Intang, Wilfred
(2021)
Evaluation of optimum measurement device, time analysis and workload of performing quality assurance tasks by physicists on medical linear accelerator.
Masters thesis, Universiti Sains Malaysia.
Abstract
The implementation of the Radiotherapy Quality Assurance Program (QAP)
safety standard by Malaysia Ministry of Health (KKM) is to ensure safe and
efficacious application of ionizing radiation and minimize error in the treatment of
cancer. With the new advance treatment technique and with the increasing number of
cancer patients, the QAP implementation is crucially important. But this also demands
a lot of physicist’s working time. Lack of physicist and quality control (qc) device
were among the problem encountered by most of the radiotherapy services in this
country as reported by NHEWS Report (2010) and this has become a major issue for
the QAP system to be in place. Therefore, it is particularly important to optimize
whatever resources available. This study has made some recommendations regarding
the qc tools suitably optimize for specific tasks. EPID is the best option for the quality
control (qc) device. It had recorded flatness standard deviation of 0.77 percent, while
the measured standard deviation of symmetry was 0.33 percent. EPID also provide
sufficiently accurate measurement for the light and radiation field congruent test. With
task timing, the Total Man Hours per linac for the machine qc was 62 Man-Hours per
year or 5.2 Man-Hours per month. For a typical radiotherapy clinic, this translates to
approximately five physicists per linac machine. The patient specific qc task had
recorded approximately 42 Man-Hours per year of physicist’s working time, higher
compared the other qc tasks. This is equivalent to 3.5 Man-Hours per month or
approximately four physicists that required to perform this task. Both calculation in
the WISN method and Man-Hours method had concluded that nine physicists are
required in Sabah Women and Children Hospital (HWKKS), while the actual number
of physicists working there at the time of this study was six. It means shortage of three
physicists or equivalent to 0.67 by ratio calculation of the WISN. At the time of this
research, there are limited or probably no evaluation study on qc device as well as the
timing qc task study with respect to the implementation of the QAP radiotherapy
standard in this country. By evaluate these QAP requirements, the gap between optimal
and actual use of resources was identified. Different approach of methods such as using
the Failure Modes and Effects Analysis (FMEA) in the qc program was recommended.
The research was conducted on four medical linac in two hospitals.
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