Prostate Stereotactic Body Radiation Therapy With Halcyon 2.0: Treatment Plans Comparison Based on RTOG 0938 Protocol.

Purpose The aim of this study is to investigate the feasibility of prostate stereotactic body radiation therapy treatment with a newly developed Varian Halcyon 2.0 machine by comparing radiotherapy plans with previously delivered CyberKnife G4 plans created with the previous version of CyberKnife Treatment Planning System Multiplan 4.6.

4D cone beam CT-based dose assessment for SBRT lung cancer treatment.

The purpose of this research is to develop a 4DCBCT-based dose assessment method for calculating actual delivered dose for patients with significant respiratory motion or anatomical changes during the course of SBRT. To address the limitation of 4DCT-based dose assessment, we propose to calculate the delivered dose using time-varying ('fluoroscopic') 3D patient images generated from a 4DCBCT-based motion model. The method includes four steps: (1) before each treatment, 4DCBCT data is acquired with the patient in treatment position, based on which a patient-specific motion model is created using a principal components analysis algorithm.

Targeted radiotherapy enhancement during electronic brachytherapy of accelerated partial breast irradiation (APBI) using controlled release of gold nanoparticles.

Several studies have demonstrated low rates of local recurrence with brachytherapy-based accelerated partial breast irradiation (APBI). However, long-term outcomes on toxicity (e.g.

Low-Z linac targets for low-MV gold nanoparticle radiation therapy.

Purpose: To investigate the potential of low-Z/low-MV (low-Z) linac targets for gold nanoparticle radiotherapy (GNPT) and to determine the microscopic dose enhancement ratio (DER) due to GNP for the alternative beamlines. In addition, to evaluate the degradation of dose enhancement arising from the increased attenuation of x rays and larger skin dose in water for the low-MV beams compared to the standard linac.

Methods: Monte Carlo simulations were used to compute dose and DER for various flattening-filter-free beams (2.

Dependence of Monte Carlo microdosimetric computations on the simulation geometry of gold nanoparticles.

Recently, interactions of x-rays with gold nanoparticles (GNPs) and the resulting dose enhancement have been studied using several Monte Carlo (MC) codes (Jones et al 2010 Med. Phys. 37 3809-16, Lechtman et al 2011 Phys.

Beam quality and dose perturbation of 6 MV flattening-filter-free linac.

The aim of this study is twofold: (a) determination of the spectral differences for flattening-filter-free (FFF) versus standard (STD) linac under various clinical conditions, (b) based on an extensive list of clinically important beam configurations, identification of clinical scenarios that lead to higher macroscopic dose perturbations due to the presence of high-Z material. The focus is on dose enhancement due to contrast agents including high-Z elements such as gold or gadolinium. EGSnrc was used to simulate clinical beams under various irradiation conditions: open/IMRT/spit-IMRT fields, in/out-off-field areas, different depths and field sizes.

A stochastic model of cell survival for high-Z nanoparticle radiotherapy.

Purpose: The authors present a stochastic framework for the assessment of cell survival in gold nanoparticle radiotherapy.

Methods: The authors derive the equations for the effective macroscopic dose enhancement for a population of cells with nonideal distribution of gold nanoparticles (GNP), allowing different number of GNP per cell and different distances with respect to the cellular target. They use the mixed Poisson distribution formalism to model the impact of the aforementioned physical factors on the effective dose enhancement.

Impact of beam quality on megavoltage radiotherapy treatment techniques utilizing gold nanoparticles for dose enhancement.

This study determines the optimal clinical scenarios for gold nanoparticle dose enhancement as a function of irradiation conditions and potential biological targets using megavoltage x-ray beams. Four hundred and eighty clinical beams were studied for different potential cellular or sub-cellular targets. Beam quality was determined based on a 6 MV linac with and without a flattening filter for various delivery conditions.