全脑全脊髓照射技术的改进

目的:介绍全脑全脊髓放射治疗的一种新技术。方法:患者采用仰卧位,在整体定位板上做颈肩和体膜固定,行CT扫描定位,将图像传输治疗计划系统,进行三维重建。按照全脑全脊髓照射的要求勾画靶区,设计治疗计划,调整剂量分布。治疗前行CBCT扫描,进行在线的体位验证。结果:通过计划系统进行剂量计算,可以直观显示靶区的剂量分布并加以调整,计划照射野衔接处没有明显的剂量冷点和热点出现体位验证结果符合临床要求;通过CBCT在线验证,保证位置准确。结论:全脑全脊髓放射治疗采用了仰卧位热塑膜固定,较传统的俯卧位使患者更舒适,治疗过程中体位容易保持,确保治疗的准确;CT模拟定位方法,较传统的模拟机定位简单易行,且定位精确;用计划系统计算剂量分布并进行调整,使靶区剂量分布均匀,避免照射野衔接处剂量分布出现冷、热点。     

全脑全脊髓照射仰卧位CT模拟定位技术

目的：探讨全脑全脊髓照射仰卧位CT模拟定位技术。方法：7名患者分别躺在真空负压袋固定器上，进行CT模拟定位，打印正侧位数字重建射线彩像（DRR）图，放射治疗前拍摄正侧位定位验证片，测量解剖参考点和射野边界之间的距离。结果：患者左右方向及背腹方向误差在2mm以内。人体上下方向误差在4mm以内；放疗后，患者受照射的皮肤部位均出现色素沉着。结论：仰卧位全脑全脊髓照射CT模拟定位技术可用于俯卧位不合作的患者。     

食管癌扩大照射野放射治疗的剂量学研究

目的:应用三维适形放射治疗计划对10例胸段食管癌的扩大野和常规四野以及常规三野照射进行对比分析,并探讨食管癌扩大野照射技术的剂量分布特点.材料和方法:进行根治性同步放化疗的胸段食管癌患者10例,CT扫描后由医生勾画靶区,淋巴结引流区和危及器官,给每例患者设计3种放疗计划即扩大野照射、常规四野照射和常规三野照射,再对各个计划DVH的各项参数进行综合评价分析.结果:三种照射方式的剂量分布均能满足肿瘤靶区剂量要求,靶区内剂量分布相对均匀,各组间无显著差异,而靶区内剂量以扩大野照射最高;扩大野的淋巴引流区的受照剂量较其它两计划高;对于危及器官,扩大野的双肺V20高于其它两计划,扩大野60%心脏的受照剂量高于常规四野和常规三野,常规四野高于常规三野,脊髓的受照剂量最大值和平均值以常规三野最小.结论:食管癌扩大野照射靶区内照射剂量高于其他两种照射,扩大野靶区包括了淋巴引流区,降低了区域局部复发的概率,临床结果提示有利于提高生存率.     

一种全颅全脊髓适形照射野的布野方案

目的:探讨一种简便易行、剂量准确性高的全颅全脊髓的适形照射的布野方案。方法:100多例髓母细胞瘤患者,俯卧位躺在特制的头颅固定器和真空负压袋上,进行CT模拟定位,在头颅放置3个标记点作为全颅野照射中心,进床30 cm左右作为全脊髓野的照射中心,通过多次改变全颅野的下界和脊髓野的上界来保证照射野内的剂量准确性。结果:经过上述方法设计的治疗方案,使得全颅全脊髓的放射治疗剂量分布精确,操作方便并且定位时间不长,临床疗效好。治疗时不在一个点上接野,确保脊髓的剂量无冷热点。结论:适形移动的全颅全脊髓的治疗技术操作方便,定位时间短,剂量分布准确,临床疗效好,副作用小,值得推广。     

三维适型放疗与调强放疗在胸中段食管癌根治性放疗中的 剂量学比较

目的 比较胸中段食管癌三维适型放疗与调强放疗对靶区和危及器官的剂量学影响,探讨两种放射治疗方法在胸中段食管癌根治性放疗中重要器官受保护的优劣,寻找食管癌放射治疗的理想计划模式。方法 15例经病理证实胸中段食管鳞癌患者,经体位固定、CT模拟定位扫描成像传输到治疗计划系统、勾画肿瘤体积、临床靶区体积和危及器官。15例病例均做三维适型和调强计划,60 Gy/30次,评估/优化后应用剂量体积直方图比较两种计划对靶区及危及器官的剂量学影响。结果 在相同靶区、相同剂量模式下,对胸中段食管癌患者的放射治疗中,调强放疗对靶区剂量的分布及对危及器官的保护均优于三维适形放疗。结论 胸中段食管鳞癌,长度4~18 cm放射治疗,三维适型/调强放疗对危及器官剂量学的影响有明显差异。同部位的肿瘤受到相同剂量照射情况下,调强放疗对危及器官的影响较三维适型放疗小,靶区剂量分布均匀度好。     

MDCT小肠造影受检者体位的优选

目的 评价多层螺旋CT小肠造影最佳体位选择.方法 60例受检者口服对比剂充盈胃和小肠,随机分为2组:35例采取俯卧位,25例采取仰卧位.患者在60分钟内分4次口服总量2000ml 2.5％等渗甘露醇溶液,行256-多层螺旋CT小肠造影(MDCTE),平扫结束后行增强扫描,通过横断面及多平面重建,测量肠腔宽度、肠壁厚度,对各组测量及评价结果进行统计学分析.结果 在肠腔宽度、肠壁厚度方面,者二组无明显差异;49例小肠充盈程度为满意-较满意的受检者,俯卧位明显优于仰卧位;肠管分布、显示病变等方面,俯卧位也优于仰卧位.结论 小肠MDCT造影行俯卧位检查更有助于小肠疾病的临床诊断.     

CBCT引导下不同体位子宫肿瘤IMRT摆位误差及其外放边界

目的:研究在千伏级CBCT引导下,不同体位子宫肿瘤患者调强放射治疗中的摆位误差及靶区的外放边界。方法:采用医科达直线加速器机载影像系统对251例子宫肿瘤患者接受调强放射治疗前行CBCT扫描,其中仰卧位117例、俯卧位134例。系统自动重建图像并与治疗计划CT图像进行配准,获得俯卧位与仰卧位患者x、y、z方向摆位误差,并分别计算患者临床靶区到计划靶区(PTV)的外放边界。结果:所有患者共行3 128次扫描,俯卧位1 679次与仰卧位1 449次。x、y、z轴的误差均小于0.3 cm为981次,占31.36%;距离治疗等中心偏差距离小于0.3 cm为415次,占13.27%。考虑摆位误差方向时,俯卧位患者的x、y、z方向上摆位误差分别为(0.109 5±0.380 7)、(-0.035 1±0.569 2)、(0.075 1±0.285 2)cm;仰卧位患者的x、y、z方向上摆位误差分别为(0.001 1±0.303 4)、(0.118 4±0.583 0)、(0.033 2±0.248 0)cm。而考虑摆位误差大小时,俯卧位患者的x、y、z方向上摆位误差分别(0.300 8±0.257 7)、(0.442 8±0.359 2)、(0.227 1±0.188 2)cm;仰卧位患者的x、y、z方向上摆位误差分别为(0.229 3±0.198 6)、(0.470 2±0.364 4)、(0.183 2±0.170 3)cm。俯卧位患者PTV在x、y、z方向分别外放0.540、0.486、0.387 cm;仰卧位患者PTV在x、y、z方向分别外放0.215、0.704、0.257 cm。结论:子宫肿瘤患者仰卧位和俯卧位这两种体位的摆位误差有一定差异,以距离治疗等中心偏差距离小于0.3 cm作为摆位误差校准较适合;俯卧位患者的靶区在x、y、z方向分别外放0.540、0.486、0.387 cm;而仰卧位患者则外放0.215、0.704、0.257 cm。     

射波刀颅骨追踪俯卧位与仰卧位治疗精度对比

目的:探讨射波刀颅骨追踪俯卧位与仰卧位治疗精度的差异,为射波刀颅骨追踪俯卧位治疗提供理论依据。方法:分别对安装有EBT3免冲洗胶片的头颈模体采用俯卧位与仰卧位进行CT扫描、计划设计和模拟射波刀治疗。采用E2E软件分析曝光后的EBT3免洗胶片,对比射波刀颅骨追踪俯卧位与仰卧位治疗精度。结果:头颈模体俯卧位与仰卧位的治疗精度分别为0.81和0.72 mm,均满足ACCURAY公司提供的0.90 mm的治疗标准,两者治疗精度仅差0.09 mm,可认为头颈模体颅骨追踪俯卧位与仰卧位具有同等的照射精度。结论:当患者无法进行仰卧位颅骨追踪射波刀治疗时,可以采用俯卧位颅骨追踪方式进行治疗。     

碳纤维体位固定板对椎体转移瘤放射治疗剂量的影响

目的 研究碳纤维体位固定板的透射系数及对椎体转移瘤放射治疗剂量的影响。方法 CT定位机下扫描碳纤维体位固定板，计算体位固定板在不同角度下的衰减系数，并与相同条件下的实测体位固定板衰减系数比较，分析放射治疗计划系统的准确性；另选择10例椎体转移瘤患者，其中男性5例，女性5例；年龄50～76岁，中位年龄65岁；病灶均位于双肾之间椎体上。在不勾画体位固定板的CT图像上设计无板计划，无板计划完成后将此计划移植到勾画体位固定板的CT图像上，并进行剂量计算，比较无板计划、有板计划靶区和危及器官(OAR)的剂量学差异。结果 体位固定板在不同机架角度下的实际衰减系数为0.966～0.995，放射治疗计划系统计算得到的体位固定板的衰减系数与实际测量得到的衰减系数偏差在0.62%以内；对于椎体转移瘤计划，体位固定板勾画参与剂量计算后，靶区的受照剂量明显降低，平均降低2%左右。对于靶区的适形性指数(CI)、均匀性指数(HI)，体位固定板的勾画会导致靶区的CI显著降低，差异有统计学意义(0.849±0.051 vs 0.760±0.037。P<0.05)，而对HI影响不大，差异无统计学意义(P>0...     

影像增强剂对食管癌边缘靶区剂量的影响

目的:研究调强放射治疗中使用影像增强剂后靠近心脏及胸主动脉等血流丰富组织的食管癌边缘靶区的剂量是否会降低,是否会出现欠量照射的情况。方法:选取20例食管癌患者病例,在相同体位下进行平扫及增强CT扫描,在增强CT上完成靶区勾画及调强治疗计划设计。使用两种方法进行对比,方法（1）:在增强及平扫CT上确定PTV & 5 mm Aorta和PTV & 5 mm Heart两个边缘靶区,然后进行图像配准并将治疗计划移植到平扫CT上计算剂量,对比上述两个边缘靶区在增强及平扫CT中剂量的变化。方法（2）:因为增强和平扫CT是在不同时间点扫描的,配准时两幅图像之间会存在一定差异,为了避免体位偏差的影响,使用合成CT与增强CT对比。所谓合成CT,即在复制的增强CT中将心脏、胸主动脉等血流丰富组织的CT值人工修改为平扫CT的平均CT值,操作过程与方法（1）相同,仍然观察上述两个边缘靶区的剂量变化。实验中也对比了其它组织器官在平扫与增强CT中剂量的变化。结果:方法（1）和方法（2）均显示PTV & 5 mm Aorta和PTV & 5 mm Heart两个边缘靶区剂量有所增加,其中方法（1）中两个边缘靶区的剂量分别增加1.28%（P<0.01）和1.64%（P<0.01）,方法（2）中分别增加0.41%（P<0.01）和0.83%（P<0.01）;正常组织器官（心脏、肺、脊髓等）剂量也有所增加,但均在临床可接受范围以内。结论:使用影像增强剂后靠近心脏及胸主动脉等血流丰富组织的食管癌边缘靶区剂量有所增加,不会出现欠量照射情况。     

X线下梨状隐窝下极位置测量及其临床意义

目的：观察梨状隐窝下极位置的动态变化,为临床置入高位食管内支架提供解剖学标志.方法：随机、自愿的原则对257例健康体检志愿者,在胃肠造影机下口服钡剂进行咽腔及食管造影,分别摄直立仰头位、平头位、低头位和仰卧仰头位咽腔食管造影片;通过X线片测量梨状隐窝下极与椎体相对位置.结果：直立仰头位梨状隐窝下极83.9%位于C4、C5椎体水平;直立平头位梨状隐窝下极75.9%在C5和相邻椎间盘水平;直立低头位梨状隐窝下极71.1%位于C5下1/3和C6水平;仰卧仰头位梨状隐窝下极位置79.7%位于C4和C5椎体水平.结论：临床上放置高位食管内支架时,梨状隐窝下极比椎体作为解剖学标志推断食管入口的位置更加合理、准确.     

Influence of the mediastinum on the measurement of esophageal pressure and lung compliance in man

Summary The influence of mediastinal organs on esophageal pressure was estimated in man from the variations of esophageal elastance and amplitude of the cardiac oscillations. From the simultaneous measurements of both parameters and of esophageal pressure at different lung volumes and levels in the esophagus, in the sitting and supine positions, using a 3 and 10 cm long ballon, at rest and during exercise, it was concluded: 1. The difference in measured pulmonary compliance with posture is mainly due to a mediastinal artifact, acting primarily at high lung volumes in the sitting position. In the supine position mediastinal loading is more pronounced but does not vary with lung volume (between 10 and 90% of vital capacity). 2. The vertical esophageal pressure gradient is more pronounced in the lower half of the esophagus. It is probably estimated correctly at that level but underestimated at higher levels. Pressure irregularities observed along the esophagus in the supine position are due to local actions of mediastinal organs. 3. The difference in pressure obtained with balloons of different size can be attributed to the influence of the elastic properties of the esophageal wall, provided one takes into account the vertical pressure gradient, and to shifts in the site of pressure recording in the longer balloon. 4. The increase in pressure without change of pulmonary compliance observed during exercise is also a mediastinal artifact. 5. Extrapolation of esophageal pressure towards zero balloon volume successfully corrects for the influence of posture on pulmonary compliance. However, this procedure does not allow for an estimation of intrathoracic pressure in the presence of a marked mediastinal compression effect.This work was supported by a grant of the High Authority of the European Community for Coal and Steel.     

Dynamic otolith stimulation improves the low frequency horizontal vestibulo-ocular reflex

Summary The horizontal vestibulo-ocular reflex was measured electrooculographically in four cats during sinusoidal rotations in the dark at frequencies from 0.01 Hz to 1.0 Hz in five body orientations. Vertical axis rotations in the prone and supine positions were used to stimulate horizontal canals only. Horizontal axis rotations, with the cat on the left or right side or nose down (pitched 90° from prone) were used to stimulate horizontal canal plus otolith organs. At frequencies below 0.05 Hz the horizontal vestibulo-ocular reflex produced by horizontal canal plus otolith stimulation showed a more accurately compensatory response than the horizontal vestibuloocular reflex produced by horizontal canal stimulation alone. Canal plus otolith horizontal vestibulo-ocular reflex gain and phase remained relatively constant across all frequencies, while the horizontal vestibulo-ocular reflex gain and phase from orientations involving canal stimulation alone changed dramatically as rotation frequency decreased. In addition, the reflex in the supine position showed gain decreases and phase advances at higher frequencies than in the prone position.     

Esophageal stripping creates a clear operative field for lymph node dissection along the left recurrent laryngeal nerve in prone video-assisted thoracoscopic surgery

We describe a 54-year-old man in whom esophageal carcinoma was diagnosed and who underwent video-assisted thoracoscopic surgery of the esophagus (VATS-E) in the prone position. Initially, the patient was fixed in a semiprone position, from which he could be rotated to a prone or left lateral position. Four ports were inserted, and then the patient was rotated to the prone position. Once the patient was prone, gravity caused the lung to move downwards. Next, the chest cavity was inflated with a CO(2) insufflation pressure of 6 mm Hg. Esophagectomy was then performed, and the lymph nodes in the middle and lower mediastinum and along the right recurrent laryngeal nerve were dissected. In the left upper mediastinum, lymph node dissection was performed after the residual esophagus was stripped. Stripping of the residual esophagus created sufficient working space and a clear operative field for lymph node dissection. VATS-E in the prone position has achieved remarkable results in Japan. It allows a clear operative view of the middle and lower mediastinum, but the working space in the upper mediastinum is limited. Our results indicate that esophageal stripping in prone VATS-E allows for safe and straightforward lymph node dissection along the left recurrent laryngeal nerve. Our technique overcame the difficulties usually encountered with this type of lymph node dissection.     

基于扇形束CT研究不同固定体位下宫颈癌术后放疗中膀胱体积改变对膀胱和小肠受照剂量的影响

目的:利用扇形束CT（FBCT）探讨宫颈癌术后放疗患者在不同固定体位下,膀胱体积的改变对膀胱、小肠的剂量学影响。方法:选取在中山大学肿瘤防治中心接受术后放疗的宫颈癌患者共22例,其中俯卧位固定患者10例,仰卧位固定患者12例,每次治疗前使用联影直线加速器uRT-linac 506c进行kV级FBCT,在放疗计划系统中对平移校正后的FBCT图像完成智能勾画,并复制原计划参数进行剂量计算。分析患者放疗过程中的膀胱体积变化趋势以及膀胱体积改变对膀胱和小肠受照剂量的影响。结果:22例患者在放疗过程中分次间膀胱体积与原计划膀胱体积均有不同程度的变化,且随着治疗进程,涨尿能力总体呈减弱趋势。仰卧位固定患者膀胱V45改变与膀胱体积变化率呈低度负相关（r=-0.431）,膀胱V40、V30改变与膀胱体积变化率呈中度负相关（r=-0.651、r=-0.780）,小肠V45、V40改变与膀胱体积变化率呈中度负相关（r=-0.701、r=-0.794）,小肠V30改变与膀胱体积变化率呈高度负相关（r=-0.871）。而俯卧位固定患者膀胱V30改变与膀胱体积变化率呈低度负相关（r=-0.306）,小肠V45改变与膀胱体积变化率呈低度负相关（r=-0.336）,小肠V40、V30改变与膀胱体积变化率呈中度负相关（r=-0.505、r=-0.589）。结论:宫颈癌术后放疗患者治疗过程中分次间的膀胱体积与计划时的膀胱体积较难保持一致。相比于俯卧位固定,仰卧位固定患者的膀胱体积变化对其膀胱及小肠受照剂量的影响更大。     

Origin of orientation-dependent asymmetries in vestibulo-ocular reflexes evoked by caloric stimulation

A caloric stimulus evokes primarily a horizontal vestibulo-ocular reflex (VOR) when subjects are in a supine or prone orientation with the horizontal semicircular canal plane oriented vertically. In both monkeys and humans, the magnitude of VOR eye movements is greater in the supine than in the prone orientation, indicating that some factor or factors, other than the conventionally accepted convective stimulation of the horizontal canals, contributes to the generation of the VOR. We used long-duration caloric irrigations and mathematical models of canal-otolith interactions to investigate factors contributing to the prone/supine asymmetry. Binaural caloric irrigations were applied for 7.5 or 9.5 min with subjects in a null orientation with horizontal canals in the earth-horizontal plane (control trial), or with the subject's pitch orientation periodically changing between null, supine, and prone positions with each orientation held for 30 s (caloric step trial). The control trial responses identified a small response attributable to a direct thermal effect on vestibular afferent activity that accounted for only 15% of the observed prone/supine asymmetry. We show that the gravito-inertial force resolution hypothesis for sensory integration of canal and otolith information predicts that the central processing of canal and otolith information produces an internal estimate of motion that includes both a rotational motion component and a linear acceleration component. These components evoke a horizontal angular VOR and linear VOR, which combine additively in the supine orientation, but subtract in the prone orientation, thus accounting for the majority of the observed prone/supine asymmetry.     

Changes in systemic and pulmonary blood flow distribution in normal adult volunteers in response to posture and exercise: a phase contrast magnetic resonance imaging study

Hemodynamics are usually evaluated in the supine position at rest. This is only a snapshot of an individual’s daily activities. This study describes circulatory adaptation, as assessed by magnetic resonance imaging, to changes in position and exercise. Phase contrast magnetic resonance imaging of blood flow within systemic and pulmonary arteries and veins was performed in 24 healthy volunteers at rest in the prone and supine position and with bicycle exercise in the supine position. No change was seen in systemic blood flow when moving from prone to supine. Exercise resulted in an increased percentage of cardiac output towards the lower body. Changes in position resulted in a redistribution of blood flow within the left lung—supine positioning resulted in decreased blood flow to the left lower pulmonary vein. With exercise, both the right and left lower lobes received increased blood flow, while the upper lobes received less.     

CT结肠成像技术扫描体位的优化

目的探讨不同部位的结直肠癌病变或结直肠癌术后吻合口显示清晰程度与扫描体位（仰卧位/俯卧位）的关系,为优化CT结肠成像（CTC）技术提供理论依据。方法选择32例临床病理确诊为结直肠癌患者,其中男性22例,女性10例;年龄30～73岁,平均年龄50.6岁。行CTC检查,体位采用仰卧位及俯卧位,将CTC结果与纤维肠镜和手术病理结果对照。同时有20例术后吻合口（直肠为保肛患者）患者获得复查。结果 52例次患者中,病灶及吻合口位于直肠27例次,肛管3例次,乙状结肠9例次,降结肠3例次,横结肠4例次,升结肠6例次,均为单发病灶。位于直肠与乙状结肠的病变或吻合口：直肠25/27（92.59%,χ2=32.72,P﹤0.05）,乙状结肠9/9（100%,χ2=8.42,P﹤0.05）。俯卧位上肠管充气明显,病变显示清晰,优于仰卧位,差异具有统计学意义;位于横结肠的病变或吻合口4/4（100%,χ2=4.5,P﹤0.05）,仰卧位肠管充气明显,病变显示清晰,优于俯卧位,差异具有统计学意义。升降结肠病变或吻合口在仰卧位9/9（100%）及俯卧位9/9（100%）上肠管充气效果相同,均显示清晰,差异无统计学意义。肛管癌在仰卧位（0/3）及俯卧位（0/3）上均显示欠佳,由于病例数少,不具有统计学意义。结论 CTC中不同体位上不同位置的结直肠肠管充气效果不同,根据病变或吻合口的位置,采取最佳单体位,可使患者接受的射线剂量减半,而肠管的充气效果最佳,有利于显示病变及判定吻合口有无复发。     

Morphometric analysis of the thoracolumbar and lumbar pedicles,anatomo-radiologic study

The geometric properties of 380 vertebral pedicles, ranging from T6 to L5, were analysed. Measurement were made directly from the specimens as well as from roentgenograms. The parameters considered were the horizontal and vertical pedicle diameters, pedicle angles in the transverse and sagittal planes, and the transverse and anteroposterior widths of the spinal canal and vertebral body. In addition, the length of the pedicle and the length of the pedicle including the vertebral body to the anterior cortex were measured along the pedicle axis and in a line parallel to the midline of the vertebral body. The smallest horizontal and vertical pedicle diameters were found at vertebral levels from T6 to T10. The correlation between pedicle widths and screw dimensions is obvious. In the transverse plane, the pedicle angle diverged from the vertebral body at all levels, except at T12. In the sagittal plane, the pedicles were angled cephalad from T6 to L3 and slightly caudally at L5. Knowledge of the length of the pedicle to the anterior vertebral body cortex is very important for safe screw purchase. At all levels, with the exception of T12, this length was found to be significantly greater along the pedicle axis than along a line parallel to the midline of the vertebral body.