APPLICATION OF PTTL METHOD FOR DOSE REASSESSMENT IN EXTREMITY DOSIMETRY

Wide and common applications of ionising radiation require continuous improvement of radiation safety and dosimetry methods. The thermoluminescent (TL) method is well known and very popular. Apart from its advantages, it also carries certain disadvantages. The erasure of the TL signal on detector readout and the resulting impossibility of post-readout dose reassessment is one of them. At the Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN), a method for dose reassessment based on phototransferred thermoluminescence (PTTL) has been developed. This method has been applied for dose reassessment to MTS-N (LiF:Mg, Ti) detectors used in individual whole-body dosemeters and adjusted to an automatic reader used in routine measurements. The next step was to extend and adapt this method for extremity dosemeters. With the use of the PTTL method, it is possible to reassess relatively high doses measured on individual whole-body and extremity dosemeters collected from our customers after routine use. The influence of PTTL background has greater impact in extremity dosemeters where it is only one and thinner MTS-N detector compared with four MTS-N detectors in whole-body dosemeters. The minimum dose was determined as 5 mSv for extremity dosimetry. Below 5 mSv, the impact of PTTL background is comparable to the signal, and the estimated uncertainty of reassessed dose is at the level of reassessed dose.