Safety Assessment and Quality Control of Medical X-Ray Facilities in Some Hospitals in Ghana

GH9800015 TECHNICAL REPORT, 1997 SAFETY ASSESSMENT AND QUALITY CONTROL OF MEDICAL X-RAY FACILITIES IN SOME HOSPITALS IN GHANA E.O.DARKO AND D.F. CHARLES RADIATION PROTECTION BOARD GHANA ATOMIC ENERGY COMMISSION P. O. BOX 80 LEGON 29-39 a. TECHNICAL REPORT, 1997 SAFETY ASSESSMENT AND QUALITY CONTROL OF MEDICAL X-RAY FACILITIES IN SOME HOSPITALS IN GHANA E. O. Darko and D. F. Charles Radiation Protection Board Ghana Atomic Energy Commission P. O. Box 80 Legon, Accra. ABSTRACT Safety assessment and quality control measurements of diagnostic x-ray installations were earned out in five Hospitals in Ghana. The study was focused on the siting, design and construction of the buildings housing the x-ray units, assessment of safety systems and devices and measurements of the technical performance, and film processing conditions. The location, inadequacies in the design/construction, unavailability of relevant safety systems ar.d devices, violation of basic safety principles and poor performance of some of the x-ray faciliiies indicate the need to improve quality control programmes, safety culture and enforcement of regulatory standards in diagnostic x-ray examinations in Ghana. 1. INTRODUCTION Medical application of x-rays constitute the greatest source of man-made radiation exposure in Ghana. It is estimated that x-rays in diagnostic examinations contributes about 90% of all man- made sources [1], Data collected between 1988-94 show that the mean annual collective effective dose due to x-ray examinations in Ghana is about 252 man mSv i.e. 0.014:Sv per capita per year [2]. The frequency of the x-ray examinations vary remarkably from one Hospital to the other. Available statistics show that radiation risk factors have increased in recent times [3-5]. Poor image processing conditions, deficiencies in the performance of some of the x-ray machines have been some of the contributory factors leading to poor contrasts in x-ray photographs. Violation of basic safety principles and multiple x-ray examinations have also led to overexposure of both patients and the x-ray technicians in an attempt to improve image quality. To institute controls and enforce regulatory standards in order to minimize doses to both patients and the x-ray worker, there is the need to ensure effective quality control programme, and adequate radiological protection and safety in the x-ray departments. This report presents a survey conducted in five hospitals in Ghana. The survey focused on the safety in siting, design and construction of the x-ray departments and measurements of some technical parameters of the x-ray machine. This is with a view to assist in the improvement of radiological safety in the X-ray Departments of the Hospitals. 2. MATERIALS AND METHODS 2.1 Quality Control Quality control measurements were carried out in five Hospitals in the Brong-Ahafo, Eastern, Volta and the Greater Accra Regions. The measured units consisted of conventional diagnostic x- ray units with bulky tables and chest stands. The generators were different models of Siemens, Toshiba and ERAF. The technical parameters and exposure measurements were performed with a radiation monitor MONITOR 4™ equipped with an ionization chamber, and Victoreen model 4000M+ multifunction meter. Film processing conditions were tested using an RMI dual colour sensitometer X-Rite model 334 and RMI 331 B/W transmission densitometer. Films were developed according to the method used in the Hospitals. The films used in the Hospitals were mainly KODAK, MACO-x-ray, Valca and AGFA Curix. 2.2 Safety Assessment Safety assessment was carried out with respect to the siting, structural shielding, adequacy of room space and availability of safety systems and devices. The assessment of the type and extent of barriers required to protect the workers and the general public depends on the output factors of the x-ray machine, and use and occupancy factors. 2.2.1 Siting The location of the x-ray department was assessed with respect to its proximity to outpatient and emergency wards as well as the relative occupancies of adjacent areas to the x-ray room. The occupancy factor is the fraction of the treatment time for which a particular area is likely to be occupied. The occupancy factors for primary barriers are designated thus: T = 1 for the floor; T = 1/4 for the walls; and T < 1/4 for the ceiling. For work areas such as offices, laboratories, shops, occupied areas in nearby buildings, living quarters, and so on, we assign T = 1 for full occupancy. Corridors, rest rooms, unattended parking lots, elevators with operators, etc are assigned T = 1/4 for partial occupancy. Waiting rooms, toilets, unattended elevators, pedestrian walks and vehicular traffic, etc. are assign occupancy factor of T = 1/16 for occassional occupancy [6]. 2.2.2 Structural Shielding and Design Ths integrity of the walls of an x-ray room and extent of other primary barriers depend on the output parameters of the x-ray machine being used. An ideal x-ray room has a minimum room space of 25m2 and workload of 50% for chest x-ray examinations, 30% for Abdomen, Pelvis and spine and 20% for skull and extremeties examinations [6,7]. Scattered radiation measurements were performed with the x-ray tube oriented in the horizontal and vertical directions, representing the most common types of examinations e.g. chest and abdomen respectively. Dose rates at different positions in the x-ray room and behind the doors and walls outside the x-ray room were measured using the radiation monitor MONITOR 4™. 2.2.3 Safety Systems and Devices Safety systems such as warning signs, warning lights and interlocks as well as the safety devices used to protect patients, operators, radiologist and parents/people who help some patients were inspected. The safety devices include gondal shields, lead rubber gloves, lead aprons, lead glasses and radiation protection doors or lead protective barriers. 3. RESULTS AND DISCUSSIONS Tables 1 and 2 show the number of radiological units and the reported number of common x-ray examinations in the sample hospitals. Three of the hospitals serve large communities within the various regions. In two of the hospitals, namely Manna Mission and Methodist Church hospitals, the x-ray units have not yet been installed. In the V. R. A. hospital, only the conventional x-ray unit is functioning. The fluroscopy and dental units are yet to be put into operation. Quality control parameters measured to determine the performance of the x-ray units are provided in tables 4-6. The accuracy of the exposure parameters, namely, the reproducibility of the radiation exposure parameter, x-ray tube voltage and the exposure time partially meet the recommended limit of 5%, 10% and 15% respectively[8]. These show that the units are not performing consistently as required. Film processing condition and range of film processing parameters are shown in tables 7-8. It should be noted that the temperatures of the processors (developer, fixer and washer) are significantly higher given rise to high thermal fogging of the films. The characteristic curves of film processing in some of the hospitals is shown in figure 1. The curves indicate clearly the differences in the performance of the processing parameters. Most of the processing conditions indicate a high base and fog, and low maximum optical density. These conditions results in poor image quality and consequently leading to overexposure of patients in an attempt to improve on the image quality through multiple x-ray examinations. The conditions may be improved by using high speed film-screen combinations and high quality film processing. The cost and benefit for such improved processing conditions would be tremencvus. Additionally, quality assurance measures should be established to maintain high level of quality. The mean doses in adjacent areas around the x-ray rooms are provided in table 9. Most of the values measured are below the minimum detectable limit of 0.2(iSv/hr for the dose rate meter used, especially for V. R. A. hospital. This indicate the quality of construction of the walls of the x-ray room with respect to scatter radiation. Scatter radiations were detected at the main entrance to the x-ray room, the wall behind the chest stand, the radiographer's office and parts of the patients waiting area in some of the hospitals. These show that there are no lead doors and the structural shielding of the walls are inadequate. They can also be observed from the design of the various protective barriers given in table 10. From table 10, it can also be seen that with the exception of V. R. A. and Manna Mission hospitals, the windows of the main x-ray rooms are low level even though these rooms are located in high occupancy areas. Some of the hospitals do not also have adequate safety devices as exemplified in table 11. Figures 2-6 show the layout of the x-ray departments for the various hospitals. Some of the x-ray units are located within full occupancy in supervised areas with only that of the V. R. A. situated within an isolated area of the hospital complex. CONCLUSION The safety assessment and quality control measurements revealed the need to establish and maintain an effective quality assurance programme in the x-ray departments of the hospitals. Basic Quality Assurance (QA) test devices such as densitometer, sensitometer radiation monitor, kVp meter and image quality test devices could be provided for routine QA programme. Additionally, conditions in the x-ray departments need to be improved with appropriate orientation of x-ray beam in order to reduce scatter radiation to occupied areas of the x-ray departments. These should be of priority when considering the cost and the benefit to improve image quality and reduce doses to patients and the occupational workers.

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