乳腺癌术后胸壁电子线放射治疗单野与分野计划比较

目的：乳腺癌术后胸壁电子线放射治疗时单野与分野治疗对整个胸壁照射区剂量分布比较。方法：对乳腺癌根治术后病人进行模拟CT定位,用Varian的Eclipse治疗计划系统进行CT图像重建、靶区勾画。6MeV或9MeV电子线对所勾画的靶区进行单野和分野计划设计,计算并比较整个靶区的剂量分布。结果：乳腺癌术后胸壁照射由单野改成二野照射后,80％剂量曲线所包靶区体积由47％上升到84％,90％剂量曲线所包靶区体积由28％上升到72％。结论：进行乳腺癌根治术后大胸壁电子线照射时,单野照射剂量分布不均且靠近内乳区和腋中线区剂量严重不足,若在病人体表弯曲处进行分野,分野后进行二野照射则大大提高内乳区和腋中线区的剂量,提高了整个靶区的剂量,从而满足临床剂量要求。     

乳腺癌改良根治术后胸壁电子线照射研究

目的：探讨乳腺癌改良根治术后胸壁电子线照射（electron beam chest wall irradiation,EBCWI）的剂量学特点,为临床应用提供参考。方法：以10例左乳癌改良根治术后的定位CT图像为基础,借助Eclipse 8.6三维治疗计划系统软件（Varian Clinac iX加速器配备）进行EBCWI剂量学研究。由资深放疗医师确定CTV和心脏及肺组织边界,模拟制定不同能量电子线以不同机架角方向实施胸壁照射的放疗计划。评价各治疗计划的剂量分布和靶区及心肺组织的体积剂量关系（DVH）,并尝试用Bolus优化计划结果。结果：从照射角度来看,20°-40°机架角治疗计划的剂量分布较好并且靶区平均剂量（CTVmean）较高。从射线能量分析,以95%CTV50Gy为处方剂量,6MeV电子线无法达到剂量要求;9MeV、12MeV和15MeV电子线在满足靶剂量时,同侧肺≥20Gy的体积百分比（LungV20）分别为31%±6%、50%±4%和65%±8%;心脏≥30Gy的体积百分比（HeartV30）分别为10%±2%、23%±3%和38%±5%;精心设计Bolus可以显著降低心肺组织剂量而对靶区剂量几无影响。结论：乳癌根治术后EBCWI宜选择9-12MeV电子线从偏患侧30°左右的机架角实施照射,并应恰当应用Bolus以进一步优化剂量分布。     

乳腺癌改良根治术后胸壁电子线照射研究

目的:探讨乳腺癌改良根治术后胸壁电子线照射(electron beam chest wall irradiation,EBCWI)的剂量学特点,为临床应用提供参考。方法:以10例左乳癌改良根治术后的定位CT图像为基础,借助Eclipse 8.6三维治疗计划系统软件(Varian Clinac iX加速器配备)进行EBCWI剂量学研究。由资深放疗医师确定CTV和心脏及肺组织边界,模拟制定不同能量电子线以不同机架角方向实施胸壁照射的放疗计划。评价各治疗计划的剂量分布和靶区及心肺组织的体积剂量关系(DVH),并尝试用Bolus优化计划结果。结果:从照射角度来看,20°-40°机架角治疗计划的剂量分布较好并且靶区平均剂量(CTVmean)较高。从射线能量分析,以95%CTV50Gy为处方剂量,6MeV电子线无法达到剂量要求;9MeV、12MeV和15MeV电子线在满足靶剂量时,同侧肺≥20Gy的体积百分比(LungV20)分别为31%±6%、50%±4%和65%±8%;心脏≥30Gy的体积百分比(HeartV30)分别为10%±2%、23%±3%和38%±5%;精心设计Bolus可以显著降低心肺组织剂量而对靶区剂量几无影响。结论:乳癌根治术后EBCWI宜选择9-12MeV电子线从偏患侧30°左右的机架角实施照射,并应恰当应用Bolus以进一步优化剂量分布。     

乳腺癌改良根治术后胸壁切线野计划和电子线计划的剂量学比较

目的:比较乳腺癌改良根治术后胸壁X线切线野放疗计划和电子线单野放疗计划肿瘤靶区与正常组织的剂量学分布差异,探讨最合适的照射方式.方法:选取2007年8月～2008年6月收治的30例有胸壁照射适应证的乳腺癌改良根治术后患者.进行CT模拟定位,利用三维治疗计划系统为每例患者设计两种不同的胸壁放射治疗计划:X线切线野计划和电子线单野计划,胸壁处方剂量均为50Gy/25次,用剂量体积直方图(DVH)来比较两种计划中临床靶区(CTV)和心脏、同侧肺的剂量学差异.结果:左侧胸壁切线野计划和电子线野计划肿瘤靶区的最大剂量(Dmax)分别为5306±17cGy、5536±301cGy(P=0.02);右侧胸壁Dmax分别为5228±136cGy,5554±253cGy(P=0.01),统计学有显著性差异.两种计划肿瘤靶区其余指标(Dmean、D90和V105%、V110%以及不均匀指数HI)均无统计学差异.左侧胸壁切线野计划和电子线野计划同侧肺平均剂量分别为1095±243cGy和1723±624(P=-0.001),肺V20分别为21±5%和36±13%(P=0.001),两者均有显著性差异.其余指标(心脏的平均剂量、V30)无统计学差异.右侧胸壁两种计划所有正常组织指标均无统计学差异.结论:乳腺癌改良根治术后胸壁x线切线野放疗比电子线单野放疗有一定的剂量优势,可以减少胸壁的最高剂量,左侧胸壁能减少同侧肺受照射的体积和剂量,更好地保护正常组织.     

乳腺癌术后胸壁照射技术剂量分布的研究

目的：对乳腺癌术后胸壁放射治疗几种常用照射技术的剂量分布特点进行研究。方法：对乳腺癌手术后患者和做了标记的测量体模，按放疗体位做CT扫描，CT影像经网络送入三维TPS，在TPS上设计4种照射方案，并在人体模上进行模拟照射（参考剂量1Gy)，用热释光剂量仪进行实际测量。结果：实验结果表明除电子弧形旋转照射外，其它3种照射技术的胸壁剂量都较均匀（胸壁平均剂量＞0．90Gy)。电子线弧形旋转照射 和X线双切线影＋内乳区电子线野技术由于在内乳区设野保证了内乳区有充足的剂量（内乳点剂量＞0．90Gy)，但是后者在2个野交界处易形成剂量冷热点。单纯X线切线野和适形野技术在内乳区可产生欠剂量情况，体积剂量直方图显示电子线旋转照射技术肺部受高剂量照体积最小，适形野技术也使肺部受高剂量照射体积明显减小。在体表加盖1．0－1．5cm的组织等效填充物后，4种照射技术的皮肤剂量可提高到0．90Gy以上。结论：乳腺癌胸壁照射技术有不同的剂量分布特点，在临床应用时应视患者具体情况选择使用。     

乳腺癌改良根治术后CT模拟胸壁电子线照射的剂量学探讨

目的评价乳腺癌改良根治术后CT模拟定位下胸壁电子线照射的靶区和心肺受照体积和剂量分布情况。方法20例有胸壁照射适应证的乳腺癌改良根治术后患者,行CT模拟定位,三维治疗计划系统将CT图像进行数字化重建,勾画胸壁CTV及心、肺等危及器官,并计算胸壁及其心、肺受照体积和受照剂量。胸壁处方剂量为5000cGy。结果左侧乳腺癌靶区的Dmax为(5536±301)cGy、Dmean为(4823±129)cGy、D90为(4543±290)cGy,同侧肺Dmean为(1724±624)cGy、V20为(36±13)%。心脏Dmean为(1008±457)cGy、V30为(13±9)%。右侧乳腺癌靶区的Dmax为(5554±253)cGy、Dmean为(4783±89)cGy、D90为(4496±101)cGy、同侧肺Dmean为(1416±567)cGy、V20为(30±12)%。结论通过CT模拟定位制定胸壁电子线照射放疗计划,能更准确地了解靶区和正常组织的剂量分布,从而能更好地优化放疗计划。     

乳腺癌改良根治术后常规放疗剂量学分析

目的 分析乳腺癌改良根治术后常规二维放疗模式下胸壁及锁骨上区剂量分布和内乳区非计划性受量。方法 回顾分析2015-2016年间20例改良根治术后放疗的女性乳腺癌患者资料,左右乳腺癌各10例。放疗范围为患侧胸壁和锁骨上下区,处方剂量43.5Gy (2.9 Gy/次)。胸壁采用单前野电子线照射,锁骨上下野予以6MV X线单前野照射。同时比较锁骨上下采用前后对穿野照射时的剂量分布。结果 锁骨上单前野照射中85%患者接受了D90≥90%处方剂量,前后对穿野中所有患者均达到了D90≥90%处方剂量(39.15Gy, EQD2≥45Gy),胸壁单前电子线野D90中位数为35.38Gy。非计划性内乳区域照射的平均剂量中位数为13.65Gy。体重指数小患者锁骨上、胸壁的D90更高(P=0.039、0.347)。结论 锁骨上下单前X线野能满足绝大多数受量≥90%的处方剂量照射,而前后对穿野在满足所有人受量需求时不增加正常组织受量。单前电子线野胸壁剂量分布不佳,内乳区有一定的非计划性照射,但剂量有限。体重指数是影响剂量分布的因素。     

乳房保留术后野中野正向调强全乳房照射的腋窝淋巴结剂量学研究

目的 研究早期乳腺癌患者保乳术后采用野中野正向调强技术进行单纯乳房照射时各站腋窝淋巴结剂量分布及影响因素。方法 37例乳腺癌患者保乳术后采用“野中野”技术照射乳房,在定位CT图像上勾画患侧第Ⅰ、Ⅱ、Ⅲ站和胸肌间淋巴结靶区,并勾画腋静脉,在三维放疗计划软件上逐站分析其所接受的剂量。配对t检验分析影响腋窝淋巴结剂量分布的因素。结果 在全乳PTV处方剂量50 Gy分25次情况下,第Ⅰ、Ⅱ、Ⅲ站和胸肌间淋巴结被95%处方剂量所包括体积比平均值分别为34.7%、6.1%、0.4%和39.6%,D_mean分别为30.8、15.7、5.0 Gy和28.8 Gy;腋静脉以下和以上淋巴结区域被95%处方剂量包括的体积比为45.6%和0.7%,D_mean为38.2 Gy和6.7 Gy。乳房照射野的上界距离肱骨头的距离是影响腋静脉以下淋巴结区域D_mean的唯一有意义因素(P=0.037)。结论 全乳正向调强野中野技术对腋静脉以下腋窝淋巴结的实际照射剂量是不可忽略的,必须在分析保乳术后腋窝淋巴结控制率时予以考虑。     

乳腺癌保乳术后全乳野中野适形调强放射治疗技术

目的:探讨乳腺癌保乳术后全乳野中野适形调强照射技术方法,并与常规全乳切线野照射技术进行剂量学对比.方法:选取22例早期乳腺癌保乳术后患者在CT模拟机下对乳腺部位行薄层定位扫描,将定位图像传输至治疗计划系统进行全乳野中野计划设计:在全乳两切线适形野的基础上挡去高剂量区部分,另设计2-4个小跳数射野以降低靶区最高剂量和调整高剂量区的范围及所在位置.处方剂量50Gy/25次,要求95%的靶区接受处方剂量;然后利用其CT模拟定位资料按照常规切线野射野方法在治疗计划上模拟常规切线野治疗计划,对野中野计划和常规射野计划进行靶区适形性、靶区均匀性和危及器官受量的比较.结果:野中野适形调强放射治疗技术的适形度、均匀性优于常规切线野照射,靶区内超过110%处方剂量的体积明显小于常规切线野技术.减少了肺组织V20的体积,降低了心脏的平均剂量和受照体积.结论:乳腺癌保乳术后全乳野中野适形调强放射治疗技术是一种有益的全乳照射技术.     

乳腺癌改良根治术后CT模拟胸壁切线野照射剂量学分析

目的评价胸壁切线野照射CT模拟定位的价值.方法28例有胸壁照射适应症的乳腺癌改良根治术后患者,进行CT模拟定位,三维治疗计划系统将CT图象进行数字化重建,勾画胸壁CTV及心、肺等危及器官,胸壁处方剂量为5 000cGy,计算胸壁及其心、肺受照体积和受照剂量.结果右肺体积为1 403±234cm3,左肺为1 133±186cm3,切线野中心肺厚度(CLD)平均为2.4±0.5cm.百分受照体积(PIV)右肺为(13.12±3.26)%,左肺为(12.72±3.58)%,心脏为(2.47±1.87)%,建立一元回归方程,肺PIV=-1.308+6.226CLD(r=0.727,P＜0.001).胸壁体积为441±142cm3,Dmean为4 831±352cGy,胸壁V95%、V105%和V110%分别为(95.4±5.3)%、(18.7±15.4)%和(53±7.5)%.不加组织补偿胸壁Dmean和Dmin低于胸壁加组织补偿照射(P＜0.05).加30°和45°楔形板照射后胸壁受照剂量均匀性优于无楔形板和加15°楔形板照射,统计学差异接近显著性意义.结论乳腺癌改良根治术后胸壁切线野照射采用CT模拟定位可准确获得靶区和危及器官的剂量和体积信息,有助于评估心、肺并发症的发生.     

Dose volume histogram analysis of lung radiation from chest wall treatment: comparison of electron arc and tangential photon beam techniques

The technique of electron arc irradiation of the post-mastectomy chest wall was developed to improve dose uniformity and to reduce lung irradiation in comparison to that seen with standard chest wall tangent photon beam methods. Because of the cephalocaudal variation in chest wall shape and thickness, electron arc treatment planning requires anatomical detail provided by multiple axial CT images of the thorax. To compare the fixed beam and rotational techniques, computer simulated beams covering the chest wall and internal mammary lymphatics were retrospectively applied to the CT-derived contours obtained during treatment planning for 12 consecutive patients receiving adjuvant chest wall treatment by electron arc. The lung dose distribution for each technique was calculated using heterogeneity corrections. The multiplanar 2-dimensional isodose distributions were summed to provide estimated 3-dimensional dose distributions of integral histograms. These reveal that for most of these patients a modest to large improvement in volume-dose relationship occurs with the electron arc technique.     

A custom three-dimensional electron bolus technique for optimization of postmastectomy irradiation.

PURPOSE: Postmastectomy irradiation (PMI) is a technically complex treatment requiring consideration of the primary tumor location, possible risk of internal mammary node involvement, varying chest wall thicknesses secondary to surgical defects or body habitus, and risk of damaging normal underlying structures. In this report, we describe the application of a customized three-dimensional (3D) electron bolus technique for delivering PMI. METHODS AND MATERIALS: A customized electron bolus was designed using a 3D planning system. Computed tomography (CT) images of each patient were obtained in treatment position and the volume to be treated was identified. The distal surface of the wax bolus matched the skin surface, and the proximal surface was designed to conform to the 90% isodose surface to the distal surface of the planning target volume (PTV). Dose was calculated with a pencil-beam algorithm correcting for patient heterogeneity. The bolus was then fabricated from modeling wax using a computer-controlled milling device. To aid in quality assurance, CT images with the bolus in place were generated and the dose distribution was computed using these images. RESULTS: This technique optimized the dose distribution while minimizing irradiation of normal tissues. The use of a single anterior field eliminated field junction sites. Two patients who benefited from this option are described: one with altered chest wall geometry (congenital pectus excavatum), and one with recurrent disease in the medial chest wall and internal mammary chain (IMC) area. CONCLUSION: The use of custom 3D electron bolus for PMI is an effective method for optimizing dose delivery. The radiation dose distribution is highly conformal, dose heterogeneity is reduced compared to standard techniques in certain suboptimal settings, and excellent immediate outcome is obtained.     

Obliquely incident electron beams for irradiation of the internal mammary lymph nodes

For irradiation of the internal mammary lymph nodes, together with irradiation of the breast, a number of more or less standardised techniques are used. Regarding some disadvantages of these techniques, a modified method is discussed, that uses an obliquely incident electron beam for the mammary lymph node irradiation. Dose distributions of obliquely incident electron beams are measured and compared with the results of a treatment planning program. A procedure to match this obliquely incident beam to the adjacent tangential photon beams, that irradiate the breast, is described and the resulting dose distribution is compared with a standard technique. Applications with this technique and its usefulness are discussed.     

CT模拟定位减少鼻咽癌放射治疗中的视神经剂量

目的：比较CT模拟定位治疗计划和常规普通模拟定位治疗计划治疗鼻咽癌时视神经的放射剂量。方法：对33例T1－T4期的鼻咽癌用Picker PQ5000螺旋CT及AcQPlan 4.1.1软件系统进行模拟定位。首先利用治疗计划系统上的数字重建的射线影像（DRR），根据患者的CT（或MRI）和临床检查结果，按照常规使用普通X射线模拟机拍摄定位片的定位方法设计出照射野。然后在所有CT层面逐层勾画出鼻咽肿瘤的大体肿瘤体积（GTV）、临床靶体积（CTV）和计划靶体积（PTV）。同时逐个勾画出周围重要顺官轮廓，特别小心勾画出眼球后视神经至视交叉的行程。根据肿瘤和周围重要器官之间在三维空间的相互关系设计合理的照射野。分别对两种治疗计划进行剂量计算，将靶中心剂量归一为100％，主要比较2种计划的肿瘤靶区、眼球和视神经最大放射剂量、平均剂量和中位剂量。同时比较2种计划放射野内视神经的长度。结果：不论是CT模拟计划还是常规模拟计划，鼻咽GTV和CTV均可有满意的剂量分布。但眼球、视神经和视交叉所接受的最大剂量、平均剂量和中位剂量都有显著差别。CT模拟计划中上述器官的受量明显低于常规计划。CT模拟计划可将更多的视神经保护在照射野外，避免不必要的照射。结论：CT模拟定位治疗计划减少了鼻咽癌放射治疗中视神经的放射剂量。     

Computer-CT planning of the electron boost in definitive breast irradiation

Treatment planning of the electron boost in breast irradiation at this institution is performed by using information from CT scanning and from surgical clips used to define the tumor bed. A refinement of this technique, taking into account the surgical axis of approach, using computer-CT planning is now implemented. The location of the scar and the clips are digitized using a computer to define the tumor bed dimensions. With 3-D computer software a line, simulating the surgical axis and the central ray of the electron beam, is drawn between the deepest clip and the surgical scar. This beam's eye view along the surgical axis is projected onto a screen as a starting point. Appropriate gantry angle, treatment table position, beam energy, and precise shaping of the electron field borders with a 2 cm margin around the clips and the scar are determined. Simulation films comparing clinically set-up fields and computer-CT planned fields were reviewed. In only 5 of 17 patients did the clinically set-up field have adequate inclusion of the tumor bed within the treatment volume. Computer-CT planned fields ensured adequate inclusion of the tumor bed in all, including the remaining 12. In 7 patients obvious increased sparing of normal breast tissue was seen with computer-CT planned fields. This technique enables accurate placement of a shaped electron field and further refinement of electron boost treatment planning. This is especially true in situations in which the tumor bed is located at a site distant from the lumpectomy scar rather than directly beneath it and in cases where the tumor bed lies deep within the breast.     

Comparison of classic simulation and virtual simulation in breast irradiation: prospective study on 14 patients]

PURPOSE: To compare conventional 2D simulation and virtual simulation on 14 patients with breast cancer. PATIENTS AND METHODS: Patients were simulated for treatment using standard procedure. They subsequently underwent CT scan in the treatment position. The CTV was defined as breast tissue. The PTV was obtained by adding a 3D margin of 1 cm around CTV. Organs at risk (lungs and heart) were outlined. Ballistics and dose distribution obtained with the two planning methods were compared. RESULTS: With conventional simulation, 95% of CTV received 95% of the dose prescribed. Virtual simulation significantly improved dosimetric coverage of PTV without increasing irradiation volume of lung and heart. In 2D simulation, using three slices allowed optimisation by adjusting wedge angle. The five-slice plan was a much better predictor of the maximum dose regions when compared to the three-slice plan. Using entire CT data didn't give any benefit. CONCLUSION: Variations in CTV delineation and PTV definition limit interest of virtual simulation. In classic simulation, a 5 CT slice-plan can be used to optimise dose distribution.     

Three-dimensional photon treatment planning in carcinoma of the larynx

The role of three-dimensional (3-D) treatment planning in the definitive treatment of carcinoma of the larynx with radiation was evaluated at four institutions as part of an NCI contract. A total of 30 different treatment approaches were devised for two patients with larynx cancer. CT scans were obtained for both patients and various treatment planning tools were employed to optimize beam arrangements and to evaluate the resulting dose distribution. The effect on dose distribution of a number of factors was also examined: 1) the use of dose calculation algorithms which correct for tissue inhomogeneities, 2) the variation of the CT numbers used for inhomogeneity corrections to simulate inaccuracies in the knowledge of the CT numbers, and 3) the modification of beam energy. A multitude of data was used in plan evaluation and a numerical score was given to each plan to estimate the tumor control probability and the normal tissue complication probability. We found 3-D treatment planning to be of potential value in optimizing treatment plans in larynx cancer. Improved target coverage was achieved when complete information describing 3-D geometry of the anatomy was utilized. In some cases, the treatment planning tools employed, such as the beam's eye view, helped devise novel beam arrangements which were useful alternatives to standard techniques. We found little effect of change in CT number on dose distributions. A comparison between dose distributions calculated with tissue inhomogeneity corrections to those calculated without this correction showed little difference. We did find some improvement in the dose to the primary tumor volume at lower beam energies, but with an increased larynx volume potentially receiving doses above tolerance.     

鼻咽癌常规放疗中电子线L形野照射技术应用研究

 目的　探索一种能更好地解决鼻咽癌常规放疗中射野之间衔接问题的新方法。方法　使用三维计划系统模拟鼻咽癌2D-适形放疗（CRT）或3D-CRT治疗中电子线L形野照射技术与常规放疗颈后电子线野照射技术的布野方法,进行剂量学分布比较。结果　电子线L形野照射技术与颈后电子线野照射技术的靶区剂量超过6000 cGy的包绕体积都达到95 %以上,满足临床上肿瘤治疗的剂量需要,但颈后电子线野照射技术出现明显的剂量热点,最高剂量可达8900 cGy,电子线L形野照射技术的最高剂量达7200 cGy。电子线L形野照射技术的喉部高剂量范围比颈后电子线野照射技术小,前者喉部剂量超过6500 cGy的体积为19.64 %,后者为31.95 %。结论　电子线L形野照射技术在照射野之间衔接和剂量分布方面都具有较好的优势,值得临床推广应用。