AbstractID: 8170 Title: Fetal Dose During Radiosurgery Treatments of Brain Tumors
The Linac based radiosurgey procedure delivers a high conformal dose via small size
cones with multiple arced radiation beams to tumors and AVM targets treated in cranial
region. The sizes of treated targets range from 1 to 4 cm. In this study, we have
investigated the dose in the pelvic area simulating a pregnant patient. A head phantom
was placed in a stereotactic localization ring and a CT scan was obtained for treatment
planning. The Radionics Xknife treatment planning was used to create several targets
with various sizes and variety of beam arrangements to study the effect of the dose in
pelvis. The head phantom fixed within the ring attachment was placed into the treatment
position. A body phantom was then coupled to the head phantom. The detector was
placed in the pelvis. A plan containing multiple arced beams was delivered to assess the
dose to the pelvic region. The dose due to scatter to the pelvic area was negligible when
the path of the arced beam did not directly intersect the detector. The maximum dose
measured for a sagital beam was less than 0.2 % of the prescribed dose. Avoiding the
pelvic area enveloping the fetus position would limit the treatment planning parameters
very little. Therefore it is evident that developing a treatment plan that both optimizes
tumor volume coverage and minimizes the risk to the fetus is easily obtainable.