Logo image
Back
TU‐A‐108‐06: Computing Proton Dose to Irregularly Moving Targets
Conference proceeding   Peer reviewed

TU‐A‐108‐06: Computing Proton Dose to Irregularly Moving Targets

J Phillips, G Gueorguiev, J Shackleford, C Grassberger, S Dowdell, H Paganetti and G Sharp
Medical Physics, v 40(6), pp 420-420
Jun 2013
DOI: https://doi.org/10.1118/1.4815329

Abstract

Purpose: While 4DCT and deformable registration can be used to assess the dose delivered toregularly moving targets, there are currently few methods available for irregularly moving targets. This study describes a method for computing the dose delivered to irregularly moving targets basedon 1D or 3D waveforms captured at the time of delivery. Methods: The procedure requires 4DCT images for dose calculation, and 1D or 3D respiratorywaveforms to estimate target position at time of delivery. Dose volumes are converted from their Cartesian geometry into a beam‐specific radiological depth space, parameterized in 2D by the beamaperture, and longitudinally by the radiological depth. In this water‐equivalent depth space, the proton doses are translated according to the motion found in the 1D or 3D trajectory. These translated dose volumes are weighted and summed, then transformed back into Cartesian space,yielding an estimate of the dose that includes the effect of the measured breathing motion. Results: The method was validated using a synthetic lung CT phantom with a mobile tumor. Simulated 4DCT was generated for the phantom with 2 cm peak‐to‐peak motion. A passively‐scattered proton treatment plan was generated using a 7 mm smearing radius. The method wastested without motion, and with two simulated breathing signals: a 2 cm amplitude sinusoid, anda 2 cm amplitude sinusoid with 3 cm linear drift. Motion‐corrected dose was computed based onthe mid‐ventilation CT image. Gamma evaluation (3 mm, 3%) was 98.7% without motion, 92.9%for 2 cm sinusoidal motion, and 98.0% with 3 cm drift. Conclusion: We have demonstrated a method for accurately reproducing proton dose to anirregularly moving target from a single CT image. We believe this algorithm could prove a usefultool to study the dosimetric impact of baseline shifts either before or during treatment.

Metrics

14 Record Views

Details

InCites Highlights

Data related to this publication, from InCites Benchmarking & Analytics tool:

Web of Science research areas
Radiology, Nuclear Medicine & Medical Imaging
Logo image