TD09-PHOTON AND ELECTRON BEAM DOSIMETRY

2A01-PHOTON AND ELECTRON BEAM DOSIMETRY

Faiz M. Khan, Ph.D.

The theory of measurement and calculation of absorbed dose using ion chamber will be discussed.  By considering ionization chamber as a Bragg-Gray cavity, relationships are derived between the ionization charge measured and the absorbed dose in the medium. The formalism, which is based on the AAPM TG-21 protocol, involves cavity-air calibration factor, restricted stopping power ratios of medium to air, and various chamber perturbation factors.  The TG-21 protocol will be compared with the IAEA TRS-277 protocol.

TD09 - 光子和电子束剂量学

Faiz M. Khan, Ph.D.

阐述用电离室测量和计算吸收剂量的理论。通过将电离室作为一个Bragg-Gray空腔，建立测量到的电离电荷与介质中吸收剂量的关系，计算公式（根据AAPM TG-21规程）包括空气腔校准因子、介质与空气的限制性阻止本领之比、及各种电离室扰动因子。将TG-21规程与IAEA TRS-277规程进行比较。