Assessment of Radiation Therapy Treatment Field on Portal Film by Using Image Processing

Abstract

Several factors contribute to the accuracy of the delivered dose to patients in external-beam radiotherapy (EBRT). Although some of these factors can be checked by implementing suitable quality control procedures, films are highly recommended method for assessment of radiotherapy treatment field. This study was conducted at radiotherapy department, Radiation and Isotopes Center of Khartoum (RICK), Khartoum state, Sudan, from July 2014 up to December 2014. In order to assess the radiotherapy beam using portal film and by measuring the field size and the penumbra size and the uniformity. The field size of two type of co-60 was measured to be (9.4×9.4) cm and (9.1×9.1) cm, for linear accelerator machines it was 10×10 cm exactly as the reference field size, and there is no area reduced in liniacs. The penumbra size for the two type of co 60 machine was measured also and it was 1.2 cm and 1.0 cm, and the penumbra size of the linear accelerator machines was found to be 0.4cm and 0.4cm. The area of the field that received radiation by 100% was measured and it was 94.1 % and 91.1 % in co60 and 100 % for linear accelerator machine and that means liniacs deliver the 100% of the dose to the useful field size. The dose percentage in the field for co-60 was 98.0 % and 94.1 % and thus the dose in the border of field 83.1 % and 89.0 % and it’s different in liniacs because the dose percentage in the field was 78.4% and 78.4% and there is no measurable dose outside the field size of liniacs.