Because young children are more sensitive to radiation than adults, pediatric nuclear medicine providers need to have at least a basic understanding of radiation risk and dosimetry, as well as know how to effectively communicate this information to patients and their families, according to an article published in the March issue of the Journal of Nuclear Medicine Technology.
Frederic H. Fahey, ScD, and colleagues from the department of radiology at Harvard Medical School in Boston, explained that a review of health insurance records for more than 350,000 children in the U.S. showed that 42.5 percent had at least one radiologic exam over the three-year study period. On average, a child will receive seven radiologic exams by the age of 18, with the most common procedure being plain radiograph, but the number of CT and nuclear medicine studies is increasing.
With the high volumes and increased attention being paid to radiation dose in the media, it’s important for pediatric imaging providers to understand the risks and how they affect younger patients specifically.
“The radiopharmaceutical dose to children varies from that to an adult for several reasons, particularly the patient size. The absorbed fractions and organ masses of children differ from those of adults because the organs of children are smaller and closer together,” wrote the authors.
Using CT dose as an example, Fahey and colleagues wrote that dose indexing done on acrylic phantoms has shown that dose to a newborn is approximately twice that to a medium-sized adult for the same CT acquisition parameters. Radiopharmaceutical doses vary similarly between pediatric patients and adults.
Risk from ionizing radiation varies with both age and sex. The authors explained that children are more radiosensitive because they are actively growing and have a longer life span than adults, meaning there is longer time for the risks to be realized. Girls have a nearly 50 percent higher risk of cancer induction because of the excess risk of breast cancer.
As the general public continues to show an increased interest in radiation risks, Fahey et al wrote that “It is more important than ever that nuclear medicine practitioners—including physicians, physicists, technologists, and other members of patient care teams—be able to effectively communicate with their physician colleagues and with patients and families about the medical use of radiation, the level of radiation exposure, and its potential risk.” To assist in these explanations, providers can lean on resources from the “Image Gently” campaign developed by the Alliance for Radiation Safety in Pediatric Imaging, which includes a number of professional societies.
All members of a nuclear medicine clinic need to be able to answer questions, and issues of dose risk need to be discussed as a team ahead of time so that patients and their families receive consistent answers, according to the authors. Patients likely have little background information to understand quantitative measurement terms such as millisieverts, so risk should be talked about in common terms. For instance, dose received from a nuclear medicine procedure may be comparable to one year’s worth of background radiation.
The authors also touched on ways to reduce dose administered to pediatric patients and emphasized a study should only be performed if it is appropriate to the clinical question being asked. “Advances in instrumentation also may facilitate reducing the administered activity,” they wrote. “For example, with dual-detector rather than single-detector SPECT systems, the administered activity can be reduced.”