title: A modified 60C teletherapy unit for total body irradiation.
abstract: OBJECTIVE
  A modified teletherapy unit to achieve total body irradiation with a vertical beam in a conventional treatment room.
  
  
  METHODS
  A standard 60C teletherapy unit has been modified to achieve total body irradiation with a vertical beam in a conventional treatment room. Patients are treated in prone and supine positions. Removal of the adjustable collimator assembly of this standard machine provides a circular field of 196 cm in diameter at 167 cm from the source. Second, the machine has been elevated by about 50 cm on a metallic base to enlarge irradiation field to obtain 248 cm in diameter at 210 cm from the source, and to encompass tall patients under better conditions. A special lead conical beam flattening filter, 10-mm thick at the center, was designed to compensate the spatial inhomogeneity of the beam. An instantaneous dose rate of 6.10(-2) Gy/min is attained at the L4 level (midplane) in an average 20-cm thick patient with a source activity of 5099 RHM (air kerma rate of 44.8 Gy.h-1.m2). Between February 2, 1984 and December 27, 1990, 244 total body irradiations were performed either by single dose (n = 69, 10 Gy were given to midplane at L4 level in about 6 to 8 h, 8 Gy to the lungs), or by fractionated dose (n = 175, 12 Gy were given in 6 fractions over 3 consecutive days to midplane at L4 level, 9 Gy to the lungs).
  
  
  RESULTS
  The dose distribution is similar than the ones obtained by a linear accelerator with patients lying on their sides.
  
  
  CONCLUSIONS
  Patients were treated in a comfortable and highly reproductible position. Organ shielding was easily achievable. This could be a less expensive and reasonable alternative to linear accelerator.
authors.affiliation: Department of Radiation Oncology, Hôpital Tenon, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Dominique
authors.forename: L H
authors.initials: LH
authors.lastname: Schwartz
authors.forename: J
authors.initials: J
authors.lastname: Lescrainier
authors.forename: K
authors.initials: K
authors.lastname: Keraudy
authors.forename: Y
authors.initials: Y
authors.lastname: Belkacemi
authors.forename: J N
authors.initials: JN
authors.lastname: Foulquier
authors.forename: M
authors.initials: M
authors.lastname: Ozsahin
authors.forename: D
authors.initials: D
authors.lastname: Lefkopoulos
authors.forename: F
authors.initials: F
authors.lastname: Pene
mesh_terms: D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D004867:Equipment Design; D006801:Humans; D011835:Radiation Protection; D011867:Radioisotope Teletherapy / Q000295:instrumentation* / Q000379:methods; D014916:Whole-Body Irradiation / Q000295:instrumentation* / Q000379:methods
chemical_list: D003037:Cobalt Radioisotopes