Determination of Dose Escalation Region in Malignant Brain tumors for Radiation Treatment Planning Based on Apparent Diffusion Coefficient Map

Abstract

AbstractTreatment effect of malignant brain tumors including astrocytoma and glioma has showed low survival and frequent tumor recurrence. Several clinical study, however, reported that dose escalation with chemotherapy produced better prognosis than conventional radiation therapy. Thus, we investigated feasibility and advantage of integrating apparent diffusion coefficient (ADC) map in treatment planning to determine the dose escalation region.Multimodal image sets of glioma and astrocytoma were acquired with CT, contrast-enhanced T1, fluid attenuated inversion recovery (FLARE), and diffusion weighted (DW) magnetic resonance (MR) images. ADC map was obtained from DW images and it was converted into the ADC ratio divided by the average ADC of normal parenchyma in contralateral brain. ADC ratio was used as quantitative criteria representing tumor malignancy and gross tumor volume (GTV) was differentiated by the level of the ADC ratio. GTV of each mulimodal images and stratified regions by ADC ratio were registered on CT using rigidbody registration.More progreesed tumor region was distinguished in GTV and location of the most malignant tumor in 3D space was also resolved by the ADC ratio. Multimodal images and ADC ratio map were complementary to describe more reliable tumor contour. The advanced radiation treatment planning reflecting biological tumor characteristic was attempted using the ADC map.ADC ratio was useful to stratify the tumor in regard to malignancy and it was suggeted a quantitative criteria to dermine the dose escalation region.Keywordsdose escalationapparent diffusion coefficient maptreatment planningmultimodal imagesmalignant brain tumor