Clinical perspectives on dosimetry in molecular radiotherapy

• Published in: Physica medica 2023-10, Vol.114, p.103154-103154, Article 103154
• Main Authors: Davis, LauraMay, Elmaraghi, Caroline, Buscombe, John R., Gaze, Mark N.
• Format: Article
• Language: English
• Subjects: Administered activity; Humans; Individualised treatment; Molecular radiotherapy; Neoplasms - radiotherapy; Personalised care; Radiation absorbed dose; Radiation Dosage; Radiometry - methods; Radiopharmaceuticals - therapeutic use; Radiotherapy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Tumour dosimetry
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2023.103154

•Molecular radiotherapy has developed empirically over decades.•Prescription by administered activity is most often used.•This may result in a variable radiation absorbed dose to tumours.•There is a risk of undertreatment or possibly toxicity.•Routine use of tumour dosimetry may improve outcomes. Molecular radiotherapy is the use of systemically administered unsealed radioactive sources to treat cancer. Theragnostics is the term used to describe paired radiopharmaceuticals localising to a specific target, one optimised for imaging, the other for therapy. For many decades, molecular radiotherapy has developed empirically. Standard administered activity schedules have been used without the prior estimation of the resulting tumour radiation absorbed dose by theragnostic imaging, or its subsequent measurement by serial scanning. This pragmatic approach has benefited many patients, however others who should have benefited have failed to do so as the radiation absorbed dose in the tumour was suboptimal. The accurate prediction and measurement of tumour and organ at risk radiation absorbed doses allows treatment to be personalised, and offers the prospect of improved clinical outcomes. To deliver this for all molecular radiotherapy patients would require not only a significant financial investment in equipment and skilled personnel, but also a change in attitude of those who believe that simple – or simplistic – schedules are easier to deliver, and that accurate dosimetry is too much trouble. Further clinical studies are required to demonstrate beyond doubt that the advantages of individualised treatment planning outweigh the inconvenience, and that the expense is justified by enhanced results.