II. Depth Dose Data and Diaphragm Design for the Saskatchewan 1000 Curie Cobalt Unit

A 20 Curie Telecobalt Unit

“…The 'F' factor is obtained directly from the inverse square law (MAYNEORD and LAMERTON, 1941). JOHNS, Epp, CORMACK and FEDORUK (1952) have already confirmed this prediction for source-skin distances between 50 and 100 em. We have made an attempt to extend their investigations to smaller values of s.s.d.…”

Radiation Distribution from a 1,000 Curie Cobalt Unit Using Conventional and Rotation Techniques

“…Cobalt-tumor distance 80 cm. 6.5 field at a source to tumor distance of 80 em. On the left-hand side is a distribution obtained using two 5 X 5 90°wedge fields.…”

“…The Saskatoon Cobalt 60 Unit The Saskatoon Unit (4,5,6,9) contains a Cobalt source I" in diameter and 1/2" thick, containing approximately 1,000 curies of Cobalt. This source gives an output of about 30 r/min.…”

“…To minimize the' size of the penumbra, the limiting diaphragm should be placed near the skin surface. However, if it is placed close to the skin surface electrons scattered from the lead diaphragm greatly increase the skin dose (6) and destroy the skin sparing effect of Cobalt (1). We have found that placing the diaphragm 15 to 20 em from the skin is a reasonable compromise between penumbra effects and skin saving effects.…”

“…In the original design, collimation was achieved by a number of replaceable lead diaphragms 5 to 8 em thick (6), to which were fastened suitable compression cones. The system is satisfactory, but suffers from some disadvantages.…”