Assessment and Optimization of Occupational Radiation Doses in Fluoroscopy Guided Procedure at Korle - Bu Teaching Hospital, Accra, Ghana

Abstract

International Commission on Radiological Protection (ICRP) publication 85 of 2000 recommended the use of two dosimeters for the monitoring of staff performing fluoroscopically guided procedures. This study aimed to assess the dose to operators performing fluoroscopically guided procedures at Korle – Bu Teaching Hospital and evaluate possibility for dose reduction. Four Radiologists, the Interventional Radiologist and the assistant were monitored for a period of one month and four Cardiologists were monitored for two months. Two electronic dosimeters were used by each worker present in the room and the personal equivalent dose Hp (10) and Hp (0.07) were recorded after each procedure. The Kerma Area Product (KAP) and screening time were also recorded per procedure. The scattered radiation dose rate was measured using a water phantom at 1 m from the focal spot, 160 cm from the floor at 0°, 90°, 120° and 180° for 3 projection of the tube (RAO 30°, LAO 30° and AP 0°). The patient dose and screening time at Radiology Department (over couch tube) were [1.89 - 14.38] Gy.cm², (0.2 -2.5) min; [3.76 – 44.16] Gy.cm², (0.3 – 3.1) min and [8.7 – 60.77] Gy.cm², (1.9 – 10.9) min for Retrograde Urethrogram (RUG), Hysterosalpingography (HSG) and special cases respectively. The patient dose and screening time range at Cardiology (under couch tube) were [14.24 – 120.61] Gy.cm², (1.7 – 16.3) min, [42 – 237] Gy.cm², (9.70 – 43) min and [4.37 – 33.56] Gy.cm², (4.30 – 11.8) min for Coronary Angiogram (CA), Percutaneous Coronary Intervention (PCI) and Right Heart Catheterization (RHC) respectively. The dose range per procedure to Cardiologists was [0.1 – 42.15] μSv, [1.2 – 31.2] μSv and [0.1 – 2.75] μSv for the CA, PCI and RHC respectively. The range of the estimated monthly effective dose, and eye lens dose to Cardiologists and Radiologists were [0.01 – 0.07] mSv, (0.15, 0.30) mSv and [0.03 – 0.12] mSv, (0.53 – 3.39) mSv respectively. The interventional procedures were found to be lengthier with exposure time of (52 – 76.4 min), and delivered relatively high dose (47.13 – 412.23 Gy.cm²) to patients. The Interventional Radiologist and the assistant received an effective dose of 0.09 mSv, 0.03 mSv respectively and eye lens dose of 1.2 mSv, 0.33 mSv respectively. A weak but significant relationship (R² = 0.32, p-value < 0.05) was found to exist between patient dose and staff effective dose, meaning that staff dose is influence by other factors. Generally, the staff effective dose and eye lens dose to Cardiologists and Radiologists were below the acceptable limits (1.67 mSv/month) excerpt for one Radiologist whose eye lens dose exceeded the limit by a factor of 2. Therefore, the use of a ceiling suspended screen is highly recommended in radiology to reduce the eye lens dose. Monte Carlo simulation of the distribution of radiation in the room highlighted the safest position that can be occupied by the staff as dose reduction technique to reduce the dose. The Implementation of the proposed radiation safety programme is encouraged for optimization of protection in both departments.