It is well established that diagnostic X-ray practices must be optimised to keep patient radiation dose as low as compatible with providing the diagnostic information required. For effective optimisation of diagnostic exposures, the International Commission on Radiological Protection (ICRP) introduced the concept of diagnostic reference levels (DRLs) in 1996. The present study aimed to carry out an extensive dose survey of diagnostic radiography installations in the Uttarakhand region of India to establish local DRL Values for the different diagnostic practices. During the survey, air kerma values were measured for 297 diagnostic X-ray machines installed at 270 medical centres in the region and the entrance surface air kerma (K a,e) was estimated for ten commonly performed radiographic projections. These included chest posterior-anterior (PA), cervical spine anterior-posterior (AP), skull PA, abdomen AP, KUB (kidney, ureter and bladder), lumbar spine AP, lumbar spine lateral (LAT), pelvis AP, thoracic spine AP, and thoracic spine LAT. Wide variations were observed in the estimated values of K a,e for individual projections. The third quartile of the distribution of the median values of the estimated K a,e for a given projection was calculated to establish local DRL Values. The majority of the acquired dose data were found to be comparable to or less than the proposed national and international DRLs. The local DRL Values reported in this study may be used to improve radiological practice by reducing patient doses during radiography examinations. The obtained data may also contribute to a national patient dose database for establishing future national DRLs.
Keywords: Diagnostic reference level (DRL); Dose survey; Entrance surface air kerma (K a,e); Radiographic projection.