全景片切牙根部模糊的原因及解决方法  

Blurring of the incisor root on pantomography: causes and countermeasures

作　　者：胡望远[1] 刘江[1] 舒锦尔[1] 沙水泉[1] 肖根仕[1] 李伟良[1] 钟伟光[1] 虞升华[1] 厉玲玲[1] 林开勤[1] 杨正汉[2] 

机构地区：[1]浙江省金华市中心医院放射科,321000 [2]卫生部北京医院放射科

出　　处：《中华放射学杂志》2003年第12期1110-1112,共3页Chinese Journal of Radiology

摘　　要：目的　研究全景片切牙根部模糊的原因及解决方法。方法　 (1)回顾分析 4 0 0份成人全景片 ,求出切牙根部模糊的全景片所占的比例 ;(2 )用实验方法测出全景摄影图像层面各点厚度及P12 (Program 12 )切牙小区域摄影的图像层面厚度 ;(3)使用 4mm直径的钢珠间隔 5mm镶嵌在一塑料直尺上模拟切牙进行不同倾斜角度全景摄影 ,检测切牙倾角对全景摄影时图像清晰度的影响 ;(4 )对4 0例成年志愿者进行常规全景摄影及P12切牙小区域摄影 ,常规全景摄影有切牙根部模糊者进行调整角度后全景摄影。结果　 (1) 4 0 0份成人全景片中 ,318份存在切牙根部模糊 ,占 79.5 %。 (2 )全景摄影图像层面各点的厚度是不同的 ,切牙区最薄 ,为 0 .7cm ,P12切牙小区域摄影的图像层面厚度为 2 .4cm。 (3)直尺上钢珠的清晰度与直尺的倾斜角度有关 ,倾角过大即可产生模糊。 (4 ) 4 0例志愿者的常规全景摄影中 32例有切牙根部模糊 ,调整头颅倾斜角度后可使牙根显示清晰 ,P12切牙小区域摄影全部清晰。结论　全景片上切牙根部产生模糊的主要原因是图像层面未能包含切牙全长。调整头颅倾斜角度而改变切牙倾斜角度 ,或改变断层扫描轨迹增加图像层面厚度使切牙全长均位于图像层面内 ,即可避免切牙根部的模糊。Objective To investigate the causes of blurring of the incisor root on pantomography and its countermeasures. Methods (1) Pantomography of 400 cases was reviewed, and the ratio of blurring of the incisor root was calculated. (2) An experimental study was designed to measure the slice thickness in different regions of pantomography and on regional tomography of the incisor teeth. (3) Pantomography was performed in a ruler inlaid with several steel balls (4 mm in diameter and 5 mm interval) in different tilt angles. (4) Pantomography and regional tomography of the incisor teeth were obtained in 40 volunteers. After the skull tilt angle was adjusted, pantomography was performed again in the volunteers with blurring incisor root on previous pantomography. Results (1) Blurring of the incisor tooth on pantomography was found in 79.5% of all cases (318/400). (2) Slice thickness was different in different regions of pantomography, and it was 7 mm in the incisor region. The slice thickness was 24 mm on regional tomography of the incisor teeth. (3) The clearness of the steel balls was related with the tilt angle of ruler. A great tilt angle resulted in blurring of the steel balls. (4) Blurring of the incisor root on pantomography was observed in 32 of 40 volunteers, while the incisor root was clear on regional tomography in all volunteers. The incisor root was showed clearly on pantomography with an adjusted tilt angle. Conclusion The main cause of blurring incisor root on pantomography is that the tomographic slice does not include the full-length incisor. To obtain excellent pantomography with clear incisor root, the skull can be adjusted to get a suitable tilt angle of the incisor, or the slice thickness can be increased to include full-length incisor in tomographic slice.

关 键 词：全景片 切牙根部模糊 原因 解决方法 质量控制 X线检查 

分 类 号：R816.98[医药卫生—放射医学]