Use of a novel atlas for muscles of mastication to reduce inter observer variability in head and neck radiotherapy contouring

Christina Hague; William Beasley; Lynne Dixon; Simona Gaito; Kate Garcez; Andrew Green; Lip W Lee; Massimo Maranzano; Andrew McPartlin; Hitesh Mistry; Damian Mullan; Andrew J Sykes; David Thomson; Marcel Van Herk; Catharine M West; Nick Slevin

doi:10.1016/j.radonc.2018.10.030

Use of a novel atlas for muscles of mastication to reduce inter observer variability in head and neck radiotherapy contouring

Radiother Oncol. 2019 Jan:130:56-61. doi: 10.1016/j.radonc.2018.10.030. Epub 2018 Nov 9.

Authors

Christina Hague¹, William Beasley², Lynne Dixon³, Simona Gaito⁴, Kate Garcez⁵, Andrew Green⁶, Lip W Lee⁷, Massimo Maranzano⁸, Andrew McPartlin⁹, Hitesh Mistry¹⁰, Damian Mullan¹¹, Andrew J Sykes¹², David Thomson¹³, Marcel Van Herk¹⁴, Catharine M West¹⁵, Nick Slevin¹⁶

Affiliations

¹ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
² Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Heath, University of Manchester, Manchester Academic Health Science Centre, UK. Electronic address: [email protected].
³ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
⁴ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
⁵ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
⁶ Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Heath, University of Manchester, Manchester Academic Health Science Centre, UK; Department of Radiotherapy Related Research, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
⁷ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
⁸ Department of Oral-Maxillo-Facial and Plastic Reconstructive Surgery, Central Manchester University Hospitals, UK. Electronic address: [email protected].
⁹ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
¹⁰ Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Heath, University of Manchester, Manchester Academic Health Science Centre, UK. Electronic address: [email protected].
¹¹ Department of Radiology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
¹² Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
¹³ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
¹⁴ Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Heath, University of Manchester, Manchester Academic Health Science Centre, UK; Department of Radiotherapy Related Research, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].
¹⁵ Translational Radiobiology Group, Division of Cancer Sciences, Manchester Academic Health Science Centre, University of Manchester, The Christie NHS Foundation Trust, UK. Electronic address: [email protected].
¹⁶ Department of Head and Neck Clinical Oncology, The Christie NHS Foundation Trust, Manchester, UK. Electronic address: [email protected].

PMID: 30420234
DOI: 10.1016/j.radonc.2018.10.030

Abstract

Purpose/objective(s): Trismus is caused by injury to the masticatory muscles resulting from cancer or its treatment. Contouring these muscles to reduce dose and radiation related trismus can be problematic due to interobserver variability. This study aimed to evaluate the reduction in interobserver variability achievable with a new contouring atlas.

Materials/methods: The atlas included: medial and lateral pterygoids (MP, LP), masseter (M) and temporalis (T) muscles, and the temporo-mandibular joint (TMJ). Seven clinicians delineated five paired structures on CT scans from 5 patients without the atlas. After ≥5 weeks, contouring was repeated using the atlas. Using contours generated by the clinicians on the same 5 CT scans as reference, dice similarity coefficient (DSC), mean distance-to-agreement (DTA) and centre of mass (COM) difference were compared with and without the atlas. Comparison was also performed split by training grade. Mean and standard deviation (SD) values were measured.

Results: The atlas reduced interobserver variability for all structures. Mean DTA significantly improved for MP (p = 0.01), M (p < 0.01), T (p < 0.01) and TMJ (p < 0.01). Mean DTA improved using the atlas for the trainees across all muscles, with the largest reduction in variability observed for the T (4.3 ± 7.1 v 1.2 ± 0.4 mm, p = 0.06) and TMJ (2.1 ± 0.7 v 0.8 ± 0.3 mm, p < 0.01). Distance between the COM and interobserver variability reduced in all directions for MP and T.

Conclusion: A new atlas for contouring masticatory muscles during radiotherapy planning for head and neck cancer reduces interobserver variability and could be used as an educational tool.

Keywords: Atlas; Contouring; Interobserver variability; Radiotherapy; Trismus.

MeSH terms

Female
Head and Neck Neoplasms / diagnostic imaging
Head and Neck Neoplasms / radiotherapy*
Humans
Mastication
Masticatory Muscles / anatomy & histology*
Masticatory Muscles / diagnostic imaging
Masticatory Muscles / radiation effects
Neck / anatomy & histology
Neck / diagnostic imaging
Observer Variation
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy Planning, Computer-Assisted / standards
Tomography, X-Ray Computed / methods