title: Improving hyperthermia treatment planning for the pelvis by accurate fluid modeling.
abstract: OBJECTIVE
  Hyperthermia is an established (neo)adjuvant treatment modality for a number of pelvic malignancies. Optimal treatment of these tumors requires robust treatment planning, but up until now, the urinary bladder was not modeled accurately, making current simulations less reliable. The authors improved the dielectric and thermophysical model of the urinary bladder in their treatment planning system, and showed the improvements using phantom experiments.
  
  
  METHODS
  The authors suspended a porcine bladder in muscle tissue equivalent gel and filled it with 120 ml 0.9% saline. The authors heated the phantom during 15 min with their deep hyperthermia device, using clinical settings, and measured the temperature both inside and outside the bladder. The authors simulated the experiment, both using the clinically used treatment planning system, and using the improved model featuring correct dielectric properties for the bladder content and an enhanced thermophysical model, enabling the simulation of convection.
  
  
  RESULTS
  Although the dielectric changes have an impact throughout the phantom, the dominant effect is a higher net heat absorption in the bladder. The effects of changing the thermophysical model are limited to the bladder and its surroundings, but result in a very different temperature profile. The temperatures predicted by the simulations using the new bladder model were in much better agreement with the measurements than those predicted by currently used treatment planning system.
  
  
  CONCLUSIONS
  Modeling convection in the urinary bladder is very important for accurate hyperthermia treatment planning in the pelvic area.
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: G
authors: G
authors: Schooneveldt
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: H P
authors: HP
authors: Kok
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: E
authors: E
authors: Balidemaj
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: E D
authors: ED
authors: Geijsen
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: F
authors: F
authors: van Ommen
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: J
authors: J
authors: Sijbrands
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: A
authors: A
authors: Bakker
authors: Department of Urology, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: J J M C H
authors: JJ
authors: de la Rosette
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: M C C M
authors: MC
authors: Hulshof
authors: Department of Urology, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: T M
authors: TM
authors: de Reijke
authors: Department of Radiotherapy, Academisch Medisch Centrum, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: J
authors: J
authors: Crezee
mesh_terms: D000818:Animals; D006979:Hyperthermia, Induced / Q000379:methods*; D010386:Pelvic Neoplasms / Q000628:therapy; D010388:Pelvis; D019047:Phantoms, Imaging; D013552:Swine; D001743:Urinary Bladder