bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐P‐33: Critical Role of T2‐Weighted Imaging Combined with Diffusion‐Weighted Imaging of MRI in Diagnosis of Loco‐Regional Recurrent Esophageal Cancer After Radical Surgery
Authors: Deng G , Liang N , Xie J , Zhang J , Qiao L , Luo H , Zhang J 
Published: June 2015

Purpose:We perform this study to investigate the diagnostic efficacy of T2‐weighted MRI (T2WI) and diffusion‐weighted MRI (DWI) in confirming local relapses of esophageal cancer in patients highly suspected of recurrence after eradicating surgery.Methods:Forty‐two postoperative esophageal cancer patients with clinical suspicions of cancer recurrence underwent 3.0T MRI applying axial, coronal, sagittal T2WI and axial DWI sequences. Two experienced radiologists (R1 and R2) both used two methods (T2WI, T2WI+DWI) to observe the images, and graded the patients ranging from 1 to 5 to represent severity of the disease based on visual signal intensity (patients equal to or more than grade 3 was confirmed as recurrent disease)Results:27/42patients were verified of recurrent disease by pathologic findings and/or imaging findings during follow‐up. The sensitivity, specificity and accuracy of R1 applying T2WI+DWI are 96%, 87% and 93% versus 81%, 80% and 77% on T2WI, these figures by R2 were 96%, 93% and 95% versus 89%, 93% and 90%. The receiver operating curve (ROC) analyses suggest that both of the two readers can obtain better accuracy when adding DWI to T2WI compared with T2WI alone. Kappa test between R1 and R2 indicates excellent inter‐observer agreement on T2WI+DWI.Conclusion:Standard T2WI in combination DWI can achieve better accuracy than T2WI alone in diagnosing local recurrence of esophageal cancer, and improve consistency between different readers.
SU‐E‐P‐46: Clinical Acceptance Testing and Implementation of a Portable CT Unit
Authors: LaFrance M , Marsh S , Hicks R , O'Donnell‐Moran G 
Published: June 2015

Purpose:Planning for the first installation in New England of a new portable CT unit to be used in the Operating Room required the integration of many departments including Surgery, Neurosurgery, Information Services, Clinical Engineering, Radiology and Medical Physics/Radiation Safety. Acceptance testing and the quality assurance procedures were designed to optimize image quality and patient and personnel radiation exposure.Methods:The vendor's protocols were tested using the CT Dosimetry phantoms. The system displayed the CTDIw instead of the CTDIvol while testing the unit. Radiation exposure was compared to existing CT scanners from installed CT units throughout the facility. Brainlab measures all 4 periphery slots on the CT Dosimetry phantom. The ACR measures only the superior slot for the periphery measurement. A comprehensive radiation survey was also performed for several locations.Results:The CTDIvol measurements were comparable for the following studies: brain, C‐Spine, and sinuses. However, the mobile CT measurements were slightly higher than other CT units but within acceptable tolerance if measured using the ACR method.Based on scatter measurements, it was determined if any personnel were to stay in the OR Suite during image acquisition that the appropriate lead apron and thyroid shields had to be worn.In addition, to reduce unnecessary scatter, there were two mobile 6 foot wide shields (1/16″ lead equivalent) available to protect personnel in the room and adjacent areas.Conclusion:Intraoperative CT provides the physician new opportunities for evaluation of the progression of surgical resections and device placement at the cost of increasing the amount of trained personnel required to perform this procedure. It also brings with it challenges to keep the radiation exposure to the patients and staff within reasonable limits.
SU‐E‐P‐53: A Plan Quality Comparison for Volumetric‐Modulated Arc Therapy by Different Maximum Delivery Time Setting for Cervical and Upper Thoracic Esophageal Cancer
Authors: Yang J , Liu D , Miao M , Jing Z , Li Z 
Published: June 2015

Purpose:To evaluate and compare the treatment plan quality of volumetric modulated arc therapy (VMAT) plans using different constrain conditions of delivery time for cervical and upper thoracic esophageal cancer.Methods:In this retrospective study, single‐arc VMAT plans were generated with the Oncentra 4.3v system for twenty cervical and upper thoracic esophageal cancer cases. The maximum delivery time were set systematically various as 80s, 110s and 150s. Planning objectives were to deliver 60 Gy in 30 fractions to 95% of PTV, with maximum doses of spinal cord <45 Gy, V5Gy<50%, V10Gy<40%, V20Gy<25% and V30Gy<20% to the lung tissue. All of the three groups of VMAT plans were clinical acceptable. For plan evaluation statistics, PTVDmax, PTVDmin, PTVDmean, PTVD100∼D2, PTVV110∼V90, CordDmax, CordD2, CORDD40, LungDmean, LungV5∼V40 were analyzed and compared by SPSS 20.0.Results:The dose distribution quality of plans generated by different maximum delivery time settings was assessed by anova and non‐parametric tests. No significant differences were found for target and OAR parameters except for the hight dose volume of PTV. The maximum dose (p = 0.034) and D2% (p = 0.030) of PTV in plans with 80s setting were detected significant lower than other plans by anova analysis. And for the maximum dose (p = 0.039) of PTV, it was showed the same results by non‐parametric tests.Conclusion:Considering of the quality of VMAT plans and the treatment time, 80s as the initial parameters of the maximum delivery time would be a better choice than 110s and 150s for cervical and upper esophageal cancer.
SU‐E‐I‐20: Comprehensive Quality Assurance Test of Second Generation Toshiba Aquilion Large Bore CT Simulator Based On AAPM TG‐66 Recommendations
Authors: Zhang D 
Published: June 2015

Purpose:AAPM radiation therapy committee task group No. 66 (TG‐66) published a report which described a general approach to CT simulator QA. The report outlines the testing procedures and specifications for the evaluation of patient dose, radiation safety, electromechanical components, and image quality for a CT simulator. The purpose of this study is to thoroughly evaluate the performance of a second generation Toshiba Aquilion Large Bore CT simulator with 90 cm bore size (Toshiba, Nasu, JP) based on the TG‐66 criteria. The testing procedures and results from this study provide baselines for a routine QA program.Methods:Different measurements and analysis were performed including CTDIvol measurements, alignment and orientation of gantry lasers, orientation of the tabletop with respect to the imaging plane, table movement and indexing accuracy, Scanogram location accuracy, high contrast spatial resolution, low contrast resolution, field uniformity, CT number accuracy, mA linearity and mA reproducibility using a number of different phantoms and measuring devices, such as CTDI phantom, ACR image quality phantom, TG‐66 laser QA phantom, pencil ion chamber (Fluke Victoreen) and electrometer (RTI Solidose 400).Results:The CTDI measurements were within 20% of the console displayed values. The alignment and orientation for both gantry laser and tabletop, as well as the table movement and indexing and scanogram location accuracy were within 2mm as specified in TG66. The spatial resolution, low contrast resolution, field uniformity and CT number accuracy were all within ACR's recommended limits. The mA linearity and reproducibility were both well below the TG66 threshold.Conclusion:The 90 cm bore size second generation Toshiba Aquilion Large Bore CT simulator that comes with 70 cm true FOV can consistently meet various clinical needs. The results demonstrated that this simulator complies with the TG‐66 protocol in all aspects including electromechanical component, radiation safety component, and image quality component.Employee of Toshiba America Medical Systems
SU‐E‐I‐86: Ultra‐Low Dose Computed Tomography Attenuation Correction for Pediatric PET CT Using Adaptive Statistical Iterative Reconstruction (ASiR™)
Authors: Brady S , Shulkin B 
Published: June 2015

Purpose:To develop ultra‐low dose computed tomography (CT) attenuation correction (CTAC) acquisition protocols for pediatric positron emission tomography CT (PET CT).Methods:A GE Discovery 690 PET CT hybrid scanner was used to investigate the change to quantitative PET and CT measurements when operated at ultra‐low doses (10–35 mAs). CT quantitation: noise, low‐contrast resolution, and CT numbers for eleven tissue substitutes were analyzed in‐phantom. CT quantitation was analyzed to a reduction of 90% CTDIvol (0.39/3.64; mGy) radiation dose from baseline. To minimize noise infiltration, 100% adaptive statistical iterative reconstruction (ASiR) was used for CT reconstruction. PET images were reconstructed with the lower‐dose CTAC iterations and analyzed for: maximum body weight standardized uptake value (SUVbw) of various diameter targets (range 8–37 mm), background uniformity, and spatial resolution. Radiation organ dose, as derived from patient exam size specific dose estimate (SSDE), was converted to effective dose using the standard ICRP report 103 method. Effective dose and CTAC noise magnitude were compared for 140 patient examinations (76 post‐ASiR implementation) to determine relative patient population dose reduction and noise control.Results:CT numbers were constant to within 10% from the non‐dose reduced CTAC image down to 90% dose reduction. No change in SUVbw, background percent uniformity, or spatial resolution for PET images reconstructed with CTAC protocols reconstructed with ASiR and down to 90% dose reduction. Patient population effective dose analysis demonstrated relative CTAC dose reductions between 62%–86% (3.2/8.3−0.9/6.2; mSv). Noise magnitude in dose‐reduced patient images increased but was not statistically different from pre dose‐reduced patient images. Conclusion: Using ASiR allowed for aggressive reduction in CTAC dose with no change in PET reconstructed images while maintaining sufficient image quality for co‐localization of hybrid CT anatomy and PET radioisotope uptake.
SU‐E‐I‐91: Quantitative Assessment of Early Hepatocellular Carcinoma and Cavernous Hemangioma of Live Using In‐Line Phase‐Contrast X‐Ray Imaging
Authors: Duan J 
Published: June 2015

Purpose:To investigate the potential utility of in‐line phase‐contrast imaging (ILPCI) technique with synchrotron radiation in detecting early hepatocellular carcinoma and cavernous hemangioma of live using in vitro model system.Methods:Without contrast agents, three typical early hepatocellular carcinoma specimens and three typical cavernous hemangioma of live specimens were imaged using ILPCI. To quantitatively discriminate early hepatocellular carcinoma tissues and cavernous hemangioma tissues, the projection images texture feature based on gray level co‐occurrence matrix (GLCM) were extracted. The texture parameters of energy, inertia, entropy, correlation, sum average, sum entropy, difference average, difference entropy and inverse difference moment, were obtained respectively.Results:In the ILPCI planar images of early hepatocellular carcinoma specimens, vessel trees were clearly visualized on the micrometer scale. Obvious distortion deformation was presented, and the vessel mostly appeared as a ‘dry stick’. Liver textures appeared not regularly. In the ILPCI planar images of cavernous hemangioma of live specimens, typical vessels had not been found compared with the early hepatocellular carcinoma planar images. The planar images of cavernous hemangioma of live specimens clearly displayed the dilated hepatic sinusoids with the diameter of less than 100 microns, but all of them were overlapped with each other. The texture parameters of energy, inertia, entropy, correlation, sum average, sum entropy, and difference average, showed a statistically significant between the two types specimens image (P<0.01), except the texture parameters of difference entropy and inverse difference moment(P>0.01).Conclusion:The results indicate that there are obvious changes in morphological levels including vessel structures and liver textures. The study proves that this imaging technique has a potential value in evaluating early hepatocellular carcinoma and cavernous hemangioma of live.
SU‐E‐J‐01: MR Guided Pulsed Focused Ultrasound Mediated Targeted Chemotherapeutic‐Agent Delivery in Management of Prostate Cancer
Authors: Chen L , Cvetkovic D , Gupta R , Wang B , Ma C 
Published: June 2015

Purpose:The purpose of this study is to investigate an innovative approach to prostate cancer therapy using nanodroplet‐encapsulated drugs combined with pulsed high intensity focused ultrasound (pFUS) treatment. Pulsed FUS treatment improves localized drug release from the carrier and enhances intracellular uptake, which ensures temporal and spatial control of local drug delivery while reducing systemic toxicity from the drugs. Methods: LNCaP cells were implanted into the prostates of nude mice. Tumor growth was monitored using MRI. The tumor—bearing mice were randomly divided into 5 groups (n=5 for each group). Group 1, animals were treated with an IV injection of docetaxel (DTX)‐encapsulated nanodroplets (ND‐DTX) + pFUS. Animals in Group 2 were treated with pFUS alone. Animals in Group 3 were injected (IV) with DTX‐encapsulated nanodroplets alone, Group 4 received free DTX alone and Group 5 was used as a control group. After treatment, animals were allowed to survive for 3 weeks. Tumor growth delay was monitored by MRI (resolution: <0.2mm). The formulation of the DTX‐encapsulated nanodroplets was: DTX dose 20 mg/kg, Nanoemulsion composition 0.5% PTX, 1% perfluorocarbon and 2% stabilizing block copolymer. Ultrasound treatment parameters were 1MHz, 25W acoustic power, 10% duty cycle and 60 sec for each sonication.Results:Our results showed that Group 1, in which animals were treated with an IV injection of ND‐DTX + pFUS, exhibited the most tumor growth control (50%–30%) among all groups. All other groups showed similar tumor growth to that of the control group after the treatment (within statistical uncertainties).Conclusion:Our preliminary results showed a great potential for prostate cancer therapy using targeted DTX+ nanodroplets, which could be activated by pFUS. Further animal studies are warranted to confirm the results. The enhancement effect of pFUS on targeted drug delivery needs to be investigated quantitatively.
SU‐E‐J‐05: Use of a 6D Couch for Real‐Time Full Translational and Rotational Head Motion Correction During Stereotactic Radiosurgery: A Feasibility Study
Authors: Liu X , Belcher AH , Grelewicz Z , Wiersma RD 
Published: June 2015

Purpose:This work presents a methodology for correcting full translational and rotational head motion deviations during frameless image‐guided stereotactic radiosurgery (SRS) procedures with a robotic 6D couch. The main objective is to design control algorithms which optimize the correction motion of a 6D couch when sub‐millimeter/sub‐degree accuracy requirements are necessary in SRS.Methods:The system includes 6D position tracking and a 6D couch with three serially connected platforms. The bottom platform controls yaw compensation (around the z axis), the middle one generates full 3D translational motion, and the top platform controls both pitch (around X) and roll (around Y) motion with two linear actuators. Based on the 6D position of the head and the couch at each moment, the desired 6D couch position for correction is calculated, with the required 6 actuator outputs computed by an inverse algorithm accordingly. To minimize their responsive motion, the actuators take action only after the head position deviates beyond certain predetermined thresholds, and for each action the head is returned to the center of desired 6D treatment position.Results:With computer simulation, head motion of an SRS patient was modeled and the simulated couch was used to compensate for this motion in real‐time. For a 15‐minute test with a 0.3 mm and 0.15 degree target position tolerance, the corrected 6D head position was within tolerance over 99.5% of the time. The actuators moved approximately 80 times during the simulation, and the total actuator motion for translational correction was around 205 mm.Conclusion:We investigated a control approach for full translational and rotational head motion correction with a 6D couch. The simulations demonstrated that with moderate correction motion of a 6D couch, the control performance meets real‐time submillimeter and sub‐degree accuracy requirement of frameless SRS.The research is funded by the American Cancer Society (ACS) grant. The grant name is: Frameless SRS Based on Robotic Head Motion Cancellation. The grant number is: RSG‐13‐313‐01‐CCE
SU‐E‐J‐07: IGRT Gently: Evaluating Imaging Dose in Phantoms of Different Sizes
Authors: Morris B , Duggar W , Stanford J , Yang C 
Published: June 2015

Purpose:IGRT imaging procedures have emerged as a common method of patient position verification in radiotherapy, though imaging dose is generally neglected in the treatment plan. Consequently, evaluating and optimizing the dose from these procedures is worthwhile. This process is especially important for children, who are more radiosensitive than adults. The aim of this work was to gain some understanding of the relative doses involved with various XVI‐preset parameters for an “adult” and “child” phantom set, with the hopes that imaging dose for a child can be reduced.Methods:32 and 16cm CTDI‐phantoms were used as surrogates for adult and child torsos, respectively. Dose was measured in the central and peripheral chamber positions of the phantoms. CBCT scans were made for both phantoms using Elekta's Chest‐preset to establish a dose baseline. The child‐phantom was then scanned using the Elekta Head and Neck (HN) preset. A modified HN‐preset (named Peds Abd‐pelvis) was also created with a doubled mAs to maintain a reduction in dose to the child‐phantom (relative to the baseline), while providing clinically‐usable image quality.Results:The baseline dose to the child‐phantom from the Chest‐preset was 310% that of the adult‐phantom for the center chamber position and 150% at the periphery. An average dose reduction of 97% was obtained in the childphantom by switching from the Chest‐preset to the HN‐preset, while the Peds Abd‐pelvis‐preset similarly reduced the dose by an average of 92%.Conclusion:XVI‐preset parameters significantly affect dose, and should be optimized to reduce dose, while ensuring clinically‐usable image quality. Using a modified imaging preset (Peds Abd‐pelvis‐preset) greatly reduced the dose to the child‐phantom compared to the dose for the Chest‐preset for both the child and adult‐phantoms. This outcome provides support for the development of child‐specific protocols for IGRT imaging in pediatric patients.
SU‐E‐J‐09: Image Quality Comparison and Dose Quantification for 2.5 MV
Authors: Stowe M , DiCostanzo D , Ayan A , Woollard J , Gupta N 
Published: June 2015

Purpose:To compare the image quality of the 2.5MV imaging beam (2.5X‐IMB) to that of a 6MV beam and to quantify the imaging dose of a 2.5X‐IMB for constancy as specified by AAPM TG‐142Methods:The image quality of the 2.5X‐IMB was compared to the 6MV imaging beam using the SNC ImagePro MV‐QA phantom and the Varian supplied Las Vegas phantom (LVP). High resolution (1280×1280×16, 2 frames at 1.5MU/frame) and low resolution (640×640×16, 2 frames at 0.75MU/frame) images were compared for each phantom. MV‐QA phantom images were evaluated quantitatively, and the LVP images were evaluated qualitatively. The imaging dose for 2.5X‐IMB was quantified using the procedure outlined in TG51. PTWCC13‐31013 chambers were used to measure a percent depth dose (PDD) curve for the 2.5X‐IMB. All the factors described in TG51 were calculated using the 2.5X‐IMB and a PTW30013 farmer chamber.Results:A comparison between 2.5X‐IMB and 6MV image quality was performed both visually and with DoseLab software. The optimal window and level were set for each image of the LVP by the user. Visual inspection showed greater contrast resolution with the 2.5MV beam, but no significant difference with the change in imaging resolution. DoseLab reported similar spatial resolutions between the two energies, but the contrast‐to‐noise ratio (CNR) was greater for 2.5MV. The PDDx(10cm) for a 10x10cm2 field was measured to be 51.5%. Although this PDD value is off the scale of Figure 4 in TG51, the trend of the curve corresponding to the PTW31003 (equivalent) chamber led to an approximate kQ value of 1.00.Conclusion:When compared to 6MV imaging, 2.5X‐IMB results in a better CNR. At low resolution, the DoseLab results for the two energies are comparable, but visual analysis favors the 2.5X‐IMB images. Imaging dose was quantified for the 2.5X‐IMB after following the TG51 methodology with appropriate approximations.
SU‐E‐J‐11: Measurement of Eye Lens Dose for Varian On‐Board Imaging with Different CBCT Acquisition Techniques
Authors: Deshpande S , Dhote D , Kumar R , Thakur K 
Published: June 2015

Purpose:To measure actual patient eye lens dose for different cone beam computed tomography (CBCT) acquisition protocol of Varian's On Board Imagining (OBI) system using Optically Stimulated Luminescence (OSL) dosimeter and study the eye lens dose with patient geometry and distance of isocenter to the eye lensMethods:OSL dosimeter was used to measure eye lens dose of patient. OSL dosimeter was placed on patient forehead center during CBCT image acquisition to measure eye lens dose. For three different cone beam acquisition protocol (standard dose head, low dose head and high quality head) of Varian On‐Board Imaging, eye lens doses were measured. Measured doses were correlated with patient geometry and distance between isocenter to eye lens.Results:Measured eye lens dose for standard dose head was in the range of 1.8 mGy to 3.2 mGy, for high quality head protocol dose was in range of 4.5mGy to 9.9 mGy whereas for low dose head was in the range of 0.3mGy to 0.7mGy. Dose to eye lens is depends upon position of isocenter. For posterioraly located tumor eye lens dose is less.Conclusion:From measured doses it can be concluded that by proper selection of imagining protocol and frequency of imaging, it is possible to restrict the eye lens dose below the new limit set by ICRP. However, undoubted advantages of imaging system should be counter balanced by careful consideration of imaging protocol especially for very intense imaging sequences for Adoptive Radiotherapy or IMRT