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Finished - Clinical value of 3D-SAR planning for deep HT

In this project, the clinical value of 3D-SAR planning wll be assessed during loco-regional hyperthermia of cervical cancer using the BSD2000-3D system.

Sponsor

  Dutch Cancer Society, grant DDHK2007-2884


Background
In the Netherlands, loco-regional hyperthermia in addition to radiotherapy is considered regular health care within the frame of the Dutch National Health Service for patients with advanced stages of cervical cancer. Yearly, a growing number of these patients are referred to us for hyperthermia treatment. The current third generation equipment for loco-regional hyperthermia has substantially increased our ability to adapt the SAR distribution in the patient. Still a common area of concern is the frequent occurrence of local hot spots, which are limiting the treatment quality due to discomfort or pain. In these situations SAR-steering is experienced as a very useful aid to enhance the quality of the hyperthermia treatment. For maximum exploitation of the SAR steering feasibility the use of a hyperthermia treatment planning system (HTPS) is advocated as being a prerequisite to guide the selection of the best phase and amplitude settings.

Purpose
The purpose of this project is to quantitatively assess the value of SAR-treatment planning as an aid to the hyperthermia treatment. Hereto the quality of loco-regional hyperthermia treatments applied with the Sigma 60 applicator of the BSD2000-3D hyperthermia system with or without the guidance of SAR-treatment planning will be measured and compared.


Figure 1: Controller room of the deep hyperthermia treatment with the BSD2000 system in the background.

Plan of investigation
The clinical value of both 3D-SAR treatment planning systems will be assessed by making intra- and inter-patient comparisons of the quality of the hyperthermia treatment. In this way the number of patients required to perform the study is limited. The study design is as follows: we will perform a clinical study in which for two treatments, either the 2nd and 4th or the 3rd and 5th, the information on the SAR distribution, obtained from the treatment planning software, will be used to guide the phase and amplitude settings during the hyperthermia treatment. The other two treatments, 3rd and 5th or 2nd and 4th, will applied according our standard treatment protocol. The order of the treatments will be selected randomly. Treatment planning will be performed with finite element method software with a tetrahedral grid, e.g. Sigma Hyperplan. The study will involve 36 patients. Primary endpoints are measured tumor temperatures and patient comfort during treatment.


Figure 2: An example of a patient model (left) and an optimized SAR-distribution, calculated with this model (right)

Preliminary results
A data base structure is realized to collect all available data through a uniform and where possible automatic registration. As part of this structure a new software module, the Hyperthermia Data Center, has been developed to improve data acquisition and analysis, and optimization of SAR-distributions. The Hyperthermia Data Center consists of:

  • The RHyThM (Rotterdam Hyperthermia Thermal Modulator) platform has been developed. This program provides the key to improved access of the treatment data as registered by the BSD2000-3D hyperthermia system. Important features of RHyThM are the ability to perform an integrity check on the recorded temperature data and to make the RF-power data available or analysis on for instance applied SAR or deduce information on local blood perfusion.
  • A registration sheet, on which patient remarks and discomfort can be entered in a standardized way.
  • A power monitoring system, functioning independently from the heating equipment.
  • An optimization tool, that enables model-guided steering of the treatment, based on the calculated SAR-distribution.


Figure 3: Temperature analysis in the Rhythm software

Contact
GC van Rhoon