Based on radiation simulations for the transport of monoenergetic photons through right-angled circular cylinder phantoms, the conversion coefficients between receptor-free air collision kerma and the collision kerma for 4-element ICRU tissue have been investigated for extended plane-parallel X ray beams in two 1.9 cm rod phantoms and two 7.3 cm pillar phantoms 30 cm in length made of 4-element ICRU tissue or PMMA; the X ray beam direction was perpendicular to the phantoms' main axis. Two different types of quantities were calculated for each phantom, (i) the conversion coefficient at that point in the circular middle plane of the phantom perpendicular to its main axis which is localised at a depth of 0.007 g.cm-2 on the radius opposed to the beam direction and (ii) the angular dependence factor which describes the change of the conversion coefficient at the same point in the phantom after performing a rotation around the phantom's main axis. All these data, in particular those for the tissue phantoms, are of interest in the procedure for calibrating and type testing extremity dosemeters; the data on rod phantoms for finger dosemeters and those on pillar phantoms for wrist and ankle dosemeters.
