J. J. Fletcher

ASSESSMENT OF RADIOFREQUENCY RADIATION WITHIN THE VICINITY OF SOME GSM BASE STATIONS IN GHANA

A radiofrequency (RF) electromagnetic radiation safety survey had been carried out at public access points in 46 towns with 76 Global Systems for Mobile communication cell sites in two major cities in Ghana. The objective was to determine the levels of RF field in residential areas, schools and market places, and compare the measured results with the guidelines set by the International Commission of Non-Ionising Radiation (ICNIRP). Measurements were made with log-periodic antenna coupled with spectrum analyzer. The results varied from 0.85 to 1.07 mW m(-2) and 0.78 to 1.19 mW m(-2) for the transmission frequencies of 900 and 1800 MHz, respectively. The result generally shows a compliance with the ICNIRP limit of 0.024 % but was 108 times higher than a similar survey carried out in Ghana 2 y ago.

Measurement and analysis of radiofrequency radiations from some mobile phone base stations in Ghana.

A survey of the radiofrequency electromagnetic radiation at public access points in the vicinity of 50 cellular phone base stations has been carried out. The primary objective was to measure and analyse the electromagnetic field strength levels emitted by antennae installed and operated by the Ghana Telecommunications Company. On all the sites measurements were made using a hand-held spectrum analyser to determine the electric field level with the 900 and 1800 MHz frequency bands. The results indicated that power densities at public access points varied from as low as 0.01 microW m(-2) to as high as 10 microW m(-2) for the frequency of 900 MHz. At a transmission frequency of 1800 MHz, the variation of power densities is from 0.01 to 100 microW m(-2). The results were found to be in compliant with the International Commission on Non-ionizing Radiological Protection guidance level but were 20 times higher than the results generally obtained for such a practice elsewhere. There is therefore a need to re-assess the situation to ensure reduction in the present level as an increase in mobile phone usage is envisaged within the next few years.

Quality Assurance and Quality Control of Equipment in Diagnostic Radiology Practice-The Ghanaian Experience

The World Health Organization (WHO) defines a quality assurance (QA) programme in diagnostic radiology as an organized effort by the staff operating a facility to ensure that the diagnostic images produced are of sufficiently high quality so that they consistently provide adequate diagnostic information at the lowest possible cost and with the least possible exposure of the patient to radiation: (World Health Organization [WHO], 1982). The nature and extent of this programme will vary with the size and type of the facility, the type of examinations conducted, and other factors. The determination of what constitutes high quality in any QA programme will be made by the diagnostic radiology facility producing the images. The QA programme must cover the entire X-ray system from machine, to processor, to view box. Quality assurance actions include both quality control (QC) techniques and quality administration procedures. QC is normally part of the QA programme and quality control techniques are those techniques used in the monitoring (or testing) and maintenance of the technical elements or components of an X-ray system. The quality control techniques thus are concerned directly with the equipment that can affect the quality of the image i.e. the part of the QA programme that deals with instrumentation and equipment. An X-ray system refers to an assemblage of components for the controlled production of diagnostic images with X-rays. It includes minimally an X-ray high voltage generator, an X-ray control device, a tube-housing assembly, a beam-limiting device and the necessary supporting structures. Other components that function with the system, such as image receptors, image processors, automatic exposure control devices, view boxes and darkrooms, are also parts of the system. The main goal of a QC programme is to ensure the accuracy of the diagnosis or the intervention (optimising the outcome) while minimising the radiation dose to achieve that objective In a typical diagnostic radiology facility, QC procedures may include the following: a. Acceptance test and commissioning Acceptance test is performed on new equipment to demonstrate that it is performing within the manufacturer’s specifications and criteria (and also to confirm that the equipment meets

Medical physics practice and training in Ghana

Medical physics has been an indispensable and strategic stakeholder in the delivery of radiological services to the healthcare system of Ghana. The practice has immensely supported radiation oncology and medical imaging facilities over the years, while the locally established training programme continues to produce human resource to feed these facilities. The training programme has grown to receive students from other African countries in addition to local students. Ghana has been recognised by the International Atomic Energy Agency as Regional Designated Centre for Academic Training of Medical Physicists in Africa. The Ghana Society for Medical Physics collaborates with the School of Nuclear and Allied Sciences of the University of Ghana to ensure that training offered to medical physicists meet international standards, making them clinically qualified. The Society has also worked together with other bodies for the passage of the Health Professions Regulatory Bodies Act, giving legal backing to the practice of medical physics and other allied health professions in Ghana. The country has participated in a number of International Atomic Energy Agencys projects on medical physics and has benefited from its training courses, fellowships and workshops, as well as those of other agencies such as International Organization for Medical Physics. This has placed Ghanas medical physicists in good position to practice competently and improve healthcare.

Assessment of levels of occupational exposure to workers in radiofrequency fields of two television stations in Accra, Ghana

A survey of the radiofrequency (RF) radiation was undertaken within the premises of two television (TV) stations, TVA and TVB, in Accra, Ghana. The primary objective of this study was to determine the level of RF exposure to workers in the TV stations. A spectrum analyser, a bi-conical antenna (30-300 MHz) and a log-periodic antenna (200 MHz-2.0 GHz) were used. Results obtained indicated that the wideband electric field strength levels recorded in this work vary between 0.006 and 58.5 V m(-1) at TVA and between 0.007 and 28.5 V m(-1) at TVB. Compared with the results from TVB, TVA recorded relatively higher values in the 30-400 MHz range, whereas TVB produced relatively higher values in the 400 MHz-1.7 GHz range. Generally, results obtained were found to be below the occupational reference levels of the International Commission on Non-Ionizing Radiation Protection, but at some locations, the field intensity was 4.3 times higher than the reference levels for the general public.

Investigation of the status of occupational radiation protection in Malawian hospital

Background The main objective of this study was to explore the occupational radiation protection program in three hospitals in Malawi and discover how radiation protection measures for workers are being implemented in their radiology departments. Method A questionnaire was administered to heads of X-ray departments for Kamuzu Central Hospital, Bwaila Hospital and Mtengo wa Nthenga Hospital to investigate occupational radiation protection practices in their departments. Results The study discovered that hospitals lack radiation protection programs which covers a number of critical issues including quality assurance and personnel dose monitoring. Conclusion The implementation of basic elements of occupational radiation protection in Malawian hospitals is inadequate.

Radiation dose assessment for occupationally exposed workers in Malawi

Background The objective of this study was to assess individual doses received by radiographers, and the scattered radiation dose rate reaching the control panel in X-ray departments of three hospitals in Malawi, in-order to compare them against the internationally recommended limits. Methods Themoluminescent Dosimeters were issued to fifteen (15) radiographers to record their dose for a month. Dose rate measurements were recorded using survey meters. Results Average monthly dose for workers was 0.247mSv. Average ambient dose rate values were 0.39µSv/hr for Mtengo wa Nthenga Hospital, 5.03µSv/hr for Bwaila Hospital and 4µSv/hr for Kamuzu Central Hospital. Conclusions Dose levels are below the limits recommended by the International Commission on Radiological Protection (ICRP).

ASSESSMENT OF THE INTEGRITY OF STRUCTURAL SHIELDING OF FOUR COMPUTED TOMOGRAPHY FACILITIES IN THE GREATER ACCRA REGION OF GHANA

The structural shielding thicknesses of the walls of four computed tomography (CT) facilities in Ghana were re-evaluated to verify the shielding integrity using the new shielding design methods recommended by the National Council on Radiological Protection and Measurements (NCRP). The shielding thickness obtained ranged from 120 to 155 mm using default DLP values proposed by the European Commission and 110 to 168 mm using derived DLP values from the four CT manufacturers. These values are within the accepted standard concrete wall thickness ranging from 102 to 152 mm prescribed by the NCRP. The ultrasonic pulse testing of all walls indicated that these are of good quality and free of voids since pulse velocities estimated were within the range of 3.496±0.005 km s(-1). An average dose equivalent rate estimated for supervised areas is 3.4±0.27 µSv week(-1) and that for the controlled area is 18.0±0.15 µSv week(-1), which are within acceptable values.

Optimisation of patient radiation protection in conventional X-ray imaging procedures using film reject analysis: a demonstration of the importance of rare earth screen-film systems.

The optimisation of patient protection was studied using a conventional film screen of speed class 200 and a rare earth film screen of speed class 400. The entrance surface dose (ESD) for the two film-screen systems was determined for patients undergoing some common diagnostic procedures (chest, lumbar spine and pelvis series). The ESD was the optimising parameter and its trade off with the image quality assessment of the radiographs. The estimated ESDs were compared with reference levels set by the Commission of the European Communities for a typical standard adult patient. A mean dose reduction of 17-33 % was achieved upon adoption of a rare earth film screen of speed class 400. Regular assessment of patient dose, quality control (QC) of parameters that affect the patient dose and image quality, adoption of faster rare earth screens and optimum radiographic technique are recommended in order to achieve optimisation goals.

The Effect of Rare Earth Screen on Dose Reduction for Conventional Imaging Procedures

By introduction of rare earth film-screen combinations of speed class 400 instead of classical film-screen combinations of speed class 200, dose reduction has already been possible. By this study the extent of dose reduction without loss of clinical information in conventional imaging procedures for patients undergoing simple radiographic examinations (chest, lumbar spine and pelvis series) was to be examined by comparing conventional film-screen to rare earth film-screen. The entrance surface dose (ESD) for conventional film-screen combination of speed class 200 was compared with that of rare earth film-screen combination of speed class 400. Upon the adoption of rare earth screen of speed class 400, a dose reduction of 33% for chest, 17% for lumbar spine and 28% for pelvis examinations was achieved. A change of the film-screen system to faster systems such as rare earth, consistent with the imaging requirements of the examination is recommended in our diagnostic departments.