Premium
Technical Note: Using virtual noncontrast images from dual‐energy CT to eliminate the need of precontrast CT for x‐ray radiation treatment planning of abdominal tumors †
Author(s) -
Noid George,
Schott Diane,
Paulson Eric,
Zhu Justin,
Shah Jainil,
Li X. Allen
Publication year - 2021
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.14702
Subject(s) - medicine , nuclear medicine , bolus (digestion) , medical imaging , radiation treatment planning , radiation therapy , radiology , surgery
Purpose Radiation therapy (RT) planning frequently utilizes contrast‐enhanced CT. However, dose calculations should not be performed on a contrast‐enhanced CT because the patient will not receive bolus during treatment. It is typical to acquire CT twice during RT simulation: once before injection of bolus and once after. The registration between these datasets introduces errors. In this work, we investigate the use of virtual noncontrast images (VNC) derived from dual‐energy CT (DECT) to eliminate the precontrast CT and the registration error. Methods CT datasets, including conventional 120 kVp pre‐ and postcontrast CTs and postcontrast DECT, acquired for ten pancreatic cancer patients were evaluated. The DECTs were acquired simultaneously using a dual source (DS) CT simulator. VNC and virtual mono‐energetic images (VMI) were derived from DECTs. Gross tumor volumes (GTV), planning target volumes (PTV), and organs at risks (OAR) were delineated on the postcontrast CT and then populated to the precontrast CT and the VNC. An IMRT plan (50.4 Gy in 28 fractions) was then optimized on the precontrast CT. Dose distributions were recalculated on the VNC images. Contours from the pre‐ and postcontrast CTs and the dose distributions based on both were compared. Results On average, the distance of centroids of the populated duodenum contours on precontrast CT differed by 6.0 ± 4.0 mm from those on postcontrast CTs. The dose distributions on the precontrast CT and VNC were almost identical. The PTV mean and maximum doses differed by 0.1% and 0.2% between the two plans, respectively. Conclusion The VNC derived from DECT can be used to replace the conventional precontrast CT scan for RT planning, eliminating the need for an additional precontrast CT scan and eliminating the registration errors. Thus, VNC can become an important asset to the future of RT.