Cumulative radiation dose from medical imaging procedures in patients undergoing resection for lung cancer

Radiation dose from diagnostic imaging procedures is not monitored in patients undergoing surgery for lung cancer. Evidence suggests an increased lifetime risk of malignancy of 1.0% per 100 millisieverts (mSv). As such, recommendations are to restrict healthcare and radiation workers to a maximum dose of 50 mSv per year or to 100 mSv over a three-year period. The purpose of this study was to estimate cumulative effective doses of radiation in patients undergoing lung cancer resection and to determine predictors of increased exposure.

We identified 94 consecutive patients undergoing resection for non-small cell lung cancer. Radiologic procedures performed from one year prior to resection until two years postresection were recorded. Estimates of effective doses (mSv) were obtained from published literature and institutional records. Predictors of dose greater than 50 mSv per year and greater than 100 mSv per three years were examined statistically.

The majority of patients (median age = 67 years) had stage IA cancer (52%). In the three-year period, patients had 1,958 radiologic studies (20.8/patient) including 398 computed tomographic (CT) scans (4.23/patient) and 211 positron emission tomography (PET) scans (2.24 per patient). The three-year median estimated radiation dose was 84.0 mSv (interquartile range, 44.1 to 123.2 mSv). The highest dose was in the preoperative year. In any one year, 66% of patients received more than 50 mSv, while 19% received over 100 mSv. Over the three-year period, 43.6% of patients exceeded 100 mSv. The majority of the radiation (89.8%) was from CT or PET scans. On multivariate analysis, a history of previous malignancy (odds ratio [OR] 3.8; confidence interval [CI] 1.14 to 12.7), postoperative complications (OR 6.16; CI 1.42 to 26.6), and postoperative surveillance with PET-CT (OR 13.2; CI 4.34 to 40.3) predicted exposure greater than 100 mSv over the three-year period.

This study demonstrates that lung cancer patients often receive a higher dose of radiation than that considered safe for healthcare and radiation workers. The median cumulative dose reported in this study could potentially increase the individual estimated lifetime cancer risk by as much as 0.8%. Although risk-benefit considerations are clearly different between these groups, strategies should be in place to decrease radiation doses during the preoperative workup and postoperative period.