Evaluating Electronic Portal Imaging Device for small field measurements
A Aziz Sait,
United States Minor Outlying Island
PO-1531
Abstract
Evaluating Electronic Portal Imaging Device for small field measurements
Authors: A Aziz Sait1,2, Tusar Patel2, Nikhil Rastogi1, SA Yoganathan3, Sunil Mani4, Jason Berilgen5, Raghavendiran Boopathy6
1IFTM University, Physics, Moradabad, India; 2Advanced Medical Physics Inc., Medical Physics, Houston, United States Minor Outlying Island; 3NCCCR, Hamad Medical Corporation, Radiation Oncology, Doha, Qatar; 4Advanced Medical Physics Inc. , Medical Physics, Houston, United States Minor Outlying Island; 5Millennium Physicians, Radiation Oncology, The Woodlands, United States Minor Outlying Island; 6School of Medicine, OHSU, Radiation Medicine, Portland, United States Minor Outlying Island
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Purpose or Objective
Small
field measurement is a challenging and time-consuming task. Although, many
high-resolution detectors are commercially available, the performance of Electronic
Portal Imaging Devices (EPID) is yet to be explored thoroughly for small field
dosimetry. Therefore, the objective of this study is to evaluate the EPID for small
field dosimetry commissioning and verification.
Material and Methods
Six
high-resolution radiation detectors (EPID, Pinpoint 3D ionization chamber, W2
plastic scintillators, microDiamond, microSilicone and Edge detector) were used
for the small field measurements. Output factors, profiles, depth doses were
measured for various beam energies (6MV,6MV FFF, 10MV and 10MVFFF) and field
sizes (10x10cm2, 5x5cm2, 4x4cm2, 3x3cm2, 2x2cm2, 1x1cm2, 0.5x0.5cm2) in a
Varian True Beam Linear accelerator. Acrylic plates of appropriate depth were
placed on the EPID during measurements, whereas Sun nuclear 3D water tank was
used with the five point detectors. EPID measured data were compared with the
reference golden beam data provided by Varian for field sizes up to 3x3cm2 and
remaining small field data were compared with published data, as well as with
other five high-resolution detector measurements.
Results
Results
showed that EPID output factors, profiles and depth dose deviations for fields
>3x3cm2 were up to ±3%, compared to golden beam data and other high
resolution detector data. For the remaining small fields (0.5x0.5cm2 - 3x3cm2),
the difference was observed to be 4%, compared to published data and other
small field detectors.
Conclusion
The
EPID can be used a small field dosimetry tool for the commissioning and verification
measurements with the effective correction factors.