Imaging plate as a dosimeter for estimating ambient dose equivalent of scattered radiations and skin dose of patients in interventional radiology procedures

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Imaging plates (IPs) were applied to a passive dosimeter for measuring high level X-ray radiation and, then, estimating skin dose of patients and ambient dose equivalent of scattered radiations in interventional radiology (IR) procedures. Results were obtained as follows.1.Two new techniques of using color cellophane and annealing to measure high dose X-ray radiation have been developed. These techniques can extend the dynamic range and upper limit of a linearity of BAS-TR up to 10^2 Gy and 10 Gy, respectively.2.BAS-TR's characteristics were investigated by irradiating X-ray for tube voltages of 60 to 120 kV, which are used in IR procedures. Sensitivity variations of from 13 to 33% was observed, though it changed according to types of X-ray unit. To estimate doses of X-ray radiation accurately, an average tuve voltage should be obtained during IR procedures. The significant difference according to angular changes of incidences was not observed up to ±75° at any tube voltages except -90° or +90°.3.An entrance skin dose (ESD) was measured in clinical studies by fitting a large sheet of IPs around a patient's back using a corset, which lessens a geometric discrepancy in dose estimate between IP and the patient body. The ESD obtained by IPs was compared with that obtained by a photoluminescence glass dosemeter (PLD) chip. Both doses show agreement, overall in all dose range, however, the doses obtained with the PLD chips were consistently lower than those obtained with the IPs. It comes from a sensitivity variation caused by an angular dependence of the PLD chip.4.A flat energy response to the dose equivalent was obtained by the sensitivity data measured under different metal filters attached BAS-MS. The ambient dose equivalent can be evaluated by using a flat response, without requiring knowledge of the effective energies of scattered photon radiations.