CAJ | 학술논문

目的分析瓦里安23EX加速器附加千伏级X线锥形束CT (CBCT)在不同扫描条件下模体图像在不同位置处的CT值线性变化.方法应用安装在直线加速器上的CBCT系统在标准头(体)部扫描条件下重复扫描不同位置Catphan504模体,将结果传至计划系统及Matlab 7.0,测量不同位置处不同密度插件的CT值线性情况.经与传统扇形束CT重建后图像CT值线性结果进行比较,了解CBCT图像CT值线性空问分布.结果模体CBCT图像在标准头(体)部扫描条件下,在横断面、矢状面、冠状而及偏中心位置处CT值线性均有良好表现,其线性拟合因子R2值均＞0.953.Bowtie滤过器虽然使得被测量物质的CT值不同,但并不改变CBCT图像CT值的线性.结论瓦里安23EX加速器附加CBCT罔像CT值线性良好,如对CT值做进一步校正,使CBCT图像用于治疗计划系统的剂量计算将成为可能.
목적 분석와리안23EX가속기부가천복급X선추형속CT (CBCT)재불동소묘조건하모체도상재불동위치처적CT치선성변화.방법 응용안장재직선가속기상적CBCT계통재표준두(체)부소묘조건하중복소묘불동위치Catphan504모체,장결과전지계화계통급Matlab 7.0,측량불동위치처불동밀도삽건적CT치선성정황.경여전통선형속CT중건후도상CT치선성결과진행비교,료해CBCT도상CT치선성공문분포.결과 모체CBCT도상재표준두(체)부소묘조건하,재횡단면、시상면、관상이급편중심위치처CT치선성균유량호표현,기선성의합인자R2치균＞0.953.Bowtie려과기수연사득피측량물질적CT치불동,단병불개변CBCT도상CT치적선성.결론 와리안23EX가속기부가CBCT망상CT치선성량호,여대CT치주진일보교정,사CBCT도상용우치료계화계통적제량계산장성위가능.
Objective To investigate the CT number linearity of the cone-beam CT (CBCT) images at the different spatial locations in the scanning area.Methods The CatphanS04 phantom at the different locations are scanned repeatcdly using the CBCT on the Varian 23EX linear accelerator.The phantom is located the isocenter point,eccentric 3 cm,eccentric 6 cm,and different points on the z-axis successively on the accelerator.The scanned mode is the standard head mode.The reconstructive thickness is 2.5 cm.The different densities inserts of CTP404 module on the different locations are measured via Eclips treatment planning system (TPS) and computed by Matlab 7.0 and the CT linear fitting are then processed.In order to understand better the linear distribution along with the value of CT in the spatial distribution the results are compared with the fan-beam CT.Results Phantom studies show that:CBCT has good linearity performance not only under the standard header (body) of the scanning conditions,but also on such locations including the cross-sectional,the sagittal,the coronal plane and the eccentric position ( R2 ＞ 0.953 ).Bowtie filtration device does not change the CT finearity but changes the value of CT.Conclusions The linearity of X-ray CBCT on the Varian linear accelerator is favorable.CBCT will be used in the TPS dose calculation via further correction of the CT value.