International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 2022, 11, 12-21 https://www.scirp.org/journal/ijmpcero ISSN Online: 2168-5444 ISSN Print: 2168-5436 DOI: 10.4236/ijmpcero.2022.111002 Jan. 24, 2022 12 Int. J. Medical Physics, Clinical Engineering and Radiation Oncology Dosimetric Effects of Thermoplastic Immobilizing Devices on Surface Dose Olivia Adu-Poku 1,2* , Eric Kotei Addison 1,2 , Cyril Schandorf 3 , Francis Hasford 3 , Stephen Inkoom 3,4 , Joseph Adom 1,2 , Akosah Kingsley 2 , Eunice Arthur 2 , Linus Owusu-Agyapong 2 1 Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana 2 Department of Medical Physics, Komfo Anokye Teaching Hospital, Oncology Directorate, Kumasi, Ghana 3 Department of Medical Physics, Graduate School of Nuclear and Allied Sciences, University of Ghana, Accra, Ghana 4 Radiation Protection Institute, Ghana Atomic Energy Commission, Accra, Ghana Abstract Thermoplastic immobilizing masks have dosimetric effects on the patient’s skin dose. The thermoplastic percentage depth dose (PDD), equivalent thick- ness of water for the masks and surface doses were determined. The surface dose factors due to the thermoplastic mask was found to be 1.7949, 1.9456, 2.0563, 2.1967, 2.3827, 2.5459 and 2.6565 for field sizes of 5 × 5, 8 × 8, 10 × 10, 12 × 12, 15 × 15, 18 × 18 and 20 × 20 cm 2 respectively which shifted the per- centage depth dose curve to lower values. The physical thermoplastic thickness was measured to be between 2.30 and 1.80 mm, and the equivalent thicknesses of water, d e , were determined to be between 1.2 and 1.00 mm. This meant that, as the mask thickness decreased, its water equivalent thickness also decreased. The presence of the mask material increased the skin dose to a factor of 1%. The thermoplastic mask factor was also found to be 0.99. Keywords Thermoplastic Mask, Percentage Depth Dose, Equivalent Thickness of Water, Skin Dose 1. Introduction Thermoplastics are organic materials which are ductile in nature. They can be formed after softening and retain their final shape when cooled. The chemistry of thermoplastics is comparable to that of rubber, while the strength is similar to aluminium. They are light in weight with densities ranging from 0.9 to 2 g/cm 3 . These properties, along with their low cost make them appropriate for several How to cite this paper: Adu-Poku, O., Addi- son, E.K., Schandorf, C., Hasford, F., Inkoom, S., Adom, J., Kingsley, A., Arthur, E. and O- wusu-Agyapong, L. (2022) Dosimetric Effects of Thermoplastic Immobilizing Devices on Surface Dose. International Journal of Medi- cal Physics, Clinical Engineering and Radia- tion Oncology, 11, 12-21. https://doi.org/10.4236/ijmpcero.2022.111002 Received: June 1, 2020 Accepted: January 21, 2022 Published: January 24, 2022 Copyright © 2022 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access