- 期刊
正子電腦斷層掃描PET/CT球管電壓與球管電流對影像衰減校正的影响評估
The Impact of Tube Voltage and Current on Computed Tomography Attenuation Correction in PET/CT Scan
摘要
背景：傳統正子斷層掃描儀(PET)採用鍺-68((上標 68)Ge)作為穿透式放射源，進行穿透式掃描來計算人體的線性衰減係數作為衰減校正之用。新型的正子電腦斷層掃描儀 (PET/CT)結合了正子斷層與電腦斷層掃描儀，其中電腦斷層掃描影像提供了解剖定位資訊也用於正子斷層掃描的哀減校正。由於電腦斷層掃描時X光球管電壓及電流不同可能會影響衰減校正的結果，本實驗針對球管電壓、球管電流對於正子斷層造影衰減校正係數的影響做探討。 方法：將含碘對比劑Conray依比例稀釋置於正子電腦斷層掃描儀中，在不同電壓及不同球管電流情況下進行掃描，測量不同條件下的線性衰減係數值。 結果：在球管電流測試中，不同球管電流下所測讀出的各組溶液線性表減係數值有一致性。在球管電壓測試中，各組在低密度溶液時所測出的線性衰減係數值有一致性，但在高密度溶液的線性衰減係數值隨著球管電壓不同而有差別。140kV、80mA時對比劑Conray的線性衰減係數值為1.6lE-01±l.24E-031/cm,80kV、80mA時線性衰減係數測讀值為1.32E-01±6.81E-041/cm，比140kV、80mA的側量值減少17.56%。 結論：PET/CT掃描時X光球管電壓可能會造成衰減校正係數計算的差異，為了兼顧衰減校正的正確性及考慮受檢者的輻射劑量，應以高球管電壓、低球管電流方式進行掃描。
並列摘要
Background: Traditionally, (superscript 68)Ge is applied as a transmission source in PET scan in order to calculate the linear attenuation coefficient of human tissue for the correction of attenuation. Nowadays, PET and CT are integrated into a further advanced PET/CT scanner, in which CT not only provides information of anatomical images, but also computed tomography attenuation correction (CTAC). This study aims to evaluate the impact of different tube voltages and currents on CTAC in PET/CT scan since both factors may affect the result of CTAC. Methods: A series of Conray solutions in different concentrations were prepared and scanned under different tube voltages and tube currents in PET/CT scanner. Linear attenuation coefficients under these different conditions were then recorded and compared. Results: Linear attenuation coefficient appears to be consistent under different tube currents. Under different tube voltages, however, linear attenuation coefficient appears to be consistent in low density Conray solutions but varies in high density Conray solutions. Linear attenuation coefficient was 1.61E-01±1.24E-03 1/cm under 140kV and 80mA. Compared to which, linear attenuation coefficient of 1.32E-01±6.81E-04 1/cm under 80 kV and 80 mA was 17.56% less. Conclusion: The X-ray tube voltages seem to affect the result of CTAC more significantly than tube currents. Therefore, in order to obtain an accurate CTAC and also minimize the radiation exposure of patient, it is more reasonable to perform the PET/CT scan under the condition of high tube voltage and low tube current.