Program Information
Charaterisation of a Two Dimensional Liquid Filled Ion Chamber Detector Array System in Flattened and Unflattened Photon Beams
Ganapathy Krishnan1*, Murali V2 , Muthukumaran M3 , S Chitra4 , S Grace5 , Vendhan S6 , (1) ,,,(2) Apollo Cancer Institutes, Chennai, Tamil Nadu, (3) ,,,(4) Apollo Cancer Institutes, Chennai, Tamil Nadu, (5) Anna University, Chennai, Tamilnadu, (6) Apollo Cancer Institutes, Chennai, Tamil Nadu
Presentations
SU-I-GPD-T-469 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: The objective of this study is to characterize a two dimensional liquid filled detector array SRS 1000 in flattened and unflattened photon beams used in radiotherapy
Methods: SRS 1000 detector array system consists 977 liquid filled ionization chambers (placed in a 11×11 cm² square region) designed to be used in QA of radiotherapy involving small fields. In the central 5.5×5.5 cm² region, chambers are placed at a special resolution of 2.5 mm. In the remaining area of the detector array, chambers are placed at a spacial resolution of 5mm. The dimensions of each of the 977 detectors is 2.3 × 2.3 0.5 mm with a volume of .003 cc. The characteristics of the detector array system is studied in flattened and unflattened beams of 6 MV and 10 MV X-rays delivered from a Varian TrueBeam STx linear accelerator. The parameters studied were MU Linearity, Reproducibility, Dose rate dependency and output factor. All the measurements from SRS 1000 detector array system were compared with the measurements using a PTW Pinpoint chamber
Results: To check the Linearity in response of the SRS 1000 detector array system measurements were made in the MU range of 10 to 1000. The MU linearity measurement by SRS 1000 detector array system was within a 2.3% agreement with the pinpoint chamber measurements. Dose rate dependency of the system was found to be within 1.45% agreement for the range of 10 MU/min to 2400 MU/min. The reproducibility of the measurements was studied at different time intervals and found to be within 0.3% deviation. Output factor measurements by SRS 1000 array system was found to be agreeing with the pinpoint chamber measurements with a maximum deviation of 2.3%.
Conclusion: PTW 1000 SRS array detector can be used in the routine QA checks of small field radiotherapy.
Contact Email: