title: [A special radiation shielding for the radiotherapy of a pregnant patient].
abstract: OBJECTIVE
  Measurement of the radiation dose of different radiotherapy techniques with a phantom at the position of the uterus of a pregnant patient with and without a special radiation shielding.
  
  
  METHODS
  A special radiation shielding for the radiation therapy of a pregnant patient was constructed in the shape of a tunnel over the abdomen from 1 cm thick lead to reduce scatter radiation to the uterus and the fetus therein. The reduction of the scatter radiation to the lower abdomen was measured for three typical cases (cerebrum with lateral opposed fields, 6-MV photons; tangential fields for mamma irradiation, 6 MV; and anteroposterior-posteroanterior [AP-PA] opposed fields of 15 MV for treatment of the mediastinum) at an anthropomorphic Alderson phantom with thermoluminescence dosimeters in different depths and with an ionization chamber positioned in an RW3 solid water phantom. In the case of lateral opposed fields, a movable lead wall was additionally positioned next to the accelerator's head to reduce the scatter radiation from this source.
  
  
  RESULTS
  Depending on the geometry of the radiation fields and on the photon energy, a reduction of the dose to the lower abdomen averaged over the depths of 6, 9, and 12 cm from 16% (15 MV, mediastinum case) to 51% (6 MV, cerebrum with additional lead wall) was achieved. The absolute scattered dose with shielding in place for a 2-Gy fraction dose results to 3.85 mGy and 0.27 mGy, respectively.
  
  
  CONCLUSIONS
  National and international recommendations on the radiation dose to a fetus of a pregnant patient state limits of 200 mSv (DGMP report no. 7) and 100 mGy (ICRP 84), below which an abortion should not be considered and above which an indication for termination of the pregnancy could be given, respectively. The dose to the fetus can be kept below these limits with the shielding described in this work. Therefore, a radiation therapy of a pregnant patient is possible when these special precautions to reduce the scatter radiation to the fetus are met.
authors.affiliation: Bereich Medizinische Physik, Universitätsklinik für Radioonkologie, Tübingen, Deutschland. Markus.Buchgeister@med.uni-tuebingen.de
authors.forename: Markus
authors.initials: M
authors.lastname: Buchgeister
authors.forename: Andre
authors.initials: A
authors.lastname: Mondry
authors.forename: Patrick
authors.initials: P
authors.lastname: Spillner
authors.forename: Frank
authors.initials: F
authors.lastname: Paulsen
authors.forename: Claus
authors.initials: C
authors.lastname: Belka
authors.forename: Michael
authors.initials: M
authors.lastname: Bamberg
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005315:Fetal Diseases / Q000517:prevention & control*; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000517:prevention & control*; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000517:prevention & control*; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry