bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐T‐152: Experimental Validation and Calculation Benchmark for a Commercial Monte Carlo Pencil BeamScanning Proton Therapy Treatment Planning System in Heterogeneous Media
Authors: Lin L , Huang S , Kang M , Ainsley C , Simone C , McDonough J , Solberg T 
Published: July 2016

Purpose:Eclipse AcurosPT 13.7, the first commercial Monte Carlo pencil beam scanning (PBS) proton therapy treatment planning system (TPS), was experimentally validated for an IBA dedicated PBS nozzle in the CIRS 002LFC thoracic phantom.Methods:A two‐stage procedure involving the use of TOPAS 1.3 simulations was performed. First, Geant4‐based TOPAS simulations in this phantom were experimentally validated for single and multi‐spot profiles at several depths for 100, 115, 150, 180, 210 and 225 MeV proton beams, using the combination of a Lynx scintillation detector and a MatriXXPT ionization chamber array. Second, benchmark calculations were performed with both AcurosPT and TOPAS in a phantom identical to the CIRS 002LFC, with the exception that the CIRS bone/mediastinum/lung tissues were replaced with similar tissues that are predefined in AcurosPT (a limitation of this system which necessitates the two stage procedure).Results:Spot sigmas measured in tissue were in agreement within 0.2 mm of TOPAS simulation for all six energies, while AcurosPT was consistently found to have larger spot sigma (<0.7 mm) than TOPAS. Using absolute dose calibration by MatriXXPT, the agreements between profiles measurements and TOPAS simulation, and calculation benchmarks are over 97% except near the end of range using 2 mm/2% gamma criteria. Overdosing and underdosing were observed at the low and high density side of tissue interfaces, respectively, and these increased with increasing depth and decreasing energy. Near the mediastinum/lung interface, the magnitude can exceed 5 mm/10%. Furthermore, we observed >5% quenching effect in the conversion of Lynx measurements to dose.Conclusion:We recommend the use of an ionization chamber array in combination with the scintillation detector to measure absolute dose and relative PBS spot characteristics. We also recommend the use of an independent Monte Carlo calculation benchmark for the commissioning of a commercial TPS.Partially supported by Varian Medical System under the master agreement between Varian and University of pennsylvania
SU‐F‐T‐169: A Periodic Quality Assurance Program for a Spot‐Scanning Proton Treatment Facility
Authors: Mundy D , Tryggestad E , Beltran C , Furutani K , Gilson G , Ito S , Johnson J , Kruse J , Remmes N , Tasson A , Whitaker T , Herman M 
Published: July 2016

Purpose:To develop daily and monthly quality assurance (QA) programs in support of a new spot‐scanning proton treatment facility using a combination of commercial and custom equipment and software. Emphasis was placed on efficiency and evaluation of key quality parameters.Methods:The daily QA program was developed to test output, spot size and position, proton beam energy, and image guidance using the Sun Nuclear Corporation rf‐DQA™3 device and Atlas QA software. The program utilizes standard Atlas linear accelerator tests repurposed for proton measurements and a custom jig for indexing the device to the treatment couch. The monthly QA program was designed to test mechanical performance, image quality, radiation quality, isocenter coincidence, and safety features. Many of these tests are similar to linear accelerator QA counterparts, but many require customized test design and equipment. Coincidence of imaging, laser marker, mechanical, and radiation isocenters, for instance, is verified using a custom film‐based device devised and manufactured at our facility. Proton spot size and position as a function of energy are verified using a custom spot pattern incident on film and analysis software developed in‐house. More details concerning the equipment and software developed for monthly QA are included in the supporting document. Thresholds for daily and monthly tests were established via perturbation analysis, early experience, and/or proton system specifications and associated acceptance test results.Results:The periodic QA program described here has been in effect for approximately 9 months and has proven efficient and sensitive to sub‐clinical variations in treatment delivery characteristics.Conclusion:Tools and professional guidelines for periodic proton system QA are not as well developed as their photon and electron counterparts. The program described here efficiently evaluates key quality parameters and, while specific to the needs of our facility, could be readily adapted to other proton centers.
SU‐F‐T‐171: Manufacturing Cost Effective Heterogeneous Phantoms for Use in Proton Therapy
Authors: Pruett J , Chen Y , Ahmad S , Johnson D 
Published: July 2016

Purpose:To study the feasibility of 3D printing cost effective heterogeneous phantoms for use in proton therapy treatment planning quality assurance.Methods:A desktop 3D printer was utilized to create a series of 2 cm × 2 cm × 4 cm PLA plastic blocks of varying fill materials and hexagonal fill pattern. The blocks were than tested when filled with air, polyurethane foam, paraffin, silicone, and caulk of calcium carbonate – acrylic polymer blend. The blocks were evaluated with a “GE Lightspeed” 16 slice CT scanner and average CT# of the materials’ centers evaluated. Blocks were then placed into a custom aperture fitted to a Mevion Proton system to determine the relative stopping power of each. Scans were performed in water tank with Marcus type parallel plate chamber under a beam with a range of 15 cm and modulation of 2 cm. Shifts in range occurring relative to the 80% distal edge of the open SOBP were evaluated.Results:The CT#s of the blocks were plotted against their measured relative stopping power. This curve was compared to that which is in clinical use. While the trend agrees generally, specific differences between the relative stopping powers were as great as 10%.Conclusion:We have demonstrated that it is possible to utilize different cost effective materials in the manufacturing of phantoms for use in proton therapy. While different materials may provide better agreement to established calibration curves, a custom curve specific to the materials used may be utilized to accurately predict proton treatment dose distributions.
SU‐F‐T‐174: Patient‐Specific Point Dose Measurement Using Fiber Optic Radiation Sensor Using Cerenkov Radiation for Proton Therapeutic Beam
Authors: Son J , Kim M , Yoon M , Shin D 
Published: July 2016

Purpose:A fiber‐optic radiation sensor using Cerenkov radiation (FOCR) has been widely studied for use as a dosimeter for proton therapeutic beam. We developed the FOCR, and it applied to patient‐specific point dose measurement in order to evaluate the effectiveness of the FOCR system for proton therapy QA.Methods:Calibration of FOCR was performed with an ionization chamber whose absolute doses were determined according to the IAEA TRS‐398 protocol. To determine the calibration curve, the FOCR was irradiated perpendicularly to the proton beam at the 13 dose levels steps. We selected five actual patient treatment plans performed at proton therapy center and compared the resulting FOCR measurements with the ionization chamber measurements.Results:The Cerenkov light yield of the FOCR increases linearly with as the dose measured using the ionization chamber increases from 0 cGy to 500 cGy. The results indicate that the fitting curve is linear, suggesting that dose measurement based on the light yield of the FOCR is possible. The results of proton radiation dose QA performed using the FOCR for 10 proton fields and five patients are good agreement with an ionization chamber.Conclusion:We carried out the patient QA using the FOCR for proton therapeutic beam and evaluated the effectiveness of the FOCR as a proton therapy QA tool. Our results indicate that the FOCR is suitable for use in patient QA of clinical proton beams.
SU‐F‐T‐175: Absorbed Dose Measurement Using Radiophotoluminescent Glass Dosimeter in Therapeutic Proton Beam
Authors: Chang W , Koba Y , Katayose T , Hariu M , Yasui K , Saitoh H 
Published: July 2016

Purpose:To measure the absorbed dose to water Dw in therapeutic proton beam with radiophotoluminescent glass dosimeter (RGD), a methodology was proposed. In this methodology, the correction factor for the LET dependence of radiophotoluminescent (RPL) efficiency and the variation of mass stopping power ratio of water to RGD (SPRw, RGD) were adopted. The feasibility of proposed method was evaluated in this report.Methods:The calibration coefficient in terms of Dw for RGDs (GD‐302M, Asahi Techno Glass) was obtained using 60Co beam. The SPRw, RGD was calculated by Monte Carlo simulation toolkit Geant4. The LET dependence of RPL efficiency was investigated experimentally by using a 70 MeV proton beam at National Institute of Radiological Sciences. For clinical usage, the residual range Rres was used as a quality index to determine the correction factor for RPL efficiency. The proposed method was evaluated by measuring Dw at difference depth in the 200 MeV proton beam.Results:For both modulated and non‐modulated proton beam, the SPRw, RGD increases more than 3 % where Rres are less than 1 cm. RPL efficiency decreases with increasing LET and it reaches 0.6 at LET of 10 keV µm−1. Dw measured by RGD (Dw, RGD) shows good agreement with that measured by ionization chamber (Dw, IC) and the relative difference between Dw, RGD and Dw, IC are within 3 % where Rres is larger than 1 cm.Conclusion:In this work, a methodology for using RGD in proton dosimetry was proposed and the SPRw, RGD and the LET dependence of RPL efficiency in therapeutic proton beam was investigated. The results revealed that the proposed method is useful for RGD in the dosimetry of proton beams.
SU‐F‐T‐178: Optimized Design of a Diamond Detector Specifically Dedicated to the Dose Distribution Measurements in Clinical Proton Pencil Beams
Authors: Moignier C , Tromson D , Marsolat F , De Marzi L , Pomorski M , Agelou M , Hernandez J Garcia , Lazaro D , Mazal A 
Published: July 2016

Purpose:In proton‐therapy, pencil beam scanning (PBS) dosimetry presents a real challenge due to the small size of the beam (about 3 to 8 mm in FWHM), the pulsed high dose rate (up to 100 Gy/s) and the proton energy variation (about 30 MeV to 250 MeV). In the framework of French INSERM DEDIPRO project, a specifically dedicated single crystal diamond dosimeter (SCDDo) was developed with the objective of obtaining accurate measurements of the dose distribution in PBS modality.Methods:Monte Carlo simulations with MCNPX were performed. A small proton beam of 5 mm in FWHM was simulated as well as diamond devices with various size, thickness and holder composition. The calculated doses‐to‐diamond were compared with the doses‐to‐water in order to reduce the perturbation effects. Monte‐Carlo simulations lead to an optimized SCDDo design for small proton beams dosimetry. Following the optimized design, SCDDos were mounted in water‐equivalent holders with electrical connection adapted to standard electrometer. First, SCDDos performances (stability, repeatability, signal‐to‐background ratio…) were evaluated with conventional photon beams. Then, characterizations (dose linearity, dose rate dependence…) with wide proton beams were performed at proton‐therapy center (IC‐CPO) from Curie Institute (France) with the passive proton delivery technique, in order to confirm dosimetric requirements. Finally, depth‐dose distributions were measured in a water tank, for native and modulated Bragg Peaks with the collimator of 12 cm, and compared to a commercial PPC05 parallel‐plate ionization chamber reference detector. Lateral‐dose profiles were also measured with the collimator of 5 mm, and compared to a commercial SFD diode.Results:The results show that SCDDo design does not disturb the dose distributions.Conclusion:The experimental dose distributions with the SCDDo are in good agreement with the commercial detectors and no energy dependence was observed with this device configuration.
SU‐F‐T‐179: Fast and Accurate Profile Acquisition for Proton Beam Using Multi‐Ion Chamber Arrays
Authors: Wang X , Mo X , Zou J , Chen T , Yue N , Zhang M 
Published: July 2016

Purpose:Proton beam profile measurement is more time‐consuming than photon beam. Due to the energy modulation during proton delivery, chambers have to move step‐by‐step instead of continuously. Multi‐ion chamber arrays are appealing to this task since multiple measurements can be performed at once. However, their utilization suffers from sparse spatial resolution and potential intrinsic volume‐averaging effect of the disk‐shaped ion chambers. We proposed an approach to measure proton beam profiles accurately and efficiently.Methods:Mevion S250 proton system and IBA Matrixx ion chamber arrays were used in this study. Matrixx has interchamber distance of 7.62 mm, and chamber diameter of 4.5 mm. We measured the same beam profile by moving the Matrixx seven times with 1 mm each time along y axis. All 7 measurements were superimposed to get a “finer” profile with 1 mm spatial resolution. Coarser resolution profiles of 2 mm and 3 mm were also generated by using subsets of measurements. Those profiles were compared to the TPS calculated beam profile. Gamma analysis was performed for 2D dose maps to evaluate the difference to TPS dose plane.Results:Preliminary results showed a large discrepancy between the TPS calculated profile and the single measurement profile with 7.6 mm resolution. A good match could be achieved when the resolution reduced to 3 mm by adding one extra measurement. Gamma analysis for 2D dose map of a 10×10 field showed a passing rate (γ ≤ 1) of 90.6% using a 3% and 3mm criterion for single measurement, which increased to 92.3% for 2‐measurement superimposition, and slightly further increased to 92.9% for 7‐measurement superimposition.Conclusion:The results indicated that 2 measurements shifted by 3mm using Matrixx generated a smooth proton beam profile with good matching to Eclipse beam profile. We suggest using this 2‐measurement approach in clinic for double scattering proton beam profile measurement.
SU‐F‐T‐195: Systematic Constraining of Contralateral Parotid Gland Led to Improved Dosimetric Outcomes for Multi‐Field Optimization with Scanning Beam Proton Therapy: Promising Results From a Pilot Study in Patients with Base of Tongue Carcinoma
Authors: Wu R , Crowford C , Georges R , Liu A , Amin M , Sio T , Gunn B , Poenisch F , Palmer M , Gillin M , Frank S , Zhu X 
Published: July 2016

Purpose:Treatment planning for Intensity Modulated Proton Therapy (IMPT) for head and neck cancer is time‐consuming due to the large number of organs‐at‐risk (OAR) to be considered. As there are many competing objectives and also wide range of acceptable OAR constraints, the final approved plan may not be most optimal for the given structures. We evaluated the dose reduction to the contralateral parotid by implementing standardized constraints during optimization for scanning beam proton therapy planning.Methods:Twenty‐four (24) consecutive patients previously treated for base of tongue carcinoma were retrospectively selected. The doses were 70Gy, 63Gy and 57Gy (SIB in 33 fractions) for high‐, intermediate‐, and standard‐risk clinical target volumes (CTV), respectively; the treatment included bilateral neck. Scanning beams using MFO with standardized bilateral anterior oblique and PA fields were applied. New plans where then developed and optimized by employing additional contralateral parotid constraints at multiple defined dose levels. Using a step‐wise iterative process, the volume‐based constraints at each level were then further reduced until known target coverages were compromised. The newly developed plans were then compared to the original clinically approved plans using paired student t‐testing.Results:All 24 newly optimized treatment plans maintained initial plan quality as compared to the approved plans, and the 98% prescription dose coverage to the CTV's were not compromised. Representative DVH comparison is shown in FIGURE 1. The contralateral parotid doses were reduced at all levels of interest when systematic constraints were applied to V10, V20, V30 and V40Gy (All P<0.0001; TABLE 1). Overall, the mean contralateral parotid doses were reduced by 2.26 Gy on average, a ∼13% relative improvement.Conclusion:Applying systematic and volume‐based contralateral parotid constraints for IMPT planning significantly reduced the dose at all dosimetric levels for patients with base of tongue cancer.
SU‐F‐T‐197: Investigating Optimal Oblique‐Beam Arrangement for Bilateral Metallic Prosthesis Prostate Cancer in Pencil Beam Scanning Proton Therapy
Authors: Rana S , Zheng Y , Cheng C , Singh H , Twyford T , Tesfamicael B , Park S 
Published: July 2016

Purpose:The main purpose of this study is to investigate the optimum oblique‐beam arrangement for bilateral metallic prosthesis prostate cancer treatment in pencil beam scanning (PBS) proton therapy.Methods:A computed tomography dataset of bilateral metallic prosthesis prostate cancer case was selected for this retrospective study. A total of four beams (rightanterior‐ oblique [RAO], left‐anterior‐oblique [LAO], left‐posterior‐oblique [LPO], and right‐posterior‐oblique [RPO]) were selected for treatment planning. PBS plans were generated using multi‐field‐optimization technique for a total dose of 79.2 Gy[RBE] to be delivered in 44 fractions. Specifically, five different PBS plans were generated based on 2.5% ± 2 mm range uncertainty using five different beam arrangements (i)LAO+RAO+LPO+RPO, (ii)LAO+RAO, (iii)LPO+RPO, (iv)RAO+LPO, and (v)LAO+RPO. Each PBS plan was optimized by applying identical dose‐volume constraints to the PTV, rectum, and bladder. Treatment plans were then compared based on the dose‐volume histograms results.Results:The PTV coverage was found to be greater than 99% in all five plans. The homogeneity index (HI) was found to be almost identical (range, 0.03–0.04). The PTV mean dose was found to be comparable (range, 81.0–81.1 Gy[RBE]). For the rectum, the lowest mean dose (8.0 Gy[RBE]) and highest mean dose (31.1 Gy[RBE]) were found in RAO+LAO plan and LPO+RPO plan, respectively. LAO+RAO plan produced the most favorable dosimetric results of the rectum in the medium‐dose region (V50) and high‐dose region (V70). For the bladder, the lowest (5.0 Gy[RBE]) and highest mean dose (10.3 Gy[RBE]) were found in LPO+RPO plan and RAO+LAO plan, respectively. Other dosimetric results (V50 and V70) of the bladder were slightly better in LPO+RPO plan than in other plans.Conclusion:Dosimetric findings from this study suggest that two anterior‐oblique proton beams arrangement (LAO+RAO) is a more favorable option with the possibility of reducing rectal dose significantly while maintaining comparable target coverage and acceptable bladder dose.
SU‐F‐T‐198: Dosimetric Comparison of Carbon and Proton Radiotherapy for Recurrent Nasopharynx Carcinoma
Authors: Sheng Y , Zhao J , Wang W , Lin L , Liu X , Shahnazi K 
Published: July 2016

Purpose:Various radiotherapy planning methods for locally recurrent nasopharynx carcinoma (R‐NPC) have been proposed. The purpose of this study was to compare carbon and proton therapy for the treatment of R‐NPC in terms of dose coverage for target volume and sparing for organs at risk (OARs).Methods:Six patients who were suffering from R‐NPC and treated using carbon therapy were selected for this study. Treatment plans with a total dose of 57.5Gy (RBE) in 23 fractions were made using SIEMENS Syngo V11. An intensity‐modulated radiotherapy optimization method was chosen for carbon plans (IMCT) while for proton plans both intensity‐modulated radiotherapy (IMPT) and single beam optimization (proton‐SBO) methods were chosen. Dose distributions, dose volume parameters, and selected dosimetric indices for target volumes and OARs were compared for all treatment plans.Results:All plans provided comparable PTV coverage. The volume covered by 95% of the prescribed dose was comparable for all three plans. The average values were 96.11%, 96.24% and 96.11% for IMCT, IMPT, and proton‐SBO respectively. A significant reduction of the 80% and 50% dose volumes were observed for the IMCT plans compared to the IMPT and proton‐SBO plans. Critical organs lateral to the target such as brain stem and spinal cord were better spared by IMPT than by proton‐SBO, while IMCT spared those organs best. For organs in the beam path, such as parotid glands, the mean dose results were similar for all three plans.Conclusion:Carbon plans yielded better dose conformity than proton plans. They provided similar or better target coverage while significantly lowering the dose for normal tissues. Dose sparing for critical organs in IMPT plans was better than proton‐SBO, however, IMPT is known to be more sensitive to range uncertainties. For proton plans it is essential to find a balance between the two optimization methods.
SU‐F‐T‐209: Multicriteria Optimization Algorithm for Intensity Modulated Radiation Therapy Using Pencil Proton Beam Scanning
Authors: Beltran C , Kamal H 
Published: July 2016

Purpose:To provide a multicriteria optimization algorithm for intensity modulated radiation therapy using pencil proton beam scanning.Methods:Intensity modulated radiation therapy using pencil proton beam scanning requires efficient optimization algorithms to overcome the uncertainties in the Bragg peaks locations. This work is focused on optimization algorithms that are based on Monte Carlo simulation of the treatment planning and use the weights and the dose volume histogram (DVH) control points to steer toward desired plans. The proton beam treatment planning process based on single objective optimization (representing a weighted sum of multiple objectives) usually leads to time‐consuming iterations involving treatment planning team members. We proved a time efficient multicriteria optimization algorithm that is developed to run on NVIDIA GPU (Graphical Processing Units) cluster. The multicriteria optimization algorithm running time benefits from up‐sampling of the CT voxel size of the calculations without loss of fidelity.Results:We will present preliminary results of Multicriteria optimization for intensity modulated proton therapy based on DVH control points. The results will show optimization results of a phantom case and a brain tumor case.Conclusion:The multicriteria optimization of the intensity modulated radiation therapy using pencil proton beam scanning provides a novel tool for treatment planning.Work support by a grant from Varian Inc.