Ionising radiation is extremely useful in many spheres that contribute to human health and the economy. Thus, it is appropriate in a modern, technologically driven country like South Africa to use radiation technology. It is also important, therefore, to maintain competence in the radiation sciences, including radiobiology, to ensure the effective and safe use of radiation. In medicine, radiation is extensively used in radiological procedures and more than half of all cancer patients in South Africa receive some form of radiotherapy. In addition, the country has nuclear power and a sophisticated nuclear industry served by a considerable number of personnel. It is, therefore, reasonable and desirable for the biological aspects of radiation, in addition to the physical radiation sciences, to be comprehensively addressed.

Radiobiology, as a science, has a major role to play in radiation research and academic development of the radiation sciences. Radiobiologists also have a critical role in training radiation workers in the various radiation-related disciplines, particularly in radiation oncology, which requires a good understanding of radiobiology. However, the number of radiobiologists in South Africa and worldwide is dwindling and has become too small to meet demand. Initiatives need to be started urgently to develop radiobiology and to increase the number of specialist radiobiologists in South Africa.

FIGURE 1: Location of centres of radiobiology within the South African radiation landscape.

It was soon discovered that X-rays could induce biological effects in tissue and it was not long before their application in the treatment of cancer became apparent. South Africa, once again, was quick to absorb the new technology and radium tubes were imported for this purpose as early as 1904.³In addition to radium treatments, X-ray machines were developed specifically for radiotherapy. Initial limitations were as a result of poor beam penetration into the body with the result that only superficial tumours could be treated effectively. After many years of use of these poorly penetrating X-ray machines, which often yielded severe skin reactions, the first megavoltage therapy units were introduced. These higher energy machines allowed effective treatment of deep-seated tumours. Cobalt units for radiotherapy were installed in South African radiotherapy departments in the late 1950s,³less than 10 years after the first cobalt treatments, which were delivered in Canada in 1951.⁴Subsequently, linear accelerators were introduced in South Africa in the 1970s. ³Today, IMRT (Intensity Modulated Radiotherapy) is common, with some centres now using the most modern image-guided radiotherapy equipment. Specialised radioactive implant treatments (brachytherapy) for specific sites including prostate, breast, eye and gynaecological tumours are also commonly employed.

Several particle accelerators have been developed in the country over the past 50 years and a number of cyclotrons are now in operation. The 1980s saw the development of particle radiotherapy at Faure near Cape Town with the building of the cyclotron at the National Accelerator Centre, now called the iThemba Laboratory for Accelerator-Based Sciences (iThemba LABS). Neutron and proton particle beams are available at this facility for treatment of cancer patients. In addition, research in several radiation sciences, including radiobiology, as well as isotope production, are undertaken at iThemba LABS.

Each stage of the evolution of diagnostic radiology and radiotherapy has appeared in South Africa since the discovery of X-rays and radioactivity, with well-developed infrastructure now present in all main centres. Nuclear medicine is no exception. Nuclear medicine was first conducted in South Africa in 1948 in Pretoria using imported isotopes,⁵and local accelerator-produced nuclides have been produced since 1955. ⁵Both SPECT (single photon emission computed tomography) and PET (positron emission tomography) imaging and hybrid imaging techniques, as well as therapeutic nuclear medicine, are now available in major South African cities.

When considering radiobiological effects in humans, medical radiation is by far the largest contributor to radiation exposure from human made sources.⁶Radiotherapy is a mainstay of cancer treatment with more than half of all South African cancer patients requiring some form of radiotherapy during their treatment.⁷Whilst radiotherapy delivers large cytotoxic doses of radiation to individuals during tumour treatment, imaging using ionising radiation is the fastest growing source of radiation exposure⁸and population risk. Notably, CT (computed tomography) scanning, notwithstanding its great benefits to diagnosis, is one of the major contributors to radiation dose and its associated carcinogenic risk to the population at large.⁸The invention of the CT scan was remarkably a South African contribution to medical imaging. The South African radiation scientist Allan Cormack, was awarded the Nobel Prize for Physiology or Medicine, together with Godfrey Hounsfield, in 1979 for conception of the CT scanner. The original concept was developed by Cormack while working at the University of Cape Town at Groote Schuur Hospital.⁹

South Africa’s nuclear industry originated in the 1940s with the creation of the Uranium Committee, and then later the Atomic Energy Board, and has been evolving and developing until the present day. South Africa’s nuclear weapons programme was developed under the apartheid government during the 1970s and then voluntarily dismantled in the 1990s.¹⁰In 1999, a parastatal, the Nuclear Energy Corporation of South Africa (NECSA), was instituted. Its role is to undertake research and development of peaceful uses of nuclear energy and radiation science and to process nuclear material.¹⁰NECSA operates the Safari-1 nuclear research reactor at Pelindaba, which is situated approximately 30 km west of Pretoria (Figure 1). The Vaalputs nuclear waste site situated approximately 600 km north of Cape Town (Figure 1) is also managed by NECSA.¹¹NECSA’s subsidiary, NTP Radioisotopes, is a leading international supplier of radioisotopes and radiopharmaceuticals. They are currently the world’s largest supplier of molybdenum-99,¹⁰a precursor of technecium-99, which is used extensively in nuclear medicine departments around the world.

South Africa also uses nuclear fuel as a source of energy. Approximately 5% of the country’s electricity comes from nuclear power¹⁰generated at the Koeberg Nuclear Power station near Cape Town (Figure 1), which has been in operation since 1985. There are plans for additional power reactors in the country.¹²

While limits for radiation exposure are prescribed, no exposure is completely safe and there is still some radiobiological uncertainty regarding human response to low doses of radiation. There is good evidence for a dose-effect relationship in the high dose region but it is necessary to extrapolate to estimate the risks at lower dose levels. Thus, there is some doubt as to the true relationship between low doses and the induction of biological effects. Several extrapolation models have been proposed, including the simple linear, the super-linear, linear quadratic and the hormesis models, as well as the possibility of a threshold below which no risk exists.¹⁵The linear no threshold model is often adopted by regulatory bodies in the interests of conservatism when defining radiation dose limits for human exposure. However, there is much debate as to the most appropriate models to use.¹⁶It is often assumed that any dose, no matter how small, carries some risk.

On an individual basis, risk from low-dose exposure may often be considered negligible but, when compounded for human populations, may contribute significantly to the number of radiation-induced cancers and genetic effects in the population at large and thus become a public health issue.

Whilst extensive use of medical radiation contributes to significant population exposures in everyday life, radiation can also affect human lives in times of accidental exposure or during natural disasters. The 2011 tsunami disaster at the Fukushima nuclear power station in Japan has highlighted the need for radiation preparedness and an understanding of the biological consequences of radiation. With extensive use of radiation, despite extensive safety measures being in place, accidents can and do happen. Recently, in South Africa, 91 workers at Koeberg nuclear power station were contaminated with radioactive material whilst performing maintenance.¹⁷Fortunately, the exposure levels were fairly low but such incidents do highlight the need for radiobiological collaboration in radiation safety planning, assessment and response to radiation accidents.

Radiobiology is important for radiation oncology research and practice. A detailed discussion of research areas in radiobiology is beyond the scope of this article, but an overview is provided in Table 1. Subjects range from the basic interactions of radiation with cells and tissues to the applied use of radiotherapy in the treatment of cancer.

With the increasing burden in Africa of non-communicable diseases such as cancer, radiotherapy will become increasingly relevant. It is thus important that some resources are directed towards South Africa’s own unique problems in this area. For example, compared with the developed world, many cancer patients in South Africa are diagnosed with advanced tumours, which may present particular radiobiological challenges. In addition, South Africa’s burden of infectious agents, such as HIV and human papillomavirus, may influence patient susceptibility to disease and response to therapy.

An understanding of the radiobiology of HIV and HIV-infected individuals is an area that presents an opportunity to make a contribution to the treatment of South Africans and others, particularly in Africa, who also are significantly affected by HIV. The high incidence of people with HIV (approximately 5.5 million South Africans in 2009¹⁸) means that many people in the country that are exposed to radiation also carry HIV, which has been reported to affect radiosensitivity.¹⁹Many people are also receiving antiretroviral therapy, which extends the lives of HIV-infected people, but which may also influence their radiation sensitivity. The implications for public health and radiation therapy are potentially large, as most radiation guidelines are based on international evidence-based protocols that were developed in populations that are largely free of HIV.

Another challenge facing radiobiologists in South Africa concerns radiobiology services in clinical radiotherapy departments. Radiobiologists can provide valuable input into treatment design and modification, as well as advice in a range of scientific aspects of clinical radiobiology. For example, treatment delays and interruptions frequently occur in South African radiation oncology centres. Long treatment waiting lists, poor patient compliance and interruptions for medical reasons as well as machine breakdown may compromise the success of radiotherapy, because extended treatments may allow, and even stimulate, tumour cell proliferation. Radiobiologists can provide solutions that compensate for treatment gaps and give advice about treatment protocols and tissue reactions. However, few South African radiation oncology departments have access to radiobiologists. Clinical radiobiology is a key area for development in South Africa, as well as in neighbouring states, where radiation oncology is expanding.

It would seem logical, given South Africa’s large radiation infrastructure, that there should be significant resources channelled into radiobiology as a basic science. The major universities should support radiobiology programmes to develop and maintain intellectual competence in the discipline. Yet this has not been the case. To some extent, radiobiology remains an orphan discipline which has failed to achieve a critical mass, yet is of immense relevance to a modern radiation-consuming society like South Africa. The number of radiobiologists currently employed in South Africa is at a critical level (Table 2) with approximately half within 10 years of retirement. This situation is unsustainable and needs to be addressed urgently.

Research and teaching activities were cultivated and, up until 2002, the radiobiological momentum produced over 20 postgraduate degrees from Stellenbosch University and the University of Cape Town, but none have been produced since. During this period, both of these institutions made significant international research contributions to the radiobiology of photons (X-rays and gamma rays) and published notable studies in areas such as dose-modifying drugs,^26,27repair,^28,29the oxygen effect, ^{30,31,32,33,34,35}metabolic modulation,³⁶damage response^37,38,39and biological dosimetry.⁴⁰

Regrettably, after 2000, the cutting of posts and poor prospects for graduates resulted in a sharp decline in radiobiology studies. The three once-thriving laboratories at Groote Schuur Hospital, Tygerberg Hospital and iThemba LABS continue with a much reduced capacity of only five remaining staff members.

Having described a once-vibrant era in radiobiology in the Western Cape followed by a period of contraction, it is fair to state that radiobiology has never been prominent in other regions of the country. Thus, despite pockets of activity nationally, radiobiology has not been well represented in South Africa as a whole. There are, as far as can be determined, no radiobiologists in any other African country.

It is important for South Africa to have scientists and other academics who are active in radiobiology and who can advise on matters pertaining to biological and health effects of radiation. As a scientific discipline, radiobiology both complements and draws from radiation oncology practice and research. Therefore, whilst radiobiology can exist as a science in its own right, its traditional partner has been cancer therapy, and, consequently, this is where it has found its main niche. An example of such a partnership is evident at Groote Schuur Hospital in Cape Town, where the Radiobiology Section is an integral part of the Department of Radiation Oncology.

Although radiation oncologists study radiobiology during their training, it is important to maintain appropriate depth and expertise in the subject, which can only be properly achieved through maintaining a strong specialist radiobiology presence in radiation oncology departments around the country. This importance is especially relevant for centres that provide radiation oncology training.

There are eight academic training centres for radiation oncology in the country (Figure 1) as well as an expanding private sector, which has grown significantly since the 1997 report of Levin and Goedhals³which gave an overview of radiation oncology in South Africa at that time. According to the International Atomic Energy Agency, there are 41 institutions within South Africa that offer radiotherapy. ⁴¹However, despite the extensive therapeutic irradiation of patients, the number of radiobiologists in the country is fewer than 10 (Table 2).

The roles of radiobiology in teaching, research and service to radiation medicine have become a logical fit. In addition to the academic programmes for radiobiologist training (Table 3), radiobiology forms a mandatory part of the curricula of many of the radiation-associated disciplines (Table 4). However, at present, non-radiobiologists frequently teach the subject out of necessity. Research is an important part of any science and is crucial if scientists are to remain current and relevant in their fields. Radiobiology services within clinical departments have also become increasingly necessary, as paradigms for cancer treatment planning are changing. For example, treatments may be optimised by the application of radiobiological models that may be incorporated into treatment prescriptions – such as Normal Tissue Complication Probability and Tumour Cure Probability models. As mentioned previously, others not trained or conversant in radiobiological principles have been inappropriately tasked with advising clinicians. This situation is obviously undesirable. The role of the professional radiobiologist requires specific competencies, as recognised by the Health Professions Council of South Africa (HPCSA), which distinguishes radiation biology as a medical science profession. Radiobiology responsibilities should thus be undertaken by qualified professionals.

In order to conduct scientific work related to human health or to provide advice that may have an impact on medical decisions, radiobiologists are required to register with the HPCSA. Initial registration as a trainee, formal competence and experiential training are required before full registration and practice as a professional radiobiologist in the medical environment is permitted. Training centres need to be accredited for this role. At present, no radiobiology training centres are accredited by the HPCSA. However, radiobiologists recognise the need for establishing future training and accreditation facilities and this need is currently being addressed by the South African Radiobiology Society (SARS).

For interested parties, a basic syllabus in radiobiology has been compiled by the International Atomic Energy Agency. ⁴²

Several publications have addressed the issue of radiobiology training for radiation oncologists outside South Africa. ^46,47,48In a recent survey by Rosenstein et al.⁴⁹, several conclusions were reached, which may in some ways echo the South African experience. In the USA, there is an aging cohort of radiobiologists (with an average estimated age of 52), who are responsible for passing on radiobiology knowledge. There is a similar trend in South Africa, albeit with a much smaller cohort. It was also noted that there was a disturbing decrease in the proportion of educators specifically trained in radiobiology and that many responsible for teaching radiobiology were not adequately versed in radiation science – only approximately 30% of the group were trained as radiobiologists. Rosenstein et al.⁴⁹recommended, on the basis of their findings, that radiobiology teaching resources be improved and they motivated for new radiobiology graduate programmes. Given that the situation is more extreme in South Africa, it follows that these recommendations should be equally relevant, if not more so, in this country.

While there is a place for short courses in radiobiology for registrars, short courses are not a substitute for proper teaching at the current training centres. Through necessity, because of the dearth of radiobiologists, short courses may be a stop-gap solution, but in the long term it is appropriate for academic centres to develop their own comprehensive radiobiology teaching platforms.

Universities need to embrace and promote radiobiology as an important academic discipline. Academic programmes must be created to train radiobiologists, create expertise and provide quality instruction in the subject for numerous other groups of radiation users. In order to do this, academic positions and laboratories must be created and research programmes initiated. It is reasonable that radiobiological education and training in radiation medicine and medical physics should be offered by specialist radiobiologists and that this condition should ideally become mandatory for accredited training centres.

The malady afflicting radiobiology is not unique to South Africa. The worldwide shortage of radiation scientists has been recognised in the USA and in Germany, where measures are already being taken to rectify this deficit. For example, the National Cancer Institute, which is part of the National Institutes of Health in the USA, is promoting a radiobiology education initiative in collaboration with US and international societies.⁵⁰In Germany, the need for a revitalisation in radiobiology has been recognised under the kompetenzerhaltung (maintaining competence) agenda.⁵¹This agenda has already led to new appointments and the creation of significant research infrastructure by the Bundesministerium fur Forschung und Technologie. Similar initiatives may also be appropriate in South Africa for radiobiology to achieve its own identity and profile in national planning. SARS is the professional society that promotes the interests and standards of the discipline in South Africa. As the representative body, SARS strongly recommends that the development of radiobiology is treated as a matter of national importance and urges politicians and administrators to incorporate the development of radiobiology into their future plans. It is clear that the reinvigoration of the discipline can only be achieved by collective will and effective lobbying and that this will be to the benefit of South African science.

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