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。     

螺旋断层放疗在同时性双侧乳腺癌中的应用研究

目的 研究螺旋断层放疗(helical tomotherapy,HT)与容积旋转调强放疗(volumetric modulated arc therapy,VMAT)在同时性双侧乳腺癌术后放疗中的剂量学、治疗出束时间差异,探讨HT技术的临床应用可行性。方法 回顾性分析并选取2017年2月至2022年5月于广西医科大学第四附属医院行改良根治术后放疗的9例同时性双侧乳腺癌患者为研究对象,对每例患者分别使用Precision计划系统制定HT计划和RayStation计划系统制定VMAT计划。所得所有计划按照计划类型分为HT组和VMAT组。采用配对样本t检验比较两种放疗技术的靶区和危及器官(organ at risk,OAR)的剂量学参数及治疗出束时间。结果 两组计划均能满足临床治疗要求。HT组的靶区覆盖度(D_95%和V_100%)、适形指数CI、平均剂量D_mean和中位剂量D_50%均优于VMAT组,差异均有统计学意义(t=-3.21、-3.39、-5.03、3.76、4.97,P < 0.05);两组计划的靶区最大剂量D_2%、最小剂量D_98%、高剂量体积V_107%和V_110%、均匀性指数HI的差异无统计学意义(P > 0.05)。OAR方面,HT组的双肺V₂₀、D_mean均明显低于VMAT组,但双肺V₅明显高于VMAT组,差异均有统计学意义(t=-3.01、3.83、-2.81,P < 0.05);同时HT组明显降低了心脏的V₂₀、V₃₀、V₄₀、D_mean以及肝脏的V₂₀、D_mean,差异均有统计学意义(t=3.76、-2.83、-2.74、5.93、4.57、4.48,P < 0.05);其他OAR脊髓、甲状腺、肱骨头的受照剂量差异无统计学意义(P > 0.05)。HT组的治疗出束时间显著高于VMAT组(t=11.32,P < 0.05)。结论 与VMAT相比,HT具备更大的剂量学优势,能提供更优的靶区覆盖度、适形度和平均剂量,且可明显降低OAR双肺、心脏和肝脏的整体受照剂量,但双肺的低剂量区V₅、治疗时间多于VMAT,不过仍满足临床治疗需求,故可考虑将HT技术应用于同时性双侧乳腺癌的改良根治术后放疗。     

两种全中枢神经系统放疗技术患者有效剂量的比较

目的比较螺旋断层放疗（helical tomotherapy,HT）和多等中心放疗（multi-ISO radiotherapy,M-ISO）两种技术在全中枢神经系统放疗（craniospinal irradiation,CSI）过程中患者的有效剂量。方法选取在本院已接受全中枢神经系统放射治疗的9例儿童患者,分别运用螺旋断层放疗和多等中心放疗两种技术对此9例患者重新进行治疗计划设计。对9例患者共18个治疗计划的患者有效剂量进行计算,运用配对t检验比较两种放疗技术过程中患者有效剂量的差异。结果HT和M-ISO计划均满足临床要求,两组计划靶区剂量D_95%差异无统计学意义（P>0.05）;HT组的D_98%、D_2%、均匀性指数（HI）优于M-ISO计划（t=2.762、2.413、4.563,P<0.05）;M-ISO组的D_50%、D_mean和适形指数（CI）优于HT计划（t=5.259、3.685、7.815,P<0.05）。两种计划方法对危及器官的保护各有优势;9例患者全身有效剂量HT计划高于M-ISO计划,差异有统计学意义（t=5.921,P<0.01）。结论 HT与M-ISO两种技术在全中枢神经系统放疗中各有优势,HT组计划低剂量区域范围对于患者有效剂量影响较大,全中枢放疗计划设计时应关注低剂量辐射范围。     

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。     

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。     

早期鼻咽癌螺旋断层放疗颈部皮肤受量的剂量学研究

目的 探索早期鼻咽癌螺旋断层放射治疗（Tomotherapy）计划设计过程中降低颈部皮肤受照剂量的方法。方法 采用简单随机抽样法选取17例已接受螺旋断层放射治疗的早期鼻咽癌病例，将各病例颈部外轮廓内缩3 mm生成新的组织器官即颈部皮肤组织，同时清除各靶区与颈部皮肤组织的交叉部分；针对上述处理过的病例进行两组计划设计，常规（TP）组按照常规计划方法进行螺旋断层放疗计划设计；新计划（NP）组是将颈部皮肤组织作为危及器官进行剂量限制计划设计；比较两组计划中各靶区以及危及器官的剂量参数、机器跳数以及治疗时间等参数。结果 两组计划均能满足临床处方要求，两组计划各靶区的D₉₈、D₉₅以及D₂差异均无统计学意义（P>0.05）；NP组的脑干D_max、脊髓D_{1 cm³}、右侧腮腺D_mean高于TP组接受的剂量（t=2.47、2.34、2.77，P<0.05），左颞颌关节D_max较TP组低（t=2.30，P<0.05），皮肤V₃₀、V₄₀、V₅₀、V₆₀比TP组明显降低（t=8.37、6.02、5.82、4.89，P<0.05）。NP组单次总机器跳数比TP组平均减少6.3%，单次实际执行时间比TP组平均减少8.1%。结论 早期鼻咽癌螺旋断层放射治疗应该勾画颈部皮肤，并在计划设计过程中将其作为危及器官进行剂量限制，该方法能够有效降低颈部皮肤受照剂量，减轻放射治疗过程中皮肤反应，提高患者生活质量。     

基于离线自适应放疗的宫颈癌病例靶区外扩边界及其剂量评估

目的 分析行容积旋转调强放射治疗宫颈癌病例在离线自适应放疗（off-line ART）中靶区的外扩边界及其剂量学参数。方法 选取50例宫颈癌病例,采用随机配对法均分成试验组与对照组,每例患者每周行2次锥形束CT （CBCT）扫描,记录整个治疗过程中,患者在左右（LR）、前后（AP）与头脚（CC）方向上的摆位误差值,利用靶区外放边界公式计算新的临床靶区体积（CTV）-计划靶区体积（PTV）的外扩边界。同时,将摆位误差值归一至等中心点（ISO）,回归治疗计划系统,对照组在原有PTV的基础上移动ISO后重新计算剂量,试验组在得到新的外扩边界后移动ISO重新计算剂量,比较评估两组计划在重新计算剂量后的CTV与危及器官剂量学参数。结果 根据靶区外放边界公式,CTV外扩边界在LR、AP和CC方向上分别为0.45、0.46和0.82 cm。治疗计划系统（TPS）剂量再计算结果显示,试验组在CTV的D_100%与D_95%上优于对照组（t=-8.16、-6.73,P<0.05）,在股骨头的V₄₀、V₃₀以及D_mean上均优于对照组（t=3.14、-9.52、-7.48,P<0.05）,在骨盆的V₃₄与D_mean上均优于对照组（t=10.14、-9.38,P<0.05）。结论 在宫颈癌的容积旋转调强放射治疗中,off-line ART技术可以有效地减少CTV-PTV的外扩边界,并且可以提高靶区的照射覆盖范围,减少相应危及器官的照射剂量。     

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。     

TomoDirect技术在全脑全脊髓放疗中的应用

目的 为全脑全脊髓放疗建立新的TomoDirect技术(TD)布野方案,并评价剂量学参数。方法 对本院收治的7例全脑全脊髓放疗患者进行回顾性研究,在Tomo计划系统分别设计5野TD、3野TD和螺旋断层治疗(helical tomotherapy, HT)计划,比较3种计划的靶区适形指数(CI)、均匀性指数(HI)、危及器官受量、治疗时间和机器跳数(MU)。结果 除3野TD计划外其余两者均能获得较好的靶区适形度和均匀性。其中5野TD计划靶区受量明显优于3野TD计划,但略逊于HT计划;危及器官受量则各有优势。5野TD、3野TD和HT计划的靶区平均CI分别为0.79、0.57和0.88;靶区HI分别为1.06、1.16和1.05;双肺V₂₀分别为1.99%、3.30%和2.16%;心脏平均剂量分别为6.17、12.38和10.72 Gy;肝脏平均剂量分别为5.21、5.14和4.62 Gy;左侧肾脏平均剂量分别为4.30、1.99和5.03 Gy;右侧肾脏平均剂量分别为4.42、2.09和4.91 Gy。靶区以外的正常组织V₅分别为46.80%、28.06%和55.54%。5野TD计划的治疗时间最短,5野TD、3野TD及HT计划的平均治疗时间分别为677、721和907 s,MU数分别是8 773、9 657和12 581。结论 5野的TD技术应用于全脑全脊髓放疗具有一定优势,适用于难以坚持长时间治疗,且希望减少低剂量范围的患者。     

鼻咽癌三种调强放疗计划剂量学对比研究

目的 对比鼻咽癌常规固定野调强（IMRT）、容积旋转调强（VMAT）以及断层调强（HT）3种不同调强放疗计划的剂量学差异。方法 选择18例接受VMAT治疗的鼻咽癌患者,以相同处方剂量和目标条件分别重新进行IMRT和HT计划设计。比较3种计划靶区的均匀度（HI）、适形度（CI）、最大剂量以及平均剂量。危及器官的最大量和平均量以及感兴趣区的剂量体积、计划执行时间和机器跳数（MU）。结果 3种计划在靶区的覆盖率满足临床要求。IMRT计划在靶区的HI和CI方面结果最差,HT计划结果最优。危及器官方面,IMRT计划受量最高,HT计划的脊髓、脑干和腮腺受量最低;但对于视神经、晶状体以及视交叉HT计划的受量最高而VMAT计划的受量最低。IMRT的治疗时间（8.0±0.5） min高于VMAT（3.9±0.1）min和HT（7.4±0.9）min。与VMAT相比,IMRT每次治疗为（711.4±78.7）MU,高于VMAT的（596.4±33.7）MU。结论 鼻咽癌IMRT、VMAT以及HT计划在靶区覆盖和危及器官保护上都可以达到临床要求,在靶区的适形度和均匀性上HT计划优于VMAT和IMRT,但在治疗时间和加速器的机器跳数上VMAT较有优势。     

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.     

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.     

一种Eclipse调强放疗计划优化方法在上段食管癌的应用评估

目的 评估一种利用Eclipse治疗计划系统的基部剂量计划进行补偿(base dose plan compensation, BDPC)的调强放疗(IMRT)计划优化方法应用于上段食管癌的可行性。方法 选择19例上段食管癌患者,设计初始IMRT计划,并分别用BDPC法和热点冷点控制(hot and cold spot control, HCSC)法进一步优化。比较两种计划的靶区覆盖、适形指数(CI)、均匀指数(HI)、危及器官保护、计划设计时间、机器跳数(MU)以及投照时间。结果 BDPC计划高危靶区PTV64的D_2%低于HCSC计划(Z=-3.823, P<0.05),CI和HI明显优于HCSC计划(Z=-3.662、-3.745,P<0.05),而D_98%差异无统计学意义(P>0.05)。BDPC计划低危靶区PTV54的CI高于HCSC计划(Z=-3.340,P<0.05),D_95%和D_98%低于HCSC计划(Z=-3.582、-2.616,P<0.05)。BDPC计划脊髓和肺的剂量均略低于HCSC计划(Z=-3.625~-3.369,P<0.05)。BDPC与HCSC计划设计时间分别为(26.05±0.88)和(33.73±3.24) min (Z =-3.823,P<0.05),MU分别为1 019±167和1 003±159(Z=-2.616,P<0.05),投照时间分别为(3.52±0.29)和(3.50±0.28)min(Z=-2.548,P<0.05)。结论 BDPC优化方法在上段食管癌应用能明显提高靶区剂量的均匀性和适形性,减少危及器官剂量,并且操作简便,能提高计划设计效率。     

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.