Cardiovascular Journal of Africa: Vol 32 No 5 (SEPTEMBER/OCTOBER 2021)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 5, September/October 2021 272 AFRICA hands and feet of staff in a reproducible and affordable way. Even though the staff in this specific cardiology theatre were issued with personal radiation-protection monitoring devices (dosimeters), an urgency to have an estimate of effective radiation dose to the hands, feet, thyroid and eyes was identified. Physicists are not permanently employed at all hospitals and monitoring thermoluminescence crystal dosimeters (TLDs) are not available in all hospitals for projects, so therefore the possibility of measuring the doses with finger dosimeters was explored. The aim of this study was to determine the safety culture among relevant members of staff involved in cardiovascular imaging procedures, in order to communicate recommendations to enhance the safety culture where applicable. The staff around the interventional table are mostly exposed to scatter radiation, but with certain techniques and protective devices, the effective dose can be below the set dose limits. 2 As a rule, the interventionalist and scrub nurse are close to the X-ray source and because of the location, may receive up to 1 000 times more radiation than the radiographer and technologist behind the barrier in the control room. 2,9 Distance is a valuable approach to limiting dose since radiation dose decreases as the square of the distance between the radiation source and the operator increases (the inverse- square law). Operators must continuously consider moving away from the X-ray source, especially during injection of the contrast media with a mechanical injector. 2 The stance of the operator in relation to the image receptor (II) side of the equipment must also receive meticulous attention. In general, scattered radiation is most intense on the entrance beam side of the patient. It is therefore best practice for the interventionalist to be placed on the II side during a lateral projection, facing the tube. 10 Furthermore, the positioning of the X-ray equipment should receive careful consideration, bearing in mind the complexity of using more than one C-arm simultaneously. Angulation of the tube plays a significant role in reducing the dose. For example, the standard view for the left mainstem coronary artery (left anterior oblique with 60°/–20° angulation) is associated with a 7.6-fold increase in dose to the operator and a 2.6-fold increase in dose to the patient, in comparison to an alternative less- frequently used angulation (caudal postero-anterior 0°/–30°). 11 Shielding that can be used comprises architectural shielding, equipment-mounted shields and personal protective devices, including lead aprons, lead glasses and thyroid shields. 12 The practical advice to limit radiation dose is therefore available but implementation of the principles of distance, time and shielding needed confirmation for a specific cardiovascular site. Methods The application of distance, time and shielding principles was regarded as an indication of the safety culture of the specific cardiovascular site. The research design involved a prospective, descriptive case study. 13 Aquantitatively designed radiation safety-culture audit checklist (Table 1) 14–17 and a dosimetry provider dose report (Table 2) were used to observe the general safety culture among cardiology staff and to measure the radiation dose to the eyes, thyroid and feet of nine individual staff members. The radiation safety-culture audit checklist was benchmarked and compiled to include the summary of recommendations for occupational radiation protection in cardiology procedures from several societies. 1,2,15,18 The checklist was used to observe and check (tick) the criteria on the list. The checklist was divided into four headings, namely (1) distance; (2) time and techniques; (3) shielding; and (4) monitoring. The criteria that were observed to evaluate the general radiation-safety compliance of the site were all arranged under these headings (Table 1). The distance of the feet was measured from the X-ray tube under the theatre bed. The distance was measured between the dorsum of the foot closest to the tube to the top part of the tube from where the beam emerges, using a tailor’s measuring tape (Table 3). The effective dose to the eyes, thyroid, hands and feet of the participants was measured with TLDs. In order to be reproducible and standardised, the TLDs were ordered from the South African Bureau of Standards (SABS), which is the radiation protection service provider (RPS) in South Africa, to explore the practical use of this type of measurement. The research setting was the cardiology unit of a public- sector hospital in South Africa. For anonymity, the name of the hospital is not disclosed. Ethical approval for the research project was obtained from the Health Sciences Research Ethics Committee of the University of the Free State in Bloemfontein, South Africa (UFS-HSD2018/0780/2509). Participants in the cardiology theatre signed written consent forms to be observed and to wear the dosimeters. Table 1. Radiation safety-culture audit checklist, with areas of non-compliance indicated by the shaded cells Distanc e2,1 7 Time and techniques 2,17 Shielding 1,2 Monitoring Distance of feet from the X-ray source (refer also to the foot pedal) Intermittent screening Thickness of shielding lead aprons, thyroid shields (mm Pb) All radiation workers dosimeters Hand in main X-ray beam Last image hold Lead glasses How many dosimeters per person? Elbow in main beam Loop image replay 15 Lead glasses: protective sides If only one dosimeter – outside at collar level without eye protection? 16 C-arm angulation: limit steep gantry (more than 30°) 11 Fluoroscopy duration Head cover 17 Consistent wearing Orientation of C-arm (tube under couch) Pulsed fluoroscopy Table screens 1,12 Staff informed regarding personal dose During mechanical injection all staff move away from table Pulsed rate frame/s Ceiling screens 1,12 Anaesthetist further than 1 m from the patient Dose area product Hand screens 1,12 Door closed during procedures Collimation and filter utilisation Table 2. Dosimetry report: finger dosimeter readings for 11 procedures Staff member Cumulative TLD dose (mSv) Eye Thyroid Foot Hand Cardiologist 0.45 0.25 0.48 0.73 Nurse 0.54 0.35 0.52 0.65 Floor nurse 0 0 0 0 Radiographer 0.22 0.42 0 0 TLD, thermoluminescence crystal dosimeter; mSv, millisievert.