File:Megavolt x-ray machine - Los Angeles Inst of Radiology 1938.jpg

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Summary

Description	English: Million volt x-ray machine for radiotherapy built at Los Angeles Institute of Radiology, 1938. The x-ray tube itself is within the left column, while the right column is the transformer power source. The x-ray tube extends through the floor into the treatment room below. The toroidal metal electrodes along the porcelain columns are called corona caps. They equalize the potential gradient along the columns to prevent arcovers.
Date	April 1938
Source	Retrieved November 20, 2015 from "New Super-Power X-ray Installation" in Electronics magazine, McGraw-Hill Publishing Co., New York, Vol. 11, No. 4, April 1938, p. 36 on http://www.americanradiohistory.com/
Author	Unknown authorUnknown author
Permission (Reusing this file)	This 1938 issue of Electronics magazine would have the copyright renewed in 1966. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1965, 1966, and 1967 show no renewal entries for Electronics. Therefore the copyright was not renewed and it is in the public domain.

Licensing

This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.

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