Phantom Study on Dose Reduction Using Iterative Reconstruction in Low-dose Computed Tomography for Lung Cancer Screening

Abstract

We investigated dose reduction ability of an iterative reconstruction technology for low-dose computed tomography (CT) for lung cancer screening. The Sinogram Affirmed Iterative Reconstruction (SAFIRE) provided in a multi slice CT system, Somatom Definition Flash (Siemens Healthcare) was used. An anthropomorphic chest phantom (N-1, Kyoto Kagaku) was scanned at volume CT dose index (CTDIvol) of 0.50-11.86 mGy with 120 kV. For noise (standard deviation) and contrast-to-noise ratio (CNR) measurements, CTP486 and CTP515 modules in the Catphan (The Phantom Laboratory) were scanned. Radiological technologists were participated in the perceptual comparison. SAFIRE reduced the SD values by approximately 50% compared with filter back projection (FBP). The estimated dose reduction rates by SAFIRE determined from the perceptual comparison was approximately 23%, while 75% dose reduction rate was expected from the SD value reduction of 50%.

Screening for lung cancer using sub-millisievert chest CT with iterative reconstruction algorithm: image quality and nodule detectability

“…In addition, it is worth to note that the LDCT protocol combined with iDose 4 was practiced as reference standard instead of fulldose protocol with FBP reconstruction in our study, considering iDose 4 , the hybrid IR, has already been used routinely with robust reconstruction speed, as well as the hybrid IRs such as iDose 4 , sinogram-affirmed iterative reconstruction, and adaptive statistical iterative reconstruction were observed yielding diagnostic image quality in LD chest CT with similar dose setting at around 1 mSv. 13,17,18 Our study has several limitations. First, a relatively small number of positive cases were reviewed in the study.…”

Effect of Radiation Dose Reduction and Reconstruction Algorithm on Image Noise, Contrast, Resolution, and Detectability of Subtle Hypoattenuating Liver Lesions at Multidetector CT: Filtered Back Projection versus a Commercial Model–based Iterative Reconstruction Algorithm

“…For example, the clinical studies have typically been based on subjective visual scoring of quality (7,21,22,24,26) and the phantom studies have been based on the measurement of physical image characteristics such as noise and/or resolution (1,6,13,15). Under the formalism established by International Commission on Radiation Units and Measurements report 54 (27), image quality is defined as the effectiveness by which an image can be used for its intended task.…”

Low-Dose CT for Lung Cancer Screening

“…Several studies have demonstrated that IR techniques help improve image quality and retain diagnostic value of LDCT at substantially reduced radiation dose [6][7][8].…”