Elekta Inc. v. Varian Medical Systems, Inc.

1. Case Identification

• Case #: IPR2016-00547
• Patent #: 7,945,021
• Filed: February 2, 2016
• Petitioner(s): Elekta Inc.
• Patent Owner(s): Varian Medical Systems, Inc.
• Challenged Claims: 57-59

2. Patent Overview

• Title: Patient Imaging System
• Brief Description: The ’021 patent discloses a clinical radiation treatment system, such as a linear accelerator, integrated with an imaging system. The invention uses a cone-beam radiation source and a flat-panel imager mounted on a rotatable gantry to acquire cone-beam computed tomography (CT) image data, which can be used to generate 3D images for positioning a patient and modifying radiation treatment plans.

3. Grounds for Unpatentability

Ground 1: Anticipation over Jaffray MICCAI 2001 - Claims 57-59 are anticipated by Jaffray MICCAI 2001 under §102.

• Prior Art Relied Upon: Jaffray MICCAI 2001 (an October 2001 article titled "Image Guided Radiotherapy of the Prostate").
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Jaffray MICCAI 2001 discloses every limitation of the challenged claims. The reference describes a prototype system integrating a cone-beam CT imager onto an Elekta SL20 linear accelerator. This system inherently includes a frame, a rotatable gantry, a high-energy therapeutic source, a separate kilovoltage cone-beam source, and a flat-panel imager, as recited in base claim 53. For dependent claims 57-59, the reference discloses using the acquired volumetric image data to select and implement a treatment plan, generating 3D images of the target using a Feldkamp algorithm, and employing a high-energy source that operates at 6 and 18 MV (via a cross-referenced article, Jaffray JRO 1999), which falls within the claimed 4-25 MV range.
  • Key Aspects: Petitioner emphasized that Jaffray MICCAI 2001 discloses using the acquired image data to modify treatment by selecting from a set of pre-defined plans to account for prostate rotation, directly teaching the core functionality of the challenged claims.

Ground 2: Obviousness over Jaffray Combination - Claims 57-59 are obvious over Jaffray MICCAI 2001 in view of Jaffray 2001 and Jaffray JRO 1999.

• Prior Art Relied Upon: Jaffray MICCAI 2001 (a 2001 article), Jaffray 2001 (a June 2001 article), and Jaffray JRO 1999 (a 1999 article).
• Core Argument for this Ground:
  • Prior Art Mapping: As an alternative to Ground 1, Petitioner argued that to the extent Jaffray MICCAI 2001 does not explicitly disclose every detail of the "computing unit" recited in claims 57-58, the combination with Jaffray 2001 and Jaffray JRO 1999 renders the claims obvious. These references describe the same underlying Elekta SL20 linear accelerator system and detail the use of a Pentium-based personal computer to control the gantry, x-ray source, and detector readout. The computer transfers data to a storage server via a communications network, fulfilling all functions of the claimed "computing unit."
  • Motivation to Combine: A POSITA would combine the teachings because the references describe different aspects of the same research project on the same hardware. Jaffray JRO 1999 explicitly suggested that integrating dosimetry planning, machine treatment, and imaging control "could significantly alter our current clinical approaches" by increasing treatment efficiency and precision.
  • Expectation of Success: A POSITA would have had a high expectation of success, as integrating computer control and networking components into medical imaging and treatment systems was a standard and routine practice at the time to achieve predictable improvements in workflow and control.

Ground 3: Anticipation over Jaffray Publication - Claims 57-59 are anticipated by the Jaffray Publication under §102.

• Prior Art Relied Upon: Jaffray Publication (International Publication No. WO 01/60236).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that the Jaffray Publication, which was published in August 2001, discloses every limitation of claims 57-59. The publication describes retrofitting a cone-beam CT system onto a radiation therapy system. It explicitly discloses a system with a frame, a rotatable gantry, a flat-panel imager, and both a therapeutic high-energy source (4-25 MV) and a separate cone-beam imaging source. The publication further teaches using the acquired 3D images to "modify current and subsequent treatment plans" and details a computer-controlled system networked together to acquire and store image data, generate a treatment plan, and generate 3D images of the target volume.
  • Key Aspects: Petitioner noted that the Jaffray Publication's disclosure is substantially identical to the Jaffray Application that the patent owner overcame during prosecution only by filing a Rule 131 declaration. However, the Jaffray Publication qualifies as prior art under pre-AIA §102(b) and acts as an absolute bar. The Examiner did not consider this reference despite its disclosure in a belatedly filed IDS.

• Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) contending that claims 57-59 would have been obvious over the Jaffray Publication in view of the general knowledge of a person of ordinary skill in the art.

4. Key Claim Construction Positions

• "high-energy radiation source" and "cone-beam radiation source": Petitioner argued that based on the specification and prosecution history, these terms should be construed to cover systems with two separate sources as well as systems with a single, dual-function source. This broad construction allows prior art disclosing either configuration to meet the claim limitations.
• "frame": Petitioner proposed construing this term as "the structure that supports the gantry." Because the specification does not use the word "frame" but describes a gantry attached to a "drive stand," this construction connects the claim language to the patent's disclosure and to the structures inherent in the prior art linear accelerators.
• "computing unit": Petitioner argued this term should be construed to include "a combination of two or more computers, each of which may perform one or more of the claimed functions." This construction is based on the ’021 patent's disclosure of different functions (e.g., storing data, generating a plan) being performed by different computers (e.g., a simulator computer and a treatment system computer) and is critical for mapping the distributed computer systems of the prior art to the claims.

5. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 57-59 of Patent 7,945,021 as unpatentable.