National Calibration and Measurement Capability (CMC) of Radiotherapy Ionization Chambers in Terms of Absorbed Dose to Water D_w in ~(60)Co Energy

摘要

According to the Mutual Recognition Agreement (MRA) of the International Committee of Weights and Measures (CIPM) the Secondary Standard Dosimetry Laboratory (SSDL) of the Instituto Nacional de Investigaciones Nucleares (ININ) is the Designated Institute (DI) by the Centro Nacional de Metrologia (CENAM) before the CIPM to establish and maintain the national standard for dosimetric quantities of ionizing radiation. In particular, the SSDL's main purpose is to provide assistance for quality assurance (QA) and calibration services in terms of absorbed dose to water (D_w) to radiotherapy centers in Mexico, that employ external ~(60)Co photon beams or high-energy x-rays for treatment of malignant neoplasia. Specifically, to achieve tumor control in the patient the absorbed dose should be given with an expanded uncertainty U(k = 2) ≤ 5%. Hence the SSDL-ININ has developed the D_w's Calibration and Measurement Capabilities (CMC) for the calibration of ionization chambers, by a coefficient calibration N_(Dw) with U (k = 2) ≤1%, based on the International Atomic Energy Agency Technical Report Series 398 international practice code.