Soft Irradiation Research Articles

Effect of Different Lattice Defects on the Mobility of Dislocations in Alkali Halide Crystals

AbstractSingle crystals of KCl and NaCl are subjected to additive colouration treatment and X‐irradiation, and their hardening and softening observed. It is found that F‐centres and colloids have no appreciable effect on the mobility of dislocations. The assumption is made that certain defects are responsible for the hardening of irradiated NaCl crystals. These defects are due to soft irradiation and it is possible that they may be concerned with the generation of new vacancies during the irradiation.

Formation of Colour Centres in Undeformed and Deformed NaCl

AbstractRates of F‐centre formation and absorption spectra after soft and hard X‐irradiation and after subsequent bleaching were studied. Two stages of colouration are found. During the first stage, F‐centres are formed from vacancies present in the crystal prior to irradiation. The second stage during soft irradiation is attributed to the formation of F‐centres by a bulk mechanism; the second stage during hard irradiation, which is significant only in deformed crystals, is attribiuted to the formation of F‐centres from vacancy clusters generated by deformation.

Use and abuse of x-ray therapy for benign skin conditions with particular reference to x-ray atrophy.

It is the author's opinion that 500 r is the maximal safe total dose of ionizing radiation (half-value layer of 1.0 to 2.0 mm. of aluminum) in fractional doses at weekly intervals that should be given to the skin in treatment of a benign dermatosis; moreover, soft irradiation (grenz rays) will produce as good results in many dermatoses as standard superficial x-rays, with less risk of late sequelae. If a sharp and persistent erythema is produced by any single exposure, x-ray atrophy is almost certain to follow, even though it may be delayed for years. X-ray atrophy of the skin following treatment of a benign dermatosis is the most completely preventable of all serious human diseases.

Management of Angioma

<h3>To the Editor:—</h3> In the article "Management of Angiomas" inThe JournalOct. 15, 1960, Dr. D. J. Kindel relates his experience with soft and ultrasoft irradiation and concludes that this is the ideal treatment of certain infantile angiomas. There is no argument with his observation that the lesions respond to this therapy. Nevertheless, there are sound reasons why many radiologists and dermatologists refuse to use it. In the first place, the 15- and 20-year follow-up is more important than the 6-month or 1-year follow-up in these cases. If the patient acquires an area of skin atrophy or malignancy at the site of treatment 20 years later, neither she nor her family nor her doctor is going to be pleased. The author makes only cursory reference to late sequelae and states they can be avoided by "adequate equipment and training." He does not define this term; neither does he give

Low-voltage x-ray therapy in diseases of the skin.

BERYLLIUM tube x-ray units capable of delivering very soft irradiation have come into wide clinical use during recent years. Although a considerable number of reports on the effects of very soft x-rays on various diseases affecting the skin are available, interpretation of papers published prior to 1945-1950 is difficult. Older so-called grenz-ray units were relatively crude pieces of apparatus, with tubes of uneven wall thickness and inadequate means of controlling voltage and amperage precisely. Moreover, the calibrations of output from these units were made by methods which, on the basis of more recent physical studies, may be regarded as highly inaccurate. Great emphasis has been placed upon the relative safety of very soft irradiation. This emphasis is probably well justified in the case of x-rays generated at 6 or 8 kv.; in fact, if such rays are used in the treatment of skin having a thick layer of stratum