乳腺癌保乳术后部分乳腺三种放疗计划的剂量学比较

目的 比较容积弧形调强（VMAT）、固定野动态调强（IMRT）及三维适形放疗（3D-CRT）技术对乳腺癌保乳术后采用部分乳腺放疗的剂量学差异。方法 选取20例临床分期为T_1-2N₀M₀的早期乳腺癌保乳术后患者进行VMAT,并同时设计IMRT及3D-CRT,比较3种计划的剂量学参数,包括剂量-体积直方图（DVH）、靶区剂量适形度、靶区及危及器官的剂量、机器跳数及治疗时间。结果 IMRT及VMAT计划靶区剂量分布优于3D-CRT计划,其中最大剂量,平均剂量及适形指数（CI）组间比较差异具有统计学意义（F=14.86、8.57、18.23,P<0.05）。正常组织受量：VMAT计划在患侧乳腺V₅上优于IMRT及3D-CRT计划（F=5.83,P<0.05）;IMRT在患侧肺V₂₀、V₅及D₅上有优势（F=16.39、3.62、4.81,P<0.05）;在对侧肺的统计中,IMRT计划在最大剂量及D₅上可以得到比VMAT和3D-CRT更低的剂量（F=3.99、3.43,P<0.05）;VMAT、3D-CRT和IMRT计划所需机器跳数值分别为621.0±111.9、707.3±130.9、1161.4±315.6,计划间的差异有统计学意义（F=31.30,P<0.05）。VMAT、3D-CRT和IMRT计划所需治疗时间分别为（1.5±0.2）、（7.0±1.6）、（11.5±1.9）min。结论 IMRT和VMAT计划靶区剂量分布优于3D-CRT计划,而不提高患侧肺剂量。对于部分乳腺癌的放疗,容积弧形调强放疗在降低机器跳数和减少治疗时间方面具有明显优势。     

胸中段食管癌适形调强放疗和三维适形放疗方案的应用探讨

目的比较胸中段食管癌适形调强放疗(IMRT)和三维适形放疗(3D-CRT)两种不同技术中计划靶区(PTV)及正常组织的受量。方法对52例ⅡB-Ⅳ期胸中段食管癌患者用同一放疗计划系统分别设计IMRT和3D-CRT根治性放疗计划,应用剂量体积直方图(DVH)比较两种方法中计划靶区和正常组织受量并且计算计划靶区适形指数(CI)和剂量不均匀指数(HI)。结果 IMRT方法的PTV适形度优于3D-CRT;脊髓剂量的最大值低于3D-CRT,但无统计学差异;心脏接受V25和V40的体积百分比低于3D-CRT;IMRT显著降低了肺部V10和V20的有效体积,但其肺部的V5大于3D-CRT。结论在可接受的放射性损伤的基础上,IMRT技术较3D-CRT能够提高行根治性放疗的ⅡB-Ⅳ期胸中段食管癌患者靶区剂量,靶区适形度高,但可使肺组织受到更大容积的低剂量照射。     

保乳术后固定野动态调强与容积调强放疗的剂量学比较

目的 比较早期乳腺癌保乳术后固定野动态调强与容积调强放疗治疗靶区和危及器官的剂量学差异.方法 20例左侧乳腺癌患者(均女性,24～75岁)保乳术后接受放疗,在同一患者CT影像上分别进行2野共面动态调强和容积调强(RapidArc)两种治疗计划设计.在剂量-体积直方图中读取两种计划的靶区剂量分布参数,心脏、双侧肺及对侧乳腺受照剂量和体积,对各参数的均数进行比较;并比较两者平均机器跳数和平均治疗时间的差异.结果 RapidArc较IMRT计划CTV V95%增加了0.65%(t=5.16,P=0.001),V105%下降了10.96%(t=-2.05,P=0.055),V110%下降了1.48%(t=-1.33,P=0.197).RapidArc计划的适形指数(CI)和均匀性指数(HI)均优于IMRT治疗计划,分别为0.88±0.02 vs 0.74±0.03(t=18.54,P＜0.001),1.11±0.01 Vs 1.12±0.02(t=-2.44,P=0.025).两种计划中左肺V20和Dmax比较差异无统计学意义,但在RapidArc计划中V10、V5、Dmix、Dmean明显增高,V5增高了接近30%.心脏V30和Dmax在两计划中无明显差异,而RapidArc计划的V10增加了18%,V5增加50%.RapidArc计划的右乳V5和右肺V5较IMRT分别增加了9.33%(t=9.31,P＜0.001)和3.04%(t=5.64,P＜0.001).RapidArc和IMRT平均机器跳数分别是608和437 MU(t=10.86,P＜0.001),平均治疗时间111.3和103.6 s(t=3.57,P=0.002).结论 早期乳腺癌保乳术后全乳腺RapidAre放疗与2野动态调强放疗相比,能明显改善靶区剂量分布均匀性.对于危及器官,高剂量区两种治疗计划之间无明显差异,低剂量区RapidArc的照射范围明显增加.与2野动态调强相比,RapidArc放疗机器跳数增加,治疗时间延长.

Abstract：

Objective To compare the dosimetric difference between volumetric are modulation with RapidArc and fixed field dynamic IMRT for breast cancer radiotherapy after breast-conserving surgery.Methods Twenty patients with early left-sided breast cancer received radiotherapy after breast-conserving surgery.After target definition,treatment planning was performed by RapidAre and two fixed fields dynamic IMRT respectively on the same CT scan.The target dose distribution,homogeneity of the breast,and the irradiation dose and volume for the lungs,heart,and eontralateral breast were read in the dosevolume histogram (DVH) and compared between RapidAre and IMRT.The treatment delivery time and monitor units were also compared.Results In comparison with the IMRT planning,the homogeneity of clinical target volume (CTV) ,the volume proportion of 95% prescribed dose (V95%) was significantly higher by 0.65% in RapidAre (t =5.16,P = 0.001) ,and the V105% and V110% were lower by 10.96% and 1.48 % respectively,however,without statistical significance (t =-2.05 ,P =0.055 and t =-1.33 ,P =0.197).The conformal index of planning target volume (PTV) by the Rap~dAre planning was (0.88±0.02),significantly higher than that by the IMRT planning [(0.74±0.03),t = 18.54,P < 0.001].The homogeneity index (HI) of PTV by the RapidArc planning was 1.11±0.01,significantly lower than that by the IMRT planning (1.12±0.02,t =-2.44,P =0.02).There were no significant differences in the maximum dose (Dmax) and V20 for the ipsilateral lung between the RapidArc and IMRT planning,but the values of V10,V5 ,Dmin and Dmean by RapidArc planning were all significantly higher than those by the IMRT planning (all P < 0.01).The values of max dose and V30 for the heart were similar by both techniques,but the values of V10 and V5 by the RapidArc planning were significantly higher (by 18% and 50% ,respectively).The V5 of the contralateral breast and lung by the RapidArc planning were increased by 9.33% and 3.04% respectively compared to the IMRT planning.The mean MU of the RapidArc was 608 MU,significantly higher than that by the IMRT planning (437 MU,t = 10.86,P < 0.001).The treatment time by the RapidArc planning was 111.3 s,significantly longer than that by IMRT planning (103.6 s,t = 3.57,P = 0.002).Conclusions The RapidArc planning improves the dose distribution of CTV and homogeneity of PTV for breast cancer radiotherapy after breast-conserving surgery.However,it significantly enlarges the volume of normal tissues irradiated in low dose areas,prolongs the treatment delivery time,and increases the MU value in comparison with IMRT.     

三维适形、逆向调强和旋转调强放疗技术治疗胸段食管癌的剂量学比较

目的 比较胸段食管癌3种放疗技术( 3D-CRT、IMRT、RapidArc)的剂量学特点,并分析3种技术的优劣及应用特点.方法 15例胸段食管癌患者入组,依据CT图像,勾画靶区,针对患者的同一套CT图像的相同靶区分别制定3D-CRT、5野IMRT(IMRT5)、7野IMRT( IMRT7)、9野IMRT(IMRT9)、单弧Arc( Arc1)、双弧Arc( Arc2)共6套计划.PTV处方剂量为40 Gy分20次4周+19.6 Gy分14次7d.结果 3D-CRT计划各项靶区剂量学参数明显差于IMRT计划及RapidArc计划(t=5.77、3.52,P＜0.05),6套计划的PTV V95(％)分别为:3D-CRT (91.55 ±2.90),IMRT5(96.66±1.05),IMRT7 (96.87±1.23),IMRT (96.81±1.16),Arcl (94.98±1.41),Arc2 (95.93±1.32).RapidArc计划的靶区适形度(CI)最好(t=3.76,10.01,P＜0.05),IMRT计划的靶区均匀性(HI)最好(t =3.93、3.37,P＜0.05).危及器官参数RapidArc与IMRT各计划之间差异无统计学意义.3D-CRT和RapidArc计划的机器跳数明显少于IMRT计划,差异高达75％.结论 对于胸段食管癌患者,采用IMRT或RapidArc技术可以在保护正常组织的同时,涵盖临床必需的治疗靶区.3D-CRT计划对降低正常组织低剂量散射区方面优势明显.RapidArc计划靶区剂量学参数与IMRT计划比较未见明显优势.     

容积旋转调强放疗和常规调强放疗技术在乳腺癌保乳术后同步推量中的剂量学比较

 目的 比较容积旋转调强放疗(VMAT)和常规调强放疗(IMRT)两种技术在乳腺癌保乳术后同步推量放疗中剂量学差异。方法 随机选择10例左侧乳腺癌保乳术后患者,使用MONACO 5.1计划系统,分别设计VMAT和IMRT计划,处方剂量均为PTV_50Gy/25 f、PGTVtb60 Gy/25 f,评估两种计划靶区剂量适形指数(CI)、均匀性指数(HI),以及正常器官受照剂量(Gy)、机器跳数(MU)及治疗时间。结果 VMAT计划中靶区剂量的适形度明显优于IMRT(P<0.05),而患侧肺V₅、V₁₀、V₂₀及健侧肺V₅稍高于IMRT组(P<0.05)。结论 对于乳腺癌保乳术后同步推量放疗,VMAT和IMRT计划都可以满足临床剂量学的要求,VMAT在适形度方面对于IMRT计划有优势,并缩短了治疗时间。     

左侧乳腺癌患者根治术后常规调强计划与电子束适形联合调强计划的剂量比较

目的比较左侧乳腺癌患者根治术后常规调强放射治疗计划(intensity modulated radiotherapy, IMRT)与电子束适形放疗(electron beam conformal radiotherapy, EBCRT)联合调强放疗计划的剂量学差异。方法选择2018年6月至2021年10月于宁波市第一医院放化疗中心收治的20例左侧乳腺癌根治术后患者资料, 计划靶区(plan target volume, PTV)包括锁骨上下淋巴结引流区域计划靶区(PTVsc)和患侧胸壁计划靶区(PTVcw), 处方剂量均为50 Gy/25次。所有患者均采用美国Varian Eclipse治疗计划系统(treatment planning system, TPS)设计两种放疗计划, 然后对比两种放疗计划的剂量学参数差异。结果所有20例患者的IMRT计划全部满足临床要求, 与此同时EBCRT联合IMRT计划中有2例患者因患侧肺剂量参数超出本单位的剂量限定标准而不被临床接受, 两例失败计划的胸壁最大深度分别为3.7和4.4 cm, 使用的电子束能量分别为12和15 MeV。其余18例患者的胸...     

乳腺癌术后胸壁大体积复发二野和六野调强放疗剂量学比较

目的 比较乳腺癌术后胸壁大体积复发2野和6野调强放疗的计划差异.方法 对8例乳腺切除术后胸壁大体积复发病例,Pinnacle计划系统上分别对PTV进行2野调强和6野调强放疗计划设计,PTV处方剂量为50 Gy/25次(GTV后续计划补量至66～70 Gy),比较2种计划95％处方剂量PTV适形指数(CI)、均匀性指数(HI)及心脏、同侧肺剂量.结果 6野IMRT计划的CI和HI均优于2野IMRT计划,6野和2野的CI分别为(0.66±0.08)和(0.53±0.10)(t=7.99,P＜0.05),HI分别为(1.36±0.08)和(2.19±0.78)(t=9.04,P＜0.05).2个计划中肺V5、V10、V20、V35和心脏Dmax、V35、Dmean值比较差异无统计学意义.结论 乳腺癌切除术后胸壁大体积复发患者行放疗,6野静态逆向调强放疗计划靶区覆盖优于2野,而心肺受量方面无明显差异.     

旋转调强与固定野逆向调强放疗在颅脑多发转移瘤中的剂量学比较研究

目的 比较旋转调强(RapidArc)与固定野调强(IMRT)放疗在颅脑多发转移瘤中的剂量学差异。方法 针对10例多发脑转移瘤患者分别设计3种放疗计划:固定野逆向调强(IMRT),RapidArc单弧旋转调强(RA1),双弧旋转调强(RA2)。在保证计划均满足临床要求前提下,分别比较3种计划的靶区剂量分布、危及器官及靶区外正常组织的受照剂量、机器跳数以及治疗时间,探讨其剂量学差异。结果 3种计划均满足临床要求,在靶区适形度和均匀性方面,RA2计划优于IMRT(Z＝-2.803、-2.094,P<0.05)和RA1(Z＝-2.448、-2.191,P＜0.05),RA1计划与IMRT计划差别不大。RA1、RA2计划中的双侧晶体、双侧眼球、脑干的最大剂量均显著低于IMRT(Z＝-2.803～-2.191,P <0.05)。RA2计划评估的双侧视神经最大剂量均显著低于IMRT(Z＝-2.293、-2.701,P<0.05)。RA1、RA2计划中的机器跳数相对于IMRT平均分别减少了43%和24%,缩短了治疗时间。结论 单弧和双弧旋转调强计划均可达到或优于IMRT计划的靶区剂量分布,能更好地降低部分危及器官的受照剂量,同时可以显著降低机器跳数和治疗实施时间。     

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。     

Dosimetric comparison of 3D conformal,IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)

The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies including gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10 Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V₁₀) or 20 Gy (V₂₀) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V₅ and D₅). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung. In terms of MU and delivery time, V-MAT is significantly more efficient for APBI than for conventional 3D-CRT and static-beam IMRT.     

Single-arc volumetric-modulated arc therapy (sVMAT) as adjuvant treatment for gastric cancer: Dosimetric comparisons with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT)

To compare the dosimetric differences between the single-arc volumetric-modulated arc therapy (sVMAT), 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for gastric cancer as adjuvant radiotherapy. Twelve patients were retrospectively analyzed. In each patient's case, the parameters were compared based on the dose-volume histogram (DVH) of the sVMAT, 3D-CRT, and IMRT plans, respectively. Three techniques showed similar target dose coverage. The maximum and mean doses of the target were significantly higher in the sVMAT plans than that in 3D-CRT plans and in the 3D-CRT/IMRT plans, respectively, but these differences were clinically acceptable. The IMRT and sVMAT plans successfully achieved better target dose conformity, reduced the V_20/30, and mean dose of the left kidney, as well as the V_20/30 of the liver, compared with the 3D-CRT plans. And the sVMAT technique reduced the V₂₀ of the liver much significantly. Although the maximum dose of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5 and 40.6 Gy), these data were still under the constraints. Not much difference was found in the analysis of the parameters of the right kidney, intestine, and heart. The IMRT and sVMAT plans achieved similar dose distribution to the target, but superior to the 3D-CRT plans, in adjuvant radiotherapy for gastric cancer. The sVMAT technique improved the dose sparings of the left kidney and liver, compared with the 3D-CRT technique, but showed few dosimetric advantages over the IMRT technique. Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with gastric cancer after surgery in the future.     

An in silico comparative dosimetric study of postmastectomy locoregional irradiation using intensity-modulated vs 3-dimensional conventional radiotherapy

An in silico dosimetric evaluation of intensity-modulated radiation therapy (IMRT) vs 3-dimensional conventional radiation therapy (3D-CRT) treatment plans in postmastectomy radiation therapy (PMRT) to the chest wall and regional lymphatics was conducted. Twenty-five consecutive patients with breast cancer referred for locoregional PMRT, stages T_2-4 with N_1-3, were planned to receive 50?Gy in 25 fractions with IMRT. Additionally, a 3D-CRT plan was generated using identical contours for the clinical target volumes (CTV), planning target volumes (PTV), and organs at risk (OAR). Treatment plans were assessed using dose-volume histogram (DVH) parameters of D₉₈, D₉₅, D₅₀, D₂, and homogeneity index for individual CTVs and PTVs. OARs evaluated were ipsilateral and contralateral lungs, heart, spinal cord, and opposite breast. Most DVH parameters pertaining to CTVs and PTVs significantly favored IMRT. V₂₀ for ipsilateral and contralateral lungs, D₃₃ of heart and maximum dose to spinal cord favored IMRT (all p?<?0.001). The mean dose to the opposite breast was significantly lesser with 3D-CRT (5.8?±?1.8?Gy vs 2.0?±?1.0?Gy, p?<?0.001). Thus, except for the mean dose to the opposite breast, the compliance to DVH constraints applied to PTV and OARs were significantly better with IMRT. At a median follow-up of 76 months (7-91), none had locoregional failure or pulmonary or cardiac morbidity. For PMRT, requiring comprehensive irradiation to both chest wall and regional lymphatics, IMRT offers superior dosimetric advantages over 3D-CRT. This was also corroborated by long-term outcomes in these patients treated with IMRT.     

乳腺癌术后放疗3种治疗计划的剂量学研究

目的 评估螺旋断层调强放疗(helical tomotherapy,HT)、常规直线加速器逆向调强放疗(IMRT)和三维适形放疗(3D- CRT)3种治疗计划对乳腺癌术后胸壁照射的剂量影响和正常组织受照剂量体积对比。方法 选择10例早期乳腺癌改良根治术后患者CT定位图像,由同一医生勾画PTV,统一处方剂量50 Gy/ 25次。每例图像分别做HT、IMRT和3D- CRT 3种治疗计划,并对心脏、健侧肺和患侧肺受照射剂量体积、靶区适形度指数、剂量均匀指数和处方剂量所覆盖的靶体积等物理参数进行比较。结果 95%和100%的处方剂量覆盖的PTV体积在HT、IMRT和3D- CRT组分别为99.13%和95.87%、97.80%和94.05%、96.37%和87.29%。HT、IMRT 和3D-CRT组的适形指数和靶区均匀指数分别为0.80±0.10和1.09±0.03、0.65±0.07和1.14±0.02、0.40±0.08和1.17±0.04。心脏V₅~V₂₀以3D- CRT组最少,其次是HT组。患侧肺V₅接受的照射剂量体积以3D- CRT组最小,与HT和IMRT两组相比差异均有统计学意义。健侧肺V₅和V₁₀以3D- CRT组最少。结论 乳腺癌术后胸壁照射的靶区适形度和剂量均匀指数HT组最好;心脏、健侧肺和患侧肺低剂量区最小的依次是3D-CRT、HT和IMRT组。     

三维适形与简化调强放疗技术在非小细胞肺癌放疗中的剂量学比较

目的 用剂量学方法比较三维适形(3D-CRT)和简化调强放疗(sIMRT)技术用于治疗非小细胞肺癌(NSCLC)的差异。方法 选择接受放疗的10例NSCLC患者进行研究。对每例患者进行3D-CRT和sIMRT的治疗计划设计,处方剂量为60 Gy(2 Gy/次),所有计划都使95%靶区体积达到处方剂量要求。并用ADAC Pinnacl计划系统提供的卷积或迭加算法对两种放疗技术的治疗计划进行剂量计算,比较靶区剂量分布均匀性和适形性,以及危及正常组织剂量体积直方图参数。结果 3D-CRT与sIMRT放疗计划的等剂量线和DVH相近,sIMRT计划的靶区剂量均匀性和适形性略优于3D-CRT计划,sIMRT放疗计划中肺的平均剂量、V₅、V₁₀、V₂₀分别比3D-CRT降低14.81%、17.88%、19.15%、27.78%,而食管、心脏、脊髓等危及器官的受量基本相同。结论 对于NSCLC,sIMRT放疗技术在某些方面具有3D-CRT无法替代的优势,值得在临床推广应用。     

快速旋转调强与五野动态调强在乳腺癌 保乳术后放疗中的剂量学比较

目的 比较乳腺癌保乳术后RapidArc计划与五野动态调强(5F-IMRT)计划的剂量学差异。方法 选择8例左侧乳腺癌保乳术后女性患者,处方剂量为50 Gy/ 25次。分别设计RapidArc计划与5F-IMRT计划。比较两种计划的靶区适形度指数、均匀性指数、靶区覆盖度和危及器官的受照剂量体积,同时比较两组计划实施时的治疗时间和机器跳数。结果 在两种计划的靶区比较中,RapidArc计划的靶区适形度指数为(0.88±0.03),高于5F-IMRT计划的(0.79±0.02)(t=8.28,P<0.05);RapidArc计划的均匀性指数为(9.01±0.73),优于5F-IMRT计划的(10.44±1.08)(t=-2.73,P<0.05)。两组计划在同侧肺受照剂量体积比较中RapidArc计划的D_mean、V₁₀、V₂₀、V₃₀小于5F-IMRT计划(t=-7.53、-7.20、-8.39、-7.80,P<0.05),但RapidArc计划中的V₅较5F-IMRT计划增加了约16% (t=5.67,P<0.05);心脏的受照剂量体积比较中RapidArc计划中的D_mean、V₅、V₁₀均高于5F-IMRT(t=10.46、28.76、5.40,P<0.05),但在RapidArc计划中心脏的V₃₀低于5F-IMRT (t=-6.12,P<0.05)。对侧肺和对侧乳腺的V₅在RapidArc计划中明显高于5F-IMRT计划 (肺:t=21.50,P<0.05;乳腺:t=5.44,P<0.05)。RapidArc计划中机器跳数减少了25%,平均治疗时间节省了60%。结论 乳腺癌保乳术后RapidArc计划与5F-IMRT计划比较提高了靶区的适形度和均匀度,减少了高剂量区的受照体积,降低了机器跳数,缩短了治疗时间,但增加了正常组织低剂量区的受照体积。     

Volumetric modulated arc radiotherapy for esophageal cancer

A treatment planning study was performed to evaluate the performance of volumetric arc modulation with RapidArc (RA) against 3D conformal radiation therapy (3D-CRT) and conventional intensity-modulated radiation therapy (IMRT) techniques for esophageal cancer. Computed tomgraphy scans of 10 patients were included in the study. 3D-CRT, 4-field IMRT, and single-arc and double-arc RA plans were generated with the aim to spare organs at risk (OAR) and healthy tissue while enforcing highly conformal target coverage. The planning objective was to deliver 54 Gy to the planning target volume (PTV) in 30 fractions. Plans were evaluated based on target conformity and dose-volume histograms of organs at risk (lung, spinal cord, and heart). The monitor unit (MU) and treatment delivery time were also evaluated to measure the treatment efficiency. The IMRT plan improves target conformity and spares OAR when compared with 3D-CRT. Target conformity improved with RA plans compared with IMRT. The mean lung dose was similar in all techniques. However, RA plans showed a reduction in the volume of the lung irradiated at V_20Gy and V_30Gy dose levels (range, 4.62–17.98%) compared with IMRT plans. The mean dose and D_35% of heart for the RA plans were better than the IMRT by 0.5–5.8%. Mean V_10Gy and integral dose to healthy tissue were almost similar in all techniques. But RA plans resulted in a reduced low-level dose bath (15–20 Gy) in the range of 14–16% compared with IMRT plans. The average MU needed to deliver the prescribed dose by RA technique was reduced by 20–25% compared with IMRT technique. The preliminary study on RA for esophageal cancers showed improvements in sparing OAR and healthy tissue with reduced beam-on time, whereas only double-arc RA offered improved target coverage compared with IMRT and 3D-CRT plans.