摘要
目的：利用Varian-OBI系统提供的3种放射治疗位置验证模式（KV—KV、KV—MV和CBCT），分析二维位置验证方法相对于三维位置验证的差异，寻找头颈部调强放疗（IMRT）时的最佳IGRT方法和应用方式。方法：选择10例头颈部调强患者，以每周一次的频数进行治疗前位置验证，每次验证时首先行二维（KV—KV／KV—MV）位置验证，根据验证结果进行移位纠正后再用CBCT行三维验证，记录参考图像和采集图像的三个方向（Vertical，Longitudinal，Lateral）和绕三个方向的旋转（Rtn=Yaw，Roll，Pitch，）的偏移值，统计并计算均值和标准差，并记录和比较分析三种验证方式的时间等参数。结果：本研究共获取53组图像，三种验证方式在Vertical，Longitudinal，Lateral三个方向的平移偏差分别为：KV—KV：（-0．006±0．141）cm，（0．148±0．269）Cill，（-0．063±0．254）cm；KV—MV：（-0．01±0．145）cm，（0．09±0．323）cm，（-0．115±0．232）cm；CBCT：（0．04±0．12）cm，（0．06±0．12）cm，（0．00±0．1）cm。Vertical，Longitudinal，Lateral三个方向≤3mill、5mm、5mm的概率KV—KV：94％，85％，91％；KV—MV：90％，85％，95％。绝对最大值分别为：KV—KV：0．4cm，0．6cm，0．6cm；KV—MV：0．5cm．0．9cm，0．6cm。CBCT：Vertical，Longitudinal，Lateral三个方向≤2mm概率分别为：100％，94％，100％，绝对最大值为：0．2cm，0．3cm，0．2cm。三个方向旋转偏差Rtn，Roll，Pitch分别为：（-0．38±1．66）°，（0．36±1．51）°，（-0．3±0．87）°，绝对最大值为：4．3°，3．8°，2．°。≤±3。为92％，96％，100％。≤±2°为77％，8l％，96％。KV—KV、KV—MV、CBCT采集时间分别为1′20″、2′、35″，图像配准分析时间分别为〈5′、5′-8′、10′～15′。KV—KV与KV—MV两种配准模式对比分析，三个平移方向之间无统计学差异（p〉0．05）。CBCT自动配准和自动＋手动配准对比分析结果无统计学差异（p〉0．05）。结论：KV—KV与KV—MV相比，图像引导时间（包括图像采集时间和图像配准分析时间）约为KV—MV的二分之一，MV图像分辨率低，配准精度难以保证，在二维位置验证中宜优先选择KV—KV模式。KV—KV与CBCT相比，能使平移偏差减小到2mm之内，且图像引导时间约相当于CBCT的三分之一。在CBCT基准下，用KV—KV进行二维验证精度可信且时间较短，可使有限的IGRT资源得到更多的利用。
Objective： To use three radiotherapy verification of position （KV-KV,KV-MV and CBCT）from Varian-OBI syetem,analysis the difference between 2 dimensions and 3 dimensions verification,try to find the best application of IGRT for head and neck IMRT patients. Methods： 10 head and neck IMRT patients were selected ,each patient got a verification of posi- tion before treatment once a week,2D position verification（KV-KV/KV-MV）was used in the first place, shift the couch position according to the verification results,then 3D-CBCT was used, the deviation between reference image and acquisiton image in translational （Vertical, Longitudinal, Lateral） and correspond rotational orientation （Rtn=Yaw, Roll, Pitch,）were recorded, the mean and standard errors of them were calculated by statistical software, and the time and more parameters of three verification modles were recorded and compared. Results： Fifty-three image sets were collected, the mean and standard errors of three trans lational （Vertical, Longitudinal, Lateral） position deviation were KV-KV： （-0.0060.141 ）cm, （0.148±0.269） cm, （-0.063v 0.254） cm; KV-MV： （-0.01±0.145） cm, （0.09± 0.323） cm, （-0.115 ± 0.232） cm; CBCT： （0.04± 0.12） cm, （0.06±0.12） cm, （0.00± 0.14） era. KV-KV：94% ,85% ,91% ;KV-MV：90%, 85% ,95%, ≤3 mm in Vertical, ≤5 mm in Longitudinal and Lat- eral orientation, the absolute maximum were 0.4 cm, 0.6 cm and 0.6 cm. in KV-KV and 0.5cm, 0.9 cm and 0.6 cm in KV-MV. CBCT： 100 %, 94 %, 100 %, ≤3mm in Vertical, ≤ 5mm in Longitudinal and Lateral orientation, the absolute maximum were 0.2cm, 0.3 cm and 0.2 cm. the mean and standard errors of three rotational（Rm, Roll, Pitch,）deviation were （-0.38±1.66） ° , （0.36± 1.51） ° ,（-0.3±0.87）° , the absolute maximum were 4.3°,3.8° ,2.7° . 92% ,96%, 100%,≤± 3° in Rtu, Roll and Pitch orientation. 77% ,81% ,96%, ≤±2° in Rtu, Roll and Pitch orientation.the time ofacqnisiton image were：KV-KV： 1′20″,KV-MV： 2′ ,CBCT： 35″ .The time of registration were KV-KV： 〈5′ ,KV-MV： 5″ -8′ ,CBCT： 10′ -15′.No statistically signficant difference between KV-KV and KV-MV（p 〉0.05）, the two registrations of CBCT（Anto vs Auto＋Manual） had no statistically signficant difference （p 〉 0.05） .Conclusions： The total time （include the time of acquistion and registration ） of KV-KV was about half of KV-MV, MV image has low resolution,registration accuracy was difficult to guarantee,should give priority to KV-KV model in the two-dimensional position verification.compared to CBCT,KV-KV could reduce translational deviation to 2mm,and the total time of KV-KV was about one third of CBCT. The precision of KV-KV two-dimensional posi- tion verification is conceivable, and the time is short as compared to CBCT. It can make the IGRT being fully used.
出处
《中国医学物理学杂志》
CSCD
2010年第4期1988-1992,共5页
Chinese Journal of Medical Physics
关键词
头颈部调强
位置验证
锥形束CT
千伏
兆伏
比较
head and neck intensity-modulated radiotherapy
position verification.cone-beam computed tumography
kilovolt- age
megavoltage
comparion
