Radionuclides emitting high-energy beta rays are frequently employed for therapeutic purposes in the field of medicine. However, it is widely recognized that such radionuclides have the potential to generate in vivo bremsstrahlung radiation. This research study focused on investigating the dose rate of bremsstrahlung radiation emanating from a radioactive source embedded in a patient. To accomplish this, we estimate the spectral energy distribution of the generated bremsstrahlung. By employing this spectral distribution, we present a novel method for estimating the bremsstrahlung dose rate kernel applicable to a given combination of source and material. This method considers photon buildup and attenuation, as well as the encapsulation of the radiation source. Furthermore, we provide formulas for both monoenergetic electrons and beta-transition electrons that account for radioactive decay.