Keywords:
Radiation physics, Radioprotection / Radiation dose, CT, Dosimetry, Physics, Radiation safety, Dosimetric comparison
Authors:
I. Kralik, B. Brkljacic, D. Cvetko, I. Hulina, M. Justić, J. Popić, I. Bjelobrk, T. Turk, D. Faj
Methods or background
Although recent recommendations suggest use of clinical DRLs instead of DRLs based on anatomical region [1,2], the previous practice in Croatia involved comparison of typical doses with the national DRLs (hereinafter: nDRL) which are based on the anatomical regions since Croatian legislation still does not recognize clinical DRLs [3].
In order to investigate to which level practice in Croatia is in line with the recent recommendations, comparison of typical values of CT dosimetric quantities for clinical indications was performed. Three university hospitals with six CT units of five different manufacturers were involved in this study. Typical values for 10 clinical indications for which EU clinical DRLs are given in RP 195 were calculated for CTDIvol, DLP and scanning length (L) for each phase as well as for total DLP. Typical values were then compared with EU DRL values given in RP 195 for CTDIvol per phase (CTDIvol,p), DLP per phase (DLPp), total DLP (DLPt) and scan length. Calculated typical values for CTDIvol were compared with national DRL values too (nDRL is not given for scan length). Since current list of nDRLs does not specify whether given nDRL value for DLP is for DLP per phase or for total DLP, calculated typical values for DLP for each phase and for total DLP were both compared with nDRL value given for DLP. Topogram (scout), pre-monitoring and monitoring phases were not included in calculation. The aim was to collect data for at least 30 standard patients if DMS was unavailable and for more than 100 patients in case of hospitals where DMS is available as recommended [4], for each CT unit and clinical indication.