论文部分内容阅读
用分角线技术拍摄的普通根尖片在对同一牙位重复拍片时,因每次投照的角度、曝光、冲洗条件不固定,不能进行比较。因而不能满足纵向临床观察和研究的需要。Grondahl(1983)首次提出根尖片数字减影技术(DSR),它的特点是:定位投照;计算机辅助的模-数-模转换,并自动减影,最终显示骨量的微细变化,因而是动态地定量观察牙槽
Ordinary apical films taken with cornering technique are not suitable for repeated exposure to the same tooth because exposure, washing conditions are not fixed and can not be compared. Which can not meet the needs of longitudinal clinical observation and research. For the first time, Grondahl (1983) proposed a digital subtraction technique (DSR) of the apical phalanx, which is characterized by: location mapping; computer-assisted modulo-digital-to-analog conversion and subtraction automatically to eventually show subtle changes in bone mass It is dynamic quantitative observation of alveolus