Commissioning dose computation models for spot scanning proton beams in water for a commercially available treatment planning system.

Purpose: To present our method and experience in commissioning dose models in water for spot scanning proton therapy in a commercial treatment planning system (TPS).

Methods: The input data required by the TPS included in-air transverse profiles and integral depth doses (IDDs). All input data were obtained from Monte Carlo (MC) simulations that had been validated by measurements.

A procedure to determine the planar integral spot dose values of proton pencil beam spots.

Purpose: Planar integral spot dose (PISD) of proton pencil beam spots (PPBSs) is a required input parameter for beam modeling in some treatment planning systems used in proton therapy clinics. The measurement of PISD by using commercially available large area ionization chambers, like the PTW Bragg peak chamber (BPC), can have large uncertainties due to the size limitation of these chambers. This paper reports the results of our study of a novel method to determine PISD values from the measured lateral dose profiles and peak dose of the PPBS.

Patient-specific quality assurance for prostate cancer patients receiving spot scanning proton therapy using single-field uniform dose.

Purpose: To describe our experiences with patient-specific quality assurance (QA) for patients with prostate cancer receiving spot scanning proton therapy (SSPT) using single-field uniform dose (SFUD).

Methods And Materials: The first group of 249 patients with prostate cancer treated with SSPT using SFUD was included in this work. The scanning-beam planning target volume and number of monitor units were recorded and checked for consistency.

Verification of patient-specific dose distributions in proton therapy using a commercial two-dimensional ion chamber array.

Purpose: The purpose of this study was to determine whether a two-dimensional (2D) ion chamber array detector quickly and accurately measures patient-specific dose distributions in treatment with passively scattered and spot scanning proton beams.

Methods: The 2D ion chamber array detector MatriXX was used to measure the dose distributions in plastic water phantom from passively scattered and spot scanning proton beam fields planned for patient treatment. Planar dose distributions were measured using MatriXX, and the distributions were compared to those calculated using a treatment-planning system.

An MCNPX Monte Carlo model of a discrete spot scanning proton beam therapy nozzle.

Purpose: The purposes of this study were to validate a discrete spot scanning proton beam nozzle using the Monte Carlo (MC) code MCNPX and use the MC validated model to investigate the effects of a low-dose envelope, which surrounds the beam's central axis, on measurements of integral depth dose (IDD) profiles.

Methods: An accurate model of the discrete spot scanning beam nozzle from The University of Texas M. D.