Varying lengths of the cervical spinal cord of @entity35 were irradiated with single doses of X rays. Dose-related changes in the latency for the development of @entity912 , or for the presence of histological lesions in the spinal cord, indicated a dependency on the length of spine irradiated. The dose associated with a specified latency increased as the field size was reduced from 16 mm to 4 mm. A more precise indication of the importance of field size came from a determination of the ED50 values for @entity35 developing @entity912 in less than 30 weeks of irradiation or from those that showed neurological signs, or histological evidence, of irradiation damage, occurring after latent periods of greater than 30 weeks. These end-points were primarily related to @entity62 and gross vascular damage respectively. For @entity912 in greater than 30 weeks the ED50 increased markedly from 21.5 +/- 0.3 Gy for a 16 mm field to 50.98 +/- 2.28 Gy when a 4 mm length of cord was irradiated. For @entity455 only a small change in ED50 value was found, from 20.0 +/- 0.5 Gy to 25.58 +/- 2.78 Gy for 16 mm and 4 mm fields respectively. At less than or equal to ED25 no evidence for a field-size effect was seen for this late lesion. These results were examined in the light of some old and some more recently analysed clinical data for radiation @entity602 . It is hoped that this will initiate other investigations in this important area of radiotherapy practice.

The influence of field size on the late tolerance of the XXXX spinal cord to single doses of X rays.

@entity455 :: ('MESH:D014652', 'Disease') :: ['vascular lesions'] @entity602 :: ('MESH:D013118', 'Disease') :: ['myelopathy'] @entity35 :: ('10116', 'Species') :: ['rats'] @entity62 :: ('MESH:D056784', 'Disease') :: ['white-matter necrosis'] @entity912 :: ('MESH:D010243', 'Disease') :: ['paralysis']
@entity35 :: (10116,Species) :: ['rat']
