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High-resolution temperature-based optimization for hyperthermia treatment planning.
- Source :
-
Physics in medicine and biology [Phys Med Biol] 2005 Jul 07; Vol. 50 (13), pp. 3127-41. Date of Electronic Publication: 2005 Jun 22. - Publication Year :
- 2005
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Abstract
- In regional hyperthermia, optimization techniques are valuable in order to obtain amplitude/phase settings for the applicators to achieve maximal tumour heating without toxicity to normal tissue. We implemented a temperature-based optimization technique and maximized tumour temperature with constraints on normal tissue temperature to prevent hot spots. E-field distributions are the primary input for the optimization method. Due to computer limitations we are restricted to a resolution of 1 x 1 x 1 cm3 for E-field calculations, too low for reliable treatment planning. A major problem is the fact that hot spots at low-resolution (LR) do not always correspond to hot spots at high-resolution (HR), and vice versa. Thus, HR temperature-based optimization is necessary for adequate treatment planning and satisfactory results cannot be obtained with LR strategies. To obtain HR power density (PD) distributions from LR E-field calculations, a quasi-static zooming technique has been developed earlier at the UMC Utrecht. However, quasi-static zooming does not preserve phase information and therefore it does not provide the HR E-field information required for direct HR optimization. We combined quasi-static zooming with the optimization method to obtain a millimetre resolution temperature-based optimization strategy. First we performed a LR (1 cm) optimization and used the obtained settings to calculate the HR (2 mm) PD and corresponding HR temperature distribution. Next, we performed a HR optimization using an estimation of the new HR temperature distribution based on previous calculations. This estimation is based on the assumption that the HR and LR temperature distributions, though strongly different, respond in a similar way to amplitude/phase steering. To verify the newly obtained settings, we calculate the corresponding HR temperature distribution. This method was applied to several clinical situations and found to work very well. Deviations of this estimation method for the AMC-4 system were typically smaller than 0.2 degrees C in the volume of interest, which is accurate enough for treatment planning purposes.
- Subjects :
- Body Burden
Body Temperature
Computer Simulation
Dose-Response Relationship, Radiation
Esophageal Neoplasms physiopathology
Humans
Radiotherapy Dosage
Relative Biological Effectiveness
Esophageal Neoplasms therapy
Hyperthermia, Induced methods
Microwaves therapeutic use
Models, Biological
Radiometry methods
Radiotherapy Planning, Computer-Assisted methods
Thermography methods
Subjects
Details
- Language :
- English
- ISSN :
- 0031-9155
- Volume :
- 50
- Issue :
- 13
- Database :
- MEDLINE
- Journal :
- Physics in medicine and biology
- Publication Type :
- Academic Journal
- Accession number :
- 15972985
- Full Text :
- https://doi.org/10.1088/0031-9155/50/13/011