Johannes Crezee

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Hyperthermia treatment planning (HTP) is an important tool to improve the quality of hyperthermia treatment. It is a practical way of designing new hyperthermia systems and can be used to optimize the phase and amplitude settings to achieve optimal heating. One of the main challenges to be dealt with however is the uncertainty in the modeling parameters.(More)
The verification of thermal models for use in hyperthermia treatment planning is essential. We investigated the heat transfer between a single vessel and the surrounding vascularised tissue, comparing the conventional bioheat transfer theory and the recently developed keff model using analytical and numerical methods. A plastic tube inserted into the tissue(More)
The linear-quadratic model (LQ model) provides a biologically plausible and experimentally established method to quantitatively describe the dose-response to irradiation in terms of clonogenic survival. In the basic LQ formula, the clonogenic surviving fraction Sd/S₀ following a radiation dose d (Gy) is described by an inverse exponential approximation:(More)
Scanned focused ultrasound (SFUS) is unique amongst noninvasive methods of inducing hyperthermia in that the absorbed power (SAR) distribution may be controlled at a scale of 0.5 cm or better. This high degree of spatial control of SAR implies that differences in local tissue cooling due to heterogeneity in perfusion, variations in the density of discrete(More)
INTRODUCTION Regional hyperthermia systems with 3D power steering have been introduced to improve tumour temperatures. The 3D 70-MHz AMC-8 system has two rings of four waveguides. The aim of this study is to evaluate whether T(90) will improve by using a higher operating frequency and whether further improvement is possible by adding a third ring. METHODS(More)
PURPOSE Accurate thermal simulations in hyperthermia treatment planning require discrete modeling of large blood vessels. The very long computation time of the finite difference based DIscrete VAsculature model (DIVA) developed for this purpose is impractical for clinical applications. In this work, a fast steady-state thermal solver was developed for(More)
The in vivo electric conductivity (σ) values of tissue are essential for accurate electromagnetic simulations and specific absorption rate (SAR) assessment for applications such as thermal dose computations in hyperthermia. Currently used σ-values are mostly based on ex vivo measurements. In this study the conductivity of human muscle, bladder content and(More)
OBJECTIVE Early detection of peritoneal metastases (PM) of colorectal cancer (CRC) is difficult and treatment options at a clinically overt stage are limited. Potentially, adjuvant laparoscopic hyperthermic intraperitoneal chemotherapy (HIPEC) is of value. The aim of this study was to present long term oncological outcomes of a pilot study on adjuvant HIPEC(More)
Introduction The reliability of hyperthermia treatment planning (HTP) is strongly dependent on the accuracy of the electric properties of each tissue. The values currently used are mostly based on ex vivo measurements. In this study, in vivo conductivity of human muscle, bladder content and cervical tumours, acquired with magnetic resonance-based electric(More)
Accurate treatment planning is necessary for the successful application of hyperthermia in the clinic. The validity of four different bioheat models or combinations of models is evaluated: the conventional bioheat transfer equation, the limited effective conductivity model, a mixed heat sink-effective conductivity model and a discrete vessel model. The heat(More)