Acta radiologica: therapy, physics, biology最新文献

The monosodium salt S-1-(2-hydroxy-3-amino) propylphosphorothioic acid (WR-77913) and S-2-amino ethylisothiuronium-Br-HBr (AET) were tested for protective effects against 4 MeV roentgen irradiation and fission neutrons in the mouse intestine. The parameters tested were intestinal crypt survival, lethality and intestinal crypt cellularity. The results showed both compounds to be good protectors in animals. The crypt survival curve for roentgen-irradiated mice treated with AET was parallel to that of the untreated group and was displaced to the right by 4.88 Gy (488 rad). Protection from neutron irradiation was less effective with a displacement of only 0.69 Gy (69 rad). Pretreatment with WR-77913 increased the slope of the crypt survival curve in roentgen-irradiated mice. This was also seen to a much less extent in neutron-irradiated animals. The displacements of the curves (at 50 per cent crypt survival) were found to be 5.15 and 1.02 Gy (515 and 102 rad) for roentgen and neutron irradiation, respectively. The lethality experiments showed a dose modification factor (DMF) of 1.42 for both drug-tested groups of roentgen-irradiated mice. The dose modification factors for fission neutron irradiated mice were 1.48 and 1.2 for WR-77913 and AET-treated mice, respectively. The effect of these protectors of crypt cellularity is also discussed.

The relative light output per Gy in water for conventional roentgen radiation (20-190 kV), high energy roentgen radiation (6 and 42 MV) and electrons between 2.2 and 34.5 MeV relative to 60 Co gamma radiation is reported for different kinds of LiF dosemeters. The routine use of LiF dosemeters for a wide range of dosimetry applications in radiation therapy, the handling of the dosemeters to obtain high accuracy and the usefulness of making patient dose measurements are described.

Groups of female CBA-mice were given 90Sr (14.8 kBq/g-0.4muCi/g--bodyweight) alone or in combination with polyestrodiolphosphate, methylprednisolone or nortestosterone, respectively. When 90Sr was given in the first combination, the frequency of osteosarcomas was significantly increased whereas the tumour latency time was decreased compared to mice given 90Sr alone. In combination with nortestosterone such effects were not found, whereas the combination 90Sr + methylprednisolone resulted in a strong reduction of the osteosarcoma incidence and a prolonged tumour latency time. The latter experiment was repeated in a larger experiment whereby the results were confirmed.

The build-up and build-down situation around air cavities of various size in a polystyrene phantom was evaluated by measurements with LiF-Teflon disks with a thickness of about 1.6 X 10(-2) kg/m2. The measurements demonstrate that when irradiating with two opposed beams the surface dose at the cavity (depth 39 mm) is 74% of the maximum dose for 60 Co, 77% for 6 MV and 87% for 42 MV roentgen radiation.

Twenty-three rabbits were exposed with 60Co irradiation over the skull. Nineteen of the animals received 29.6 Gy over the right hemisphere and 4 animals received 20 Gy over both hemispheres. Six months after the exposure the cncentrations of 5-hydroxyindolacetic acid (5-HIAA) and homovanillic acid (HVA) in seven different brain regions were assayed. No significant differences in the levels of these monoamine metabolites as compared to nonirradiated control animals were found. In contrast to discrete biochemical changes, a relatively marked parenchymal destruction was demonstrated by means of light microscopy, microangiography and scanning electron microscopy of the vessels, which exhibited telangiectases, fibrinoid necroses and thrombosis due to the late effects of irradiation.

In view of the close relationship which exists between image aberrations and the form of the transfer function, the transfer functions of some different types of spiral tomographic movements have been calculated numerically. The results allow prediction of a type of spiral movement which yields blurring of favourable quality. The validity of this approach has been demonstrated experimentally, by comparing the blurring characteristics of tomographs with single and multiple circular movements. When the radii of the circles in the latter case are chosen with reference to the form of the transfer function, a marked improvement in blurring quality is apparent.

The authors present the results of telecobalt therapy in 194 patients with malignant lung tumours treated between 1967 and 1971. The 3- and 5-year survivals were 9.7 and 5.4% respectively, with an average survival of 15 months. The results obtained depend on the microscopy, the clinical staging and on the irradiation techniques possible; several prognostic groups may be distinguished.

Pulmonary contraction, as measured by elevation of the right superior interlobar fissure, was investigated in 38 patients with carcinoma of the right breast, treated by radical mastectomy followed by irradiation with 60Co. Contraction of the right upper lobe was observed to extend over a minimum of four years although at a diminishing rate.

Of 36 patients with early carcinoma of the tongue treated with interstitial irradiation, 25 were controlled, 10 recurred and one developed local necrosis. Of 57 advanced cases treated with telecobalt therapy followed by interstitial irradiation, 15 were controlled, 20 recurred and 22 developed local necrosis. The frequency of necrosis following the combined irradiation was unacceptably high. Interstitial therapy alone may be a more adequate method for the primary tumour.