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Evaluation of a Z Resolution Enhancement Method (Fine Z) in CT

B Nett*, A Hagiwara, K Mcclure. GE Healthcare

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: To quantify the impact of a z resolution enhancement reconstruction technique in axial CT image reconstruction on standard reconstruction metrics.

Methods: The Fine Z image reconstruction option (GE Healthcare, Waukesha WI) enables enhancement of the Z resolution through a combination of adaptive z detail enhancement in the projection and the image space. It takes advantage of the rich data available when there is overlap in the image space, i.e. 0.625mm thickness with a 0.3125mm interval. In the same manner that reconstruction kernels have been used for years to improve in-plane spatial resolution, the Fine Z option enables enhanced z resolution with the associated trade-off of increased image noise.

The z resolution was assessed on the Revolution CT with the standard sloped wire methodology where in-plane measurements of the length of a sloped wire (slope 4:1) are used to assess z axis spatial resolution. Data was acquired for 4 z locations to cover the complete 160mm z extent, reconstructed with the bone plus kernel with 14mm DFOV. Noise was assessed with measurements from a 20cm water phantom, reconstructed with bone plus kernel 25cm DFOV.

Results: The average improvement in ratio [FineZ/Orig] for the zMTF was: 1.35 (50% MTF) and 1.30 (10% MTF). The std dev of the image noise increased by a ratio of 1.22 [FineZ/Orig].

Conclusion: This work indicates the potential for image kernel like behavior in the z direction. This may be beneficial for high resolution tasks where there is a desire to increase the image sharpness in the z direction.

Download ePoster [PDF]

Funding Support, Disclosures, and Conflict of Interest: The authors are employees of GE Healthcare.

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