future research implications. Both CT scanning and pathologic studies have shown clearly that the extraocular muscles are the primary focus of the disease. Swelling of the extraocular muscles generally occurs within their bellys with sparing of the tendons. This contrast with idiopathic inflammation of the muscles or myositis, which tends to involve the tendon as well. All of the associated findings in orbital Graves' disease probably flow from the enlarged volume of the extraocular muscles: proptosis, bowing of the medial lamina papyracea to accommodate the swollen belly of the medial rectus muscle, venous engorgement from stasis induced by direct compression of the orbital venous drainage, conjunctival and lid swelling, and lacrimal gland enlargement. Both radiographic and pathologic changes in the orbital fat are secondary and comparatively insignificant. While there appears to be no selective inflammation of the optic nerve meninges or the perineural connective tissues, enlargement of the extraocular muscle bellys where they converge at the crowded orbital apex brings about compression of the optic nerve, impairs its function, and causes visual decrease. Lymphocytic and plasmacytic infiltration along with edema within the endomysium of the extraocular muscles leads to the activation of fibroblasts with the production of acid mucopolysaccharides and progressive fibrosis. It is not known what attracts the lymphocytes to the extraocular muscles, why certain extraocular muscles are affected preferentially, why the disease may be asymmetrically unilateral, and whether a defect in T cell or B cell functions (or both) is immunologically at fault. PMID:6894976

  5. Comparative analysis of the radiation shield effect in an abdominal CT scan

    NASA Astrophysics Data System (ADS)

    Kim, Seon-Chil; Kim, Young-Jae; Lee, Joon-Seok; Dong, Kyung-Rae; Chung, Woon-Kwan; Lim, Chang-Seon

    2014-03-01

    This study measured and compared the dose on the eyeballs and the thyroid with and without the use of a shield by applying the abdominal examination protocol used in an actual examination to a 64-channel computed tomography (CT) scan. A dummy phantom manufactured from acryl was used to measure the dose to the eyeballs and the thyroid of a patient during a thoraco-abdominal CT scan. The dose was measured using three dosimeters (optically-stimulated luminescence dosimeter (OSLD), thermoluminescence dosimeter (TLD) and photoluminescence dosimeter (PLD)) attached to the surfaces of three parts (left and right eyeballs and thyroid) in a phantom with and without the use of a shield for the eyeballs and the thyroid. Two types of shields (1-mm barium shielding sheet and 1-mm tungsten shielding sheet) were used for the measurements. The goggles and the lead shield, which are normally used in clinical practice, were used to compare the shield ratios of the shields. According to the results of the measurements made by using the OSLD, the shield ratios of the barium and the tungsten sheets were in the range of 34-36%. The measurements made by using the TLD showed that the shield ratio of the barium sheet was 6.25% higher than that of the tungsten sheet. When the PLD was used for the measurement, the shield ratio of the barium sheet was 33.34%, which was equivalent to that of the tungsten sheet. These results confirmed that the cheap barium sheet had a better shielding effect than the expensive tungsten sheet.

  6. Heart region segmentation from low-dose CT scans: an anatomy based approach

    NASA Astrophysics Data System (ADS)

    Reeves, Anthony P.; Biancardi, Alberto M.; Yankelevitz, David F.; Cham, Matthew D.; Henschke, Claudia I.

    2012-02-01

    Cardiovascular disease is a leading cause of death in developed countries. The concurrent detection of heart diseases during low-dose whole-lung CT scans (LDCT), typically performed as part of a screening protocol, hinges on the accurate quantification of coronary calcification. The creation of fully automated methods is ideal as complete manual evaluation is imprecise, operator dependent, time consuming and thus costly. The technical challenges posed by LDCT scans in this context are mainly twofold. First, there is a high level image noise arising from the low radiation dose technique. Additionally, there is a variable amount of cardiac motion blurring due to the lack of electrocardiographic gating and the fact that heart rates differ between human subjects. As a consequence, the reliable segmentation of the heart, the first stage toward the implementation of morphologic heart abnormality detection, is also quite challenging. An automated computer method based on a sequential labeling of major organs and determination of anatomical landmarks has been evaluated on a public database of LDCT images. The novel algorithm builds from a robust segmentation of the bones and airways and embodies a stepwise refinement starting at the top of the lungs where image noise is at its lowest and where the carina provides a good calibration landmark. The segmentation is completed at the inferior wall of the heart where extensive image noise is accommodated. This method is based on the geometry of human anatomy and does not involve training through manual markings. Using visual inspection by an expert reader as a gold standard, the algorithm achieved successful heart and major vessel segmentation in 42 of 45 low-dose CT images. In the 3 remaining cases, the cardiac base was over segmented due to incorrect hemidiaphragm localization.

  7. A reappraisal of adult thoracic and abdominal surface anatomy via CT scan in Chinese population.

    PubMed

    Shen, Xin-Hua; Su, Bai-Yan; Liu, Jing-Juan; Zhang, Gu-Muyang; Xue, Hua-Dan; Jin, Zheng-Yu; Mirjalili, S Ali; Ma, Chao

    2016-03-01

    Accurate surface anatomy is essential for safe clinical practice. There are numerous inconsistencies in clinically important surface markings among and within contemporary anatomical reference texts. The aim of this study was to investigate key thoracic and abdominal surface anatomy landmarks in living Chinese adults using computed tomography (CT). A total of 100 thoracic and 100 abdominal CT scans were examined. Our results indicated that the following key surface landmarks differed from current commonly-accepted descriptions: the positions of the tracheal bifurcation, azygos vein termination, and pulmonary trunk bifurcation (all below the plane of the sternal angle at vertebral level T5-T6 in most individuals); the superior vena cava formation and junction with the right atrium (most often behind the 1st and 4th intercostal spaces, respectively); and the level at which the inferior vena cava and esophagus traverse the diaphragm (T10 and T11, respectively). The renal arteries were most commonly at L1; the midpoint of the renal hila was most frequently at L2; the 11th rib was posterior to the left kidney in only 29% of scans; and the spleen was most frequently located between the 10th and 12th ribs. A number of significant sex- and age-related differences were noted. The Chinese population was also compared with western populations on the basis of published reports. Reappraisal of surface anatomy using modern imaging tools in vivo will provide both quantitative and qualitative evidence to facilitate the clinical application of these key surface landmarks. Clin. Anat. 29:165-174, 2016. © 2015 Wiley Periodicals, Inc. PMID:26032163

  8. Methodologies for Development of Patient Specific Bone Models from Human Body CT Scans

    NASA Astrophysics Data System (ADS)

    Chougule, Vikas Narayan; Mulay, Arati Vinayak; Ahuja, Bharatkumar Bhagatraj

    2016-06-01

    This work deals with development of algorithm for physical replication of patient specific human bone and construction of corresponding implants/inserts RP models by using Reverse Engineering approach from non-invasive medical images for surgical purpose. In medical field, the volumetric data i.e. voxel and triangular facet based models are primarily used for bio-modelling and visualization, which requires huge memory space. On the other side, recent advances in Computer Aided Design (CAD) technology provides additional facilities/functions for design, prototyping and manufacturing of any object having freeform surfaces based on boundary representation techniques. This work presents a process to physical replication of 3D rapid prototyping (RP) physical models of human bone from various CAD modeling techniques developed by using 3D point cloud data which is obtained from non-invasive CT/MRI scans in DICOM 3.0 format. This point cloud data is used for construction of 3D CAD model by fitting B-spline curves through these points and then fitting surface between these curve networks by using swept blend techniques. This process also can be achieved by generating the triangular mesh directly from 3D point cloud data without developing any surface model using any commercial CAD software. The generated STL file from 3D point cloud data is used as a basic input for RP process. The Delaunay tetrahedralization approach is used to process the 3D point cloud data to obtain STL file. CT scan data of Metacarpus (human bone) is used as the case study for the generation of the 3D RP model. A 3D physical model of the human bone is generated on rapid prototyping machine and its virtual reality model is presented for visualization. The generated CAD model by different techniques is compared for the accuracy and reliability. The results of this research work are assessed for clinical reliability in replication of human bone in medical field.

  9. Fully automated shape model positioning for bone segmentation in whole-body CT scans

    NASA Astrophysics Data System (ADS)

    Fränzle, A.; Sumkauskaite, M.; Hillengass, J.; Bäuerle, T.; Bendl, R.

    2014-03-01

    Analysing osteolytic and osteoblastic bone lesions in systematically affected skeletons, e.g. in multiple myeloma or bone metastasis, is a complex task. Quantification of the degree of bone destruction needs segmentation of all lesions but cannot be managed manually. Automatic bone lesion detection is necessary. Our future objective is comparing modified bones with healthy shape models. For applying model based strategies successfully, identification and position information of single bones is necessary. A solution to these requirements based on bone medullary cavities is presented in this paper. Medullary cavities are useful for shape model positioning since they have similar position and orientation as the bone itself but can be separated more easily. Skeleton segmentation is done by simple thresholding. Inside the skeleton medullary cavities are segmented by a flood filling algorithm. The filled regions are considered as medullary cavity objects. To provide automatic shape model selection, medullary cavity objects are assigned to bone structures with pattern recognition. To get a good starting position for shape models, principal component analysis of medullary cavities is performed. Bone identification was tested on 14 whole-body low-dose CT scans of multiple myeloma patients. Random forest classification assigns medullary cavities of long bones to the corresponding bone (overall accuracy 90%). Centroid and first principal component of medullary cavity are sufficiently similar to those of bone (mean centroid difference 21.7 mm, mean difference angle 1.54° for all long bones of one example patient) and therefore suitable for shape model initialization. This method enables locating long bone structures in whole-body CT scans and provides useful information for a reasonable shape model initialization.

  10. Distant metastases in a young woman with Stewart-Treves syndrome demonstrated by an FDG-PET/CT scan.

    PubMed

    Chen, Yu-Ren; Hsieh, Te-Chun; Yen, Kuo-Yang; Kao, Chia-Hung

    2014-11-01

    This 17-year-old woman had chronic congenital lymphedema in the left lower extremity since childhood. She underwent surgeries to remove excessive lymphedematous tissues more than 15 times previously. Histopathology of the specimen from the recent surgery revealed angiosarcoma; therefore, FDG-PET/CT scan was arranged to determine the extent of tumor spread, and distant metastases were discovered. Stewart-Treves syndrome is angiosarcomas that arise secondary to chronic lymphedema. Because of the high lethality of this condition, the FDG-PET/CT scan may be a clinically useful imaging modality to detect the possible malignant transformation earlier for patients with chronic lymphedema. PMID:24561687

  11. Longitudinal dose distribution and energy absorption in PMMA and water cylinders undergoing CT scans

    SciTech Connect

    Li, Xinhua; Zhang, Da; Liu, Bob

    2014-10-15

    Purpose: The knowledge of longitudinal dose distribution provides the most direct view of the accumulated dose in computed tomography (CT) scanning. The purpose of this work was to perform a comprehensive study of dose distribution width and energy absorption with a wide range of subject sizes and beam irradiated lengths. Methods: Cumulative dose distribution along the z-axis was calculated based on the previously published CT dose equilibration data by Li, Zhang, and Liu [Med. Phys. 40, 031903 (10pp.) (2013)] and a mechanism for computing dose on axial lines by Li, Zhang, and Liu [Med. Phys. 39, 5347–5352 (2012)]. Full width at half maximum (FWHM), full width at tenth maximum (FWTM), the total energy (E) absorbed in a small cylinder of unit mass per centimeter square about the central or peripheral axis, and the energy (E{sub in}) absorbed inside irradiated length (L) were subsequently extracted from the dose distribution. Results: Extensive results of FWHM, FWTM, and E{sub in}/E were presented on the central and peripheral axes of infinitely long PMMA (diameters 6–50 cm) and water (diameters 6–55 cm) cylinders with L < 100 cm. FWHM was greater than the primary beam width only on the central axes of large phantoms and also with L ranging from a few centimeter to about 33 cm. FWTM generally increased with phantom diameter, and could be up to 32 cm longer than irradiated length, depending on L, phantom diameter and axis, but was insensitive to phantom material (PMMA or water). E{sub in}/E increased with L and asymptotically approached unity for large L. As phantom diameter increased, E{sub in}/E generally decreased, but asymptotically approached constant levels on the peripheral axes of large phantoms. A heuristic explanation of dose distribution width results was presented. Conclusions: This study enables the reader to gain a comprehensive view of dose distribution width and energy absorption and provides useful data for estimating doses to organs inside or

  12. Conversion of a Micro-CT Scanned Rock Fracture Into a Useful Model

    SciTech Connect

    Crandall, Dustin; Bromhal, Grant; Smith, Duane

    2009-01-01

    Within geologic reservoirs the flow of fluids through fractures is often orders of magnitude greater than through the surrounding, low-permeability rock. Because of the number and size of fractures in geological fields, reservoir-scale discrete-fracture simulators often model fluid motion through fractures as flow through narrow, parallel plates. In reality fractures within rock are narrow openings between two rough rock surfaces. In order to model the geometry of an actual fracture in rock, a ~9 cm by 2.5 cm fracture within Berea sandstone was created and the aperture distribution was obtained with micro-Computed Tomography (CT) scans by Karpyn et al. [1]. The original scans had a volume-pixel (voxel) resolution of 27 by 27 by 32 microns. This data was up-scaled to voxels with 120 microns to a side to facilitate data transfer and for practicality of use. Using three separate reconstruction techniques, six different fracture meshes were created from this up-scaled data set, each with slightly different final geometries. Flow through each of these fracture meshes was evaluated using the finite-volume simulator FLUENT. While certain features of the fracture meshes, such as the shape of the fracture aperture distributions and overall volume of the void, remained similar between the different geometric reconstructions, the flow in different models was observed to vary dramatically. Rough fracture walls induced more tortuous flow paths and a higher resistance to flow. Natural fractures do vary in-situ, due to sidewall dissolution and mineral precipitation, smoothing and coarsening fracture walls respectively. Thus for our study the range of fracture properties was actually beneficial, allowing us to describe the flow through a range of fracture types. A compromise between capturing the geometric details within a domain of interest and a tractable computational mesh must always be addressed when flow through a physical geometry is modeled. The fine level of detail that

  13. Performance tests for ray-scan 64 PET/CT based on NEMA NU-2 2007

    NASA Astrophysics Data System (ADS)

    Li, Suying; Zhou, Kun; Zhang, Qiushi; Zhang, Jinming; Yang, Kun; Xu, Baixuan; Ren, Qiushi

    2015-03-01

    This paper focuses on evaluating the performance of the Ray-Scan 64 PET/CT system, a newly developed PET/CT in China. It combines a 64 slice helical CT scanner with a high resolution PET scanner based on BGO crystals assembled in 36 rings. The energy window is 350~ 650 keV, and the coincidence window is set at 12 ns in both 2D and 3D mode. The transaxial field of view (FOV) is 600 mm in diameter, and the axial FOV is 163 mm. Method: Performance measurements were conducted focusing on PET scanners based on NEMA NU-2 2007 standard. We reported the full characterization (spatial resolution, sensitivity, count rate performance, scatter fraction, accuracy of correction, and image quality) in both 2D and 3D mode. In addition, the clinical images from two patients of different types of tumor were presented to further demonstrate this PET/CT system performance in clinical application. Results: using the NEMA NU-2 2007 standard, the main results: (1) the transaxial resolution at 1cm from the gantry center for 2D and 3D was both 4.5mm (FWHM), and at 10cm from the gantry center, the radial (tangential) resolution were 5.6mm (5.3mm) and 5.4mm (5.2mm) in 2D and 3D mode respectively. The axial resolution at 1cm and 10cm off axis was 3.4mm (4.8mm) and 5.5mm (5.8mm) in 2D (3D) mode respectively; (2) the sensitivity for the radial position R0(r=0mm) and R100(r=100mm) were 1.741 kcps/MBq and 1.767 kcps/MBq respectively in 2D mode and 7.157 kcps/MBq and 7.513 kcps/MBq in 3D mode; (3) the scatter fraction was calculated as 18.36% and 42.92% in 2D and 3D mode, respectively; (4) contrast of hot spheres in the image quality phantom in 2D mode was 50.33% (52.87%), 33.34% (40.86%), 20.64% (26.36%), and 10.99% (15.82%), respectively, in N=4 (N=8). Besides, in clinical study, the diameter of lymph tumor was about 2.4 cm, and the diameter of lung cancer was 4.2 cm. This PET/CT system can distinguish the position of cancer easily. Conclusion: The results show that the performance of the newly

  14. Are routine preoperative CT scans necessary in adult cochlear implantation? Implications for the allocation of resources in cochlear implant programs.

    PubMed

    Kenway, Bruno; Vlastarakos, Petros V; Kasbekar, Anand V; Axon, Patrick R; Donnelly, Neil

    2016-08-01

    Our aim was to critically assess the influence of preoperative computed tomography (CT) scans on implantation decisions for adult cochlear implant candidates. The working hypothesis was that these routine scans might not provide critical additional information in most adult cochlear implant candidates. The charts of 175 adults with unilateral cochlear implantation were reviewed. Preoperative CT scan reports were audited, and scans with reported pathology were examined by an Otologist/ENT Surgeon. Clinic notes and multidisciplinary team meeting summaries were also analyzed to assess whether the results of the radiology report had influenced the decision to implant or the laterality of implantation. Twenty-five of the 175 scans (14.3%) showed an abnormality. Five of those 25 scans showed evidence of previous surgeries already known to the clinicians. Of the remaining 20 scans, 17 showed abnormalities, including wide vestibular aqueducts, Mondini deformities, and varying degrees of otospongiosis, the identification of which can be considered preoperatively helpful. Of the 175 scans, 3 (1.7%) demonstrated abnormalities that influenced the side of implantation or the decision to implant and, therefore, had an impact on treatment. We conclude that a preoperative CT scan seems to have an impact on treatment in only a small percentage of adult cochlear implantees. Hence, it may only need to be performed in patients with a history or clinical suspicion of meningitis or otosclerosis, if the individual was born deaf or became deaf before the age of 16, or if there are other clinical reasons to scan (e.g., otoscopic appearance). The related resources can be allocated to other facets of cochlear implant programs. PMID:27551842

  15. Importance of CT Scan of Paranasal Sinuses in the Evaluation of the Anatomical Findings in Patients Suffering from Sinonasal Polyposis.

    PubMed

    Varshney, Himanshu; Varshney, Jitendra; Biswas, Subhradev; Ghosh, S K

    2016-06-01

    Sinonasal polyps are benign lesions arising from nose and/or sinuses mucosa. Paranasal sinuses computed tomogram (CT) scan are important for functional endoscopic sinus surgery (FESS) as their information assist the surgeon in pre-operative planning. This study aimed to show importance of CT scan in evaluation of anatomical variations to prove a correlation with disease process and extent of disease in sinonasal polyposis patients. A study was done from Sept, 2010 to Sept, 2011 with 33 patients presenting with nasal polyps. All recruited patients, after thorough history, general examination and thorough ENT examination, were examined by nasal endoscopy and sinus CT scans. All scans were carried out using a 3 mm thickness in axial and coronal planes with sagittal reconstruction. An analysis was then carried out to see anatomical variations and disease extent in CT scans. Maxillary sinus was the most commonly and most severely affected sinus, while the sphenoid sinus was the least involved sinus. Ostiomeatal complex (OMC) was found to be blocked in 84.85 % cases. There were few anatomic variations (57.58 %) found as hypertrophied uncinate process (30.30 %), septal deviation (21.21 %), skull base type-2, Concha bullosa, Haller's cell, Paradoxical middle turbinate, Onodi cell, pneumatized crista galli and dehiscent skull base. Hyperdense and heterogeneous opacification in paranasal sinuses was seen in 12.12 % patients. Importance of CT scans is to know anatomical variations as etiology, fungal etiology, to know extent of polyposis and anatomical variations to prevent complications during FESS and Navigation sinus surgery. PMID:27340631

  16. How to Avoid Nontherapeutic Laparotomy in Patients With Multiple Organ Failure of Unknown Origin. The Role of CT Scan Revisited

    PubMed Central

    Fui, Stephanie Li Sun; Lupinacci, Renato Micelli; Trésallet, Christophe; Faron, Matthieu; Godiris-Petit, Gaelle; Salepcioglu, Harika; Noullet, Severine; Menegaux, Fabrice

    2015-01-01

    Diagnosis of intra-abdominal diseases in critically ill patients remains a clinical challenge. Physical examination is unreliable whereas exploratory laparotomy may aggravate patient's condition and delay further evaluation. Only a few studies have investigated the place of computed tomography (CT) on this hazardous situation. We aimed to evaluate the ability of CT to prevent unnecessary laparotomy during the management of critically ill patients. Charts of all consecutive patients who had undergone an emergency nontherapeutic laparotomy from 1996 to 2013 were retrospectively studied and patient's demographic, clinical characteristics, and surgical findings were collected. During this period 59 patients had an unnecessary laparotomy. Fifty-one patients had at least one preoperative imaging and 36 had a CT scan. CT scans were interpreted to be normal (n = 12), with minor anomalies (n = 10), or major anomalies (pneumoperitoneum, portal venous gas/pneumatosis intestinalis, thickened gallbladder wall, and small bowel obstruction signs). Surgical exploration was performed through laparotomy (n = 55) or laparoscopy. Overall mortality was 37% with a median survival after surgery of 7 days. In univariate analysis, hospitalization in ICU before surgical exploration was the only factor related to death. In our series CT scans, objectively interpreted, helped avoid unnecessary surgical exploration in 61% of our patients. PMID:25785329

  17. How to Avoid Nontherapeutic Laparotomy in Patients With Multiple Organ Failure of Unknown Origin. The Role of CT Scan Revisited.

    PubMed

    Fui, Stephanie Li Sun; Lupinacci, Renato Micelli; Trésallet, Christophe; Faron, Matthieu; Godiris-Petit, Gaelle; Salepcioglu, Harika; Noullet, Severine; Menegaux, Fabrice

    2015-03-01

    Diagnosis of intra-abdominal diseases in critically ill patients remains a clinical challenge. Physical examination is unreliable whereas exploratory laparotomy may aggravate patient's condition and delay further evaluation. Only a few studies have investigated the place of computed tomography (CT) on this hazardous situation. We aimed to evaluate the ability of CT to prevent unnecessary laparotomy during the management of critically ill patients. Charts of all consecutive patients who had undergone an emergency nontherapeutic laparotomy from 1996 to 2013 were retrospectively studied and patient's demographic, clinical characteristics, and surgical findings were collected. During this period 59 patients had an unnecessary laparotomy. Fifty-one patients had at least one preoperative imaging and 36 had a CT scan. CT scans were interpreted to be normal (n = 12), with minor anomalies (n = 10), or major anomalies (pneumoperitoneum, portal venous gas/pneumatosis intestinalis, thickened gallbladder wall, and small bowel obstruction signs). Surgical exploration was performed through laparotomy (n = 55) or laparoscopy. Overall mortality was 37% with a median survival after surgery of 7 days. In univariate analysis, hospitalization in ICU before surgical exploration was the only factor related to death. In our series CT scans, objectively interpreted, helped avoid unnecessary surgical exploration in 61% of our patients. PMID:25785329

  18. Partial scan artifact reduction (PSAR) for the assessment of cardiac perfusion in dynamic phase-correlated CT

    SciTech Connect

    Stenner, Philip; Schmidt, Bernhard; Bruder, Herbert; Allmendinger, Thomas; Haberland, Ulrike; Flohr, Thomas; Kachelriess, Marc

    2009-12-15

    Purpose: Cardiac CT achieves its high temporal resolution by lowering the scan range from 2{pi} to {pi} plus fan angle (partial scan). This, however, introduces CT-value variations, depending on the angular position of the {pi} range. These partial scan artifacts are of the order of a few HU and prevent the quantitative evaluation of perfusion measurements. The authors present the new algorithm partial scan artifact reduction (PSAR) that corrects a dynamic phase-correlated scan without a priori information. Methods: In general, a full scan does not suffer from partial scan artifacts since all projections in [0, 2{pi}] contribute to the data. To maintain the optimum temporal resolution and the phase correlation, PSAR creates an artificial full scan p{sub n}{sup AF} by projectionwise averaging a set of neighboring partial scans p{sub n}{sup P} from the same perfusion examination (typically N{approx_equal}30 phase-correlated partial scans distributed over 20 s and n=1,...,N). Corresponding to the angular range of each partial scan, the authors extract virtual partial scans p{sub n}{sup V} from the artificial full scan p{sub n}{sup AF}. A standard reconstruction yields the corresponding images f{sub n}{sup P}, f{sub n}{sup AF}, and f{sub n}{sup V}. Subtracting the virtual partial scan image f{sub n}{sup V} from the artificial full scan image f{sub n}{sup AF} yields an artifact image that can be used to correct the original partial scan image: f{sub n}{sup C}=f{sub n}{sup P}-f{sub n}{sup V}+f{sub n}{sup AF}, where f{sub n}{sup C} is the corrected image. Results: The authors evaluated the effects of scattered radiation on the partial scan artifacts using simulated and measured water phantoms and found a strong correlation. The PSAR algorithm has been validated with a simulated semianthropomorphic heart phantom and with measurements of a dynamic biological perfusion phantom. For the stationary phantoms, real full scans have been performed to provide theoretical reference

  19. Prevalence and Morphologic Features of Ponticulus Posticus in Koreans: Analysis of 312 Radiographs and 225 Three-dimensional CT Scans

    PubMed Central

    Kim, Kyeong Hwan; Park, Kun Woo; Manh, Tran Hoang; Chang, Bong-Soon; Lee, Choon-Ki

    2007-01-01

    Study Design A retrospective review of three-dimensional CT scan images and radiographs. Purpose To investigate the prevalence and morphologic features of ponticulus posticus in Koreans. Overview of Literature There has been little reported on the prevalence or morphologic characteristics of ponticulus posticus in Asians, predisposing them to vertebral artery injury during screw placement in the lateral mass of the atlas. Methods The presence and types of ponticulus posticus were investigated on 225 consecutive cervical three-dimensional CT scans and 312 consecutive digital lateral cephalometric head radiographs. Results Various spectra of ponticulus posticus were found in 26% of the CT scans and 14% of the radiographs. Conclusions Ponticulus posticus is a relatively common anomaly in Koreans. Therefore, the presence of this anomaly should be carefully examined for on radiographs before lateral mass screw placement. If ponticulus posticus is suspected or confirmed on radiographs, three-dimensional CT scanning should be considered before placement of lateral mass screws into the posterior arch, especially given its wide variation of size and shape. PMID:20411149

  20. Incorporating Radiology into Medical Gross Anatomy: Does the Use of Cadaver CT Scans Improve Students' Academic Performance in Anatomy?

    ERIC Educational Resources Information Center

    Lufler, Rebecca S.; Zumwalt, Ann C.; Romney, Carla A.; Hoagland, Todd M.

    2010-01-01

    Radiological images show anatomical structures in multiple planes and may be effective for teaching anatomical spatial relationships, something that students often find difficult to master. This study tests the hypotheses that (1) the use of cadaveric computed tomography (CT) scans in the anatomy laboratory is positively associated with…

  1. Is it possible to limit the use of CT scanning in acute diverticular disease without compromising outcomes? A preliminary experience.

    PubMed

    Caputo, Pierpaolo; Rovagnati, Marco; Carzaniga, Pier Luigi

    2015-01-01

    The aim of our study was to determine whether the use of CT scanning in the assessment of acute diverticulitis can be reduced without a negative effect on outcome. Our series consisted of 93 out of 100 patients with acute diverticulitis admitted to the Emergency Room of our institution in the period from February 2012 to March 2013.The Hinchey classification system was used to stage disease based on findings on ultrasound (US) examination and/or computed tomography (CT) scanning. We compared the patients' Hinchey stage (HS) on admission and 72 hours later. Types of treatment were defined as emergency or delayed intervention (operative approaches (OA); ultrasound-guided percutaneous drainage (UPD), and surgery. The borderline between conservative and surgical management was identified. In patients with a HS CT scans. The skill of the individual operator in US examination was found to be of key importance. As regards CT scanning, we found, in agreement with the literature, that it has greater specificity and sensitivity than US, and is therefore indicated if the patient's condition has deteriorated. PMID:25816854

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

    PubMed Central

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

    2012-01-01

    Summary Background Although CT scans are very useful clinically, potential cancer risks exist from associated ionising radiation, in particular for children who are more radiosensitive than adults. We aimed to assess the excess risk of leukaemia and brain tumours after CT scans in a cohort of children and young adults. Methods In our retrospective cohort study, we included patients without previous cancer diagnoses who were first examined with CT in National Health Service (NHS) centres in England, Wales, or Scotland (Great Britain) between 1985 and 2002, when they were younger than 22 years of age. We obtained data for cancer incidence, mortality, and loss to follow-up from the NHS Central Registry from Jan 1, 1985, to Dec 31, 2008. We estimated absorbed brain and red bone marrow doses per CT scan in mGy and assessed excess incidence of leukaemia and brain tumours cancer with Poisson relative risk models. To avoid inclusion of CT scans related to cancer diagnosis, follow-up for leukaemia began 2 years after the first CT and for brain tumours 5 years after the first CT. Findings During follow-up, 74 of 178 604 patients were diagnosed with leukaemia and 135 of 176 587 patients were diagnosed with brain tumours. We noted a positive association between radiation dose from CT scans and leukaemia (excess relative risk [ERR] per mGy 0·036, 95% CI 0·005–0·120; p=0·0097) and brain tumours (0·023, 0·010–0·049; p<0·0001). Compared with patients who received a dose of less than 5 mGy, the relative risk of leukaemia for patients who received a cumulative dose of at least 30 mGy (mean dose 51·13 mGy) was 3·18 (95% CI 1·46–6·94) and the relative risk of brain cancer for patients who received a cumulative dose of 50–74 mGy (mean dose 60·42 mGy) was 2·82 (1·33–6·03). Interpretation Use of CT scans in children to deliver cumulative doses of about 50 mGy might almost triple the risk of leukaemia and doses of about 60 mGy might triple the risk of brain

  3. Optimal cutoff threshold for calcium quantification in isotropic CT calcium scans by validating against registered intravascular ultrasound with radiofrequency backscatter.

    PubMed

    Dhungel, Abinashi; Qian, Zhen; Vazquez, Gustavo; Rinehart, Sarah; Weeks, Michael; Voros, Szilard

    2012-01-01

    3D Computed Tomography (CT) provides noninvasive, low-radiation method of coronary artery calcium (CAC) measurement. Conventional CAC images are acquired on multidetector-row CT scanners without contrast, and reconstructed with 3 mm slice thickness. The calcium volume is quantified by registering voxels with attenuation values greater than or equal to 130 Hounsfield Unit (HU). In isotropic CAC images with 0.5 mm slice thickness obtained from 320-detector row CT, the optimal value of attenuation cutoff threshold is unknown. In this paper we find the optimal cutoff threshold for calcium quantification in isotropic CT calcium scans by validating against registered intravascular ultrasound with radiofrequency backscatter (IVUS/VH). From the statistical analysis of calcium data obtained from the images of 9 patients we found a range of optimal thresholds and the conventional threshold of 130 HU was in the range. Further, the optimal values were different for individual patients. PMID:23367046

  4. Lung texture in serial thoracic CT scans: Correlation with radiologist-defined severity of acute changes following radiation therapya

    PubMed Central

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

    2014-01-01

    This study examines the correlation between the radiologist-defined severity of normal tissue damage following radiation therapy (RT) for lung cancer treatment and a set of mathematical descriptors of computed tomography (CT) scan texture (“texture features”). A pre-therapy CT scan and a post-therapy (median: 33 days) CT scan were retrospectively collected under IRB approval for each of 25 patients who underwent definitive RT (median dose: 66 Gy). Sixty regions of interest (ROIs) were automatically identified in the non-cancerous lung tissue of each post-therapy scan. A radiologist compared post-therapy scan ROIs with pre-therapy scans and categorized each as containing no abnormality, mild abnormality, moderate abnormality, or severe abnormality. Twenty texture features that characterize gray-level intensity, region morphology, and gray-level distribution were calculated in post-therapy scan ROIs and compared with anatomically matched ROIs in the pre-therapy scan. Linear regression and receiver operating characteristic (ROC) analysis were used to compare the percent feature value change (ΔFV) between ROIs at each category of visible radiation damage. Most ROIs contained no (65%) or mild abnormality (30%). ROIs with moderate (3%) or severe (2%) abnormalities were observed in 9 patients. For 19 of 20 features, ΔFV was significantly different among severity levels. For 12 features, significant differences were observed at every level. Compared with regions with no abnormalities, ΔFV for these 12 features increased, on average, by 1.5%, 12%, and 30%, respectively, for mild, moderate, and severe abnormalitites. Area under the ROC curve was largest when comparing ΔFV in the highest severity level with the remaining three categories (mean AUC across features: 0.84). In conclusion, 19 features that characterized the severity of radiologic changes from pre-therapy scans were identified. These features may be used in future studies to quantify acute normal lung

  5. Reducing false positives of small bowel segmentation on CT scans by localizing colon regions

    NASA Astrophysics Data System (ADS)

    Zhang, Weidong; Liu, Jiamin; Yao, Jianhua; Summers, Ronald M.

    2014-03-01

    Automated small bowel segmentation is essential for computer-aided diagnosis (CAD) of small bowel pathology, such as tumor detection and pre-operative planning. We previously proposed a method to segment the small bowel using the mesenteric vasculature as a roadmap. The method performed well on small bowel segmentation but produced many false positives, most of which were located on the colon. To improve the accuracy of small bowel segmentation, we propose a semi-automated method with minimum interaction to distinguish the colon from the small bowel. The method utilizes anatomic knowledge about the mesenteric vasculature and a statistical method of colon detection. First, anatomic labeling of the mesenteric arteries is used to identify the arteries supplying the colon. Second, a statistical detector is created by combining two colon probability maps. One probability map is of the colon location and is generated from colon centerlines generated from CT colonography (CTC) data. Another probability map is of 3D colon texture using Haralick features and support vector machine (SVM) classifiers. The two probability maps are combined to localize colon regions, i.e., voxels having high probabilities on both maps were labeled as colon. Third, colon regions identified by anatomical labeling and the statistical detector are removed from the original results of small bowel segmentation. The method was evaluated on 11 abdominal CT scans of patients suspected of having carcinoid tumors. The reference standard consisted of manually-labeled small bowel segmentation. The method reduced the voxel-based false positive rate of small bowel segmentation from 19.7%±3.9% to 5.9%±2.3%, with two-tailed P-value < 0.0001.

  6. Evaluation of patello-femoral alignment by CT scans: interobserver reliability of several parameters.

    PubMed

    Dei Giudici, Luca; Enea, Davide; Pierdicca, Laura; Cecconi, Stefano; Ulisse, Serena; Arima, Serena; Giovagnoni, Andrea; Gigante, Antonio

    2015-11-01

    Patello-femoral malalignment (PFM) is a common cause of disability often related to patello-femoral syndrome (PFS). Several causes have been taken into account; a proper diagnosis requires instrumental imaging and a methodical evaluation of different parameters. The aim of the present study was to identify the most reliable parameters for measuring patello-femoral and inferior limb alignment by CT. Twenty randomly selected patients suffering from PFS for a total of 40 knees were studied by static CT scans in order to assess patellar tilt, patellar displacement, patellar and trochlear morphology and inferior limb alignment. All known parameters were measured; the variability of the measurements between observers was evaluated by boxplots, Pearson's correlation coefficients, and infraclass correlation coefficient [ICC(2,1)] based on a two-way random effect model. Bland-Altman mean differences and 95 % limits of agreement were computed for each pair of measurements. Patellar tilt parameters appeared equally reliable; patellar displacement is best measured with BoTot that showed an ICC of 0.889; morphology is best measured with WibergTot, with an ICC of 0.862; lastly, for the inferior limb alignment parameters' analysis, FTV outperformed the others in terms of reliability. The present study allowed us to select a limited number of reliable parameters in the evaluation of patello-femoral and inferior limb alignment. The use of these parameters may also result in a more reliable comparison of studies on PFM and in a better evaluation of the treatment outcomes. PMID:25851081

  7. Effect of deformable registration on the dose calculated in radiation therapy planning CT scans of lung cancer patients

    SciTech Connect

    Cunliffe, Alexandra R.; Armato, Samuel G.; White, Bradley; Justusson, Julia; Contee, Clay; Malik, Renuka; Al-Hallaq, Hania A.

    2015-01-15

    Purpose: To characterize the effects of deformable image registration of serial computed tomography (CT) scans on the radiation dose calculated from a treatment planning scan. Methods: Eighteen patients who received curative doses (≥60 Gy, 2 Gy/fraction) of photon radiation therapy for lung cancer treatment were retrospectively identified. For each patient, a diagnostic-quality pretherapy (4–75 days) CT scan and a treatment planning scan with an associated dose map were collected. To establish correspondence between scan pairs, a researcher manually identified anatomically corresponding landmark point pairs between the two scans. Pretherapy scans then were coregistered with planning scans (and associated dose maps) using the demons deformable registration algorithm and two variants of the Fraunhofer MEVIS algorithm (“Fast” and “EMPIRE10”). Landmark points in each pretherapy scan were automatically mapped to the planning scan using the displacement vector field output from each of the three algorithms. The Euclidean distance between manually and automatically mapped landmark points (d{sub E}) and the absolute difference in planned dose (|ΔD|) were calculated. Using regression modeling, |ΔD| was modeled as a function of d{sub E}, dose (D), dose standard deviation (SD{sub dose}) in an eight-pixel neighborhood, and the registration algorithm used. Results: Over 1400 landmark point pairs were identified, with 58–93 (median: 84) points identified per patient. Average |ΔD| across patients was 3.5 Gy (range: 0.9–10.6 Gy). Registration accuracy was highest using the Fraunhofer MEVIS EMPIRE10 algorithm, with an average d{sub E} across patients of 5.2 mm (compared with >7 mm for the other two algorithms). Consequently, average |ΔD| was also lowest using the Fraunhofer MEVIS EMPIRE10 algorithm. |ΔD| increased significantly as a function of d{sub E} (0.42 Gy/mm), D (0.05 Gy/Gy), SD{sub dose} (1.4 Gy/Gy), and the algorithm used (≤1 Gy). Conclusions: An

  8. Effect of deformable registration on the dose calculated in radiation therapy planning CT scans of lung cancer patients a)

    PubMed Central

    Cunliffe, Alexandra R.; Contee, Clay; Armato, Samuel G.; White, Bradley; Justusson, Julia; Malik, Renuka; Al-Hallaq, Hania A.

    2015-01-01

    Purpose: To characterize the effects of deformable image registration of serial computed tomography (CT) scans on the radiation dose calculated from a treatment planning scan. Methods: Eighteen patients who received curative doses (≥60 Gy, 2 Gy/fraction) of photon radiation therapy for lung cancer treatment were retrospectively identified. For each patient, a diagnostic-quality pretherapy (4–75 days) CT scan and a treatment planning scan with an associated dose map were collected. To establish correspondence between scan pairs, a researcher manually identified anatomically corresponding landmark point pairs between the two scans. Pretherapy scans then were coregistered with planning scans (and associated dose maps) using the demons deformable registration algorithm and two variants of the Fraunhofer MEVIS algorithm (“Fast” and “EMPIRE10”). Landmark points in each pretherapy scan were automatically mapped to the planning scan using the displacement vector field output from each of the three algorithms. The Euclidean distance between manually and automatically mapped landmark points (dE) and the absolute difference in planned dose (|ΔD|) were calculated. Using regression modeling, |ΔD| was modeled as a function of dE, dose (D), dose standard deviation (SDdose) in an eight-pixel neighborhood, and the registration algorithm used. Results: Over 1400 landmark point pairs were identified, with 58–93 (median: 84) points identified per patient. Average |ΔD| across patients was 3.5 Gy (range: 0.9–10.6 Gy). Registration accuracy was highest using the Fraunhofer MEVIS EMPIRE10 algorithm, with an average dE across patients of 5.2 mm (compared with >7 mm for the other two algorithms). Consequently, average |ΔD| was also lowest using the Fraunhofer MEVIS EMPIRE10 algorithm. |ΔD| increased significantly as a function of dE (0.42 Gy/mm), D (0.05 Gy/Gy), SDdose (1.4 Gy/Gy), and the algorithm used (≤1 Gy). Conclusions: An average error of <4 Gy in radiation

  9. Single-scan scatter correction for cone-beam CT using a stationary beam blocker: a preliminary study

    NASA Astrophysics Data System (ADS)

    Niu, Tianye; Zhu, Lei

    2011-03-01

    The performance of cone-beam CT (CBCT) is greatly limited by scatter artifacts. The existing measurement-based methods have promising advantages as a standard scatter correction solution, except that they currently require multiple scans or moving the beam blocker during data acquisition to compensate for the missing primary data. These approaches are therefore unpractical in clinical applications. In this work, we propose a new measurement-based scatter correction method to achieve accurate reconstruction with one single scan and a stationary beam blocker, two seemingly incompatible features which enable simple and effective scatter correction without increase of scan time or patient dose. Based on CT reconstruction theory, we distribute the blocked areas over one projection where primary signals are considered to be redundant in a full scan. The CT image quality is not degraded even with primary loss. Scatter is accurately estimated by interpolation and scatter-corrected CT images are obtained using an FDK-based reconstruction. In a Monte Carlo simulation study, we first optimize the beam blocker geometry using projections on the Shepp-Logan phantom and then carry out a complete simulation of a CBCT scan on a water phantom. With the scatter-to-primary ratio around 1.0, our method reduces the CT number error from 293 to 2.9 Hounsfield unit (HU) around the phantom center. The proposed approach is further evaluated on a CBCT tabletop system. On the Catphan©600 phantom, the reconstruction error is reduced from 202 to 10 HU in the selected region of interest after the proposed correction.

  10. Lung texture in serial thoracic CT scans: Registration-based methods to compare anatomically matched regions1

    PubMed Central

    Cunliffe, Alexandra R.; Armato, Samuel G.; Fei, Xianhan M.; Tuohy, Rachel E.; Al-Hallaq, Hania A.

    2013-01-01

    Purpose: The aim of this study was to compare three demons registration-based methods to identify spatially matched regions in serial computed tomography (CT) scans for use in texture analysis. Methods: Two thoracic CT scans containing no lung abnormalities and acquired during serial examinations separated by at least one week were retrospectively collected from 27 patients. Over 1000 regions of interest (ROIs) were randomly placed in the lungs of each baseline scan. Anatomically matched ROIs in the corresponding follow-up scan were placed by mapping the baseline scan ROI center pixel to (1) the original follow-up scan, (2) the follow-up scan resampled to match the baseline scan voxel size, and (3) the follow-up scan aligned to the baseline scan through affine registration. Mappings used the vector field obtained through demons deformable registration of each follow-up scan variant to the baseline scan. 140 texture features distributed among five feature classes were calculated in all ROIs. Feature value differences between paired ROIs were evaluated using Bland-Altman 95% limits of agreement. For each feature, (1) the mean feature value change and (2) the difference between the upper and lower limits of agreement were normalized to the mean feature value to obtain, respectively, the normalized bias and normalized range of agreement (nRoA). Nonparametric tests were used to evaluate differences in normalized bias and nRoA across the three methods. Results: Because patient CT scans contained no pathology, minimal changes in feature values were expected (i.e., low nRoA and normalized bias). Seventy-five features with very large feature value variability (nRoA ≥ 100%) were excluded from further analysis. Across the remaining 65 features, significant differences in normalized bias were observed among the three methods. The lowest normalized bias (median: 0.06%) was achieved when feature values were calculated on original follow-up scans. The affine registration method