Organ-specific radiation dose rates and effective dose rates during percutaneous nephrolithotomy

Radiation exposure during medical procedures continues to be an increasing concern for physicians and patients. We determined organ-specific dose rates and calculated effective dose rates during right and left percutaneous nephrolithotomy (PCNL) using a validated phantom model.

A validated anthropomorphic adult male phantom was placed prone on an operating room table. Metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ locations in the model and were used to measure the organ dosages. A portable C-arm was used to provide continuous fluoroscopy for three 10 minute runs each to simulate a left and right PCNL. Organ dose rate (mGy/s) was determined by dividing organ dose by fluoroscopy time. The organ dose rates were multiplied by their tissue weighting factor and summed to determine effective dose rate (EDR) (mSv/s). Two-dimensional radiation distribution in the abdomen during a left-sided PCNL was visually determined using radiochromic film.

The EDR for a left PCNL was 0.021 mSv/s ± 0.0008. The EDR for a right PCNL was 0.014 mSv/s ± 0.0004. The skin entrance was exposed to the greatest amount of radiation during left and right PCNL, 0.24 mGy/s and 0.26 mGy/s, respectively. Radiochromic film demonstrates visually the nonuniform dose distribution as the x-ray beam enters through the skin from the radiation source.

The effective dose rate is higher for a left-sided PCNL compared with a right-sided PCNL. The distribution of radiation exposure during PCNL is not uniform. Further studies are needed to determine the long-term implications of these radiation doses during percutaneous stone removal.