CAJ | 학술논문

目的　通过实验测试增感屏-胶片组合体系的威纳频谱(Wiener spectrum，WS)，评价X线照片的粒状性。方法　制作CaWO4屏- Kodak片、BaFCl:Eu屏- Kodak片、T颗粒技术3种增感屏-胶片组合体系的10 cm×10 cm粒状性抽样照片，用显微密度计扫描，获得10万个密度值，作为离散随机信号来处理，用快速傅立叶变换（fast Fourier transform，FFT）计算WS。结果　（1）BaFCl:Eu屏-Kodak片的WS值：当空间频率为0.1 LP/mm时,WS值为8.26×10-5mm2,分别是T颗粒技术、CaWO4屏- Kodak片取得照片WS值的2.25倍、1.53倍；当空间频率为0.5 LP/mm时,WS值为5.23×10-5 mm2,分别是T颗粒技术、CaWO4屏- Kodak片取得照片WS值的2.68倍、1.42倍。（2）管电压由80 kV增加到90 kV时，T颗粒技术在各频率下的WS值均有所增加。结论　BaFCl:Eu屏- Kodak片组合体系的WS最大，T颗粒技术改善了照片的斑点问题，其WS值最小,故最好是采用T颗粒技术。
목적　통과실험측시증감병-효편조합체계적위납빈보(Wiener spectrum，WS)，평개X선조편적립상성。방법　제작CaWO4병- Kodak편、BaFCl:Eu병- Kodak편、T과립기술3충증감병-효편조합체계적10 cm×10 cm립상성추양조편，용현미밀도계소묘，획득10만개밀도치，작위리산수궤신호래처리，용쾌속부립협변환（fast Fourier transform，FFT）계산WS。결과　（1）BaFCl:Eu병-Kodak편적WS치：당공간빈솔위0.1 LP/mm시,WS치위8.26×10-5mm2,분별시T과립기술、CaWO4병- Kodak편취득조편WS치적2.25배、1.53배； 당공간빈솔위0.5 LP/mm시,WS치위5.23×10-5 mm2,분별시T과립기술、CaWO4병- Kodak편취득조편WS치적2.68배、1.42배。（2）관전압유80 kV증가도90 kV시，T과립기술재각빈솔하적WS치균유소증가。결론　BaFCl:Eu병- Kodak편조합체계적WS최대，T과립기술개선료조편적반점문제，기WS치최소,고최호시채용T과립기술。
Objective　To evaluate the mottle of screen-film by means of studying the Wiener spectrum(WS) of screen-film. Methods　Three kinds of films including CaWO4 screen-Kodak film, BaFCl:Eu screen-Kodak film, and T-grain were used in the study. WS values were calculated on the 100 thousand data obtained by scanning on micro-densimeter for every film processed as discrete signal by using fast Fourier transform (FFT). Results　(1) The WS value of BaFCl:Eu screen-Kodak film was 8.26×10-5 mm2 when the spacial frequency was 0.1 LP/mm, which was 2.25 times of T-grain′s, and 1.53 times of CaWO4 screen- Kodak film′s. The WS value of BaFCl:Eu screen-Kodak film was 5.23×10-5 mm2 when the spacial frequency was 0.5 LP/mm, which was 2.68 times of T-grain′s, and 1.42 times of CaWO4 screen-Kodak film′s. (2) The WS values of T-grain increased when voltage go up to 90 kV from 80 kV. Conclusion　The WS value of BaFCl:Eu screen-Kodak film was largest while the WS value of T-grain was smallest, so the T-grain technique should be used.