Radioassays of yttrium-90 used in nuclear medicine.

Yttrium-90 radioassays are required in nuclear medicine at the gigabecquerel activity level (GBq) for measuring injected activity, and at the becquerel level for measuring individual tissue samples in biodistribution studies. A method of standardizing 90Y for activity using high-efficiency liquid-scintillation counting is described. Solution standards were used to establish the calibration factors for commercial radionuclide calibrators. Detection efficiencies are also presented for liquid-scintillation counting, NaI(T1) bremsstrahlung counting and Cerenkov counting.

Single cervical exostosis. Report of a case and review of the literature.

The authors present a rare case of solitary cervical osteochondroma. Because of its rarity and its predilection for the atlantoaxial area, the diagnosis may be overlooked in evaluating patients having cervical myelopathy. Surgical decompression usually improves the patient's neurologic status.

Spontaneous spinal subdural hematoma: case report and review of the literature.

We report the case of a pediatric patient with a spontaneous spinal subdural hematoma that was not associated with a coagulation abnormality. Six cases have been reported previously. The patient improved after surgical drainage. The possible causes of this rare problem are discussed.

Effects of varying geometry on dose calibrator response: cobalt-57 and technetium-99m.

A joint project between the National Bureau of Standards (NBS) and Biomedical Products Department, E.I. du Pont de Nemours and Company, Inc. compared the indicated activity of (a) cobalt-57 samples in NBS 5-ml ampoules, plastic syringes, Du Pont 27-ml Vial E epoxy- and solution-filled containers, and (b) technetium-99m solutions in NBS 5-ml ampoules, elution vials, and syringes. The measurements were made in ionization chambers from two manufacturers, Capintec and Radcal. The main objective was to examine the use of radionuclides in NBS ampoules and Du Pont Vial E containers as suitable reference sources for ionization chambers used to assay radiopharmaceuticals in elution vials and syringes. The exercise illustrated that regardless of the brand of dose calibrator used, a calibration factor for each geometry should be determined to ensure the highest accuracy. The data show that as much as a 9% difference from the correct activity can be observed for these radionuclides, even when the ampoule reference source gives the appropriate reading.

U.S. National Bureau of Standards/Atomic Industrial Forum radioactivity measurements assurance program.

With the above exceptions, the participants as a whole have done very well during the past 8 years and their measurements should continue to show improvement. Since mid-1981, the agreement between AIF and NBS has been modified to recover the cost of an SRM production program over the next two or three years in order for the program to eventually become self-supporting. This will benefit not only the current sponsors of the program, but also hospitals and other users of NBS radiopharmaceutical SRMs by having these standards available to the public on a regular continuing basis. The participants in this program have derived many benefits since its inception in 1975. Through the measurement of blind samples which demonstrate traceability to NBS, the companies have made it easier to comply with some of the regulatory requirements of the FDA and NRC when applying for new drug applications. They also receive monthly feedback on their measurement procedures so that they can promptly determine if their measurement procedures or instruments have gone awry. If the results are satisfactory, they receive reassurance and confidence that they are making good measurements and providing accurately dispensed products.