Clinical workflow for reirradiation: national consensus recommendations on imaging, treatment planning, dose accumulation, and treatment delivery.

Background and purpose: Reirradiation is becoming more frequent in clinical practice. However, workflows and practices vary widely between clinics, as general guidelines are scarce or lacking in practical detail. This paper presents comprehensive national Danish consensus recommendations covering all steps of the reirradiation workflow. The aim is to standardise and improve reirradiation treatment quality and provide guidance for much-needed large-scale clinical trials.

Methods: An expert panel was formed comprising physicians, clinical physicists, and clinical researchers from all Danish radiotherapy centres. An in-person 2-day workshop was followed by multiple online meetings. Recommendations were based on expert consensus, supported by review of existing literature, and were reviewed by all Danish Multidisciplinary Cancer Groups before publication.

Results: Reirradiation cases should be designated clearly as such at each workflow step. Review of patient cases at multidisciplinary reirradiation conferences is encouraged. Immobilisation, positioning, and motion management should resemble that of previous treatment(s) as closely as possible. Information on previous dose should be used in planning and evaluation. The degree of complexity (e.g. summation of dose maxima, rigid/deformable image registration, 3D dose accumulation) should reflect the clinical situation as well as the extent/quality of available information. Dose should always be converted to an equieffective dose before summation. Daily image-guidance and regular evaluation of delivered dose are recommended. We provide guidance on quality assurance of dose mapping and guidelines for clinical reirradiation trials.

Interpretation: We present national consensus guidelines for site-independent reirradiation treatment workflows. The guidelines have been approved by the site-specific Danish Multidisciplinary Cancer Groups.