Fractionated CyberKnifeTM stereotactic radiotherapy for patients with prostate cancer: presentation of the method

Abstract

A significant technological development of radiotherapy in the last several years has enabled the implementation in
daily practice of highly specialized procedures for accurate imaging and precise irradiation for patients with prostate
cancer.
Due to the numerous reports on the low value of the alpha/beta ratio for prostate cancers, using such technology
gives an opportunity to implement hypofractionated radiotherapy safely.
This article presents the first Polish implementation of CyberKnifeTM based stereotactic radiotherapy for prostate
cancer patients.

Eligibility for treatment includes low risk prostate cancer patients with good performance status and biopsy confirmed prostate cancer. Preparing the patient for IGRT procedures includes transrectal implantation of golden markers and patient immobilization using a vacuum pillow.
Treatment planning was based on the fusion of computed tomography and magnetic resonance imaging. Verification of prostate position was performed by localization of implanted markers using two orthogonal kilovoltage beams and detectors.
The dose of 7.25 Gy per fraction to a total dose of 36.25 Gy was used to irradiate the prostate tumor with a margin. The organs at risk are rectum, bladder, femoral heads and the urethra.
A comparative analysis of the doses used in conventional and hypofractionated radiation therapy after estimation as the normalized total dose (NTD) and the biologically effective dose (BED) was made.
Estimation of the risk of adverse effects in healthy tissues, both for acute and late reactions, justifies using stereotactic fractionated radiotherapy for patients suffering from prostate cancer.
Reduction of total treatment time is justified from an economic as well as an ethical point of view.