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Author Olguin, E. ♦ Flampouri, S. ♦ Lipnharski, I. ♦ Bolch, W.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION PROTECTION AND DOSIMETRY ♦ ANIMAL TISSUES ♦ CALIBRATION ♦ COMPUTERIZED SIMULATION ♦ DOSIMETRY ♦ FIBERGLASS ♦ LUNGS ♦ MONTE CARLO METHOD ♦ PHENOLS ♦ PROTON BEAMS ♦ RADIOTHERAPY ♦ SKELETON ♦ STOPPING POWER ♦ TISSUE-EQUIVALENT MATERIALS ♦ URETHANE
Abstract Purpose: To develop new proton tissue equivalent materials (PTEM), urethane and fiberglass based, for proton therapy calibration and dosimetry studies. Existing tissue equivalent plastics are applicable only for x-rays because they focus on matching mass attenuation coefficients. This study aims to create new plastics that match mass stopping powers for proton therapy applications instead. Methods: New PTEMs were constructed using urethane and fiberglass resin materials for soft, fat, bone, and lung tissue. The stoichiometric analysis method was first used to determine the elemental composition of each unknown constituent. New initial formulae were then developed for each of the 4 PTEMs using the new elemental compositions and various additives. Samples of each plastic were then created and exposed to a well defined proton beam at the UF Health Proton Therapy Institute (UFHPTI) to validate its mass stopping power. Results: The stoichiometric analysis method revealed the elemental composition of the 3 components used in creating the PTEMs. These urethane and fiberglass based resins were combined with additives such as calcium carbonate, aluminum hydroxide, and phenolic micro spheres to achieve the desired mass stopping powers and densities. Validation at the UFHPTI revealed adjustments had to be made to the formulae, but the plastics eventually had the desired properties after a few iterations. The mass stopping power, density, and Hounsfield Unit of each of the 4 PTEMs were within acceptable tolerances. Conclusion: Four proton tissue equivalent plastics were developed: soft, fat, bone, and lung tissue. These plastics match each of the corresponding tissue’s mass stopping power, density, and Hounsfield Unit, meaning they are truly tissue equivalent for proton therapy applications. They can now be used to calibrate proton therapy treatment planning systems, improve range uncertainties, validate proton therapy Monte Carlo simulations, and assess in-field and out-of-field organ doses.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-06-15
Publisher Place United States
Journal Medical Physics
Volume Number 43
Issue Number 6


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