The use of a leg holder immobilisation device in 3D-conformal radiation therapy of prostate cancer

Background and purpose: To evaluate the impact of a leg holder immobilisation device on patient positioning accuracy in the treatment of prostate cancer.

Material and methods: Twenty patients of similar age and stage of disease treated with curative external beam radiotherapy for prostate cancer were included prospectively. Ten patients were sequentially allocated to one of the two groups, and treated either with or without a leg holder. Treatment set-up alignment accuracy was assessed with an electronic portal imaging device (EPID).

Results: Set-up accuracy was 0.3, 0.3 and 0.2 cm for patients with a leg holder, and 0.3, 0.4 and 0.2 cm for patients without a leg holder in the cranio-caudal, anterior-posterior and in the lateral positions, respectively. The difference is not significant. The repositioning accuracy of combined (sagittal and lateral) in-plane rotations on the other hand, was significantly improved with a leg holder device (P = 0.04).

Conclusions: Set-up accuracy can be improved using a leg holder immobilisation device in terms of rotational movement accuracy, thus making on-line corrections more accurate using EPID in the treatment of prostate cancer.