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Although high-energy electrons have been used in 'therapy for many years, little still seems to be known regarding the effect of irregularities of human anatomy on the dose distribution. When such irregularities are due to bodies of limited width, then perturbations of the normal dose distribution, as seen in homogeneous tissue, may cause eith'er small areas of overdose (hot spots) or areas of underdose (cold areas). The former may be large enough to damage vital organs or to develop necroses; the latter may allow tumour cells to survive treatment and thus lead to recurrence. These assumptions have constantly worried therapeutists and physicists. To calculate the effect of irregularities by theoretical means seems a tedious approach, the effect being dependent on the geometrical dimensions of the perturbing structures. The application of the Monte Carlo technique would be a time-consuming task even for a single case. The present

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~yoinetrial (Morris ct al. 1955) and choriodecidual (Browne 1958) circulation have been demonstrated, by radioactive methods, to slow down in toxaemia. In toxaemic patients the arteries of the ocular fundus show spasticity. This is presumed to be the case with the pelvic arteries also, although it has not yet been adequately demonstrated. Clemetson (1960) and Gordon and McKay (1964) examined the pelvis of postpartum patients with severe toxaemia by arteriography and found aortal hypoplasia; they presume that this is of importance as an aetiological factor in toxaemia. Crottogini et al. (1964) found, by arteriography during pregnancy, considerable sclerotic deformation of rhe aorta and narrow uterine arteries in one patient.The present authors wished to throw additional light, by pelvic arteriography, on the path~physiological condition of the arteries in toxaemic patients during pregnancy and to devote special attention to the relationship of the diameters of uterine arteries and aorta. The work was based on the assumption that the uterine arteries might show a spasticity similar to that in the arteries of the ocular fundus. Should this assumption prove correct, fresh prospects would perhaps be opened up for both surgical and drug treatment of toxaemia. The presacral sympathectomy, carried out by Clemetson on five patients with aortal hypoplasia, of whom three later became pregnant, produced promising results. Only one of the three developed a mild pre-eclampsia, although her earlier pregnancies had resulted in an early onset of toxaemia and intra-uterine death of the foetus. 86