3D chemical dosimetry of radiotherapy is an interdisciplinary research related to medical physics, polymer and radiation chemistry, photochemistry, organic chemistry, computer science, oncology, materials engineering, and automation technology. It consists of a 3D high resolution tissue equivalent dosimeter, high resolution 3D reading, and software packages for fast processing of 3D measurement data. Research on 3D radiotherapy chemical dosimetry has been going on for almost forty years, starting with the first proposal of a 3D dosimeter -Fricke dosimetric solution in a physical gel matrix with magnetic resonance imaging (MRI) reading to record the spatial dose distribution. [1] Further research concerned both Fricke-gel dosimeters and other systems, such as polymer gel dosimeters, radiochromic gel and plastic dosimeters, and flexible dosimeters. Many dosimetric compositions have been proposed. As a general rule, each new 3D dosimeter has a specific acronym, usually derived from its components. Examples of 3D polymer gel dosimeters are as follows (the acronyms are associated with example references): BANG, [16] PAG, [17] PAGAT, [18] nMAG, nPAG, [19] MAGIC, [17,20] MAGIC-f, [21] NIPAM, [22,23] VIPAR, [24] VIP (VIPAR nd ), [25] VIC, [26] VIC-T, [26] VIP3-Pluronic F-127, [27,28] PAGAT2-Pluronic F-127, [29] PAB-IG nx , [14,30,31] NHMAGAT, [32] MAGADIT, [33] NMPAGAT. [34] Examples of 3D radiochromic dosimeters are as follows: PVA-GTA-XO-Fricke, [35,36] PVA-GTA-MTB-Fricke, [37] Fricke-XOgelatine, [38] Fricke-XO-Pluronic F-127, [10,13,39] TTC-Pluronic F-127, [40] NBT-Pluronic F-127, [41,42] KI-PVA, [43] KI-Pluronic F-127, [12] LCV-gelatine; [44] and 3D plastic radiochromic dosimeter: PRESAGE. [3,45,46] 3D flexible dosimeters have also been proposed: LMG-silicone, [47,48] FlexyDos3D, [49] as well as 3D lung-mimicking dosimeters: PAGAT-2-Pluronic F-127 foam, [11] foam based on methacrylic acid-gelatine infused with sodium dodecyl sulphate surfactant, [50] and methacrylic acid-gelatine gel with expanded polystyrene spheres. [51] It should be mentioned that alternative 3D reading techniques to MRI were also investigated, including computed tomography (CT), [22,23,52] ultrasonography, [53][54][55] and optical computed tomography (optical CT). [56,57] It has been shown that 3D dosimetry data This work reports on a new type of combined radiochromic ionizing radiation dosimeter for radiotherapy. The LCV-Pluronic F-127 serves for this purpose, which is a leuco crystal violet embedded in a physical hydrogel matrix of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127) with additives. This dosimeter responds to ionizing radiation by developing a blue color with an intensity related to the radiation dose. The LCV-Pluronic F-127 dosimeter is improved for lower temperature stability by adding sodium chloride (NaCl). Subsequently, a method for manufacturing the LCV-Pluronic F-127 lung mimicking dosimeter is proposed. Next, the LCV-Pluronic F-127 3D composite dosimeter is elaborated, which cont...