bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐D‐207A‐01: Female Pelvic Synthetic CT Generation Based On Joint Shape and Intensity Analysis
Authors: Liu L , Jolly S , Cao Y , Vineberg K , Fessler J , Balter J 
Published: July 2016

Purpose:To develop a method for generating female pelvic synthetic CT (MRCT) images from a single MR scan and evaluate its utility in radiotherapy.Methods:Under IRB‐approval, an imaging sequence (T1_VIBE_Dixon) was acquired for 10 patients. This sequence yields 3 useful image volumes of different contrast (“in‐phase” T1‐weighted, fat and water). A previously published pelvic bone shape model was used to generate a rough bone mask for each patient. A modified fuzzy c‐means classification was performed on the multi spectral MR data, with a regularization term that utilizes the prior knowledge provided by the bone mask and addresses the intensity overlap between different tissue types. A weighted sum of classification probabilities with attenuation values yielded MRCT volumes. The mean absolute error (MAE) between MRCT and real CT on various regions was calculated following deformable alignment (Velocity). Intensity modulated Treatment plans based on actual CT and MRCT were made and compared.Results:The average/standard deviation of MAE across 10 patients was 10.1/6.7 HU for muscle, 6.7/4.6 HU for fat, 136.9/53.5 HU for bony tissues under 850 HU (97% of total bone volume), 188.9/119.3 HU for bony tissues above 850 HU and 17.3/13.3 HU for intrapelvic soft tissues. Calculated doses were comparable for plans generated on CT and calculated using MRCT densities or vice versa, with differences in PTV D99% (mean/σ) of (–0.1/0.2 Gy) and (0.3/0.2 Gy), PTV D0.5cc of (–0.3/0.2 Gy) and (–0.4/1.7 Gy). OAR differences were similarly small for comparable structures, with differences in bowel V50Gy of (–0.3/0.2%) and (0.0/0.2%), femur V30Gy of (0.7/1.2%) and (0.2/1.2%), sacrum V20GY of (0.0/0.1%) and (–0.1/1.1%) and mean pelvic V20Gy of (0.0/0.1%) and (0.6/1.8%).Conclusion:MRCT based on a single imaging sequence in the female pelvis is feasible, with acceptably small variations in attenuation estimates and calculated doses to target and critical organs.Work supported by NIHR01EB016079
SU‐D‐206‐03: Segmentation Assisted Fast Iterative Reconstruction Method for Cone‐Beam CT
Authors: Wu P , Mao T , Gong S , Wang J , Sheng K , Xie Y , Niu T 
Published: July 2016

Purpose:Total Variation (TV) based iterative reconstruction (IR) methods enable accurate CT image reconstruction from low‐dose measurements with sparse projection acquisition, due to the sparsifiable feature of most CT images using gradient operator. However, conventional solutions require large amount of iterations to generate a decent reconstructed image. One major reason is that the expected piecewise constant property is not taken into consideration at the optimization starting point. In this work, we propose an iterative reconstruction method for cone‐beam CT (CBCT) using image segmentation to guide the optimization path more efficiently on the regularization term at the beginning of the optimization trajectory.Methods:Our method applies general knowledge that one tissue component in the CT image contains relatively uniform distribution of CT number. This general knowledge is incorporated into the proposed reconstruction using image segmentation technique to generate the piecewise constant template on the first‐pass low‐quality CT image reconstructed using analytical algorithm. The template image is applied as an initial value into the optimization process.Results:The proposed method is evaluated on the Shepp‐Logan phantom of low and high noise levels, and a head patient. The number of iterations is reduced by overall 40%. Moreover, our proposed method tends to generate a smoother reconstructed image with the same TV value.Conclusion:We propose a computationally efficient iterative reconstruction method for CBCT imaging. Our method achieves a better optimization trajectory and a faster convergence behavior. It does not rely on prior information and can be readily incorporated into existing iterative reconstruction framework. Our method is thus practical and attractive as a general solution to CBCT iterative reconstruction.This work is supported by the Zhejiang Provincial Natural Science Foundation of China (Grant No. LR16F010001), National High‐tech R&D Program for Young Scientists by the Ministry of Science and Technology of China (Grant No. 2015AA020917).
SU‐D‐206‐07: CBCT Scatter Correction Based On Rotating Collimator
Authors: Yu G , Yin Y , Qiang L , Li B , Feng Z , Huang P , Li D 
Published: July 2016

Purpose:Scatter correction in cone‐beam computed tomography (CBCT) has obvious effect on the removal of image noise, the cup artifact and the increase of image contrast. Several methods using a beam blocker for the estimation and subtraction of scatter have been proposed. However, the inconvenience of mechanics and propensity to residual artifacts limited the further evolution of basic and clinical research. Here, we propose a rotating collimator‐based approach, in conjunction with reconstruction based on a discrete Radon transform and Tchebichef moments algorithm, to correct scatter‐induced artifacts.Methods:A rotating‐collimator, comprising round tungsten alloy strips, was mounted on a linear actuator. The rotating‐collimator is divided into 6 portions equally. The round strips space is evenly spaced on each portion but staggered between different portions. A step motor connected to the rotating collimator drove the blocker to around x‐ray source during the CBCT acquisition. The CBCT reconstruction based on a discrete Radon transform and Tchebichef moments algorithm is performed. Experimental studies using water phantom and Catphan504 were carried out to evaluate the performance of the proposed scheme.Results:The proposed algorithm was tested on both the Monte Carlo simulation and actual experiments with the Catphan504 phantom. From the simulation result, the mean square error of the reconstruction error decreases from 16% to 1.18%, the cupping (τcup) from 14.005% to 0.66%, and the peak signal‐to‐noise ratio increase from 16.9594 to 31.45. From the actual experiments, the induced visual artifacts are significantly reduced.Conclusion:We conducted an experiment on CBCT imaging system with a rotating collimator to develop and optimize x‐ray scatter control and reduction technique. The proposed method is attractive in applications where a high CBCT image quality is critical, for example, dose calculation in adaptive radiation therapy.We want to thank Dr. Lei Xing and Dr. Yong Yang in the Stanford University School of Medicine for this work. This work was jointly supported by NSFC (61471226), Natural Science Foundation for Distinguished Young Scholars of Shandong Province (JQ201516), and China Postdoctoral Science Foundation (2015T80739, 2014M551949).
SU‐D‐209‐01: Can Fluoroscopic Air‐Kerma Rates Be Reliably Measured with Solid‐State Meters?
Authors: Feng C , Ozus B , Thai L , Wagner L 
Published: July 2016

Purpose:Ionization chambers remain the standard for calibration of air‐kerma rate measuring devices. Despite their strong energy‐dependent response, solid state radiation detectors are increasingly used, primarily due to their efficiency in making standardized measurements. To test the reliability of these devices in measuring air‐kerma rates, we compared ion chambers measurements with solid‐state measurements for various mobile fluoroscopes operated at different beam qualities and air‐kerma rates.Methods:Six mobile fluoroscopes (GE OEC models 9800 and 9900) were used to generate test beams. Using various field sizes and dose rate controls, copper attenuators and a lead attenuator were placed at the image receptor in varying combinations to generate a range of air‐kerma rates. Air‐kerma rates at 30 centimeters from the image receptors were measured using two 6‐cm3 ion chambers with electrometers (Radcal, models 1015 and 9015) and two with solid state detectors (Unfors Xi and Raysafe X2). No error messages occurred during measurements. However, about two months later, one solid‐state device stopped working and was replaced by the manufacturer. Two out of six mobile fluoroscopic units were retested with the replacement unit.Results:Generally, solid state and ionization chambers agreed favorably well, with two exceptions. Before replacement of the detector, the Xi meter when set in the “RF High” mode deviated from ion chamber readings by factors of 2 and 10 with no message indicating error in measurement. When set in the “RF Low” mode, readings were within −4% to +3%. The replacement Xi detector displayed messages alerting the user when settings were not compatible with air‐kerma rates.Conclusion:Air‐kerma rates can be measured favorably well using solid‐state devices, but users must be aware of the possibility that readings can be grossly in error with no discernible indication for the deviation.
SU‐D‐207B‐02: Early Grade Classification in Meningioma Patients Combining Radiomics and Semantics Data
Authors: Coroller T , Bi W , Abedalthagafi M , Aizer A , Wu W , Greenwald N , Beroukhim R , Al‐Mefty O , Santagata S , Dunn I , Alexander B , Huang R , Aerts H 
Published: July 2016

Purpose:The clinical management of meningioma is guided by its grade and biologic behavior. Currently, diagnosis of tumor grade follows surgical resection and histopathologic review. Reliable techniques for pre‐operative determination of tumor behavior are needed. We investigated the association between imaging features extracted from preoperative gadolinium‐enhanced T1‐weighted MRI and meningioma grade.Methods:We retrospectively examined the pre‐operative MRI for 139 patients with de novo WHO grade I (63%) and grade II (37%) meningiomas. We investigated the predictive power of ten semantic radiologic features as determined by a neuroradiologist, fifteen radiomic features, and tumor location. Conventional (volume and diameter) imaging features were added for comparison. AUC was computed for continuous and χ2 for discrete variables. Classification was done using random forest. Performance was evaluated using cross validation (1000 iterations, 75% training and 25% validation). All p‐values were adjusted for multiple testing.Results:Significant association was observed between meningioma grade and tumor location (p<0.001) and two semantic features including intra‐tumoral heterogeneity (p<0.001) and overt hemorrhage (p=0.01). Conventional (AUC 0.61–0.67) and eleven radiomic (AUC 0.60–0.70) features were significant from random (p<0.05, Noether test). Median AUC values for classification of tumor grade were 0.57, 0.71, 0.72 and 0.77 respectively for conventional, radiomic, location, and semantic features after using random forest. By combining all imaging data (semantic, radiomic, and location), the median AUC was 0.81, which offers superior predicting power to that of conventional imaging descriptors for meningioma as well as radiomic features alone (p<0.05, permutation test).Conclusion:We demonstrate a strong association between radiologic features and meningioma grade. Pre‐operative prediction of tumor behavior based on imaging features offers promise for guiding personalized medicine and improving patient management.
SU‐D‐207B‐03: A PET‐CT Radiomics Comparison to Predict Distant Metastasis in Lung Adenocarcinoma
Authors: Coroller T , Yip S , Kim J , Lee S , Mak R , Aerts H 
Published: July 2016

Purpose:Early prediction of distant metastasis may provide crucial information for adaptive therapy, subsequently improving patient survival. Radiomic features that extracted from PET and CT images have been used for assessing tumor phenotype and predicting clinical outcomes. This study investigates the values of radiomic features in predicting distant metastasis (DM) in non‐small cell lung cancer (NSCLC).Methods:A total of 108 patients with stage II–III lung adenocarcinoma were included in this retrospective study. Twenty radiomic features were selected (10 from CT and 10 from PET). Conventional features (metabolic tumor volume, SUV, volume and diameter) were included for comparison. Concordance index (CI) was used to evaluate features prognostic value. Noether test was used to compute p‐value to consider CI significance from random (CI = 0.5) and were adjusted for multiple testing using false rate discovery (FDR).Results:A total of 70 patients had DM (64.8%) with a median time to event of 8.8 months. The median delivered dose was 60 Gy (range 33–68 Gy). None of the conventional features from PET (CI ranged from 0.51 to 0.56) or CT (CI ranged from 0.57 to 0.58) were significant from random. Five radiomics features were significantly prognostic from random for DM (p‐values < 0.05). Four were extracted from CT (CI = 0.61 to 0.63, p‐value <0.01) and one from PET which was also the most prognostic (CI = 0.64, p‐value <0.001).Conclusion:This study demonstrated significant association between radiomic features and DM for patients with locally advanced lung adenocarcinoma. Moreover, conventional (clinically utilized) metrics were not significantly associated with DM. Radiomics can potentially help classify patients at higher risk of DM, allowing clinicians to individualize treatment, such as intensification of chemotherapy) to reduce the risk of DM and improve survival.R.M. has consulting interests with Amgen.
SU‐F‐SPS‐01: Accuracy of the Small Field Dosimetry Using Acuros XB and AAA Dose Calculation Algorithms of Eclipse Treatment Planning System Within and Beyond Heterogeneous Media for Trubeam 2.0 Unit
Authors: Codel G , Serin E , Pacaci P , Sanli E , Cebe M , Mabhouti H , Doyuran M , Kucukmorkoc E , Kucuk N , Altinok A , Canoglu D , Acar H , Caglar Ozkok H 
Published: July 2016

Purpose:In this study, the comparison of dosimetric accuracy of Acuros XB and AAA algorithms were investigated for small radiation fields incident on homogeneous and heterogeneous geometriesMethods:Small open fields of Truebeam 2.0 unit (1×1, 2×2, 3×3, 4×4 fields) were used for this study. The fields were incident on homogeneous phantom and in house phantom containing lung, air, and bone inhomogeneities. Using the same film batch, the net OD to dose calibration curve was obtaine dusing Trubeam 2.0 for 6 MV, 6 FFF, 10 MV, 10 FFF, 15 MV energies by delivering 0‐ 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. The dosimetric accuracy of Acuros XB and AAA algorithms in the presence of the inhomogeneities was compared against EBT3 film dosimetryResults:Open field tests in a homogeneous phantom showed good agreement betweent wo algorithms and measurement. For Acuros XB, minimum gamma analysis passin grates between measured and calculated dose distributions were 99.3% and 98.1% for homogeneousand inhomogeneous fields in thecase of lung and bone respectively. For AAA, minimum gamma analysis passingrates were 99.1% and 96.5% for homogeneous and inhomogeneous fields respectively for all used energies and field sizes.In the case of the air heterogeneity, the differences were larger for both calculations algorithms. Over all, when compared to measurement, theAcuros XB had beter agreement than AAA.Conclusion:The Acuros XB calculation algorithm in the TPS is an improvemen tover theexisting AAA algorithm. Dose discrepancies were observed for in the presence of air inhomogeneities.
SU‐F‐SPS‐05: Experimental Validation of Peripheral Dose Distribution of Electron Beams for Eclipse Electron Monte Carlo Algorithm
Authors: Cebe M , Pacaci P , Mabhouti H , Codel G , Sanli E , Serin E , Kucuk N , Kucukmorkoc E , Doyuran M , Canoglu D , Altinok A , Acar H , Caglar Ozkok H 
Published: July 2016

Purpose:In this study, the two available calculation algorithms of the Varian Eclipse treatment planning system(TPS), the electron Monte Carlo(eMC) and General Gaussian Pencil Beam(GGPB) algorithms were used to compare measured and calculated peripheral dose distribution of electron beams.Methods:Peripheral dose measurements were carried out for 6, 9, 12, 15, 18 and 22 MeV electron beams of Varian Triology machine using parallel plate ionization chamber and EBT3 films in the slab phantom. Measurements were performed for 6×6, 10×10 and 25×25cm2 cone sizes at dmax of each energy up to 20cm beyond the field edges. Using the same film batch, the net OD to dose calibration curve was obtained for each energy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution measured using parallel plate ionization chamber and EBT3 film and calculated by eMC and GGPB algorithms were compared. The measured and calculated data were then compared to find which algorithm calculates peripheral dose distribution more accurately.Results:The agreement between measurement and eMC was better than GGPB. The TPS underestimated the out of field doses. The difference between measured and calculated doses increase with the cone size. The largest deviation between calculated and parallel plate ionization chamber measured dose is less than 4.93% for eMC, but it can increase up to 7.51% for GGPB. For film measurement, the minimum gamma analysis passing rates between measured and calculated dose distributions were 98.2% and 92.7% for eMC and GGPB respectively for all field sizes and energies.Conclusion:Our results show that the Monte Carlo algorithm for electron planning in Eclipse is more accurate than previous algorithms for peripheral dose distributions. It must be emphasized that the use of GGPB for planning large field treatments with 6 MeV could lead to inaccuracies of clinical significance.
SU‐F‐E‐07: Web‐Based Training for Radiosurgery: Methods and Metrics for Global Reach
Authors: Schulz R , Thomas E , Popple R , Fiveash J , Jacobsen E 
Published: July 2016

Purpose:Webinars have become an evolving tool with greater or lesser success in reaching health care providers (HCPs). This study seeks to assess best practices and metrics for success in webinar deployment for optimal global reach.Methods:Webinars have been developed and launched to reach practicing health care providers in the field of radiation oncology and radiosurgery. One such webinar was launched in early February 2016. “Multiple Brain Metastases & Volumetric Modulated Arc Radiosurgery: Refining the Single‐Isocenter Technique to Benefit Surgeons and Patients” presented by Drs. Fiveash and Thomas from UAB was submitted to and accredited by the Institute for Medical Education as qualifying for CME as well as MDCB for educational credit for dosimetrists, in order to encourage participation. MedicalPhysicsWeb was chosen as the platform to inform attendees regarding the webinar. Further IME accredited the activity for 1 AMA PRA Category 1 credit for physicians & medical physicists. The program was qualified by the ABR in meeting the criteria for self‐assessment towards fulfilling MOC requirements. Free SAMs credits were underwritten by an educational grant from Varian Medical Systems.Results:The webinar in question attracted 992 pre‐registrants from 66 countries. Outside the US and Canada; 11 were from the Americas; 32 were from Europe; 9 from the Middle East and Africa. Australasia and the Indian subcontinent represented the remaining 14 countries. Pre‐registrants included 423 Medical Physicists, 225 Medical Dosimetrists, 24 Radiation Therapists, 66 Radiation Oncologists & other.Conclusion:The effectiveness of CME and SAM‐CME programs such as this can be gauged by the high rate of respondents who state an intention to change practice habits, a primary goal of continuing medical education and self‐assessment. This webinar succeeded in being the most successful webinar on Medical Physics Web as measured by pre‐registration, participation and participation to pre‐registration ratio.R.A. Schulz is an employee of Varian Medical Systems
SU‐F‐E‐13: Design and Fabrication of Gynacological Brachytherapy Shielding & Non Shielding Applicators Using Indigenously Developed 3D Printing Machine
Authors: Shanmugam S 
Published: July 2016

Purpose:In this innovative work we have developed Gynecological Brachytherapy shielding & Non Shielding Applicators and compared with the commercially available applicators by using the indigenously developed 3D Printing machine.Methods:We have successfully indigenously developed the 3D printing machine. Which contain the 3 dimensional motion platform, Heater unit, base plate, ect… To fabricate the Gynecological Brachytherapy shielding & non shielding applicators the 3D design were developed in the computer as virtual design. This virtual design is made in a CAD computer file using a 3D modeling program. Separate programme for the shielding & non shielding applicators. We have also provided the extra catheter insert provision in the applicator for the multiple catheter. The DICOM file of the applicator were then converted to stereo Lithography file for the 3D printer. The shielding & Non Shielding Applicators were printed on a indigenously developed 3D printer material. The same dimensions were used to develop the applicators in the acrylic material also for the comparative study. A CT scan was performed to establish an infill‐density calibration curve as well as characterize the quality of the print such as uniformity and the infill pattern. To commission the process, basic CT and dose properties of the printing materials were measured in photon beams and compared against water and soft tissue. Applicator were then scanned to confirm the placement of multiple catheter position. Finally dose distributions with rescanned CTs were compared with those computer‐generated applicators.Results:The doses measured from the ion Chamber and X‐Omat film test were within 2%. The shielded applicator reduce the rectal dose comparatively with the non shielded applicator.Conclusion:As of submission 3 unique cylinders have been designed, printed, and tested dosimetrically. A standardizable workflow for commissioning custom 3D printed applicators was codified and will be reported.
SU‐F‐P‐07: Applying Failure Modes and Effects Analysis to Treatment Planning System QA
Authors: Mathew D , Alaei P 
Published: July 2016

Purpose:A small‐scale implementation of Failure Modes and Effects Analysis (FMEA) for treatment planning system QA by utilizing methodology of AAPM TG‐100 report.Methods:FMEA requires numerical values for severity (S), occurrence (O) and detectability (D) of each mode of failure. The product of these three values gives a risk priority number (RPN). We have implemented FMEA for the treatment planning system (TPS) QA for two clinics which use Pinnacle and Eclipse TPS. Quantitative monthly QA data dating back to 4 years for Pinnacle and 1 year for Eclipse have been used to determine values for severity (deviations from predetermined doses at points or volumes), and occurrence of such deviations. The TPS QA protocol includes a phantom containing solid water and lung‐ and bone‐equivalent heterogeneities. Photon and electron plans have been evaluated in both systems. The dose values at multiple distinct points of interest (POI) within the solid water, lung, and bone‐equivalent slabs, as well as mean doses to several volumes of interest (VOI), have been re‐calculated monthly using the available algorithms.Results:The computed doses vary slightly month‐over‐month. There have been more significant deviations following software upgrades, especially if the upgrade involved re‐modeling of the beams. TG‐100 guidance and the data presented here suggest an occurrence (O) of 2 depending on the frequency of re‐commissioning the beams, severity (S) of 3, and detectability (D) of 2, giving an RPN of 12.Conclusion:Computerized treatment planning systems could pose a risk due to dosimetric errors and suboptimal treatment plans. The FMEA analysis presented here suggests that TPS QA should immediately follow software upgrades, but does not need to be performed every month.