Eye lens dose of medical personnel involved in fluoroscopy and interventional procedures at a Malaysian Hospital

Highlights

• The first report on the eye lens dose of medical staff working in fluoroscopy and interventional suite in Malaysia.

• KAP and fluoroscopy time are not good indicators of operators’ eye lens dose.

• Habitual positioning results in high radiation dose to interventionalists’ left eye lens.

• In-vivo radiation dose measurement is necessary to accurately evaluate operators’ eye lens doses.

Abstract

Objective

This study measured the radiation exposure of the eye lens of medical personnel performing fluoroscopy and interventional procedures at the Sarawak General Hospital in Kuching, Sarawak, Malaysia. This study was the first in Malaysia to utilise in vivo radiation measurement relatively near the eye lens.

Methods

41 medical personnel performing 79 procedures were monitored for their eye lens exposure using the NanoDot™ optically-stimulated luminescence dosimeters (OSLD) taped to the outer canthus of their eyes. The air-kerma area product (KAP), fluoroscopy time (FT) and number of procedure runs were also recorded.

Results

KAP, FT and number of runs were strongly correlated. However, only weak to moderate correlations were observed between these parameters with the measured eye lens doses. The average median equivalent eye lens dose was 0.052 mSv (ranging from 0.0155 to 0.672 mSv). The eye lens doses of primary operators were found to be significantly higher than their assistants due to the closer proximity to the patient and X-ray tube. The left eye lens of the operators received the highest amount of radiation due to their habitual positioning towards the radiation source.

Conclusion

KAP and FT were not useful in predicting the equivalent eye lens dose exposure in interventional radiological procedures. Direct in vivo measurements were needed to provide a better estimate of the eye lens doses received by medical personnel during these procedures.

This study highlights the importance of using direct measurement, such as OSLDs, instead of just indirect factors to monitor dose in the eye lens in radiological procedures.

Introduction

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has reported that around 3.6 billion radiological procedures are performed worldwide annually [1]. In diagnostic imaging, interventional radiological procedures, which are increasing in frequency and complexity incurs the highest radiation dose. Occupational exposure is defined as the radiation received in the course of work, except exposures excluded from the International Atomic Energy Agency (IAEA) Basic Safety Standard (BSS), and from practices or sources stated in the BSS.

Many studies on radiological exposure and its risk to health had been performed among radiology personnel and patients [2], [3], [4]. Recently, the occupational dose and the risk it posed to cardiologists had been highlighted [5]. These studies showed increased concern on the health effects for those exposed to radiation at work, particularly while performing complex procedures that might incur a higher dose [6], [7]. In Malaysia, an occupational exposure study in 2001 found that medical personnel received an average of 0.45 mSv [8] per year while performing procedures. Most studies used personal dosimeters to monitor body exposure, but few had focused solely on radiosensitive organs, such as the eyes and gonads [6], [7], [8], [9], [10], [11], [12].

In 2011, the International Commission on Radiological Protection (ICRP) revised its threshold dose for radiation-induced cataract formation to 0.5 Gy based on new epidemiology findings [13]. This led the commission to recommend that the annual equivalent dose limit for eye lens be reduced from 150 mSv to 20 mSv a year, averaged over a defined period of five years, with no single year exceeding 50 mSv. Following this revision, the IAEA had published a new safety guidelines for radiological procedures. The safety assessments included identifying ways that eye exposure could occur, determining the magnitude and likelihood of exposure in normal operations, and assessing potential exposures to a reasonable and practical extent [14].

We aim to determine the typical occupational dose on medical personnel, in particular the eye lens doses as they performed interventional procedures in the largest government hospital in Sarawak, Malaysia. To the best of the authors’ knowledge, this is the first publication documenting occupational dose in the country, with emphasis on the eye.