Ion chamber for radiation measurement
An ion chamber has a chamber having an interior volume. There is a first electrode and a second electrode in the chamber and separated by a gap. A collector electrode is positioned between the first electrode and the second electrode. The collector electrode is shaped to occlude a portion of the first electrode from the second electrode.
1. A system comprising:
an ion chamber comprising:
a chamber having an interior volume;
at least one collector electrode configured to collect charge within the chamber; and
a material having a thickness sufficient to stop nearly all electrons from entering the chamber.
2. The system of claim 1 , wherein the material is an entrance window of the ion chamber.
3. The system of claim 1 , wherein the material is a filter or other material placed at or near an entrance of the ion chamber.
4. The system of claim 1 , wherein the material is an entrance window of the ion chamber combined with a filter or other material.
5. The system of claim 1 , wherein the material includes aluminum.
6. The system of claim 5 , wherein the aluminum has a wall thickness of approximately 2 mm.
7. The system of claim 5 , wherein the aluminum has a wall thickness of approximately 3 mm.
8. The system of claim 5 , wherein the aluminum has a wall thickness of approximately 4 mm.
9. The system of claim 5 , wherein the aluminum has a wall thickness of approximately 6 mm.
10. The system of claim 5 , wherein the aluminum has a wall thickness of approximately 8 mm.
11. The system of claim 1 , wherein the at least one collector electrode includes center electrodes.
12. The system of claim 11 , further comprising:
a ring electrode inside the chamber; and
a non-transitory, machine-readable medium storing instructions which, when executed by at least one programmable processor, cause the at least one programmable processor to perform operations comprising:
measuring current received at the center electrodes;
measuring current received at the ring electrode; and
calculating a beam energy of a radiation beam based at least on a ratio of the current received at the center electrodes and the current received at the ring electrode.