What is the wall thickness of the chamber used for beam output measurements in the KV region?

What is the wall thickness of the chamber used for beam output measurements in the KV region?

• A. 20 to 40 mg/cm²
• B. 40 to 60 mg/cm²
• C. 60 to 90 mg/cm²
• D. 90 to 120 mg/cm²

Answer: (C)

The wall thickness of the ionization chamber used for beam output measurements in the kilovolt (kV) region is typically in the range of 60 to 90 mg/cm². This thickness is important because it balances the need for adequate stopping power for the low-energy photons commonly used in kV radiotherapy while also minimizing the loss of primary radiation through the chamber walls. Thicker walls could lead to additional attenuation of the beam, which would adversely affect the accuracy of the dose measurements. Therefore, selecting a wall thickness within this range helps to ensure that the chamber can accurately measure the radiation output without significant interference from the chamber material itself.

The wall thickness of the ionization chamber used for beam output measurements in the kilovolt (kV) region is typically in the range of 60 to 90 mg/cm². This thickness is important because it balances the need for adequate stopping power for the low-energy photons commonly used in kV radiotherapy while also minimizing the loss of primary radiation through the chamber walls. Thicker walls could lead to additional attenuation of the beam, which would adversely affect the accuracy of the dose measurements. Therefore, selecting a wall thickness within this range helps to ensure that the chamber can accurately measure the radiation output without significant interference from the chamber material itself.