In conventional positron emission tomography control systems, an individual dose of a premeasured radiotracer is administered to an individual patient. The individual premeasured radiotracer is prepared by a radiotracer supplier (commonly called a radiopharmacy). A Cyclotron is used most commonly to prepare the radiotacer. The radiotracer is delivered to a medical facility that administers the individual premeasured radiotracer as a radiopharmaceutical. The individual premeasured radiotracer is prepared by the radiotracer supplier in accordance with a prescription from a physician. The prescription includes a prescribed amount of radioactivity at a future time and a date of the prescribed administration in a known volume of a liquid suitable for injection into a living subject.
The conventional process of radiotracer production in a cyclotron performed by a radiotracer supplier is as follows: The radiotracer supplier irradiates a target material in the cyclotron with a beam of protons or deuterons to produce a desired amount of radioactivity in the target material. The extent of irradiation is planned to fulfill the need of radioactivity at the prescribed future time and date. The irradiated target material is a radioisotope. Examples of cyclotron produced radioisotopes include nitrogen-13, fluorine-18, carbon-11 and oxygen-15. Often, compounds are bond to the radioisotope to produce radiotracers such as fluorodeoxyglucose (FDG) which is produced using fluorine-18. Other radiotracers include nitrogen-13 ammonia which is used in myocardial applications, carbon-11 tracers which are commonly used in neurologic applications; and oxygen-15 gas as well as tracers derived from it which are commonly used in blood flow applications. FDG is by far the most commonly used radiotracer and has a half life of 109 minutes allowing for its distribution from a centralized radiopharmacy to multiple imaging sites.
Typically the radiotracer supplier packages the radiotracer in an individual dose vial such as in the case of FDG. Thereafter, the individual dose vial is packaged in an individual lead-shielded container. Each lead-shielded container weighs approximately 50-60 lbs. Typically, the radiotracer supplier will prepare a number of individual dose vials for each medical facility each day. Each of the dose vials are packaged in an individual container. As a result, a number of 50-60 lb containers will be delivered to each medical facility each day. Furthermore, in order to accommodate unplanned changes in the needs of radiotracer by a medical facility, as well as to meet other logistical needs, conventionally two or more deliveries of individual dose vials in individual containers will be made each day. The two or more deliveries are typically performed in the early morning before 7 am, and in the late morning between 10 am and 11 am, or as desired by the medical facility. The cost and overhead of preparing individual dose vials, packaging and transporting a number of the heavy containers twice a day is significant.
In addition, when the radiopharmaceutical is administered to the patient, the PET technician is exposed to radioactivity. The PET technician connects an intravenous tube (IV) into the radiopharmaceutical container, inserts a needle at the other end of the IV into the patient, starts the infusion of the radioisotope through the IV, monitors the progress of the infusion, and ends the infusion, all the while remaining close-by the patient and the IV containing the radiopharmaceutical. This close proximity to the radioactivity results in numerous low levels of exposure to radioactivity that can be harmful to the health of the PET technician.
Quality control of the amount of radionuclic and chemical purity of the bulk batch is typically performed under manual direction and control by the supplier. As a result of the manual aspects of the quality control, the standards of quality control are subjective.
Furthermore, conventional systems can be slow, which requires that the radioisotope material must be produced at a much stronger level of radioactivity in order to have the required amount of radioactivity at the time of injection.
A number of radioisotopes have such short half-lives, that the radioisotope must be produced by a cyclotron in close proximity to the medical facility. Nitrogen-13 ammonia has a half-life of 10 minutes, and oxygen-15 has a half-life of 2.1 minutes. Due to its short half-life, nitrogen-13 ammonia and oxygen-15 necessitate production in close proximity to the medical facility site. Therefore, the use of nitrogen-13 ammonia and oxygen-15 for PET is limited to those sites that have immediate access to its production.
More generally, conventional systems are sequential and step wise. Major functions, such as the production of the radiotracer, and the injection of the radiopharmaceutical, collection of clinical data following a specific imaging protocol, are managed by separate organizations, by different personnel, often in a somewhat uncoordinated and disjoint manner.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art to reduce the number of individual dose vials and shielded containers that radioisotope suppliers prepare and deliver to each medical facility each day. There is also a need to reduce the number of delivery trips that a radiotracer supplier makes to each medical facility each day. In addition, there is a need to reduce the exposure of people, such as PET technicians, to radioactivity during the manual steps of administering a radiopharmaceutical to patients. There is also a need to improve the quality control of the administration of radiopharmaceuticals to patients. Moreover, there is a need to reduce the disjoint management and control of the functions of preparing and injection radioisotopes into patients. Furthermore, there is a need to provide a convenient method for on-site production and administration of nitrogen-13 ammonia radiopharmaceutical for cardiac studies.