Management of patient doses and diagnostic reference levels in X-ray radiography in Lithuania

Management of patient doses and determination of national or local diagnostic reference levels (DRLs) are important parts of a quality control program in X-ray diagnostics. In Lithuania, national DRLs for specific radiographic examinations are comparatively higher than those recommended by the European Commission (EC) and the International Atomic Energy Agency (IAEA). A survey of entrance surface doses (ESDs) was performed to investigate the reasons for exceeding the European and the IAEA DRLs. The first measurements showed that the average ESD for standard patients and for all examinations exceeded DRLs at approximately 25 % of the hospitals. The main problems were the use of low kilovolt technique, the lack of automatic exposure control systems or improper adjustment of them as well as inadequate training of the staff. After corrective actions, the ESD measurements were repeated. The results showed that the average patient doses were reduced almost everywhere. An additional patient dose survey for establishing new DRLs in radiography taking into account the advantages of new equipment to indicate directly the kerma area product (KAP) values was done. The ESD values were calculated from the KAP-values. The data were analysed, and the average and third quartile values were calculated. The new DRLs, in terms of ESDs, were reduced significantly in almost all radiography examinations. They are equal or lower than the IAEA and EC DRLs. Especially at thorax spine LAT, lumbar spine LAT, hip joint AP, pelvis AP and abdomen AP they are half the IAEA DRLs.