Residual range distribution measured by heavy ion radiography
The relationships of optical density of a heavy ion radiograph with residual range and with absorbed dose are discussed, and the experimentally obtained results of the residual range for the small animal tissue phantom are shown. It is found that the curve of optical density against PMMA equivalent thickness does not show a peak as seen in the depth dose distribution curve measured with an ionization chamber. This reflects the difference between the film and ionization chamber in their responses to high LET particles. The shapes of the curves of the optical density against the thickness of the range shifter are almost identical, but the amount of shift along the thickness differs depending on the density of the phantom tissues and corresponds to the difference of the residual range. Therefore the optical density curves against absorber thickness are suitable for estimating residual range of the heavy ions emitted from the downstream side of the phantom, pixel by pixel.
放射線医学物理 19(2), 108-113, 1999-06-30
Japan Society of Medical Physics