²²³Ra イメージングにおける異なるコリメータとエネルギーウインドウの設定が総合感度および総合空間分解能に与える影響

抄録

Objective: The present study aimed to reveal the influence of combination of different collimators and energy windows on the planar sensitivity and the spatial resolution during experimental ²²³Ra imaging, and to determine optimal imaging parameters. Methods: A vial type source containing ²²³Ra solution (4.55 MBq / 5.6 ml) was placed in the air at 100 mm away from the collimator surface. Planar images were acquired with LEHR, LMEGP, ELEGP and MEGP collimators on two dual-head gamma cameras (Symbia intevo (Siemens) and Infinia 3 (GE)). We compared three energy window combinations: 1) single window at 82 keV, 2) double window at 82+154 keV, 3) triple window at 82+154+270 keV. The energy spectrum, the sensitivity and the spatial resolution, such as full-width at half-maximum (FWHM) and full-width at tenth-maximum (FWTM), of each collimator were assessed. Results: Five energy spectra (at around 82, 154, 270, 351 and 405 keV) were essentially observed among four collimators. The sensitivity was high for LEHR collimator, then ELEGP and LMEGP collimator was 3–4 fold, which is greater than MEGP collimator. The 82 keV energy window of four collimators has best spatial resolution. Moreover, the spatial resolution of the 82 keV energy window with LMEGP and ELEGP collimator was almost equal to that of the triple window with MEGP collimator. Conclusions: Optimal imaging parameters were single energy window using LMEGP or ELEGP, and then triple energy window using MEGP collimator.