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 .
Response to Amendment
The amendment filed 12/26/2025 was entered. Claims 1, 2, 5, 11, 16 and 19 were amended. New claim 39 depends on amended independent claim 16.
Response to Arguments
Applicant’s arguments, see Remarks, filed 12/26/2025, with respect to the rejection(s) of the independent claim(s) have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Wang, Rothfuss and Cooke, see below.
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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 – 4, 7 –13 and 15 is/are rejected under 35 U.S.C. 103 as being unpatentable over Cho et al. (US Pub. No. 2016/0299240 A1) in view of Wang et al. (US Pub. No. 2015/0331119 A1).
With regards to claims 1 and 11, Cho discloses a method for state detection of an imaging device (i.e. a PET detector 100 may include multiple detector units which may be grouped into separate composite detectors. Each composite detector may include a separate processing unit 111. The composite detectors may operate individually or in concert with other composite detectors. In FIG. 1, for example, each of the detector units 105, 107, 109, may represent a composite detector that includes multiple (for example, a 2×2 array) detector units) [0031] – [0033]; [0038], [0042], [0043], [0046], [0053] (Figure 7) comprising:
obtaining a first background event of a crystal of a detector of an imaging device (i.e., the first background event being related to an inherent radiating particle of the crystal [0022], [0031], [0053];
Notice how as show in figure 4, the LSO background events include the beta and gamma coincidence. By identifying the time-mark information from two detector units E1, E2, the coincidence events may be selected out. The time mark extraction may be done by other methods, for example, the time mark may be identified digitally by capturing the whole timing pulse and post-processing of the timing pulse with a time mark calculation algorithm [0040], [0045] – [0046];
correcting a crystal position look-up table based on the first background event [0050], [0055], [0062], [0065], [0069] – [0075];
correcting an energy state of the imaging device (Figure 7), (ref. A160) [0062];
obtaining a second background event of the crystal, the second background event being related to the inherent radiating particle of the crystal (Figures 11, refs. A220, A230); and
correcting a state of time of flight of the detector based on the first background event and the second background event (Fig. 11) [0062] – [0065], [0069] – [0075]; [0087] – [0088]; also see actually events 202kev and 307Kev in addition to the references A120, A160, A220 and A230 along with figures 7, 11 and 13 within the context as noted above.
Notice how the measured time differences from the events in the first level time alignment is corrected for the time-of-flight that depends on the distance between the two scintillator crystals. Time alignment may be used to calculate individual timing offsets for each of the crystals or detector units. These offsets may then later be deleted from the time marks in the post-processing of events in actual patient or object scans [0069] – [0075].
Looking at the processing device unit 111, which derives time walk correction tables, energy scaling and/or any necessary non-linearity corrections for the detector unit scintillator crystals. The derivation of time walks correction tables, energy scaling, corrections, and time alignment is described in more detail throughout the specification [0038], [0062], [0083] and [0087].
Lastly, Cho teaches intrinsic background events, crystal maps, event-location histograms, and assigning events to scintillator crystals [0030] – [0034]; [0053]-[0055], [0068].
Cho fails to expressly disclose determining, based on the first background even, a single-event image; obtaining, based on the single-event image, a corresponding pixel distribution of a position label of the crystal in the crystal position look-up table in the single- event image; and correcting the crystal position look-up table based on the corresponding pixel distribution of the position label of the crystal in the single-event image.
Wang teaches a PET imaging system is more than just a counter and, in addition to detecting the presence of a scintillation event, the system must identify its location. By properly documenting how light is being distributed to the multiple light sensors, it is possible to assign an event location for any given set of sensor responses [0011].
Wang also teaches coordinates for the x-position and the y-position of a scintillation event are calculated using Anger arithmetic, wherein the x- and y-positions are determined by taking the ratios between the responses of neighboring sensors. Estimating positions from linear combinations of sensor signals leads to distortions, such as pincushion-like distortions. For crystal arrays the decoding of the crystal in which an interaction occurred is generally accomplished through the use of a lookup table generated from a flood map [0012].
Wang discloses that bright spots, peak clusters, high density pixel regions in an event position image or flood map correspond to crystal labels and are used to build or correct a crystal position LUT [0030] – [0034], (Figures 2A – 2C). Lastly, Wang teaches flood-map peaks, high-density regions/LUT crystal decoding [0011] – [00136], [0031] – [0034], (Figures 2A-2C).
In view of the utility, to improve crystal position correction and reduce misassignment of scintillation events, it would be obvious to a person of ordinary skill in the art at the time the invention was made to modify Cho to include the teachings such as that taught by Wang.
With regards to claim 2, Cho discloses wherein the obtaining a first background event of a crystal of a detector of the imaging device includes: obtaining, based on a preset energy window, the first background event of the inherent radiating particle of the crystal received by the detector (fig. 7, ref. A120, A130); [0038], [0041], [0042], [0048], [0055] – [0059]; [0062] and [0072] – [0075].
Notice how energy qualification may entail windowing the results to a range of energy such as the decay energies for Lu. As the graph 807 shows, the energy spectrum is broad enough to qualify event for 511 keV energy so that the timing performance measurement for the detector unit E2 with 511 keV energy qualification may be performed by varying the LE trigger threshold (fig. 7, ref. A120, A130); [0038], [0041], [0042], [0048], [0055] – [0059]; [0062] and [0072] – [0075].
Referring again to FIG. 7, at act A160, using the event data taken with the best VOP and VLE settings, the processing unit 111 derives time walk correction tables, energy scaling and/or any necessary non-linearity corrections for the detector unit scintillator crystals. The derivation of time correction tables, energy scaling, corrections, and time alignment is described throughout the specification in more detail [0030]-[0032], [0057]-[0064]. Notice the singles, coincidence modes and energy windows for background, coincident events [0038], [0040] - [0042], [0056], [0059].
With regards to claim 3, Cho discloses wherein the correcting an energy state of the imaging device comprises: correcting the energy state of the imaging device based on the first background event. (fig. 7, ref. A160); [0062].
Notice that at act A120, the detector units acquire self-activity event data. The event data is acquired at multiple operating voltages and at each operative voltage at multiple leading edge threshold values. The self-activity event data may include the time-mark, energy, and/or location information derived from the background radiation events. The data may be collected, acquired, or derived for each individual pixel or detector unit [0050] – [0055].
See how using the event data taken with the best voltage settings, the processing unit 111 derives time walk correction tables, energy scaling and/or any necessary non-linearity corrections for the detector unit scintillator crystals. The derivation of time walks correction tables, energy scaling, corrections, and time alignment. Basically, the processing unit 111 derives time walk correction tables, energy scaling and/or any necessary non-linearity corrections for the detector unit scintillator crystals. The derivation of time walks correction tables, energy scaling, corrections, and time alignment is described below in more detail [0053], [0055], [0062] – [0081].
With regards to claim 4, Cho discloses wherein the correcting an energy state of the imaging device comprises: obtaining a third background event of the crystal, wherein the third background event is related to the inherent radiating particle of the crystal, and the third background event includes a background single event or a background coincidence event of the inherent radiating particle of the crystal received by the detector; and correcting the energy state of the imaging device based on the third background event (Figs. 2, 4, 5); [0056].
See how the processing unit 111 identifies, from the events, coincidences in adjacent detector units (position and energy for beta energies above 511 keV window and 202 keV and 307 keV gamma events, and time marks for beta and 307 keV gamma events (Figs. 2, 4, 5); [0056].
With regards to claim 7, Cho discloses wherein the correcting a state of time of flight of the detector based on the first background event and the second background event includes: determining a measured time of flight based on the first background event and the second background event; and correcting a time of flight of the detector based on the state of time of flight of the imaging device reflected by the measured time of flight [0032], [0042] – [0063; (Figure 11, see refs A220 and A230).
Notice how the measured time differences from the events in the first level time alignment is corrected for the time-of-flight that depends on the distance between the two scintillator crystals. Furthermore, see how the time alignment may be used to calculate individual timing offsets for each of the crystals or detector units, where an overall time delay for a scintillator crystal may then be the sum of the relative time delay and the time delay of the containing composite detector relative to the other composite detectors. Once the delays are known, the processing unit 111 may calculate correction terms for energy dependent time delays including TOF correction depending on the scintillator crystals [0069] – [0076].
With regards to claim 8, Cho discloses wherein the method further comprises: generating an event time chart based on at least one of the first background event or the second background event; determine a corresponding relationship between TDC values and time based on the event time chart; and determining a TDC scale curve of the imaging device based on the corresponding relationship [0039] [0060] (Figure 10).
Notice how the raw timing signals are used for time mark calculation using digital timing [0039] and how the graphs in FIG. 4 show histograms of energy of all the decay events occurring in both detector units of FIG. 3. FIG. 5 depicts a time-mark difference histogram of the two detector units from FIG. 3 on the graph 501.
FIG. 10 illustrates a timing result including two graphs 1001, 1003 show timing curves for a first detector unit (1001) and a second detector unit (1003). The observed optimal bias voltage is approximately 0.7V above the vendor specified operating voltage (Vop). The bottom two graphs 1005, 1007 are timing curves produced with LSO background coincidence events. The overall curve shapes are well matched while the optimal bias voltage is set at little lower (0.5V above Vop) than the normal timing measurement setup (0.7V above Vop) [0060].
With regards to claim 9, Cho discloses wherein the method further comprises: obtaining a fourth background event of the crystal, the fourth background event being related to the inherent radiating particle of the crystal; generating an event time chart based on the fourth background event; determining a corresponding relationship between a TDC value and a time based on the event time chart; and determining a TDC scale curve of the imaging device based on the corresponding relationship (Figures 2 and 5) [0041], [0044], [0054].
Notice how in FIG. 5 a time-mark difference histogram of the two detector units from FIG. 3 on the graph 501 is depicted. The group of events inside the circle 507 are the coincidence events from the two detector units. The energy spectrums of the coincidence events are displayed in the right two graphs 503 and 505 for E1 and E2 respectively. The two 202 and 307 keV gamma event peaks are more clearly displayed after the coincidence qualification compared to shown in singles mode acquisition in FIG. 4. The 88 keV gammas may be absorbed by LSO and may not scatter into the next detector unit. The Lutetium K-shell fluorescence X-ray (˜53 keV) may appear as another distinctive peak [0039] - [0042].
A Lu-176 beta decay within one detector unit pixel 31 may deposit the beta kinetic energy in the vicinity of the Lu-176 atom 30, while the coincident gamma emission energy is absorbed in a nearby pixel 41 by photoelectric absorption at Lu atom 40. A characteristic x-ray emission from the Lu atom 40 (most often approximately 53 to 54 keV) may escape to a pixel 42 of an adjacent detector unit and deposit its energy there [0043] – [0046].
The coincidence acquisition of intrinsic radiation events by adjacent detector units may be used by the processing unit 111 for calibration of the PET detector and individual detector units' time and energy calibration. The coincidence events may further be used for the setting of parameters to optimize detector performance (e.g. leading-edge thresholds and operating bias voltages to optimize timing performance). The coincidence data acquisition may be used to evaluate the timing performance of the detector units. FIG. 7 depicts a flowchart for setup of a PET detector. Optimizing PET detector performance may involve finding the SiPM bias voltages and/or timing discriminator levels that give a best or sufficient coincidence resolving time in the scanner. A power source may reverse-bias the photo detector array to a bias voltage that is up to a few volts above the breakdown voltage of a photodiode [0047] – [0060].
Setup parameters for the detector units may be determined first. The correction table generation follows for the detector operation with the determined parameters. Signal drift is compensated to maintain all the signal levels to be same to the pre-determined levels with the optimal parameters. Act A120 is repeated one or more times in order to acquire multiple sets of data. For example, background or intrinsic events are detected over minutes, hours, or days, resulting in tens, hundreds, or thousands of detected events [0047] – [0060].
At act A130, the processing unit 111 assigns events within detector units to individual scintillator crystals (pixels). The processing unit 111 may generate histogram event locations for each Voltage and derive crystal region maps in order to assign events. The data received from the detector units is processed to determine the location (e.g., scintillation crystal or pixel) at which the event occurred [0047] – [0060].
With regards to claim 10, Cho discloses wherein the method further comprises: determining, based on the first background event and the second background event, the measured time of flight and a theoretical time of flight; and performing a time-synchronization on a detector module of the detector based on the measured time of flight and the theoretical time of flight [0047] - [0069].
FIG. 11 depicts a flowchart for detector time alignment. The flowchart describes a method for determining the systematic mean timing differences between all scintillator crystals relative to the detector units, and the mean timing differences between the detector units. The measured time differences from the events in the first level time alignment is corrected for the time-of-flight that depends on the distance between the two scintillator crystals. Time alignment may be used to calculate individual timing offsets for each of the crystals or detector units. These offsets may then later be deleted from the time marks in the post-processing of events in actual patient or object scans [0070] – [0081].
With regards to claim 12, see the rejection of claims 1, 2 and 4.
With regards to claim 13, Cho discloses wherein the determining a single- event image based on the background event comprises: determining a single-characteristic-energy-peak event based on the background event, wherein the single-characteristic-energy-peak event includes an event of at least one photon of 597 keV received by the detector; and generating the single-event image based on the single-characteristic- energy-peak event [0033] [0034] [0068] – [0070].
Cho teaches that the isotope Lu-176 occurs naturally in a LSO scintillator. Lu-176 decay produces a radiation event including a beta particle (the maximum energy of 596 keV-596,000 electronvolts; also see figure 2, 4 and 5 for the complete range as claimed) and three gamma (88 keV, 202 keV and 307 keV) particles in coincidence. FIG. 2 illustrates the Lu-176 decay scheme. The radioactive decay may be identified by detectors with certain design characteristics, and used for detector self-setup and self-calibration [0034].
Notice how FIG. 9 illustrates a crystal map for two adjacent detector units. The top two maps 901, 903 are position maps on each detector unit with all the background events acquired (i.e., single mode acquisitions), and the bottom two maps 905, 907 are the ones acquired in ‘coincidence mode’ (i.e., the beta-gamma coincidence events are detected in both detector units) [0033] [0034] [0068] – [0070].
As shown in 905 and 907, the number registered of events is decreasing as the crystal location moves away from the boundaries. This indicates that the detector unit size cannot be too large (>20 mm for LSO) in order to acquire the beta-gamma coincidence events for all the crystals in detector units. The measured time differences from the events in the first level time alignment is corrected for the time-of-flight that depends on the distance between the two scintillator crystals. Time alignment may be used to calculate individual timing offsets for each of the crystals or detector units. These offsets may then later be deleted from the time marks in the post-processing of events in actual patient or object scans [0033] [0034] [0055] [0068] – [0070] [0081].
Most specifically see act A340, the processing unit 111 solves for average timing differences between all detector pairs used in scanner coincidence acquisitions, and/or the average timing differences between all detector unit pairs (i.e., both adjacent and across the ring) used in scanner coincidence acquisitions. The timing differences are used to build time alignment tables. Using both sets of events (self-activity and event data from a phantom) may allow the processing unit 111 to compare difference from both adjacent detector units and those across the ring allowing for a more efficient and quicker configuration [0081].
With regards to claim 15, Cho discloses wherein the method further comprises: determining whether a deviation related to the crystal position look-up table of the imaging device has occurred based on the background event [0042] - [0046]. Also see the rejection of claim 1 with regards to Wang teachings with LUT.
Claim(s) 5, 6, 16 – 20 and 39 is/are rejected under 35 U.S.C. 103 as being unpatentable over Cho et al. (US Pub. No. 2016/0299240 A1) and Wang et al. (US Pub. No. 2015/0331119 A1) in view of Rothfuss et al. (US Pub. No.2015/0301201 A1) and Cooke et al. (US Pub. No.2008/0251709 A1).
With regards to claim 5, Cho discloses wherein the correcting an energy state of the imaging device comprises: generating an energy spectrogram based on energy information of the first background event or the third background event; determining at least one peak position in the energy spectrogram; determining an energy correction state of the imaging device based on the at least one peak position in the energy spectrogram and a corrected peak position corresponding to the at least one peak position; and correcting the energy state of the imaging device based on the energy correction state [0038], [0067] (Figure 5).
Notice how Cho teaches that a radiation event (also referred to as self-activity) in any of the scintillators (202, 204) in a detector unit may trigger the processing unit 111 for data collection. There may be two different types of modes. A first mode, referred to as ‘singles mode’ occurs when data is collected only from the triggers from any single detector unit. A second mode, referred to as ‘coincidence mode’ occurs when the event is collected only when both of the triggers from two adjacent detector units fall into a short time window (for example, a few nano-seconds). Background activity may occur and be acquired at any time, such as (1) prior to a scan and during setup or (2) during a scan or after a scan has completed [0038]. A response and a corrected response may be fit by an exponential function with two model parameters (A and B) [0067] (Figure 5).
Cho fails to expressly disclose e the corrected peak position is determined based on the peak position of the energy spectrogram obtained from a radiation source.
Rothfuss teaches that after source based full setup, baseline intrinsic background data are acquired including a baseline crystal energy spectrum and photopeak data [0029] – [0031], [0039].
Cooke teaches conventional source calibration and uses a radioactive calibration source with characteristic energy and determines gain so that the output signal form characteristic energy radiation is placed into corresponding output energy cannel. [0003] [0029]-[0038] (Figure 2 – 7). Cooke teaches comparing detected peak to an ideal peak and adjusting gain [0035] – [0038].
In view of the utility, to improve the outcome with calibration and adjustments, it would be obvious to a person of ordinary skill in the art at the time the invention was made to modify Cho to include the teachings such as that taught by Rothfuss and Cooke.
With regards to claim 6, Cho discloses wherein the correcting the energy state of the imaging device comprises: determining, based on the first background event or the third background event, at least two energy peak values associated with a nuclide decay of the crystal and ADC values corresponding to the at least two energy peak values ;and determining an energy scale curve of the imaging device based on the at least two energy peak values and the ADC values corresponding to the at least two energy peak values [0003], [0033], [0034], [0042] – [0046], [0088].
Natural emissions (e.g., beta decay) may occur in scintillator material used for PET detectors. Due to emission of gamma rays by the excited daughter nucleus or due to scattering of gamma rays, the original emission may be detected not just in the detector in which the event occurred but any number of adjacent detectors. Each adjacent detector is a detector unit with different control and/or timing detection circuitry. By detecting the emission events in both the detector units in which the decays occurred as well as an adjacent detector unit, one or more setup or operational parameters to be used for one or both detector units is derived [0003], [0033], [0034], [0042] – [0046], [0088].
The background events may be detected separately from other events using the energy window. These background beta decays may be identified and stored. See how an adjustment may be accomplished by changing operating bias voltages, using the amount of signal (energy) shift of the photo peaks, and SiPM design characteristics that determine the change in gain as a function of overvoltage [0003], [0033], [0034], [0042] – [0046], [0088].
With regards to claim 16, see rejections of claims 1, 5, 6 and 11.
With regards to claim 17, Cho discloses wherein the generating an energy spectrogram based on energy information of the background event comprises: generating the energy spectrogram based on the energy information of the background event received by the detector in a single event mode, wherein the energy spectrogram includes at least one of a peak value of a full energy peak or a peak value of a single energy peak (fig. 7, ref. A120, A130); [0038], [0041], [0042], [0048], [0055] – [0059]; [0062] and [0072] – [0075].
Referring again to FIG. 7, at act A160, using the event data taken with the best VOP and VLE settings, the processing unit 111 derives time walk correction tables, energy scaling and/or any necessary non-linearity corrections for the detector unit scintillator crystals. The derivation of time correction tables, energy scaling, corrections, and time alignment is described throughout the specification in more detail [0030]-[0032], [0057]-[0064].
Notice how energy qualification may entail windowing the results to a range of energy such as the decay energies for Lu. As the graph 807 shows, the energy spectrum is broad enough to qualify event for 511 keV energy so that the timing performance measurement for the detector unit E2 with 511 keV energy qualification may be performed by varying the LE trigger threshold (Figure 8) [0059] [0065].
Also in Act 410, the processing unit 111 sets the previously determined optimum Voltages for all detector units. At Act 420, event data is acquired for all detector units that is due to both detector self-activity and a positron emitting source distribution within the PET scanner field of view. At Act 430, the processing unit 111 identifies and separates events coincident with other events in adjacent detector units, which are due to the scintillator self-activity, from other singles events that are due to 511 keV positron annihilation radiation emitted from the scanner field of view. Singles events may be acquired and stored as scan data for later image processing use. At Act 440, the processing unit 111 compares the location of gamma peaks of the self-activity events (202 keV and 307 keV) to the initial setup locations and previously stored self-activity events. At Act 450, the processing unit 111 adjusts detector unit operating parameters to correct for any drift in the gamma peaks. Adjustment may be accomplished by changing operating bias voltages, using the amount of signal (energy) shift of the photopeaks, and SiPM design characteristics that determine the change in gain as a function of overvoltage [0082] – [0088].
With regards to claims 18 and 39, see the rejections of 4 – 6.
With regards to claim 19, see the rejections of claims 3 – 7 and further determining a ratio of the at least one peak position in the energy spectrogram to the at least one corrected peak position; and determining whether the energy correction state of the imaging device is abnormal based on the ratio (Figure 11) (A240) ([0070], [0075], [0076], [0081].
With regards to claim 20, Cho discloses wherein the corrected peak position corresponds to a peak position of at least one photon of 511 keV in the energy spectrum [0037], [0042], [0048], [0056] – [0063], [0070].
Conclusion
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/DJURA MALEVIC/
Examiner, Art Unit 2884
/UZMA ALAM/Supervisory Patent Examiner, Art Unit 2884
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