以頭部假體評估二列偵檢器電腦斷層掃描眼球水晶體輻射劑量

Assessment of Eye Lens Radiation Dose with a Head Phantom in Two-detector-row Computed Tomography

10.6200/TCMJ.2014.11.1.08

黃國恩(Guo-En Huang)；尤慧玲(Hui-Ling You)；陳振德(Jen-Dar Chen)

眼球水晶體劑量 ； 熱發光劑量計 ； 電腦斷層 ； eye lens radiation dose ； thermoluminescent ； computed tomography

北市醫學雜誌

11卷1期（2014 / 03 / 30）

77 - 86

繁體中文

目的：本研究想探討做頭部電腦斷層檢查造成眼球水晶體輻射劑量，並分析影響輻射劑量的相關條件因子。方法：本實驗以二列偵檢器（2 detector-row computed tomography, 2-MDCT）電腦斷層掃描儀，首先利用臨床操作頭部電腦斷層掃描條件，繼之再加以改變kVp，掃描模式與更改斷層掃描儀機身在掃描頭部時的傾斜角度。結果：顯示二列偵檢器電腦斷層掃描儀在120kVp的眼球水晶體輻射劑量低於140kVp。使用二列偵檢器電腦斷層掃描儀，在Helical掃描模式顯著高於Axial 掃描模式。若採取不同角度的掃描切面角度，打角度平行上眼眶耳道連線Supraorbitomeatal line （SOML）避開眼球水晶體位置，輻射劑量則是大幅低於打角 度平行眼眶耳道連線Orbito-meatal line（OML）及不打角度的下眼眶耳道連線Infraorbitomeatal line（IOML）。結論：做頭部電腦斷層檢查，利用斷層掃描儀機身在掃描頭部時的傾斜角度避開眼球水晶體位置，有助於大幅降低眼球水晶體輻射劑量。

Objectives: This study evaluated the parameters influencing eye lens radiation dose in head computed tomography (CT). Methods: Different radiation doses during brain CT scan were measured with a 2-slice CT scanner and the phantom in different kVp, scan modes and tilt angles of the gentry. The radiation doses were compared between different protocols. Results: The eye lens radiation dose was lower in the setting of 120 kVp than that of 140 kVp. Helical scan mode delivered significant higher eye lens radiation dose than axial scan mode did. Gentry tilt angle parallel to supraorbitomeatal line (SOML) gave significant lower eye lens radiation dose than parallel to orbitomeatal line (OML) and infraorbitomeatal line (IOML). Conclusion: Using gentry tilt angle parallel to SOML to avoid the eye lens position during head CT scan helps reduce the eye lens radiation dose.