Tumor characterization and image quality

Radiation oncologists are eager to characterize tumor and noninvolved normal tissues to delineate target volume and avoid toxicity. The advent of highly conformal radiation therapy, the feasibility of dose painting, and the realization of pencil-beam scanning proton therapy have provided new treatment-planning challenges and opportunities to differentially irradiate high-risk tumor subvolumes when reliably identified. DECT has been used to accurately differentiate and characterize normal tissues for radiotherapy applications, including treatment planning of radiation therapy,21-23 identifying subvolumes within the gross tumor volume for dose paintin,24 and reducing metal artifact for more accurate tumor delineation in dental regions, spine, and hips.25,26 In the preclinical setting, DECT has been used to evaluate bone marrow edema attributed to radiation-induced damage.27 The concept of tumor characterization is highlighted in Figures 2-4.

(2) demonstrating the extent of the panels include conventional CT, monoenergetic 40 keV, iodine-density, and Z effective images. (3) Contrast-enhanced sagittal CT images of pediatric low-grade glioma demonstrating the extent of the tumor in the optic pathway. Left → right, panels include conventional CT, monoenergetic 40 keV, iodine-density, and Z effective images. (4) Contrast-enhanced axial CT images of pediatric Ewing sarcoma demonstrating the extent of the tumor in the bone and soft tissue. Left → right, panels comparing pre- vs. post-chemotherapy monoenergetic 40 keV images and pre- vs. post-chemotherapy Z effective images.