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DOE OSTI2015

SU-E-T-427: Feasibility Study for Evaluation of IMRT Dose Distribution Using Geant4-Based Automated Algorithms

Purpose: For intensity-modulated radiation therapy (IMRT) treatment planning validation using Monte Carlo (MC) simulations, a precise and automated procedure is necessary to evaluate the patient dose distribution. The aim of this study is to develop an automated algorithm for IMRT simulations using DICOM files and to evaluate the patient dose based on 4D simulation using the Geant4 MC toolkit. Methods: The head of a clinical linac (Varian Clinac 2300 IX) was modeled in Geant4 along with particular components such as the flattening filter and the multi-leaf collimator (MLC). Patient information and the position of the MLC were imported from the DICOM-RT interface. For each position of the MLC, a step- and-shoot technique was adopted. PDDs and lateral profiles were simulated in a water phantom (50×50×40 cm{sup 3}) and compared to measurement data. We used a lung phantom and MC-dose calculations were compared to the clinical treatment planning used at the Seoul National University Hospital. Results: In order to reproduce the measurement data, we tuned three free parameters: mean and standard deviation of the primary electron beam energy and the beam spot size. These parameters for 6 MV were found to be 5.6 MeV, 0.2378 MeV and 1 mm FWHM respectively. The average dose difference between measurements and simulations was less than 2% for PDDs and radial profiles. The lung phantom study showed fairly good agreement between MC and planning dose despite some unavoidable statistical fluctuation. Conclusion: The current feasibility study using the lung phantom shows the potential for IMRT dose validation using 4D MC simulations using Geant4 tool kits. This research was supported by Korea Institute of Nuclear safety and Development of Measurement Standards for Medical Radiation funded by Korea research Institute of Standards and Science. (KRISS-2015-15011032)

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

SU-E-T-783: Using Matrixx to Determine Transit Dose Contribution Over Clinically Useful Limits of HDR Source Activity

Purpose: Most HDR brachytherapy treatment planning systems (TPS) use TG-43 formalism to calculate dose without including transit dose corrections. Historically, measurement of this contribution has required sophisticated apparatus unavailable in most hospitals. We use Matrixx to investigate several scenarios where transit dose contribution may effect a clinical treatment. Methods: Treatment plans were generated using Oncentra Brachy TPS (Version 4.3.0.410, Nucletron ) on a CT scan of a 24-catheter Freiburg applicator (Nucletron ) laid flat on the MatriXX (IBA) detector. This detector is an array of 1020 parallel plate ion chambers. All 24 catheters were digitized and dwells within a central square region of 5×5cm of the applicator were activated. Each of the active catheters had 6 dwells in increments of 1.0cm. The plans were normalized to 10mm. This places the 100% isodose line at the correct effective point of measurement, which lies half-way between the parallel plates of the ion chambers. It is also within the clinically relevant treatment depth for superficial applications. A total of 6 plans were delivered for 3 prescription doses, 1Gy, 2Gy and 4Gy using source activities of 2.9Ci and 11.2Ci. The MatriXX array was operated to capture dosimetric snaps every 500ms and yielded an integral dose at the end of treatment. Results: A comparison of integral dose from 2 different source activities shows that the transit dose contribution is larger when the source activity is higher. It is also observed that the relative transit dose contribution decreases as prescription dose increases. This is quantified by the Gamma analysis. Conclusion: We have demonstrated that the Matrixx detector can be used to evaluate the contribution for a HDR source during transit from the HDR afterloader to a dwell location, and between adjacent dwell locations.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

SU-F-BRA-16: Development of a Radiation Monitoring Device Using a Low-Cost CCD Camera Following Radionuclide Therapy

Purpose: It is now commonplace to handle treatments of hyperthyroidism using iodine-131 as an outpatient procedure due to lower costs and less stringent federal regulations. The Nuclear Regulatory Commission has currently updated release guidelines for these procedures, but there is still a large uncertainty in the dose to the public. Current guidelines to minimize dose to the public require patients to remain isolated after treatment. The purpose of this study was to use a low-cost common device, such as a cell phone, to estimate exposure emitted from a patient to the general public. Methods: Measurements were performed using an Apple iPhone 3GS and a Cs-137 irradiator. The charge-coupled device (CCD) camera on the phone was irradiated to exposure rates ranging from 0.1 mR/hr to 100 mR/hr and 30-sec videos were taken during irradiation with the camera lens covered by electrical tape. Interactions were detected as white pixels on a black background in each video. Both single threshold (ST) and colony counting (CC) methods were performed using MATLAB®. Calibration curves were determined by comparing the total pixel intensity output from each method to the known exposure rate. Results: The calibration curve showed a linear relationship above 5 mR/hr for both analysis techniques. The number of events counted per unit exposure rate within the linear region was 19.5 ± 0.7 events/mR and 8.9 ± 0.4 events/mR for the ST and CC methods respectively. Conclusion: Two algorithms were developed and show a linear relationship between photons detected by a CCD camera and low exposure rates, in the range of 5 mR/hr to 100-mR/hr. Future work aims to refine this model by investigating the dose-rate and energy dependencies of the camera response. This algorithm allows for quantitative monitoring of exposure from patients treated with iodine-131 using a simple device outside of the hospital.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

MO-DE-BRA-06: MrRSCAL: A Radiological Simulation Tool for Resident Education

Purpose: The goal of this project was to create a readily accessible, comprehensive-yet-flexible interactive MRI simulation tool for use in training and education of radiology residents in particular. This tool was developed to take the place of an MR scanner in laboratory activities, as magnet time has become scarce while hospitals are optimizing clinical scheduling for improved throughput. Methods: MrRSCAL (Magnetic resonance Resident Simulation Console for Active Learning) was programmed and coded using Matlab on a Mac workstation utilizing OS X platform. MR-based brain images were obtained from one of the co-authors and processed to generate parametric maps. Scanner sounds are also generated via mp3 convolution of a single MR gradient slew with a time-profile of gradient waveforms. Results: MrRSCAL facilitates the simulation of multiple MR sequences with the ability to alter MR parameters via an intuitive GUI control panel. The application allows the user to gain real-time understanding of image transformation when varying these said parameters by examining the resulting images. Lab procedures can be loaded and displayed for more directed study. The panel is also configurable, providing a simple interface for elementary labs or a full array of controls for the expert user. Conclusion: Our introduction of MrRSCAL, which is readily available to users with a current laptop or workstation, allows for individual or group study of MR image acquisition with immediate educational feedback as the MR parameters are manipulated. MrRSCAL can be used at any time and any place once installed, offering a new tool for reviewing relaxometric and artifact principles when studying for boards or investigating properties of a pulse sequence. This tool promises to be extremely useful in conveying traditionally difficult and abstract concepts involved with MR to the radiology resident and other medical professionals at large.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

MO-DE-207-04: Imaging educational program on solutions to common pediatric imaging challenges

This imaging educational program will focus on solutions to common pediatric imaging challenges. The speakers will present collective knowledge on best practices in pediatric imaging from their experience at dedicated children’s hospitals. The educational program will begin with a detailed discussion of the optimal configuration of fluoroscopes for general pediatric procedures. Following this introduction will be a focused discussion on the utility of Dual Energy CT for imaging children. The third lecture will address the substantial challenge of obtaining consistent image post -processing in pediatric digital radiography. The fourth and final lecture will address best practices in pediatric MRI including a discussion of ancillary methods to reduce sedation and anesthesia rates. Learning Objectives: To learn techniques for optimizing radiation dose and image quality in pediatric fluoroscopy To become familiar with the unique challenges and applications of Dual Energy CT in pediatric imaging To learn solutions for consistent post-processing quality in pediatric digital radiography To understand the key components of an effective MRI safety and quality program for the pediatric practice.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

TU-G-BRD-03: IMRT Dosimetry Differences in An Institution with Community and Academic Model

Purpose: Radiation outcome among institutions can be interpreted meaningfully if the dose delivery and prescription to the target volume is documented accurately and consistently. ICRU-83 recommended specific guidelines in IMRT for target volume definitions and dose reporting. This retrospective study evaluates the pattern of IMRT dose prescription and recording in an academic institution (AI) and a community hospital (CH) models in a single institution with reference to ICRU-83 recommendation. Materials & Methods: Dosimetric information of 625 (500 from academic and 125 from community) patients treated with IMRT was collected retrospectively from the AI and a CH. The dose-volume histogram (DVH) for the target volume of each patient was extracted. Standard dose parameters such as D2, D50, D95, D98, D100, as well as the homogeneity index (HI) defined as (D2-D98)/D50 and monitor units (MUs) were collected. Results: Significant dosimetric variations were observed in disease sites and between AI and CH. The variation in the mean value of D95 for AI is 98.48±4.12 and for CH is 96.41±4.13. A similar pattern was noticed for D50 (104.18±6.04 for AI and 101.05±3.49 for CH). Thus, nearly 95% of patients received dosage higher than 100% to the site viewed by D50 and varied between AI and CH models. The average variation of HI is found to be 0.12±0.08 and 0.11±0.08 for AI and CH model, showing better IMRT treatment plans for academic model compared to community. Conclusion: Even with the implementation of ICRU-83 guidelines, there is a large variation in dose prescription and delivery in IMRT. The variation is institution and site specific. For any meaningful comparison of the IMRT outcome, strict guidelines for dose reporting should be maintained in every institution.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

WE-A-207-00: In Memoriam of Jacques Ovadia - Reinvigorating Scientific Excellence: Electron Beam Therapy - Past, Present and Future

The Medical Physics community lost one of its early pioneers in radiation oncology physics, Jacques Ovadia, who passed away in April of 2014 at the age of 90. Jacques received his Ph.D. in Nuclear Physics from the University of Illinois at Urbana in 1951. Subsequently, under the guidance of John Laughlin, he was introduced to the field of Medical Physics. When John moved to Memorial Sloan Kettering, Jacques followed him. There he gained clinical experience and expertise in the then cutting-edge field of high energy electron beam therapy. In 1956, Jacques joined Dr. Erich Uhlmann at Michael Reese Hospital in Chicago where one of the country’s first high energy medical linear accelerators had just been installed. During his 35 year tenure, Dr. Ovadia built a strong Medical Physics department that merged in 1984 with that of the University of Chicago. Jacques pioneered the use of high energy electron beams to treat deep seated tumors, multiple-field chest wall irradiation with variable electron energies, and even anticipated the current interest in high energy electron beam grid-therapy. At an early stage, he introduced a simulator, computerized treatment planning and in-house developed record and verify software. He retired in 1990 as Professor emeritus in Radiation and Cellular Biology at the University of Chicago. Dr. Ovadia was an early and strong supporter of AAPM. He was present at the Chicago ROMPS meeting where the decision was made to form an independent professional society for medical physics. He served as AAPM president in 1976. Jacques Ovadia is survived by his wife of 58 years, Florence, their daughter Corinne Graefe and son Marc Ovadia, MD, as well as four grandchildren and one great-grandchild. Jacques’ dynamic and ever enthusiastic personality inspired all who collaborated with him. He will be greatly missed.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

WE-A-207-01: Memorial Lecturer

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

Technical Note: On the calculation of stopping-power ratio for stoichiometric calibration in proton therapy

Purpose: The quantitative effects of assumptions made in the calculation of stopping-power ratios (SPRs) are investigated, for stoichiometric CT calibration in proton therapy. The assumptions investigated include the use of the Bethe formula without correction terms, Bragg additivity, the choice of I-value for water, and the data source for elemental I-values. Methods: The predictions of the Bethe formula for SPR (no correction terms) were validated against more sophisticated calculations using the SRIM software package for 72 human tissues. A stoichiometric calibration was then performed at our hospital. SPR was calculated for the human tissues using either the assumption of simple Bragg additivity or the Seltzer-Berger rule (as used in ICRU Reports 37 and 49). In each case, the calculation was performed twice: First, by assuming the I-value of water was an experimentally based value of 78 eV (value proposed in Errata and Addenda for ICRU Report 73) and second, by recalculating the I-value theoretically. The discrepancy between predictions using ICRU elemental I-values and the commonly used tables of Janni was also investigated. Results: Errors due to neglecting the correction terms to the Bethe formula were calculated at less than 0.1% for biological tissues. Discrepancies greater than 1%, however, were estimated due to departures from simple Bragg additivity when a fixed I-value for water was imposed. When the I-value for water was calculated in a consistent manner to that for tissue, this disagreement was substantially reduced. The difference between SPR predictions when using Janni’s or ICRU tables for I-values was up to 1.6%. Experimental data used for materials of relevance to proton therapy suggest that the ICRU-derived values provide somewhat more accurate results (root-mean-square-error: 0.8% versus 1.6%). Conclusions: The conclusions from this study are that (1) the Bethe formula can be safely used for SPR calculations without correction terms; (2) simple Bragg additivity can be reasonably assumed for compound materials; (3) if simple Bragg additivity is assumed, then the I-value for water should be calculated in a consistent manner to that of the tissue of interest (rather than using an experimentally derived value); (4) the ICRU Report 37 I-values may provide a better agreement with experiment than Janni’s tables.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Multilevel segmentation of intracranial aneurysms in CT angiography images

Purpose: Segmentation of aneurysms plays an important role in interventional planning. Yet, the segmentation of both the lumen and the thrombus of an intracranial aneurysm in computed tomography angiography (CTA) remains a challenge. This paper proposes a multilevel segmentation methodology for efficiently segmenting intracranial aneurysms in CTA images. Methods: The proposed methodology first uses the lattice Boltzmann method (LBM) to extract the lumen part directly from the original image. Then, the LBM is applied again on an intermediate image whose lumen part is filled by the mean gray-level value outside the lumen, to yield an image region containing part of the aneurysm boundary. After that, an expanding disk is introduced to estimate the complete contour of the aneurysm. Finally, the contour detected is used as the initial contour of the level set with ellipse to refine the aneurysm. Results: The results obtained on 11 patients from different hospitals showed that the proposed segmentation was comparable with manual segmentation, and that quantitatively, the average segmentation matching factor (SMF) reached 86.99%, demonstrating good segmentation accuracy. Chan–Vese method, Sen’s model, and Luca’s model were used to compare the proposed method and their average SMF values were 39.98%, 40.76%, and 77.11%, respectively. Conclusions: The authors have presented a multilevel segmentation method based on the LBM and level set with ellipse for accurate segmentation of intracranial aneurysms. Compared to three existing methods, for all eleven patients, the proposed method can successfully segment the lumen with the highest SMF values for nine patients and second highest SMF values for the two. It also segments the entire aneurysm with the highest SMF values for ten patients and second highest SMF value for the one. This makes it potential for clinical assessment of the volume and aspect ratio of the intracranial aneurysms.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-D-202-04: Validation of Deformable Image Registration Algorithms for Head and Neck Adaptive Radiotherapy in Routine Clinical Setting

Purpose: To evaluate the ROI contours and accumulated dose difference using different deformable image registration (DIR) algorithms for head and neck (H&N) adaptive radiotherapy. Methods: Eight H&N cancer patients were randomly selected from the affiliated hospital. During the treatment, patients were rescanned every week with ROIs well delineated by radiation oncologist on each weekly CT. New weekly treatment plans were also re-designed with consistent dose prescription on the rescanned CT and executed for one week on Siemens CT-on-rails accelerator. At the end, we got six weekly CT scans from CT1 to CT6 including six weekly treatment plans for each patient. The primary CT1 was set as the reference CT for DIR proceeding with the left five weekly CTs using ANACONDA and MORFEUS algorithms separately in RayStation and the external skin ROI was set to be the controlling ROI both. The entire calculated weekly dose were deformed and accumulated on corresponding reference CT1 according to the deformation vector field (DVFs) generated by the two different DIR algorithms respectively. Thus we got both the ANACONDA-based and MORFEUS-based accumulated total dose on CT1 for each patient. At the same time, we mapped the ROIs on CT1 to generate the corresponding ROIs on CT6 using ANACONDA and MORFEUS DIR algorithms. DICE coefficients between the DIR deformed and radiation oncologist delineated ROIs on CT6 were calculated. Results: For DIR accumulated dose, PTV D95 and Left-Eyeball Dmax show significant differences with 67.13 cGy and 109.29 cGy respectively (Table1). For DIR mapped ROIs, PTV, Spinal cord and Left-Optic nerve show difference with −0.025, −0.127 and −0.124 (Table2). Conclusion: Even two excellent DIR algorithms can give divergent results for ROI deformation and dose accumulation. As more and more TPS get DIR module integrated, there is an urgent need to realize the potential risk using DIR in clinical.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-F-R-51: Radiomics in CT Perfusion Maps of Head and Neck Cancer

Purpose: The aim of this study was to test the predictive value of radiomics features of CT perfusion (CTP) for tumor control, based on a preselection of radiomics features in a robustness study. Methods: 11 patients with head and neck cancer (HNC) and 11 patients with lung cancer were included in the robustness study to preselect stable radiomics parameters. Data from 36 HNC patients treated with definitive radiochemotherapy (median follow-up 30 months) was used to build a predictive model based on these parameters. All patients underwent pre-treatment CTP. 315 texture parameters were computed for three perfusion maps: blood volume, blood flow and mean transit time. The variability of texture parameters was tested with respect to non-standardizable perfusion computation factors (noise level and artery contouring) using intraclass correlation coefficients (ICC). The parameter with the highest ICC in the correlated group of parameters (inter-parameter Spearman correlations) was tested for its predictive value. The final model to predict tumor control was built using multivariate Cox regression analysis with backward selection of the variables. For comparison, a predictive model based on tumor volume was created. Results: Ten parameters were found to be stable in both HNC and lung cancer regarding potentially non-standardizable factors after the correction for inter-parameter correlations. In the multivariate backward selection of the variables, blood flow entropy showed a highly significant impact on tumor control (p=0.03) with concordance index (CI) of 0.76. Blood flow entropy was significantly lower in the patient group with controlled tumors at 18 months (p<0.1). The new model showed a higher concordance index compared to the tumor volume model (CI=0.68). Conclusion: The preselection of variables in the robustness study allowed building a predictive radiomics-based model of tumor control in HNC despite a small patient cohort. This model was found to be superior to the volume-based model. The project was supported by the KFSP Tumor Oxygenation of the University of Zurich, by a grant of the Center for Clinical Research, University and University Hospital Zurich and by a research grant from Merck (Schweiz) AG.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-F-I-11: Software Development for 4D-CBCT Research of Real-Time-Image Gated Spot Scanning Proton Therapy

Purpose: To acquire correct information for inside the body in patient positioning of Real-time-image Gated spot scanning Proton Therapy (RGPT), utilization of tomographic image at exhale phase of patient respiration obtained from 4-dimensional Cone beam CT (4D-CBCT) has been desired. We developed software named “Image Analysis Platform” for 4D-CBCT researches which has technique to segment projection-images based on 3D marker position in the body. The 3D marker position can be obtained by using two axes CBCT system at Hokkaido University Hospital Proton Therapy Center. Performance verification of the software was implemented. Methods: The software calculates 3D marker position retrospectively by using matching positions on pair projection-images obtained by two axes fluoroscopy mode of CBCT system. Log data of 3D marker tracking are outputted after the tracking. By linking the Log data and gantry-angle file of projection-image, all projection-images are equally segmented to spatial five-phases according to marker 3D position of SI direction and saved to specified phase folder. Segmented projection-images are used for CBCT reconstruction of each phase. As performance verification of the software, test of segmented projection-images was implemented for sample CT phantom (Catphan) image acquired by two axes fluoroscopy mode of CBCT. Dummy marker was added on the images. Motion of the marker was modeled to move in 3D space. Motion type of marker is sin4 wave function has amplitude 10.0 mm/5.0 mm/0 mm, cycle 4 s/4 s/0 s for SI/AP/RL direction. Results: The marker was tracked within 0.58 mm accuracy in 3D for all images, and it was confirmed that all projection-images were segmented and saved to each phase folder correctly. Conclusion: We developed software for 4D-CBCT research which can segment projection-image based on 3D marker position. It will be helpful to create high quality of 4D-CBCT reconstruction image for RGPT.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-F-J-98: Improvement and Evaluation Of Deformation Image Registration On Parotid Glands During Radiation Therapy for Nasopharyngeal Cancer

Purpose: To quantitatively evaluate the strategic innovation and accuracy variation of deformation registration algorithm for parotid glands using the similarity Dice coefficient during the course of radiation therapy (RT) for nasopharyngeal cancer (NPC). Methods: Daily MVCT data for 10 patients with pathologically proven nasopharyngeal cancers were analyzed. The data were acquired using tomotherapy (TomoTherapy, Accuray) at the PLA General Hospital. The prescription dose to the primary target was 70Gy in 33 fractions. Two kinds of contours for parotid glands on daily MVCTs were obtained by populating these contours from planning CTs to the daily CTs via rigid-body registration with or without the rotation shifts using the in-house tools and the Adaptive plan software (Adaptive Plan, TomoTherapy), and were edited manually if necessary. The diffeomorphic Demons algorithm developed in the in-house tool was used to propagate the parotid structures from the daily CTs to planning CTs. The differences of the mapped parotid contours in two methods were evaluated using Dice similarity index (DSI). Two-tailed t-test analysis was carried out to compare the DSI changes during the course of RT. Results: For 10 patient plans, the accuracy of deformation image registration (DIR) with the rotation shift was obviously better than those without the rotation shift. The Dice scores of the ipsi- and contra-lateral parotids for with and without the rotation shifts were found to be correlated with each other [0.904±0.031 vs 0.919±0.030 (p<0.001); 0.900±0.031 vs 0.910±0.032 (p<0.001)]. The Dice scores for the parotids have shown the reduction with the changes of parotid volumes during RT. The DSI values between the first and last fraction were 0.932±0.020 vs 0.899±0.030 in 10 patient plans. Conclusion: DIR was successfully improved using the strategic innovation for ART. And the decrease of DIR accuracy has also been found during the delivery of fractionated radiotherapy. This work was supported in part by the grant from Chinese Natural Science Foundation (Grant No. 11105225).

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-F-J-132: Evaluation of CTV-To-PTV Expansion for Whole Breast Radiotherapy

Purpose: The current standard CTV-to-PTV expansion for whole breast radiotherapy (WBRT) is 7mm, as recommended by RTOG-1005.This expansion is derived from the uncertainty due to patient positioning (±5mm) and respiratory motion (±5mm). We evaluated the expansion needed for respiratory motion uncertainty using 4DCT. After determining the appropriate expansion margins, RT plans were generated to evaluate the reduction in heart and lung dose. Methods: 4DCT images were acquired during treatment simulation and retrospectively analyzed for 34 WBRT patients. Breast CTVs were contoured on the maximum inhale and exhale phase. Breast CTV displacement was measured in the L-R, A-P, and SUP-INF directions using rigid registration between phase images. Averaging over the 34 patients, we determined the margin due to respiratory motion. Plans were generated for 10 left-sided cases comparing the new expansion with the 7mm PTV expansion. Results: The results for respiratory motion uncertainty are shown in Table 1. Drawing on previous work by White et al at Princess Margaret Hospital (1) (see supporting document for reference) which studied the uncertainty due to patient positioning, we concluded that, in total, a 5mm expansion was sufficient. The results for our suggested PTV margin are shown in Table 2, combining the patient positioning results from White et al with our respiratory motion results. The planning results demonstrating the heart and lung dose differences in the 5mm CTV-to-PTV expanded plan compared to the 7mm plan are shown in Table 3. Conclusion: Our work evaluating the expansion needed for respiratory motion along with previous work evaluating the expansion needed for setup uncertainty shows that a CTV-to-PTV expansion of 5mm is acceptable and conservative. By reducing the PTV expansion, significant dose reduction to the heart and lung are achievable.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-F-J-180: A Reference Data Set for Testing Two Dimension Registration Algorithms

Purpose: To create and characterize a reference data set for testing image registration algorithms that transform portal image (PI) to digitally reconstructed radiograph (DRR). Methods: Anterior-posterior (AP) and Lateral (LAT) projection and DRR image pairs from nine cases representing four different anatomical sites (head and neck, thoracic, abdominal, and pelvis) were selected for this study. Five experts will perform manual registration by placing landmarks points (LMPs) on the DRR and finding their corresponding points on the PI using computer assisted manual point selection tool (CAMPST), a custom-made MATLAB software tool developed in house. The landmark selection process will be repeated on both the PI and the DRR in order to characterize inter- and -intra observer variations associated with the point selection process. Inter and an intra observer variation in LMPs was done using Bland-Altman (B&A) analysis and one-way analysis of variance. We set our limit such that the absolute value of the mean difference between the readings should not exceed 3mm. Later on in this project we will test different two dimension (2D) image registration algorithms and quantify the uncertainty associated with their registration. Results: Using one-way analysis of variance (ANOVA) there was no variations within the readers. When Bland-Altman analysis was used the variation within the readers was acceptable. The variation was higher in the PI compared to the DRR.ConclusionThe variation seen for the PI is because although the PI has a much better spatial resolution the poor resolution on the DRR makes it difficult to locate the actual corresponding anatomical feature on the PI. We hope this becomes more evident when all the readers complete the point selection. The reason for quantifying inter- and -intra observer variation tells us to what degree of accuracy a manual registration can be done. Research supported by William Beaumont Hospital Research Start Up Fund.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

SU-F-T-80: A Mobile Application for Intra-Operative Electron Radiotherapy Treatment Planning

Purpose: Intraoperative electron radiotherapy (IORT) poses a unique set of challenges for treatment planning. Planning must be performed in a busy operating room environment over a short timeframe often with little advance knowledge of the treatment depth or applicator size. Furthermore, IORT accelerators can have a large number of possible applicators, requiring extensive databooks that must be searched for the appropriate dosimetric parameters. The goal of this work is to develop a software tool to assist in the planning process that is suited to the challenges faced in the IORT environment. Methods: We developed a mobile application using HTML5 and Javascript that can be deployed to tablet devices suitable for use in the operating room. The user selects the desired treatment parameters cone diameter, bevel angle, and energy (a total of 141 datasets) and desired bolus. The application generates an interactive display that allows the user to dynamically select points on the depth-dose curve and to visualize the shape of the corresponding isodose contours. The user can indicate a prescription isodose line or depth. The software performs a monitor unit calculation and generates a PDF report. Results: We present our application, which is now used routinely in our IORT practice. It has been employed successfully in over 23 cases. The interactivity of the isodose distributions was found to be of particular use to physicians who are less-frequent IORT users, as well as for the education of residents and trainees. Conclusion: This software has served as a useful tool in IORT planning, and demonstrates the need for treatment planning tools that are designed for the specialized challenges encountered in IORT. This software is the subject of a license agreement with the IntraOp Medical Corporation. This software is the subject of a license agreement between Massachusetts General Hospital / Partners Healthcare and the IntraOp Medical Corporation. CLW is consulting on software development with the IntraOp Medical Corporation.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Survey of Surgical Oncology Fellowship Graduates 2005–2016: Insight into Initial Practice

Background: Despite burgeoning interest in Complex General Surgical Oncology (CGSO) fellowship training, little is reported about postgraduate employment. The goal of this study was to characterize CGSO graduates’ first employment and to identify factors that influenced this decision. Methods: The National Cancer Institute (NCI) and Society of Surgical Oncology developed and distributed an electronic survey to CGSO fellows who graduated from 2005 to 2016. Results: The survey response rate was 47% (237/509). Fifty-seven percent of respondents were first employed as faculty surgeons at a university-based/affiliated hospital, with 15% returning to their residency institution. The distribution of respondents’ current employment across the United States mirrored the locations of their hometowns. Eighty-five percent of respondents care for patients across at least three disease types, most commonly hepatopancreatobiliary (81%), esophagus/gastric (75%), and sarcoma (74%). Twenty-seven percent of respondents spend the majority of their time in one area of surgical oncology; melanoma, breast, and head/neck were the most common. Two-thirds of respondents (67%) reported that they performed either clinical or basic science research as part of their current position. Multiple factors influenced the decision of first faculty position. Conclusions: Most CGSO graduates are employed at academic medical centers across the country in proximity to NCI-designated centers, treat a variety of disease types, and spend a percentage of their time dedicated to clinical research.

62 RADIOLOGY AND NUCLEAR MEDICINE↗