Addressing Limitations of a Spatially Sensitive Large-Area Ion Chamber for Real-Time Verification of Intensity Modulated Radiation Therapy
[Thesis]
Xun Lin
Islam, Mohammad K.; Heaton, Robert K.
University of Toronto (Canada)
2015
95
Committee members: Coolens, Catherine; Dolan, Alf M.; Jaffray, David A.
Place of publication: United States, Ann Arbor; ISBN=978-1-339-28229-9
M.H.Sc.
Biomedical Engineering
University of Toronto (Canada)
2015
Lack of light transparency and overall thickness are limitations of a previously described spatially sensitive large-area ionization chamber used for real-time verification of radiation therapy beam delivery. The first limitation was addressed with investigation of a commercially available light transparent conductive glass plates as replacements for aluminum plates in the construction of the chamber. Resulting chamber produced expected spatial sensitivity, allowed the light field to be transmitted with 35% attenuation in intensity, and caused deviation of field position due to refraction up to 0.4 mm. The second limitation was investigated with a novel interleaved comb patterned electrode pairs. The pattern was ablated on a light transparent conductive glass plate and utilized for construction of an experimental prototype ionization chamber that was 35% thinner, light transparent, and produced a spatial sensitivity comparable to the original design. However, further refinement in the design and manufacturing process will be necessary to make a practical comb patterned ionization chamber pair.
Biomedical engineering; Biophysics; Oncology
Biological sciences;Applied sciences;Health and environmental sciences;Imrt;Large area ionization chamber;Light transparency;Online treatment verification;Real-time quality assurance