Evaluations of two solid water parallel-plate chambers in high-energy photon and electron beams.

Using high-energy photon and electron beams, the response of two solid water parallel-plate chambers is evaluated against a PTW (Physicallsch-Technische Werkstatten) Farmer-type chamber. These two chambers are (1) a Memorial "Holt" chamber which was further modified by this author to take advantage of electrically conductive solid water, and (2) a thin window parallel-plate chamber designed by Attix. The evaluations are made for (1) stability and reproducibility, (2) polarity effect, (3) ion recombination correction, (4) field size dependence on output, (5) dose rate dependence on output, and (6) absorbed dose comparison in high-energy photon and electron beams using the American Association of Physicists in Medicine Task Group 21 (TG21) protocol.