Patent Number: 
Section: claims

1. A medical imaging system comprising:a positron emission tomography (PET) imaging apparatus;a computed tomography (CT) imaging apparatus including a rotatable gantry; anda radioactive source loader attached to the rotatable gantry and being rotatable therewith, the radioactive source loader including:a radioactive source configured to calibrate the PET imaging apparatus when in an exposed position; anda storage shield to house the radioactive source and shield the ambient environment from radiation produced by the radioactive source when the radioactive source is in a stored position;wherein the radioactive source loader is configured to selectively translate the radioactive source between the exposed position and the stored position so as to selectively expose the radioactive source to calibrate the PET imaging system. 2. The medical imaging system of claim 1 wherein the radioactive source comprises a radioactive pin; andwherein the radioactive pin is configured to travel in a one-dimensional motion relative to the storage shield so as to be selectively housed therein. 3. The medical imaging system of claim 1 wherein the radioactive source further comprises a radioactive wire having at least one radioactive insert embedded therein. 4. The medical imaging system of claim 3 wherein the radioactive source loader further comprises:at least one roller having the radioactive wire wound thereabout; anda control motor to turn the at least one roller to wind and unwind the radioactive wire into and out of the storage shield. 5. The medical imaging system of claim 4 wherein the radioactive source loader further comprises a tubular plastic housing attached to the storage shield configured to straighten the radioactive wire when unwound out of the storage shield. 6. The medical imaging system of claim 3 wherein the at least one radioactive insert further comprises at least one of a low radioactivity insert and a high radioactivity insert. 7. The medical imaging system of claim 1 further comprising at least one additional radioactive source loader attached to the rotatable gantry. 8. A combination CT/PET scanning system comprising:a PET scanner to acquire a PET image of a patient, the PET scanner having a detector array therein;a CT scanner to acquire a CT image of the patient, the CT scanner having a rotatable gantry; anda calibration device attached to the CT scanner and that rotates with the rotatable gantry to calibrate the detector array in the PET scanner, the calibration device including:a radioactive source;a radiation shield positioned about the radioactive source to selectively shield radiation produced by the radioactive source; anda means for selectively translating the radioactive source into and out from the radiation shield between a stored position and a calibration position;wherein the means for selectively translating the radioactive source translates the radioactive source out from the stored position within the radiation shield to the calibration position when calibration of the detector array is desired. 9. The combination CT/PET scanning system of claim 8 wherein the radioactive source comprises a radioactive source pin, the radioactive source pin being movable along a longitudinal axis of the radiation shield so as to be removable in part therefrom. 10. The combination CT/PET scanning system of claim 8 wherein the calibration device comprises:a first spool positioned within the radiation shield;a radioactive strip wound about the first spool, the radioactive strip having at least one radiation segment formed therein;a means for winding and unwinding the radioactive strip from the first spool; anda guide tube extending out from the radiation shield to guide the radioactive strip out from the radiation shield when unwound from the first spool. 11. The combination CT/PET scanning system of claim 10 wherein the calibration device further comprises:a second spool positioned within the radiation shield and having a portion of the radioactive strip wound thereabout; anda tensioning member positioned outside the radiation shield to tension the radioactive strip between the first and second spools and expose a portion of the radioactive strip outside the radiation shield. 12. The combination CT/PET scanning system of claim 10 wherein the at least one radiation segment further comprises at least one of a high radiation segment and a low radiation segment. 13. The combination CT/PET scanning system of claim 10 wherein the means for winding and unwinding the radioactive strip from the first spool comprises an electric motor. 14. The combination CT/PET scanning system of claim 8 comprising a plurality of calibration devices positioned around the rotatable gantry, wherein the plurality of calibration devices rotate with the rotatable gantry to selectively calibrate the detector array in the PET scanner. 15. A method of constructing a medical imaging device comprising the steps of:positioning a CT image scanner in a fixed position relative to a PET image scanner, the CT image scanner including a rotatable gantry therein; andmounting a radioactive source loader on the rotatable gantry of the CT image scanner that is configured to calibrate the PET image scanner, wherein mounting the radioactive source loader further comprises:affixing a radiation shield to the rotatable gantry;positioning a radiation source within the radiation shield, such that the radiation shield shields the radiation source from an ambient environment when the radiation source is not in use calibrating the PET image scanner; andpositioning at least partially within the radiation shield, a means for selectively translating the radiation source into and out from the radiation shield for selective storage of the radiation source and calibration of the PET image scanner. 16. The method of claim 15 wherein positioning the radiation source further comprises positioning a radioactive source pin within the radiation shield, wherein the radioactive source pin is configured to selectively extend out from the radiation shield. 17. The method of claim 15 wherein positioning the radiation source further comprises:positioning at least one roller within the radiation shield;winding a radioactive tubing about the at least one roller; andwherein the radioactive tubing is rolled and unrolled from the at least one roller to selectively extend out from the radiation shield.