title: Theoretical comparison of intraluminal heating techniques.
abstract: BACKGROUND
  This study compared simulated temperature distributions of intraluminal heating devices, concerning penetration and homogeneity. A hot water balloon, a 434-MHz monopole and a 915-MHz dipole antenna, both with incorporated cooling, and a 27-MHz applicator were investigated.
  
  
  METHODS
  The hot water balloon had an inlet temperature of 45 degrees C and a flow rate of 7.85 ml s(-1). The cooling water and air had a temperature of 41 degrees C and 37 degrees C and a flow rate of 5.89 ml s(-1) and 1.8 l s(-1), respectively. A 27-MHz applicator consisting of one or two electrode(s) was modelled to demonstrate axial steering for inhomogeneous tissue properties. Calculated power distributions were scaled to a total power of 10 W in tissue before the corresponding temperature distributions were calculated.
  
  
  RESULTS
  The hot water balloon and the 27-MHz device showed a thermal penetration depth of approximately 4 and approximately 10 mm, respectively. The penetration depths of the 434- and 915-MHz applicators were comparable: approximately 10 and approximately 16 mm with water and air cooling, respectively. With the 27-MHz applicator, spatial steering was applied to minimize temperature gradients along the applicator. The 434- and 915-MHz antennas have no steering possibilities. The temperature distribution of the hot water balloon is not affected by inhomogeneous dielectric properties, only slightly by inhomogeneous perfusion.
  
  
  CONCLUSIONS
  A hot water balloon is useful for heating tumours with a limited infiltration in tissue, while a 27-MHz device has the best potential to realize a homogeneous temperature distribution in larger tumours.
authors.affiliation: Department of Radiation Oncology, University of Amsterdam, The Netherlands. h.p.kok@amc.uva.nl
authors.forename: H P
authors.initials: HP
authors.lastname: Kok
authors.forename: P M A
authors.initials: PM
authors.lastname: van Haaren
authors.forename: J B
authors.initials: JB
authors.lastname: van de Kamer
authors.forename: J
authors.initials: J
authors.lastname: Crezee
mesh_terms: D003080:Cold Temperature; D004566:Electrodes; D004867:Equipment Design; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods* / Q000451:nursing*; D008962:Models, Theoretical