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Dose Reduction For The Thin Twin Axial Scan Mode

IP.com Disclosure Number: IPCOM000012541D
Publication Date: 2003-May-13
Document File: 2 page(s) / 409K

Publishing Venue

The IP.com Prior Art Database

Abstract

We have developed the thin twin (TT) mode for multi-slice CT scanners to provide ultra-thin slice/ultra-high resolution images. This is accomplished by limiting the X-ray into the two innermost detector rows using source-collimation. due to the mechanical limitation of the collimators and the artifact level constrain, the collimation could not be set to the theoretical limit. Therefore, a small amount of X-rays are illuminating the adjacent outer detector rows on both sides of the two innermost rows. The current design ignores the information from these two outer detector rows.

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FIELD OF TECHNOLOGY:

Computed Tomography (CT)

TITLE:

Dose Reduction For The Thin Twin Axial Scan Mode

Introduction:

For inner ear canal (IAC) and other high resolution/contrast studies, we have developed the thin twin (TT) mode for multi-slice CT scanners to provide ultra-thin slice/ultra-high resolution images. This is accomplished by limiting the X-ray into the two innermost detector rows using source-collimation.� The TT mode has very high geometric dose efficiency (over 90%) by getting rid of the penumbras that are normally associated with multi-slice CT scanners.� Ideally, we would like to limit all X-rays into the two innermost detector rows.� However, due to the mechanical limitation of the collimators and the artifact level constrain, the collimation could not be set to the theoretical limit.� Therefore, a small amount of X-rays are illuminating the adjacent outer detector rows on both sides of the two innermost rows.� The current design ignores the information from these two outer detector rows.

Disclosure:

In this invention disclosure, we describe a method for the TT axial scan mode to utilize the information from these two outer detector rows in order to reduce the images noise (dose) while maintaining/improving the high contrast resolution.� This method follows the steps of image reconstruction, segmentation and image combination.

(1)   Images from all four detector rows (2a, 1a, 1b and 2b) will be reconstructed.� Because the outer detector rows only received small amount of X-rays compared to the two inner detector rows, the images from these two outer rows are subject to smoothing operation by using the “Signal and Task-dependent Artifact Reduction (STAR)” technique that we have proposed.

(2)   After the reconstruction, images from the four rows are segmented into soft tissue Ist, soft bone Isb and hard bone Ihb regions by using different thresholds Tsb and Thb.

(3)   Images from the A-side (2a, 1a) and B-side (1b, 2b) will then be combined separately using the following a...