非小细胞肺癌靶区勾画的共识与争议

目的 分析非小细胞肺癌(NSCLC)靶区勾画过程中的专家共识与争议.方法 ①发放调杏表调查国内外12家放疗单位对NSCLC靶区勾画相关6个问题的意见.调查内容涉及摆位误差、局部晚期NSCLC 同步放化疗时原发灶和纵隔淋巴结靶区勾画、放疗中需改野的患者比例和时机、早期肺癌放疗的单次剂最、早期肺癌大剂量放疗时靶区勾画;②把1例局部晚期NSCLC患者的PET.CT资料寄给在京7个单位放疗科,各放疗科自行组织讨论并委1托位医师在北京地区2007放疗年会上主讲埘该例靶区勾画的理论认识和实际勾画情况,京、津、冀、辽、蒙参会专家共同讨论.结果 参与调查的12个单位全部寄回调查表.摆位误差:12个单位是5～7 mm;对于局部晚期NSCLC同步合并近标准化疗剂量的放疗:11个单位认为肺内原发灶靶区勾画PTV=GTV+6～8 mm(CTV)+摆位误差和呼吸动度,1个单位认为PTV=GTV+摆位误差和呼吸动度;对于局部晚期NSCLC同步合并近标准剂量化疗的放疗纵隔淋巴结靶区勾画,9个单位认为PTV=GTV+6～8 mm(CTV)+摆位误差和呼吸动度,3个单位认为PTV=kGTV+摆位误差和呼吸动度;对于局部晚期NSCLC同步合并近标准剂量化疗的放疗过程中约有30%的患者需要改野;11个单位开展早期肺癌大剂量放疗工作.单次剂量为5～20 Gy不等;6个单位认为早期NSCLC原发灶靶区勾画PTV=GTV+6～8 mm(CTV)+摆位误差和呼吸动度,5个单位认为PTV=GTV+呼吸动度+摆位误差.靶区勾画病例讨论中得了出的结果是:肺痛靶区勾画前应采用四维CT或模拟机测定呼吸动度;勾画肺癌靶区时CT肺窗窗宽窗位分别为1600、-600 HU,纵隔窗窗宽窗位分别为400、20 HU;争议主要是纵隔转移淋巴结CTV为GTV+6～8 mm患者还是包括所在区乃至气管食管沟?结论 NSCLC靶区/厶J画的基本共识是:①勾画前廊明确肿块的呼吸动度;②肺癌原发灶的PTV为GTV+6～8 mm+呼吸动度+摆位误差,纵隔淋巴结的PTV为GTV+6 mm+呼吸动度+摆位误差,医生可根据靶区周围正常结构情况适当修改;③肺癌摆位误差在3～9 mm,各单位应建立自己的摆位误差数据席,确定由ITV到PTV的外放距离;④无转移淋巴结区无需预放照射.主要争议是:①同步放化疗时纵隔淋巴结靶区,甚至原发灶靶区PTV是否可以为GTV+呼吸动度+摆位误差?②纵隔转移淋巴结CTV足GTV+6 mm还是需要包括所在区?③早期肺癌大剂量放疗的最佳单次剂量是多少?早期肺癌大剂最放疗PIV靶区为GTV+6～8mm+呼吸动度+摆位误差还是GTV+呼吸动度+摆位误差?     

胸上段食管癌调强放疗摆位误差及靶区外扩距离研究

目的 应用千伏级锥形束CT测量胸上段食管癌患者放疗摆位误差并估测临床靶体积至计划靶体积(CTV→PTV)外扩距离。方法 选择2010—2012年间13例胸上段食管癌患者的调强放疗计划CT图像,将图上CTV外扩形成内靶体积(ITV),再将ITV逐步1 mm/次外扩10次,每例患者均形成10个大小不一的PTV。根据这些PTV制定计划并模拟摆位误差。找到一合适PTV,使在有摆位误差时仍能保证95%ITV达到处方剂量,从而得到CTV→PTV外扩距离。结果 摆位误差在上下方向上最大,为(3.42±2.19) mm。通过PTV外扩法测得ITV→PTV的外扩范围为5 mm。根据PTV外扩法所得外扩距离制定的新计划与原计划相比双肺V₅、脊髓D_1cm³ 分别增加0.87%、4.95 Gy,心脏V₄₀、PTV D₉₅、PTV V₁₀₀、ITV D₉₅、ITV V₁₀₀分别减少0.62%、4.95 Gy、8.38%、1.84 Gy、1.87%。     

MRI定位对乳腺癌保乳术后部分乳腺照射的靶区和剂量的影响

目的 比较乳腺癌保乳术后仰卧位CT与MRI定位图像的靶区和剂量的差异,探讨MRI定位在保乳术后部分乳腺照射中的应用价值。方法 29例早期乳腺癌患者保乳术后放疗前在仰卧位下行CT及MRI定位扫描,分别对CT与MRI图像上的瘤床进行术腔可视化评分(CVS),勾画瘤床(TB)、临床靶区(CTV)、计划靶区(PTV),并基于CT图像制定部分乳腺照射计划。比较CT与MRI图像上TB的CVS、靶区差异与一致性,探讨40Gy处方剂量等剂量线覆盖PTV比例差异。结果 CT、MRI图像上TB的CVS分别为2.97±1.40、3.10±1.40(P=0.408)。MRI图像上勾画的TB、CTV、PTV较CT均明显增加,分别为(24.48±16.60) cm³∶(38.00±19.77) cm³、(126.76±56.81) cm³∶(168.42±70.54) cm³、(216.63±81.99) cm³∶(279.24±101.55) cm³(均P<0.001),但CTV、PTV增加的比例较TB明显减小(均P<0.001)。CT与MRI图像勾画的TB、CTV、PTV一致性指数分别为0.43±0.13、0.66±0.11、0.70±0.09(P<0.001)。放疗计划40Gy等剂量线覆盖PTV-CT与PTV-MRI比例中位数分别为95.6%(95.0%~97.5%)与81.9%(62.3%~92.4%)(P<0.001)。结论 CT与MRI对于TB术腔的可视化相近,但MRI图像勾画的TB、CTV、PTV范围明显增加,基于CT图像制定的放疗计划对于PTV-MRI剂量覆盖不充分。作为CT定位的补充,保乳术后MRI定位的应用可能可以提高TB勾画的准确性。     

容积调强弧形治疗与质子调强放疗在室性心动过速放射消融中的计划对比研究

目的 模拟室性心动过速(VT)患者行立体定向消融体部放疗,探索质子调强放疗(IMPT)的剂量学优势。方法 对资料完整的5例患者的胸部定位CT图像均分别勾画左心室的心尖部、心前壁、间隔壁、下壁、外侧壁心肌全层共25个大体靶体积(GTV)。GTV三维外扩5 mm为ITV,ITV外扩3 mm为PTV。每个靶区均分别设计容积调强弧形治疗(VMAT)与IMPT计划。处方剂量为单次25 Gy (RBE)。比较两种计划靶区及危及器官剂量参数。结果 中位ITV体积45.40cm³(26.72~67.59 cm³),所有计划均达到足够的靶区覆盖(ITV V95%Rx≥99%)。相比VMAT计划,IMPT组全心、心包及靶区外心脏组织Dmean分别降低44.52%、44.91%、60.16%,左前降支D0.03 cm³降低17.58%(P<0.05)。按病灶部位分析后发现,IMPT仍可降低绝大多数危及器官剂量,但当病灶位于前壁及心尖时左前降支D0.03 cm³两者相近,病灶位于前壁或下壁时左回旋支D0.03 cm³也相近(P>0.05)。结论 模拟VT患者立体定向消融体部放疗时,VMAT与IMPT计划均满足临床剂量学要求;而IMPT可降低正常心脏组织受量,具有降低缺血性心脏病、心包炎或心包积液等并发症的潜在获益。     

山东省肿瘤医院非小细胞肺癌放疗靶区勾画的研究

随着精确放疗技术在非小细胞肺癌(NSCLC)中的广泛临床应用,靶区的精确勾画和精确投照已成为影响放疗进展的瓶颈.ICRU 50号和62号报告明确规定了GTV、CTV、ITV和PTV的概念.这些概念在放疗计划特别是3DCRT及IM-RT中得到了广泛认可和应用.2000年美国纪念癌症中心Ling教授又提出生物靶区(BTV)概念.针对NSCLC放疗靶区勾画问题,结合笔者医院研究工作和相关文献归结如下.     

基于3D-CT和4D-CT的肺癌放射治疗靶区勾画方法的研究

摘 要：［目的］ 以3D-CT和4D-CT模拟定位，比较非小细胞肺癌放疗靶区的不同勾画方法。［方法］ 患者处于平静呼吸状态，依次做3D-CT扫描、4D-CT扫描，然后根据采集到的图像，按下列不同方式勾画出内靶区（ITV）：①将4D-CT构建的10个呼吸相中的肿瘤靶区（GTV）全部勾画，然后融合至全10相形成ITV10相；②以4D-CT的0%和50%相作为2个极限呼吸相，分别勾画GTV再融合至0~50相，形成ITV2相；③构建4D-CT的最高密度投影（MIP）图像，直接在MIP图像勾画ITVMIP；④在4D-CT图像上，测量头-脚、腹-背和左-右方向GTV的位移，计算95%位移值，用于3D-CT的GTV的外放依据，形成ITV3DCT。上述4种ITV，再在三维方向扩大5mm的处理，得到与之相对应的计划靶区（PTV）。从几何容积和形状匹配度两方面对上述4种ITV和PTV进行对比。［结果］ 在头-脚、腹-背、左-右方向上，GTV的位移值分别为（3.2±4.1）mm、（2.1±3.0）mm、（0.7±0.7）mm。两两比对提示，肿瘤的位移更多体现在头-脚和腹-背方向（P值均＜0.0001）。基于此数据，以GTV3DCT的头-脚、腹-背、左-右三个方向进行外放5mm、3mm、1mm生成ITV3DCT。ITV10相、ITV2相、ITVMIP、ITV3DCT中位容积分别为12.98cm3、11.55cm3、12.95cm3、16.54cm3，PTV10相、PTV2相、PTVMIP、PTV3DCT中位容积分别为31.22cm3、28.64cm3、31.18cm3、37.51cm3。与ITV10相和PTV10相比较，ITV2相、ITVMIP、ITV3DCT和PTV2相、PTVMIP和PTV3DCT的MI均值分别为0.83、0.95、0.7和0.88、0.94和0.74。［结论］ ITVMIP和PTVMIP与ITV10相和PTV10相的差距最小，合适病例可用MIP勾画靶区以保证精准、提高效率。由于容积差异较大、匹配度较低，不建议用ITV2相或ITV3DCT直接替代ITV10相设计计划。     

3D-CT勾画的食管胃结合部癌放疗疗程中靶区体积和位移变化研究

目的 三维适形放疗过程中靶区各方向的位移差异很大,有关食管胃结合部癌适形放射治疗过程中靶区位移的研究较少.本研究基于三维CT(three dimensional computed tomography,3D-CT)探讨食管胃结合部癌三维适形放疗(three dimensional conformal radiotherapy,3D-CRT)疗程中靶区位移和体积变化.方法 选取2014-01-01-2015-12-31山东大学附属山东省肿瘤医院行3D-CRT的20例食管胃结合部癌患者,基于放疗前3D-CT定位图像勾画原发肿瘤大体肿瘤体积(gross tumor volume,GTV)并定义为GTV1,基于GTV1构建相对应的临床靶区体积(clinical target vol-ume,CTV)和计划靶区体积(planning target volume,PTV)并分别定义为CTV1和PTV1;放疗至15～20次时重复定位,基于复位3D-CT扫描图像勾画GTV并定义为GTV2,构建CTV2和PTV2.比较初次和重复定位GTV体积变化和中心位移,计算初次和重复定位靶区间包含度(degree of inclusion,DI)和匹配指数(matching index,MI).结果 GTV靶区中心位移中位数分别为X轴1.7 mm,y轴2.5 mm,Z轴3.0mm,但是3个方向位移差异无统计学意义,P=0.142;GTV1和GTV2间MI1、PTV1和PTV2间MI2分别为51.75％和69.39％;GTV2对GTV1的DI1、PTV2对PTV1的DI2分别为81.49％和84.33％;GTV2较GTV1体积缩小平均15.98 cm3,体积回缩率为25.26％.PTV、GTV的MI和DI与GTV几何中心在X、y、Z轴的位移成负相关,相关性最强的是GTV DI、MI与GTV几何中心在X、Z轴上的位移.GTV靶区中心在X、y、Z轴上的位移,在临床分型之间差异无统计学意义,GTV靶区中心在X轴的位移在3种病理类型之间差异有统计学意义,P=0.027.结论 在放疗过程中,食管胃结合部癌的体积变化和靶区中心位移是明显的,因此有必要重复定位以重新勾画靶区,保证放疗计划的合理性,减少脱靶体积及不必要正常组织照射.     

部分乳腺外照射自主呼吸控制不同呼吸状态靶区体积重合度的研究

目的 探讨保乳术后部分乳腺外照射(EB-PBI)自主呼吸控制(ABC)不同呼吸状态体积重合度及其差异,从靶区体积重合的角度,表述ABC辅助呼吸运动对EB-PBI分次内靶区位移的影响.方法 对术腔放置银夹拟行EB-PBI的患者行乳腺托架固定ABC辅助CT模拟定位,同时采集适度深吸气呼吸控制(mDIBH)状态、自由呼吸(FB)状态、深吸气呼吸控制(DEBH)状态各2套CT图像.应用Pinnacle3治疗计划系统,进行2套mDIBH图像间、2套FB图像间、2套DEBH图像间及mDIBH与DEBH图像间自动融合,计算融合图像.选定进行融合的2套图像的大体肿瘤体积(GTV)、临床靶区体积(CTV)、计划靶区体积(PTV)的重合度,比较同一配准中3种靶区各自重合度间及不同配准中同一种靶区重合度间的差异.结果 mDIBH/mDIBH配准中,GTV/GTV、CTV/CTV和PTV/PTV重合度分别为(83.54±11.41)%、(93.00±6.49)%和(95.26±4.90)%,GTV/GTV与CTV/CTV、GTV/GTV与PTV/PTV重合度间差异均有统计学意义(P＜0.05),而CTV/CTV与PTV/PTV重合度间差异无统计学意义(P＞0.05).FB/FB配准中,GTV/GTV、CTV/CTV、PTV/PTV重合度分别为(72.55±29.10)%、(89.36±9.53)%和(92.47±7.25)%,GTV/GTV与CTV/CTV、CTV/CTV与PTV/PTV重合度间差异均无统计学意义(均P＞0.05),而GTV/GTV与PTV/PTV重合度间差异有统计学意义(P＜0.05).DEBH/DEBH配准中,GTV/GTV、CTV/CTV、PTV/PTV重合度分别为(79.48±22.31)%、(92.83±6.77)%和(95.05±4.81)%,3组靶区两两间重合度差异均有统计学意义(均P＜0.05).mDIBH/mDIBH与DEBH/DEBH间、mDIBH/mDIBH与FB/FB间、FB/FB与DEBH/DEBH间的GTV、CTV和PTV重合度差异均无统计学意义(均P＞0.05),而mDIBH/mDIBH与mDIBH/DEBH间、FB/FB与mDIBH/DEBH间的GTV、CTV和PTV重合度差异均有统计学意义(均P＜0.05).结论 ABC辅助实施EB-PBI,两次mDIBH间、两次FB间和两次DEBH间各靶区体积重合度差异不明显,且三者的PTV/PTV重合度均达到较高水平.因此,从靶区重合度的角度,若施照前进行在线摆位误差校正,EB-PBI实施进行呼吸控制的必要性值得商榷.     

肢体软组织肉瘤术后放疗缩小放疗野的临床观察

目的 探讨肢体软组织肉瘤术后缩小放疗野放疗的效果,重点观察局部控制率和不良反应发生情况。方法 回顾性分析2017年10月至2021年3月清华大学第一附属医院收治的49例肢体软组织肉瘤患者,所有患者术后均接受调强放疗。采用定位CT和术后MRI图像融合的方法进行靶区勾画,定义瘤床（GTV_tb）在纵轴方向外扩3 cm,横轴方向外扩1.5 cm形成临床靶区（CTV,解剖屏障可适当修回,且需包全肿瘤周围水肿区）。GTV_tb和CTV分别外扩0.5 cm形成计划靶区1（PTV1）和PTV2,放疗处方剂量：PTV1_95%为63~66 Gy,PTV2_95%为50~56 Gy,单次1.8~2.0 Gy。若术后镜下切缘阳性,瘤床区域推量至70 Gy。结果 随访7.9~45.6个月,中位随访时间32.1个月。3年无局部失败生存率、总生存率和无远处转移生存率分别为91.7%、77.6%、71.5%。单因素分析结果显示,术后镜下切缘阳性的患者更容易出现局部复发,P<0.05。2级及以上伤口并发症、关节僵硬、骨折、水肿、皮肤纤维化的发生率分别为2%、4.1%、2%、8.2%、26.5%。结论 术后放疗缩小放射野治疗肢体软组织肉瘤得到了较好的局部控制率,且晚期不良反应发生率较低。     

原发肿瘤体积对IV期非小细胞肺癌生存影响——来自多中心Ⅱ期前瞻性临床研究结果再分析

目的 探讨Ⅳ期非小细胞肺癌(NSCLC)原发肿瘤三维放疗的原发肿瘤体积对生存的影响。方法 2002-2017年一项多中心前瞻性临床研究再分析入组患者428例,可生存分析423例。化疗以铂类为基础的二药联合方案,中位化疗4个周期,PTV分界值63Gy,GTV分界值150cm³。结果 Cox模型预后分析发现女性、治疗后KPS评分、单器官转移、N0-N1期、腺癌、放疗≥63Gy、4~6个周期化疗、近期有效、治疗后进展服用靶向药物、GTV体积<150cm³是良好预后因素(P均<0.05)。根据不同化放疗方案分层分析发现GTV体积≥150cm³全身化疗基础上联合原发肿瘤放疗剂量≥63Gy生存优于放疗剂量<63Gy (P<0.05)。结论 Ⅳ期NSCLC患者GTV体积≥150cm³,行4~6个周期化疗联合PTV放疗≥63 Gy和GTV体积<150cm³ ,行1~3个周期化疗联合PTV放疗≥63Gy也许延长Ⅳ期NSCLC患者总生存。     

Analyse des contraintes dosimétriques obtenues par trois techniques d’irradiation de tumeurs pulmonaires

PurposeComparison of three dosimetric techniques of lung tumor delineation to integrate tumor motion during breathing.Patients and methodsNineteen patients with T1-3N0M0 malignant lung tumor were treated with definitive chemoradiotherapy (14 cases) or pre-surgery chemoradiation. Doses were, respectively, 66 and 46 Gy. CT-scan for delineation was performed during three phases of breathing: free breathing and deep breath-hold inspiration and expiration. GTV (gross tumor volume) was delineated on the three sequences. The classic technique included GTV from the free-breathing sequence plus a CTV (clinical target volume) margin of 5 to 8 mm plus a PTV (planning target volume) margin of 7 to 10 mm (including ITV [internal target volume] margin and set-up margin). The gating-like technique included GTV from the deep breath-hold inspiration sequence plus a CTV margin of 5 to 8 mm plus a PTV margin of 2 mm. The three-volume technique, included GTV as a result of the fusion of GTVs from the three sequences plus a CTV margin of 5 to 8 mm plus a PTV margin of 2 mm. Dosimetry was calculated for the three PTVs, if possible, with the same fields number and position. Dose constraints and rules were imposed to accept dosimetries: firstly spinal cord maximal dose less than 45 Gy, followed by V95 % for PTV greater than or equal to 95 %, and V20 GY_Gy for lung less than or equal to 30 %, V30 GY_Gy for lung less than or equal to 20 %.ResultsGTVs were not statistically different between the three methods of delineation. PTVs were significantly lower with the gating-like technique. V95% of the PTV were not different between the three techniques. With the classic-, the gating-like- and the 3-volume techniques, dosimetry was considered as acceptable, respectively in 15, 18 and 15 cases. Comparisons of constraint values showed that the gating-like method gave the best results. In the case of pre-operative management, the gating-like method allowed the best results even for the V95% values. However, in the absence of gating device or without the possibility to use it, the 3-volume method allowed to take into account more precisely the organ motion than the classical technique.ConclusionThe 3-volume method can be done. It is a good method to take into account the organ motions. However, the gating-like method gives the best results leading to propose its use even for pre-operative patients with upper tumors.     

The effect of breathing and set-up errors on the cumulative dose to a lung tumor.

BACKGROUND AND PURPOSE: To assess the impact of both set-up errors and respiration-induced tumor motion on the cumulative dose delivered to a clinical target volume (CTV) in lung, for an irradiation based on current clinically applied field sizes. MATERIALS AND METHODS: A cork phantom, having a 50 mm spherically shaped polystyrene insertion to simulate a gross tumor volume (GTV) located centrally in a lung was irradiated with two parallel opposed beams. The planned 95% isodose surface was conformed to the planning target volume (PTV) using a multi leaf collimator. The resulting margin between the CTV and the field edge was 16 mm in beam's eye view. A dose of 70 Gy was prescribed. Dose area histograms (DAHs) of the central plane of the CTV (GTV+5 mm) were determined using radiographic film for different combinations of set-up errors and respiration-induced tumor motion. The DAHs were evaluated using the population averaged tumor control probability (TCP(pop)) and the equivalent uniform dose (EUD) model. RESULTS: Compared with dose volume histograms of the entire CTV, DAHs overestimate the impact of tumor motion on tumor control. Due to the choice of field sizes a large part of the PTV will receive a too low dose resulting in an EUD of the central plane of the CTV of 68.9 Gy for the static case. The EUD drops to 68.2, 66.1 and 51.1 Gy for systematic set-up errors of 5, 10 and 15 mm, respectively. For random set-up errors of 5, 10 and 15 mm (1 SD), the EUD decreases to 68.7, 67.4 and 64.9 Gy, respectively. For similar amplitudes of respiration-induced motion, the EUD decreases to 68.8, 68.5 and 67.7 Gy, respectively. For a clinically relevant scenario of 7.5 mm systematic set-up error, 3 mm random set-up error and 5 mm amplitude of breathing motion, the EUD is 66.7 Gy. This corresponds with a tumor control probability TCP(pop) of 41.7%, compared with 50.0% for homogeneous irradiation of the CTV to 70 Gy. CONCLUSION: Systematic set-up errors have a dominant effect on the cumulative dose to the CTV. The effect of breathing motion and random set-up errors is smaller. Therefore the gain of controlling breathing motion during irradiation is expected to be small and efforts should rather focus on minimizing systematic errors. For the current clinically applied field sizes and a clinically relevant combination of set-up errors and breathing motion, the EUD of the central plane of the CTV is reduced by 3.3 Gy, at maximum, relative to homogeneous irradiation of the CTV to 70 Gy, for our worst case scenario.     

Set-Up Errors,Organ Motion,Tumour Regression and its Implications on Internal Target Volume–Planning Target Volume During Cervical Cancer Radiotherapy: Results From a Prospective Study

AimsUterocervical motions and organ filling during cervical cancer conformal radiotherapy is complex. This prospective, observational study investigated set-up margins (clinical target vo, ume [CTV] to planning target volume [PTV]) for pelvic nodal CTV and internal margin (CTV to internal target volume [ITV]) expansions for uterocervical movements during cervical cancer radiotherapy.Materials and methodsDuring cervical cancer radiotherapy, a daily kilovoltage, cone-beam computed tomography (CBCT) scan was acquired. Bony anatomy-based rigid co-registration and matching to vessels/pelvic nodal region was carried out to document shifts, errors (systematic and random) and to calculate CTV to PTV margins. Subsequently, soft-tissue matching was carried out at the mid-cervical region and uterine fundus to record shifts, errors and to calculate CTV to ITV margins.ResultsIn 67 patients, 1380 CBCT scans were analysed. The mean (±standard deviation) couch shifts for CTV pelvic nodal region in all directions were within 4.5–5.3 mm, systematic and random errors 3.0–3.6 mm and set-up margins of within 10 mm (except anterior margin 10.3 mm). For the mid-cervical region, mean shifts were 4.5–5.5 mm, systematic and random errors 2–4 mm amounting to <10 mm internal margins (CTV–ITV for cervix) and for uterine fundus mean (±standard deviation) shifts were larger in the superior direction (12.1 mm) but 4.0–7.5 mm in other directions, systematic and random errors 2–7 mm amounting to anisotropic margins in various directions (10 mm in anterior–posterior and lateral directions, 12–20 mm in superior–inferior directions) (CTV–ITV for uterine fundus).ConclusionOur study suggests anisotropic CTV to ITV and CTV to PTV margins for cervical cancer radiotherapy.     

肝细胞癌放疗靶区勾画的研究进展

CT、MRI、PET-CT等现代影像学设备使肝细胞癌GTV的精确勾画成为可能,通过比较术后病理亚临床病灶、影像及临床指标等有助于CTV精确勾画,放疗辅助技术(如4DCT、腹部压迫、自主呼吸控制和呼吸门控等)可缩小ITV。真空袋和体膜固定可减小摆位误差,减小PTV和避免或减少照射误差。通过这些方法使肝细胞癌放射治疗的靶区缩小、剂量提升和并发症降低得以实现。本文就肝细胞癌外照射放射治疗靶区的研究进展作一综述。     

应用千伏锥形束CT个体化确定肺癌放疗内 在靶体积的研究

 目的分析个体化确定肺癌放疗ITV的必要性和应用千伏锥形束CT（kVCBCT）个体化确定肺癌放疗ITV 的可行性。方法选择14例周围型肺癌患者进入研究。每位患者行1次常规定位CT扫描和3次kVCBCT扫描。根 据常规定位CT勾画的可见肿瘤病灶为GTV,以GTV为基础,根据肿瘤所在肺叶的位置,外扩固定边界形成 IGTV,称之为IGTV-p;根据kVCBCT勾画的可见肿瘤形成IGTV-c。GTV、IGTV-p和IGTV-c分别外扩5 mm,形 成CTV、ITV-p和ITV-c。比较ITV-p和ITV-c的体积;ITV-p叠ITV-c体积;比较CTV和ITV-c的体积;以 COM/SUM比值为参数,评价kVCBCT确定ITV的重复性。结果患者ITV-p和ITV-c的体积分别为（150.1±87.3 ） cc与（88.0±54.3） cc,二者比较,差异有明显统计学意义（P<0.0001）。ITV-p叠ITV-c体积为 （67.1±32.4） cc。CTV与ITV-c比较,二者差异具有统计学意义（P=0.005）;COM/SUM比值为（63.0± 8.2）%。结论根据常规定位CT,“群体化”确定肺癌放疗ITV存在不足,锥形束CT可以用于个体化确定肺 癌放疗的ITV。     

Excluding either gross tumor volume or planning target volume from the normal lung volume in lung cancer irradiation: Evaluation of the dosimetric impact

PurposeWhen evaluating dosimetric parameters predictive of lung toxicity in lung cancer, the total lung volume can be defined to exclude the gross tumor volume (lung-GTV) or to exclude the planning target volume (lung-PTV). The purpose of the study was to evaluate the impact of these 2 types of delineation on the dosimetric parameters V20, V30, and mean lung dose (MLD).Methods and MaterialsWe analyzed 69 patients with lung cancer treated with 3-dimensional radiation therapy. Normal lung volume was defined using 2 modalities of delineation: lung-GTV and lung-PTV. The lung volume inside the PTV, but outside the GTV, corresponded to the margins within the lung parenchyma applied to the GTV and the clinical target volume (CTV) to obtain the PTV. This volume (expressed in percentage of total lung volume) increases with the following: (1) the margins (GTV to CTV and CTV to PTV) increase within the lung parenchyma; (2) the GTV increases; and (3) the total lung volume decreases.ResultsMean reduction of lung volume was 5.1% (range, 1.4-10.0). With the delineation lung-PTV rather than lung-GTV, the mean reduction was 3.1% (P < 10^- 7), 3.3% (P < 10^- 7), and 2.1 Gy (P < 10^- 7) for V20, V30, and MLD, respectively. These reductions correlated strongly with reduction of lung volume (r² range, 0.89-0.96). For 25% of patients having greater reduction of lung volume (high margins, high tumor volume, small lung volume), reduction of V20 ranged from 4.5%-6.3%, reduction of V30 ranged from 4.6%-7.0%, and reduction of MLD ranged from 2.9 Gy-4 Gy.ConclusionsThe dosimetric parameters V20, V30, and MLD are reduced with the delineation using lung-PTV rather than lung-GTV. These reductions correlate with lung volume in the PTV and can be significant.     

PET/CT下非小细胞肺癌三维适形放疗中肿瘤退缩及对治疗计划参数的影响

目的:观察PET/CT下非小细胞肺癌(NSCLC)三维适形放疗(3D-CRT)中肿瘤退缩对靶区周围危及器官治疗计划参数的影响.方法:分析在PET/CT定位下行根治性3D-CRT的NSCLC患者55例,根据PET/CT融合图像勾画初始肿瘤放疗靶区,给予根治剂量处方量60~66 Gy/30~33 f 制定3D-CRT计划;放疗20次40 Gy时根据肿瘤退缩情况重新CT定位勾画靶区,修改照射野后重新制定放疗计划完成治疗.比较两次定位影像上GTV的体积VGTV(cm3)、PTV的体积VPTV(cm3) 差异;并对初始放疗计划和实际完成的计划靶区周围危及器官的剂量分布进行比较.结果:55例NSCLC患者中,除1例GTV体积增大(1.77cm3,4%)外,其余54例GTV体积均有不同程度缩小(6%~67%),差异有统计学意义(t=6.635,P=0.000).相应的,除1例PTV体积增大(17.13cm3,8%)外,其余54例PTV体积均有不同程度缩小(3%~59%),差异有统计学意义(t=8.045,P=0.000).两种计划参数VGTV、VPTV、VL20、VR20、SCM、MSD、MLD、MRD、MHD、ESM差异有统计学意义(P=0.000、0.000、0.000、0.000、0.001、0.000、0.000、0.000、0.002、0.031).结论:在NSCLC放疗过程中,肿瘤体积发生明显变化,而根据肿瘤退缩情况适时缩野、重新制定放疗计划,可显著降低肺及脊髓的受照射剂量,为提高靶区剂量、优化放疗计划提供了可能.