The effect of contrast agent on dose distribution in treatment planning radiotherapy: A systematic review

One method of increasing the quality of CT images is the use of contrast agents. The evidence underscores the clinical importance of using contrast-enhanced imaging in the treatment planning process and highlights the potential to improve patient care and treatment effectiveness. The purpose of this study is to evaluate the quantitative changes caused by contrast agents used in CT simulator images for photon dosimetry in radiotherapy treatment planning.

The selected databases were Web of Science, PubMed, Scopus, Embase, and Google Scholar. The search string was applied in the title, abstract, and keywords fields across the three international databases. The search terms included: contrast agent, dose distribution, dose difference, treatment planning system, treatment planning, radiotherapy, and Iodine contrast. The articles search was conducted between July and August 2024. The identified articles were evaluated for methodological quality using the Joanna Briggs Checklist.

A total of 399 records, after removing duplicate records (n=153), studies were screened by title and abstract to assess eligibility. After removing unrelated studies, 25 articles were included. A systematic review study showed that the difference in dose between the use of contrast agents and without contrast agents was 2% or less than 2%. Only three studies with 36 patients showed the dose differences were more than 2%.

This systematic review concluded that the use of contrast agents in radiotherapy at different sites and with different techniques does not significantly affect the extent of dose distribution changes, and this small difference is clinically acceptable.