What is the recommended dosimeter for calibrating brachytherapy sources in terms of AKS?

The well-type ionization chamber is the recommended dosimeter for calibrating brachytherapy sources in terms of air kerma strength (AKS). This specialized type of ionization chamber is specifically designed to measure the output of low-energy photon radiation emitted from brachytherapy sources, which is crucial when establishing the dosimetric characteristics of these sources.

A well-type ionization chamber operates by housing the brachytherapy source within a cylindrical well that allows for uniform measurement of radiation exposure. Its design enables effective collection of ionization events that occur within the chamber when exposed to radiation, thereby providing accurate readings of the source's air kerma strength. This capability is particularly important in brachytherapy, where precise dosing is crucial for effective treatment planning and delivery.

In contrast, while photomultiplier tubes, thermoluminescent dosimeters, and liquid scintillation counters have their specific applications, they are not ideally suited for precisely calibrating brachytherapy sources in terms of AKS. Photomultiplier tubes are often used in situations involving scintillation detectors and may not provide direct measurements of air kerma strength. Thermoluminescent dosimeters are useful for personal dosimetry and high-energy photon measurements but lack the specificity for brachytherapy