Dose distribution at radiographic examination of the spine in pediatric radiology.

STUDY DESIGN: The radiation dose distribution at radiographic examinations of the lumbar spine and the thoracic spine and at examinations for scoliosis has been investigated in pediatric patients. OBJECTIVES: To derive the conversion factors between the entrance surface dose and the mean absorbed dose to the most radiation-sensitive organs, and to determine the dose level and its variation for patients. SUMMARY OF BACKGROUND DATA: Fifty-five patients participated in the survey. Mathematically describable phantoms were used to simulate the body of children of various ages. METHODS: Relative absorbed dose in the body was determined with measurements. The entrance surface dose and the dose-area product were measured for a number of patients. The effective dose and its variation between patients were estimated. RESULTS: The mean entrance surface doses were highest for the lumbar spine examinations (2.6 mGy, anteroposterior projection; 6.7 mGy, lateral projection). The female gonads received the highest dose. The mean entrance surface doses for the thoracic spine examinations were 2.1 mGy for the frontal view and 6.1 mGy for the lateral view. The breasts, thyroid, lungs, and esophagus received the highest absorbed dose. Mean effective dose for one frontal and one lateral view was slightly higher for lumbar spine examinations than for thoracic spine examinations. An optimized scoliosis examination gives a much lower effective dose, about 0.05 mSv (frontal view). If an additional exposure determining the "skeletal age" is performed, the effective dose rises with 0.12 mSv. CONCLUSIONS: Thoracic spine and lumbar spine examinations lead to relatively high-absorbed doses to radiation-sensitive organs. Because the scoliosis investigation is repeated several times, the total effective dose could be considerable.