Volunteers participating in medical research must be adequately protected. A volunteer can be a person undergoing treatment for an illness (a patient) or a healthy person. The radiological imaging and therapy procedures used could be routine or project-specific with different purposes. This contribution aims to explore the features and conditions of this planned exposure situation and to address some challenges. The result of a national study is presented. The main aspects covered in this presentation are justification, optimisation of radiation protection and the use of dose constraints. The guidelines in ICRP Publication 62 were reflected upon.