Background:While modern nonionizing imaging systems such as magnetic resonance imaging offer undeniable advantages including lack of radiation and better image quality, the availability and lower cost of conventional X-ray examinations make them remain a cornerstone of diagnosis. While being highly helpful in the diagnosis of diseases, radiological examinations may involve potential risks. One of the most efficient dose reducing methods requiring no additional cost is the use of optimized projections instead of the traditionally accepted projections.
Objectives:The goals of the present study were the calculation and comparison of the effective doses and the risks of exposure induced cancer in male and female patients for different projections of the abdomen, the pelvis, and the lumbar spine X-ray examinations.
Patients and Methods:Radiographies of lumbar spine [in the eight projections of anteroposterior (AP), posteroanterior (PA), right lateral (RLAT), left lateral (LLAT), right anterior-posterior oblique (RAO), left anterior-posterior oblique (LAO), right posterior-anterior oblique (RPO), and left posterior-anterior oblique (LPO)], abdomen (in the two projections of AP and PA), and pelvis (in the two projections of AP and PA) were investigated. A solid-state dosimeter was used for the measurement of skin exposure. A Monte Carlo program was used for calculation of effective doses and the risks of radiation-induced cancer related to the different projections.
Results:Results of this study showed that PA projection of abdomen, lumbar spine, and pelvis radiographies caused 50%-57% lower effective doses than AP projection and a 50%-60% reduction in radiation risks. Also, the use of LAO projection in lumbar spine X-ray examination caused 53% lower effective dose than RPO projection and 56% and 63% reduction in radiation risk for male and female patients respectively. Furthermore, RAO projection caused a 28% lower effective dose than LPO projection and 52% and 39% reduction in radiation risk for male and female patients respectively.
Conclusions:Results of this study may introduce preferable projections for reduction of the effective dose and the risk of radiation-induced cancer. Recommended projection, whenever possible, for abdomen and pelvis X-ray examinations should be the PA projection rather than AP projection. Also, suggested projections for lumbar spine radiography should be PA rather than AP, LAO rather than RPO, RAO rather than LPO, and for men, RLAT rather than LLAT.
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