Optimization approaches for treatment planning in two novel high-dose-rate (HDR) brachytherapy techniques, direction-modulation brachytherapy (DMBT) and energy-modulated brachytherapy (EMBT), are investigated for cervical cancer and prostate cancer. Brachytherapy is a form of radiation therapy where a radioactive source is placed inside the body to irradiate the tumour internally. Conventionally, only one source is used and it is unshielded, thus providing an isotropic dose distribution. DMBT makes use of a new shielded applicator that is capable of delivering highly directional radiation distributions. In EMBT, three HDR sources, 192Ir, 60Co, and 169Yb, are used in combination to provide variety in dose profiles. To investigate the benefit of these two new techniques over conventional brachytherapy, we use an inverse planning approach to generate the treatment plans. We model the treatment planning problem as a quadratic program and use an interior point constraint generation algorithm to generate the treatment plans.