FDTD simulations to assess the performance of CFMA-434 applicators for superficial hyperthermia

Kok, H. Petra; Greef, Martijn de; Correia, D.; Vörding, Paul J. Zum Vörde Sive; Stam, Gerard van; Gelvich, E.A.; Bel, Arjan; Crezee, J.

doi:10.1080/02656730903008493

Cited by 31 publications

(23 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The thickness of the waterbolus for the 915 MHz CMA is set to vary between 5–10 mm to avoid SAR perturbations arising due to resonance inside the bolus (Neuman et al ., 2002; Rossetto and Stauffer, 1999). Similar observations were also reported for the 433 MHz contact flexible microstrip applicators (CFMA) used for superficial hyperthermia of chest wall recurrence and melanoma (Lee et al ., 2004; Kok et al ., 2009; Gelvich and Mazokhin, 2000). PVC thermal mapping catheters RF welded to the skin-contacting side of the water bolus enable surface temperature monitoring for feedback power control during hyperthermia treatment.…”

Section: Methodsmentioning

confidence: 99%

Thermal characteristics of thermobrachytherapy surface applicators for treating chest wall recurrence

et al. 2010

View full text Add to dashboard Cite

Purpose To study temperature and thermal dose distributions of ThermoBrachytherapy Surface Applicators (TBSA) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial disease. Methods A steady state thermodynamics model coupled with the fluid dynamics of water bolus and electromagnetic radiation of hyperthermia applicator is used to characterize the temperature distributions achievable with TBSA applicators in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm2) and L-shaped (875 cm2) TBSA. The SAR distribution in tissue and fluid flow distribution inside the Dual-Input Dual-Output (DIDO) water bolus are coupled to solve the steady state temperature and thermal dose distributions of rectangular TBSA (R-TBSA) for superficial tumor targets extending 10–15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (Tb=38–43°C), water flow rate (Qb=2–4 L/min) and tumor blood perfusion (ωb=2–5 kg/m3/s) to characterize their influence on thermal dosimetry. Results Steady state SAR patterns of R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at 2 L/min water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (Tb) to be the most influential factor on thermal dosimetry. A 42 °C water bolus was observed to be the optimal choice for superficial tumors extending 10–15 mm from the surface even under significant blood perfusion. Lower bolus temperature may be chosen to reduce thermal enhancement ratio (TER) in the most sensitive skin where maximum radiation dose is delivered and to extend thermal enhancement of radiation dose deeper. Conclusion This computational study indicates that well-localized elevation of tumor target temperature to 40–44 °C can be accomplished by large surface-conforming TBSA applicators using appropriate selection of coupling bolus temperature.

show abstract

Section: Methodsmentioning

confidence: 99%

Thermal characteristics of thermobrachytherapy surface applicators for treating chest wall recurrence

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Hyperthermia was given once a week within 1 hour after radiotherapy. Heat was induced electromagnetically, using externally applied contact flexible microstrip applicators (CFMA), operating at 434 MHz [15][16][17]. Treatment fields covered at least the area of surgery or of the recurrent tumour.…”

Section: Treatmentmentioning

confidence: 99%

Elective re-irradiation and hyperthermia following resection of persistent locoregional recurrent breast cancer: A retrospective study

Oldenborg

Rij

et al. 2010

International Journal of Hyperthermia

Self Cite

View full text Add to dashboard Cite

show abstract

“…The CFMA was modelled in the flat, unbent shape to allow good comparison with the capacitive applicators. Modelling CFMAs have been described extensively by Kok et al [19,20]. In the water bolus, deionised water is circulated and the bolus thickness is typically 1 cm [19].…”

Section: Radiative and Capacitive Systemsmentioning

confidence: 99%

A comparison of the heating characteristics of capacitive and radiative superficial hyperthermia

Kok

Crezee

2017

International Journal of Hyperthermia

View full text Add to dashboard Cite

Background: Superficial hyperthermia is applied in combination with radiotherapy for e.g. melanoma and recurrent breast cancer, using both capacitive and radiative systems. In this paper, numerical simulations are applied to address the question which technique yields the most favourable heating characteristics. Methods: A 434 MHz contact flexible microstrip applicator (CFMA type 4H, size 19.6 Â 19.6 cm 2 ) and a capacitive system consisting of two circular electrodes with diameter 15 and 25 cm were modelled. The water bolus of the CFMA was filled with deionised water and for capacitive heating both saline and deionised water were modelled. Specific absorption rate (SAR) and temperature simulations were performed for a perfused muscle-equivalent phantom and phantoms with a 1 cm thick superficial fat layer, assuming cylindrical target regions. Subsequently, a real patient model with a chest wall recurrence was studied with the target assumed to have muscle-like properties, fat properties or heterogeneous properties as derived from the CT Hounsfield Units. Results: Phantom simulations showed that high SAR peaks occur around the bolus edges with capacitive heating. Power absorption below the fat layer is substantially higher for radiative heating and unless the target region is limited to the fat layer, radiative heating yields better target coverage in terms of SAR and temperature. Patient simulations showed that the T 90 for radiative heating was 0.4-1.1 C higher compared with capacitive heating. Conclusions: Radiative heating yields more favourable SAR and temperature distributions for superficial tumours, compared with capacitive heating, especially within heterogeneous tissues. Higher tumour temperatures are achieved without occurrence of treatment limiting hot spots.

show abstract

FDTD simulations to assess the performance of CFMA-434 applicators for superficial hyperthermia

Abstract: Simulations, confirmed by measurements, showed that the presence of air between the rubber and the electrodes changes the iso-SAR contours, but the impact on the EFS and EHD is limited.

Cited by 31 publications

References 28 publications

Thermal characteristics of thermobrachytherapy surface applicators for treating chest wall recurrence

Thermal characteristics of thermobrachytherapy surface applicators for treating chest wall recurrence

Elective re-irradiation and hyperthermia following resection of persistent locoregional recurrent breast cancer: A retrospective study

A comparison of the heating characteristics of capacitive and radiative superficial hyperthermia

Contact Info

Product

Resources

About