Effect of surrounding materials on iterative reconstruction-based line-source response function, and annihilations outside the source assessed by a small animal PET scanner.

Objective: The aims of this study were (1) to evaluate the effect of surrounding materials on the iterative reconstruction-based line-source response function (IR-RF) of (18)F, (11)C, (13)N, and (15)O using a preclinical PET system, and (2) to determine whether and how annihilation outside the source can be visualized experimentally.

Methods: We performed all the measurements using the LabPET-8 PET/CT subsystem built-in the Triumph II platform (TriFoil Imaging, Inc., Northridge, CA, USA).

A new method for measuring dynamic change of tracer distribution using dynamic single photon emission tomography with a slip-ring rotational gamma camera.

The clinical applicability of dynamic single photon emission tomograpy (SPET) using a dual-head gamma camera equipped with a slip-ring rotational mechanism, referred to as serial SPET, was examined in the present investigation. Serial SPET enables the production of tomographic images for any arbitrary time frame from an arbitrary range of data to 360 degrees. In a pre-clinical evaluation, a correlation between radioactivity concentration and serial SPET counts was evaluated in a phantom with continuous changes in 99mTc concentration.

[Brain uptake ratio as an index of cerebral blood flow obtained with 99mTc-ECD].

A new index of cerebral blood flow (brain uptake ratio, BUR) using 99mTc-ECD was developed and evaluated in 66 patients (132 cerebral hemispheres). BUR was calculated from brain count in anterior planar image (60-80 sec after injection of 99mTc-ECD) divided by the summation of the count of aortic arch during first transit of radionuclide. BUR correlated well with brain perfusion index (BPI) obtained with Patlak plot method (r = 0.

[Modifications of fractional uptake method for 123I-IMP].

We intended to improve the fractional uptake (FU) method which was developed to quantify cerebral blood flow using 123I-IMP without blood sampling. The quantification of cardiac output (CO) using first-pass data was adapted to FU method while the original FU method used CO which was estimated from the body surface area of patients. Time-radioactivity curves of the lungs and brain were separately obtained by a small-field-of-view gamma camera.

[Reduction of radiation dose to the worker in preparing the radiopharmaceutical solution by a simple shielding equipment].

In order to reduce radiation dose to the hands of examiners who prepare and aspirate radiopharmaceuticals, we made a prototype of simplified manually-operated dispense system, which the syringe and the vial shield with lead were set in the small box made of lead and lead glass. The result showed that our dispense system allowed substantial reduction of radiation dose to the hands and rapid preparation of radiopharmaceuticals compared with the conventional lead shield syringe system, and allowed closer operation, smaller dead volume and lower cost compared with the conventional automatic system.