Fig. 1. The flow of intensity-modulated radiotherapy (a)^[11]and its steep dose gradient (b)^[12]

Fig. 2. Commonly used radiotherapy dosimeters: (a) ionization chamber matrix interpolation^[19]; (b) film dosimeters^[20]; (c) gel dosimeters^[21]

Fig. 3. Schematic diagram of the overall design of radiolytic color-changing inverse opal photonic crystal films: (a) schematic of photonic crystal dosimeters with different sensitivities based on three strategies: radiodegradable materials,sensitized radiodegradable materials by plasticization,and radiolytic cross-linking materials; (b) principle of formation of characteristic Bragg reflections of photonic crystals; (c) mechanism of characteristic peak shifts of photonic crystals; (d) radiation induced patterning and spatial resolution of photonic crystal materials^[33]

Fig. 4. Tuning the response performance of PEGDA photonic crystal dosimeters: (a),(b),(c) radiation response of PEG-plasticized PEGDA inverse opal photonic crystals,variation of color,spectra,and position of reflection peaks with absorbed dose; (d),(e) Response properties of inverse opal photonic crystals with different molecular weights and degrees of plasticization^[33](color online)

Fig. 5. Preparation and radiochromic properties of methacrylated gelatin inverse opal hydrogel films: (a) preparation of hydrogel inverse opal photonic crystal; (b),(c),(d) radiation response of hydrogel inverse opal photonic crystal: changes of color,spectra,and position of reflection peaks with increasing of absorbed dose; (e),(f) microscopic photos of irradiation patterned photonic crystals and reflectance spectra of different regions; (g),(h) microscopic photos of photonic crystals with irradiation induced pattern ^[33](color online)

Fig. 6. Response performance of a highly sensitive hydrogel photonic crystal radiation dosimeter on clinical radiotherapy device: (a),(b),(c) radiation response of high-sensitivity hydrogel inverse opal photonic crystals under radiotherapy X-rays: color,spectra,and reflection peak positions with absorbed dose; (d),(e),(f) radiation response of high-sensitivity hydrogel inverse opal photonic crystals under radiotherapy electrons: color,spectra,and reflection peak positions with absorbed dose; (g) photographs of high-sensitivity hydrogel inverse opal photonic crystals after zonal irradiation; (h),(i),(j) distribution of patterned irradiation fields obtained by commercial dosimeters^[34]; all scale bars in the figures are 3 cm (color online)

Fig. 7. 3D printed photonic crystal hydrogel dose-responsive materials and properties: (a) schematic diagram of 3D printed photonic crystals; (b),(c) photographs of the radiative response of 3D printed hydrogel photonic crystals; (d),(e) spectra of the 3D printed radiochromic hydrogel photonic crystals and the wavelength variation of the reflection peak^[34](color online)

Fig. 8. Preparation of advanced hydrogel materials by radiation induced penetrating grafting method:(a) preparation principle of radiation penetrating grafting method and demonstration of the properties of the prepared materials^[35];(b) preparation of high-precision hydrogel molding system

Fig. 9. Structure of interferometric radiation dosimeters with periodic stacked thin-film structures and their response: (a) structure of the dosimeter; (b),(c) response of a radiation cross-linked dosimeter; (d),(e) response of a radiolytic degradable dosimeter^[36]

Fig. 10. Structure and response of metal/microgel/metal interferometer dosimeters: (a) design of interferometer dosimeters; (b) response of S-S MGs dosimeters; (c) response of Se-Se/Te-Te MGs dosimeters^[37]