Doctors mark the skin or mucous membranes to provide long-lasting visual cues for use during treatment. This technique is used in radiotherapy, for example, to frame the body part to irradiate by calibrating the irradiator’s collimation window. These markings can be different colours (skin, scalp, etc.). Endoscopic marking allows the tumour boundaries to be defined during exeresis surgery (specifically in the colon). The marking of tumour boundaries is practiced on the integument (breast surgery) or as an anatomical marking (the vascular pedicle of skin flaps in reconstructive surgery).