Plan Quality Assessment of Fractionated Stereotactic Radiotherapy Treatment Plans in Patients With Brain Metastases

Mihály Simon; Judit Papp; Emese Csiki; Árpád Kovács

doi:10.3389/fonc.2022.846609

Plan Quality Assessment of Fractionated Stereotactic Radiotherapy Treatment Plans in Patients With Brain Metastases

Front Oncol. 2022 Mar 8:12:846609. doi: 10.3389/fonc.2022.846609. eCollection 2022.

Authors

Mihály Simon^{1

2}, Judit Papp^{1

2}, Emese Csiki¹, Árpád Kovács^{1

2}

Affiliations

¹ Department of Oncoradiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
² Doctoral School of Health Sciences, University of Pécs Faculty of Health Sciences, Pécs, Hungary.

Abstract

Background and purpose: The treatment options available in the management of brain metastases includes fractionated stereotactic radiotherapy (FSRT) and stereotactic radiosurgery (SRS) treatments. FSRT treatments have proved to be useful mainly in the treatment of larger volumes. This study aims to evaluate the FSRT treatment technique used in our department based on various plan quality indices.

Methods and materials: 24 treatment plans of 23 patients were analyzed. Volumetric modulated arc therapy (VMAT) plans were generated in line with the department protocol. The following parameters were extracted: Radiation Therapy Oncology Group conformity index (RTOG CI), Paddick conformity index (Paddick CI), gradient index (GI), quality index (Q), homogeneity index (HI), and V24.4 volume as a parallel index of V12 used at SRS plan evaluation.

Results: Plan conformity was acceptable, RTOG CI mean was 0.942; Paddick CI mean was 0.824. The mean GI value was 6.146. The mean of HI and Q indices were 1.263 and 0.94, respectively. V24.4 mean was 33.434 cm³. All plans achieved clinically acceptable organs-at-risk (OAR) constraints. PTV volumes were clustered into either 10 cm³ or 15 cm³ bins depending on the plan quality metric we used. The mean values show a balanced distribution of plan indices along the various PTV bins.

Discussion: Our results based on the derived indices show that our FSRT approach can achieve clinically acceptable treatment plans. Furthermore, the clustering of PTV volumes show that these plan quality metrics remain acceptable for a wide spectrum of PTV volumes.

Keywords: FSRT = fractionated stereotactic radiotherapy; VMAT = volumetric modulated arc therapy; brain metastases; conformity index (CI); linac based.