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Radiologists Receive Limited Radiation Exposure While Performing CT-Guided Percutaneous Radiofrequency Tumour Ablation: Presented at RSNA

By Ed Susman

CHICAGO, IL -- November 30, 2007 -- Radiologists who perform percutaneous radiofrequency ablation procedures using computed tomography (CT) to guide the way to the tumour are not being exposed to excessive amounts of radiation when they use normal precautions such as working behind leaded windows.

At the 93rd Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA), researchers presented the results of a study that evaluated radiation exposure to operators involved in interventional CT fluoroscopy performed in patients with solid tumours.

"Real-time guidance that is fast and accurate is provided by use of CT fluoroscopy," said Thomas Caramella, MD, Radiologist, Centre Hospitalier Université de Nice, Nice, France. "However, there is a potential that frequent procedures could expose doctors to more than the maximum [safe] level of exposure a year."

Levels of radiation considered to be safe are no more than 20 mSv/year to the whole body, 500 mSv/year to the hands, and 150 mSv/year to the feet, Dr. Caramella said.

Dr. Caramella said that to reduce radiation exposure, researchers in France are developing an alternative to continuous CT fluoroscopy. The new procedure is called "stop and shoot" fluoroscopy or the "quick-check technique", used to assure accurate placement of the radiofrequency ablation needles into the tumour. Instead of a continuous radiation exposure, the alternatives only produce fast contiguous slices.

In his study, presented orally on November 29, Dr. Caramella assessed the radiation exposure to the procedure operators involved in interventional CT without CT fluoroscopy performed in patients with solid tumours in which there was no ultrasound target.

The operators wore eight radiation detectors and worked close to the patient -- about 1 m away -- behind a hanging lead window. The operators also wore lead aprons.

The operators worked on 24 patients, treating 20 liver tumours, two lung tumours, one kidney tumour, and one retroperitoneal tumour. During the procedure, between one and 54 CT slices were taken to provide enough accuracy to perform the percutaneous procedures.

"The operational real-time electronic dosimeter found that exposure to the operator was less than 0.1 mSv in all cases," Dr. Caramella said. "CT guidance with the step and shoot technique without using CT fluoroscopy is a safe procedure that doesn't deliver any significant dose to the radiologist performing a radiofrequency procedure."


[Presentation title: Radiologist Dosimetry of Percutaneous CT-Guided Radiofrequency Treatment of Solid Tumors. Abstract SSQ08-02]

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