胸上段食管癌断层定野与断层螺旋放疗和容积旋转调强放疗的剂量学比较

目的 比较胸上段食管癌断层定野放疗（TD）、断层螺旋放疗（HT）和容积旋转调强放疗（VMAT）的剂量学差异,为临床上食管癌放疗方式的选择提供依据。方法 选取15例临床分期为cT_2~4N_0~1M₀的胸上段食管癌患者,分别设计TD、HT和VMAT 3种计划。比较靶区的剂量体积直方图（DVH）、均匀指数（HI）、适形指数（CI）、危及器官（OAR）受量、治疗时间和机器跳数（MU）的差异。结果 HT和TD计划的D₂和D_mean均明显低于VMAT计划;TD计划的D₉₈和HT相似,但均高于VMAT计划。对于HI,HT < TD < VMAT,3组之间差异有统计学意义（F=81.603,P < 0.05）。3组计划的CI差异无统计学意义（P>0.05）。双肺的V₁₅,HT明显高于VMAT和TD （t=3.547、-2.626,P < 0.05）。TD计划的V₂₀与HT计划的相似,但高于VMAT计划（t=2.824、3.052, P < 0.05）。3组计划中的脊髓D_max无明显差异。HT和TD的执行时间、MU均高于VMAT,差异具有统计学意义（t=21.617、15.693、10.018、7.802,P < 0.05）。结论 与VMAT相比,HT和TD计划可明显改善胸上段食管癌靶区的剂量分布,可获得更好的适形度。但VMAT比HT或TD明显降低双肺V₂₀、MU及治疗时间。TD与HT相比,HT的靶区剂量分布更好,但TD降低了双肺的V₁₅,且缩短治疗时间。     

螺旋断层固定野调强放疗技术在中段食管癌放疗中的应用

目的 探究螺旋断层固定野调强放疗TomoDirect(TD)技术在中段食管癌放疗中的应用,并评价计划质量和效率。方法 对本院收治的10例局部晚期根治性中段食管癌患者进行研究。分别在TomoTherapy和Pinnacle³计划系统设计TD、螺旋断层调强放疗(HT)和常规加速器固定野调强放疗(IMRT)计划。比较3种计划的靶区适形度指数(CI)、均匀性指数(HI)和危及器官(OARs)受量以评价计划质量;比较治疗时间和机器跳数(MU)以评价治疗效率。结果 与IMRT计划相比,TD和HT计划的靶区CI和HI具有剂量学优势(t=5.261、10.419、-5.463、-6.862,P<0.05);与HT计划相比,TD计划的靶区CI和HI要差(t=-7.055、2.325,P<0.05)。与IMRT计划相比,TD和HT计划的平均双肺V₂₀、V₃₀和平均剂量显著变低(t=-5.372、-6.296、-5.372、-6.296、-2.865、-4.632,P<0.05)。与HT计划相比,TD和IMRT计划的心脏平均剂量要低(t=-3.112、2.829,P<0.05)、心脏最大剂量要高(t=3.154、-3.348,P<0.05)。与HT计划相比,TD计划的脊髓最大剂量和正常组织平均剂量要高(t=3.071、5.076,P<0.05)。与HT计划相比,TD平均治疗时间和机器跳数减少12.0%和37.2%(t=-4.095、-12.559,P<0.05),IMRT计划的治疗时间最短。结论 TD技术应用于中段食管癌放疗具有一定优势,与HT技术相比,TD射线利用率高,治疗时间短;与IMRT技术相比,TD靶区CI、HI以及平均双肺V₂₀、V₃₀和平均剂量具有明显的剂量学优势。     

胸上段食管癌螺旋断层放疗和容积旋转调强放疗的剂量学比较

目的 比较胸上段食管癌螺旋断层(HT)与容积旋转调强放疗(VMAT)计划的剂量学差异。方法 随机抽样法选取10例胸上段食管癌患者,分别设计HT和VMAT双弧照射调强放疗计划,肿瘤靶区体积(GTV)给予66 Gy/30次,计划靶区体积(PTV)给予50 Gy/30次。根据剂量体积直方图(DVH)评价靶区的D_1%、D_5%、D_95%、D_99%、适形指数(CI)、均匀性指数(HI)和危及器官(OAR)受量,比较治疗时间和机器跳数(MU)的差异。结果 HT组GTV和PTV的D_99%高于VMAT组(t=4.476、3.756,P<0.05);GTV与PTV的D_1%、D_5%、D_95%、HI和CI差异均无统计学意义(P>0.05)。HT组全肺V₁₀、V₁₅、V₂₀和全肺平均剂量(MLD)均显著低于VMAT组(t=-3.369、-4.824、-4.869、-3.657,P<0.05);全肺V₅、V₃₀和脊髓D_max差异均无统计学意义(P >0.05)。HT组治疗时间和MU数均远大于VMAT组(t=13.970、7.982,P<0.05)。结论 HT与VMAT技术均能满足胸上段食管癌放疗剂量要求。HT技术能显著减小双肺受量,而VMAT技术具备明显的效率优势。     

内镜下钛夹标记在食管癌三维适形放疗靶区勾画中的应用

目的 比较胸上段食管癌螺旋断层(HT)与容积旋转调强放疗(VMAT)计划的剂量学差异。方法 随机抽样法选取10例胸上段食管癌患者,分别设计HT和VMAT双弧照射调强放疗计划,肿瘤靶区体积(GTV)给予66 Gy/30次,计划靶区体积(PTV)给予50 Gy/30次。根据剂量体积直方图(DVH)评价靶区的D_1%、D_99%、D_5%、D_95%、适形指数(CI)、均匀性指数(HI)和危及器官(OAR)受量,比较治疗时间和机器跳数(MU)的差异。结果 HT组GTV和PTV的D_99%高于VMAT组(t=4.476、3.756,P<0.05);GTV与PTV的D_1%、D_5%、D_95%、HI和CI差异均无统计学意义(P>0.05)。HT组全肺V₁₀、V₁₅、V₂₀和全肺平均剂量(MLD)均显著低于VMAT组(t=-3.369、-4.824、-4.869、-3.657,P<0.05);全肺V₅、V₃₀和脊髓D_max差异均无统计学意义(P >0.05)。HT组治疗时间和MU数均远大于VMAT组(t=13.970、7.982,P<0.05)。结论 HT与VMAT技术均能满足胸上段食管癌放疗剂量要求。HT技术能显著减小双肺受量,而VMAT技术具备明显的效率优势。     

螺旋断层固定野和旋转调强放疗技术在全身照射中的应用对比研究

目的 探究使用螺旋断层固定野调强（TD）和螺旋断层旋转调强（HT）放射治疗技术在全身照射（TBI）中的应用对比,并评估TD治疗技术下计划的质量和执行效率,指导临床选择最佳的计划设计方案。方法 对郑州大学第一附属医院收治的8例身高在120 cm左右的已行TBI的急性白血病患者进行回顾性研究,分别选择TD和HT治疗技术进行计划设计,其中TD分别设计2~12内奇数个均分射野的计划,且起始角度分别从180°和0°开始,其余计划参数都保持一致。最后对设计好的计划剂量分布进行统计,比较TD与HT治疗技术下的计划在靶区的平均剂量（PTV_Dmean）、均匀性指数（HI）和危及器官（OARs）受量,以评估计划质量,并比较治疗出束时间以评估治疗效率。结果 9野的TD计划相对于HT计划在PTV_Dmean和靶区HI能达到一致效果,差异无统计学意义。但TD<9野的计划相对于HT计划在PTV_Dmean（t=-3.12、-5.41、-20.33、-4.56、-7.22、-11.27,P<0.05）和靶区HI（t=-2.94、-5.18、-15.66、-4.31、-5.51、-9.13,P<0.05）无剂量学优势,差异有统计学意义。同时TD计划中起始角度对PTV_Dmean和靶区HI没有影响。在危及器官方面,≥ 7野TD计划与HT计划在左肺平均剂量与右肺平均剂量差异无统计学意义;左眼晶状体计划危及体积（PRV）的最大剂量（2.14±0.60）Gy与右眼晶状体PRV最大剂量（3.05±0.10）Gy在3野TD计划与HT计划差异有统计学意义（t=0.77、0.63,P<0.05）,眼晶状体PRV在最大剂量方面具有一定优势。治疗出束时间差异无统计学意义。TD计划中起始角度对左右眼晶状体PRV最大剂量、左肺平均剂量及治疗出束时间没有影响。结论 对于≥ 9野的TD调强计划相对于HT计划在靶区、危及器官及治疗出束时间方面能达到一致的结果,但在眼晶状体PRV最大剂量方面具有一定优势。     

不同全脑全脊髓放疗方式的剂量学比较及摆位误差对靶区的影响

目的 比较不同全脑全脊髓放射治疗（CSI）方式的剂量学差异及摆位误差对靶区剂量的影响。方法 选取2011年7月至2012年10月间接受CSI的9例患者的CT图像,分别完成常规二维（2D）、单野三维（3D-1）、三野三维（3D-3）、逆向调强（IMRT）及电子线的CSI计划,比较不同计划间靶区的覆盖度（V₉5）、高量（V₁₀₇）、最大剂量（D_max）、适形指数（CI）、剂量均一性指数（HI）;观察甲状腺、心脏、双肺、小肠、肾脏及全身正常组织5、15、25 Gy的受照体积。取患者每周的3个治疗中心（头部、上段脊髓、下段脊髓）的摆位误差值,将该周5次放疗计划的治疗中心分别按照此值移动得到新的放疗计划,比较不同计划方式新计划的靶区剂量与原计划的差异。结果 电子线V₉₅略低于其余各组（q=11.2~11.7,P<0.05）。IMRT具有最小的V₁₀₇（q=4.3~11.6,P<0.05）,其次为3D-3（q=4.3~7.1,P<0.05）;2D具有最大的D_max（q=2.4~2.7,P<0.05）;各组HI的差异无统计学意义;靶区CI从高至低依次为,IMRT>3D-3>2D、3D-1及电子线（q=7.1~14.3、7.1~9.6、0.00~0.01,P<0.05）。IMRT及电子线可以显著降低各器官及全身组织接受的15 Gy及25 Gy剂量;3D-3次之。但与2D及3D-1相比,3D-3及IMRT均不同程度增加了5 Gy的照射体积。引入摆位误差后,3D-1及3D-3靶区剂量与原计划差别小于其余各组（q=2.8~4.1,P<0.05）。结论 对于脊髓深度<4.5 cm者,电子线有可能是一种安全、可靠的治疗方式。3D-1虽适形度略差,但有减少摆位误差的影响、降低低剂量体积的趋势,仍为可考虑治疗方式之一。3D-3及IMRT显示了较好的靶区剂量分布,但其大范围低剂量体积需引起重视。     

全中枢神经系统肿瘤放疗技术的剂量学研究

目的 以三维适形放疗技术为参照,探讨中枢神经系统肿瘤简单调强(sIMRT)放疗技术的剂量学特性。方法 选取5名已行全脑全脊髓放疗患者,为每位患者设计3D-CRT计划、3野和5野sIMRT计划。利用剂量分布和剂量体积直方图(DVH),评价不同照射技术的靶区和正常器官的照射剂量、靶区剂量均匀性(HI),通过总的机器跳数(MU)间接比较不同照射技术的治疗时间。结果 3D-CRT在射野衔接处只有处方剂量的70%。计划靶区后缘的正常组织接受的剂量达到处方剂量的140%。3野和5野sIMRT计划的靶区剂量均匀性分别为0.09±0.01和0.08±0.01,优于3D-CRT计划的0.18±0.02 (t=7.80、7.65,P<0.05);心脏V₁₀分别为(8.4±1.9)%和(8.4±2.0)%,低于3D-CRT计划的(36.0±6.0)%(t=13.3、13,0,P<0.05);甲状腺V₂₀分别为(12.4±1.5)%和(12.4±1.6)%,低于3D-CRT计划的(69.4±5.7)%(t=26.3、26.4,P<0.05);喉V₂₀分别为(17.2±1.2)%和(17.9±1.5)%,低于3D-CRT计划的(89.4±7.0)%(t=25.5、26.5,P<0.05);靶区后缘正常组织V₃₀分别为(4.4±1.4)%,(4.9±1.9)%,低于3D-CRT计划的(31.9±6.1)%(t=8.5、10.1,P<0.05);平均机器跳数(MU)分别为1100±106和1160±129,高于3D-CRT计划的640±78。结论 3野和5野sIMRT计划在剂量分布、危及器官(OAR)保护、靶区剂量均匀性等方面均好于3D-CRT计划。     

容积旋转调强与固定野调强在晚期宫颈癌放疗的剂量学比较及疗效观察

目的 比较容积旋转调强（RapidArc）和固定野调强（IMRT）技术在宫颈癌根治性放疗的剂量学参数、急性不良反应发生率及疗效。方法 回顾性分析43例局部晚期（II_b~IV）宫颈癌患者,其中22例行容积旋转调强放疗,21例行固定野调强放疗,处方剂量50.4 Gy/28次,比较两组靶区剂量适形度、均匀性、靶区及危及器官的剂量、机器跳数及治疗时间;对比两组患者治疗期间的急性肠道及膀胱反应发生率;对比两组患者的完全缓解率和有效率。结果 与IMRT计划相比,RapidArc计划的靶区适形性指数CI略好,但差异无统计学意义（P > 0.05）;两组计划的靶区均匀性指数HI比较,差异无统计学意义（P > 0.05）。RapidArc计划中膀胱的V₄₀、V₅₀以及直肠的V₃₀、V₄₀、V₅₀均低于IMRT计划（t=-2.386、-2.397、-5.525、-2.883、-2.686,P < 0.05）,RapidArc计划中股骨头的平均剂量低于IMRT计划（t=-2.395,P < 0.05）。RapidArc较IMRT平均MU减少了53.15%,治疗所需平均时间缩短了62.14%。两组患者肠道、膀胱急性反应发生率相近。两组患者完全缓解率和有效率相近。结论 晚期宫颈癌根治性放疗中,采用RapidArc技术可以降低危及器官受量,缩短患者的治疗时间。     

基于4D-CT高通气功能肺组织避让的胸部肿瘤放疗计划可行性研究

目的 建立基于4D-CT肺通气功能图像的胸部肿瘤高通气功能肺避让(HVFLA)的放疗计划设计流程,确定HVFLA的放疗计划策略,为胸部肿瘤患者开展HVFLA放疗临床试验提供支持。方法 基于前期已经建立的4D-CT肺通气功能图像深度学习模型,搭建计算平台将其融入放疗计划流程,进一步回顾性入组10例行4D-CT模拟定位的胸部肿瘤患者,根据建立的模型获取每位患者的4D-CT肺通气功能图像,根据肺通气量相对值高低自动将肺通气功能区域三等分为高、中和低通气功能肺,并导入Pinnacle³治疗计划系统。对于每位患者,根据靶区处方剂量和危及器官的剂量限值要求,采用容积旋转调强技术,分别设计临床计划和HVFLA计划,要求每个计划均满足临床要求,其中,HVFLA计划增加限制高功能肺的优化条件。通过比较靶区、危及器官(双肺、心脏和脊髓)和高功能肺的剂量学参数评价计划,剂量学参数包括靶区的D₂、D₉₈和平均剂量,双肺和高功能肺的V₅、V₁₀、V₂₀、V₃₀和平均剂量,心脏的V₃₀、V₄₀和平均剂量,脊髓的D_{1 cm³}等。采用配对t检验的方法对两组计划统计分析。结果 临床计划和HVFLA计划的靶区和危及器官均满足临床要求,HVFLA计划高功能肺的平均剂量、V₅、V₁₀、V₂₀ 和V₃₀平均分别减少1.2 Gy、5.9%、4.2%、2.6%和2.3%,均具有统计学意义(t=-8.07、4.02、-6.02、-7.06、-6.77,P<0.05)。双肺、心脏和脊髓的剂量学参数差异均无统计学意义(P>0.05)。结论 建立了基于4D-CT肺通气功能图像的高功能肺避让的放疗计划设计流程,HVFLA计划可以显著降低高功能肺的受照剂量,双肺、心脏和脊髓受照剂量无显著变化。HVFLA放疗计划策略可行,可以为胸部肿瘤患者开展HVFLA放疗提供支持。     

多等中心计划设计方法在全中枢神经系统调强放疗中的应用

目的 探讨多中心计划设计方法(M-ISO)在全中枢神经系统放疗(CSI)中的应用价值。方法 选取在本院已接受螺旋断层放射治疗(HT)的10例CSI患者的治疗计划,将此10例患者带有靶区及危及器官的CT图像通过网络传输至Eclipse 11.0计划系统,重新用M-ISO进行计划优化,比较两种计划中靶区、危及器官的受照剂量、治疗时间和机器跳数的差异。结果 两种计划设计方案得到的靶区剂量均能满足临床要求。D_98%、D_2%和HI参数HT组优于M-ISO组(t=2.822、2.333、4.743,P<0.05),D_50%、D_mean和CI参数M-ISO组优于HT组(t=5.259、3.685、8.835,P<0.05);HT组计划对左右中耳、左右腮腺、颌下腺、甲状腺和肾脏的保护优于M-ISO组(t=4.365、5.416、2.674、3.077、2.782、2.607、4.659,P<0.05),而M-ISO组胰腺和小肠的受照剂量优于HT组(t=5.265、5.935,P<0.05);正常组织受照剂量M-ISO组V₁₀、V₂₀和V₃₆均低于HT组(t=3.57、3.701、2.602,P<0.05),而两组V₅差异无统计学意义;M-ISO组计划在治疗时间、机器跳数两项参数明显优于HT组(t=8.477、19.313,P<0.05),均值分别减少41.0%和94.1%。结论 多中心计划设计方法应用在全中枢调强放疗中能够满足剂量学临床要求,缩短治疗时间,减少机器损耗,可以作为一种新的计划设计方案推广。     

TomoDirect和TomoHelical技术在左侧乳腺癌保乳术后放疗中的剂量学比较

目的 比较4野和6野断层定野照射（TomoDirect）及断层螺旋照射（TomoHelical）技术在左侧乳腺癌保乳术后患者的放疗计划应用中的剂量学差异。方法 作为回顾性研究,本文选取16例已行调强（IMRT）治疗的左侧乳腺癌保乳术后患者,在螺旋断层放疗（Tomotherapy）计划系统上分别进行4野和6野的TomoDirect及TomoHelical 3种技术的模拟计划,比较3种技术设计的计划靶区和危及器官的剂量学差异及治疗参数。结果 3种技术设计的乳腺癌计划,均能满足临床要求。其中,4野TomoDirect技术对危及器官和正常组织,尤其是脊髓、健侧乳腺最大剂量D_max,肺的V₅,心脏D_mean（F=595.60、129.24、60.44、65.37,P<0.05）的保护优于TomoHelical技术,但在靶区剂量均匀性和适形度方面,以TomoHelical技术较优（F=2.78、60.93,P<0.05）。6野TomoDirect技术,在保证较TomoHelical技术低的危及器官限量的条件下,提高了4野TomoDirect技术的靶区均匀性和适形度。此外,TomoDirect技术的机器跳数均优于TomoHelical技术,有效地减少了患者治疗时间（F=24.89、3.75,P<0.05）。结论 对于左侧乳腺癌保乳术后放疗,6野TomoDirect技术设计的计划具有一定优势,与TomoHelical技术相比,6野TomoDirect大大降低了危及器官受量;与4野TomoDirect技术相比,6野TomoDirect靶区均匀性和适形度较优,更适宜于早期乳腺癌患者。     

Dosimetric comparison of helical tomotherapy,volumetric-modulated arc therapy,intensity-modulated radiotherapy,and field-in-field technique for synchronous bilateral breast cancer

Purpose: To compare the dosimetric characteristics of helical tomotherapy (HT), volumetric-modulated arc therapy (VMAT), intensity-modulated radiotherapy (IMRT), and tangential field-in-field technique (FIF) for the treatment of synchronous bilateral breast cancer (SBBC). Methods and Materials: Ten patients with early-stage unilateral breast cancer were selected for simulating the patients with SBBC in this retrospective analysis. Treatment plans with HT, VMAT, IMRT, and FIF were generated for each patient with a total dose of 50.4 Gy in 28 fractions to the target. Plan quality, namely conformity index (CI), homogeneity index (HI), dose-volume statistics of organs at risk (OARs), and beam-on time (BOT), were evaluated. Results: HT plans showed a lower mean heart dose (3.53 ± 0.31Gy) compared with the other plans (VMAT = 5.6 ± 1.36 Gy, IMRT = 3.80 ± 0.76 Gy, and FIF = 4.84 ± 2.13 Gy). Moreover, HT plans showed a significantly lower mean lung dose (p < 0.01) compared with the other plans: mean right lung doses were 6.81 ± 0.67, 10.32 ± 1.04, 9.07 ± 1.21, and 10.03 ± 1.22 Gy and mean left lung doses were 6.33 ± 0.87, 8.82 ± 0.91, 7.84 ± 1.07, and 8.64 ± 0.99 Gy for HT, VMAT, IMRT, and FIF plans, respectively. The mean dose to the left anterior descending artery was significantly lower in HT plans (p < 0.01) than in the other plans: HT = 19.41 ± 0.51 Gy, VMAT = 25.77 ± 7.23 Gy, IMRT = 27.87 ± 6.48 Gy, and FIF = 30.95 ± 10.17 Gy. FIF plans showed a worse CI and HI compared with the other plans. VMAT plans showed shorter BOT (average, 3.9 ± 0.2 minutes) than did HT (average, 11.0 ± 3.0 minutes), IMRT (average, 6.1 ± 0.5 minutes), and FIF (average, 4.6 ± 0.7 minutes) plans. Conclusions: In a dosimetric comparison for SBBC, HT provided the most favorable dose sparing of OARs. However, HT with longer BOT may increase patient discomfort and treatment uncertainty. VMAT enabled shorter BOT with acceptable doses to OARs and had a better CI than did FIF and IMRT.     

Dosimetric comparison of TomoDirect,helical tomotherapy,VMAT, and ff-IMRT for upper thoracic esophageal carcinoma

BackgroundThe new TomoDirect (TD) modality offers a nonrotational option with discrete beam angles. We aim to compare dosimetric parameters of TD, helical tomotherapy (HT), volumetric-modulated arc therapy (VMAT), and fixed-field intensity-modulated radiotherapy (ff-IMRT) for upper thoracic esophageal carcinoma (EC).MethodsTwenty patients with cT2-4N0-1M0 upper thoracic esophageal squamous cell carcinoma (ESCC) were enrolled. Four plans were generated using the same dose objectives for each patient: TD, HT, VMAT with a single arc, and ff-IMRT with 5 fields (5F). The prescribed doses were used to deliver 50.4 Gy/28F to the planning target volume (PTV50.4) and then provided a 9 Gy/5F boost to PTV59.4. Dose-volume histogram (DVH) statistics, dose uniformity, and dose homogeneity were analyzed to compare treatment plans.ResultsFor PTV59.4, the D₂, D₉₈, D_mean, and V_100% values in HT were significantly lower than other plans (all p < 0.05), and those in TD were significantly lower than VMAT and ff-IMRT (all p < 0.05). However, there was no significant difference in the D₂ and D_mean values between VMAT and ff-IMRT techniques (p > 0.05). The homogeneity index (HI) differed significantly for the 4 techniques of TD, HT, VMAT, and ff-IMRT (0.03 ± 0.01, 0.02 ± 0.01, 0.06 ± 0.02, and 0.05 ± 0.01, respectively; p < 0.001). The HI for TD was similar to HT (p = 0.166), and had statistically significant improvement compared to VMAT (p < 0.001) and ff-IMRT (p = 0.003). In comparison with the 4 conformity indices (CIs), there was no significant difference (p > 0.05). For PTV50.4, the D₂ and D_mean values in HT were significantly lower than other plans (all p < 0.05), and those in TD were significantly lower than VMAT and ff-IMRT (all p < 0.05). However, there was no significant difference in the D₂ and D_mean values between VMAT and ff-IMRT techniques (p > 0.05). No D₉₈ and V_100% parameters differed significantly among the 4 treatment types (p > 0.05). HT plans were provided for statistically significant improvement in HI (0.03 ± 0.01) compared to TD plans (0.05 ± 0.01, p = 0.003), VMAT (0.08 ± 0.03, p < 0.001), ff-IMRT (0.08 ± 0.01, p < 0.001). The HI revealed that TD was superior to VMAT and ff-IMRT (p < 0.05). The CI differed significantly for the 4 techniques of TD, HT, VMAT, and ff-IMRT (0.59 ± 0.10, 0.69 ± 0.11, 0.64 ± 0.09, and 0.64 ± 0.11, respectively; p = 0.035). The best CI was yielded by HT. We found no significant difference for the V₅, V₁₀, V₁₅, V₃₀, and the mean lung dose (MLD) among the 4 techniques (all p > 0.05). However, the V₂₀ differed significantly among TD, HT, VMAT, and ff-IMRT (21.50 ± 7.20%, 19.50 ± 5.55%, 17.65 ± 5.45%, and 16.35 ± 5.70%, respectively; p = 0.047). Average V₂₀ for the lungs was significantly improved by the TD plans compared to VMAT (p = 0.047), and ff-IMRT (p = 0.008). The V₅ value of the lung in TD was 49.30 ± 13.01%, lower than other plans, but there was no significant difference (p > 0.05). The D₁ of the spinal cord showed no significant difference among the 4 techniques (p = 0.056).ConclusionsAll techniques are able to provide a homogeneous and highly conformal dose distribution. The TD technique is a good option for treating upper thoracic EC involvement. It could achieve optimal low dose to the lungs and spinal cord with acceptable PTV coverage. HT is a good option as it could achieve quality dose conformality and uniformity, while TD generated superior conformality.     

Locoregional irradiation including internal mammary nodal region for left-sided breast cancer after breast conserving surgery: Dosimetric evaluation of 4 techniques

The present study aimed to compare 4 techniques in the planning of locoregional irradiation including internal mammary nodal region for left-sided breast cancer. Ten patients with left-sided breast cancer undergoing breast conservation surgery were enrolled. For each patient, 4 treatment plans were performed: a helical tomotherapy (HT) plan, a volumetric modulated arc therapy (VMAT) plan, a static intensity modulated radiation therapy (IMRT) plan, and a hybrid IMRT plan, designed to encompass the whole breast, internal mammary, and supraclavicular nodal regions. The prescribed dose of radiation was 50 Gy in 25 fractions. The dosimetric parameters of the target and organs at risk, as well as the dose delivery time, were evaluated and compared using an independent-samples t-test. The HT and VMAT plans had the best conformity and homogeneity. For the HT, VMAT, IMRT, and hybrid IMRT plans, the mean conformity index (CI) and homogeneity index (HI) were 0.83, 0.82, 0.8, and 0.77 (p < 0.001); and 1.07, 1.11, 1.14, and 1.14 (p < 0.001), respectively. The corresponding V₅₅ values were 0.3%, 11.4%, 27.02%, and 23.29% (p < 0.001). The D_mean and V₂₀ of the left lung obtained using the HT plan were significantly lower than those of VMAT, IMRT, and hybrid IMRT plans (p = 0.002, p = 0.004). There were no significant differences in D max of LAD descending coronary artery, or the D_mean of the heart among the 4 types of plans. The HT and VMAT plans had a lower dose to other organ at risk (OARs) compared with the IMRT and hybrid IMRT plans. The mean delivery times were 1042 ± 33 seconds, 136 ± 12 seconds, 450 ± 65 seconds, and 451 ± 70 seconds for the HT, VMAT, IMRT, and hybrid IMRT plans, respectively (p < 0.001). For whole breast plus supraclavicular and internal mammary nodal irradiation in left-sided breast cancer, the VMAT technique is recommended considering both the dose distribution and the delivery time. Under circumstances in which dose distribution is a priority, the HT technique is a valid option.     

有无均整器模式下鼻咽癌容积旋转调强放疗计划的剂量学比较

目的 比较加速器6 MV X射线非均整模式（FFF）和均整模式（FF）下局部进展期鼻咽癌容积调强（VMAT）计划的剂量学差异。方法 选取10例已行放疗的局部进展期鼻咽癌患者,分别设计FFF和FF VMAT计划,在满足临床要求的情况下,比较两种计划的剂量体积直方图（DVH）、靶区剂量分布、危及器官受量、靶区适形度、总机器跳数和治疗时间。 结果 两者均能满足临床治疗需求,FFF VMAT计划靶区最大剂量和平均剂量大于FF VMAT计划（t=-0.31、-0.35,P<0.05）,而计划靶区适形度略低（t=5.42,P<0.05）,左右晶状体的最大剂量低于FF VMAT计划（t=25.87、17.45,P<0.05）,其他危及器官剂量无明显差异。机器总跳数FFF VMAT为（699±16）MU,FF VMAT为（628±12）MU。平均单次治疗时间均约2 min,两者无明显差别。结论 两种计划均能满足临床治疗需求,FFF VMAT计划更利于保护照射野边缘危及器官,如晶状体。机器总跳数FFF VMAT计划高于FF VMAT计划但两者平均单次治疗时间无明显差别。     

Comparative evaluation of treatment plan quality for a prototype biology-guided radiotherapy system in the treatment of nasopharyngeal carcinoma

We aimed to compare prototype treatment plans for a new biology-guided radiotherapy (BgRT) machine in its intensity-modulated radiation therapy (IMRT) mode with those using existing IMRT delivery techniques in treatment of nasopharyngeal carcinoma (NPC). We retrospectively selected ten previous NPC patients treated in 33 fractions according to the NRG-HN001 treatment protocol. Three treatment plans were generated for each patient: a helical tomotherapy (HT) plan with a 2.5-cm jaw, a volumetric modulated arc therapy (VMAT) plan using 2 to 4 6-MV arc fields, and a prototype IMRT plan for a new BgRT system which uses a 6-MV photon beam on a ring gantry that rotates at 60 rotations per minute with a couch that moves in small incremental steps. Treatment plans were compared using dosimetric parameters to planning target volumes (PTVs) and organs at risk (OARs) as specified by the NRG-HN001 protocol. Plans for the three modalities had comparable dose coverage, mean dose, and dose heterogeneity to the primary PTV, while the prototype IMRT plans had greater dose heterogeneity to the non-primary PTVs, with the average homogeneity index ranging from 1.28 to 1.50 in the prototype plans. Six of all the 7 OAR mean dose parameters were lower with statistical significance in the prototype plans compared to the HT and VMAT plans with the other mean dose parameter being comparable, and all the 18 OAR maximum dose parameters were comparable or lower with statistical significance in the prototype plans. The average left and right parotid mean doses in the prototype plans were 10.5 Gy and 10.4 Gy lower than those in the HT plans, respectively, and were 5.1 Gy and 5.2 Gy lower than those in the VMAT plans, respectively. Compared to that with the HT and VMAT plans, the treatment time was longer with statistical significance with the prototype IMRT plans. Based on dosimetric comparison of ten NPC cases, the prototype IMRT plans achieved comparable or better critical organ sparing compared to the HT and VMAT plans for definitive NPC radiotherapy. However, there was higher dose heterogeneity to non-primary targets and longer estimated treatment time with the prototype plans.