INFLUENCE OF THE PHANTOM SHAPE (SLAB, CYLINDER OR ALDERSON) ON THE PERFORMANCE OF AN Hp(3) EYE DOSEMETER

In the past, the operational quantity H-p(3) was defined for calibration purposes in a slab phantom. Recently, an additional phantom in the form of a cylinder has been suggested for eye lens dosimetry, as a cylinder much better approximates the shape of a human head. Therefore, this work investigates which of the two phantoms, slab or cylinder, is more suitable for calibrations and type tests of eye dosemeters. For that purpose, a typical H-p(3) eye dosemeter was irradiated on a slab, a cylinder and on a human-like Alderson phantom. It turned out that the response on the three phantoms is nearly equal for angles of radiation incidence up to 45A degrees and deviates only at larger angles of incidence. Thus, calibrations (usually performed at 0A degrees radiation incidence) are practically equivalent on both the slab and the cylinder phantoms. However, type tests (up to 75A degrees or even 90A degrees radiation incidence) should be carried out on a cylinder phantom, as also for large angles of incidence the response on the cylinder and the Alderson phantoms is rather similar, whereas the response on the slab significantly deviates from the one on the Alderson phantom.