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Journal of Applied Science & Engineering

Dhaka University Journal of Applied Science & Engineering

Issue: Vol. 5, No. 1 & 2, January & July 2020
Title: Experimental Study on Cross-calibrating Ideology for Small Field Dosimetry by High Spatial Resolution Detector

Keywords: Absorbed Dose, Cross-calibration Factor, Multi-Leaf Collimator (MLC), Institutional Output Factor

The study regulates the absorbed dose to water as well as output factors for small fields using IAEA TRS-398 protocol and corrects the results by determining a cross-calibration factor for small fields using German dosimeter standard DIN 6809-8. Herein, we collected several datasets of small-field output factor for two separate values of X-ray energy, 6 MV and 10 MV, from a Varian CLINAC 2100 linear accelerator. The measurements for the datasets had been taken at a depth of 10 cm and varied between 10 × 10 cm² to 2 × 2 cm². Using the Multi-Leaf Collimator (MLC), the fields were outlined and the jaws (secondary) were preserved at 10 × 10 cm². With a PTW TM60012 silicon diode detector, the measurements were made. The volume of this detector is sufficiently small to collect a complete ionization reading for a small-field having a size of 2 × 2 cm². The calibration factors obtained from 4 × 4 cm² were 1.038 (for 6MV X-Ray) and 1.042 (for 10MV X-Ray). This calibration factors can successfully reproduce the institutional output factors from diode detector readings with a variation of maximum 0.6% to minimum 0.1%.

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