Feasibility of using post-contrast dual-energy CT for pediatric radiation treatment planning and dose calculation. Br J Radiol 2021 Feb 01;94(1118):20200170
Date
11/18/2020Pubmed ID
33201728Pubmed Central ID
PMC7934321DOI
10.1259/bjr.20200170Scopus ID
2-s2.0-85100360310 (requires institutional sign-in at Scopus site) 9 CitationsAbstract
OBJECTIVES: When iodinated contrast is administered during CT simulation, standard practice requires a separate non-contrast CT for dose calculation. The objective of this study is to validate our hypothesis that since iodine affects Hounsfield units (HUs) more than electron density (ED), the information from post-contrast dual-layer CT (DLCT) would be sufficient for accurate dose calculation for both photon and proton therapy.
METHODS AND MATERIALS: 10 pediatric patients with abdominal tumors underwent DLCT scans before and after iodinated contrast administration for radiotherapy planning. Dose distributions with these DLCT-based methods were compared to those with conventional calibration-curve methods that map HU images to ED and stopping-power ratio (SPR) images.
RESULTS: For photon plans, conventional and DLCT approaches based on post-contrast scans underestimated the PTV D99 by 0.87 ± 0.70% (p = 0.18) and 0.36 ± 0.31% (p = 0.34), respectively, comparing to their non-contrast optimization plans. Renal iodine concentration was weakly associated with D99 deviation for both conventional (R2 = 0.10) and DLCT (R2 = 0.02) approaches. For proton plans, the clinical target volume D99 errors were 3.67 ± 2.43% (p = 0.0001) and 0.30 ± 0.25% (p = 0.40) for conventional and DLCT approaches, respectively. The proton beam range changed noticeably with the conventional approach. Renal iodine concentration was highly associated with D99 deviation for the conventional approach (R2 = 0.83) but not for DLCT (R2 = 0.007).
CONCLUSION: Conventional CT with iodine contrast resulted in a large dosimetric error for proton therapy, compared to true non-contrast plans, but the error was less for photon therapy. These errors can be greatly reduced in the case of the proton plans if DLCT is used, raising the possibility of using only a single post-contrast CT for radiotherapy dose calculation, thus reducing the time and imaging dose required.
ADVANCES IN KNOWLEDGE: This study is the first to compare directly the differences in the calculated dose distributions between pre- and post-contrast CT images generated by single-energy CT and dual-energy CT methods for photon and proton therapy.
Author List
Ates O, Hua CH, Zhao L, Shapira N, Yagil Y, Merchant TE, Krasin MAuthor
Li Zhao PhD Associate Professor in the Radiation Oncology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Abdominal NeoplasmsAdolescent
Adult
Child
Child, Preschool
Contrast Media
Feasibility Studies
Female
Humans
Iodine
Male
Proton Therapy
Radiographic Image Enhancement
Radiography, Dual-Energy Scanned Projection
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Tomography, X-Ray Computed
Young Adult
