Improving interinstitutional and intertechnology consistency of pulmonary SBRT by dose prescription to the mean internal target volume dose

Abstract

Purpose Dose, fractionation, normalization and the dose profile inside the target volume vary substantially in pulmonary stereotactic body radiotherapy (SBRT) between different institutions and SBRT technologies. Published planning studies have shown large variations of the mean dose in planning target volume (PTV) and gross tumor volume (GTV) or internal target volume (ITV) when dose prescription is performed to the PTV covering isodose. This planning study investigated whether dose prescription to the mean dose of the ITV improves consistency in pulmonary SBRT dose distributions. Materials and methods This was a multi-institutional planning study by the German Society of Radiation Oncology (DEGRO) working group Radiosurgery and Stereotactic Radiotherapy. CT images and structures of ITV, PTV and all relevant organs at risk (OAR) for two patients with early stage non-small cell lung cancer (NSCLC) were distributed to all participating institutions. Each institute created a treatment plan with the technique commonly used in the institute for lung SBRT. The specified dose fractionation was 3 × 21.5 Gy normalized to the mean ITV dose. Additional dose objectives for target volumes and OAR were provided. Results In all, 52 plans from 25 institutions were included in this analysis: 8 robotic radiosurgery (RRS), 34 intensity-modulated (MOD), and 10 3D-conformal (3D) radiation therapy plans. The distribution of the mean dose in the PTV did not differ significantly between the two patients (median 56.9 Gy vs 56.6 Gy). There was only a small difference between the techniques, with RRS having the lowest mean PTV dose with a median of 55.9 Gy followed by MOD plans with 56.7 Gy and 3D plans with 57.4 Gy having the highest. For the different organs at risk no significant difference between the techniques could be found. Conclusions This planning study pointed out that multiparameter dose prescription including normalization on the mean ITV dose in combination with detailed objectives for the PTV and ITV achieve consistent dose distributions for peripheral lung tumors in combination with an ITV concept between different delivery techniques and across institutions.

Stereotactic body radiotherapy of adrenal metastases—A dose‐finding study

“…The wide variety of prescription patterns and doses in our study indicates that it will be important to obtain interinstitutional and intertechnology consistency in future prospective studies in the oligometastatic setting. A harmonization of planning, dose prescription, technological requirements and reporting is necessary and has already been published for example, lung metastases 41 . Such contouring and planning benchmarking is missing for adrenal metastases and is subject to further research.…”

“…This underscores the need for even larger datasets to actually detect which doses or approaches lead to long-term LC rates in potential long-term survivors. tion, technological requirements and reporting is necessary and has already been published for example, lung metastases 41. Such contouring and planning benchmarking is missing for adrenal metastases and is subject to further research.…”

Planning Benchmark Study for Stereotactic Body Radiation Therapy of Liver Metastases: Results of the DEGRO/DGMP Working Group on Stereotactic Radiation Therapy and Radiosurgery

“…1. Based on previous studies, 7,15,17,22,25,29 the prescription dose for all 3 cases was defined as median GTV dose (GTV D50% ) = 3 £ 20 Gy at the 100% isodose line (BED a/ b=10Gy = 180 Gy 10 ). Further target planning objectives were (a) GTV near maximum (ie, GTV D0.1cc ) ≤ 107% = 64.2 Gy (≤110% = 66 Gy), 23,24 (b) GTV coverage at 54 Gy (ie, GTV V90% ) 26 ≥ 98% (≥95%), and (c) PTV coverage at 42 Gy (ie, PTV V70% ) ≥ 98% (≥95%).…”

“…16,[19][20][21] Another way is the strict specification of planning goals and dose prescription, like a recent study on lung SBRT demonstrated. 22 In the lung, tissue heterogeneities are mostly responsible for discrepancies in tumor dose distribution between different patients using common circumferential planning target volume (PTV) prescription methods. 23,24 However, there is a lack of benchmark planning studies for larger tumors in more homogeneous tissue closer to critical organs at risk (OAR), like liver metastases.…”

“…In this joint planning benchmark study from the German Society for Radiation Oncology working group for radiosurgery and stereotactic radiation therapy and the German Society for Medical Physics working group for physics and technology in stereotactic radiation therapy (Deutsche Gesellschaft f€ ur Radioonkologie/ Deutsche Gesellschaft f€ ur Medizinische Physik, DEGRO/DGMP) we assessed the harmonization of treatment plan quality for liver metastases SBRT in a multi-institutional multiplatform context on an international level. Besides previous knowledge gains from the harmonization of SBRT treatment planning for lung tumors through gross tumor volume (GTV)/clinical target volume (CTV)/internal tumor/target volume mean dose prescription, 22 we implemented stricter planning goals for GTV and PTV dose coverage requirements based on recent findings on various dose-response relationships for liver metastases. 10,25,26 The aims of the present study were (1) harmonization of liver SBRT treatment plan quality for large lesions, (2) investigation on the possibility of using GTV median dose prescription in the liver, and (3) validation that the as low as reasonably achievable (ALARA) principle is better implemented after our initial planning benchmarks.…”