On the property of measurements with the PTW microLion chamber in continuous beams

Abstract

This is an accepted version of a paper published in Medical physics (Lancaster). This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the published paper: Andersson, J., Johansson, E., Tölli, H. (2012) "On the property of measurements with the PTW microLion chamber in continuous beam" Medical physics (Lancaster)

Modeling ion recombination in liquid ionization chambers — Improvement and analysis of the two‐dose‐rate method

“…. Values for the parameter ξ 2 between 1 · 10 −3 and 4 have been used in the comparison to display a wide range of corresponding general collection efficiencies that are experimentally realistic for LICs, as determined by the two‐dose‐rate method in the previous works on 120 kVp X‐rays and annihilation photons . Furthermore, the work by Johansson and Wickman has been used to define a liquid as the sensitive media through the parameter λ …”

“…Experimental data from Andersson and Tölli and Andersson et al has been used to investigate the implementation of the approximation derived in the present work in a two‐dose‐rate method for 120 kVp X‐rays and annihilation photons, respectively. The results were evaluated by taking the ratio of corrected LIC to reference chamber (NACP‐02) charge readings (LIC/NACP‐02 charge).…”

“…Experimental works have indicated that application of Greening's description of general recombination for liquids should be valid for general collection efficiencies over 90% . However, Andersson et al found different valid ranges of general collection efficiencies for annihilation photons (> 70%), as compared to the original investigation that involved 120 kVp X‐rays (> 90%) …”

Investigating ion recombination effects in a liquid-filled ionization chamber array used for IMRT QA measurements

“…5,6 However, there is a tradeoff-the liquid reduces ion mobility, leading to ion collection times that are approximately 100 times larger than air-filled chambers, which increases ion recombination effects. [7][8][9][10][11][12][13] Ion recombination effects have been studied in LICs and found to be proportional to the frequency and dose of the pulses delivered to the detector, among other parameters that are typically constant during a measurement. The dose and frequency of the pulses at each detector will vary during an IMRT delivery due to the changing multileaf collimator (MLC) aperture and changing machine dose rate (MU/min), respectively.…”

Detecting ionizing radiation with optical fibers down to biomedical doses

“…None of them is an ideal dosimeter as the use of each single device depends on the specific application and measurement conditions. 6,10,11 Optical fibers have recently emerged at the frontier of IRs monitoring. 12 The majority of existing optical fiber detectors are extrinsic sensors, where fibers mainly serve to transmit light from the sensor's head, whether it be a thermoluminescent solid, diode, or scintillating medium.…”