HDR Planning

Abstract

In contrast to LDR techniques, HDR brachytherapy (BT) prostate techniques are less standardized, leading to a variety of planning techniques, dose prescriptions, and target volume concepts. The most common form of HDR BT for prostate is the use of HDR as a boost technique. In this case, the BT is delivered in combination with external beam in a dedicated, but not standardized, fractionation scheme (Kovács et al. 2005). HDR as monotherapy is also possible but is still subject of ongoing clinical research (Martin et al. 2004; Kovács et al. 2005). There are two common target volume concepts; the first involves using the prostate gland as a single CTV, with or without a margin, and the second uses two CTVs with CTV1 defined as the whole prostatic gland and CTV2 defined as the peripheral zone (Galalae et al. 2002; Aebersold et al. 2004). Prior to the start of treatment, maximum doses for organs at risk (urethra and rectum) must be defined. The GEC-ESTRO report recommends that urethral doses be kept below 10 Gy per fraction and rectal doses below 6 Gy per fraction (Kovács et al. 2005). Table 11.1 lists a variety of dose prescriptions and target volume definitions for HDR prostate boost techniques.