Assessment of Field Size on Radiotherapy Machine using Image Texture Analysis

Abstract

The verification of light and radiation field is essential for radiotherapy process if the light field does not match the radiation field that resulting from central axis dose measurements and treatment planning account to about 5% of an optimal situation which the uncertainties so an effective quality assurance program should include port film reviews, and tests of machines for beam alignment. This study was performed in Radiation and Isotopes Center of Khartoum (RICK) in period of May 2013 to September 2013. The main objective of this study was to verify the superimposition of light and radiation field automatically by using image processing technique. For radiotherapy machines (Co-60 and linear acceralator) each film scanned using digitizer scanner then treat by using image processing program Mat Lab, where the congruence of the light and radiation field should be determined. The scanned image will be saved in a TIFF file format to preserve the quality of the image. The data analyzed include upper, lower, right and left borders of the light and radiation field in megavoltage films. The result showed that the mean and standard deviation light field size was (10.0 X 10.1cm), Medical physicist score was (10.2 ± 0.11608 X 10.2 ± 0.099861 cm) and the field size that calculate by computerized score using Mat Lab program was (9.9 ± 0.36049 X 9.9 ± 0.1123cm), the result also showed that the Computerized score is more accurate in determining of borders and Penumbra than medical physicist score. The computerized score technique, even in relatively simple images, could be disturbed by noise, creating some small regions that required additional processing. On the contrary, the manual method ignored those details to focus only on the expected boundaries which were determinate incorrect.