H. Tolli et Ka. Johansson, QUALITY ASSURANCE IN BRACHYTHERAPY - PRINCIPLES FOR IONIZATION-CHAMBER MEASUREMENT OF ABSORBED DOSE CLOSE TO BRACHYTHERAPY SOURCES, Physics in medicine and biology, 38(10), 1993, pp. 1475-1483
At present there exists no standardized procedure for absorbed dose de
termination with ionization chambers in the vicinity of brachytherapy
sources. In this paper, a modification of the IAEA formalism for exter
nal photon beams is proposed in order to make it applicable at a refer
ence point 20 mm from brachytherapy sources as well. A non-uniformity
correction factor is introduced to correct for the effects of the stee
p absorbed dose gradient, and it is concluded that reasonable accuracy
is possible when the Bragg-Gray principle is assumed to be valid.