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Radiother Oncol. 2015 Apr;115(1):22-9. doi: 10.1016/j.radonc.2015.02.022. Epub 2015 Mar 26.

Preliminary clinical evaluation of a 4D-CBCT estimation technique using prior information and limited-angle projections.

Author information

1
Medical Physics Graduate Program, Duke University, Durham, USA. Electronic address: you.zhang@duke.edu.
2
Medical Physics Graduate Program, Duke University, Durham, USA; Department of Radiation Oncology, Duke University Medical Center, Durham, USA.
3
Department of Imaging Physics, The University of Texas, MD Anderson Cancer Center, Houston, USA.
4
Department of Radiation Oncology, Duke University Medical Center, Durham, USA.

Abstract

BACKGROUND AND PURPOSE:

A technique has been previously reported to estimate high-quality 4D-CBCT using prior information and limited-angle projections. This study is to investigate its clinical feasibility through both phantom and patient studies.

MATERIALS AND METHODS:

The new technique used to estimate 4D-CBCT is called MMFD-NCC. It is based on the previously reported motion modeling and free-form deformation (MMFD) method, with the introduction of normalized-cross-correlation (NCC) as a new similarity metric. The clinical feasibility of this technique was evaluated by assessing the accuracy of estimated anatomical structures in comparison to those in the 'ground-truth' reference 4D-CBCTs, using data obtained from a physical phantom and three lung cancer patients. Both volume percentage error (VPE) and center-of-mass error (COME) of the estimated tumor volume were used as the evaluation metrics.

RESULTS:

The average VPE/COME of the tumor in the prior image was 257.1%/10.1 mm for the phantom study and 55.6%/3.8 mm for the patient study. Using only orthogonal-view 30° projections, the MMFD-NCC has reduced the corresponding values to 7.7%/1.2 mm and 9.6%/1.1 mm, respectively.

CONCLUSION:

The MMFD-NCC technique is able to estimate 4D-CBCT images with geometrical accuracy of the tumor within 10% VPE and 2 mm COME, which can be used to improve the localization accuracy of radiotherapy.

KEYWORDS:

4D-CBCT; Free-form deformation; Image estimation; Motion modeling

PMID:
25818396
PMCID:
PMC4464962
DOI:
10.1016/j.radonc.2015.02.022
[Indexed for MEDLINE]
Free PMC Article

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