NOMOS Corp. (“NOMOS”) appeals the judgment of the district court granting BrainLAB USA, Inc. and BrainLAB, Inc. (collectively “BrainLAB”) summary judgment of noninfringement of U.S. Patent No. 5,411,026 (“'026 patent”).
Nomos Corp. v. Brainlab, Inc.,
Background
In the context of radiation therapy, a cancerous lesion often shifts position between the time a treatment plan is designed and the administration of treatment. As a result, higher than necessary doses of radiation were historically required to ensure that the entire lesion was exposed. Unfortunately, the excess radiation also caused damage to healthy tissue. The '026 patent, which is owned by NO-MOS, claims a method of fine-tuning the positioning of a patient during radiation treatment so as to maximize the dose to the lesion while minimizing the exposure of surrounding tissue.
The invention operates as follows: First, the position of the lesion is identified in a computerized tomographic (“CT”) scan, from which a physician designs a radiation therapy plan. The patient is then placed on the treatment table of a radiation therapy device, such as a linear accelerator. Because the position of the lesion or the patient may have shifted, an ultrasound probe, which is disposed on the treatment table, is used to generate an ultrasound image of the lesion’s new position. The ultrasound image is then compared with the CT scan. If the lesion has in fact shifted, the physician may adjust the treatment plan accordingly.
NOMOS brought suit against BrainLAB claiming that BrainLAB’s ExacTrac device, which is also a patient positioning system used in the administration of radiation therapy, infringes the '026 patent. BrainLAB moved for summary judgment asserting, inter alia, that the ExacTrac did not meet limitation (a) of claim 1, a means-plus-function claim, which reads:
1. A lesion position verification system for use in a radiation therapy plan, for use with a radiation therapy device, for treating a lesion within a body of a patient, comprising
(a) a means for generating at least one ultrasound image of the lesion in the patient’s body; and
(b) a means for indicating the position, with respect to the radiation therapy device, of the means for generating the at least one ultrasound image when the ultrasound image is generated, whereby the position of the lesion in the ultrasound image can be compared with a position of the lesion in the radiation therapy plan.
'026 patent, col. 12,11. 7-19 (emphasis added). Specifically, BrainLAB alleged that the ExacTrac device utilizes a handheld ultrasound probe, while the means for generating the ultrasound image in the '026 patent must be affixed to the treatment table so that its orientation is maintained with respect to the axis of the treatment table.
After a
Markman
hearing, the district court construed the corresponding structure of limitation (a) of claim 1 as a “fixed ultrasound probe and a bracket or fixation device that maintains the ultrasound probe perpendicular to the treatment table and constrains it to rotate or move along the axis of the table in order to generate an ultrasonic image, and equivalent struc
*1367
tures.”
Nomos Corp. v. Brainlab, Inc.,
Discussion
“We review a district court’s grant of summary judgment
de novo.” Caterpillar Inc. v. Deere & Co.,
We review the district court’s construction of the “means for generating” limitation
de novo. See Cardiac Pacemakers, Inc. v. St. Jude Med., Inc.,
The parties agree that claim 1 is a means-plus-function claim and is, therefore, governed by 35 U.S.C. § 112, ¶ 6. Thus, we must identify both the claimed function and the corresponding structure.
See Micro Chem., Inc. v. Great Plains Chem. Co., Inc.,
The parties also agree that the claimed function of limitation (a) of claim 1 is “generating at least one ultrasound image of the lesion in the patient’s body.” They disagree, however, with respect to the determination of corresponding structure. NOMOS contends that the corresponding structure is an ultrasound probe and nothing more. To support this contention, NOMOS refers to the specification, which states, “Preferably the means for generating 420 an ultrasound image 421 is a conventional, commercially available ultrasound probe 422.” '026 patent, col. 7, 11. 8-10. NOMOS further argues that the principle of claim differentiation prohibits including a fixation device in the corresponding structure of limitation (a) of claim 1 because dependent claim 3, which claims a “means for mounting the ultrasound probe to the radiation therapy device,” would otherwise be rendered superfluous.
BrainLAB, agreeing with the district court’s construction, asserts that the corre *1368 sponding structure should include both an ultrasound probe and a fixation device that secures the probe to the treatment table. To support its argument, BrainLAB notes that throughout the patent the ultrasound probe is described as including a fixation device and that an ultrasound probe alone would be incapable of performing the agreed upon function.
We look to the specification of the '026 patent to determine the corresponding structure.
See Smiths Indus.,
There are several sections of the patent that convince us that the corresponding structure should include a fixation device as held by the district court. The patent states “that the means for generating the ultrasound image may be an ultrasound probe,
including
a means for mounting the ultrasound probe to a radiation therapy device.” '026 patent, col. 3, 11. 39-42 (emphasis added). This language indicates that the invention envisioned and claimed by the applicant included a fixation device that secures the probe to the treatment table. This is the only embodiment of the invention described in the '026 patent. As a result, the corresponding structure is limited to that embodiment, which includes a fixation device, and its equivalents.
See Intellectual Prop. Dev., Inc. v. UA-Columbia Cablevision of Westchester, Inc.,
NOMOS counters that limitation (a) of claim 1 should not be interpreted so as to include a fixation device because dependent claim 3 claims a “means for mounting.” This argument, which relies on the concept of claim differentiation, is unavailing. First, as in
Laitram,
our interpretation of the corresponding structure comes from the written description, not from dependent claim 3 and, therefore, the “prohibition against reading limitations from a dependent claim into the independent claim is not violated.”
Having determined the function and corresponding structure of limitation (a) of claim 1, we turn next to the issue of infringement, which is a question of fact.
Caterpillar,
With respect to function, there is no dispute that the ExacTrac device “gen-erat[es] at least one ultrasound image of the lesion in the patient’s body.”
See Ishida Co., Ltd. v. Taylor,
We also determine that there is no infringement under the doctrine of equivalents. When there is no literal infringement of a means-plus-function claim because the accused device does not use identical or equivalent structure, as in this case, the doctrine of equivalents might come into play when after-developed technology is involved.
See Ishida,
Conclusion
Accordingly, the judgment of the district court is affirmed.
AFFIRMED
Notes
. The district court construed several other portions of the patent. Because our determination with respect to limitation (a) of claim 1 is dispositive, the additional grounds for decision provided below are not addressed.
See Laitram Corp. v. Rexnord, Inc.,
