Reduction of patient exposure in routine x-ray diagnosis

Exposure in X-ray diagnosis was critical in spite that exposure dose of each examination was little, because exposed population was large. In our study, exposure dose by routine diagnostic roentgenography could successfully reduce to 20 per cent of that under the standard condition. Reduction of exposure dose was achieved by using intensifying screen, such as MS, LT-II, and MSS for examination of infant pelvis, and obsterical abdomen, and film as Sakura QS or Fuji Rx-s. X-ray quality was hardened by adding filter of 2mm Al, and total filtration was made up to 4 mm Al equivalent. Tube voltage was elevated to obtain favorable picture within short exposure time. Victoreen r-meter and Kyokko TLD1200 Type, elemental device included in Mg2SiO4 glass capsule, and water phantom were used for dosimetry. Area exposure dose in fluoroscopy was measured in the digestive tract exam. using Hitachi dose monitor. Above mentioned exposure factors were combined, and under each conditions, exposure dose of the skin in various regions of the body. Chest roentgenography using LT-II screen showed 25 mR of exposure dose obtaining 63 per cent reduction from standard roentgenography without screen. Furthermore, use of QS film decreased the exposure dose to 17 mR (43 per cent), and added 0.5 mm Al filter reduced it to 13 mR (33 per cent). Finally, filter of 0.3 mm Cu and 0.5 mm Al reduced it to 8 mR (20 per cent of standard exposure dose). (Mukohata)