Pre-treatment verification of intensity modulated radiation therapy plans using a commercial electronic portal dosimetry system |
| |
Authors: | Kathleen J Roxby Jeffrey C Crosbie |
| |
Institution: | (1) William Buckland Radiotherapy Centre, The Alfred, Commercial Road, Melbourne, VIC, 3004, Australia;(2) Centre for Women’s Health Research, Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC, Australia;(3) Monash Centre for Synchrotron Science, Monash University, Clayton, VIC, Australia |
| |
Abstract: | We commissioned a commercially available portal dosimetry system for quality assurance of intensity modulated radiation therapy
(IMRT) treatment plans. The system included gamma analysis software to compare the measured and predicted fluence maps from
individual IMRT fields. The portal dosimetry system was tested using six head and neck IMRT patient plans, and we demonstrated
that the accuracy of the alignment of measured and predicted images improved by retracting and repositioning the electronic
portal imaging device (EPID) at each new gantry angle. The mean gamma score (fraction of pixels passing the gamma criteria)
for the six test plans (after initial testing and using the EPID retracting and repositioning method) was 0.987 (2SD = 0.018),
using gamma criteria of a dose difference of 2% of the maximum field dose and 2 mm distance to agreement. The mean gamma score
was 0.989 (2SD = 0.017) for 24 head and neck IMRT patient plans carried out with portal dosimetry. Using gamma criteria of
2% maximum field dose and 2 mm distance to agreement, a gamma score tolerance of 0.980 is a useful way of highlighting only
those fields requiring further analysis. Portal dosimetry is a quick way of assessing individual field fluence distributions
and can be integrated into an IMRT quality assurance programme. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|