Clinical Implementation of Simulation-Free Palliative Radiation Therapy: Consensus Recommendations From a Modified Delphi Study

Abstract

Purpose: Simulation-free radiation therapy (sim-free RT) uses diagnostic computed tomography scans in place of dedicated computed tomography simulations for treatment planning, potentially expediting palliative radiation therapy (PRT) while optimizing resource utilization. Broader adoption has been limited by the absence of standardized implementation guidance. This study aimed to establish expert consensus on key clinical, technical, and educational considerations for sim-free RT in PRT practice.

Methods and materials: A modified Delphi process was conducted with international experts in sim-free RT, including radiation oncologists (n = 7), medical physicists (n = 2), a radiation therapist, and a PhD candidate specializing in PRT. The process included an open-ended first round followed by 3 Likert-scale survey rounds across 12 domains. Consensus was defined as ≥75% agreement; ≥90% agreement indicated strong support. "Trend toward agreement" was defined as 67% to 74%.

Results: Nine respondents, representing 11 individual experts from 8 institutions in 5 countries, completed all study rounds. Experts from the same institution responding as a group were considered as 1 participant. Consensus was achieved for 95% of statements. Strong support was observed for sim-free RT in palliative-intent treatments at low-risk sites (eg, thoracic/lumbar spine, pelvis) using conventional dose-fractionation. Recommended prerequisites included recent high-quality diagnostic scans (≤3 mm slice thickness, 100-140 kVp), robust image quality assurance, and multidisciplinary oversight. Areas of limited agreement included the use of older scans, application to cervical spine targets, and integration with intensity modulated radiotherapy/volumetric modulated arc therapy planning.

Conclusions: This Delphi study provides expert-driven recommendations to support safe implementation of sim-free RT in palliative practice. Findings highlight suitable indications, workflow safeguards, and training needs while underscoring the need for further dosimetric validation and broader evaluation across diverse practice settings.

Figure 1

Examples of statements, responses, and revised statements presented to participants. Abbreviation: BED = biological effective dose; CT = computed tomography; PTV = planning target volume; SABR = stereotactic ablative body radiotherapy.