DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-5, 10-14, and 18-19 is/are rejected under 35 U.S.C. 103 as being unpatentable over SUZUKI (JP 2013233168 A) in view of SCHILDKRAUT (20200151921 A1), and further in view of Ning (US-PAR-NO: 5999587 A).
Regarding claims 1, 12, and 19. SUZUKI teaches a method comprising:
projecting x-rays to scan a volumetric region of an object, the projecting generates corresponding cone beam computed tomography (CBCT) image data (see Fig. 1, page 3, lines 18-21, the operation X-ray CT imaging is performed on the CT imaging region set by the display unit 61, and the main body 2 that collects projection data and the projection data collected in the main body 2 are processed to generate various images; see Fig. 1, page 3, lines 30-31, the main body 2 includes an X-ray generator 10a that emits an X-ray beam such as an X-ray cone beam BX composed of a bundle of X-rays toward the subject M1);
reconstructing an CBCT volume from the CBCT image data, the CBCT volume representative of the volumetric region and a volume outside the volumetric region (see Fig. 12, page 16, lines 19-24, as shown in FIG. 12, it can be seen that the metal body that appears in the projection image 11 i is substantially removed in the interpolation projection image 31 i by performing the interpolation process. Therefore, according to the volume data (second volume data 32D) obtained by reconstructing the interpolation projection data 31D representing the interpolation projection image 31i, a CT image with reduced metal artifacts can be generated);
generating from the CBCT volume and a projection geometry, maximum intensity projections on a virtual plane (see Fig. 12, page 16, lines 25-29, the first volume data 13D is acquired by the maximum intensity back projection for the projection data acquired by the X-ray CT imaging, and the first volume data 13D is binarized with a required threshold value. By doing so, the metal body corresponding area can be accurately distinguished from the non-metal body corresponding area);
detecting attenuated image areas in the maximum intensity projections corresponding to metal (see page 2, line 25, many line noises (metal artifacts) are generated around the metal body; see page 13, lines 20-33, preferably, the voxel value of the first volume data 13D is determined using the X-ray intensity signal having the maximum intensity among the pixel values detected by the X-ray detector 21. Here, to determine the voxel value of the first volume data 13D, for example, among the pixel values detected by the X-ray detector 21, only a part of the pixel value that protrudes discontinuously is regarded as noise and discarded or ignored. Pretreatment such as treatment may be interposed. Further, calculation processing may be added such as multiplying a pixel value detected by the X-ray detector 21 by a coefficient or giving an addition / subtraction value.
Thus, determining the voxel value using the X-ray intensity signal having the maximum intensity does not necessarily mean that the simple maximum detection signal is directly used as the voxel value of the first volume data 13D. However, it is necessary to determine a voxel value that can clearly distinguish the metal body corresponding region from the non-metal body corresponding region by the subsequent processing such as binarization);
However, SUZUKI does not expressly teach
corresponding the detected attenuated image areas corresponding to the metal to areas of CBCT image data; and reconstructing a final CBCT volume using the CBCT image data by suppression of the areas of the CBCT image data corresponding to the detected attenuated image areas of the maximum intensity projections.
SCHILDKRAUT teaches:
wherein the enlarged CBCT volume spatially extends beyond the volumetric region such that metal located outside the volumetric region is represented in the enlarged CBCT volume (see Fig. 1, 2A, 2B, 4, and 5, SCHILDKRAUT, paragraph 35 and 40, for each forward-projected voxel, from each angular position, a calculated ray extends through the voxel to a corresponding point on the acquired 2-D projection image 36. FIG. 2A identifies this point as pixel location 208. In this way, forward projection traces back from the voxel location 204 to indicate a pixel location 208. In reconstruction processing that is used to form the voxels of the 3-D reconstruction image, the pixel at pixel location 208 contributes to the value of the voxel at voxel location 204; acquired projection image 500, acquired at a different angle. Acquired projection image 500, numbered projection image 123 shows, at a pixel location 502, the corresponding location of the metal feature 302; at a location 504, FIG. 5 shows metal-related artifact 304. In the view of FIG. 5, it is clear that location 502 lies inside the shadow of metal 506 and truly represents a metal feature; location 504 lies outside of metal or other high-density content and corresponds to an artifact);
metal including metal located outside the volumetric region (see Fig. 5, paragraph 40, acquired projection image 500, acquired at a different angle. Acquired projection image 500, numbered projection image 123 shows, at a pixel location 502, the corresponding location of the metal feature 302; at a location 504, FIG. 5 shows metal-related artifact 304. In the view of FIG. 5, it is clear that location 502 lies inside the shadow of metal 506 and truly represents a metal feature; location 504 lies outside of metal or other high-density content and corresponds to an artifact);
corresponding the detected attenuated image areas corresponding to the metal to areas of CBCT image data (see SCHILDKRAUT, paragraph 26, the embodiments of the present disclosure include a method for reducing artifacts in CBCT reconstructions that are caused by metal features and other highly X-ray attenuating materials such as those used for implants that are placed within the body. In the context of the present disclosure, high-density objects that correctly appear as metal in a 2-D projection image or its 3-D reconstruction can also cause what is commonly known as metal artifacts in surrounding portions of the volume image, are termed “metal” objects or “metal features”. This includes objects formed from materials having a relatively high attenuation coefficient and may include some non-metal materials);
reconstructing a final CBCT volume using the CBCT image data by suppression of the areas of the CBCT image data (see SCHILDKRAUT, Fig. 2, paragraph 36, in forward projection processing, every voxel location in the 3-D volume reconstruction can thus be associated with a corresponding pixel location for each 2-D forward projection image. The schematic of FIG. 2A shows a virtual X-ray source focal spot 200. A line 210 extended from source focal spot 200 represents a ray which passes through voxel 204 and intersects 2-D projection image 36 acquired by the detector at a pixel location 208. Voxel location 204 in the reconstruction thus relates to pixel location 208 in the projection image 36. Pixel location 208 is the projection of reconstruction location 204 onto the detector) corresponding to the detected attenuated image areas of the maximum intensity projections (see page 16 and 17, lines 25-36 and 1-3, the first volume data 13D is acquired by the maximum intensity back projection for the projection data acquired by the X-ray CT imaging, and the first volume data 13D is binarized with a required threshold value. By doing so, the metal body corresponding area can be accurately distinguished from the non-metal body corresponding area. Further, the interpolation projection data 31D from which the metal body has been removed can be acquired by performing the interpolation process for the metal body corresponding region specified by this process. According to the second volume data 32D acquired by reconstructing the interpolation projection data 31D, a CT image with reduced metal artifacts can be acquired. Further, by converting the voxel value (CT value) of the metal corresponding region in the second volume data 32D into the voxel value (CT value) of the metal corresponding region in the normal volume data 12D, the second volume data 32D has a metal. The combined volume data 41D obtained by combining the CT value information of the body can be acquired. By generating a CT image from the composite volume data 41D, it is possible to obtain a CT image in which metal artifacts are reduced and a metal body image is reflected; see SCHILDKRAUT paragraph 37, a slice of a reconstruction 300 is shown along with the voxel location of a metal feature 302 and a metal-related artifact 304. As FIG. 3 shows, metal artifacts often appear as light and dark streaks and dark bands around and between highly attenuating objects in the 3-D volume reconstruction. As noted previously, these artifacts are a result of the image reconstruction process and exist only in the reconstructed volume image, not in the scanned object).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify SUZUKI by SCHILDKRAUT to obtain acquired projection image 500, acquired at a different angle. Acquired projection image 500, numbered projection image 123 shows, at a pixel location 502, the corresponding location of the metal feature 302; at a location 504, FIG. 5 shows metal-related artifact 304. In the view of FIG. 5, it is clear that location 502 lies inside the shadow of metal 506 and truly represents a metal feature; location 504 lies outside of metal or other high-density content and corresponds to an artifact, as wherein the enlarged CBCT volume spatially extends beyond the volumetric region such that metal located outside the volumetric region is represented in the enlarged CBCT volume; and further obtain for reducing artifacts in CBCT reconstructions that are caused by metal features and other highly X-ray attenuating materials such as those used for implants that are placed within the body, in order to provide corresponding the detected attenuated image areas corresponding to the metal to areas of CBCT image data; and further obtain a line 210 extended from source focal spot 200 represents a ray which passes through voxel 204 and intersects 2-D projection image 36 acquired by the detector at a pixel location 208. Voxel location 204 in the reconstruction thus relates to pixel location 208 in the projection image 36. Pixel location 208 is the projection of reconstruction location 204 onto the detector and a slice of a reconstruction 300 is shown along with the voxel location of a metal feature 302 and a metal-related artifact 304. As FIG. 3 shows, metal artifacts often appear as light and dark streaks and dark bands around and between highly attenuating objects in the 3-D volume reconstruction, in order to provide reconstructing a final CBCT volume using the CBCT image data by suppression of the areas of the CBCT image data corresponding to the detected attenuated image areas. Therefore, combining the elements from prior arts according to known methods and technique would yield predictable results.
The combination does not expressly teach reconstructing an enlarged CBCT volume.
Ning teaches that in contrast to the prior art approaches, the present invention discloses an exact cone-beam reconstruction system and method using a circle-plus-arc data acquisition geometry in which the locus of a source and a detector is a circle plus an orthogonal arc. In that manner, the best image quality of a cone-beam volume CT is achieved without introducing any additional mechanical complexity compared to a regular CT gantry. If the locus of an x-ray source and a detector is a single circle during cone-beam scanning (single circle cone-beam geometry), an incomplete set of projection data will be acquired. The incompleteness of the projection data results in some unavoidable blurring in the planes away from the central z plane and a resolution loss in the z direction (i.e., Feldkamp, et al.'s algorithm). The reconstruction error due to the incompleteness of the projection data could be up to 40 Hounsfield units (HU) when using Feldkamp, et al.'s algorithm with an 11.degree. cone angle. However, using the data acquisition geometry of the present invention, the locus of an x-ray source and a detector is a circle plus an arc perpendicular to the circle. That corresponds to rotating the x-ray tube and detector on the gantry, and then acquiring the arc projections on a perpendicular arc while tilting the gantry at a relatively small angle (.+-.15.degree. to .+-.30.degree.). Such geometry results in a complete set of data for an object with a 25-40 cm diameter, which corresponds to a 37-60 cm field size at the detector with a magnification of 1.5. Using the system and method of the present invention, the 3-D reconstruction is exact and no image blurring or resolution loss occurs (see Col. 2 and 3, lines 66-67 and 1-27).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the combination by Ning to obtain an exact cone-beam reconstruction system and method using a circle-plus-arc data acquisition geometry in which the locus of a source and a detector is a circle plus an orthogonal arc. In that manner, the best image quality of a cone-beam volume CT is achieved without introducing any additional mechanical complexity compared to a regular CT gantry and geometry results in a complete set of data for an object with a 25-40 cm diameter, which corresponds to a 37-60 cm field size at the detector with a magnification of 1.5. Using the system and method of the present invention, the 3-D reconstruction is exact and no image blurring or resolution loss occurs, in order to provide reconstructing an enlarged CBCT volume. Therefore, combining the elements from prior arts according to known methods and technique would yield predictable results.
Regarding claim 2. The combination teaches the method of claim 1, wherein the enlarged volume is representative of the entire object (see Ning, Col. 3, lines 22-27, geometry results in a complete set of data for an object with a 25-40 cm diameter, which corresponds to a 37-60 cm field size at the detector with a magnification of 1.5. Using the system and method of the present invention, the 3-D reconstruction is exact and no image blurring or resolution loss occurs).
Regarding claims 3 and 13. The combination teaches the method of claim 1, wherein the enlarged volume is generated using filtered or unfiltered back-projection (see SCHILDKRAUT, paragraph 3, the CBCT system captures projection images throughout the source-detector orbit, for example, with one 2-D projection image at every degree increment of rotation. The projections are then reconstructed into a 3-D volume image using various techniques. Among the most common methods for reconstructing the 3-D volume image from 2-D projections are filtered back projection (“FBP”)).
Regarding claims 4 and 14. The combination teaches the method of claim 1, wherein the generating comprises, for each of the maximum intensity projections:
projecting voxels of the enlarged CBCT volume along a virtual projection ray that meet one or more thresholds to the virtual plane (see SCHILDKRAUT, Fig. 2A and 2B).
Regarding claim 5. The combination teaches the method of claim 4, wherein the one or more thresholds comprises a maximum intensity threshold (see SUZUKI, page 14 and 15, lines 35-36 and 1-6, in the binarized CT images 131ix, 131ii, and 131iz, the metal body region Am and the non-metal body region Am are distinguished. In this way, by binarizing the first volume data 13D obtained by the maximum intensity back projection with a required threshold, the metal body can be more accurately compared to the case where the normal volume data 12D is binarized. It can be seen that it is extracted. In the above-described maximum intensity back projection, the voxel value of the specific point 21v in the first volume data is determined based on the X-ray absorbance when the detected X-ray intensity is maximum).
Regarding claim 10. The combination teaches the method of claim 1, wherein the detection of the attenuated image areas is performed using a thresholding process or a neural network (see SCHILDKRAUT, Fig. 6 and 7, paragraph 51, the voxel code values in the reconstruction are, in principle, a measure of the X-ray attenuation coefficient of the material. For example, these values can be expressed in units of inverse cm. Alternatively, the voxel code values are expressed in Hounsfield units. To form the initial metal mask, step 702 can apply a threshold value to the reconstruction voxels, so that voxels that exceed the threshold are included in the metal mask. Preferably, an adaptive threshold is used, such as a threshold that increases in the vicinity of high voxel values).
Regarding claim 11 and 18. The combination teaches the method of claim 1, further comprising configuring a size of the enlarged CBCT volume to the size of a human head (see SUZUKI, page 11, lines 25-28, as can be seen from the CT images 12ix, 12ii, and 12z, a metal crown attached to the tooth surface is detected with relatively bright luminance. Further, metal artifacts (noise on streaks) are generated around the crown. In order to reduce this metal artifact, the image processing apparatus 80 executes a series of processes).
Allowable Subject Matter
Claims 6-9, 15-17, and 20 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Response to Arguments
Regarding limitations of Claims of the instant case in view of the amended Claims and upon further consideration, a new ground(s) of rejection, necessitated by the amendments is made in view of different interpretation of the previously applied references and new prior art as presented in this Office action. Therefore, Applicant’s arguments are moot. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/XIN JIA/Primary Examiner, Art Unit 2663
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