中华核医学与分子影像杂志
中華覈醫學與分子影像雜誌
중화핵의학여분자영상잡지
Chinese Journal of Nuclear Medicine and Molecular Imaging
2012年
4期
294-297
,共4页
林琳%郑容%王奕斌%耿建华%吴宁%赵平
林琳%鄭容%王奕斌%耿建華%吳寧%趙平
림림%정용%왕혁빈%경건화%오저%조평
肿瘤%放射疗法%体层摄影术,发射型计算机%体层摄影术,X线计算机%靶区勾画%模型,结构
腫瘤%放射療法%體層攝影術,髮射型計算機%體層攝影術,X線計算機%靶區勾畫%模型,結構
종류%방사요법%체층섭영술,발사형계산궤%체층섭영술,X선계산궤%파구구화%모형,결구
Neoplasms%Radiotherapy%Tomography,emission-computed%Tomography,X-ray computed%Target delineation%Models,theoretical
目的 通过模型实验推导出在18F-FDG PET/CT的PET图像上确定放疗靶区边界阈值的公式.方法 向容积为9L的圆柱状模型内体积分别为0.5、1、2、4、8和16 ml的6个球体内注入浓度为203.5 MBq/L的18F-FDG,圆柱状模型其他空间注入浓度为6.179或16.021 MBq/L的18 FFDG溶液或无放射性的纯净水作为本底,形成靶/本底比值分别为32.96∶1、12.69∶1或热球零本底的3个实验条件.对各实验条件下的模型行PET/CT显像,研究球状热灶的边界阈值与热球ROI内平均放射性浓度的关系,推导出线性公式,并将其应用于勾画已知体积的热球模型,以t检验比较公式法及40％阈值法(以热球最大放射性计数的40％为热球模型边界)的勾画体积与真实体积的差异.结果 热球的边界阈值(y)与热球ROI内平均放射性浓度(x)呈线性相关:y=(x+2.6227)/1.9752.勾画热球模型时,公式法的勾画体积与真实体积的平均差值为2.83％,小于40％阈值法的平均差值3.55％,但二者之间差异无统计学意义(t=0.306,P＞0.05).体积的影响:公式法勾画热球模型时,当球体积≥1ml时,勾画体积与真实体积间的平均差值为1.01％;当球体积为0.5ml时,相应差值达9.53％.而40％阈值法勾画时,当球体积≥2 ml时,勾画体积与真实体积间的平均差值为-4.62％;但当体积为0.5及1 ml时,平均差值达19.9％.靶/本底比值的影响:公式法勾画热球模型时,当球体积≥1 ml时,3种不同的靶本底比值下勾画体积与真实体积间的平均差值分别为2.66％、1.11％和-0.74％,三者之间差异无统计学意义(t值分别为1.373、2.798和1.328,P均＞0.05);而40％阈值法勾画时,当球体积≥2ml时,随着靶本底比值的降低,勾画体积与真实体积间的平均差值逐渐减小.结论 热灶的边界阈值与热灶ROI内平均放射性浓度密切相关,由此得出的线性公式可较准确地勾画体积≥1ml的热球模型的边界.当热球体积≥1ml时,靶/本底比值对公式法勾画热球边界无明显影响.
目的 通過模型實驗推導齣在18F-FDG PET/CT的PET圖像上確定放療靶區邊界閾值的公式.方法 嚮容積為9L的圓柱狀模型內體積分彆為0.5、1、2、4、8和16 ml的6箇毬體內註入濃度為203.5 MBq/L的18F-FDG,圓柱狀模型其他空間註入濃度為6.179或16.021 MBq/L的18 FFDG溶液或無放射性的純淨水作為本底,形成靶/本底比值分彆為32.96∶1、12.69∶1或熱毬零本底的3箇實驗條件.對各實驗條件下的模型行PET/CT顯像,研究毬狀熱竈的邊界閾值與熱毬ROI內平均放射性濃度的關繫,推導齣線性公式,併將其應用于勾畫已知體積的熱毬模型,以t檢驗比較公式法及40％閾值法(以熱毬最大放射性計數的40％為熱毬模型邊界)的勾畫體積與真實體積的差異.結果 熱毬的邊界閾值(y)與熱毬ROI內平均放射性濃度(x)呈線性相關:y=(x+2.6227)/1.9752.勾畫熱毬模型時,公式法的勾畫體積與真實體積的平均差值為2.83％,小于40％閾值法的平均差值3.55％,但二者之間差異無統計學意義(t=0.306,P＞0.05).體積的影響:公式法勾畫熱毬模型時,噹毬體積≥1ml時,勾畫體積與真實體積間的平均差值為1.01％;噹毬體積為0.5ml時,相應差值達9.53％.而40％閾值法勾畫時,噹毬體積≥2 ml時,勾畫體積與真實體積間的平均差值為-4.62％;但噹體積為0.5及1 ml時,平均差值達19.9％.靶/本底比值的影響:公式法勾畫熱毬模型時,噹毬體積≥1 ml時,3種不同的靶本底比值下勾畫體積與真實體積間的平均差值分彆為2.66％、1.11％和-0.74％,三者之間差異無統計學意義(t值分彆為1.373、2.798和1.328,P均＞0.05);而40％閾值法勾畫時,噹毬體積≥2ml時,隨著靶本底比值的降低,勾畫體積與真實體積間的平均差值逐漸減小.結論 熱竈的邊界閾值與熱竈ROI內平均放射性濃度密切相關,由此得齣的線性公式可較準確地勾畫體積≥1ml的熱毬模型的邊界.噹熱毬體積≥1ml時,靶/本底比值對公式法勾畫熱毬邊界無明顯影響.
목적 통과모형실험추도출재18F-FDG PET/CT적PET도상상학정방료파구변계역치적공식.방법 향용적위9L적원주상모형내체적분별위0.5、1、2、4、8화16 ml적6개구체내주입농도위203.5 MBq/L적18F-FDG,원주상모형기타공간주입농도위6.179혹16.021 MBq/L적18 FFDG용액혹무방사성적순정수작위본저,형성파/본저비치분별위32.96∶1、12.69∶1혹열구령본저적3개실험조건.대각실험조건하적모형행PET/CT현상,연구구상열조적변계역치여열구ROI내평균방사성농도적관계,추도출선성공식,병장기응용우구화이지체적적열구모형,이t검험비교공식법급40％역치법(이열구최대방사성계수적40％위열구모형변계)적구화체적여진실체적적차이.결과 열구적변계역치(y)여열구ROI내평균방사성농도(x)정선성상관:y=(x+2.6227)/1.9752.구화열구모형시,공식법적구화체적여진실체적적평균차치위2.83％,소우40％역치법적평균차치3.55％,단이자지간차이무통계학의의(t=0.306,P＞0.05).체적적영향:공식법구화열구모형시,당구체적≥1ml시,구화체적여진실체적간적평균차치위1.01％;당구체적위0.5ml시,상응차치체9.53％.이40％역치법구화시,당구체적≥2 ml시,구화체적여진실체적간적평균차치위-4.62％;단당체적위0.5급1 ml시,평균차치체19.9％.파/본저비치적영향:공식법구화열구모형시,당구체적≥1 ml시,3충불동적파본저비치하구화체적여진실체적간적평균차치분별위2.66％、1.11％화-0.74％,삼자지간차이무통계학의의(t치분별위1.373、2.798화1.328,P균＞0.05);이40％역치법구화시,당구체적≥2ml시,수착파본저비치적강저,구화체적여진실체적간적평균차치축점감소.결론 열조적변계역치여열조ROI내평균방사성농도밀절상관,유차득출적선성공식가교준학지구화체적≥1ml적열구모형적변계.당열구체적≥1ml시,파/본저비치대공식법구화열구변계무명현영향.
Objective To propose a model-based method for calculating the threshold in GTV determination by 18 F-FDG PET in a phantom study.Methods A phantom was constructed of a 9 L cylindrical tank.Glass spheres with volumes ranging from 0.5 to 16 ml (0.5,1,2,4,8 and 16 ml) were suspended within the tank.The six spheres were filled with an identical concentration of FDG ( 203.5 MBq/L) and suspended within 3 different background baths of FDG (6.179,16.021,0 MBq/L) solutions,creating 3 target-to-background ratios of 32.96∶ 1,12.69∶1 and target to zero background.A linear regressive function was constructed which represented the relationship between the threshold and the average activity concentration of the target.A 40％ of maximum intensity threshold and the linear regressive function method were applied to define the spheres filled with 18F-FDG.The volume differences between the two methods and the true volumes of the spheres were compared with t-test.Results The linear regressive function model was derived as:threshold =(mean target concentration + 2.6227)/1.9752.The results indicated that a smaller deviation occurred when the function was utilized to estimate the volumes of the phantoms as compared to the 40％ of maximum intensity threshold method,but there were no significant differences between them ( t =0.306,P ＞ 0.05 ).The effect of the linear regressive function on volume was such that when the phantom sphere volumes were ≥ 1 ml,the average deviation between the defined volumes and the true volumes of phantoms was 1.01％ ; but when the phantom sphere volume was 0.5 ml,the average deviation was 9.53％.When the 40％ of maximum intensity threshold method was applied to define the phantom spheres of volume≥2 ml,the average deviation between the defined volumes and the true volumes of phantoms was -4.62％ ; but,the average deviation of that was 19.9％ when the volumes of spheres were 0.5 and 1 ml.When the linear regressive function was applied to phantom spheres with volume ≥ 1 ml,the effect of targetto-background ratios on volume estimation was such that the average deviation between the defined volumes and the true volumes of phantoms were 2.66％,1.11％, - 0.74％ under 3 target-to-background ratios,which showed no statistically significant differences among them (t values were 1.373,2.798,1.328,all P ＞0.05 ).When the 40％ of maximum intensity threshold method was applied to define the phantom spheres of volumes ≥2 ml,the average deviation between the defined volumes and the true volumes of phantoms decreased in parallel to the decreasing target-to-background ratios.Conclusions The threshold constructed by the linear regression function was strongly dependent on the mean target concentration,and the function can be adequately applied to estimate phantoms with volume≥ 1 ml.Target-to-background ratios had no obvious effect on the linear regressive function method when the volumes of the spheres were above 1 ml.
