Evaluation of fan-beam kilovoltage computed tomography image quality on a novel biological-guided radiotherapy platform

Tingliang Zhuang; Grant Gibbard; Xinhui Duan; Jun Tan; Yang Park; Mu-Han Lin; Zhihui Sun; Oluwaseyi M Oderinde; Weiguo Lu; Robert Reynolds; Andrew Godley; Arnold Pompos; Tu Dan; Aurelie Garant; Puneeth Iyengar; Robert Timmerman; Steve Jiang; Bin Cai

doi:10.1016/j.phro.2023.100438

Evaluation of fan-beam kilovoltage computed tomography image quality on a novel biological-guided radiotherapy platform

Phys Imaging Radiat Oncol. 2023 Apr 10:26:100438. doi: 10.1016/j.phro.2023.100438. eCollection 2023 Apr.

Authors

Tingliang Zhuang¹, Grant Gibbard¹, Xinhui Duan², Jun Tan¹, Yang Park¹, Mu-Han Lin¹, Zhihui Sun³, Oluwaseyi M Oderinde³, Weiguo Lu¹, Robert Reynolds¹, Andrew Godley¹, Arnold Pompos¹, Tu Dan¹, Aurelie Garant¹, Puneeth Iyengar¹, Robert Timmerman¹, Steve Jiang¹, Bin Cai¹

Affiliations

¹ Department of Radiation Oncology, University of Texas- Southwestern Medical Center, Dallas, USA.
² Department of Radiology, University of Texas- Southwestern Medical Center, Dallas, USA.
³ RefleXion Medical, Inc, Hayward, CA, USA.

Abstract

Background and purpose: A recently developed biology-guided radiotherapy platform, equipped with positron emission tomography (PET) and computed tomography (CT), provides both anatomical and functional image guidance for radiotherapy. This study aimed to characterize performance of the kilovoltage CT (kVCT) system on this platform using standard quality metrics measured on phantom and patient images, using CT simulator images as reference.

Materials and methods: Image quality metrics, including spatial resolution/modular transfer function (MTF), slice sensitivity profile (SSP), noise performance and image uniformity, contrast-noise ratio (CNR) and low-contrast resolution, geometric accuracy, and CT number (HU) accuracy, were evaluated on phantom images. Patient images were evaluated mainly qualitatively.

Results: On phantom images the MTF_10% is about 0.68 lp/mm for kVCT in PET/CT Linac. The SSP agreed with nominal slice thickness within 0.7 mm. The diameter of the smallest visible target (1% contrast) is about 5 mm using medium dose mode. The image uniformity is within 2.0 HU. The geometric accuracy tests passed within 0.5 mm. Relative to CT simulator images, the noise is generally higher and the CNR is lower in PET/CT Linac kVCT images. The CT number accuracy is comparable between the two systems with maximum deviation from the phantom manufacturer range within 25 HU. On patient images, higher spatial resolution and image noise are observed on PET/CT Linac kVCT images.

Conclusions: Major image quality metrics of the PET/CT Linac kVCT were within vendor-recommended tolerances. Better spatial resolution but higher noise and better/comparable low contrast visibility were observed as compared to a CT simulator when images were acquired with clinical protocols.

Keywords: CT simulator; Image quality; PET/CT Linac; kV fan-beam CT.