Evaluation of the peripheral dose to uterus in breast carcinoma radiotherapy.
The absorbed dose outside of the direct fields of radiotherapy treatment (or peripheral dose, PD) is responsible for radiation exposure of the fetus in pregnant women. Because the radiological protection of the unborn child is of particular concern in the early period of the pregnancy, the aim of this study is to estimate the PD in order to assess the absorbed dose in the uterus in a pregnant patient irradiated for breast carcinoma therapy. The treatment was simulated on an Alderson-Rando anthropomorphic phantom, and the radiation dose to the fetus was measured using an ionisation chamber and thermoluminescence dosemeters. Two similar treatments plans with and without wedges were delivered, using a 6 MV photon beam with two isocentric opposite tangential fields with a total dose of 50 Gy, in accordance with common established procedures. Average field parameters for more than 300 patients were studied. Measurements showed the fetal dose to be slightly lower than 50 mGy, a level at which the risk to the fetus is uncertain, although several authors consider this value as the dose threshold for deterministic effects. The planning system (PS) underestimated PD values and no significant influence was found with the use of wedge filters.
Martín Rincón
C
C
So de Radiofisíca y protección Radiológica, Hospital U. de la Princesa, Madrid, Spain.
Jerez Sainz
I
I
Modolell Farré
I
I
España López
M L
ML
López Franco
P
P
Muñiz
J L
JL
Romero
A M
AM
Rodríguez
R
R
D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D019047:Phantoms, Imaging; D011247:Pregnancy; D011248:Pregnancy Complications / Q000532:radiotherapy; D011878:Radiotherapy / Q000009:adverse effects* / Q000379:methods; D014057:Tomography, X-Ray Computed; D014599:Uterus / Q000528:radiation effects*