Reduction of radiation exposure by using storage phosphor radiography on pelvis and lumbar spine

Purpose: To examine the reduction of radiation dose for radiography of the pelvis and lumbar spine (LS) by using storage phosphor radiography (SPR)? Material and Methods: Each pelvis and LS of 2 phantoms (3 M) and 2 corpses were X-raxed digitally in an anterior-posterior orientation using SPR (ADC compact, Agfa). The tube current time product (mAs) was diminished gradually while keeping the voltage constant. The surface entrance dose was measured by a Dosimax (Wellhofer) sensor. Five investigators evaluated the images for characteristics and critical features and pathological findings. Results: The images of the 4 various pelvises/LS could be evaluated sufficiently down to an average dose of 34 to 40 %/18 to 35 %. For the assessment of hip joint, region typical corticalis and calcifications (pelvis/LS) 9 to 18 %/8 to 23 % of the initial dose (initial dose is equivalent to a conventional screen film system with a speed class of 400) are enough, spongiosa typical for the region and the sacrum 30 to 56 %/19 to 36 % on average among the readers. Conclusion: For the sufficient exclusion of a fracture the dose can be reduced on pelvis/LS to at least 39 %/28 % (diameter 23 %/17 %), for the assessment of sacroiliitis/ osteolyses/demineralisation to at least 78 %/44 % (diameter 34 to 36 %/ 22 to 26 %), to position check after fracture to at least 15 %/25 % (diameter 9 %/10 %). Question-related tube current time products of the pelvis and LS can be deduced for various objects.