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Nour Y, Pöttgen C, Kebir S, Lazaridis L, Lüdemann L, Guberina M, Gauler T, Scheffler B, Jabbarli R, Pierscianek D, Sure U, Schmidt T, Oster C, Hau P, Glas M, Lübcke W, Stuschke M, Guberina N. Dosimetric impact of the positioning variation of tumor treating field electrodes in the PriCoTTF-phase I/II trial. J Appl Clin Med Phys 2021; 22:242-250. [PMID: 33389825 PMCID: PMC7856507 DOI: 10.1002/acm2.13144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/06/2020] [Accepted: 12/04/2020] [Indexed: 12/25/2022] Open
Abstract
Purpose The aim of the present study based on the PriCoTTF‐phase I/II trial is the quantification of skin‐normal tissue complication probabilities of patients with newly diagnosed glioblastoma multiforme treated with Tumor Treating Field (TTField) electrodes, concurrent radiotherapy, and temozolomide. Furthermore, the skin‐sparing effect by the clinically applied strategy of repetitive transducer array fixation around their center position shall be examined. Material and Methods Low‐dose cone‐beam computed tomography (CBCT) scans of all fractions of the first seven patients of the PriCoTTF‐phase I/II trial, used for image guidance, were applied for the dosimetric analysis, for precise TTField transducer array positioning and contour delineation. Within this trial, array positioning was varied from fixation‐to‐fixation period with a standard deviation of 1.1 cm in the direction of the largest variation of positioning and 0.7 cm in the perpendicular direction. Physical TTField electrode composition was examined and a respective Hounsfield Unit attributed to the TTField electrodes. Dose distributions in the planning CT with TTField electrodes in place, as derived from prefraction CBCTs, were calculated and accumulated with the algorithm Acuros XB. Dose‐volume histograms were obtained for the first and second 2 mm scalp layer with and without migrating electrodes and compared with those with fixed electrodes in an average position. Skin toxicity was quantified according to Lyman's model. Minimum doses in hot‐spots of 0.05 cm2 and 25 cm2 (ΔD0.05cm2, ΔD25cm2) size in the superficial skin layers were analyzed. Results Normal tissue complication probabilities (NTCPs) for skin necrosis ranged from 0.005% to 1.474% (median 0.111%) for the different patients without electrodes. NTCP logarithms were significantly dependent on patient (P < 0.0001) and scenario (P < 0.0001) as classification variables. Fixed positioning of TTField arrays increased skin‐NTCP by a factor of 5.50 (95%, CI: 3.66–8.27). The variation of array positioning increased skin‐NTCP by a factor of only 3.54 (95%, CI: 2.36–5.32) (P < 0.0001, comparison to irradiation without electrodes; P = 0.036, comparison to irradiation with fixed electrodes). NTCP showed a significant rank correlation with D25cm2 over all patients and scenarios (rs = 0.76; P < 0.0001). Conclusion Skin‐NTCP calculation uncovers significant interpatient heterogeneity and may be used to stratify patients into high‐ and low‐risk groups of skin toxicity. Array position variation may mitigate about one‐third of the increase in surface dose and skin‐NTCP by the TTField electrodes.
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Affiliation(s)
- Youness Nour
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Christoph Pöttgen
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Sied Kebir
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Lazaros Lazaridis
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Lutz Lüdemann
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Maja Guberina
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Thomas Gauler
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Björn Scheffler
- DKFZ-Division Translational Neurooncology at the West German Cancer Centre (WTZ), German Cancer Consortium (DKTK), Partner Site University Hospital Essen, University of Duisburg, Essen, Germany.,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany
| | - Ramazan Jabbarli
- Department of Neurosurgery, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Daniela Pierscianek
- Department of Neurosurgery, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Ulrich Sure
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany.,Department of Neurosurgery, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Teresa Schmidt
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Christoph Oster
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Peter Hau
- Department of Neurology and Wilhelm Sander-NeuroOncology Unit, Regensburg University Hospital, Germany
| | - Martin Glas
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany.,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany
| | - Wolfgang Lübcke
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Martin Stuschke
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany.,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany
| | - Nika Guberina
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
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