title: [Use of megavoltage CT(MVCT) in helical tomotherapy for head and neck dose calculation].
abstract: OBJECTIVE
  To evaluate the feasibility and accuracy of using Megavoltage CT(MVCT) for head and neck dose calculation.
  
  
  METHODS
  The cheese Phantom was imaged using MVCT scanner, and the MVCT value density calibration curve was established. Conventional CT and MVCT image of nasopharyngeal carcinoma was acquired respectively, and IMRT plan was designed on conventional CT image of NPC patient. The conventional CT plan was copied to MVCT image. The dose distribution was calculated for tumor and normal tissue using the MVCT value density calibration curve, and compared with that of conventional CT. Ten NPC patients were collected for dose verification of IMRT plan on MVCT images.
  
  
  RESULTS
  The MVCT numbers depended linearly on the electron density of the sample, and the stability of the MVCT numbers to electron density was good.The error between the measured dose and calculated dose in measured point was less than 3%.The isodose distribution was well agreement with that calculated by planning system.
  
  
  CONCLUSIONS
  Performing dose recalculation using MVCT of Tomotherapy in head and neck region was feasible.and the dose distributions on kVCT and MVCT were in excellent agreement.
authors.forename: Xiangkun
authors.initials: X
authors.lastname: Dai
authors.forename: Yunlai
authors.initials: Y
authors.lastname: Wang
authors.forename: Linchun
authors.initials: L
authors.lastname: Feng
authors.forename: Wei
authors.initials: W
authors.lastname: Yu
mesh_terms: D000465:Algorithms; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D019047:Phantoms, Imaging; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D036542:Tomography, Spiral Computed / Q000295:instrumentation*