Evaluating radiation doses in younger patients

Radiation doses during pediatric intervention procedures tend to be higher for younger patients and in the abdominal area, according to a recent study in the American Journal of Roentgetology.

Lead author Priscilla Lai of McMaster University in Hamilton, Ontario, and colleagues sought to determine effective dosing for imaging children during interventional radiology procedures.

According to the study, it is estimated that children are two to three times more sensitive to ionizing radiation than adults, and that developing high-sensitivity metal oxide semiconductor field effect transistor (MOSFET) dosimeters has led to their use in numerous other pediatric dosing studies. Lai and colleagues used an anthropomorphic phantom set and MOSFET dosimeters to determine estimates of effective dose for more complex pediatric radiology imaging techniques and suggested that these estimates can be used to infer the dose burden for clinical cases.

The team used the phantom set (ages 1, 5 and 10) and 20 MOSFETs inserted at radiosensitive organ locations. The phantoms were then exposed to mock head, chest, and abdominal radiology procedures performed with different magnifications—fluoroscopy, digital subtraction angiography (DSA) and spin angiography were simulated on each phantom.

The results found that doses from DSA, spin angiography and fluoroscopy were higher for younger ages because of the magnification use and were most significant for abdominal procedures.

Performing DSA of the head, chest and abdomen resulted in two to three times more dosage per minute than fluoroscopy.

Additionally, three to five frames of DSA meant an effective dose equal to one minute of flouroscopy and doses from spin angiography were almost half the doses from an equal number of DSA frames.

“Our results suggest that in situations requiring complex angulations to resolve overlapping structures, performing full spin angiography rather than separate DSA runs at various projections may result in some dose sparing,” the authors wrote.

The researchers added that a measure of effective dose can be used to estimate future malignancy risk associated with the dose received and they suggested dose sparing whenever possible.

“Patient doses during interventional radiology procedures vary significantly depending on the type of procedure but tend to be higher in younger children (because of the use of magnification) and higher in the abdomen,” they wrote. “It is important to be aware of opportunities for potential dose savings and implement when possible.”