Evaluation of Image Quality and Radiation Dose according to Use of the Tin Filter during CT Examination

Evaluation of Image Quality and Radiation Dose according to Use of the Tin Filter during CT Examination

CT검사 시 사용되는 주석 필터(Tin filter)는 30-50 keV 사이의 저에너지 X선을 차단함으로써, 영상의 화질을 저하하지 않고 환자 피폭을 감소시키는 효과가 있다. 본 연구에서는 흉부 팬텀을 이용하여 저선량 프로토콜 사용과 주석 필터의 사용 여부에 따른 영상의 화질 및 선량을 비교 및 평가하였다. 평가 결과 주석 필터를 사용한 CT 검사 시, 필터를 사용하지 않을 때보다 저에너지 영역을 제거함으로써 피폭선량이 큰 폭으로 감소하는 것으로 나타났으나, SNR과 CNR은 미미하게 감소하는 것으로 나타났다. 따라서 주석 필터의 사용은 영상의 품질은 유지하면서 선량의 감소를 실현함으로써, 피검자의 피폭선량 저감에 도움이 될 것으로 생각한다.

The Tin Filter used in CT scans in medical field has the effect of reducing patient exposure without deteriorating the image quality by block in low-energy X-rays (ranging 30-50 keV) generated from CT scanners. In this study, chest low-dose CT scans were performed with the lungman phantom and various low-dose scan protocol. Then, the image quality of acquired images were evaluated by comparing the radiation dose as to the use of tin filter. The performed evaluation showed that when performing CT scans with a Tin filter installed, the exposure dose was considerably reduced by removing low energy X-rays, but SNR and CNR decreased slightly. Therefore, it is significantly considered that the use of a tin filter in CT scans will help reduce the exposure dose as well as the patient dose while maintaining image quality.