Using detector arrays to improve the efficiency of linear accelerator quality assurance and radiation data collection

The complexity of radiation therapy is continually increasing as new treatment modalities are implemented in the clinic. While these advances often benefit tumor dose localization, they also increase pressure on departmental resources as the new modality is adopted. This driving force comes at a time of increased pressure to perform quality assurance (QA) of the entire treatment process. The effect is a work force with too many measurements to do and not enough time in which to do them. The purpose of this work is to establish the use of detector arrays to improve the automation and efficiency of linear accelerator (LINAC) quality assurance and radiation data collection.;Two traditionally time consuming measurement processes were evaluated for the potential for increased efficiency and automation: multi-leaf collimator (MLC) calibration and scanning water tank measurements. Using traditional measurement techniques, MLC calibration can take hours to accomplish with mixed results or require a significant investment of time to write in-house software. We developed a quantitative and efficient (less than 30 minutes for both leaf banks) MLC calibration method that we termed the radiation defined reference line (RDRL) method. The method uses a detector array [PROFILER 2(TM); Sun Nuclear Corporation (SNC), Melbourne, FL USA] to measure the penumbral position of each leaf relative to a known reference point (or line).;Profile measurements are typically obtained with a scanning water tank. While time tested, the system requires above average skill and time to properly setup and acquire data. We extensively characterized and assessed the potential of a multi-axis ionization chamber array (IC PROFILER(TM); SNC) to measure water tank equivalent profiles. The IC PROFILER(TM) had an error spread of approximately (+/-) 0.75% relative to a water scan, with the potential of a positive offset in that error. During the characterization, the array calibration method was found to be susceptible to the LINACs symmetry stability. Symmetry variations of (+/-) 0.1% can cause calibration errors of (+/-) 2%. The cause was investigated and corrective measures were developed. Finally, a time efficient QA program was developed to determine the operation of the detector arrays.