Characterization of a Diode Dosimeter for UHDR FLASH Radiotherapy
Mahbubur Rahman, Jakub Kozelka, Jeff Hildreth, Andreas Schonfeld, Austin M. Sloop, M. Ramish Ashraf, Petr Bruza, David J. Gladstone, Brian W. Pogue, William E. … 展开作者
Mahbubur Rahman, Jakub Kozelka, Jeff Hildreth, Andreas Schonfeld, Austin M. Sloop, M. Ramish Ashraf, Petr Bruza, David J. Gladstone, Brian W. Pogue, William E. Simon, Rongxiao Zhang
Purpose: A diode EDGE Detector with a newly designed electrometer has been characterized for use in an UHDR electron beam and demonstrated appropriateness for UHDR FLASH radiotherapy dosimetry.
Methods: Dose linearity, mean dose rate, and dose per pulse dependencies of the EDGE Detector were quantified and compared with dosimeters including a W1 scintillator detector, radiochromic film, and ionization chamber that were irradiated with a 10 MeV UHDR beam. The dose, dose rate and dose per pulse were controlled via an in-house developed scintillation-based feedback mechanism, repetition rate of the linear accelerator, and source-to-surface distance, respectively. Depth-dose profiles and temporal profiles at individual pulse resolution were compared to the film and scintillation measurements, respectively. The radiation-induced change in response sensitivity was quantified via irradiation of ~5kGy.
Results: The EDGE Detector agreed with film measurements in the measured range with varying dose (up to 70 Gy), dose rate (nearly 200 Gy/s), and dose per pulse (up to 0.63 Gy/pulse) on average to within 2%, 5%, and 1%, respectively. The detector also agreed with W1 scintillation detector on average to within 2% for dose per pulse (up to 0.78 Gy/pulse). The EDGE Detector signal was proportional to ion chamber (IC) measured dose, and mean dose rate in the bremsstrahlung tail to within 0.4% and 0.2% respectively. The EDGE Detector measured percent depth dose agreed with film to within 3% and per pulse output agreed with W1 scintillator to within -6% to +5%.
Conclusions: The EDGE Detector demonstrated dose linearity, mean dose rate independence, and dose per pulse independence for UHDR electron beams. It can quantify the beam spatially, and temporally at sub millisecond resolution.
Anatomical motion and deformation pose challenges to the understanding of the delivered dose distribution during radiotherapy treatments. Hence, deformable image registration (DIR) algorithms are increasingly used to map contours and dose distributions from one image set to another. However, the lack of validation tools slows their clinical adoption, despite their commercial availability. This work presents a novel water-equivalent deformable dosimeter that simultaneously measures the dose distribution and tracks deformation vector fields (DVF). The dosimeter in made of an array of 19 scintill…
Review of oxygen measurement and relevance to the mechanisms of FLASH radiotherapy
Thayer School of Engineering at Dartmouth（达特茅斯学院泰耶尔工程学院）；Giesel School of Medicine at Dartmouth（达特茅斯学院吉塞尔医学院）；University of Wisconsin School of Medicine and Public Health（威斯康星大学医学院和公共卫生学院）
Purpose: This is a theoretical simulation study for proof of concept of radiochromic film dosimetry to measure physical and biological doses without plan-based quenching correction for patient-specific quality assurance of carbon-ion radiotherapy. Methods: We took a layer-stacking carbon-ion beam comprised of range-shifted beamlets. The dosimeter response was simulated according to an experimental quenching model. The beam model followed a treatment planning system. The beam was decomposed into finely arranged beamlets with weights estimated by deconvolution of longitudinal dosimeter responses…
We present a first-principles molecular dynamics (MD) simulation and expound upon a mechanism of oxygen depletion hypothesis to explain the mitigation of normal tissue injury observed in ultra-high-dose-rate (UHDR) FLASH radiotherapy. We simulated damage to a segment of DNA (also representing other bio-molecules such as RNA and proteins) in a simulation box filled with H$_2$O and O$_2$ molecules. Attoseconds physical interactions (ionizations, electronic and vibrational excitations) were simulated by using the Monte Carlo track structure code Geant4-DNA. Immediately after ionization, {\it ab i…
Charge Collection Efficiency in Air-Vented Plane-Parallel Ionisation Chambers at Ultra-High Dose Rates: A Self-Consistent Garfield++ Monte Carlo Model Including Space-Charge Effects and Ion Recombination
Université libre de Bruxelles (ULB)（布鲁塞尔自由大学）；Ion Beam Applications SA（离子束应用公司）
Pulse-Width-Specific Phase Space Informed Universal Beam Modeling for UHDR electron LINAC in FLASH-RT
Thayer School of Engineering, Dartmouth College（达特茅斯学院泰勒工程学院）；Dartmouth Cancer Center（达特茅斯癌症中心）；School of Medicine, University of Missouri（密苏里大学医学院）；IntraOp Medical Corporation（IntraOp医疗公司）
Purpose: To verify dose delivery and quality assurance of volumetric modulated arc therapy (VMAT) for head and neck cancer. Method: The Imaging and Radiation Oncology Core Houston (IROC-H) head and neck phantom with thermo- luminescent dosimeters (TLDs) and films, were imaged with computed tomography scan and the reconstructed image was transferred to pinnacle treatment planning system (TPS). On TPS the planning target volume (PTV), secondary target volume (STV) and organ at risk (OAR) were delineated manually and a treatment plan was made. The dose constraints were determined for the concerne…
The widespread diffusion of precision radiotherapy techniques, geared toward the release of larger dose gradients in shorter time frames, is leading to new challenges in dosimetry. Accurate dose measurements are essential to check for beam anomalies and inaccuracies to ensure treatment efficacy and patient safety during radiotherapy. This work describes the main features of a diamond dosimeter coupled to an extremely compact front-end electronics. The detection system was tested under the X-ray pulses generated by a medical LINAC for both the 6 MV and the 18 MV accelerating voltages. Located i…
We present a microscopic mechanism that accounts for the outward burst of "cold" ion species (IS) in a high-energy particle track due to coupling with ''hot" non-ion species (NIS). IS refers to radiolysis products of ionized molecules, whereas NIS refers to non-ionized excitations of molecules in a medium. The interaction is mediated by a quantized field of acoustic phonons, a channel that allows conversion of thermal energy of NIS to kinetic energy of IS, a flow of heat from the outer to the inner core of the track structure. We demonstrate the coexistence of "hot" NIS with "cold" IS in the r…
Characteristics of a 9 MeV electron beam for total skin electron radiotherapy evaluated in comparison to a 6 MeV electron beam
Cancer Care Services, Royal Brisbane and Women’s Hospital（皇家布里斯班和妇女医院癌症护理服务）；School of Chemistry and Physics, Queensland University of Technology（昆士兰科技大学化学与物理学院）；School of Information Technology and Electrical Engineering, University of Queensland（昆士兰大学信息技术与电气工程学院）
Potential pof laser-driven VHEEs towards FLASH radiotherapy: Monte Carlo dosimetric study of single-field pencil beam scanning of a brain tumor
Intense Laser Irradiation Laboratory, CNR-INO（强激光辐照实验室，CNR-INO）；Istituto Nazionale di Fisica Nucleare, Sezione di Pisa（意大利国家核物理研究所，比萨分部）；Clinica S.Rossore（S.Rossore诊所）；CNR-IFC；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
