千伏级锥形束kV-CBCT在鼻咽癌调强放疗摆位误差的研究

目的 应用机载千伏级锥形束CT (CBCT)分析鼻咽癌调强放射治疗的摆位误差。方法 本研究选取32例IM-RT的鼻咽癌患者,治疗过程中每周一次治疗前行CBCT扫描,获取的CBCT图像和CT图像匹配后得出三维方向上的平移误差。结果 摆位误差绝对值分别为左右(1.50±0.87) mm,头脚(1.59±0.87) mm,腹背(1.95±0.99) mm,根据van Herk公式计算得到各个方向的PTV外扩值分别为左右2.9 mm、头脚4.5 mm、腹背3.1 mm。结论 建议PTV不均匀外扩;腹背方向摆位误差较左右、头脚方向大,在摆位中应注意误差大的方向,提高摆位的准确性。     

图像引导调强放射治疗胸腹部肿瘤的摆位误差分析

目的 研究胸腹部肿瘤中应用图像引导调强放射治疗(Image Guided Radiation Therapy,IGRT)。方法 观察对象选择2020年2～4月广东省农垦中心医院收治的20例胸腹部肿瘤患者,全部患者接受瓦里安VitalBEAM IGRT加速器治疗,并经由锥形束CT(Cone beam CT,CBCT)技术获得线性摆位误差[左右(x)、头脚(y)、前后(z)]以及旋转摆位误差[u(对应x)、v(对应y)、w(对应z)],展开摆位误差分析。结果 ①20例患者采集CBCT共441次,各方向的平均摆位误差以“系统误差±随机误差”代表,分别为：x轴是(0.16±0.08)cm,y轴是(0.09±0.14)cm、z轴是(-0.03±0.13)cm、u轴是0.77°±0.26°、v轴是-0.21°±0.28°、w轴是0.21°±0.18°;②x方向的误差最小,而y方向的误差最大;x方向、y方向、z方向的外扩值为0.61cm、1.12cm、0.69cm。结论 在胸腹部肿瘤治疗中应用IGRT,可在线纠正摆位误差,做到低损伤、高精度治疗;且为避免摆位误差影响,当计算临床耙体积(Cli...     

不同配准方式对鼻咽癌螺旋断层调强放射治疗患者摆位误差的影响

目的探讨在高能X射线计算机体层摄影(MVCT)引导下螺旋断层调强放射治疗中两种自动图像配准技术对鼻咽癌放射治疗患者摆位误差的影响。方法随机选取2016年10月至2017年10月采用螺旋断层调强放射治疗技术进行调强放射治疗的鼻咽癌患者22例,每例患者治疗前均行MVCT扫描,将扫描获取的MVCT图像与定位图像行骨配准、骨与软组织配准,分别记录患者左右(X轴)、头脚(Y轴)、腹背(Z轴)方向的线性误差以及绕此3个方向形成的旋转误差(U、V、W)这6个方面的配准数据,分析两种配准方式之间的差异。结果 22例患者共150组MVCT扫描图像数据,所选数据符合正态分布。其中骨配准在X轴、Y轴、Z轴方向的平移误差与绕此3方向的旋转误差分别为(0.946±1.701)mm、(0.937±1.059)mm、(0.077±1.161)mm与(-0.127±1.201)°、(-0.217±1.104)°、(-0.280±0.897)°;骨与软组织配准在X轴、Y轴、Z轴方向的平移误差与绕此3方向的旋转误差分别为(0.920±1.397)mm、(1.045±1.167)mm、(0.386±1.212)mm与(-0.156±1.079)°、(-0.142±0.648)°、(-0.169±0.685)°。将6个方向的摆位误差计量数据进行配对t检验,骨配准、骨与软组织配准两种配准方式在Y轴、Z轴方向上的平移误差比较,差异有统计学意义(P<0.05);其他4个方向的摆位误差比较,差异均无统计学意义(P>0.05)。结论鼻咽癌患者进行螺旋断层调强放射治疗时,为降低患者摆位误差,建议首选骨配准,必要时辅以手动微调直至满意为止。     

放射治疗中真空垫摆位的技术改进

目的：提高放射治疗中真空垫摆位的精度。方法将200例使用真空垫进行摆位的患者随机分为两组，传统组（100例）使用传统方法进行摆位，改进组（100例）使用改进过的方法进行摆位，用锥形束CT（CBCT）系统分析两组首次摆位时的误差；将传统组再随机分为两组，一组（50例）定时对真空垫抽真空，另一组（50例）“适时”对真空垫抽真空，用CBCT系统分析两组第15次摆位时的误差。结果与传统组相比，改进组在X、Y、Z轴方向上的摆位误差均有明显改善（P＜0.05）；与“适时”抽气组相比，定时抽气组在X、Z轴方向摆位误差有明显改善（P＜0.05）。结论真空垫摆位的技术改进有效提高了摆位精度。     

利用锥形束CT图像分析胸部调强放疗的摆位误差

目的 应用医科达Synergy IGRT机载KV-CBCT校正胸部调强放疗摆位误差,分析校正前后摆位误差的变化.方法 选取2012年1月至2012年5月在我科应用医科达Synergy系统治疗的胸部患者15例.每位患者在疗程中使用频率为7～20次的(Cone Beam CT,CBCT)扫描,共190次.采集的X射线容积图像(XⅥ)与计划图像的靶中心配准,获得靶中心x、y和z方向的平移误差和3个轴向的旋转误差,采用机载六维治疗床系统(HexaPODTMevo system)对误差进行校准,分析误差及其分布规律.结果 摆位误差在x、y和z轴上分别为(-0.43 ～0.35)cm、(-0.46 ～0.15)cm、(-0.23～0.40)cm和旋转轴上的分别为(-1.7 ～1.8)°、(-2.1 ～2.8)°、(-2.8～1.4)°校正后的摆位误差在x、y和z轴上分别为(-0.26 ～0.18)cm、(-0.24 ～0.25)cm、(-0.19～0.16)cm和旋转轴上的分别为(-0.6 ～0.8)°、(-0.9 ～0.9)°、(-1～0.7)°校正后的系统误差和随机误差均低于校正前.根据van Herk等摆位扩边公式Mptv =2.5Σ+0.7σ,计算得出X、Y、Z方向的Mptv值分别为X为0.36 cm Y为0.66 cm Z为0.45 cm.如果每次放射治疗均进行在线图像引导校正,在实际应用中Mptv值为X为0.23 cm Y为0.28 cm Z为0.20 cm.结论 通过CBCT对放疗摆位中出现的线性误差和旋转误差进行校正,可以缩小系统误差和随机误差,基于CBCT图像分析的在线校正方法能减少该摆位误差,并有助于确定合适的临床靶区外放.从而缩小CTV-PTV的摆位扩放(Margin),提高放射治疗的精确性,降低周围正常组织剂量受量,保护正常组织,降低副反应.     

CT模拟机及CBCT在头颈部肿瘤图像引导放射治疗中的首次摆位误差

目的在采用图像引导放射治疗的头颈部肿瘤患者中,对比分析CT模拟机与千伏级锥形束CT所获得的首次摆位误差。方法选取2019年4—8月于福建医科大学附属第一医院接受图像引导放射治疗的头颈部肿瘤患者106例,将患者分别在CT模拟机与Varian Trilogy直线加速器进行图像引导放射治疗的首次摆位,然后将采集的图像分别与计划CT进行图像配准比对,从而获得两组在左右(LR)、头脚(SI)和前后(AP)3个方向上的首次摆位误差,分别记为CT模拟机组和锥形束CT(CBCT)组,采用配对t检验比较两组数据。结果CT模拟机组和CBCT组在LR、SI、AP方向的首次摆位误差分别为(0.02±1.04)、(-0.04±1.21)、(0.13±0.88)mm和(-0.13±0.93)、(-0.06±0.81)、(-0.06±0.73)mm,差异均无统计学意义(P>0.05)。结论在CT模拟机上对患者进行首次摆位之后,就无需在直线加速器上再进行首次摆位,以提高直线加速器的使用效率。     

千伏级锥形束断层扫描验证胸腹部肿瘤容积旋转调强放射治疗摆位误差的准确度

目的 采用千伏级锥形束断层扫描(kV-CBCT)量化分析胸腹部肿瘤容积旋转调强放射治疗(VMAT)摆位误差的准确度.方法 选取2017年3月至2019年9月于福建医科大学附属协和医院放疗科行胸腹部VMAT的78例患者作为研究对象,于治疗前行kV-CBCT获取实时摆位3D扫描验证图像,并采用灰度自动配准结合人工核对的方法...     

锥形束CT图像引导系统在放射治疗中的应用

目的：研究锥形束CT（CBCT）图像引导系统在精确放射治疗中提高摆位的精度,减少摆位的不确定性的作用。方法：对头颈部肿瘤患者（30例）和胸部肿瘤患者（40例）用CBCT扫描,其中头颈部肿瘤患者扫描90次,胸部肿瘤患者扫描113次,统计患者前后、头脚及左右方向的摆位偏差。结果：对于头颈部肿瘤患者前后方向的最大偏差值为6 mm,3个方向中〉3 mm偏差的均在10%以下;对于胸部肿瘤患者的头脚方向摆位误差最大,〉5 mm的达21.51%。前后方向的误差≤5 mm,左右方向〉5 mm的为4.53%。结论：采用CBCT图像引导系统对患者体位实时修正,极大的提升了放射治疗的精度和疗效。相对于电子射野影像验证系统（EPID）,CBCT对患者的累积剂量的影响更小,图像分辨率更高,图像匹配更精确,但是和普通螺旋CT相比,其分辨率和扫描范围还需要更进一步的提高。     

胸段食管癌放射治疗首次摆位误差分析研究

目的:利用锥形束CT(CBCT)分析不同分段食管癌患者放射治疗首次摆位误差。方法:在首次治疗前行CBCT验证,当平移误差<3 mm且旋转误差<3°时实施治疗;当平移误差>3 mm,<5 mm,在线纠正,再次行CBCT扫描,如果误差<3 mm实施治疗,否则需要重新摆位,重新验证。利用SPSS软件分析胸上段、胸中段及胸下段食管癌摆位误差。结果:胸上段、胸中段及胸下段食管癌首次摆位误差合格率分别为82.62%、79.59%和75.41%,再次摆位共8例,占比分别为2.94%、0.68%和6.56%。胸上段X轴、Y轴及Z轴误差与胸中段、胸下段误差差异无统计学意义。胸中段X轴、Z轴与胸下段治疗误差数据差异有统计学意义(t=-2.33,t=-4.46;P<0.05)。结论:在首次摆位中胸下段食管癌摆位误差略大于胸上段和胸中段食管癌,必要时可通过在线纠正和重新摆位减少摆位误差,提高治疗精度。     

应用OBI系统分析鼻咽癌调强放疗的摆位误差

目的:应用机载影像系统(OBI)分析鼻咽癌调强放射治疗的摆位误差。方法:应用Varian-21EX医用直线加速器治疗38例鼻咽癌患者。在首次调强放射治疗前应用OBl系统获取锥形束断层扫描(CBCT)图像,前3 d每天1次,以后每周1次,将CBCT图像和计划CT图像匹配得出两者间平移和旋转误差。结果:首次扫描获得的平均误差分别为左右(-0.49±1.90)mm,头脚(0.64±1.36)mm,前后(-0.57±1.78)mm;旋转误差为(0.05±0.11)°。经首次校正后其余各次摆位误差减小为左右(0.30±1.01)mm,头脚(0.12±0.92)mm,前后(0.47±1.05)mm;旋转误差(-0.02±0.03)°。结论:应用OBI系统验证摆位误差可以提高摆位精度,减少周围正常组织的照射。对于鼻咽癌调强放疗,临床靶体积(CTV)到计划靶体积(PTV)的外放边界约为2 mm。     

Toxicity and efficacy of three dose-fractionation regimens of intensity-modulated radiation therapy for localized prostate cancer

Outcomes of three protocols of intensity-modulated radiation therapy (IMRT) for localized prostate cancer were evaluated. A total of 259 patients treated with 5-field IMRT between 2005 and 2011 were analyzed. First, 74 patients were treated with a daily fraction of 2.0 Gy to a total of 74 Gy (low risk) or 78 Gy (intermediate or high risk). Then, 101 patients were treated with a 2.1-Gy daily fraction to 73.5 or 77.7 Gy. More recently, 84 patients were treated with a 2.2-Gy fraction to 72.6 or 74.8 Gy. The median patient age was 70 years (range, 54–82) and the follow-up period for living patients was 47 months (range, 18–97). Androgen deprivation therapy was given according to patient risk. The overall and biochemical failure-free survival rates were, respectively, 96 and 82% at 6 years in the 2.0-Gy group, 99 and 96% at 4 years in the 2.1-Gy group, and 99 and 96% at 2 years in the 2.2-Gy group. The biochemical failure-free rate for high-risk patients in all groups was 89% at 4 years. Incidences of Grade ≥2 acute genitourinary toxicities were 9.5% in the 2.0-Gy group, 18% in the 2.1-Gy group, and 15% in the 2.2-Gy group (P = 0.29). Cumulative incidences of Grade ≥2 late gastrointestinal toxicity were 13% in the 2.0-Gy group at 6 years, 12% in the 2.1-Gy group at 4 years, and 3.7% in the 2.2-Gy group at 2 years (P = 0.23). So far, this stepwise shortening of treatment periods seems to be successful.     

A surveillance study of intensity-modulated radiation therapy for postoperative cervical cancer in Japan

Intensity-modulated radiation therapy (IMRT) was recently introduced to the field of gynecologic malignancies; however, its value is not yet validated. A clinical trial is in preparation to investigate the efficacy and feasibility of IMRT for postoperative cervical cancer. The object of this study was to perform a surveillance study of IMRT for post-operative cervical cancer. A questionnaire regarding the precise methods of conducting IMRT was sent to six institutions that had already introduced IMRT for post-operative cervical cancer, and the data were analyzed. Half of the institutions used static IMRT and the others used volumetric-modulated arc therapy (VMAT). Most institutions used body-immobilizing devices for patient fixation. Most institutions instructed patients to fill their bladder before undergoing planning CT or daily treatment. While one institution inserted metallic markers and another one used radio-contrast–soaked gauze to visualize the vaginal cuff, the other institutions used nothing for vaginal cuff visualization. Most institutions defined the clinical target volumes according to the Japan Clinical Oncology Group or the Radiation Therapy Oncology Group guidelines. Only one institution used a prescribed dose based on 95% of the PTV (D₉₅), while the rest used the mean dose (D_mean). This valuable information from six leading institutions will be utilized in a future prospective clinical trial.     

Utility of Smart Arc CDR for intensity-modulated radiation therapy for prostate cancer

Volumetric-modulated arc therapy (VMAT) is a widespread intensity-modulated radiation therapy (IMRT) method, however, VMAT requires adaptation of the radiation treatment planning system (RTPS) and linear accelerator (linac); these upgrades are quite expensive. The Smart Arc of Pinnacle³ (Philips), which is the software used in VMAT calculations, can select constant dose rate (CDR) mode. This approach has a low initial cost because the linac upgrade is not required. The objective of this study was to clarify the utility of CDR mode for prostate IMRT. Pinnacle³ and Clinac 21EX linac (Varian, 10 MV X-rays) were used for planning. The plans were created for 28 patients using a fixed multi-field IMRT (f-IMRT), VMAT and CDR techniques. The dose distribution results were classified into three groups: optimal, suboptimal and reject. For the f-IMRT, VMAT and CDR results, 25, 26 and 21 patients were classified as ‘optimal’, respectively. Our results show a significant reduction in the achievement rate of ‘optimal’ for a CDR when the bladder volume is <100 cm³. The total numbers of monitoring units (MUs) (average ± 1σ) were 469 ± 53, 357 ± 35 and 365 ± 33; the average optimization times were ∼50 min, 2 h and 2 h 40 min, and the irradiation times were ∼280 s, 60 s and 110 s, respectively. CDR can reduce the total MUs and irradiation time compared with f-IMRT, and CDR has a lower initial cost compared with VMAT. Thus, for institutions that do not currently perform VMAT, CDR is a useful option. Additionally, in the context of patient identification, bladder volume may be useful.     

浅析调强放射治疗对乳腺癌保乳术后患者的影响

目的 探讨调强放射治疗对乳腺癌保乳术后患者的影响。方法 选取2015年3月—2019年10月在本院接受保乳术治疗的98例乳腺癌患者作为研究对象,按随机数字表法分为观察组与对照组,每组各49例。对照组采用常规放射治疗,观察组采用调强放射治疗。比较2组疗效、计划靶区剂量学、肌钙蛋白水平、预后情况。结果 观察组疗效总有效率为83.67%,高于对照组的65.31%,差异具有统计学意义(χ2=4.350,P=0.037);观察组计划靶区V100%、V105%分别为(9.68±0.65)%、(1.03±0.06)%,分别低于对照组的(42.02±4.87)%、(24.51±2.54)%,差异具有统计学意义(t=46.076、64.691,P值均<0.001);放疗后,观察组和对照组肌钙蛋白分别为(0.116±0.012)ng/mL、(0.260±0.019)ng/mL,分别高于放疗前的(0.059±0.010)ng/mL、(0.057±0.009)ng/mL,差异具有统计学意义(P<0.05),但观察组肌钙蛋白较对照组低,差异有统计学意义(t=44.855,P<0.001);观察组的无瘤生存率为97.96%,高于对照组的83.67%,差异具有统计学意义(χ2=4.405,P=0.036)。结论 对乳腺癌保乳术后患者辅以调强放射治疗,可提高临床疗效,调节靶区照射剂量均匀性、适应性,避免心肌及其他周围组织损伤,并提高无瘤生存率,改善预后。     

前列腺癌调强放疗重复CT模拟定位的作用

目的:探讨前列腺癌调强放疗重复CT模拟定位的作用。方法:前列腺癌调强放疗首次CT模拟定位后行CT扫描,在模拟定位工作站确定靶体积中心(等中心)做体表标记。于放射治疗4周左右进行重复CT模拟定位,扫描前用激光灯核对原等中心标记,记录等中心数值后进行CT扫描。在模拟定位工作站录入记录的原等中心数值传输至治疗计划系统,与首次CT模拟定位的图像融合后进行对比分析。结果:首次CT与重复CT图像融合后测量靶区位移的平均误差左右(RL)方向为1.9mm;头脚(SI)方向为2.8mm;前后(AP)方向为3.1mm。危及器官膀胱和直肠的最大剂量分别增加0.5～3.7Gy、0.9～5.0Gy;平均剂量分别增加0.7～4.9Gy、0.6～5.4Gy;最小剂量分别增加0.3～1.3Gy、0.6～2.8Gy。结论:前列腺癌调强放疗重复CT模拟定位便于对比分析靶区和危及器官的位移和对剂量的影响,为及时调整治疗计划提供依据。     

Radiobiological model-based bio-anatomical quality assurance in intensity-modulated radiation therapy for prostate cancer

A bio-anatomical quality assurance (QA) method employing tumor control probability (TCP) and normal tissue complication probability (NTCP) is described that can integrate radiobiological effects into intensity-modulated radiation therapy (IMRT). We evaluated the variations in the radiobiological effects caused by random errors (r-errors) and systematic errors (s-errors) by evaluating TCP and NTCP in two groups: patients with an intact prostate (G_intact) and those who have undergone prostatectomy (G_tectomy). The r-errors were generated using an isocenter shift of ±1 mm to simulate a misaligned patient set-up. The s-errors were generated using individual leaves that were displaced inwardly and outwardly by 1 mm on multileaf collimator field files. Subvolume-based TCP and NTCP were visualized on computed tomography (CT) images to determine the radiobiological effects on the principal structures. The bio-anatomical QA using the TCP and NTCP maps differentiated the critical radiobiological effects on specific volumes, particularly at the anterior rectal walls and planning target volumes. The s-errors showed a TCP variation of –40–25% in G_tectomy and –30–10% in G_intact, while the r-errors were less than 1.5% in both groups. The r-errors for the rectum and bladder showed higher NTCP variations at ±20% and ±10%, respectively, and the s-errors were greater than ±65% for both. This bio-anatomical method, as a patient-specific IMRT QA, can provide distinct indications of clinically significant radiobiological effects beyond the minimization of probable physical dose errors in phantoms.     

Interfractional and intrafractional errors assessed by daily cone-beam computed tomography in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy: a prospective study

This prospective study was to assess interfractional and intrafractional errors and to estimate appropriate margins for planning target volume (PTV) by using daily cone-beam computed tomography (CBCT) guidance in nasopharyngeal carcinoma (NPC). Daily pretreatment and post-treatment CBCT scans were acquired separately after initial patient setup and after the completion of each treatment fraction in 10 patients treated with IMRT. Online corrections were made before treatment if any translational setup error was found. Interfractional and intrafractional errors were recorded in the right–left (RL), superior–inferior (SI) and anterior–posterior (AP) directions. For the translational shifts, interfractional errors >2 mm occurred in 21.7% of measurements in the RL direction, 12.7% in the SI direction and 34.1% in the AP direction, respectively. Online correction resulted in 100% of residual errors ≤2 mm in the RL and SI directions, and 95.5% of residual errors ≤2 mm in the AP direction. No residual errors >3 mm occurred in the three directions. For the rotational shifts, a significant reduction was found in the magnitudes of residual errors compared with those of interfractional errors. A margin of 4.9 mm, 4.0 mm and 6.3 mm was required in the RL, SI and AP directions, respectively, when daily CBCT scans were not performed. With daily CBCT, the margins were reduced to 1.2 mm in all directions. In conclusion, daily CBCT guidance is an effective modality to improve the accuracy of IMRT for NPC. The online correction could result in a 70–81% reduction in margin size.     

应用切片法制作静态调强挡块研究与实验

目的：通过静态调强放射新方法的研究，使得各级医院能利用现有普通放疗设备．通过增加精确定位设备和计算机放射治疗计划系统，开展静态调强放射治疗。方法：在适形放射治疗技术的基础上，提出了一种“切片”的方法，从而能利用现有简单设备制作出三维熔铅调强挡块。结果：实验和研究表明，运用该方法制作的三维熔铅调强挡块，不仅能实现靶区高剂量的形状在三维方向上与肿瘤的形状一致，而且可对照射野内剂量分布按要求的方式调整。结论：该方法简单可行，性能价格比较高，在我国各级中小医院具有良好的临床应用前景和推广意义．     

Dosimetric impact of rotational setup errors in volumetric modulated arc therapy for postoperative cervical cancer

We aimed to evaluate the impact of rotational setup errors on the doses received during postoperative volumetric-modulated arc therapy (VMAT) for cervical cancer. Overall, 121 cone-beam computed tomography (CBCT) sets from 20 patients were rigidly registered to reference computed tomography (CT) sets based on bony landmarks. The rotational setup errors (pitch, yaw and roll) were calculated. Then, 121 CT sets involving rotational setup errors were created, and the dose distribution in these CT sets were recalculated. The recalculated dosimetric parameters for the clinical target volume (CTV) and organs at risk (OAR) were compared to the reference values, and the correlation coefficients between the dosimetric parameter differences and rotational setup errors were calculated. Only the pitch setup error was moderately correlated with CTV coverage (r ≥ 0.40) and strongly correlated with V45 for the bladder (r ≥ 0.91) and V40 for the rectum, small bowel and bone marrow (r ≥ 0.91). The maximum dosimetric difference in a single fraction and overall fractions was −1.59% and −0.69% in D98 for the CTV, 11.72% and 5.17% in V45 for the bladder and −8.03% and −4.68% in V40 for the rectum, respectively. In conclusion, rotational setup errors only slightly impact dose coverage during postoperative cervical cancer VMAT. However, the pitch setup error occasionally affected the doses received by the bladder or the rectum in the overall fraction when the error was systematic. Thus, rotational setup errors should be corrected by adjusting six-degree-of-freedom (DOF) couches to reduce dosimetric differences in the OARs.