1148 - General and Organ Specific Consensus Recommendations for Stereotactic Body Radiotherapy Dose Prescription according to ICRU Report 91 from Working Groups on Stereotactic Radiotherapy

T. B. Brunner¹, J. Boda-Heggemann², D. Buergy², S. Corradini³, U. K. Dieckmann⁴, S. Gerum⁵, E. Gkika⁶, J. Hoerner-Rieber⁷, S. Kirste⁸, R. Klement⁹, C. Moustakis¹⁰, M. Niyazi¹¹, A. Ruehle¹⁰, S. Tanadini-Lang¹², P. Winkler¹³, B. Zurl¹⁴, and O. Blanck¹⁵; ¹Medical University of Graz, Dept. of Radiation Oncology, Graz, Austria, ²Department of Radiation Oncology, University Medicine Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany, ³Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany, ⁴Department of Radiation Oncology, Medical University of Graz, Graz, Austria, ⁵Department of Radiotherapy and Radiation Oncology, Paracelsus Medical University, Landeskrankenhaus, Salzburg, Austria, ⁶Department of Radiation Oncology, University Hospital Bonn, Bonn, Germany, ⁷Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany, ⁸German Cancer Consortium (DKTK), Partner Site Freiburg, Heidelberg, Germany, ⁹Department of Radiotherapy and Radiation Oncology, Leopoldina Hospital Schweinfurt, Schweinfurt, Germany, ¹⁰Department of Radiation Oncology, University Hospital Leipzig, Leipzig, Germany, ¹¹Department of Radiation Oncology, University Hospital Tübingen, University of Tübingen, Tübingen, Germany, ¹²Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland, ¹³Medical University of Graz, Graz, Austria, ¹⁴Department of Therapeutic Radiology and Oncology, Comprehensive Cancer Center, Medical University of Gra, Graz, Austria, ¹⁵Department of Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel, Germany

Purpose/Objective(s): To develop expert recommendations for multiparametric dose prescriptions of SBRT according to ICRU report 91 to harmonize current SBRT practice and clinical trial design. Materials/

Methods: Based on results of a working group literature summary a 2-tier Delphi-consensus process of 24 physician and physics experts from 3 European countries was conducted. Degree of consensus was predefined for overarching (OA) and organ specific (OS) statements (=80%, 60-79%, <60% for high, intermediate and poor consensus). Post first round, statements were refined in a live discussion with 125 participants for the second round of the Delphi process.
Results: Experts consented on a total of 14 OA and 17 OS statements of SBRT of primary and secondary lung as well as liver, pancreas, adrenal and kidney tumors. Degree of consent was =80% in 79% and 41% of OA and OS statements, respectively, with higher consensus for lung compared to upper abdomen. In round 2, degree of consent =80% increased to 100% for OA and 88% in OS statements. No consensus was reached for dose escalation of liver metastases after chemotherapy (47%) and single fraction SBRT for kidney primaries (13%). In round 2, no statements had 60-79% consensus.
Conclusion: In 29 of 31 statements a high consensus was achieved after a 2-tier Delphi process, and 1 statement (kidney) was clearly refused. The Delphi process was able to achieve a high degree of consensus for dose prescription of SBRT. In summary, clear recommendations for both OA and OS could be defined. This contributes significantly to harmonization and for the design of clinical trials in SBRT. Specific exemplary cases will be deducted from the statements in the next step.

Category	Topic	Statements (n)	Range of Consent
Overarching	Dose prescription	5	86-100%
	Beam Technique Planning	4	94-100%
	Dose Calculation	3	88-100%
	Documentation	2	100%
Organ specific	Lung	3	93-94%
	Liver	8	47-100%
	Pancreatic	2	88-100%
	Renal	2	13-100%
	Adrenal	2	85-94%