Prarthana Pasricha (Carleton University)
Shining light on microdosimetry: A novel system for micron-scale analysis of energy deposition
Understanding the interaction of ionizing radiation with tissue is crucial for improving cancer treatments. This includes accurately assessing the deposition of radiation energy and connecting to cellular-level responses. Ongoing studies on experimental techniques that combine Raman spectroscopy (RS) with radiochromic film (RCF) for high-spatial-resolution dosimetry are promising. Raman spectroscopy relies on the inelastic scattering of laser light caused by vibrations of chemical bonds within molecules and has been demonstrated to be highly effective for studying the radiation response of biological materials. On the other hand, computational methods, for example, Monte Carlo (MC) approaches are useful for modeling energy deposition in cellular targets.
In this study, we introduce an innovative system that integrates Raman Spectroscopy, Monte Carlo simulations and analysis techniques like Haralick Analysis, to precisely calculate and analyze energy deposition and response in irradiated radiochromic film, all at micron scale resolution. It offers both qualitative and quantitative insights into radiation energy deposition in cell-scale targets. Ongoing efforts focus on developing advanced machine learning techniques to directly correlate RS and MC results for enhanced analysis with potential of direct translation to cell systems.
Trevor Stocki (Health Canada)
“Coincidence Summing: Don’t be Afraid” & other gamma-ray spectrometry stories
Gamma ray spectrometry is an extremely sensitive methodology that counts gamma rays from individual radioactive atoms (radionuclides). This powerful technique is used to assess radioactivity after a nuclear accident, natural occurring radioactivity, or the contamination level in environmental samples, among other things. The efficiency of the gamma ray detector for a given radionuclide is a function of the energy of the gamma rays. Some radionuclides emit multiple gamma rays and if both of these gamma rays hit the detector at the same time, the energy deposited in the detector is the sum of the energies of the two gamma rays. This is known as coincidence summing and will affect the efficiency calibration. Coincidence summing has been extensively studied and continues to be a research topic for radioactive volume sources. The problem of coincidence summing for point sources has been solved. I did a literature review of coincidence summing and then used information relevant to characterizing a detector with point sources to implement an algorithm based on that information. In one paper the authors explained the fact that coincidence summing was used to do their efficiency calibration; i.e. they didn’t see coincidence summing as a problem, but as an advantage. An algorithm based on a literature review has been developed for coincidence summing corrections and used on measurement data. To date, the algorithm has been successfully tested on known results which don’t have coincidence summing issues as an initial validation that the algorithm works. It has also been successfully tested on spectra with known coincidence summing effects. Coincidence summing is an important parameter for calibrating and using gamma ray spectroscopy systems.