Multicentre treatment planning inter-comparison in a national context: The liver stereotactic ablative radiotherapy case

Abstract

Purpose: To compare five liver metastasis stereotactic ablative radiotherapy (SABR) plans optimised in fourteen centres with 3D-Conformal-RT, IMRT, VMAT, CyberKnife and Tomotherapy and identify possible dosimetric differences.

Methods: Dose prescription was 75 Gy in 3 fractions, normalised at 67%-95% isodose.

Results: Excluding few cases, all institutions achieved the planning objectives. Differences up to 40% and 25% in mean dose to liver and PTV were found. No significant correlations between technological factors and DVH for target and OARs were observed; the optimisation strategies selected by the planners played a key role in the planning procedure.

Conclusions: The human factor and the constraints imposed to the target volume have a greater dosimetric impact than treatment planning and radiation delivery technology in stereotactic treatment of liver metastases. Significant differences found both in terms of dosimetric target coverage and OAR sparing should be taken into consideration before starting a multi-institutional SARB clinical trial.

Keywords: Dosimetry; Liver; Multicentric clinical trial; Stereotactic ablative radiotherapy (SABR); Stereotactic body radiation therapy (SBRT).