According to our results, the physician who performs prostatic artery embolization procedures, even with a ceiling suspended shield, would reach the annual radiation limit for the left eye with just one procedure per week, writes Gustavo Andrade, Recife, Brazil.
Prostatic artery embolization is a minimally invasive treatment of the obstructive symptoms of the lower urinary tract, secondary to benign prostatic hyperplasia. Embolization is slowly but surely gaining worlwide acceptance. Its efficacy is already proven and involved groups are now trying to improve its safety. There is also the important aspect of radiation exposure to be considered. We need to minimise radiation exposure as a way to improve the results of embolization.
We prospectively analysed 25 consecutive prostatic artery embolization cases using direct and indirect measures to evaluate patients’ and radiologists’ exposure. We placed a radiosensitive film designed to measure the peak skin dose under the patient’s pelvis. The interventional radiologist wore nine pairs of very small dosimeters strategically positioned (eyes, glabella, thyroid, chest, hands, knees and feet) that could measure effective and equivalent dose to organs and tissues. Cone beam CT (CBCT) was available and used only when the interventional radiologist judged it to be necessary, not routinely. We found that even when used, the CBCT was the source of less than 10% of the radiation. Digital subtraction angiography was responsible for 71.45% and fluoroscopy for 19.9% of the radiation.
There are very few data available in the literature regarding radiation exposure with prostatic artery embolization. In a few papers, only indirect measures such as fluoroscopy time and dose area product, both easily extracted from the equipment at the end of the procedure, were available. In the largest series (Pisco 2016) with CT angiography previously performed in all 630 patients, the fluoroscopy time was low (19.5 minutes) but the dose area product was high (2,415Gy.cm2) showing that fluoroscopy is not the main source of radiation, and that the equipment needs adjustments in order to respect the ALARA (As low as reasonably achievable) principles.
Our dose area product (450.7Gy.cm2), while amongst the lowest in all series reported (that had at least 10 patients), still represent values above those reported in other complex interventional procedures. This can be explained due to the high number of digital subtraction angiography runs and images obtained in different oblique views to understand the anatomy of the very thin prostatic arteries. The average equivalent dose found for the left eye was 0.378mSv. After several studies reporting a significant increase in radiation-associated eye lens opacities and cataracts among interventional physicians, the International Commission on Radiological Protection (ICRP) reduced the annual limit for equivalent dose for lens of eyes to 20mSv. According to our results, the physician who performs prostatic artery embolization procedures, even with a ceiling suspended shield, would reach the annual limit for the left eye with just one procedure per week.
In the light of this data, we invited the engineer of the imaging system (Siemens) and arrived at a radiological protocol for prostate artery embolization where we are working with about 30% of the dose obtained with the standard protocol. These data will be published soon.
Gustavo Andrade is professor of Radiology in FCMCG and director of Angiorad, Hospital Santa Joana in Recife, Brazil. He has reported no disclosures pertaining to this article.