IntroductionThere is limited evidence to guide the preparation of patients for radiotherapy. This paper describes the protocol for an evaluation of a radiation therapist led education intervention delivered to patients with breast cancer in order to reduce psychological distress.MethodsA multiple-baseline study is being used. Usual care data is being collected prior to the start of the intervention at each of three sites. The intervention is delivered by radiation therapists consulting with patients prior to their treatment planning and on the first day of treatment. The intervention focuses on providing sensory and procedural information to patients and reducing pretreatment anxiety. Recruitment is occurring in three states in Australia. Eligible participants are patients who have been referred for radiotherapy to treat breast cancer. 200 patients will be recruited during a usual care phase and, thereafter, 200 patients in the intervention phase. Measures will be collected on four occasions—after meeting with their radiation oncologist, prior to treatment planning, on the first day of treatment and after treatment completion. The primary hypothesis is that patients who receive the radiotherapy preparatory intervention will report a significantly greater decrease in psychological distress from baseline to prior to radiotherapy treatment planning in comparison with the usual care group. Secondary outcome measures include concerns about radiotherapy, patient knowledge of radiotherapy, patient preparedness and quality of life. Patient health system usage and costs will also be measured. Multilevel mixed effects regression models will be applied to test for intervention effects.EthicsEthics approval has been gained from Curtin University and the three recruiting sites.DisseminationResults will be reported in international peer reviewed journals.Trial registration numberAustralian and New Zealand Clinical Trials Registration: ACTRN12611001000998.