bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐146: A Research of PET‐CT SUV Range for the Online Dose Verification in Carbon Ion Radiation Therapy
Authors: Sun L , Hu W , Moyers M , Zhao J , Hsi W 
Published: June 2015

Purpose:Positron‐emitting isotope distributions can be used for the image fusion of the carbon ion planning CT and online target verification PETCT, after radiation in the same decay period,the relationship between the same target volume and the SUV value of different every single fraction dose can be found,then the range of SUV for the radiation target could be decided.So this online range also can provide reference for the correlation and consistency in planning target dose verification and evaluation for the clinical trial.Methods:The Rando head phantom can be used as real body,the 10cc cube volume target contouring is done,beam ISO Center depth is 7.6cm and the 90 degree fixed carbon ion beams should be delivered in single fraction effective dose of 2.5GyE,5GyE and 8GyE.After irradiation,390 seconds later the 30 minutes PET‐CT scanning is performed,parameters are set to 50Kg virtual weight,0.05mCi activity.MIM Maestro is used for the image processing and fusion,five 16mm diameter SUV spheres have been chosen in the different direction in the target.The average SUV in target for different fraction dose can be found by software.Results:For 10cc volume target,390 seconds decay period,the Single fraction effective dose equal to 2.5Gy,Ethe SUV mean value is 3.42,the relative range is 1.72 to 6.83;Equal to 5GyE,SUV mean value is 9.946,the relative range is 7.016 to 12.54;Equal or above to 8GyE,SUV mean value is 20.496,the relative range is 11.16 to 34.73.Conclusion:Making an evaluation for accuracy of the dose distribution using the SUV range which is from the planning CT with after treatment online PET‐CT fusion for the normal single fraction carbon ion treatment is available.Even to the plan which single fraction dose is above 2GyE,in the condition of other parameters all the same,the SUV range is linearly dependent with single fraction dose,so this method also can be used in the hyper‐fraction treatment plan.
SU‐E‐J‐147: Monte Carlo Study of the Precision and Accuracy of Proton CT Reconstructed Relative Stopping Power Maps
Authors: Dedes G , Asano Y , Arbor N , Dauvergne D , Letang J , Testa E , Rit S , Parodi K 
Published: June 2015

Purpose:The quantification of the intrinsic performances of proton computed tomography (pCT) as a modality for treatment planning in proton therapy. The performance of an ideal pCT scanner is studied as a function of various parameters.Methods:Using GATE/Geant4, we simulated an ideal pCT scanner and scans of several cylindrical phantoms with various tissue equivalent inserts of different sizes. Insert materials were selected in order to be of clinical relevance. Tomographic images were reconstructed using a filtered backprojection algorithm taking into account the scattering of protons into the phantom. To quantify the performance of the ideal pCT scanner, we study the precision and the accuracy with respect to the theoretical relative stopping power ratios (RSP) values for different beam energies, imaging doses, insert sizes and detector positions. The planning range uncertainty resulting from the reconstructed RSP is also assessed by comparison with the range of the protons in the analytically simulated phantoms.Results:The results indicate that pCT can intrinsically achieve RSP resolution below 1%, for most examined tissues at beam energies below 300 MeV and for imaging doses around 1 mGy. RSP maps accuracy of less than 0.5 % is observed for most tissue types within the studied dose range (0.2–1.5 mGy). Finally, the uncertainty in the proton range due to the accuracy of the reconstructed RSP map is well below 1%.Conclusion:This work explores the intrinsic performance of pCT as an imaging modality for proton treatment planning. The obtained results show that under ideal conditions, 3D RSP maps can be reconstructed with an accuracy better than 1%. Hence, pCT is a promising candidate for reducing the range uncertainties introduced by the use of X‐ray CT alongside with a semiempirical calibration to RSP.Supported by the DFG Cluster of Excellence Munich‐Centre for Advanced Photonics (MAP)
SU‐E‐J‐155: Automatic Quantitative Decision Making Metric for 4DCT Image Quality
Authors: Kiely J Blanco , Olszanski A , Both S , Low D , White B 
Published: June 2015

Purpose:To develop a quantitative decision making metric for automatically detecting irregular breathing using a large patient population that received phase‐sorted 4DCT.Methods:This study employed two patient cohorts. Cohort#1 contained 256 patients who received a phasesorted 4DCT. Cohort#2 contained 86 patients who received three weekly phase‐sorted 4DCT scans. A previously published technique used a single abdominal surrogate to calculate the ratio of extreme inhalation tidal volume to normal inhalation tidal volume, referred to as the κ metric. Since a single surrogate is standard for phase‐sorted 4DCT in radiation oncology clinical practice, tidal volume was not quantified. Without tidal volume, the absolute κ metric could not be determined, so a relative κ (κrel) metric was defined based on the measured surrogate amplitude instead of tidal volume. Receiver operator characteristic (ROC) curves were used to quantitatively determine the optimal cutoff value (jk) and efficiency cutoff value (τk) of κrel to automatically identify irregular breathing that would reduce the image quality of phase‐sorted 4DCT. Discriminatory accuracy (area under the ROC curve) of κrel was calculated by a trapezoidal numeric integration technique.Results:The discriminatory accuracy of ?rel was found to be 0.746. The key values of jk and tk were calculated to be 1.45 and 1.72 respectively. For values of ?rel such that jk≤κrel≤τk, the decision to reacquire the 4DCT would be at the discretion of the physician. This accounted for only 11.9% of the patients in this study. The magnitude of κrel held consistent over 3 weeks for 73% of the patients in cohort#3.Conclusion:The decision making metric, ?rel, was shown to be an accurate classifier of irregular breathing patients in a large patient population. This work provided an automatic quantitative decision making metric to quickly and accurately assess the extent to which irregular breathing is occurring during phase‐sorted 4DCT.
SU‐E‐J‐156: Velocity‐Based Reference Scan Selection for Motion‐Model Error Reduction of 5DCT
Authors: Yang Liu (Lisa) , O'Connell Dylan , Dou Tai , Thomas David , Lamb James , Low Daniel A. 
Published: June 2015

Purpose:A recently proposed 5DCT protocol uses fast helical CT scans to model lung tissue motion that requires one of the scans to be used as a reference for deformable image registration. We have found that, while the CT scans are acquired using fast helical acquisition, residual motionartifacts remain for scans acquired during mid inspiration or exhalation. Selecting the scan with minimal motion artifacts as the reference scan will improve image registration and model accuracy.Methods:A free‐breathing patient was scanned 25 successive times in alternating directions with a Siemens 64‐slice CT scanner using a low‐mA fast‐helical protocol. Each of the 25 CT scans was successively used as the reference scan with the other 24 images registered to it. Motion‐model parameters were determined using the breathing‐motion model. Voxel specific tissue velocity maps were generated for each of the 25 scan based on the breathing amplitude surrogate and its time derivative. The resulting 24 model error maps were registered to the first CT scan for comparison. The relationships between regional motion‐model error, reference scan motion‐artifacts and tissue‐velocity were analyzed using linear‐regression.Results:Motion‐model errors were linearly correlated with reference scan blurring artifacts and doubling artifacts. The effects of blurring‐artifacts on motion model errors were stronger than doubling artifacts due to their impact on registration accuracy. Selecting the lowest tissue motion velocity scan as the reference scan decreased the regional motion model error by 33.67%±43.12%.Conclusion:Motion‐artifacts, especially blurring artifacts, that exist in the reference image induce motion model errors in 5DCT. A carefully selected reference scan based on the lowest tissue velocities can minimize the regional motion model error.
SU‐E‐J‐159: Analysis of Total Imaging Uncertainty in Respiratory‐Gated Radiotherapy
Authors: Suzuki J , Okuda T , Sakaino S , Yokota N 
Published: June 2015

Purpose:In respiratory‐gated radiotherapy, the gating phase during treatment delivery needs to coincide with the corresponding phase determined during the treatment plan. However, because radiotherapy is performed based on the image obtained for the treatment plan, the time delay, motion artifact, volume effect, and resolution in the images are uncertain. Thus, imaging uncertainty is the most basic factor that affects the localization accuracy. Therefore, these uncertainties should be analyzed. This study aims to analyze the total imaging uncertainty in respiratory‐gated radiotherapy.Methods:Two factors of imaging uncertainties related to respiratory‐gated radiotherapy were analyzed. First, CT image was used to determine the target volume and 4D treatment planning for the Varian Realtime Position Management (RPM) system. Second, an X‐ray image was acquired for image‐guided radiotherapy (IGRT) for the BrainLAB ExacTrac system. These factors were measured using a respiratory gating phantom. The conditions applied during phantom operation were as follows: respiratory wave form, sine curve; respiratory cycle, 4 s; phantom target motion amplitude, 10, 20, and 29 mm (which is maximum phantom longitudinal motion). The target and cylindrical marker implanted in the phantom coverage of the CT images was measured and compared with the theoretically calculated coverage from the phantom motion. The theoretical position of the cylindrical marker implanted in the phantom was compared with that acquired from the X‐ray image. The total imaging uncertainty was analyzed from these two factors.Results:In the CT image, the uncertainty between the target and cylindrical marker's actual coverage and the coverage of CT images was 1.19 mm and 2.50mm, respectively. In the Xray image, the uncertainty was 0.39 mm. The total imaging uncertainty from the two factors was 1.62mm.Conclusion:The total imaging uncertainty in respiratory‐gated radiotherapy was clinically acceptable. However, an internal margin should be added to account for the total imaging uncertainty.
SU‐E‐J‐161: Quality Assurance of 4DCT Process Using ET Gating Phantom System
Authors: Chen H , Chen Z , Nath R , Guo F 
Published: June 2015

Purpose:To develop a robust quality assurance procedure for 4DCT process using ET gating phantom (ET‐GPS), to optimize 4DCT scan protocols, and to investigate practical solutions for patients who have difficulties to be scanned with 4DCT.Methods:ET‐GPS (BrainLab AB) in conjunction with the marker block is used to test the motion tracking of 4DCT imaging and Real‐time Position Management (RPM) system (Varian). Several standard sinusoidal motion profiles as respiratory simulation were used as reference. A maximal motion range of 2.5mm to 16.5mm for horizontal motion (HM) and 6.4mm to 38.0mm for vertical motion (VM), with breathing period time (T) of 3s, 5s, and 7s, were applied to ET‐GPS, respectively. 4DCT images were acquired by LightSpeed 16‐slice CT simulator (GE Medical System), using our general 4DCT chest imaging protocol (cine, 120kVp, 350mA, 0.8s) with scan thicknesses of 1.25mm and 2.5mm, respectively. Maximal motion ranges obtained from 4DCT imaging were analyzed and compared to the references. Furthermore, acquired trajectory profiles from RPM system were played back to the ETGPS, agreement between 2nd acquired trajectories and reference sinusoidal profiles were analyzed quantitatively.Results:Test results of maximal horizontal motion ranges from 4DCT image agree well with the physical measurement (<3%) when the scan thickness is 1.25mm and with T = 5s or 7s. Motion range discrepancy is up to 13.5% for HM when 2.5mm thick is applied. The VM differences are less than 7%. ET‐GPS can reproduce the patient motion profiles very well.Conclusion and discussion:The developed method using ET‐GPS is a feasible and efficient way for quality assurance of 4DCT process. Imaging protocols can be further optimized when agreement is out of the expected. Further 4DCT QA procedure with different HU inserts and customized patient breathing profile will be investigated.
SU‐E‐J‐163: A Biomechanical Lung Model for Respiratory Motion Study
Authors: Liu X , Belcher AH , Grelewicz Z , Wiersma RD 
Published: June 2015

Purpose:This work presents a biomechanical model to investigate the complex respiratory motion for the lung tumor tracking in radiosurgery by computer simulation.Methods:The models include networked massspring‐dampers to describe the tumor motion, different types of surrogate signals, and the force generated by the diaphragm. Each mass‐springdamper has the same mechanical structure and each model can have different numbers of mass‐spring‐dampers. Both linear and nonlinear stiffness parameters were considered, and the damping ratio was tuned in a range so that the tumor motion was over‐damped (no natural tumor oscillation occurs without force from the diaphragm). The simulation was run by using ODE45 (ordinary differential equations by Runge‐Kutta method) in MATLAB, and all time courses of motions and inputs (force) were generated and compared.Results:The curvature of the motion time courses around their peaks was sensitive to the damping ratio. Therefore, the damping ratio can be determined based on the clinical data of a high sampling rate. The peak values of different signals and the time the peaks occurred were compared, and it was found that the diaphragm force had a time lead over the tumor motion, and the lead time (0.1–0.4 seconds) depended on the distance between the tumor and the diaphragm.Conclusion:We reported a model based analysis approach for the spatial and temporal relation between the motion of the lung tumor and the surrogate signals. Due to the phase lead of the diaphragm in comparing with the lung tumor motion, the measurement of diaphragm motion (or its electromyography signal) can be used as a beam gating signal in radiosurgery, and it can also be an additional surrogate signal for better tumor motion tracking.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‐165: Dosimetric Impact of Liver Rotations in Stereotactic Body Radiation Therapy
Authors: Pinnaduwage D , Paulsson A , Sudhyadhom A , Chen J , Chang A , Anwar M , Gottschalk A , Yom S S. , Descovich M 
Published: June 2015

Purpose:Often in liver stereotactic body radiotherapy a single fiducial is implanted near the tumor for image‐guided treatment delivery. In such cases, rotational corrections are calculated based on the spine. This study quantifies rotational differences between the spine and liver, and investigates the corresponding dosimetric impact.Methods:Seven patients with 3 intrahepatic fiducials and 4DCT scans were identified. The planning CT was separately co‐registered with 4 phases of the 4DCT (0%, 50%, 100% inhale and 50% exhale) by 1) rigid registration of the spine, and 2) point‐based registration of the 3 fiducials. Rotation vectors were calculated for each registration. Translational differences in fiducial positions between the 2 registrations methods were investigated. Dosimetric impact due to liver rotations and deformations was assessed using critical structures delineated on the 4DCT phases. For dose comparisons, a single fiducial was translationally aligned following spine alignment to represent what is typically done in the clinic.Results:On average, differences between spine and liver rotations during the 0%, 50%, 100% inhale, and 50% exhale phases were 3.23°, 3.27°, 2.26° and 3.11° (pitch), 3.00°, 2.24°, 3.12° and 1.73° (roll), and 1.57°, 1.98°, 2.09° and 1.36° (yaw), respectively. The maximum difference in rotations was 12°, with differences of >3° seen in 14/28 (pitch), 10/28 (roll), and 6/28 (yaw) cases. Average fiducial displacements of 2.73 (craniocaudal), 1.04 (lateral) and 1.82 mm (vertical) were seen. Evaluating percent dose differences for 5 patients at the peaks of the respiratory cycle, the maximum dose to the duodenum, stomach, bowel and esophagus differed on average by 11.4%, 5.3%, 11.2% and 49.1% between the 2 registration methods.Conclusion:Lack of accounting for liver rotation during treatment might Result in clinically significant dose differences to critical structures. Both rotational and translational deviations should be considered in planning margins when using spine alignment for liver treatments.
SU‐E‐J‐166: Sensitivity of Clinically Relevant Dosimetric Parameters to Contouring Uncertainty During Post Implant Dosimetry of Prostate Permanent Seed Implants
Authors: Mashouf S , Ravi A , Morton G , Song W 
Published: June 2015

Purpose:There is a strong evidence relating post‐implant dosimetry for permanent seed prostate brachytherpy to local control rates. The delineation of the prostate on CT images, however, represents a challenge as it is difficult to confidently identify the prostate borders from soft tissue surrounding it. This study aims at quantifying the sensitivity of clinically relevant dosimetric parameters to prostate contouring uncertainty.Methods:The post‐implant CT images and plans for a cohort of 43 patients, who have received I–125 permanent prostate seed implant in our centre, were exported to MIM Symphony LDR brachytherapy treatment planning system (MIM Software Inc., Cleveland, OH). The prostate contours in post‐implant CT images were expanded/contracted uniformly for margins of ±1.00mm, ±2.00mm, ±3.00mm, ±4.00mm and ±5.00mm (±0.01mm). The values for V100 and D90 were extracted from Dose Volume Histograms for each contour and compared.Results:The mean value of V100 and D90 was obtained as 92.3±8.4% and 108.4±12.3% respectively (Rx=145Gy). V100 was reduced by −3.2±1.5%, −7.2±3.0%, −12.8±4.0%, −19.0±4.8%, − 25.5±5.4% for expanded contours of prostate with margins of +1mm, +2mm, +3mm, +4mm, and +5mm, respectively, while it was increased by 1.6±1.2%, 2.4±2.4%, 2.7±3.2%, 2.9±4.2%, 2.9±5.1% for the contracted contours. D90 was reduced by −6.9±3.5%, −14.5±6.1%, −23.8±7.1%, − 33.6±8.5%, −40.6±8.7% and increased by 4.1±2.6%, 6.1±5.0%, 7.2±5.7%, 8.1±7.3% and 8.1±7.3% for the same set of contours.Conclusion:Systematic expansion errors of more than 1mm may likely render a plan sub‐optimal. Conversely contraction errors may Result in labeling a plan likely as optimal. The use of MRI images to contour the prostate should results in better delineation of prostate organ which increases the predictive value of post‐op plans. Since observers tend to overestimate the prostate volume on CT, compared with MRI, the impact of the contouring uncertainty on V100 and D90 fortunately, has a conservative effect of underestimating the prostate coverage.
SU‐E‐J‐171: The Dosimetric Consequence of a Failed Breath Hold for Left‐Sided DIBH Breast Treatment
Authors: Sintay B , Wentworth S , Vanderstraeten C , Maurer J , Liu H , Hayes L , Wiant D 
Published: June 2015

Purpose:The purpose of this work is to determine the dosimetric consequence of a failed breath hold which may arise out of failure to prompt the patient before initiating treatment or lack of compliance from the patient in taking or maintaining the breath hold. In this context, the patient is assumed to be aligned properly for treatment to the breath hold surface.Methods:Ten left‐sided breast cancer patients were simulated for treatment in the free‐breathing (FB‐CT) and deep‐inspiration breath hold (DIBH‐CT) positions using a bellows device to monitor respiration. The CT scans were fused using a common rigid coordinate system in the underlying couch allowing the analysis of the identical setup position for either FB‐CT or DIBH‐CT. The breast tissue, lumpectomy cavity, heart, and lungs were contoured on each CT. Patients were planned for treatment to 50Gy using a tangent field‐in‐field technique on the DIBH CT scan. The treatment plan was subsequently copied to the free‐breathing scan in the same geometric position and recalculated.Results:No statistically significant dose difference was found for the heart (V30, V20, mean, and maximum) or lumpectomy cavity (mean, maximum, minimum, and V95). However, in two cases, the lumpectomy cavity V95 was 20% less for FB‐CT. The lung V20 decreased by an average of 3.7±1.0% (p=0.004) for FB‐CT. No statistically significant dose difference was found for the mean and maximum breast dose. The minimum breast dose (16.9±3.4 for DIBH) decreased by an average of 11±3.4% (p=0.0001), and the breast V95 (84.7±2.0% for DIBH) decreased by an average of 13.9±7.2% (p=0.003).Conclusion:Our results show that a failed breath hold would not negatively affect the surrounding organs and increased lung sparing. In our study, the lumpectomy cavity remained satisfactorily targeted in 8 out of 10 cases. However, the minimum and V95 breast doses decreased considerably.
SU‐E‐J‐172: Bio‐Physical Effects of Patients Set‐Up Errors According to Whole Breast Irradiation Techniques
Authors: Lee S , Suh T , Park S , Kim M , Park J , Lee M 
Published: June 2015

Purpose:The dose‐related effects of patient setup errors on biophysical indices were evaluated for conventional wedge (CW) and field‐in‐field (FIF) whole breast irradiation techniques.Methods:The treatment plans for 10 patients receiving whole left breast irradiation were retrospectively selected. Radiobiological and physical effects caused by dose variations were evaluated by shifting the isocenters and gantry angles of the treatment plans. Dose‐volume histograms of the planning target volume (PTV), heart, and lungs were generated, and conformity index (CI), homogeneity index (HI), tumor control probability (TCP), and normal tissue complication probability (NTCP) were determined.Results:For “isocenter shift plan” with posterior direction, the D95 of the PTV decreased by approximately 15% and the TCP of the PTV decreased by approximately 50% for the FIF technique and by 40% for the CW; however, the NTCPs of the lungs and heart increased by about 13% and 1%, respectively, for both techniques. Increasing the gantry angle decreased the TCPs of the PTV by 24.4% (CW) and by 34% (FIF). The NTCPs for the two techniques differed by only 3%. In case of CW, the CIs and HIs were much higher than that of the FIF in all cases. It had a significant difference between two techniques (p<0.01). According to our results, however, the FIF had more sensitive response by set up errors rather than CW in bio‐physical aspects.Conclusions:The radiobiological‐based analysis can detect significant dosimetric errors then, can provide a practical patient quality assurance method to guide the radiobiological and physical effects.