The results of our study indicate that the automated custom planning with couch motion is feasible and comparable with clinical planning in terms of dosimetric quality. The developed methodology provides a tool that is integratable with the current TPS without any additional resources. It designs script-based plans for dynamic couch motion-based dose delivery.

This feasibility study serves as an end-to-end test and is probably the first of its kind that thoroughly validates various ways to control the couch speed and its integration with patient motion during the dose delivery. Treatments utilizing dynamic couch-based dose delivery must include patient immobilization. Our study takes patient motion into account and provides gradual start and stop motions of the couch, which helps minimize the patient motion for treatments utilizing dynamic couch motion.

Abstract To evaluate the clinical feasibility and dosimetric benefits of a novel gantry‐static couch‐motion (GsCM) technique for external beam photon boost treatment of lumpectomy cavity in patients with early‐stage breast cancer in comparison to three‐dimensional conformal radiotherapy (3D‐CRT), wedge pair in supine position (WPS), and wedge pair in decubitus position (WPD) techniques. A retrospective review was conducted on breast patients (right breast, n = 10 and left breast, n = 10) who received 10 Gy boost after 50 Gy to whole breast. The treatment plans were generated using an isocentric‐based GsCM technique (a VMAT type planning approach) integrating couch rotational motion at static gantry positions. Static fields for each tangential side were merged using a Matlab® script and delivered automatically within the Varian TruebeamTM STx in Developer Mode application as a VMAT arc (wide‐angular medial and short‐angular lateral arcs). The dosimetric accuracy of the plan delivery was evaluated by ion chamber array measurements in phantom. For both right and left breast boost GsCM, 3D‐CRT, WPS, and WPD all provided an adequate coverage to PTV. GsCM significantly reduced the ipsilateral lung V30% for right side (mean, 80%) and left side (mean, 70%). Heart V5% reduced by 90% (mean) for right and 80% (mean) for left side. Ipsilateral breast V50% and mean dose were comparable for all techniques but for GsCM, V100% reduced by 50% (mean) for right and left side. The automated delivery of both arcs was under 2 min as compared to delivering individual fields (30 ± 5 min). The gamma analysis using 2 mm distance to agreement (DTA) and 2% dose difference (DD) was 98 ± 1.5% for all 20 plans. The GsCM technique facilitates coronal plane dose delivery appropriate for deep‐seated breast boost cavities, with sufficient dose conformity of target volume paired with sparing of the OARs.

IntroductionMRI T2* relaxometry protocols are often used for Liver Iron Quantification in patients with hemochromatosis. Several methods exist to semi-automatically segment parenchyma and exclude vessels for this calculation.PurposeTo determine if inclusion of multiple echoes inputs to Convolutional Neural Networks (CNN) improves automated liver and vessel segmentation in MRI T2* relaxometry protocols and to determine if the resultant segmentations agree with manual segmentations for liver iron quantification analysis.MethodsMulti echo Gradient Recalled Echo (GRE) MRI sequence for T2* relaxometry was performed for 79 exams on 31 patients with hemochromatosis for iron quantification analysis. 275 axial liver slices were manually segmented as ground truth masks. A batch normalized U-Net with variable input width to incorporate multiple echoes is used for segmentation, using DICE as the accuracy metric. ANOVA is used to evaluate significance of channel width changes in segmentation accuracy. Linear regression is used to model the relationship of channel width on segmentation accuracy. Liver segmentations are applied to relaxometry data to calculate liver T2* yielding liver iron concentration(LIC) derived from literature based calibration curves. Manual and CNN based LIC values are compared with Pearson correlation. Bland altman plots are used to visualize differences between manual and CNN based LIC values.ResultsPerformance metrics are tested on 55 hold out slices. Linear regression indicates that there is a monotonic increase of DICE with increasing channel depth (p = 0.001) with a slope of 3.61e-3. ANOVA indicates a significant increase segmentation accuracy over single channel starting at 3 channels. Incorporation of all channels results in an average DICE of 0.86, an average increase of 0.07 over single channel. The calculated LIC from CNN segmented livers agrees well with manual segmentation (R = 0.998, slope = 0.914, p«0.001), with an average absolute difference 0.27 ± 0.99 mg Fe/g or 1.34 ± 4.3%.ConclusionMore input echoes yields higher model accuracy until the noise floor. Echos beyond the first three echo times in GRE based T2* relaxometry do not contribute significant information for segmentation of liver for LIC calculation. Deep learning models with three channel width allow for generalization of model to protocols of more than three echoes, effectively a universal requirement for relaxometry. Deep learning segmentations achieve a good accuracy compared with manual segmentations with minimal preprocessing. Liver iron values calculated from hand segmented liver and Neural network segmented liver were not statistically different from each other.

The feasibility of a volumetric modulated arc therapy (VMAT) based coronal arc (cARC) technique for treating a single brain metastasis or lesion proximal to the brainstem or optic chiasm was evaluated. Coplanar (CP) and non-coplanar (NCP) treatment plans to an anthropomorphic head/neck phantom scanned head-first supine were compared to a cARC plan with the phantom rotated vertically. A set of planning target volumes (PTVs) were contoured centrally between the brainstem and optic chiasm (“Ant PTVs”) and posterior to brainstem (“Post PTVs”). Dosimetric indices such as conformity index (C.I.), gradient measure (G.M.), and dose volume histograms (DVHs) were compared for CP, NCP and cARC techniques. The TG101 guidelines for organs-at-risk (OARs), and 95% of PTV receiving at least 100% of the prescription dose (D95 = 100%) were used as plan objectives. Reductions in D50 and D30 to the brainstem of 85.1% ± 3.9% and 87.6% ± 3.2%, respectively were seen for “Post PTVs”, and 51.1% ± 17.8% and 85.6% ± 6.0% respectively for “Ant PTVs” using cARC versus CP (p ≤ 0.01). For chiasm, reductions of D50 and D30 were 61.7% ± 3.2% and 44.2% ± 8.9% for “Ant PTVs”, by 69.3% ± 8.0% and 74.3% ± 8.2% for “Post PTVs” (p ≤ 0.01). Comparing cARC to NCP led to similar dosimetric improvements. The conformity index (C.I.) was measured to be 1.101 ± 0.038, 1.088 ± 0.054, and 1.060 ± 0.040 for cARC, CP and NCP respectively (p ≤ 0.01). The overall GM in cm was 0.581 ± 0.097, 0.708 ± 0.064, and 0.476 ± 0.050 for cARC, CP and NCP respectively (p ≤ 0.01). The mean distance gradient fall-off (in cm) was 0.249 ± 0.038 (cARC), 0.749 ± 0.107 (CP), and 0.621 ± 0.068 (NCP) at the center slice in anterior-posterior direction of the target volume (p ≤ 0.01). The objective of this study is to compare the dosimetric indices of cARC with CP and NCP techniques. In conclusion, cARC can provide improved dosimetry as compared to CP and NCP for lesion proximal to the brainstem or optic chiasm.

Introduction: Centers for Disease Control and Prevention Diabetes Prevention Program recognition requires successful program completion by a cohort of at least five people with prediabetes. Such programs have generally been “in-person” and provided by a qualified coach from a recognized program. A cohort of 10 patients with prediabetes was enrolled in a physician’s office to use the cloud-based Type II Diabetes Prevention Module in an effort to achieve recognition. Module use was supported by the physician and a qualified coach. The purpose of this article is to evaluate Module performance relative to behavior stages associated with long-term behavior modification. Methods: The Module employs a web application supporting diabetes prevention education and a mobile application that is an electronic diary and virtual coach. A dashboard allows an efficient review of user performance and the ability to send users notifications of support from the user’s coach or physician. The cohort of 10 patients with prediabetes was offered Module use upon diagnosis of prediabetes. Results: All 10 patients with prediabetes offered Module use agreed participation. Six have completed educational sessions, made diary entries, and have met the 5% Centers for Disease Control and Prevention Diabetes Prevention Program weight loss target prior to 6 months of Module use. This high success rate (60%) is contrary to behavior stages often associated with long-term behavior modification. Conclusion: The strength of the physician–patient relationship appears to allow patients with prediabetes to skip or advance rapidly through behavioral stages in the process of lifestyle modification.

Contrast agents have been employed in radiography for more than 80 years and computed tomography (CT) for more than 50 years. These high atomic number agents increase photoelectric interaction thereby reducing photon intensity projected through the contrast agent containing structure to improve image contrast. A wide variety of contrast agents have been examined over the years, however, iodine and barium containing agents make up the majority of applications. Other agents may become available which may find utility due to reduced toxicity, better imaging characteristics or dose reduction. The purpose of this work is to develop a frame work to evaluate current and future CT contrast agents as they apply to CT enhancement of the head including CTA. The model used we have called the CT Contrast Agent Evaluation Model (CAEM) and allows the determination of the minimum effective concentration (MEC). The MEC is that concentration that provides a contrast-to-noise ratio (CNR) of one for a radiation dose of one centigray (cGy). The MEC can be examined as kilovoltage and filtration are varied allowing for optimized combinations. The approach taken in the model was to first compute x-ray tube spectra for the desired kilovoltage/filter combination. Next, projection data was computed through a cylindrical phantom with a central contrast containing target. Noise was applied to projection data based on photon counting. The application of filtered back projection to the noisy projection data could be used to compute a simulated image from which image CNR could be determined. This process was simplified by computing the CNR of the projection data and correcting for propagation of error using an empirically derived correction factor. The radiation exposure in air at the target can be accurately estimated from the computed x-ray spectra and used to determine dose. The computed CNR and dose were validated by direct measure using a clinical scanner.

PURPOSE The objective of this study is to verify and analyze the accuracy of a clinical deformable image registration (DIR) software. METHODS To test clinical DIR software qualitatively and quantitatively, we focused on lung radiotherapy and analyzed a single (Lung) patient CT scan. Artificial anatomical changes were applied to account for daily variations during the course of treatment including the planning target volume (PTV) and organs at risk (OAR). The primary CT (pCT) and the structure set (pST) was deformed with commercial tool (ImSimQA-Oncology Systems Limited) and after artificial deformation (dCT and dST) sent to another commercial tool (VelocityAI-Varian Medical Systems). In Velocity, the deformed CT and structures (dCT and dST) were inversely deformed back to original primary CT (dbpCT and dbpST). We compared the dbpST and pST structure sets using similarity metrics. Furthermore, a binary deformation field vector (BDF) was created and sent to ImSimQA software for comparison with known "ground truth" deformation vector fields (DVF). RESULTS An image similarity comparison was made by using "ground truth" DVF and "deformed output" BDF with an output of normalized "cross correlation (CC)" and "mutual information (MI)" in ImSimQA software. Results for the lung case were MI=0.66 and CC=0.99. The artificial structure deformation in both pST and dbpST was analyzed using DICE coefficient, mean distance to conformity (MDC) and deformation field error volume histogram (DFEVH) by comparing them before and after inverse deformation. We have noticed inadequate structure match for CTV, ITV and PTV due to close proximity of heart and overall affected by lung expansion. CONCLUSION We have seen similarity between pCT and dbpCT but not so well between pST and dbpST, because of inadequate structure deformation in clinical DIR system. This system based quality assurance test will prepare us for adopting the guidelines of upcoming AAPM task group 132 protocol.

Graphene nanoplatelets (GNPs), synthesized using potassium permanganate-based oxidation and exfoliation followed by reduction with hydroiodic acid (rGNP-HI), have intercalated manganese ions within the graphene sheets, and upon functionalization with iodine, show excellent potential as biomodal contrast agents for magnetic resonance imaging (MRI) and computed tomography (CT). Structural characterization of rGNP-HI nanoparticles with low- and high-resolution transmission electron microscope (TEM) showed disc-shaped nanoparticles (average diameter, 200 nm, average thickness, 3 nm). Energy dispersive X-ray spectroscopy (EDX) analysis confirmed the presence of intercalated manganese. Raman spectroscopy and X-ray diffraction (XRD) analysis of rGNP-HI confirmed the reduction of oxidized GNPs (O-GNPs), absence of molecular and physically adsorbed iodine, and the functionalization of graphene with iodine as polyiodide complexes (I3- and I5-). Manganese and iodine content were quantified as 5.1 ± 0.5 and 10.54 ± 0.87 wt% by inductively-coupled plasma optical emission spectroscopy and ion-selective electrode measurements, respectively. In vitro cytotoxicity analysis, using absorbance (LDH assay) and fluorescence (calcein AM) based assays, performed on NIH3T3 mouse fibroblasts and A498 human kidney epithelial cells, showed CD50 values of rGNP-HI between 179-301 µg/ml, depending on the cell line and the cytotoxicity assay. CT and MRI phantom imaging of rGNP-HI showed high CT (approximately 3200% greater than HI at equimolar iodine concentration) and MRI (approximately 59% greater than equimolar Mn2+ solution) contrast. These results open avenues for further in vivo safety and efficacy studies towards the development of carbon nanostructure-based multimodal MRI-CT contrast agents.

We report the synthesis and characterization of a novel carbon nanostructure-based magnetic resonance imaging contrast agent (MRI CA); graphene nanoplatelets intercalated with manganese (Mn2+) ions, functionalized with dextran (GNP-Dex); and the in vitro assessment of its essential preclinical physicochemical properties: osmolality, viscosity, partition coefficient, protein binding, thermostability, histamine release, and relaxivity. The results indicate that, at concentrations between 0.1 and 100.0 mg/mL, the GNP-Dex formulations are hydrophilic, highly soluble, and stable in deionized water, as well as iso-osmolar (upon addition of mannitol) and iso-viscous to blood. At potential steady-state equilibrium concentrations in blood (0.1-10.0 mg/mL), the thermostability, protein-binding, and histamine-release studies indicate that the GNP-Dex formulations are thermally stable (with no Mn2+ ion dissociation), do not allow non-specific protein adsorption, and elicit negligible allergic response. The r(1) relaxivity of GNP-Dex was 92 mM(-1)s(-1) (per-Mn2+ ion, 22 MHz proton Larmor frequency); similar to 20- to 30-fold greater than that of clinical gadolinium (Gd3+)- and Mn2+-based MRI CAs. The results open avenues for preclinical in vivo safety and efficacy studies with GNP-Dex toward its development as a clinical MRI CA.

Arguing against the Proposition is Terry M. Button, Ph.D. Dr. Button started in Medical Physics as a Masters level physicist in Radiation Safety and Radiation Oncology in the late 1970s. He obtained his Ph.D. in Biophysics from the State University of New York at Buffalo (Roswell Park) in 1989, with his research focused on magnetic resonance. Upon graduation, he worked as an Imaging Physicist at Columbia Presbyterian until he moved to Stony Brook University in 1991. He established a graduate Medical Physics Program at Stony Brook with Dr. Lawrence Reinstein in 2002, which recently obtained CAMPEP accreditation. He also established an Imaging Physics Residency Program at Stony Brook, which has been accredited since 2009. He is an Associate Professor of Radiology, Biomedical Engineering, and Health Sciences. He oversees the undergraduate Radiological Sciences Program at Stony Brook and is the Chair of the University Radiation Protection Committee (URPC). He has served the ABMP for the past decade as a member of the Board, Panel Chair for Part I and, currently, as Panel Co-Chair of the MR Examinations. He is certified by the ABR in Diagnostic Radiologic Physics and by the ABMP in Diagnostic Physics and Magnetic Resonance. Diagnostic imaging (DI) and nuclear medicine (NM) have been intertwined with medical physics dating back to the discovery of x-rays and radioactivity. As imaging technologies continue to advance and expand into new applications, they increasingly require skilled expertise to understand the delicacy of their operation, monitor their performance, design their effective use, and ensure their overall quality and safety. Even though the ACR accreditation process has highlighted the clinical role of physicists in imaging operations, that role has largely remained a severely untapped resource. Most imaging centers fail to appreciate this potential, with medical physics groups either nonexistent or highly understaffed and their services poorly integrated into the patient care process. As a field, we have yet to define how these clinical physicists can engage as active, effective, and indispensible members of the clinical team, and how the services that they provide can be financially supported. Physicists do, and always will, contribute to research and development. However, their contributions to clinical operations in DI/NM have not been adequately established. In the face of the challenge of unleashing the real potential of clinical physics in DI and NM operations, we now further face the challenge of the new ABR requirement for the completion of an accredited residency to become eligible for board certification. The basis of this requirement is a well-justified desire to enhance and standardize the clinical competencies of physicists. However, the number of accredited residencies in the US, six in DI and none in NM at the time of this writing, is well below what can be considered adequate to meet the demand. Whilst we wish to expand the role of clinical physicists in DI/NM, the enactment of the ABR requirement by 2014 would bring about a move in the opposite direction. This is because ABR-certified physicists will not be available in adequate numbers to meet the demand in DI/NM and, as a result, even the subpar role that medical physicists currently play in the clinic will be outsourced to other specialists without sufficient physics training, clinical or not. Hence, the objective of enhancing clinical skills will not be served and ABR certification will no longer be considered essential. The result will be a further weakening of the clinical role of physicists in DI/NM and a reduction in their numbers. What we are facing is no simple challenge. On the one hand, we indeed wish to enhance the standard of practice in clinical medical physics through accredited residencies. On the other hand, however, a premature mandate might actually undermine this very objective. Recognizing that physicists are skilled at finding solutions to hard problems, I believe a solution can be found if we allow our inspiring idealism to meet practical realities. An initiative is an introductory step leading to action. The 2014 initiative leads all Medical Physics clinical training program directors to act to conform to the CAMPEP approved format. The guidelines that are available to do this are clear and easy to implement.1,2 It is also essential for program directors to act now if there is hope for their candidates to sit for the Boards in 2014! The first mission of the AAPM (Ref. 3) is to promote the highest quality medical physics services for patients. From this, follows the fourth mission:3 to foster the education and professional development of medical physicists. So what is the best training available for medical physicists? An excellent indicator of performance is the “pass rate” of candidates on their Board examinations. For example, to 2005, 95% of candidates who had completed a CAMPEP accredited residency program passed the full board examination on their first attempt compared to the average pass rate of 53% over the same period.4 More recent data for the oral examination, though not quite so impressive for CAMPEP residency program graduates, still showed a significant advantage for residents: over the period 2003–2008, the oral examination pass rate for first time takers ranged from 47 to 59% while the pass rate for those from CAMPEP accredited residencies ranged from 80 to 90%!5 The primary reason for improved performance is obvious. A CAMPEP accredited residency is required to be carefully structured to cover the entire spectrum of the appropriate Medical Physics disciplines. To be accredited, the program must be complete; there can be no missing components. Unfortunately, as recently as 2008, AAPM Task Group #133 reported that more than half of all clinical medical physics training (54%) is done on the job, while only 14% of clinical training takes place in a CAMPEP-accredited residency program.2 Current Imaging Physics statistics are probably similar given that there are only six CAMPEP approved residency programs.6 The financial implementation of a residency program is challenging. Who is going to pay for this training? Program directors need to be creative to get funding for residency slots. In my program, for example, I have added a clinical affiliate and catered to the needs of my Department by planning to focus on strong MR candidates for an additional MR fellowship component. Clearly there are obstacles in the path of the goal of excellence that is the 2014 initiative but we must find solutions. Since the largest benefactors of clinical training are the candidates, the cost of this training may, in the future, increasingly be the responsibility of the candidates themselves. We physicists have generally been spoiled by the availability of graduate student support. Maybe those days are gone for medical physics. I agree with my respected colleague that, in an ideal world, completion of a residency can ensure a consistent level of competency for practicing clinical medical physicists. However, with only a handful of residencies in DI/NM, enforcement of the new eligibility requirement in less than two years from now would lead to an insufficient number of board-certified physicists, at a time when we need such individuals more than ever to support clinical practice. Hospitals need technical support to maintain image quality and manage radiation dose, but regulations do not require them to employ ABR-certified medical physicists for this purpose. An alternative workforce of engineers or specialized technologists is used around the world to answer this need. If insufficient ABR-certified physicists are available, hospital administrators will resort to the next available (and less expensive) alternative. This trend, once initiated, may become a permanent and irreversible fixture of American medicine. A critical fact is that our profession currently does not have the financial means to bring the needed number of residencies into existence. The curricular expectations of a CAMPEP-accredited program are too extensive to enable a level of clinical productivity on the part of residents sufficient to claim much compensation from clinical sources; at the same time, the responsibilities of current physicists are too extensive to allow the significant donation of time and attention needed for quality training. Meanwhile, healthcare reform intends to reduce the so-called “overuse” of expensive diagnostic imaging procedures, and to curtail associated charges and fees. Simultaneously, NIH extramural research funding is falling. Who can or will cover the burden prescribed by our professional idealism? As much as I value and support accredited residencies, enforcing a premature deadline of 2014 without strategic actions years in advance, and without considering the particularities of DI/NM physics, will not produce the desired outcome. We need to go after the crux of the problem (i.e., inadequate funding). Requirements and regulations can only do so much without addressing the fundamental limitation at hand. Since the discovery of x-rays by Roentgen, physical scientists have played an essential role in clinical Radiology and have been the backbone of growth and proliferation of new imaging technologies. While it is true that the revenue sources to support imaging medical physicists are not as clearly defined at it is for our oncology medical physics colleagues, the services required of imaging medical physicists have never been more clearly defined. Moreover, these services are mandated by virtue of the reimbursement implications of accreditation and compliance. It is true that only a handful of CAMPEP accredited Imaging Medical Physics residency programs exist. However, until now there has been little incentive to formalize existing imaging post doctoral programs to meet CAMPEP requirements. With the 2014 initiative looming, however, there is plenty of incentive! Residency program accreditation is relatively easy to obtain and having it should provide the best students available. I feel that the number of accredited programs will greatly increase over the next few years. It is important to remember that at the beginning of World War II biplanes were still in use. By the end of the war, jet planes were being placed into service. Necessity can force remarkable advances. I feel that the 2014 initiative will greatly enhance the standard of imaging medical physics practice.

PURPOSE:To develop open source software for post processing of susceptibility weighted (SWI) MR images using magnitude and phase data.METHODS:SWI data was acquired using Philips MRI 3T scanner with the following parameter: 3D T1 FFE axial with TR=40ms, TE=25ms, FOV=22 cm, acquisition matrix of 440×440 and 40 slices. Both magnitude and phase data was stored for SWI post processing. The SWI homodyne filtering is performed by converting the magnitude and phase image to complex real and imaginary images. The SWI software was implemented in C++ using ITK (Image registration and segmentation toolkit) toolkit. To generate SWI maps the user needs to provide the DICOM data directory, the series number of DICOM SWI series, low pass filter size and the weighting factor of phase mask. This outputted SWI series is saved as DICOM and appended to the patient series and can be viewed in any DICOM compatible viewer. The software also outputs SWI filtered phase maps which can be further used for iron quantification in organs like brain, liver etc.RESULTS:An open source implementation of SWI post-processing tool using ITK was provided. The SWI processed phase weighted data can be used for qualitative assessment of iron deposits. The filtered phase map outputted can be used for quantitative iron measurements.CONCLUSIONS:SWI post processing software is implemented here to provide qualitative SWI maps of iron deposits in brain and other organs. The post processed images can also be useful for MR Venography with minimum intensity projection. This tool would be useful to study disease processes involved with accumulation of iron in different organs.

Purpose: A model is presented that has been designed to evaluate and optimize the use of CT based contrast agents. Initial validation of the model was undertaken and presented here. Methods: The model employs computed spectra from the x‐ray tube at a specified kilovoltage, attenuation correct ion applied to the spectra for filtration and projection of the spectra through a cylindrically symmetric phantom which may also contain a virtual contrast agent filled target at its center. Noise was applied to computed projection data based on photon counting and standard filtered back projection applied to provide a simulated image from which signal‐to‐noise (SNR) can be computed. In the case of a virtual contrast agent filled target, the contrast‐to‐noise ratio (CNR) can be determined as well. Dose at the center of the phantom is computed from the calculated photon fluence. In this model, the CNR per unit radiation dose and/or per unit of contrast agent may be computed. The impact of kilovoltage and filtration on this parameter may be assessed allowing for optimized imaging conditions. In this initial validation of the model a uniform water equivalent plastic phantom was assumed and the CT number and radiation dose were computed for a CT system operating at 120 kVp and 100 mAs. The results were compared to direct measurement for a GE CT system under these conditions.Results: The CT number and dose provided by the model was ‐ 0.04 and 0.440 cGy respectively. This agreed within 3.5 H.U. and 11% of measured value when scatter is added to the model Conclusions: Computed tomography dose, and with further refinement, SNR and CNR may be accurately computed using this model. Placing a virtual contrast agent containing target at the phantom center will allow for prototype contrast agent evaluation and allow for the optimization of technical parameters.

Purpose: To use diffusion tensor imaging (DTI) to visualize and evaluate normal fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the sciatic nerve in four volunteers at 3T.Methods: Initially, T1‐ weighted axial anatomic reference images were performed for anatomic reference (TR/TE, 641/10; flip angle 90 degrees; field of view, 128 mm; number of signal averages(NSA) of 2. Next, single‐shot spin‐echo echo‐ planar DTI sequences were performed with parameters: TR/TE, 5300/69; flip angle 90 degrees; field of view 16 cm; matrix size 128 × 128; 2 NSA; slice thickness 4 mm; number of slices, 40. Diffusion weighting with a b value of 1,000 s/mm2 was applied in 32 different directions. Total required imaging time was approximately 15 minutes. Image data was transferred to a workstation and fiber tracking was performed with Philips advanced tractography software available on the scanner and workstation. Color coded maps demonstrating the sciatic nerve were used to place circular regions‐of interest were then drawn over the nerve location demonstrated on the color coded maps to determine FA and ADCResults: In four volunteers (all males, average age = 40) the sciatic nerve was well visualized and had an average +/− SD FA of 0.52+/−0.20and ADC of ACD of 0.78+/−0.38 Conclusions: Normal FA and ADC values of the sciatic nerve could be measured using DTI and fiber tracking. Further studies are needed but these results suggest that FA and ADC can potentially be used to evaluate peripheral neuropathy and be used in patient follow‐up.

Characterization methods for grazing-incidence reflecting channel arrays are discussed. Characterization of single-reflection, unactuated micro-structured optical arrays is required to evaluate their performance as focusing elements. Numerical simulations allow the contribution of the x-rays reflected by the channel walls to be distinguished from the overall transmitted signal, and are applied to axial sources. Experimental results are also shown to support the simulations by translation of the channel structure parallel to a detector plane, allowing separation of reflected and transmitted x-rays through the array on the detector.

Objective. The purpose of this study is to determine fetal dose during four different stages of pregnancy for both pulmonary CT angiogram and abdominal and pelvic CT examination on 4-, 16-, and 64-MDCT scanners measured in an anthropomorphic phantom simulating a pregnant patient.MATERIALS AND MET HODS. Pulmonary angiograms and abdominal and pelvic studies were performed on a phantom on 4-, 16-, and 64-MDCT scanners. Fetal positioning and mean fetal depth were determined using data from ultrasound examinations of a large cohort of patients. Scans were performed for early pregnancy and for 10, 18, and 36 weeks. Gestational age, fetal dose, and entrance skin exposure were measured.RESULTS. When constant parameters were used for pulmonary CT angiograms, the fetal radiation dose was not significantly associated with gestational age. For abdominal examinations, the 64-MDCT scanner imparted a 20% higher dose during the third trimester than did the other scanners. When scanning parameters were kept constant between machines, gestational age and fetal dose were not significantly different. However, when the manufacturer-recommended protocols for pregnant patients were used, the dose was significantly higher in the third trimester on the 64-MDCT scanner.CONCLUSION. The 64-MDCT scanner is the most dose-efficient machine when the fetus is outside the direct scan volume, as in the case of pulmonary angiograms. For abdominal examinations, the 64-MDCT scanner imparted the highest fetal dose. This finding is attributable to the increased tube current used to penetrate the larger amount of soft tissue in late pregnancy. Abdominal shielding may reduce fetal dose without affecting diagnostic ability.

Purpose: The purpose of this study was to retrospectively evaluate dynamic contrast enhanced (DCE) breast magnetic resonance imaging (MRI) data. Texture analysis is applied to extract features from this data and test the feasibility of using these texture features for creating a computer aided diagnostic system (CAD). Methods: Computation time for texture feature extraction for the entire 3D dataset precludes whole breast analysis. Reduction of data can be best accomplished through the generation of angiogenesis (parametric maps) based on contrast agent kinetics and the knowledge that malignancy exhibits rapid uptake and plateau or slow washout on the DCE curve. Breast image data that exhibits these high‐risk characteristics can be segmented into volumes‐of‐interest (VOIs). These volumes‐of‐interest can be projected on high resolution post contrast (T1) images using direction cosines information stored in the image header. The corresponding projected VOI on the high resolution, post contrast MR image can undergo feature extraction. Total 35 VOIs were extracted (16 benign + 19 malignant). In all 53 texture features such as grey level cooccurrence matrix (GLCM), second orientation pyramids (SOP), wavelets, gabor feature maps and 3 geometric features for each volume‐of‐interest was generated. Classification was performed using off the shelf classifiers and also with minimum enclosing ball (MEB) classifier designed by us. The efficacy of texture features to classify suspect VOIs as malignant or benign was evaluated.Results: Classification using the first 14 Fisher ranked coefficients using MEB classifier produces the best results with sensitivity of 88%, specificity of 83%, and accuracy of 86% Conclusions: Machine classification of breast cancer detection from DCE MRI is encouraging. Clearly additional work in this area is required. The hypothesis that feature extraction and machine learning alone has produced good sensitivity and specificity can be proven with 95% significance level only by the study of larger datasets.

Purpose: The potential application of “in beam” anterior shields were examined from fetal dose reduction and image quality perspectives.Methods: Dose reduction afforded by commercially available bismuth impregnated synthetic rubber fabricated as 12.5 and 25 cm wide anterior shields was measured. Thermoluminescent dosimeters (TLDs) irradiated in a Rando phantom were used to estimate fetal dose. Average fetal position at 0 and 18 weeks post conception were determined based on ultrasound data of fetal position by gestational age. The latter stage of pregnancy (18 weeks) was simulated by adding tissue equivalent bolus material over the anterior surface of the phantom. To assess the impact of anterior shielding on image quality, an RMI 461A body phantom with low contrast resolution phantom insert was employed. The minimum size of low contrast resolution target visualize was recorded with no shielding, 12.5 cm wide shielding and 25 cm wide shielding.Results: At 120kVp, the 12.5 cm wide bismuth impregnated synthetic rubber shield was shown to reduce fetal dose 14% and 17% at 0 and 18 weeks post conception while the 25 cm shield reduced fetal dose 22% and 38% at 0 weeks and 18 weeks post conception. These shields produce only minor artifacts and do not adversely impact low contrast resolution. It should be noted that the use of these shields in automatic tube current modulation mode may not reduce fetal dose. Conclusions: These shields may prove to be useful for clinical fetal dose reduction early in pregnancy. It should be noted that similar results may also be achieved by tube current modulation to reduce the anterior dose contribution.