Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/222860

Title

Finding the optimal statistical model to describe target motion during radiotherapy delivery: a Bayesian approach

Author(s)

Herschtal, A.;  Foroudi, F.;  Greer, P. B.;  Eade, T. N.;  Hindson, B. R.;  Kron, T.

Abstract

Early approaches to characterizing errors in target displacement during a fractionated course of radiotherapy assumed that the underlying fraction-to-fraction variability in target displacement, known as the treatment error or random error, could be regarded as constant across patients. More recent approaches have modelled target displacement allowing for differences in random error between patients. However, until recently it has not been feasible to compare the goodness of fit of alternate models of random error rigorously. This is because the large volumes of real patient data necessary to distinguish between alternative models have only very recently become available. This work uses real-world displacement data collected from 365 patients undergoing radical radiotherapy for prostate cancer to compare five candidate models for target displacement. The simplest model assumes constant random errors across patients, while other models allow for random errors that vary according to one of several candidate distributions. Bayesian statistics and Markov Chain Monte Carlo simulation of the model parameters are used to compare model goodness of fit. We conclude that modelling the random error as inverse gamma distributed provides a clearly superior fit over all alternatives considered. This finding can facilitate more accurate margin recipes and correction strategies.

Publication type

Journal article

Research centre

Swinburne University of Technology

Source

Physics in Medicine and Biology, Vol. 57, no. 9 (May 2012), pp. 2743-2755

Publication year

2012

FOR Code(s)

0299 Other Physical Sciences;  0903 Biomedical Engineering

Keyword(s)

Bayesian modelling;  Prostate cancer;  Radiotherapy;  Random errors;  Target displacement

Publisher

Institute of Physics Publishing

ISSN

0031-9155

Publisher URL

http://dx.doi.org/10.1088/0031-9155/57/9/2743

Copyright

Copyright © 2012 Institute of Physics and Engineering in Medicine.

Research Projects

Optimising radiation therapy delivery for cancer patients using daily image guidance to maximize cure and reduce normal tissue side effects, National Health and Medical Research Council grant number 1023031

Peer reviewed