Characterization of the PTW-34089 type 147 mm diameter large-area ionization chamber for use in light-ion beams.

Characterization of the PTW-34089 type 147 mm diameter large-area ionization chamber for use in light-ion beams.
Phys Med Biol. 2020 Jun 01;:
Authors: Kuess P, Haupt S, Osorio J, Grevillot L, Fuchs H, Georg D, Palmans H
Abstract
A newly-designed large-area plane-parallel ionization chamber (of type PTW 34089), denoted BPC150, with a nominal active volume diameter of 147 mm is characterized in this study. Such chambers exhibit benefits compared to smaller chambers in the field of scanned light-ion beam dosimetry because they capture a larger fraction of the laterally-spread beam fragments and ease positioning with respect to small fields. The chamber was characterized in60Co, 200 kV X-ray, proton and carbon ion beams. The chamber-specific beam-quality correction factor kQ,Q0was determined. To investigate the homogeneity of the chamber's response, a radial response map was acquired. An edge correction was applied when the proton beam only partly impinged on the chamber's active surface. The measured response map showed that the response in the chamber's center is 3% lower than the average response over the total active area. Furthermore, percentage depth dose (PDD) curves in carbon ions were acquired and compared to those obtained with smaller-diameter chambers (i.e. 81.6 mm and 39.6 mm) as well as with results from Monte Carlo simulations. The measured absorbed dose to water cross calibration coefficients resulted in a kQ,Q0of 0.981±...

Source: Physics in Medicine and Biology - May 31, 2020 Category: Physics Authors: Kuess P, Haupt S, Osorio J, Grevillot L, Fuchs H, Georg D, Palmans H Tags: Phys Med Biol Source Type: research