Publications by authors named "Joshua B Stoker"
Article Synopsis
- Traditional bolus materials in radiotherapy help optimize dose delivery to superficial targets, but they fall short for specialized cases like cavity filling, prompting the exploration of 3D printing as a solution.
- The study aims to implement a comprehensive 3D printed bolus solution using failure modes and effects analysis (FMEA) to enhance workflow and quality assurance in a clinical setting.
- The results showed a detailed workflow with numerous steps and potential failure modes, emphasizing the importance of early collaboration between physics and dosimetry to ensure safe and effective use of the new silicone bolus designs.
. To enhance an in-house graphic-processing-unit accelerated virtual particle (VP)-based Monte Carlo (MC) proton dose engine (VPMC) to model aperture blocks in both dose calculation and optimization for pencil beam scanning proton therapy (PBSPT)-based stereotactic radiosurgery (SRS)..
View Article and Find Full Text PDFArticle Synopsis
- The study aims to improve a GPU-accelerated Monte Carlo proton dose engine to effectively model aperture blocks in proton therapy.
- A new module for simulating virtual particles through patient-specific aperture blocks was developed and validated against an established Monte Carlo code, achieving high accuracy in dose calculations.
- The results showed a significant reduction in calculation time, allowing for efficient optimization of treatment plans while meeting all dose constraints for patients.
Article Synopsis
- - The study aims to create an online Monte Carlo-based workflow for adaptive radiation therapy using GPU acceleration to better manage anatomical changes in patients receiving proton therapy with pencil beam scanning.
- - The workflow includes four key steps: deformable image registration to align CT scans, dose calculation on updated scans, plan reoptimization based on verification dose, and patient-specific quality assurance before and after treatment.
- - The evaluation methods for the workflow's effectiveness include various similarity metrics for contour accuracy and 3D gamma analysis to verify dose accuracy, tested on three patients across different disease sites.
Purpose: The multiple energy extraction (MEE) delivery technique for synchrotron-based proton delivery systems reduces beam delivery time by decelerating the beam multiple times during one accelerator spill, but this might cause additional plan quality degradation due to intrafractional motion. We seek to determine whether MEE causes significantly different plan quality degradation compared to single energy extraction (SEE) for lung cancer treatments due to the interplay effect.
Methods: Ten lung cancer patients treated with IMPT at our institution were nonrandomly sampled based on a representative range of tumor motion amplitudes, tumor volumes, and respiratory periods.
Purpose: Patient-Specific Quality Assurance (PSQA) measurement analysis depends on generating metrics representative of calculation and measurement agreement. Considering the heightened capability of discrete spot scanning protons to modulate individual dose voxels, a dose plane comparison approach that maintained all of the capabilities of the well-established γ test, but that also provided a more intuitive error parameterization, was desired.
Methods: Analysis was performed for 300 dose planes compared by searching all calculated points within a fixed radius around each measured pixel to determine the dose deviation.
Purpose: To describe and validate the dose calculation algorithm of an independent second-dose check software for spot scanning proton delivery systems with full width at half maximum between 5 and 14 mm and with a negligible spray component.
Methods: The analytical dose engine of our independent second-dose check software employs an altered pencil beam algorithm with 3 lateral Gaussian components. It was commissioned using Geant4 and validated by comparison to point dose measurements at several depths within spread-out Bragg peaks of varying ranges, modulations, and field sizes.
Purpose: At our institution, all proton patient plans undergo patient-specific quality assurance (PSQA) prior to treatment delivery. For intensity-modulated proton beam therapy, quality assurance is complex and time consuming, and it may involve multiple measurements per field. We reviewed our PSQA workflow and identified the steps that could be automated and developed solutions to improve efficiency.
View Article and Find Full Text PDFPurpose: Multiple energy extraction (MEE) is a technology that was recently introduced by Hitachi for its spot-scanning proton treatment system, which allows multiple energies to be delivered in a single synchrotron spill. The purpose of this paper is to investigate how much beam delivery time (BDT) can be reduced with MEE compared with single energy extraction (SEE), in which one energy is delivered per spill.
Methods And Materials: A recently developed model based on BDT measurements of our synchrotron's delivery performance was used to compute BDT.
Purpose: The aim of this work was to develop an efficient daily quality assurance (QA) program with strict tolerance levels for pencil beam scanning (PBS) proton radiotherapy featuring simultaneous dosimetric testing on a single, nonuniform field.
Methods: A nonuniform field measuring beam output, proton range, and spot position was designed for delivery onto a Sun Nuclear Daily-QA 3 device. A custom acrylic block permitted simultaneous measurement of low- and high-energy proton ranges in addition to beam output.
Monte Carlo (MC) simulation has been used to generate commissioning data for the beam modeling of treatment planning system (TPS). We have developed a method called radial projection (RP) for postprocessing of MC-simulation-generated data. We used the RP method to reduce the statistical uncertainty of the lateral profile of proton pencil beams with axial symmetry.
View Article and Find Full Text PDFIntroduction: The range shifter (RS) is used to treat shallow tumors for a proton pencil beam scanning system (PBS). Adding RS certainly complicates the commissioning of the treatment planning system (TPS) because the spot sizes are significantly enlarged with RS. In this work, we present an efficient method to configure a commercial TPS for a PBS system with a fixed RS.
View Article and Find Full Text PDFPurpose: The purpose of this study was to compare the impact of uncertainties and interplay on 3-dimensional (3D) and 4D robustly optimized intensity modulated proton therapy (IMPT) plans for lung cancer in an exploratory methodology study.
Methods And Materials: IMPT plans were created for 11 nonrandomly selected non-small cell lung cancer (NSCLC) cases: 3D robustly optimized plans on average CTs with internal gross tumor volume density overridden to irradiate internal target volume, and 4D robustly optimized plans on 4D computed tomography (CT) to irradiate clinical target volume (CTV). Regular fractionation (66 Gy [relative biological effectiveness; RBE] in 33 fractions) was considered.
Purpose: To quantitatively investigate the effect of range shifter materials on single-spot characteristics of a proton pencil beam.
Methods: An analytic approximation for multiple Coulomb scattering ("differential Moliere" formula) was adopted to calculate spot sizes of proton spot scanning beams impinging on a range shifter. The calculations cover a range of delivery parameters: six range shifter materials (acrylonitrile butadiene styrene, Lexan, Lucite, polyethylene, polystyrene, and wax) and water as reference material, proton beam energies ranging from 75 to 200 MeV, range shifter thicknesses of 4.
Purpose: To compare field junction robustness and sparing of organs at risk (OARs) during craniospinal irradiation (CSI) using intensity modulated proton therapy (IMPT) to conventional passively scattered proton therapy (PSPT).
Methods And Materials: Ten patients, 5 adult and 5 pediatric patients, previously treated with PSPT-based CSI were selected for comparison. Anterior oblique cranial fields, using a superior couch rotation, and posterior spinal fields were used for IMPT planning.