TY - JOUR
T1 - Commissioning and periodic quality assurance of a clinical electronic portal imaging device
AU - Low, Daniel A.
AU - Klein, Eric E.
AU - Maag, Derek K.
AU - Umfleet, William E.
AU - Purdy, James A.
PY - 1996/1/1
Y1 - 1996/1/1
N2 - Purpose: An electronic portal imaging device (EPID) was recently installed on our dual-energy linear accelerator. Commissioning and quality assurance techniques were developed for the EPID. Methods and Materials: A commissioning procedure was developed consisting of five parts: (a) physical operation and safety; (b) image acquisition, resolution, and sensitivity calibration; (c) image storage, analysis, and handling; (d) reference image acquisition; and (e) clinical operations. Results: The physical operation and safety tests relate to the motions of the unit, stability of the unit supports, safety interlocks, and interlock overrides. Imager contrast and spatial resolutions are monitored by imaging a contrast-detail phantom. The imager calibration procedure consists of a no-radiation image to compensate for signal offsets, as well as a 'flat-field image.' The flat-field image is taken with 5.0 cm of homogeneous phantom material placed at isocenter to provide some photon scatter and to approximate the presence of a patient. Daily quality assurance procedures consists of safety tests and the acquisition and inspection of images of the contrast-detail phantom. After 1 year, the frequency of the daily procedure was reduced to weekly. Quarterly QA procedures are conducted by the physicist and consist of the same procedures conducted in the weekly test. The annual QA procedure consists of a duplication of the commissioning procedure. Conclusion: The procedures discussed in this article were applied to an ionization-chamber device. They have been useful in identifying difficulties with the EPID operation, including the need for recalibrating and monitoring the accelerator output stability.
AB - Purpose: An electronic portal imaging device (EPID) was recently installed on our dual-energy linear accelerator. Commissioning and quality assurance techniques were developed for the EPID. Methods and Materials: A commissioning procedure was developed consisting of five parts: (a) physical operation and safety; (b) image acquisition, resolution, and sensitivity calibration; (c) image storage, analysis, and handling; (d) reference image acquisition; and (e) clinical operations. Results: The physical operation and safety tests relate to the motions of the unit, stability of the unit supports, safety interlocks, and interlock overrides. Imager contrast and spatial resolutions are monitored by imaging a contrast-detail phantom. The imager calibration procedure consists of a no-radiation image to compensate for signal offsets, as well as a 'flat-field image.' The flat-field image is taken with 5.0 cm of homogeneous phantom material placed at isocenter to provide some photon scatter and to approximate the presence of a patient. Daily quality assurance procedures consists of safety tests and the acquisition and inspection of images of the contrast-detail phantom. After 1 year, the frequency of the daily procedure was reduced to weekly. Quarterly QA procedures are conducted by the physicist and consist of the same procedures conducted in the weekly test. The annual QA procedure consists of a duplication of the commissioning procedure. Conclusion: The procedures discussed in this article were applied to an ionization-chamber device. They have been useful in identifying difficulties with the EPID operation, including the need for recalibrating and monitoring the accelerator output stability.
KW - Electronic portal imaging devices
KW - On-line radiation therapy imaging
KW - Radiation therapy quality assurance
UR - http://www.scopus.com/inward/record.url?scp=0030051211&partnerID=8YFLogxK
U2 - 10.1016/0360-3016(95)02096-9
DO - 10.1016/0360-3016(95)02096-9
M3 - Article
C2 - 12118539
AN - SCOPUS:0030051211
SN - 0360-3016
VL - 34
SP - 117
EP - 123
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 1
ER -