Reduction of radiation dose by using digital luminescence radiography on ahand phantom.

Purpose: How much can the radiation dose be reduced for hand radiography by using digital luminescence radiography (DLR)? Methods and Materials: A han d phantom (3M) with a cyst, two fractures and an "amputation" was digitally exposed in an anterior-posterior orientation using DLR (ADC-70, Agfa). The tube current time product (mAs) was reduced gradually while keeping the vo ltage constant. The surface entrance dose was measured by a Dosimax sensor (Wellhofer). Five investigators evaluated the images for characteristics an d critical features, pathological findings, visual resolution and contrast. Results: The surface entrance dose at 50 kV/5 mAs was 31 mu Gy. The images could be evaluated very well down to an average dose of 36% (11 mu Gy); su fficient images were obtained down to an average dose of 26% (8 mu Gy). The resolution of the line pairs was the same or reduced by 1 level depending on the investigator. Contrast was assessed as being very good to sufficient . Conclusion: For the sufficient exclusion of a fracture the dose can be re duced to at least 39%, for the sufficient assessment of bony union and poss ible inflammatory changes to at least 42%, to position check and foreign bo dy search to at least 23%. By DLR the following question-referred mAs-produ ct at 50 kV are stated: fracture exclusion 2 mAs, bony union, arthritis and osteomyelitis 2.2 mAs, position check and foreign body search 1.25 mAs.