The present disclosure provides systems and methods for verifying radiation source delivery in brachytherapy by allowing for the radiation source location and dwell time to be determined via real-time measurement. In an embodiment, a radiation detector may be disposed proximate to a radiotherapy target. The radiation detector is configured to provide real-time information indicative of ionizing radiation emitted by a radiation source. A controller may perform operations including receiving, from the radiation detector, real-time information indicative of at least one of: a particle flux rate, an energy fluence, or an absorbed dose of ionizing radiation emitted from the radiation source. The operations may also include determining, based on the received information, at least one of: a location of the radiation source or a dwell time of the radiation source.