To minimize radiation exposure,proper collimation and gonadal shielding should be employed,and film must be limited to the area of clinical concern. Roentgenograms should be taken in the radiology department whenever posible rather with portable equipment.The area of greatest interest should generally be placed closest to the film,and the patient should be properly positioned and gently immobilized if necessary. Exposure time should be short to minimize motion artifact,particulary in infants.