Radiation dose reduction was a dominant theme at the 2008 RSNA scientific assembly.
If one point was clear to the nearly 60,000 people attending the meeting, it was that radiology has reasserted its authority over the use of ionizing radiation in diagnostic imaging.
Actions designed to shake radiologists from complacency about their application of x-rays in practice and new ideas for reducing dose appeared throughout the conference and show.
Reports from numerous hospitals suggest that radiologists are heeding calls to embrace radiation protection. Ultrasound and MRI utilizations have risen while the growth of multislice CT has slowed.
Yet many radiologists remain in the dark about basic things they can do to reduce patient exposure. Dr. Ella A. Kazerooni, a professor of cardiothoracic radiology at the University of Michigan, described results from the CT Awareness of Radiation Exposure Study, a web-based survey of 150 radiologists that measured their knowledge about CT radiation exposure and strategies known to reduce it.
Though 89% of radiologists were aware that reducing mA would reduce radiation exposure, Kazerooni was surprised that 11% were not aware of that common precautionary practice.
The survey found that 87% of respondents were aware of the value of reducing the kV setting during routine CT scans and 82% knew about progressive gating triggering to reduce radiation exposure during cardiac CT procedures.
The respondents believed, however, that they had limited access to most dose-reducing strategies. Only 61% said they could lower the mAs setting on their machines.
"I find it very sobering that 39% of radiologists didn't know that they could go to the scanner to reduce the mA," Kazerooni said.
Several studies suggest physicians have altered their behavior, however. Administrators at the Cincinnati Children's Hospital and the Children's Hospital of Philadelphia recently noticed a change in CT study volume.
The emerging trend led them to investigate whether increased awareness of CT radiation safety issues had actually affected utilization, said principal investigator Kevin E. Gessner, an assistant vice president of radiology and medical imaging at Cincinnati Children's Hospital.
Gessner and colleagues analyzed five years' worth of procedural data for CT, ultrasound, and MRI at both institutions and confirmed that CT use at the two hospitals was slowing.
Overall imaging utilization increased almost 6% during the five-year period because of more orders for ultrasound and MR. Fiveyear growth rates for MRI, ultrasound, and CT were, respectively 9.8%, 8.6%, and 1.6%. CT volume has fallen since 2007 while ultrasound and MRI volumes have increased by healthy percentages.
"We speculate that these trends, in part, represent the impact of education about radiation risks and a resulting reduction in unnecessary CT examinations and shift to non-radiation- generating procedures," Gessner said.
