PURPOSE: To develop an imaging method to characterize and map marrow composition in the entire skeletal system, and to simulate differential targeted marrow irradiation based on marrow composition.
METHODS AND MATERIALS: Whole-body dual energy computed tomography (DECT) images of cadavers and leukemia patients were acquired, segmented to separate bone marrow components, namely, bone, red marrow (RM), and yellow marrow (YM). DECT-derived marrow fat fraction was validated using histology of lumbar vertebrae obtained from cadavers. The fractions of RM (RMF = RM/total marrow) and YMF were calculated in each skeletal region to assess the correlation of marrow composition with sites and ages. Treatment planning was simulated to target irradiation differentially at a higher dose (18 Gy) to either RM or YM and a lower dose (12 Gy) to the rest of the skeleton.
RESULTS: A significant correlation between fat fractions obtained from DECT and cadaver histology samples was observed (r=0.861, P<.0001, Pearson). The RMF decreased in the head, neck, and chest was significantly inversely correlated with age but did not show any significant age-related changes in the abdomen and pelvis regions. Conformity of radiation to targets (RM, YM) was significantly dependent on skeletal sites. The radiation exposure was significantly reduced (P<.05, t test) to organs at risk (OARs) in RM and YM irradiation compared with standard total marrow irradiation (TMI).
CONCLUSIONS: Whole-body DECT offers a new imaging technique to visualize and measure skeletal-wide marrow composition. The DECT-based treatment planning offers volumetric and site-specific precise radiation dosimetry of RM and YM, which varies with aging. Our proposed method could be used as a functional compartment of TMI for further targeted radiation to specific bone marrow environment, dose escalation, reduction of doses to OARs, or a combination of these factors.
|Number of pages||9|
|Journal||International Journal of Radiation Oncology, Biology, Physics|
|Publication status||Published - 1 Nov 2016|
Bibliographical noteCopyright © 2016 Elsevier Inc. All rights reserved.
- Bone Marrow/diagnostic imaging
- Dose-Response Relationship, Radiation
- Leukemia/diagnostic imaging
- Middle Aged
- Radiography, Dual-Energy Scanned Projection/methods
- Radiotherapy Dosage
- Radiotherapy, Image-Guided/methods
- Reproducibility of Results
- Sensitivity and Specificity
- Tomography, X-Ray Computed/methods
- Whole Body Imaging/methods
- Whole-Body Irradiation/methods