Results of Deep Body Hyperthermia with Large Waveguide Radiators

Dijk, J.D.P. van; Schneider, Christoph; Os, Rob van; Blank, L.E.C.M.; González, Dionisio González

doi:10.1007/978-1-4684-5766-7_31

Cited by 57 publications

(42 citation statements)

References 2 publications

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“…The HT treatment is given using the 70 MHz AMC-4 phased array system [24]. During 11 treatment sessions in seven patients extensive (minimally) invasive thermometry was applied as well as pre-treatment CT scans for verification of HTP.…”

Section: Hyperthermia Treatments and Measurementsmentioning

confidence: 99%

On verification of hyperthermia treatment planning for cervical carcinoma patients

Haaren

Kok

Berg

et al. 2007

International Journal of Hyperthermia

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Section: Hyperthermia Treatments and Measurementsmentioning

confidence: 99%

On verification of hyperthermia treatment planning for cervical carcinoma patients

Haaren

Kok

Berg

et al. 2007

International Journal of Hyperthermia

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“…One of the sites where hyperthermia is applied is the pelvic area. In order to achieve su cient heating for the deep-seated tumours located at this site, systems have been designed that coherently radiate radio frequency (RF) energy towards the patient from di erent directions [1][2][3] . These systems are known as phased array systems.…”

Section: Introductionmentioning

confidence: 99%

A flexible optimization tool for hyperthermia treatments with RF phased array systems

Wiersma

Maarseveen

Dijk

2002

International Journal of Hyperthermia

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In hyperthermia treatments performed with a radio-frequency phased array, the main issue to apply the excitation amplitudes and phases of the applicators for which tumour heating is optimal, i.e. the maximal therapeutic gain without unwanted side effects. Due to the complex interaction of the radiated EM-field and the patient's tissues, it is very difficult to find these optimal excitation (amplitude and phase) parameters by intuition. Calculation of the EM-field distribution within the patient can aid in finding the optimal excitation setting. However, this remains a difficult task because of the degrees of freedom available (2n - 1, with n the number of applicators in the array) and because a large temperature elevation may occur at healthy tissue sites resulting in unwanted side effects, e.g. pain or healthy tissue damage. Therefore, determining the excitation amplitudes and phases yielding optimal tumour heating can be done effectively only by application of a computerized optimization procedure. Optimization of the temperature distribution in the patient requires detailed knowledge of the thermal tissue parameters. Techniques for determining these properties are not commonly available and the use of averaged values for parameters like the tissue perfusion is expected to introduce large errors for individual patient treatment planning. As a consequence, the SAR distribution, being proportional to the temperature increase at treatment start, is more often selected for optimization. The 'optimized' excitation amplitudes and phases are found by maximization of a certain SAR ratio. Several propositions for this SAR ratio have been reported in the literature, e.g. the ratio of the SAR at the tumour site and the SAR at sites where unwanted side effects may occur. However, the definition of these ratios does not constrain the SAR value at these tissue locations to a safe value. In this paper, a tool for the optimization of the SAR distribution including the specification of constraints is presented. The tool focuses on the definition of the average SAR as a function of the excitation amplitudes and phases in a volume of arbitrary size (e.g. the tumour volume or the whole patient volume). These functions can be applied in either customized or commercially available optimization routines and they enable the definition of constraints for the average SAR in a certain volume. The described tool is illustrated for a patient case, showing the flexibility and easy application of the tool.

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“…[9][10][11] Treatment planning that enhances the ability to focus heat at the bladder has also been reported. For example, van Dijk et al 12 showed increased bladder SAR using treatment planning to optimize the SAR distribution in a selected two-dimensional plane. However, the treatment planning software developed by van Dijk et al, 12 also used by Rietbroek et al, 13 restricted optimization to a single plane.…”

Section: Introductionmentioning

confidence: 99%

“…For example, van Dijk et al 12 showed increased bladder SAR using treatment planning to optimize the SAR distribution in a selected two-dimensional plane. However, the treatment planning software developed by van Dijk et al, 12 also used by Rietbroek et al, 13 restricted optimization to a single plane. It was not possible with this planning method to evaluate the treatment using three dimensional (3D) treatment statistics of the target temperatures or hot spot occurrences in normal tissues.…”

Section: Introductionmentioning

confidence: 99%

Utility of treatment planning for thermochemotherapy treatment of nonmuscle invasive bladder carcinoma

et al. 2012

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Purpose: A recently completed Phase I clinical trial combined concurrent Mitomycin-C chemotherapy with deep regional heating using BSD-2000 Sigma-Ellipse applicator (BSD Corporation, Salt Lake City, UT, U.S.A.) for the treatment of nonmuscle invasive bladder cancer. This work presents a new treatment planning approach, and demonstrates potential impact of this approach on improvement of treatment quality. Methods: This study retrospectively analyzes a subset of five patients on the trial. For each treatment, expert operators selected "clinical-optimal" settings based on simple model calculation on the BSD-2000 control console. Computed tomography (CT) scans acquired prior to treatment were segmented to create finite element patient models for retrospective simulations with SigmaHyperPlan (Dr. Sennewald Medizintechnik GmbH, Munchen, Germany). Since Sigma-HyperPlan does not account for the convective nature of heat transfer within a fluid filled bladder, an effective thermal conductivity for bladder was introduced. This effective thermal conductivity value was determined by comparing simulation results with clinical measurements of bladder and rectum temperatures. Regions of predicted high temperature in normal tissues were compared with patient complaints during treatment. Treatment results using "computed-optimal" settings from the planning system were compared with clinical results using clinical-optimal settings to evaluate potential of treatment improvement by reducing hot spot volume. Results: For all five patients, retrospective treatment planning indicated improved matches between simulated and measured bladder temperatures with increasing effective thermal conductivity. The differences were mostly within 1.3 C when using an effective thermal conductivity value above 10 W/K/m. Changes in effective bladder thermal conductivity affected surrounding normal tissues within a distance of $1.5 cm from the bladder wall. Rectal temperature differences between simulation and measurement were large due to sensitivity to the sampling locations in rectum. The predicted bladder T90 correlated well with single-point bladder temperature measurement. Hot spot locations predicted by the simulation agreed qualitatively with patient complaints during treatment. Furthermore, comparison between the temperature distributions with clinical and computedoptimal settings demonstrated that the computed-optimal settings resulted in substantially reduced hot spot volumes. Conclusions: Determination of an effective thermal conductivity value for fluid filled bladder was essential for matching simulation and treatment temperatures. Prospectively planning patients using the effective thermal conductivity determined in this work can potentially improve treatment efficacy (compared to manual operator adjustments) by potentially lower discomfort from reduced hot spots in normal tissue.

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Results of Deep Body Hyperthermia with Large Waveguide Radiators

Cited by 57 publications

References 2 publications

On verification of hyperthermia treatment planning for cervical carcinoma patients

On verification of hyperthermia treatment planning for cervical carcinoma patients

A flexible optimization tool for hyperthermia treatments with RF phased array systems

Utility of treatment planning for thermochemotherapy treatment of nonmuscle invasive bladder carcinoma

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