Possibilities of increasing the value at depth of radiation from radium externally applied

The methods that generally are used for external application of radium are rather crude and unsatisfactory. This refers especially to the old “radium pack” where a number of radium containers are spread out over a big surface, which is placed at a certain distance from the skin (usually 4 to 10 cm. away). The disadvantages are:

1. It takes a great distance and a long time to get a depth dose comparable to the depth dose from X-rays produced by 200 K. V.

2. The protection is unsatisfactory and the weight is troublesome for the patient.

3. The distribution of the radiation is poor and the total amount of radiation absorbed by the whole body is many times (say 10 times) the amount absorbed by a cylinder or parallelopiped of tissue directly under the pack.

The attempt to eliminate these bad features has resulted in an apparatus which gives very little radiation outside the cylinder directly under the pack. The amount absorbed inside this cylinder is at least one half of the total amount absorbed by the whole body.

The following table gives a comparison between the effectivity of the two packs. The filter is for both 2 mm. of brass and 1 mm. of aluminum.