What is ion chamber radiotherapy?

The ionization chamber is a radiation detector that is used to detect and measure charge from the number of ion pairs created within a gas caused by incident radiation. It consists of a gas-filled chamber with two electrodes; anode and cathode, in which a voltage is applied to maintain an electric field.

What is ion chamber radiotherapy?

The ionization chamber is a radiation detector that is used to detect and measure charge from the number of ion pairs created within a gas caused by incident radiation. It consists of a gas-filled chamber with two electrodes; anode and cathode, in which a voltage is applied to maintain an electric field. An ionization chamber consists of a gas-filled cavity surrounded by two electrodes of opposite polarity and an electrometer. The electric field established between the electrodes accelerates the ions produced by the radiation to be collected by the electrodes.

This charge is read by the electrometer and can be converted into absorbed dose. The studies focused on the statistical and physical performance of the ionization chamber dosimeter used in the radiotherapy department of the CHU-FEZ-Morocco oncology hospital. Since the sensitivity of the camera is proportional to the volume, the effect of leakage on the measured load is relatively greater for small cameras. This makes open-air ionization chambers the preferred reference dosimeter for Accredited Dosimetry Calibration Laboratories (ADCL), but their large size makes them unsuitable for clinical applications.

In medical physics and radiation therapy, ionization chambers are used to ensure that the dose delivered from a therapy unit or radiopharmaceutical is as intended. The gas amplification curve describes the behavior of an ionization chamber as a function of the applied voltage. Open-air ionization chambers are the defining instrument of the Roentgen unit and, as such, are fundamentally linked to the absorbed dose. Because these chambers are long, the flow of electrons through them may not be uniform (there may be no temporal uniformity in the volume of the chamber).

With reference to the attached ion pair collection graph, it can be seen that in the operating region of the ion chamber, the charge of a collected ion pair is effectively constant over an applied voltage range, since due to its relatively low electric field strength, the ion chamber has no multiplication. effect. There are two basic configurations; the integral unit with the camera and electronics in the same housing, and the two-piece instrument having a separate ion chamber probe attached to the electronics module by a flexible cable. The CC13 ionization chamber is designed for absolute and relative dosimetry of photon, electron and proton beams in radiation therapy.

A gas ionization chamber measures charge from the number of ion pairs created within a gas caused by incident radiation. Multi-cavity ionization chambers can measure the intensity of the radiation beam in several different regions, providing information on the symmetry and flatness of the beam. When the atoms or gas molecules between the electrodes are ionized by the incident ionizing radiation, ion pairs are created and the resulting positive ions are created and the dissociated electrons move to the electrodes of the opposite polarity under the influence of the electric field. The response of an ionization chamber depends to a large extent on the voltage applied between the outer electrode and the center electrode.

Tami Arunachalam
Tami Arunachalam

Amateur travel trailblazer. Hipster-friendly food enthusiast. Proud twitter geek. Passionate beer guru. Evil twitter geek. Lifelong coffee maven.

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