Cone-beam Computed Tomography of the Paranasal Sinuses: Comparison Study with Multidetector Computed Tomography
PL Kei, JSP Tan, JL Leong, YM Kwok, WEH Lim, LL Chan
Hong Kong J Radiol 2013;16:110-6
DOI: 10.12809/hkjr1313167
Objectives: Cone-beam computed tomography (CBCT) in sinonasal imaging is fairly novel and remains limited to date. This study aimed to compare (1) the image quality of CBCT and multidetector computed tomography (MDCT), and (2) the eye lens dose for paranasal sinus imaging between these two modes of imaging.
Methods:This study was approved by an institutional ethics review board. Sixteen patients underwent CT imaging of their paranasal sinuses for the evaluation of chronic rhinosinusitis using both CBCT and MDCT. The eye lens dose was measured using lithium fluoride thermoluminescent dosimeters during each scan. The scans were read independently by two readers for the presence of sinonasal opacification, artefacts, clarity of osseous structures and soft tissues (based on 5-point grading scales). The interclass coefficient was used to assess interobserver variability.
Results:The mean eye lens dose was 1.0 mGy on CBCT and 1.4 mGy on MDCT. Respective grading scores for opacification, artefacts, osseous structures, and soft tissues were 4.3, 3.9, 4.0 and 2.0 on CBCT compared with 4.2, 4.3, 4.6 and 4.2 on MDCT. Score differences between CBCT and MDCT for artefacts, osseous structures, and soft tissues were statistically significant (p < 0.05).
Conclusion:The image quality of CBCT scans was generally inferior, but adequate for screening purposes in the assessment of opacification and osseous detail. Compared with MDCT scans, the mean eye lens dose with CBCT was also lowered by 25%.
中文摘要
副鼻竇的錐形束CT與多排螺旋CT的比較研究
葛炳林、陳淑萍、梁任靈、郭耀文、林永豪、曾玲玲
目的：鼻腔鼻竇的錐形束CT（CBCT）成像相當新穎，至今仍未普及。本研究旨在比較CBCT和多排 螺旋CT（MDCT）兩種方式的圖像質素以及鼻竇成像中眼晶狀體所受輻射劑量。
方法：本研究已獲機構審查委員會批准。16名慢性鼻竇炎患者同時接受CBCT和MDCT副鼻竇CT掃 描。每次掃描過程中都會使用氟化鋰熱釋光劑量儀測定眼晶狀體的輻射劑量。掃描結果由兩位醫生 獨立閱片，評估鼻竇渾濁化、偽影、骨性結構和軟組織的清晰度（按5點分級表）。以組間相關系數來評估評分者之間的差異。
結果：CBCT的眼晶狀體平均輻射劑量為1.0 mGy，而MDCT則為1.4 mGy。至於鼻竇渾濁化、偽影、 骨性結構和軟組織的清晰度，CBCT的評分分別為4.3、3.9、4.0和2.0，MDCT則分別為4.2、4.3、4.6 和4.2。CBCT和MDCT在偽影、骨性結構和軟組織的清晰度分數差異達統計學意義（p < 0.05）。
結論：CBCT掃描成像的質素普遍較低，但尚可勝任評估渾濁化和細微骨性結構。與MDCT掃描相 比，CBCT的眼晶狀體平均輻射劑量降低了25%。