Accurate 3D temperature dosimetry during hyperthermia therapy by combining invasive measurements and patient-specific simulations

René F. Verhaart, Gerda M. Verduijn, Valerio Fortunati, Zef Rijnen, Theo van Walsum, Jifke F. Veenland, Margarethus M. Paulides

Research output: Contribution to journalArticleAcademicpeer-review

30 Citations (Scopus)
63 Downloads (Pure)

Abstract

PURPOSE: Dosimetry during deep local hyperthermia treatments in the head and neck currently relies on a limited number of invasively placed temperature sensors. The purpose of this study was to assess the feasibility of 3D dosimetry based on patient-specific temperature simulations and sensory feedback.

MATERIALS AND METHODS: The study includes 10 patients with invasive thermometry applied in at least two treatments. Based on their invasive thermometry, we optimised patient-group thermal conductivity and perfusion values for muscle, fat and tumour using a 'leave-one-out' approach. Next, we compared the accuracy of the predicted temperature (ΔT) and the hyperthermia treatment quality (ΔT50) of the optimisations based on the patient-group properties to those based on patient-specific properties, which were optimised using previous treatment measurements. As a robustness check, and to enable comparisons with previous studies, we optimised the parameters not only for an applicator efficiency factor of 40%, but also for 100% efficiency.

RESULTS: The accuracy of the predicted temperature (ΔT) improved significantly using patient-specific tissue properties, i.e. 1.0 °C (inter-quartile range (IQR) 0.8 °C) compared to 1.3 °C (IQR 0.7 °C) for patient-group averaged tissue properties for 100% applicator efficiency. A similar accuracy was found for optimisations using an applicator efficiency factor of 40%, indicating the robustness of the optimisation method. Moreover, in eight patients with repeated measurements in the target region, ΔT50 significantly improved, i.e. ΔT50 reduced from 0.9 °C (IQR 0.8 °C) to 0.4 °C (IQR 0.5 °C) using an applicator efficiency factor of 40%.

CONCLUSION: This study shows that patient-specific temperature simulations combined with tissue property reconstruction from sensory data provides accurate minimally invasive 3D dosimetry during hyperthermia treatments: T50 in sessions without invasive measurements can be predicted with a median accuracy of 0.4 °C.

Original languageEnglish
Pages (from-to)686-692
Number of pages7
JournalInternational Journal of Hyperthermia
Volume31
Issue number6
DOIs
Publication statusPublished - 2015

Keywords

  • Head and Neck Neoplasms/therapy
  • Humans
  • Hyperthermia, Induced
  • Patient-Specific Modeling
  • Temperature
  • Thermometry

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