Brachytherapy (BRT) is defined as treatment from a short distance. The word is derived from the word
"brachy" that means "short" in Greek. Treatment in BRT is performed by placing the radioactive source in
or near the tumor tissue. According to the report 38 of the International Commission on Radiation Units
and Measurements (ICRU 38), BRT is divided into three types according to the activity of the radioactive
source. Low-dose rate (LDR) implants deliver dose at the rate of 0.4?2 Gy/h, requiring treatment times of
24?144 h. LDR BRT has extensive experience with well-known efficacy and side effects. Medium-dose rate
(MDR) BRT, defined as the 2?12 Gy/h range, is rarely used. High-dose rate (HDR) BRT uses dose rates in
excess of 0.2 Gy/min (12 Gy/h). Although not defined in ICRU 38, there is also a very-low dose (ultra LDR:
ultra-low dose rate (ULDR)) BRT of 0.01?0.3 Gy/h. Pulse dose rate (PDR) BRT is a new BRT concept that
is also not defined in ICRU 38. PDR BRT combines physical advantages of HDR BRT technology with the
radiobiological advantages of LDR BRT. Each dose rate in the clinic has its advantages and disadvantages. It
is difficult to compare the efficacy of dose rates in the clinic because of the lack of prospective randomized
studies comparing the defined dose rates with each other. In this review, we aimed to explain the advantages,
disadvantages, and common clinical sites of use of different dose rates.
Keywords: Brachytherapy; high-dose rate; low-dose rate; medium-dose rate; pulse dose rate; ultra-low dose rate
