CAJ | 학술논문

目的通过运动靶区的模拟,探讨CT扫描对运动肿瘤靶区勾画范围准确性的影响,寻找提高运动靶区准确显示的方法.方法以不同频率和振幅做简谐运动的靶区在CT机上扫描,每组分别重复扫描24次,然后对组内24次扫描图像每2、3次扫描随机分组融合.在Pinnacle计划系统中勾画靶区,分析运动对靶区沿运动方向长度的影响.结果随运动幅度增加,CT扫描所得球形靶区最大体积与方形靶区最大长度都增加,球形靶区最小体积与方形靶区最小长度减小.运动频率对靶体积及长度影响较运动幅度小.对静止扫描长度为3.3 cm、运动频率为20和幅度为2 cm的方形运动靶区24次扫描中最大长度5.1 cm是最小长度2.1 cm的2.4倍.对组内24次扫描图像每1、2、3次融合,融合后靶区长度平均值±标准差分别为(3.77±1.20)、(4.18±0.91)、(4.52±0.59)cm.结论随运动频率和幅度增加,CT扫描图像与靶区整个运动范围偏差增大.随扫描次数增加,融合所得靶区长度逐渐增加.在没有条件采取措施控制靶区运动情况下,重复CT扫描能简便有效地提高运动靶区勾画范围准确性.
목적 통과운동파구적모의,탐토CT소묘대운동종류파구구화범위준학성적영향,심조제고운동파구준학현시적방법.방법 이불동빈솔화진폭주간해운동적파구재CT궤상소묘,매조분별중복소묘24차,연후대조내24차소묘도상매2、3차소묘수궤분조융합.재Pinnacle계화계통중구화파구,분석운동대파구연운동방향장도적영향.결과 수운동폭도증가,CT소묘소득구형파구최대체적여방형파구최대장도도증가,구형파구최소체적여방형파구최소장도감소.운동빈솔대파체적급장도영향교운동폭도소.대정지소묘장도위3.3 cm、운동빈솔위20화폭도위2 cm적방형운동파구24차소묘중최대장도5.1 cm시최소장도2.1 cm적2.4배.대조내24차소묘도상매1、2、3차융합,융합후파구장도평균치±표준차분별위(3.77±1.20)、(4.18±0.91)、(4.52±0.59)cm.결론 수운동빈솔화폭도증가,CT소묘도상여파구정개운동범위편차증대.수소묘차수증가,융합소득파구장도축점증가.재몰유조건채취조시공제파구운동정황하,중복CT소묘능간편유효지제고운동파구구화범위준학성.
Objective To find a method to improve the range accuracy of moving target such as peripheral lung tumors, since a single CT snapshot may not be accurate during the treatment process.Methods A simple harmonic motion phantom, embedded with a cube and a circular ball, was used to simulate the tumor motion. Individualized moving targets were scanned 24 times with different amplitudes and frequencies. Then the images were fused from every 1, 2 or 3 sets of CT scans. The GTV volume variation of circular target and the length variation of the cube target along the z axis were contoured and analyzed. Results As motion amplitude increased, the maximum of both circular target volume and cube target length was increased, while the minimum of the factors was decreased. Motion frequency affected the target volume less than amplitude. For a cube target with the length of 3.3 cm at stationary phase, when motion frequencies was 20 and motion amplitude was 2 cm, the maximal length was 2. 4 times of the minimal length (5. 1 cm vs. 2. 1 cm). When it came to the cube target groups fused from every 1,2 and 3 sets of CT scans, the average length and standard deviation were (3.77 ± 1.20) cm, (4.18 ±0. 91)cm and (4.52 ±0. 59) cm, respectively. With the increase of fused scan number, targets became bigger, the standard deviation decreased, and the change of center positions was decreased. Conclusions The motion amplitude, frequency and the number of CT scans are the main factors affecting target definition, though, the optimized scanning phase is not certained. When 4DCT and respiration gating technique are not available,the efficient and practical method to solve this problem is to scan the target three or more times and fuse them in planning system, which will generate a larger, more reproducible GTV volume for moving targets.