Age-dependent evaluation of organ and effective doses in pediatric full-spine radiography: influence of anteroposterior and posteroanterior projection and copper filtration using Monte Carlo simulation.

BACKGROUND

Repeated full-spine radiography for scoliosis follow-up in children results in increased radiation exposure, especially to anterior radiosensitive organs. Optimizing projection direction and beam filtration is essential for dose reduction.

OBJECTIVE

To quantitatively evaluate the age-dependent effects of anteroposterior (AP) and posteroanterior (PA) projections, with and without a 0.1-mm copper filter, on organ and effective doses in pediatric full-spine radiography.

MATERIALS AND

METHODS

Monte Carlo simulations were performed using the Particle and Heavy Ion Transport code System with 5-, 10-, and 15-year-old female hybrid phantoms. Full-spine radiography from the first cervical vertebra to both femoral heads was modeled under AP and PA conditions, with or without copper filtration. Organ doses were calculated, with active bone marrow and bone surface evaluated using the "International Commission on Radiological Protection Publication 116" dose response functions. Percentage depth dose analysis was performed to assess the effect of body thickness.

RESULTS

PA projection markedly reduced doses to anterior radiosensitive organs, with maximum reductions of approximately 93% for the breast (AP/PA ratio 14) and over 80% for the thyroid. Copper filtration provided additional reductions of 15-19% in AP and 5-6% in PA. In contrast, dose increases were observed in posterior and deep-seated organs such as the kidneys and active bone marrow. Effective dose was reduced by about half with PA and further decreased with copper filtration.

CONCLUSION

PA projection and copper filtration are effective strategies for reducing radiation exposure to anterior radiosensitive organs and lowering effective dose in pediatric full-spine radiography. However, dose increases in deep-seated organs were also observed, highlighting the need for protocol optimization according to patient age and organ location.