[en] The aim of this paper is to investigate an accurate and convenient quality assurance programme that should be included in the dosimetry system of the radiotherapy level radiation. We designed a mailed solid phantom and used TLD-100 chips and a Rexon UL320 reader for the purpose of dosimetry quality assurance in Taiwanese radiotherapy centers. After being assembled, the solid polystyrene phantom weighted only 375 g which was suitable for mailing. The Monte Carlo BEAMnrc code was applied in calculations of the dose conversion factor of water and polystyrene phantom: the dose conversion factor measurements were obtained by switching the TLDs at the same calibration depth of water and the solid phantom to measure the absorbed dose and verify the accuracy of the theoretical calculation results. The experimental results showed that the dose conversion factors from TLD measurements and the calculation values from the BEAMnrc were in good agreement with a difference within 0.5%. Ten radiotherapy centers were instructed to deliver to the TLDs on central beam axis absorbed dose of 2 Gy. The measured doses were compared with the planned ones. A total of 21 beams were checked. The dose verification differences under reference conditions for ⁶⁰Co, high energy X-rays of 6, 10 and 15 MV were truly within 4% and that proved the feasibility of applying the method suggested in this work in radiotherapy dose verification