Denoising proton reference dosimetry spectrum using a large area ionization chamber - physical basis and type A uncertainty.

Reference dosimetry measurement in a pencil beam scanning system can exhibit dose fluctuation due to intra-spill spot positional drift. This results in a noisy reference dosimetry measurement against energy which could introduce errors in monitor unit calibration. The aim of this study is to investigate the impact of smoothing the reference dosimetry measurements on the type A uncertainty.

A treatment-site-specific evaluation of commercial synthetic computed tomography solutions for proton therapy.

Background And Purpose: Despite the superior dose conformity of proton therapy, the dose distribution is sensitive to daily anatomical changes, which can affect treatment accuracy. This study evaluated the dose recalculation accuracy of two synthetic computed tomography (sCT) generation algorithms in a commercial treatment planning system.

Materials And Methods: The evaluation was conducted for head-and-neck, thorax-and-abdomen, and pelvis sites treated with proton therapy.

Proton Beam Range and Charge Verification Using Multilayer Faraday Collector.

Purpose: A daily quality assurance (QA) check in proton therapy is ensuring that the range of each proton beam energy in water is accurate to 1 mm. This is important for ensuring that the tumor is adequately irradiated while minimizing damage to surrounding healthy tissue. It is also important to verify the total charge collected against the beam model.

Real-time gated proton therapy with a reduced source to imager distance: Commissioning and quality assurance.

Introduction: Real-time gated proton therapy (RGPT) is a motion management technique unique to the Hitachi particle therapy system. It uses pulsed fluoroscopy to track an implanted fiducial marker. There are currently no published guidelines on how to conduct the commissioning and quality assurance.

Repurposing DailyQA3 for an efficient and spot position sensitive daily quality assurance tool for proton therapy.

Introduction: Daily quality assurance is an integral part of a radiotherapy workflow to ensure the dose is delivered safely and accurately to the patient. It is performed before the first treatment of the day and needs to be time and cost efficient for a multiple gantries proton center. In this study, we introduced an efficient method to perform QA for output constancy, range verification, spot positioning accuracy and imaging and proton beam isocenter coincidence with DailyQA3.

First clinical experience following the consensus guide for calibrating a proton stopping power ratio curve in a new proton centre.

Background And Purpose: This work introduces the first assessment of CT calibration following the ESTRO's consensus guidelines and validating the HLUT through the irradiation of biological material.

Methods: Two electron density phantoms were scanned with two CT scanners using two CT scan energies. The stopping power ratio (SPR) and mass density (MD) HLUTs for different CT scan energies were derived using Schneider's and ESTRO's methods.

Effects of modern aesthetic dental fillings on proton therapy.

Background And Purpose: High-density dental fillings pose a non-negligible impact on head and neck cancer treatment. For proton therapy, stopping power ratio (SPR) prediction will be significantly impaired by the associated image artifacts. Dose perturbation is also inevitable, compromising the treatment plan quality.

Implementing dispersion measurement as part of scanning proton therapy commissioning and quality assurance.

. Dispersion in an accelerator quantifies the deviation of the proton trajectory when there is a momentum deviation. We present for the first time a safe method of measuring dispersion in the clinic, using a scintillator detector and the momentum deviations within a spill.

The effect of spill change on reliable absolute dosimetry in a synchrotron proton spot scanning system.

Background: Absolute dosimetry measurement is an integral part of Treatment Planning System (TPS) commissioning and it involves measuring the integrated absorbed dose to water for all energies in a pencil beam scanning delivery system. During the commissioning of Singapore's first proton therapy center, a uniform scanned field with an Advanced Markus chamber method was employed for this measurement, and a large dose fluctuation of at least 5% was observed for 10% of the energy layers during repeated measurements.

Purpose: This study aims to understand the root cause of this fluctuation by relating the actual delivered spot information in the log file with the charge measurement by the ion chambers.