Cumulative Radiation Dose From Medical Imaging Procedures in Patients Undergoing Resection for Lung Cancer
ABSTRACT 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.
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ABSTRACT: The aim of this study was to evaluate oncologists' opinions about the use of ionizing radiation in medical imaging of oncology patients. An electronic survey was e-mailed to 2,725 oncologists at the top 50 National Cancer Institute-funded cancer centers. The survey focused on opinions on CT dose reduction in oncology patients and current philosophies behind long-term imaging in these patients. The response rate was 15% (415 of 2,725). Eighty-two percent of respondents stated that their patients or families have expressed anxiety regarding radiation dose from medical imaging. Although fewer than half of oncologists (48%) did not know whether CT dose reduction techniques were used at their institutions, only 25% were concerned that small lesions may be missed with low-dose CT techniques. The majority of oncologists (63%) follow National Comprehensive Cancer Network guidelines for imaging follow-up, while the remainder follow other national guidelines such as those of the Children's Oncology Group, the American Society of Clinical Oncology, or clinical trials. Ninety percent of respondents believe that long-term surveillance in oncology patients is warranted, particularly in patients with breast cancer, melanoma, sarcoma, and pediatric malignancies. The majority of oncologists would consider the use of low-dose CT imaging in specific patient populations: (1) children and young women, (2) those with malignancies that do not routinely metastasize to the liver, and (3) patients undergoing surveillance imaging. Cumulative radiation exposure is a concern for patients and oncologists. Among oncologists, there is support for long-term imaging surveillance despite lack of national guidelines.Journal of the American College of Radiology: JACR 12/2013; 11(5). DOI:10.1016/j.jacr.2013.08.018