title: Optimisation of the coagulation zone for thermal ablation procedures: a theoretical approach with considerations for practical use.
abstract: OBJECTIVE
  This paper outlines a theoretical approach for optimisation of the coagulation zone for thermal ablation procedures and considerations for its practical application.
  
  
  METHODS
  The theoretical approach is outlined in the Cartesian coordinate system. Considerations for practical application are implemented. The optimised coagulation zone is defined as the bare coverage of tumour mass plus a safety margin. The eccentricity of coagulation centre (ECC) is defined as the distance between the coagulation centre and the tumour centre. The direction of the applicator shaft is determined based on the x-axis direction. The tumour centre and coagulation centre are defined within the x/y-plane. The distance between coagulation margin (applicator tip) and tumour margin is called parallel offset (PAO).
  
  
  RESULTS
  For spherical coagulation shapes, a linear relationship exists between optimised coagulation diameter and ECC. An exponential relationship exists between optimised coagulation volume and ECC. A complex relationship was found between PAO and determinants of ECC, which are ex and ey. PAO is an extremely important parameter, which allows for determination of the optimal applicator tip position in relation to the tumour margin. It can be calculated in such a manner that the optimised coagulation zone is minimised by neutralising dislocation of the coagulation centre in applicator shaft direction. The latter can be realised by withdrawing or further inserting the applicator shaft.
  
  
  CONCLUSIONS
  The presented concept can be used to optimise the extent of the coagulation zone for thermal ablation procedures after positioning of the applicator. Its inherent advantage is the simple adjustment of the applicator shaft, which obviates the need for a repuncture.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital , Heidelberg , Germany .
authors.forename: Christof M
authors.initials: CM
authors.lastname: Sommer
authors.forename: Steffen A
authors.initials: SA
authors.lastname: Sommer
authors.forename: Werner O
authors.initials: WO
authors.lastname: Sommer
authors.forename: Sascha
authors.initials: S
authors.lastname: Zelzer
authors.forename: Maya B
authors.initials: MB
authors.lastname: Wolf
authors.forename: Nadine
authors.initials: N
authors.lastname: Bellemann
authors.forename: Hans P
authors.initials: HP
authors.lastname: Meinzer
authors.forename: Boris A
authors.initials: BA
authors.lastname: Radeleff
authors.forename: Ulrike
authors.initials: U
authors.lastname: Stampfl
authors.forename: Hans U
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Philippe L
authors.initials: PL
authors.lastname: Pereira
mesh_terms: D001777:Blood Coagulation; D006979:Hyperthermia, Induced; D008962:Models, Theoretical; D009369:Neoplasms / Q000097:blood / Q000628:therapy*