Obviousness

US patent 8265353 addresses the challenge of reconstructing high-quality images of mobile objects, particularly living beings, by combining data from two different imaging techniques while compensating for movement. An analysis under 35 U.S.C. § 103 for obviousness considers whether the claimed invention would have been obvious to a person having ordinary skill in the art (POSITA) at the time of the invention (before October 1, 2003, the priority date).

The independent claims (Claim 1 and Claim 12) describe a method and apparatus, respectively, for forming an image of a mobile object by:

• Obtaining first images using a first imaging technique (e.g., radiation attenuation like CT) and concurrently obtaining first movement measurements from a first independent sensor system.
• Associating these first images with first movement states based on the first measurements.
• Obtaining second images using a second, different imaging technique (e.g., radiation emission like PET/SPECT) and concurrently obtaining second movement measurements from a second independent sensor system.
• Associating these second images with second movement states based on the first measurements.
• Forming a final image by combining the first images, their associated first movement measurements and states, and the second images, their associated second movement measurements and states.

A POSITA in this field (e.g., a medical imaging engineer or physicist) in 2003 would possess knowledge of various imaging modalities, image reconstruction techniques, and methods for addressing motion artifacts.

Prior Art References for Obviousness Analysis:

1. Kinahan et al., "Attenuation correction for a combined 3D PET/CT scanner" (1998): This article describes devices for simultaneously acquiring both attenuation (CT) and emission (PET) images and explicitly discusses using CT data for attenuation correction of PET data. [cite: The Google Patents page for US8265353B2, in its "Prior art" and "Definitions" sections, references Kinahan et al. regarding devices for simultaneously acquiring both types of images, as well as attenuation correction for combined PET/CT scanners.] This reference establishes the concept of dual-modality imaging with data integration between different techniques.
2. US20030004405A1 (CTI PET Systems, Inc.): This patent also describes a "Combined PET and X-Ray CT tomograph." [cite: The Google Patents page for US8265353B2, in its "Patent Citations" section, lists US20030004405A1 as a "Combined PET and X-Ray CT tomograph".]
3. Grangeat et al., "Theoretical framework for a dynamic cone-beam reconstruction algorithm based on a dynamic particle model" (2002): This work, co-authored by one of the inventors of US8265353, details image reconstruction for dynamic objects (i.e., compensating for movement) using an attenuation technique. [cite: The Google Patents page for US8265353B2, in its "Description" section, refers to Grangeat et al. for the "previous state of the art" concerning attenuation techniques.]
4. Gilland et al., "Simultaneous reconstruction and motion estimation for gated Cardiac ECT" (2002): This article addresses motion estimation and image reconstruction for an emission technique, specifically using gating for cardiac ECT. [cite: The Google Patents page for US8265353B2, in its "Description" section, refers to Gilland et al. for the "previous state of the art" concerning emission techniques.]
5. French patent 2 826 157 and FR 2736454: These patents describe general methods for digital correction of images by estimating displacement fields to account for object movements. [cite: The Google Patents page for US8265353B2, in its "Definitions" section, refers to French patent 2 826 157 as an example of methods involving digital correction of measurements and images, considering object displacements.]
6. General knowledge regarding independent physiological sensors (e.g., breathing sensors, ECG) for motion gating: The patent itself acknowledges this as a "useful method," stating, "One useful method for achieving this may be to measure a patient movement using an independent sensor such as a breathing sensor, a pressure sensor or an electrocardiogram." [cite: The Google Patents page for US8265353B2, in its "Definitions" section, describes measuring patient movement with independent sensors and associating measurement sets with determined patient states.] This practice was well-known in medical imaging for synchronizing acquisitions with physiological cycles. Kachelriess et al. (2002) is also cited for time synchronization in cardiac CT, which often involves such sensors. [cite: The Google Patents page for US8265353B2, in its "Description" section, cites Kachelriess et al. as an example of time synchronization by correlation processes between image projections.]

Obviousness Combination and Motivation:

A POSITA would have been motivated to combine these prior art references to overcome the known limitations of emission imaging, particularly its susceptibility to motion artifacts and lower spatial resolution compared to attenuation imaging.

1. Known Problem: Emission images (PET/SPECT) inherently suffer from poorer spatial resolution and are more prone to blurring from patient movement due to longer acquisition times. The patent explicitly states that it is "difficult to establish a displacement field" for emission images because their "measurements are more dispersed in time and they are not as easily recognizable" for different tissue categories compared to attenuation images. [cite: The Google Patents page for US8265353B2, in its "Definitions" section, highlights these difficulties for emission images.]
2. Known Solutions:
   • Dual-modality acquisition: Kinahan et al. (1998) and US20030004405A1 already teach the simultaneous acquisition of data from both attenuation (CT) and emission (PET) techniques. [cite: The Google Patents page for US8265353B2, in its "Prior art" and "Patent Citations" sections, cites Kinahan et al. and US20030004405A1 respectively for combined PET/CT systems.]
   • Motion estimation and compensation for individual modalities: Grangeat et al. (2002) and Gilland et al. (2002) demonstrated established methods for estimating and compensating for motion in attenuation and emission imaging, respectively. [cite: The Google Patents page for US8265353B2, in its "Description" section, mentions Grangeat et al. for attenuation techniques and Gilland et al. for emission techniques as "previous state of the art".] French patents 2 826 157 and FR 2736454 further reinforced the general concept of displacement field estimation for image correction. [cite: The Google Patents page for US8265353B2, in its "Definitions" section, references French patent 2 826 157.]
   • Physiological gating with independent sensors: The use of external sensors (e.g., breathing sensors, ECG) to measure patient movement and synchronize image acquisitions to specific movement states (gating) was a "useful method" and part of the general knowledge in the field, as acknowledged in the patent itself and exemplified by Kachelriess et al. (2002) for cardiac imaging. [cite: The Google Patents page for US8265353B2, in its "Definitions" and "Description" sections, confirms this general knowledge and cites Kachelriess et al.]

The motivation for a POSITA to combine these known elements would be straightforward: to improve the accuracy and sharpness of motion-sensitive emission images by leveraging the more robust and precise motion information available from simultaneously acquired attenuation images. Given that Kinahan et al. already taught using CT data for attenuation correction of PET data, it would be an obvious extension to use the CT data for motion correction as well, particularly since the patent itself states that displacement fields from attenuation techniques are "usually much more precise and accurate" than those from emission techniques. [cite: The Google Patents page for US8265353B2, in its "Definitions" section, explicitly makes this comparison.]

Therefore, a POSITA, seeking to enhance emission image quality by mitigating motion artifacts, would find it obvious to:

1. Acquire both attenuation and emission images using a combined system (Kinahan et al., US20030004405A1).
2. Use independent sensors to measure patient movement and associate corresponding image sets from both modalities with specific movement states (general knowledge, Kachelriess et al.).
3. Estimate displacement fields for movement compensation from both modalities (Grangeat et al., Gilland et al., FR 2826157), recognizing the superior quality of the displacement fields derived from the attenuation data.
4. Combine these elements by using the more reliable motion information from the attenuation technique to inform and enhance the reconstruction of the emission images, thereby producing a sharper and more accurate final image, particularly for the emission component.

The specific phrasing in Claim 1 regarding the use of "first measurements" (from the first sensor system) to associate both first and second images with movement states represents a design choice for a shared or primary motion reference, which would be an obvious implementation given the known methods of synchronizing different data streams.

In conclusion, the combination of Kinahan et al. (for dual-modality acquisition and data integration), Grangeat et al. and Gilland et al. (for modality-specific motion estimation), French patents 2 826 157 and FR 2736454 (for general motion correction), and the well-known practice of using independent physiological sensors for gating in medical imaging, would render the claims of US8265353 obvious to a person of ordinary skill in the art with a clear motivation to improve motion-corrupted emission images.