Room: ePoster Forums
Purpose: To estimate liver doses for a PENTEC (The Pediatric Normal Tissue Effects in the Clinic) study for Wilms tumor patients treated between 1970 and 1999 whose CT images are unavailable. This dose information facilitates the correlation of dose with liver toxicities.
Methods: From the CT scan of the NCI phantom representing a five-year-old pediatric patient, we extracted surface points from the liver contour. These points were scaled and translated to our in-house, age-specific computational phantoms (0.5-15 years). In order to estimate the dose to the liver, flank radiotherapy treatments were simulated on these phantoms using COG Wilms tumor protocol treatment fields. Twelve treatment plans for each age were designed, varying field laterality, nodal involvement, and the superior extent of the radiation field.
Results: For both the left and right flank node positive disease treatments, the mean liver dose decreased as the superior border dropped from T8 to T12 due to the smaller percentage of the organ within the field. The mean liver dose for left flank treatments was significantly lower than that for right flank treatments, reflecting the small portion of the liver that lies to the left of midline. The mean liver dose averaged across all ages for node negative treatments was calculated to be 440 Â± 270 cGy for left flank treatments and 1470 Â± 470 cGy for right flank treatments. The mean liver dose for node positive left flank treatments averaged 660 Â± 160 cGy vs. 2220 Â± 130 cGy for node positive right flank treatments.
Conclusion: Liver dose volume metrics were reconstructed on age specific computational phantoms (age range of children treated for Wilms tumor) for typical flank radiotherapy protocols. The PENTEC GI group will use these data to establish correlations between liver doses and liver toxicities.