Treatment Planning With Unflattened as Compared to Flattened Beams for Bilateral Carcinoma of the Breast

Aim: To evaluate the plan quality of 6MV unflattened (UFB) and flattened beam (FB) photon energy using AAA dose calculation algorithms for volumetric arc therapy. Materials and Methods: Plans were generated for bilateral carcinoma of breast and the dose prescribed was 50.4Gy in 28 fractions. Two different plans were made for each patient using 6MV FB and 6MV UFB. Dose calculations were performed on an AAA dose calculation algorithm. Plans were generated on Eclipse TPS and were capable of being delivered with a true beam STx linear accelerator. The homogeneity index (HI), conformity index (CI), normal tissue integral dose (NTID), and effect of low dose volume on normal tissue and monitor units (MU) were noted. Results: All the plans were clinically acceptable. The HI and CI of 6MV UF rapid arc (RA) plans were higher than with the 6MV FB plan (1.16±0.05 and 0.12±0.00 respectively). There was no appreciable difference observed in Organ at risk (OAR) doses. The mean NTID and low dose volume were significantly low with 6MV RA UFB as compared to FB. 6MV RA UFB required a 35% higher MU than with the 6MV RA plan (p<0.05). Conclusion: RA plans generated with UFB on Eclipse TPS achieved target volume coverage and preserved OAR’s essentially similar to 6MV RA FB plans. However RA plans generated in Varian Eclipse of UFB were superior with respect to mean NTID and low dose volumes in normal tissue.     

CBCT分析乳腺癌保乳术后瘤床钛夹标记位置变化

目的 分析乳腺癌保乳术后瘤床钛夹标记位置的变化及其影响因素。 方法 回顾分析 2016年间收治的 14例乳腺癌保乳术后放疗患者的锥形束CT影像,分别测量胸壁以及每个钛夹在放疗过程中的误差。将钛夹的位移与钛夹的相对位置、乳腺体积、胸壁切线垂直距离以及乳腺最大厚度等因素进行Pearson相关性分析。 结果 胸壁系统误差和随机误差在左右、头脚、前后方向分别为4.42、3.44、5.13 mm和3.55、3.07、4.54 mm。钛夹相对胸壁有较大的位移,主要集中在左右方向,最大系统误差、随机误差分别为4.39、2.42 mm。钛夹位移与乳腺体积、乳腺的厚度无明显相关(P>0.05)。钛夹头脚方向的相对位置与最下、最外、最前与最后钛夹的位移相关(P<0.05)。最上钛夹的近胸壁组与远胸壁组的位移差异有统计学意义(P=0.02)。 结论 乳腺癌放疗中采用真空垫进行体位固定时存在较大的摆位误差,钛夹在放疗过程中存在较大的位移,不推荐使用同步加量照射技术;缺乏良好的固定可能是钛夹存在较大位移的主要影响因素。     

医用直线加速器机载影像系统QC图像定量评估方法研究

目的 实现医用直线加速器机载影像系统QC图像质量的定量分析。方法 使用医科达iViewGT和XVI影像系统以及瓦里安aS1000和OBI影像系统,分别进行EPID的MV平片和CBCT的KV平片及三维影像质量检测。所用体模为Las Vegas、TOR18FG、Catphan504。通过对采集图像分析得到MV平片、KV平片及三维影像各个图像指标的定量结果。结果 给出了iViewGT和aS1000两种EPID对比度分辨率,并用定量值表示;给出了XVI、OBI系统KV影像验证片对比度分辨率定量结果,以及用以表征空间分辨率的MTF曲线。对XVI、OBI系统三维影像下噪声、均匀性、CT值一致性、对比度分辨率进行了定量分析,给出了用以表征空间分辨率的MTF曲线。结论 给出了一套完整的基于常用模体定量检测EPID和CBCT图像质量方法,为建立IGRT下规范图像质量QC制度提供了非常好的参考价值。     

Determination of Initial Beam Parameters of Varian 2100 CD Linac for Various Therapeutic Electrons Using PRIMO

The aim of the present research was to establish primary characteristics of electron beams for a Varian 2100C/D linear accelerator with recently developed PRIMO Monte Carlo software and to verify relations between electron energy and dose distribution. To maintain conformity of simulated and measured dose curves within 1%/1mm, mean energy, Full Width at Half Maximum (FWHM) of energy and focal spot FWHM of initial beam were changed iteratively. Mean and most probable energies were extracted from validated phase spaces and compared with related empirical equation results. To explain the importance of correct estimation of primary energy on a clinical case, computed tomography images of a thorax phantom were imported in PRIMO. Dose distributions and dose volume histogram (DVH) curves were compared between validated and artificial cases with overestimated energy. Initial mean energies were obtained of 6.68, 9.73, 13.2 and 16.4 MeV for 6, 9, 12 and 15 nominal energies, respectively. Energy FWHM reduced with increase in energy. Three mm focal spot FWHM for 9 MeV and 4 mm for other energies made proper matches of simulated and measured profiles. In addition, the maximum difference of calculated mean electrons energy at the phantom surface with empirical equation was 2.2 percent. Finally, clear differences in DVH curves of validated and artificial energy were observed as heterogeneity indexes were 0.15 for 7.21 MeV and 0.25 for 6.68 MeV. The Monte Carlo model presented in PRIMO for Varian 2100 CD was precisely validated. IAEA polynomial equations estimated mean energy more accurately than a known linear one. Small displacement of R50 changed DVH curves and homogeneity indexes. PRIMO is a user-friendly software which has suitable capabilities to calculate dose distribution in water phantoms or computerized tomographic volumes accurately.     

锥形束CT与根尖牙片诊断牙根折裂的对比分析

目的:对比分析锥形束CT与根尖牙片在根折诊断中的诊断价值。方法:选取经临床拔牙或外科探查证实的35 例(37个患牙)根折裂患者,均作CBCT和根尖牙片检查,对比分析图像。结果:37个患牙中,CBCT在检出根折35个,根尖牙片检出折裂线16个。结论:CBCT检知牙根折裂的准确率明显高于根尖牙片,能清晰显示根折位置及类型,对临床制定根折治疗方案有重要应用价值。     

锥形束CT辅助美学区种植评价唇侧骨量的应用研究

目的应用锥形束CT(CBCT)比较拔牙后即刻种植与延期种植术后1年唇侧骨量变化的差异,评价CBCT在美学区种植唇侧骨量的诊断价值。 方法选择2009年6月至2013年6月上颌前牙区完成单颗种植的患者22例,共22颗种植体,拔牙后即刻种植与延期种植各11颗。分别在种植术前1周、术后即刻与术后1年进行CBCT影像学检查,根据设计的测量位点评价唇侧骨高度与骨厚度变化,采用SPSS 13.0软件包对测量数据进行统计学分析,采用配对t检验比较所有病例术后即刻与术后1年唇侧骨高度与骨厚度的变化。 结果即刻种植术后1年唇侧牙槽嵴高度变化差异有统计学意义(t=3.316,P=0.009),延期种植差异无统计学意义(t=2.073,P=0.068);两组术后1年唇侧骨厚度在距离种植体基台连接处1 mm处(t=2.369,P=0.042)与种植体中点处(t=3.474,P=0.007)差异均有统计学意义,在距离种植体底1 mm处差异均无统计学意义(t=1.596,P=0.145)。 结论CBCT可用于美学区种植唇侧骨量的价值诊断,可以准确评价拔牙后即刻种植与延期种植术后1年唇侧骨量变化。     

两种微动力系统在上颌埋伏多生牙拔除术中应用的比较

目的通过对比超声骨刀与涡轮手机去骨法拔除上颌埋伏多生牙的手术效果,探讨更为方便、安全、有效的拔牙方法。 方法选取2013—2017年中山市人民医院口腔颌面外科拔除上颌埋伏多生牙且符合纳入标准的患者150例（共计190颗多生牙）,通过抽签的方法随机分两组。术前均完善锥形束CT（CBCT）检查以定位埋伏多生牙,采用局部浸润麻醉方式,选择合适的切口入路,实验组采取超声骨刀去骨法拔牙,对照组采取涡轮反角手机去骨法拔牙。采用视觉模拟评分法（VAS）量化患者术后疼痛情况,采用SPSS 20.0软件以独立样本的t检验法对两组患者以及年满12周岁以上患者的手术时间、术后疼痛值进行对比分析。 结果患者术后疼痛的VAS值范围为0 ~ 10（0为完全无痛,10为最为剧烈的疼痛）,实验组VAS均值为4.2 ± 1.5,低于对照组的5.2 ± 1.6,差异有统计学意义（t=-4.072,P<0.001）。而对于12岁以上患者的疼痛VAS值分析,实验组均值为4.2 ± 1.5,亦低于对照组的5.1 ± 1.6,差异有统计学意义（t=-2.866,P= 0.005）。手术时间平均值,实验组为（48 ± 6）min,低于对照组的（51±8）min,差异有统计学意义（t=-3.014,P= 0.003）。而对于12岁以上患者的手术平均时间分析,实验组均值为（46 ± 6）min,亦低于对照组的（49 ± 7）min,但差异无统计学意义（t=-0.901,P= 0.060）。 结论采用CBCT引导下超声骨刀拔牙法拔除上颌埋伏多生牙,疼痛少、时间短、舒适性好,是一种值得推广的拔牙方法。     

Imaging for percutaneous left atrial appendage closure

Percutaneous left atrial appendage (LAA) closure is increasingly performed worldwide as an alternative to long‐term oral anticoagulation, especially for patients who are considered ineligible for anticoagulation. This is a complex procedure with success that hinges upon good understanding of the LAA and surrounding structures anatomy. Multimodality imaging can provide important three‐dimensional appreciation of the LAA anatomy, which facilitates procedural safety and success. Thus, proceduralists and imagers involved with LAA closure should have good comprehension of such imaging modalities (cardiac CT angiography, transesophageal echocardiography, and/or intracardiac echocardiography) prior to embarking on this procedure. © 2016 Wiley Periodicals, Inc.