Nuclear imaging systems and methods with feature-enhanced transmission imaging

• US 6,628,983 B1
• Filed: 10/25/2000
• Issued: 09/30/2003
• Est. Priority Date: 10/25/2000
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Gagnon, Daniel
• Primary Examiner(s): PAIK, SANG YEOP
• Application Number:
  US09/696,153
• Time in Patent Office: 1,070 Days
• Field of Search: 600/407, 600/425, 600/431, 600/436, 250/363.01, 250/363.02, 250/363.03, 250/363.04, 250/363.05, 250/363.1, 378/4, 378/21
• US Class Current: 600/431
• CPC Class Codes: A61B 6/037 Emission tomography
• CPC Class Codes: G01T 1/1648 Ancillary equipment for scintillation cameras, e.g. reference markers, devices for removing motion artifacts, calibration devices adapted for flow studies G01T1/1647

Abstract

A transmission radiation source (30a) radiates at a plurality of energy levels within a specified energy range. The energy range is divided into two or more energy subranges. Detectors (20a-20c) detect the position or trajectory and energy of transmitted radiation and emitted radiation. A sorter (48) sorts the detected radiation into the appropriate energy subrange. Data for each subrange is stored in a plurality of transmission data memories (50a-50n). Reconstruction processors (52a-52n) generate a transmission image representation (54a-54n) representative of each energy subrange. A combine processor (60) weights each energy subrange image representation with an assigned weighting factor (64a-64n) to provide enhancement of at least one feature when the images are combined to generate weighted image representations (72, 74, 76). The plurality of transmission images are also combined with equal weighting to generate an image representation (70) used to generate attenuation correction factors (80) for correcting the emission data (46). A reconstruction processor (84) generates a corrected emission image representation (86). The emission image can be combined with one of the feature-enhanced structural images (72, 74, 76) using a combiner (92) and displayed, allowing the functional emission image to be located with respect to structural or anatomical features. Also, a feature-enhanced structural image (72, 74, 76), can advantageously be used to register the emission image (86) with an image (100) from another modality, such as a computed tomography (CT) image.

Claims

1. A method of generating an image, comprising:

providing a transmission radiation source emitting gamma rays at a plurality of energy levels and directing the emitted gamma rays through a subject to be imaged, the subject attenuating the transmission of the gamma rays;

defining an energy range encompassing the emission energy levels;

dividing the energy range into a plurality of energy subranges;

detecting the gamma rays passing through the subject and falling within the defined energy range;

determining positions and energies of the detected gamma rays;

logging the determined position and energy information into a plurality of image data subsets based on the determined energy of the detected gamma rays, each image data subset corresponding to one of the energy subranges;

repeating the steps of detecting, determining, and logging for a plurality of transmitted rays;

comparing the image data subsets to determine one or both of;

(1) variations in attenuation between different tissue types of the subject as a function of energy, and (2) variations in attenuation within each tissue type of the subject as a function of energy;

based on the determined attenuation variations, assigning a weighting factor to each of the image data subsets and adding the image data subsets together in accordance with their assigned weighting factors to produce a weighted image data set, the weighting factors being assigned so as to enhance at least one structural feature in the weighted image data set; and

generating an feature-enhanced transmission image representation representative of the weighted image data set.

2. The method according to claim 1, wherein the transmission radiation source is barium-133, wherein the defined energy range ranges from about 300 keV to about 400 keV, and wherein the number of energy subranges is from 2 to 8.

3. The method according to claim 1, wherein the enhanced structural feature is selected from the group consisting of bone, soft tissue, and aerated lung tissue.

4. The method according to claim 1, further including:

administering to the subject a gamma radiation-emitting radionuclide composition which emits gamma radiation having a characteristic energy level;

detecting single photon emissions from the radionuclide composition within the subject to generate emission image data;

combining the plurality of transmission image data subsets to generate an attenuation map of the subject;

reconstructing an emission image representation from the emission image data;

during the reconstructing, using the transmission image data to compensate for attenuation; and

combining the emission image representation with the feature-enhanced transmission image representation to generate a superimposed image representation.

6. The method according to claim 1, further including:

administering to the subject a gamma radiation-emitting radionuclide composition which emits gamma radiation having a characteristic energy level;

detecting emissions from the radionuclide composition within the subject to generate emission image data;

combining the plurality of transmission image data subsets to generate an attenuation map of the subject;

reconstructing an emission image representation from the emission image data;

correcting one of the emission image data and the emission image representation using the attenuation map;

providing an image representation from another imaging modality, the other modality image representation being selected from an x-ray computed tomography image representation, a magnetic resonance image representation, and an ultrasound image representation, the other modality image representation being at least partially coextensive with the emission image representation;

identifying common structural features in the feature-enhanced transmission image representation and the other modality image representation;

correlating and aligning the corrected emission image representation and the other modality image representation based on the identified common structural features; and

combining the emission image representation with the other modality image representation to generate a superimposed image representation.

7. The method according to claim 6, wherein the feature-enhanced transmission image representation is a bone-enhanced image representation.

5. A method of generating an image, comprising:

providing a transmission radiation source which transmits rays of radiation at a plurality of energy levels within a range through a subject to be imaged;

dividing the range into a plurality of subranges;

detecting the rays of radiation passing through the subject and falling within the range;

determining positions and energies of the detected rays;

logging the determined position and energy information into a plurality of transmission image data subsets based on the determined energy of the detected rays, each transmission image data subset corresponding to one of the energy subranges;

assigning a weighting factor to each of the transmission image data subsets and combining them together in accordance with their assigned weighting factors to produce a weighted transmission image data set, the weighting factors being assigned so as to emphasize at least one tissue type in the weighted transmission image data set;

generating a feature-enhanced transmission image representation representative of the weighted transmission image data set;

administering to the subject a radiopharmaceutical composition generating emission radiation;

detecting the emission radiation to generate emission image data;

equally weighting the plurality of transmission image data subsets and combining them to generate an attenuation map of the subject;

correcting the emission image data using the attenuation map to generate corrected emission image data;

reconstructing an emission image representation from the corrected emission image data; and

combining the emission image representation with the feature-enhanced transmission image representation to generate a superimposed image representation.

8. A method of diagnostic imaging comprising:

transmitting radiation with a defined energy spectrum through a subject;

converting the transmission radiation which has traversed the subject into electronic transmission data indicative of transmission radiation trajectory and energy;

in accordance with the energy data, sorting the transmission trajectory data into a plurality of energy windows;

reconstructing the transmission trajectory data in each window into a corresponding electronic transmission image representation;

weighting each of the electronic transmission image representations; and

adding the weighted transmission image representations together.

9. The method according to claim 8, further including:

injecting the subject with a radioisotope which emits radiation;

converting emission radiation emitted within the subject into electronic emission data indicative of emission radiation trajectory;

reconstructing the electronic emission trajectory data into an electronic emission image representation.

10. The method according to claim 9, further including:

correcting one of the electronic emission data and the electronic emission image representation with the weighted transmission representations.

11. The method according to claim 9, further including:

with another imaging modality, generating an electronic other modality image representation which clearly depicts a first aspect of the subject;

weighting the electronic transmission image representations to emphasize the first aspect and combining the weighted electronic transmission image representations to produce a combined weighted transmission image representation;

aligning the combined weighted transmission image representation and the other modality image representation; and

combining the emission image representation and the other modality image representation.

12. A gamma camera comprising:

a transmission radiation source for generating radiation in a selected energy range;

a detector for detecting emission radiation emitted from within a subject and transmission radiation from the transmission radiation source which has traversed a subject to be imaged, the subject attenuating the radiation, the detector generating position and energy data;

energy discrimination circuitry connected with the detector, the energy discrimination circuitry sorting detected transmission radiation in accordance with a plurality of energy subranges within the selected energy range;

an electronic storage medium connected with the energy discrimination circuitry, the electronic storage medium storing a plurality of transmission data subsets, the data subsets comprising data grouped by energy in accordance with the plurality of energy subranges;

at least one reconstruction processor connected with the electronic storage medium which generates a transmission image representation for each of the plurality data subsets; and

a combine processor connected with the reconstruction processor which weights the transmission image representations and adds the plurality of weighted image representations together to produce at least one weighted image representation, the weighting being selected to enhance at least one selected feature in each weighted image representation.

13. The gamma camera according to claim 12, further including a display system for converting the weighted image representation into a human-viewable image.

14. The gamma camera according to claim 12, wherein the transmission radiation source is barium-133, wherein the defined energy range ranges from about 300 keV to about 400 keV, and wherein the number of energy subranges is from 2 to 8.

15. The gamma camera according to claim 12, wherein the combine processor further compares the plurality of transmission image representations to determine one or both of (i) variations in attenuation between different tissue types of the subject as a function of energy and (ii) variations in attenuation within each tissue type of the subject as a function of energy, and assigns a weighting factor to each of the plurality of image representations based on the determined attenuation variations.

16. A gamma camera comprising:

a transmission radiation source for generating radiation in a selected energy range;

a detector for detecting emission radiation emitted from within a subject and transmission radiation from the transmission radiation source which has traversed the subject, the detector generating position and energy data;

energy discrimination means connected with the detector, the energy discrimination means sorting detected transmission radiation in accordance with a plurality of energy subranges within the selected energy range;

a storage device connected with the energy discrimination means, the storage device storing a plurality of transmission data subsets, the data subsets comprising data grouped by energy in accordance with the plurality of energy subranges;

a reconstruction processor connected with the storage device, said reconstruction processor generating a transmission image representation for each of the plurality data subsets;

a combination processor connected with the reconstruction processor, said combination processor weighting the transmission image representations and adding the plurality of weighted transmission image representations together to produce at least one weighted transmission image representation, the weighting being selected to emphasize at least one tissue type in each weighted transmission image representation; and

an emission data correction processor for correcting the emission data using the weighted transmission image representation to generate corrected emission image data for reconstruction into an emission image representation with the image reconstruction processor.

17. The gamma camera according to claim 16, further including:

a memory for storing an image representation from another imaging modality, the other modality image representation being at least partially coextensive with the corrected emission image representation;

a registration processor for identifying common structural features in one of the weighted transmission image representations and the other modality image representation, and for correlating and aligning the corrected emission image representation and the other modality image representation based on the identified common structural features; and

an image combiner for combining the emission image representation with the other modality image representation to generate a superimposed image representation.

18. The gamma camera according to claim 17, further including:

a video processor for formatting operator selected portions of the corrected emission image representation, the weighted image representations, and the superimposed image representation into a display format; and

a monitor for converting the display format portions into an operator selected display.