Feasibility of MR-only proton dose calculations for prostate cancer radiotherapy using a commercial pseudo-CT generation method.

Feasibility of MR-only proton dose calculations for prostate cancer radiotherapy using a commercial pseudo-CT generation method. Phys Med Biol. 2017 Oct 27;: Authors: Maspero M, Van den Berg CAT, Landry G, Belka C, Parodi K, Seevinck PR, Raaymakers BW, Kurz C Abstract A magnetic resonance (MR)-only radiotherapy workflow can reduce cost, radiation exposure and uncertainties introduced by CT-MRI registration. A crucial prerequisite is generating the so called pseudo-CT (pCT) images for accurate dose calculation and planning. Many pCT generation methods have been proposed in the scope of photon radiotherapy. This work aims at verifying for the first time whether a commercially available photon-oriented pCT generation method can be employed for accurate intensity-modulated proton therapy (IMPT) dose calculation. A retrospective study was conducted on ten prostate cancer patients. For pCT generation from MR images, a commercial solution for creating bulk-assigned pCTs, called MR for Attenuation Correction (MRCAT), was employed. The assigned pseudo-Hounsfield Unit (HU) values were adapted to yield an increased agreement to the reference CT in terms of proton range. Internal air cavities were copied from the CT to minimise inter-scan differences. CT- and MRCAT-based dose calculations for opposing beam IMPT plans were compared by gamma analysis and evaluation of clinically relevant target and organ at risk dose volume histogram (DVH) parameters. The proton ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research

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In this study, the impact of realistic inline MRI fringe field on IMPT plan delivery is investigated for a water phantom, liver tumor and prostate cancer differing in target volume, shape, and field configuration using Monte Carlo simulations. A method to correct for the shift of the beam spot positions in the presence of the inline magnetic field is presented. Results show that when not accounting for the effect of the magnetic field on the pencil beam delivery, the spot positions are substantially shifted and the quality of delivered plans is significantly deteriorated leading to dose inhomogeneities and creation of hot ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
ConclusionsProton beam radiotherapy for prostate cancer is feasible with a low rate of acute toxicity and promising late toxicity and effectivity.
Source: Journal of Medical Imaging and Radiation Oncology - Category: Radiology Authors: Tags: Radiation Oncology —Original Article Source Type: research
Conditions:   Low Risk Prostate Cancer;   Intermediate Risk Prostate Cancer Interventions:   Other: EPIC questionnaire;   Radiation: kV x-ray images;   Radiation: Conebeam CT Sponsor:   EBG MedAustron GmbH Recruiting
Source: ClinicalTrials.gov - Category: Research Source Type: clinical trials
Abstract PURPOSE: To report acute and late genitourinary (GU) and gastrointestinal (GI) toxicities associated with post-prostatectomy proton therapy (PT). METHODS: The first 100 consecutive patients from 2010 to 2016 were retrospectively assessed. Baseline characteristics, prospectively graded CTCAE v4.0 toxicities, and patient-reported outcomes were reported. Late outcomes were reported for 79 patients with 3 months minimum follow up. Toxicity-free survival Kaplan-Meier curves were estimated. Logistic regression assessed associations between toxicities and clinical and treatment characteristics (p 
Source: Acta Oncologica - Category: Cancer & Oncology Authors: Tags: Acta Oncol Source Type: research
This study's purpose is to develop and evaluate an automated method for adaptation of IMPT plans in near real-time to the anatomy of the day. We developed an automated treatment plan adaptation method using (1) a restoration of spot positions (Bragg peaks) by adapting the energies to the new water equivalent path lengths; and (2) a spot addition to fully cover the target of the day, followed by a fast Reference Point Method optimization of the spot weights resulting in a Pareto optimal plan for the daily anatomy. The method was developed and evaluated using 8-10 repeat CT scans of 11 prostate cancer patients, prescrib...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
Abstract Combining magnetic-resonance imaging (MRI) and proton therapy (PT) using pencil-beam scanning (PBS) may improve image-guided radiotherapy. We aimed at assessing the impact of a magnetic field on PBS-PT plan quality and robustness. Specifically, the robustness against anatomical changes and positioning errors in an MRI-guided scenario with a 30 cm radius 1.5 T magnetic field was studied for prostate PT. Five prostate cancer patients with three consecutive CT images (CT1-3) were considered. Single-field uniform dose PBS-PT plans were generated on the segmented CT1 with Monte-Carlo-based treatment pla...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
CONCLUSIONS: Compared to using constant RBE, the variable RBE models predicted increased biological doses to the rectum, bladder and prostate, which in turn lead to substantially higher estimated rectum and bladder NTCPs. PMID: 29037095 [PubMed - as supplied by publisher]
Source: Acta Oncologica - Category: Cancer & Oncology Authors: Tags: Acta Oncol Source Type: research
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