Shielding for scattered radiation to the testis during pelvic radiotherapy: is it worth?

To assess the value of external shielding of the testis during pelvic radiotherapy.

Nineteen patients, receiving radiotherapy to the pelvis with the lower border of the field at the obturator foramen, were randomly selected. A 5 half value layer cerrobent shield was positioned at the inferior border of the field. The dose to the testis was measured with and without the shield. Observations were made regarding the reflex cremaster contraction and phantom measurements were done at different distances from the perineum.

The mean radiation dose to the testis for patients receiving treatment with no shield was 7.4cGy (1.3) and it was 5.7cGy (-/+2.5) for patients with external shield, this difference was statistically significant by the paired t test p<0.0001. This accounted for a 22 % decrease in the dose received by the testis. The position of the testis with the contraction of the cremaster muscle and the dartos fascia after manipulation of the testis during diodes placement changed up to 3.5 cm (mean 1.5). Phantom measurements showed 37% increase in the dose with 2cm change in the position of the testis to the pelvic direction.

External shield at the inferior border of the pelvic field is a simple, easy reproducible, convenient shielding method. Clam-shell scrotal shield is not free of drawbacks, but still its benefits overweigh its harms and should be used with caution.