TOPAS Monte Carlo simulation for double scattering proton therapy and dosimetric evaluation

Proton therapy has become increasingly accepted around the world. According to the latest PTCOG statistics, there are currently 77 proton therapy centers in operation worldwide, with 44 new facilities under construction and 20 facilities in plan stage [1]. By the end of 2017, more than 170,000 patients have been treated with proton therapy [2]. Based on how 3D dose distributions are produced, proton therapy delivery methods can be divided as passive scattering, uniform scanning, and pencil beam scanning techniques [3 –5].
Source: Physica Medica: European Journal of Medical Physics - Category: General Medicine Authors: Tags: Original paper Source Type: research

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Abstract OBJECTIVES: To assess the radiation-induced optic neuropathy (RION) prevalence, following high dose pencil beam scanning proton therapy (PBS PT) to skull base and head and neck (H&N) tumours. METHODS: Between 1999 and Between , 2014 and Between , 216 adult patients, median age 47 years (range, 18-77), were treated with PBS PT for skull base or H&N malignancies, delivering ≥45 GyRBE to the optic nerve(s) (ON) and/or optic chiasma (OC). The median administered dose to the planning target volume (PTV) was 74.0 GyRBE (range, 54.0-77.4). The median follow-up was 5.3 years (range, 0.8-15.9). RESULT...
Source: The British Journal of Radiology - Category: Radiology Authors: Tags: Br J Radiol Source Type: research
Abstract The step-and-shoot method of pencil beam scanning delivers the dose on a three-dimensional grid in the target volume, with one dimension defined by the proton energy. While the dose per pencil beam may vary substantially within an iso-energy layer, the beam current typically remains constant. In this static operation mode, the inherent latency of the beam switch-off mechanism results in a lower limit for the deliverable spot dose, which may prevent the application of some of the low-weighted spots prescribed by the treatment planning system. To overcome this limitation, we introduced dynamic beam current ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
Abstract Positron emission tomography (PET) has been extensively studied and clinically investigated for dose verification in proton therapy. However, the production distributions of positron emitters are not proportional to the dose distribution. Thus, direct dose evaluation is limited when using the conventional PET-based approach. We propose a method for estimating the dose distribution from the positron emitter distributions using the maximum likelihood (ML) expectation maximization (EM) algorithm combined with filtering. In experiments to verify the effectiveness of the proposed method, mono-energetic and spr...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
Our institution utilizes both biologic and standard dose models in spot scanning proton treatment planning. This analysis examines the rates of post-treatment radiologic change as detected on post-treatment MRI scans, and toxicities for pediatric brain tumor patients treated during the first year of our institution ’s experience. Our novel biologic dose model was found to demonstrate greater volumetric overlap with the post-treatment radiologic changes, than the standard dose model.
Source: International Journal of Radiation Oncology * Biology * Physics - Category: Radiology Authors: Source Type: research
CONCLUSION: We have carried out an extensive measurement of H*(10) under different conditions. The shielding thickness of our PT facility is adequate to limit the dose to occupational worker and general public within the permissible stipulated limit. The data reported here can bridge the knowledge gap in ambient dose around PT facility and can also be used as a reference for any new and existing proton facility for inter comparison and validation. ADVANCES IN KNOWLEDGE: First extensive investigation of neutron and photon H*(10) around PT facility and can bridge the knowledge gap on ambient dose. PMID: 31287739 [P...
Source: The British Journal of Radiology - Category: Radiology Authors: Tags: Br J Radiol Source Type: research
o T, Khan R Abstract Radiochromic films have been widely studied for clinical dosimetry in conventional external beam radiation therapy. With an increase in practice of proton therapy, such films are being conveniently used; however, their spectroscopic characterization for this modality is lacking. This work investigated the response of the EBT3 radiochromic films irradiated in a Mevion S250™ clinical proton beam. Dose, dose rate, inter-batch, sensitivity, and linear energy transfer (LET) dependencies of the films were studied. Pieces of the radiochromic films from different batches were irradiated using a ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
We describe the iterative process we have applied to design the magnets and the beam transport, for which we have used different codes. <i>COSY Infinity</i> and <i>OPAL</i> have been used to design the beam transport optics and to track the particles in the magnetic fields, which are produced by the magnets designed in <i>Opera</i>. With beam optics calculations we have derived an optimal achromatic beam transport with the large momentum acceptance of the proton pencil beam and we show the agreement with particle tracking calculations in th...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
Conclusions: Image analysis revealed a slight advantage of 2D Unets compared to 3D Unets. Similar dose calculation performance was reached for the 2D and 3D network. PMID: 31271093 [PubMed - as supplied by publisher]
Source: Acta Oncologica - Category: Cancer & Oncology Authors: Tags: Acta Oncol Source Type: research
Würl M Abstract Background: Precision small animal radiotherapy research is a young emerging field aiming to provide new experimental insights into tumor and normal tissue models in different microenvironments, to unravel complex mechanisms of radiation damage in target and non-target tissues and assess efficacy of novel therapeutic strategies. For photon therapy, modern small animal radiotherapy research platforms have been developed over the last years and are meanwhile commercially available. Conversely, for proton therapy, which holds potential for an even superior outcome than photon therapy, no commerci...
Source: Acta Oncologica - Category: Cancer & Oncology Authors: Tags: Acta Oncol Source Type: research
Conclusion: The automated prior-plan adaptation method can successfully adapt for the large day-to-day variations observed in cervical cancer patients. PMID: 31271076 [PubMed - as supplied by publisher]
Source: Acta Oncologica - Category: Cancer & Oncology Authors: Tags: Acta Oncol Source Type: research
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