Method and apparatus for transmission measurements to form a 3-D image in tomography applications

A system for determining 3-D data of photon attenuation within an object positioned in a positron emission tomograph device, said device having radiation detectors defining a cylindrical surface around the object, said system comprising:

• a helix formed from cylindrical tubing, said tubing having a selected interior configuration helix, said helix having a selected exterior diameter and a selected pitch and positioned adjacent said cylindrical surface defined by said radiation detectors with a portion of each loop of said helix adjacent a face of each one of said radiation detectors, said helix having an inlet and an outlet;
• a hydraulic fluid contained within said helix, said hydraulic fluid having a selected specific gravity;
• a pump for circulating said hydraulic fluid within said helix, said pump having an inlet and an outlet, said pump outlet being in fluid communication with said inlet to said helix;
• a selected source of radiation of a selected configuration for circulating through said helix by circulation of said hydraulic fluid, said radiation passing through the object to be attenuated by the object and received by said radiation detectors of said positron emission tomograph device;
• a storage shield for containing said source of radiation when not being circulated through said helix, said storage shield having an outlet in fluid communication with said inlet of said helix and an inlet in fluid communication with said outlet to said pump, said inlet and outlet of said storage shield having disconnect units whereby said storage shield containing said source of radiation can be disconnected from said helix and said pump;
• detection units containing sensors positioned proximate said inlet and said outlet of said helix to monitor for a presence of said source of radiation entering and reaching said outlet of said helix, said sensors being electrically connected to said pump to repetitively reverse pumping directions of said hydraulic fluid whereby said source of radiation moves in an oscillatory direction within said helix for a selected time;
• a physical stop within said storage shield to selectively hold said source of radiation within said storage shield in the absence of pump operation;
• a further detection unit positioned within said storage shield proximate said stop to ascertain presence of said source of radiation within said storage shield;
• signal processing circuitry connected to outputs of said detectors of said positron emission tomograph device to determine attenuation data of photons from said source of photons during passage through the object;
• and
• further processing circuitry connected to said outputs of said detectors of said positron emission tomograph device and to said signal processing circuitry to apply said attenuation data to data of annihilation photon transmission from within the object to said detectors of said positron emission tomograph device.

A method for determining 3-D data of radiation transmission with an object positioned in a tomograph device, said device having radiation detectors defining a plurality of faces of said radiation detectors, said method comprising:

• forming a conduit from tubing, said tubing having a selected interior diameter, said conduit having a configuration so as to have a portion positioned adjacent each of said plurality of radiation detector faces, said conduit having an inlet and an outlet;
• filling said conduit with a transport fluid;
• pumping said transport fluid within said conduit with a pump, said pump having an inlet and an outlet, said pump inlet being in fluid communication with said outlet of said conduit;
• positioning a selected point source of radioactive radiation within said tubing of said conduit for circulating through said conduit by circulating said transport fluid, said radioactive radiation being directed through the object and received by said detectors of said tomograph device;
• storing said point source of radiation within a storage shield when not being circulated through said conduit, said storage shield having an outlet in fluid communication with said inlet of said conduit and an inlet in fluid communication with said outlet of said pump;
• and
• processing signals received from outputs of said detectors of said tomograph device to determine transmission data of radiation from said source of radiation during passage of said radiation through the object.