Low-dose-rate brachytherapy (LDR) (LDR)

Low-dose-rate (LDR) brachytherapy is a form of internal radiation therapy where radioactive sources, often called "seeds," are placed directly into or near a tumor to deliver a continuous, low dose of radiation over several days or weeks (National Cancer Institute, 2023). Unlike external beam radiation, LDR brachytherapy allows for a highly localized dose of radiation, minimizing exposure to surrounding healthy tissues by utilizing the inverse square law of radiation physics (StatPearls, 2023). It is most commonly used in the treatment of localized prostate cancer, but is also applied in gynecological, head and neck, and breast cancers (American Brachytherapy Society, 2021). The biological effect is mediated through ionizing radiation, which induces double-strand DNA breaks and generates reactive oxygen species, leading to cell cycle arrest and apoptosis in rapidly dividing cancer cells (RadiologyInfo.org, 2022). While highly effective for local tumor control, safety concerns include potential damage to adjacent organs, such as the bladder or rectum, and the logistical requirements of handling radioactive materials (PubMed, 2020). From a clinical perspective, LDR brachytherapy is often preferred for its convenience, as it can be performed as a single-day procedure with a rapid return to normal activities (StatPearls, 2023). Recent research also explores its role in inducing immunogenic cell death, potentially synergizing with checkpoint inhibitors to treat metastatic disease (PubMed, 2020).

Other names

LDR-BTInterstitial brachytherapySeed implantationInternal radiation therapyPermanent seed brachytherapy

Delivery of continuous ionizing radiation from encapsulated radioactive sources placed within the tumor, leading to direct DNA ionization and indirect damage via water radiolysis, ultimately causing mitotic catastrophe and cell death (StatPearls, 2023).