A Method of Testing a Focussed Collimator for Radioisotope Scanning

Abstract

X-ray films sandwiched between metacrylate plates were exposed through holes of a collimator vertically or horizontally to the gamma ray beam of ¹³¹I kept in the place of NaI (T1) crystal instead.
The results showed the leakage of gamma rays through 6 corners of weak shielding of a 5 cm focus collimator, which was built for the scanning of ¹³¹I in tissues.
However the leakage disappeared when the shielding was reinforced by inserting lead casts to the central holes.
A 10 cm focus collimator showed a longer and narrower focus than the 5 cm focus collimators.
This test does not need scanner, therefore the results are simple, reproducible, and useful for the comparison, and planning of collimators.