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Nuclear medicine caught the wave of development of medical imaging technologies. Thus in Australia, the late 1960s and early 1970s w a s the

"honeymoon period" for nuclear medicine according to the Foundation President of the Australian and N e w Zealand Society for Nuclear Medicine (Lander, 1972).

Interest w a s growing a m o n g doctors, other professionals, hospital administrators, the general public, politicians, and private enterprise. The media w a s giving

"considerable time and space" to nuclear medicine. "Charitable Foundations" and community organisations d u g deep to finance nuclear medicine units, and s o m e

"outstanding" contributions c a m e from "altruistic individuals". Whatever the motives, there w a s also s o m e corporate benefaction - for example Searle

Nucleonics donated a g a m m a camera for clinical research. In the two years to 1972 the n u m b e r of nuclear medicine g a m m a cameras in Australia rose from two to fifteen and there w a s also a marked rise in the n u m b e r of rectilinear and

conventional single-headed scanners. (Lander, 1972.)

The earliest uses of medical radioisotopes were therapeutic (and often iatrogenic) - radioisotopes supplied energy rather than information. Until imaging

equipment w a s developed from the 1950s, nuclear medicine w a s limited to either therapeutic procedures or diagnostic tests of function and flow which generally required sampling body tissues and fluids to determine the distribution of radioactivity, or alternatively the use of simple external counters to detect and quantify radiation levels. Diagnostic procedures gradually became the most frequent application of nuclear medicine. Within the field of diagnostic nuclear medicine, tissue sampling and external quantitative scanning gave w a y to nuclear imaging. This w a s facilitated by the development of increasingly sophisticated scanners, research into radiopharmaceuticals which localise in specific organs, and computer technology. (Ganatra and Nofal, 1986; M c R a e , 1963.)

Rectilinear scanners were the first pieces of equipment used for nuclear imaging.

These scanners, introduced in the late 1940s, gradually gave w a y to g a m m a cameras from the late 1950s. Both w o r k o n the s a m e principle - activation by radiation striking a crystal, usually a sodium iodide crystal. H o w e v e r g a m m a cameras produce a film without having to scan the patient physically, they can be used for dynamic studies whereas rectilinear scanners cannot, and they give superior resolution to rectilinear scanners, (van Herk, 1986; Ganatra and Nofal,

1986; Boyd and Lane, 1973; Lull and Littlefield, 1993.) B y the end of the 1960s, g a m m a cameras were being produced on a commercial scale, often by the same companies involved in the development of equipment for other imaging modalities. A range of increasingly sophisticated imaging cameras has been introduced based on the sodium iodide scintillation crystal - the rectilinear scanner, the g a m m a camera, the whole body imager or multicrystal scanner, and the single photon emission computed tomographic (SPECT) scanner. (Hamilton, 1982, pp.19-25.) The development of g a m m a cameras significantly expanded the range of applications of nuclear medicine; similarly, the n e w generation of

g a m m a cameras, particularly those equipped with S P E C T , resulted in a resurgence of nuclear medicine in the 1980s. (Carretta, 1993; Hamilton, 1982, p.35.)

Major advances in computer data acquisition and analysis also took place from the late 1960s, with significant implications for nuclear medicine. (Croft, 1990;

Dugdale, 1974; Flakus, 1981.)

Radioisotope production technology underwent considerable growth and development from the 1960s. Reactor radioisotope production involves reactor irradiation facilities, post-irradiation handling and processing (mechanical and chemical), measurement, dispensing, packing, and transport. Innovations took place across the spectrum of these activities. The development of a wider range of radiopharmaceuticals, along with freeze-dried radiopharmaceutical kits which required a m i n i m u m of preparation at the hospital, facilitated the growth of

nuclear medicine; n o longer w a s it confined to large hospitals with direct access to a radiopharmacy. Such innovations have also facilitated the gradual spread of nuclear medicine to private clinics. (Khafagi, 1992.)

The development of a number of generator systems was particularly important, with the desired radioisotope being "milked" from the longer-lived parent

radioisotope at or close to the point of use; this meant that transport time and distance w a s less of an obstacle. Technetium-99m, d r a w n from Mo-99/Tc-99m generators, became established as the most c o m m o n diagnostic imaging radioisotope. This entailed research and development across a range of areas -H E U target technology, target processing, generator technology, and conjugation of Tc-99m with a range of molecules to produce an ever-wider range of Tc-99m

radiopharmaceuticals. Whereas in the formative years of nuclear medicine

doctors would take whatever radioisotopes they could get, Mo-99/Tc-99m became the radioisotope of choice and supply of this radioisotope became increasingly important. (Stelson et al., 1995; W e b b , 1988, pp.10-12; Egan et al., 1994.) Although Tc-99m rapidly became the dominant radioisotope for diagnostic studies, the range

of radioisotopes used in nuclear medicine increased considerably; s o m e important developments were the use of gallium-67 from 1969, thallium-201 (1975), and

fluorine-18 (1979). (Egan et al., 1994; Khafagi, 1993.)

Whereas the development of other imaging modalities depended primarily on the symbiotic interests of manufacturing companies and doctors, the symbiosis in radioisotope production and supply w a s between public-sector nuclear agencies and doctors. A consequence of this w a s that financial interests were not nearly so important as with other imaging modalities, as indicated by the supply of

radioisotopes free of charge. Over the decades this has changed, through two main processes. U n d e r the impact of economic rationalism, nuclear agencies have commercialised radioisotope production and marketing. The practice of supplying radioisotopes at no cost became less frequent though there remains a considerable degree of subsidisation. Secondly, private companies have played an increasingly prominent role in the radioisotope industry.

From the early post-war years a pattern was set in relation to the involvement of private companies in the radioisotope industry. The pattern w a s (and is) for

nuclear agencies to produce radioisotopes and private radiopharmaceutical

companies to assume intermediary roles - processing , packaging, transport, and finally supplying radioisotopes to hospitals. This pattern remains the n o r m today.

The radiopharmaceutical companies are involved in, or have links to, the

pharmaceutical industry, and they generally supply hospitals with radioisotopes and pharmaceuticals or with pre-mixed radiopharmaceuticals. The

radiopharmaceutical companies have significantly affected the radioisotope industry in a n u m b e r of ways. They have played a role in product research and thus increased the n u m b e r of products being used in nuclear medicine. They have consolidated and expanded the market for medical radioisotopes, in the process securing nuclear medicine's place within the field of diagnostic imaging. They have developed global supply chains: domestic producers increasingly find themselves in competition with foreign suppliers. They act as a significant constituency for public-sector radioisotope production (except w h e n it competes with their o w n radioisotope production operations). A n u m b e r of

radiopharmaceutical companies o w n and operate cyclotrons dedicated to

radioisotope manufacture, and s o m e of the larger companies have begun to play a greater direct role in reactor radioisotope production in the past decade.

As well as the movement of radiopharmaceutical companies into radioisotope production, they have also assumed m o r e of the functions previously carried out in hospitals and n o w supply doctors with ready-to-use doses of

radiopharma-ceuticals. In short, the divisions within the industry - bulk radioisotope production (nuclear agencies), intermediary processing and transport

(radiopharmaceutical companies), and final processing (hospitals) - have become far less neat.

The growth of a number of imaging modalities has slowed over the past 10-20 years. At the broadest level this has been a consequence of economic forces, with capitalist economies moving in and out of recession. There has been less

opportunity for the development of n e w imaging modalities, with the cost of developing n e w advanced systems having increased considerably. Market

saturation has occurred with s o m e modalities, forcing s o m e companies out of the imaging industry. Another check on the growth of imaging modalities has been cut-backs in government funding for R & D , and the various methods used by governments to limit health-care spending, with expensive technologies being an obvious target.

Radioisotope production has not been affected in the same way as other aspects of the medical imaging industry, for reasons such as the primacy of public-sector

nuclear agencies in radioisotope production (and their partial immunity from market forces), and the need for ongoing radioisotope supply which m a k e s market saturation less of a problem in comparison with imaging equipment. Neverthe-less radioisotope production has felt the squeeze. Despite the fact that most of the 60+ countries to have operated research reactors have used them for radioisotope production, a m o n g other purposes, the commercial export trade has always been far more concentrated. There are m a n y reasons for this, such as the modest size of the world radioisotope market and the inadequacy of m a n y research reactors for production of high specific activity radioisotopes. In the early 1990s the

concentration w a s such that a Canadian c o m p a n y supplied almost all of world d e m a n d for Mo-99; if there had been protracted problems with that operation there could have been a major worldwide shortage of Mo-99/Tc-99m.

The Research Reactor Review (1993, p.91) neatly summed up the current, messy situation in the radioisotope industry. It said that the global radioisotope market is in a very dynamic state, and there is no certainty h o w things will change. All aspects of supply, logistics, usage, and price are in flux. Enough reactors exist to supply or even over-supply the market depending on priorities of reactor usage.

The Review said that the one predictable variable is that d e m a n d for radioisotopes will increase, but even that is questionable in the m e d i u m to long term as will be discussed in chapter seven.