Radiation distribution in a private neurological theatre during invasive back pain management procedures

Abstract

The aim of the study was to determine radiation dose levels around the theatre table, on either side of the C-Arm, in order to establish if the radiation dose received by staff during back pain procedures fell within the limits set by the International Commission of Radiological Protection (ICRP). The question that arose from this goal was whether the stance of staff, in relation to the x-ray tube side of the C-Arm, influenced radiation dose levels. In order to apply the ALARA principle, the possibility of lowering the radiation dose in the neurological theatre was explored.

The measurement methodology of the study was twofold: measurements were executed by means of TLD meters, as well as with an ionisation chamber. TLD meters were placed on the patient, the neurosurgeon and the radiographer during back pain procedures, and, more specifically, during fluoroscopy, to record the doses with the Image Intensifier (II) above the table as well as with the x-ray tube above the table, at the pelvis and the chest height of the staff. Ionisation chamber measurements were recorded in 25cm intervals around the theatre table with a phantom and the C-Arm positioned in the PA, oblique and lateral positions at 110cm and 133cm heights from the floor.

The TLD results indicated that, when compared to the Image Intensifier side, the radiation dose was higher on the x-ray tube side of the C-Arm. The radiation dose was higher at the height closest to the x-ray source. The radiation dose received by the patient was higher with the x-ray tube positioned above the table (PA). The radiation dose to the surgeon’s hand and body was higher with the x-ray tube positioned above the table (PA). Radiation dose levels with the x-ray tube above the table during back pain procedures in the current theatre exceeded the occupational annual recommendation of 500mSv to the neurosurgeons hands, as recommended by the ICRP. The opposite is true with the II positioned above the table. The research question was answered positively in that the x-ray tube under couch orientation has the potential to limit dose levels during back pain procedures.

The measurement values resulted in a proposed protocol in terms of positioning of staff and orientation of the C-Arm in order to apply the ALARA principle during back pain procedures. Constant revision of protocols is the responsibility of the radiographer in order to guarantee that the ALARA principle is implemented in every unique situation.