Citation: Mohyedin, M.Z.; Zin, H.M.; Adenan, M.Z.; Abdul Rahman, A.T. A Review of PRESAGE Radiochromic Polymer and the Compositions for Application in Radiotherapy Dosimetry. Polymers 2022, 14, 2887. https://doi.org/10.3390/ polym14142887 Academic Editor: Mohamed F. Attia Received: 6 June 2022 Accepted: 6 July 2022 Published: 16 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). polymers Review A Review of PRESAGE Radiochromic Polymer and the Compositions for Application in Radiotherapy Dosimetry Muhammad Zamir Mohyedin 1,2 , Hafiz Mohd Zin 3 , Mohd Zulfadli Adenan 4 and Ahmad Taufek Abdul Rahman 1,2, * 1 School of Physics and Material Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia; zamirmohyedin@gmail.com 2 Centre of Astrophysics & Applied Radiation, Institute of Science, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia 3 Advanced Medical & Dental Institute, Universiti Sains Malaysia, Bertam, Kepala Batas 13700, Penang, Malaysia; hafiz.zin@usm.my 4 Centre of Medical Imaging, Faculty of Health Sciences, Universiti Teknologi MARA, Cawangan Selangor Campus of Puncak Alam, Puncak Alam 42300, Selangor, Malaysia; mohdzulfadli@uitm.edu.my * Correspondence: ahmadtaufek@uitm.edu.my Abstract: Recent advances in radiotherapy technology and techniques have allowed a highly con- formal radiation to be delivered to the tumour target inside the body for cancer treatment. A three-dimensional (3D) dosimetry system is required to verify the accuracy of the complex treatment delivery. A 3D dosimeter based on the radiochromic response of a polymer towards ionising radiation has been introduced as the PRESAGE dosimeter. The polyurethane dosimeter matrix is combined with a leuco-dye and a free radical initiator, whose colour changes in proportion to the radiation dose. In the previous decade, PRESAGE gained improvement and enhancement as a 3D dosimeter. Notably, PRESAGE overcomes the limitations of its predecessors, the Fricke gel and the polymer gel dosimeters, which are challenging to fabricate and read out, sensitive to oxygen, and sensitive to diffusion. This article aims to review the characteristics of the radiochromic dosimeter and its clinical applications. The formulation of PRESAGE shows a delicate balance between the number of radical initiators, metal compounds, and catalysts to achieve stability, optimal sensitivity, and water equivalency. The applications of PRESAGE in advanced radiotherapy treatment verifications are also discussed. Keywords: radiation dosimeter; three-dimensional dosimetry; polymer dosimeter; PRESAGE; radiotherapy 1. Introduction Cancer is one of the critical health issues worldwide [1]. Radiotherapy remains an important curative technique in cancer treatment. Approximately half of all cancer patients obtained radiotherapy as a part of their treatment regime [2]. The treatment may also be combined with other treatment modalities, which include chemotherapy or surgery [3–5]. Radiotherapy involves the delivery of a radiation dose to the tumour while limiting the dose to the surrounding healthy tissues during treatment. Typically, the radiation dose is delivered externally from a linear accelerator (linac) or internally in certain types of cancers, using radioactive sources. Figure 1 shows a schematic diagram of a linac that produces a highly focused ionising radiation in the patient. The ionising radiation is a high-energy X-ray produced by the X-ray targets, as shown in Figure 1. A wave guide is used to accelerate electrons in a part of the accelerator to allow these electrons to collide with the heavy metal X-ray target to produce the X-rays. These high-energy X-rays are shaped by a multileaf collimator system that is incorporated into the head of the machine to conform to the shape of the patient’s tumour. The beam can be Polymers 2022, 14, 2887. https://doi.org/10.3390/polym14142887 https://www.mdpi.com/journal/polymers