IR radiation dose comes under scrutiny

Directives to decrease radiation exposure have galvanized researchers in Belgium to start a multicenter study to assess patient doses in interventional radiology. The data could lead to future auditing parameters.

Twenty centers throughout Belgium are participating in this ongoing project, which is concentrating on angiography of the lower limbs, said Dr. Kristien Smans from the University Hospital Leuven.

Data are gathered through extensive interviews with interventionalists regarding working procedures, verification of data in at least 10 patient cases, registry of dose area product (DAP) values during one year, and physical and technical tests of equipment.

DAP values that were corrected for patient weight were used to set national diagnostic reference levels. Smans and colleagues studied the influence of different parameters on the DAP value. Initial results indicate large intra- and intercenter variations in DAP value per procedure, Smans said during a Monday afternoon scientific session.

The variations are partly due to different system parameters such as dose levels at the image intensifier. But, mainly, they result from the different ways that interventional radiologists and staff work.

"Some centers take three times as many frames during fluoroscopic procedures as others," Smans said. "The variation is very wide."

This variation isn't necessarily a call for punitive action, however. High patient doses could be due to different pathologies or different body mass indexes, she said.

The researchers want to gather enough data to establish a normalized baseline. It would then be possible to give feedback to centers that deviate from the standard. A series of guidelines for the optimizations of interventional procedures could be derived as well.

For now, the investigators conclude that it is possible to select a minimal data set for interventional procedures that allows a directed feedback for future auditing.

Another part of this project involved placing thermal luminescent dosimeters on the hands, lower legs, and foreheads of interventional radiologists to estimate dose. Again, physicians at different centers showed a wide variation, Smans said.

"The differences among radiologists are amazing because they're doing the same procedure," Smans said.