The detection of radionuclide activity in the living equine skeleton, using bone seeking radiopharmaceuticals and a hand-held radiation detector, is reported. Pathological changes in bone can be detected and subsequent development monitored. The availability and use of this diagnostic technique in equine practice is discussed.

A quantitative scanning method employing cyclotron-produced 52Fe has been developed to assess splenic erythropoiesis in patients with myeloproliferative disorders. In 12 patients with myelofibrosis splenic uptake of 52Fe was from 5.0% to 48% of the injected dose. Although a single patient with classical polycythaemia vera had a minor uptake of 2.8% of six other patients with this diagnosis showed no concentration of isotope in the splenic area. The fraction of 52Fe in the spleen of four patients with 'transitional' myeloproliferative disorders characterized by a high red cell mass, hypercellular bone marrow and a leucoerythroblastic blood film varied from 5% to 41%. No clear relationship was noted between the degree of splenic erythropoiesis as defined by this technique and the level of haemoglobin, the degree of splenomegaly, the effectiveness of erythropoiesis of traditional 59Fe surface counting. If splenectomy is considered in patients with myelofibrosis splenic 52Fe quantitation will provide more precise data on the contribution of splenic erythropoiesis than 59Fe surface counting alone.

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syNopsis The effect on the results obtained in surface counting investigations of using a dual detector counting system and multihole collimators has been investigated. The use of the additional detector results in smoother curves for the uptake of the radionuclide and the use of multihole collimators increases the discrimination of the counting system against the effects of radioactivity outside the region of interest. In a clinical trial to compare multihole collimation with conventional single hole collimation it was found that increased excess counts were obtained over the spleen with the multihole collimators in eight of ten cases.

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A method has been developed by means of which independent measurement can be made of the amount of red-cell destruction occurring in the spleen and the liver. The technique involves a standard red-cell survival study and surface-counting measurements together with quantitative scanning of the spleen and liver with 113mIn colloid in order to calibrate the surface counter. The rate of destruction in each organ is obtained by fitting the measured uptake curve for the organ to a theoretical uptake curve by computer. In addition, if whole body counting is also performed, the amount of red-cell destruction occurring in the rest of the reticuloendothelial system may be deduced. Results are given for measurements on a series of 11 patients.

South West England has the highest proportion of dwellings with private water supplies in the UK (3.6%) and most of these are also outside the urban areas and within the areas which have the highest probability of having high radon levels. The measurements presented demonstrate that a significant number of these dwellings are likely to have water supplies which exceed the NRPB's informal limit and also the WHO's reference level of dose. It is also possible that this latter limit may be exceeded for infants and children drinking water with radon concentrations below the NRPB's informal limit. In view of these results, it would seem prudent, particularly for dwellings with private water supplies in affected areas, to adopt an integrated approach to radon and to assess doses from all radon sources before determining the action to be taken when remedial measures are required. At the current time no significant central government funding is devoted to the problems arising from radon in water although there is a clear need both for a better understanding of the problem and for formal guidance on the level at which action should be taken to reduce radon concentrations in drinking water supplies.

There have recently been two publications in the Journal giving conflicting recommendations with regard to the necessity of making corrections to the simple measurement of divided renal function with 99Tcm DMSA for the different relative depth of positioning of the kidneys. Thus Nimmo et al (1987) conclude that it is not necessary to make corrections provided the supine projection is used and the upper border of one kidney is not below the mid-point of the other, while Wujanto et al (1987) recommend that both posterior and anterior views should be summed geometrically in order to correct for differing kidney positions within the body; they also find a much larger number of clinically significant discrepancies (greater than 5% difference) between the two methods than do Nimmo et al (22% as opposed to 7%).