High brachytherapy is

According to ICRU repo 38, treatment dose rates fall into three categories * Low Dose Rate (LDR) brachytherapy ranges between 0.4 and 2 Gy/h. However, in routine clinical practice, LDR brachytherapy is usually delivered at dose rates between 0.3 and 1 Gy/h. This is compatible with conventional manual or automatic afterloading techniques. * Medium Dose Rate (MDR) brachytherapy ranges between 2 Gy/h and 12 Gy/h. MDR can also be delivered by manual or automatic afterloading, although the latter is far more frequent. * High Dose Rate (HDR) brachytherapy delivers the dose at 12 Gy/h or more, and only automatic afterloading can be used because of the high source activity.(Ref: Radiobiology of Brachytherapy and the Dose-Rate Effect by JJ Mazeron et al, 95)