TLD‐100 and radiochromic dye films are two types of the dosimeters most used in the medical physics area. Both are secondary detectors and operate in a different way and in different dose measurement ranges. The use of TLD‐100 is based on the thermoluminescent process, and the RDF in the optical density change when has been exposed to an irradiation field previously. In this work it is analyzed in a general way, the advantages and characteristics of these detectors and the reasons of the great increase in their use in the last decades.