探討雙源與320切電腦斷層肝三相之影像品質與輻射劑量:假體實驗

過去的電腦斷層都為單能量螺旋式掃描，近來Siemens CT將雙能量掃描導入肝三相檢查動脈相，提高了病灶之診斷率。而Toshiba CT所擁有320排偵檢器，其單圈最大掃描範圍可達16 cm，因此衍伸了寬體積掃描。本研究最主要目的，使用Siemens CT及Toshiba CT之臨床肝三相檢查掃描組合評估受檢者單次檢查所受之輻射劑量，使用Siemens CT的單能量及雙能量掃描及Toshiba CT的螺旋式及寬體積式掃描搭配過濾反投影法及疊代法的影像重組技術評估影像品質。 本實驗使用Rando假體填入熱發光劑量計，以評估臨床肝三相檢查掃描之輻射劑量。亦修改臨床Topogram之掃描設定，評估不同Topogram設定之肝三相檢查掃描之輻射劑量。使用Catphan假體搭配自製體環評估Siemens CT的單能量及雙能量掃描及Toshiba CT的螺旋式及寬體積式掃描的影像品質，分別分析在電腦斷層的自動管電流調控系統所掃描Catphan假體之影像，及設定12種輻射劑量掃描Catphan假體之影像，以了解各掃描方式之劑量與影像品質關係。 在臨床肝三相檢查掃描組合中單次檢查之全身有效劑量較低者為Siemens CT，其次為Toshiba CT寬體積式掃描，劑量較大的為Toshiba CT螺旋式掃描。在FOMCNR之AEC mode中，若使用FBP影像重組技術時，在Siemens CT的雙能量檢查可提供最佳之FOMCNR，其次為Toshiba CT為螺旋式掃描。若疊代法重組影像時，Siemens CT的雙能量檢查亦可提供最佳之FOMCNR，其次為單能量及Toshiba CT的寬體積式掃描。

The traditional spiral scans of computer tomography using a single energy, and recently the Siemens CT using dual-energy scanning protocol apply to arterial phase scan of liver triple-phase examination, and improve the diagnosis rate of the lesion. The Toshiba CT has a 320-row detector, the lap maximum scan range of up to 16 cm, can be an extension of the wide volume scan. The study use Siemens CT and Toshiba CT to evaluate the effective dose of the liver triple-phase examination. In image quality evaluation, the study use the dual energy mode of Siemens CT and the wide-volume mode of Toshiba CT to scan Catphan phantom and reconstruct image by FBP and IR mode to compare their traditional spiral scan mode. The Rando phantom filled with TLDs to evaluate dose in the liver triple-phase examination. In addition, the experiment also used a single topogram scan protocol to assess the doses of the liver triple-phase examination. The Catphan phantom with self-made body annulus phantom was scanned by the AEC system and the 12 manual dose modes to evaluate the image quality of the four scan mode. In clinical examinations of the liver triple-phase, the lowest effective dose is in Siemens CT, the next is the wide-volume mode of Toshiba CT and the helical mode of Toshiba CT. In the FOMCNR of AEC mode reconstructed by FBP method, the best of FOMCNR is the dual energy scan mode of Siemens CT, and the next is the helical mode of Toshiba CT. If we use the IR mode of image reconstructions, the best of FOMCNR is also the dual energy scan mode of Siemens CT, and the next is the single energy scan mode of Siemens CT and the wide-volume mode of Toshiba CT.