Detection of anatomical changes in lung cancer patients with 2D time-integrated, 2D time-resolved and 3D time-integrated portal dosimetry: a simulation study.

Detection of anatomical changes in lung cancer patients with 2D time-integrated, 2D time-resolved and 3D time-integrated portal dosimetry: a simulation study.
Phys Med Biol. 2017 Jun 05;:
Authors: Wolfs CJA, Brás M, Schyns L, Nijsten S, van Elmpt W, Scheib S, Baltes C, Podesta M, Verhaegen F
Abstract
The aim of this work is to assess the performance of 2D time-integrated (2D-TI), 2D time-resolved (2D-TR) and 3D time-integrated (3D-TI) portal dosimetry in detecting dose discrepancies between the planned and (simulated) delivered dose caused by simulated changes in the anatomy of lung cancer patients. 
 For six lung cancer patients, tumor shift, tumor regression and pleural effusion are simulated by modifying their CT images. Based on the modified CT images, time-integrated (TI) and time-resolved (TR) portal dose images (PDIs) are simulated and 3D-TI doses are calculated. The modified and original PDIs and 3D doses are compared by a gamma analysis with various gamma criteria. Furthermore, the difference in the D95% (ΔD95%) of the GTV is calculated and used as a gold standard. The correlation between the gamma fail rate and the ΔD95% is investigated, as well as the sensitivity and specificity of all combinations of portal dosimetry method, gamma criteria and gamma fail rate threshold.
 On the individual patient level, there is a correlation between the gamma fail rate and the ΔD95%, which cannot be found at the group...

Source: Physics in Medicine and Biology - June 5, 2017 Category: Physics Authors: Wolfs CJA, Brás M, Schyns L, Nijsten S, van Elmpt W, Scheib S, Baltes C, Podesta M, Verhaegen F Tags: Phys Med Biol Source Type: research