title: Development of a novel method to enhance the therapeutic effect on tumours by simultaneous action of radiation and heating.
abstract: OBJECTIVE
  This paper describes the development of a new type of electromagnetic hyperthermia applicator delivering dose control within large application fields and increased effectiveness by providing simultaneous action of radiation and heating (SRH) in malignant tumours, and development of a dosimetric feedback method to support SRH.
  
  
  METHODS
  Single and phased arrays of flexible applicators have been developed to allow simultaneous hyperthermia and external beam therapy. A frequency of 434 MHz is used to heat near-surface and moderately deep-seated tumours and 70 MHz for deep-seated tumours. Phase and amplitude control allows focusing of electromagnetic energy (EM) to deep-seated tumours. The specific absorption rate (SAR) dose distribution can be modified to achieve uniform heating of tumours with complex shapes and heterogeneous tissue properties. A lithium fluoride thermoluminescent dosimeter (TLD) in a flexible film cassette has been developed for real-time dose measurement.
  
  
  RESULTS
  Four types of 434 MHz applicators were manufactured with 3, 4, 9 or 12 independent applicators. Two types of 70 MHz applicators were made with 4 or 6 independent applicators. Phantom tests demonstrated the ability to control the SAR pattern by phase and amplitude control. Placement of the dosimeter between bolus and phantom increased the phantom surface temperature up to 3 °C and showed that the ratio of absorbed energy in TLD to dose in water approaches (0.83 ± 3%) for photon energies >60 keV.
  
  
  CONCLUSIONS
  Simultaneous and controlled radiation and local hyperthermia is technically feasible in a preclinical setting, a clinical feasibility test is the next step.
authors: Moscow Engineering Physics Institute (MEPhI), National Research Nuclear University , Moscow , Russia .
authors: Vladimir V
authors: VV
authors: Kosterev
authors: Evgeny A
authors: EA
authors: Kramer-Ageev
authors: Vladimir N
authors: VN
authors: Mazokhin
authors: Gerard C
authors: GC
authors: van Rhoon
authors: Johannes
authors: J
authors: Crezee
mesh_terms: D003131:Combined Modality Therapy; D055590:Electromagnetic Phenomena; D006979:Hyperthermia, Induced / Q000379:methods*; D009369:Neoplasms / Q000532:radiotherapy / Q000628:therapy*; D019047:Phantoms, Imaging; D061766:Proton Therapy / Q000379:methods*; D011874:Radiometry
keywords: Gamma radiation; TLD dose monitor; hyperthermia; phased array; radiofrequency/microwave; simultaneous radiation and heating