Fetal dose reduction in head and neck radiotherapy of a pregnant woman.
OBJECTIVE
A pregnant woman was referred for post-operative radiotherapy of a malignant schwannoma in the head and neck region. A best-treatment plan was devised in order to minimize the fetal dose.


METHODS
The fetal dose resulting from radiological examinations was determined according to international protocols, that resulting from radiotherapy was calculated according to Recommendation 36 of the American Association of Physicists in Medicine (AAPM) Task Group. Pre-treatment dosimetry was performed with an anthropomorphic phantom. Several alternative treatment plans were evaluated. The use of a multileaf collimator (MLC) and a virtual wedge (VW) was compared to cerrobend blocks (CB) and physical wedge (PW). In-vivo dosimetry was performed using a vaginal probe containing thermoluminescent dosimeters (TLD).


RESULTS
The total fetal dose resulting from diagnostic and radiotherapy procedures was estimated to be 36 mGy. The technique based on MLC and VW was elected for patient treatment. Measurements for this configuration resulted in afetal dose reduction of 82%. The shielding of the patient's abdomen further reduced the fetal dose by 42%.


CONCLUSIONS
The use of VW and MLC for the treatment of a pregnant woman is highly recommended. Each case should be individually studied with pre-treatment and in-vivo dosimetry.
Moeckli
Raphaël
R
University Institute of Applied Radiophysics, Grand-Pré 1, 1007 Lausanne, Switzerland. Raphael.moeckli@inst.hospvd.ch
Ozsahin
Mahmut
M
Pache
Gilbert
G
Valley
Jean-François
JF
Mirimanoff
René-Olivier
RO
Azria
David
D
D000328:Adult; D005260:Female; D005333:Fetus / Q000528:radiation effects*; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed