当前位置： SCI文献检索 > Journal of Applied Clinical Medical Physics期刊下所有文献 > Investigation of error detection capabilities of phantom, EPID and MLC log file based IMRT QA methods.

Investigation of error detection capabilities of phantom, EPID and MLC log file based IMRT QA methods.

Abstract：

:A patient specific quality assurance (QA) should detect errors that originate anywhere in the treatment planning process. However, the increasing complexity of treatment plans has increased the need for improvements in the accuracy of the patient specific pretreatment verification process. This has led to the utilization of higher resolution QA methods such as the electronic portal imaging device (EPID) as well as MLC log files and it is important to know the types of errors that can be detected with these methods. In this study, we will compare the ability of three QA methods (Delta4 ®, MU-EPID, Dynalog QA) to detect specific errors. Multileaf collimator (MLC) errors, gantry angle, and dose errors were introduced into five volumetric modulated arc therapy (VMAT) plans for a total of 30 plans containing errors. The original plans (without errors) were measured five times with each method to set a threshold for detectability using two standard deviations from the mean and receiver operating characteristic (ROC) derived limits. Gamma passing percentages as well as percentage error of planning target volume (PTV) were used for passing determination. When applying the standard 95% pass rate at 3%/3 mm gamma analysis errors were detected at a rate of 47, 70, and 27% for the Delta4 , MU-EPID and Dynalog QA respectively. When using thresholds set at 2 standard deviations from our base line measurements errors were detected at a rate of 60, 30, and 47% for the Delta4 , MU-EPID and Dynalog QA respectively. When using ROC derived thresholds errors were detected at a rate of 60, 27, and 47% for the Delta4 , MU-EPID and Dynalog QA respectively. When using dose to the PTV and the Dynalog method 11 of the 15 small MLC errors were detected while none were caught using gamma analysis. A combination of the EPID and Dynalog QA methods (scaling Dynalog doses using EPID images) matches the detection capabilities of the Delta4 by adding additional comparison metrics. These additional metrics are vital in relating the QA measurement to the dose received by the patient which is ultimately what is being confirmed.

journal_name

J Appl Clin Med Phys

journal_title

Journal of applied clinical medical physics

authors

Defoor DL,Stathakis S,Roring JE,Kirby NA,Mavroidis P,Obeidat M,Papanikolaou N

doi

10.1002/acm2.12114

subject

Has Abstract

pub_date

2017-07-01 00:00:00

pages

172-179

issue

issn

1526-9914

journal_volume

pub_type

杂志文章

在线工具

Investigation of error detection capabilities of phantom, EPID and MLC log file based IMRT QA methods.