IP Law Daily, PATENT—Fed. Cir.: Three X-ray imaging claims invalidated; three remanded for reconsideration of validity, (May 27, 2025)

By Saurabh Kashyap, B.A., LL.B., LL.M.

PTAB narrowly construed projection magnification limitation in patent claims, misapplied inherent anticipation, and failed to assess obviousness under proper construction.

The U.S. Court of Appeals for the Federal Circuit has reversed in part, vacated in part, and remanded the Patent Trial and Appeal Board’s decision in an inter partes review (IPR), which upheld the validity of multiple claims of Carl Zeiss X-Ray Microscopy, Inc.’s U.S. Patent No. 7,400,704 (the ’704 patent) covering X-ray imaging systems. The Board’s finding that claims 1, 3, and 4 were not anticipated was reversed because it applied an unduly narrow construction of the projection magnification limitation in the claim language, overlooking inherent disclosure in the prior art; the Board’s decision as to claims 2, 5, and 6 was vacated and remanded because it had not evaluated obviousness under the correct construction (Sigray, Inc. v. Carl Zeiss X-Ray Microscopy, Inc., No. 23-2211 (Fed. Cir. May 23, 2025)).

Background. The appellant, Sigray, Inc., is a California-based manufacturer of advanced X-ray and spectroscopy imaging systems for research and industrial use. The appellee, Carl Zeiss X-Ray Microscopy, Inc., produces high-resolution 3D X-ray imaging instruments widely used in scientific and materials research.

Sigray challenged several claims of the ’704 patent in an IPR proceeding, alleging invalidity on the grounds of anticipation and obviousness based on published prior art. The ’704 patent covers a multi-stage X-ray imaging system that uses both projection (or geometric) magnification and optical magnification to generate enhanced-resolution images. The system combines a diverging X-ray beam with a scintillator, magnification lens, and detector, with specified magnification thresholds at both stages.

Sigray’s IPR petition focused on a 1998 academic paper by Jorgensen et al., which described X-ray micro-computed tomography (micro-CT) techniques used for imaging rodent organs. Sigray argued that although the Jorgensen paper did not explicitly use the term “projection magnification,” its described system necessarily produced geometric magnification within the claimed range due to its use of diverging rays and specific component spacing. The PTAB was not persuaded by this argument and upheld the claims, ruling that the prior art did not disclose the required magnification and that Sigray failed to prove unpatentability. Sigray appealed.

Claim construction error. On appeal, the Federal Circuit held that the PTAB had incorrectly construed the phrase “between 1 and 10 times” by implying a threshold below which magnification would not count. Although the Board disclaimed any formal claim construction, the appellate court found that its repeated focus on whether the divergence was “enough” or “meaningful” revealed an improper narrowing of the claim scope. The appellate court explained that the plain language of the claims covered any magnification greater than one, no matter how small.

The court cited Google LLC v. EcoFactor, Inc., 92 F.4th 1049 (Fed. Cir. 2024) to reinforce the principle that claim construction can occur implicitly and that any interpretation limiting the ordinary scope of a term must be supported by intrinsic evidence. Here, there was none. The Board's reliance on language minimizing the extent of divergence or magnification showed that it had effectively excluded minor inherent magnification from the claim—contrary to its plain wording.

Inherent anticipation. The appellate court determined that the Jorgensen reference inherently disclosed the projection magnification range specified in the claims. Drawing on SmithKline Beecham Corp. v. Apotex Corp., 403 F.3d 1331 (Fed. Cir. 2005), the court emphasized that a feature is inherently disclosed if it is necessarily present in the operation of a prior art system—even if not recognized or intended at the time.

Expert testimony submitted by Zeiss acknowledged that perfect collimation of X-rays is physically unattainable and that some level of beam divergence—and thus magnification—is always present. The Federal Circuit concluded that the system described in Jorgensen, despite aiming to minimize magnification, necessarily included nonzero geometric magnification falling within the claimed range.

Application of legal standards. The Federal Circuit noted that anticipation is a factual question, but when the Board applies an incorrect legal standard—as it did here in construing the claim—appellate review is de novo. The court emphasized that a correct understanding of the claim scope was dispositive, as the evidence conclusively showed that Jorgensen's system produced magnification within the literal bounds of the claims. Applying Owens Corning v. Fast Felt Corp., 873 F.3d 896 (Fed. Cir. 2017), the court found that reversal—not remand—was appropriate for the claims at issue because only one finding was supported by the record.

Claims 1, 3, and 4 invalidated. Furthermore, the Federal Circuit reversed the PTAB's determination concerning claims 1, 3, and 4, holding them anticipated by the prior art. These dependent claims incorporated limitations from claim 1 and were not separately defended by Zeiss on appeal or before the Board. The court noted that dependent claims, which are not independently argued, typically rise or fall with the independent claim, citing Soverain Software LLC v. Newegg Inc., 728 F.3d 1332 (Fed. Cir. 2013).

Remand on obviousness. For claims 2, 5, and 6, which had been challenged only on grounds of obviousness, the court vacated the PTAB's findings and remanded for reconsideration under the correct claim interpretation. The court reaffirmed that anticipation and obviousness are distinct inquiries, citing Cohesive Technologies, Inc. v. Waters Corp., 543 F.3d 1351 (Fed. Cir. 2008) and that a finding of inherent anticipation does not automatically dictate the outcome of an obviousness analysis.

The case is No. 23-2211.

Judge: Goldberg, M.

Attorneys: Alan Grayson Laquer (Olson & Bear, LLP) for Sigray, Inc. Kurt Louis Glitzenstein (Fish & Richardson P.C.) for Carl Zeiss X-Ray Microscopy, Inc.

Companies: Sigray, Inc.; Carl Zeiss X-Ray Microscopy, Inc.

Cases: Patent FedCirNews