Nearly half of pediatric oncology patients receive too much radiation

September 30, 2010
by Heather Mayer, DOTmed News Reporter
In order to better understand the benefit versus risk when it comes to medical imaging in children, researchers studied cumulative radiation dose (CRD) in pediatric patients, to find that more than 40 percent of pediatric oncology patients exceed the CRD threshold for risk of significant harm. The study was published online earlier this week in the October issue of Pediatrics.

The researchers found that the cumulative effectiveness radiation doses (CED) in pediatric oncology patients vary considerably.

Researchers from Canada retrospectively studied imaging histories of 150 pediatric oncology patients five years after diagnosis, who received treatment for leukemia, lymphomas, brain tumors, neuroblastomas and assorted solid tumors; there were 30 children in each subgroup.

All procedures that used ionizing radiation were studied, including radiography, computed tomography, nuclear medicine, fluoroscopy and interventional procedures.

The study found that CT and nuclear medicine were the greatest contributors to CED, with CT making up 30 percent of the procedures but 52 percent of the CED, and nuclear medicine making up 20 percent of the procedures and 46 percent of the CED. In the tumor subgroups, there was significant variability between groups.

In the five-year time period, the patients received a total of 4,338 imaging procedures involving radiation. CEDs varied greatly: 1.3 percent received CEDs of more than 500 mSv; 22 percent received CEDs of more than 200 mSv; and 41 percent received CEDs of more than 100 mSv. According to the Biological Effects of Ionizing Radiation, evidence suggests a risk of significant harm at the 100 mSv mark.

The researchers concluded that CEDs from imaging for pediatric oncology patients varied depending on diagnoses, individual clinical courses and imaging modalities used.

"The benefits of accurate, timely imaging are immense and must not be underestimated," the researchers wrote.

But because five-year survival rates for pediatric cancers exceed 80 percent for some tumors, the researchers said physicians need to "consider all possible sources of potentially harmful, long-term effects."