Abstract
Background and purpose
In this study, we investigated IMRT QA using Statistical Process Control for the purpose
of comparing the processes of patient-specific measurements and the corresponding
independent computer calculations.
Materials and methods
Point dose data from the treatment planning system (TPS), independent computer calculations,
and physical measurements for prostate and head and neck cases were studied. Control
charts were used to analyze the IMRT QA processes from several institutions in the
academic and community setting. Control charts are a method to describe the performance
of a process. The width of the control chart limits (or action limits) describes the
process’ ability to meet clinical specifications of ±5%. In all, 24 process comparisons
were made (12 measurement QA and 12 independent computer calculation QA).
Results
For head and neck IMRT QA, the average process ability for the measurement QA was ±6.9% compared to ±7.2% for the independent computer calculation
QA. For prostate IMRT QA, the average process ability was 4.4% for both measurement QA and independent computer calculation QA. It was
found that 11 of the 24 processes were in control. At none of the institutions were
the processes of measurements and independent computer calculations both in control
and performing within clinical specifications.
Conclusion
There is room to improve the processes of IMRT QA measurements and independent computer
calculations. In situations where the improvement of the processes is such that each
is in control and well within clinical specifications, it may be appropriate to suspend
patient-specific IMRT QA measurements for every patient in the place of independent
computer calculations.
Keywords
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Article info
Publication history
Published online: August 13, 2008
Accepted:
July 6,
2008
Received in revised form:
June 27,
2008
Received:
May 5,
2008
Identification
Copyright
© 2008 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
