"红外线照射" can be translated into English as "infrared radiation" or, more specifically when referring to the act of applying it, "infrared irradiation" or "exposure to infrared radiation".
Infrared radiation is the general term for the electromagnetic radiation with wavelengths longer than those of visible light but shorter than those of radio waves.
Infrared irradiation emphasizes the action of applying infrared radiation to a specific area or object.
Exposure to infrared radiation describes the situation where something (like a person or a material) is subjected to infrared radiation.
In medical or therapeutic contexts, you might also hear terms like "infrared therapy" or "infrared treatment", which specifically refer to the use of infrared radiation for therapeutic purposes.