Teletherapy Design Problems

The Race For Megavoltage X-Rays Versus Telegamma

“…1952, with an activity of 876 curies. and a specific activity of 25 curies/g ( 161). Records at M.D.…”

“…Also, Dr. Grimmett had planned to use uranium shielding in the cobalt head, but due to wartime restrictions, he had to switch to the tungsten alloy Hevimet, which was hard as diamond and difficult to machine. ORINS obtained the cobalt-59 wafers, and they were inserted at Chalk River in June, 1950, along with the two Canadian sources (Johns' and Eldorado's) (24,65,151,161).…”

“…In July of 1950 the final contracts were completed and signed between UTMDA and ORINS and between UTMDA and G E (155,161). In July Dr. Fletcher presented a paper in Paris at the Fifth International Cancer Congress detailing the design and operation of the unit (151, 162, 163).…”

“…which had been sent from Milwaukee to ORINS, was loaded with a 200 curie source loaned back to the AEC by Dr. Max Cutler of the Chicago Tumor Institute (65,151). With this source the unit delivered 15.5 r/min at 50 cm SSD for a 15 x 15 cm field (159,161).…”

“…Finally in July, 1952. the USA source, now at 876 curies, was released from Chalk River to ORINS (65,161). Fourteen months of testing at ORINS ensued.…”