RESUMEN
The study was conducted at the Radiation and Isotopes Center of Khartoum [RICK] during the period April 2009- August 2009. The aim of the study was to verify the superimposition of light and radiation field size on Cobalt-60 machine using image processing technique. The portal films used in the test were scanned using digitizer scanner. Then they analyzed using Interactive Digital Language [IDL] program to show the superimposition, in which more concentration was made on field center and borders, provided that the analysis included the four borders of the two fields. Both the standard deviation and the mean methods were used in the analysis process. For all score variations in this study t-test had been performed. P-value was calculated to show if there was any significant impact of each light and radiation field size variation. The result was as follows [10.0 X10.0cm], Medical physicist score was [10.3 +/- 0.11608 X 10.3 +/- 0.099861 cm] and the field size that calculates by computerized score using IDL program was [9.9 +/- 0.036049 X 9.9 +/- 0.01123 cm]. This indicates that the was within the acceptable limits for the automatic reading, as compared with the manual reading in which the penumbra was [8mm] which was very high and risky for the treatment process