Unraveling the efficacy network: A network meta-analysis of adjuvant external beam radiation therapy methods after hepatectomy

BACKGROUND Primary liver cancer is a malignant tumor with a high recurrence rate that significantly affects patient prognosis.Postoperative adjuvant external radiation therapy(RT)has been shown to effectively prevent recurrence after liver cancer resection.However,there are multiple RT techniques available,and the differ-ential effects of these techniques in preventing postoperative liver cancer re-currence require further investigation.AIM To assess the advantages and disadvantages of various adjuvant external RT methods after liver resection based on overall survival(OS)and disease-free survival(DFS)and to determine the optimal strategy.METHODS This study involved network meta-analyses and followed the PRISMA guidelines.The data of qualified studies published before July 10,2023,were collected from PubMed,Embase,the Web of Science,and the Cochrane Library.We included relevant studies on postoperative external beam RT after liver resection that had OS and DFS as the primary endpoints.The magnitudes of the effects were determined using risk ratios with 95%confidential intervals.The results were analyzed using R software and STATA software.RESULTS A total of 12 studies,including 1265 patients with hepatocellular carcinoma(HCC)after liver resection,were included in this study.There was no significant heterogeneity in the direct paired comparisons,and there were no significant differences in the inclusion or exclusion criteria,intervention measures,or outcome indicators,meeting the assumptions of heterogeneity and transitivity.OS analysis revealed that patients who underwent stereotactic body radiotherapy(SBRT)after resection had longer OS than those who underwent intensity modulated radiotherapy(IMRT)or 3-dimensional conformal RT(3D-CRT).DFS analysis revealed that patients who underwent 3D-CRT after resection had the longest DFS.Patients who underwent IMRT after resection had longer OS than those who underwent 3D-CRT and longer DFS than those who underwent SBRT.CONCLUSION HCC patients who undergo liver cancer resection must consider distinct advantages and disadvantages when choosing between SBRT and 3D-CRT.IMRT,a RT technique that is associated with longer OS than 3D-CRT and longer DFS than SBRT,may be a preferred option.

Outcomes of External-Beam Radiation Therapy Boost with Conventional Fractionation in Cervical Cancer: A Retrospective Analysis about 133 Cases

Introduction: External-beam radiation therapy boost is a treatment option in cervical cancer when brachytherapy is not feasible. Though less effective than brachytherapy, some encouraging results have been reported from some institutions experiences. We conducted this study to assess outcomes of EBRT boost for our patients at National Institute of Oncology in Rabat. Patients and Methods: We collected data from patients treated for cervical cancer between January 2012 and December 2015. Patients, tumor and treatment characteristics were collected. Overall survival (OS), disease-free survival (DFS) and prognostic factors influencing DFS were assessed. Results: One hundred and thirty-three patients were enrolled. Median age was 52 years. Patient haemoglobin level ranged from 3.9 to 15.5 g/dl [mean: 11.2 g/dl]. Most tumors were classified stage III/IVA (63.2%) according to the FIGO classification. Regional lymph node metastases (pelvic and or para-aortic) were observed in 45.1%. Median total dose to tumor was 69.6 Gy (ranging from 66 to 70 Gy). Overall treatment time was protracted, with a median of 60 days. Most of patients received concurrent chemotherapy (94.7%) and the number of cycle ranged from 2 to 7 (median = 5). The follow-up median was 31.3 months, ranging from 6.2 to 96.8 months. At the first visit, most patients achieved complete response (80.5%). Five years OS and DFS were 47% and 44% respectively. In univariate and multivariate analysis, regional lymph nodes metastasis (presence or absence) and haemoglobin level (≤11 g/dl and >11 g/dl) were the two significant and independent prognostic factors influencing DFS (HR: 1.86;p = 0.01 for the former) (HR: 0.59;p = 0.03 for the latter). Conclusion: Our study showed that EBRT boost in conventional fractionation was an acceptable treatment option for cervical cancer unamenable to brachytherapy, especially in the two subgroups of patients that are those without pelvic and/or para-aortic lymph node metastasis and those with haemoglobin level above 11 g/dl.

Reirradiation of recurrent breast cancer with proton beam therapy:A case report and literature review

BACKGROUND Locoregional recurrence of breast cancer is challenging for clinicians,due to the various former treatments patients have undergone.However,treatment of the recurrence with systemic therapy and subsequent reirradiation of chest wall is accompanied by increased toxicities,particularly radiation-induced cardiovascular disease.Reirradiation by proton beam therapy(PBT)enables superior preservation of adjacent organs at risk as well as concurrent dose escalation for delivery to the gross tumor.This technology is expected to improve the overall outcome of recurrent breast cancer.CASE SUMMARY A 47-year-old female presented with an extensive locoregional recurrence at 10 yr after primary treatment of a luminal A breast cancer.Because of tumor progression despite having undergone bilateral ovarectomy and systemic therapy,the patient was treated with PBT BE total dose of 64.40 Gy to each gross tumor and 56.00 Gy to the upper mediastinal and retrosternal lymphatics including the entire sternum in 28 fractions.Follow-up computed tomography showed a partial remission,without evidence of newly emerging metastasis.At 19 mo after the PBT,the patient developed a radiation-induced pericardial disease and pleural effusions with clinical burden of dyspnea,which were successfully treated by drainage and corticosteroid.Cytological analysis of the puncture fluid showed no malignancy,and the subsequent computed tomography scan indicated stable disease as well as significantly decreased pericardial and pleural effusions.The patient remains free of progression to date.CONCLUSION PBT was a safe and effective method of reirradiation for locoregionally recurrent breast cancer in our patient.

Neutron Capture Therapy (NCT) & In-Hospital Neutron Irradiator (IHNI)——a new technology on binary targeting radiation therapy of cancer

BNCT is finally becoming ＂a new option against cancer＂. The difficulties for its development progress of that firstly is to improve the performance of boron compounds, secondly, it is the requirements of quantification and accuracy upon radiation dosimetry evaluation in clinical trials. Furthermore, that is long anticipation on hospital base neutron sources. It includes dedicated new NCT reactor, accelerator based neutron sources, and isotope source facilities. In ad- dition to reactors, so far, the technology of other types of sources for clinical trials is not yet completely proven. The In- Hospital Neutron lrradiator specially designed for NCT, based on the MNSR successfully developed by China, can be installed inside or near the hospital and operated directly by doctors. The Irradiator has two neutron beams for respective treatment of the shallow and deep tumors. It is expected to initiate operation in the end of this year. It would provide a safe, low cost, and effective treatment tool for the NCT routine application in near future.

Leakage-Penumbra effect in intensity modulated radiation therapy step-and-shoot dose delivery

AIM: To study the leakage-penumbra(LP) effect with a proposed correction method for the step-and-shoot intensity modulated radiation therapy(IMRT).METHODS: Leakage-penumbra dose profiles from 10 randomly selected prostate IMRT plans were studied. The IMRT plans were delivered by a Varian 21 EX linear accelerator equipped with a 120-leaf multileaf collimator(MLC). For each treatment plan created by the Pinnacle3 treatment planning system,a 3-dimensional LP dose distribution generated by 5 coplanar photon beams,starting from 0o with equal separation of 72 o,was investigated. For each photon beam used in the stepand-shoot IMRT plans,the first beam segment was set to have the largest area in the MLC leaf-sequencing,and was equal to the planning target volume(PTV). The overshoot effect(OSE) and the segment positional errors were measured using a solid water phantom with Kodak(TL and X-OMAT V) radiographic films. Film dosimetric analysis and calibration were carried out using a film scanner(Vidar VXR-16). The LP dose profiles were determined by eliminating the OSE and segment positional errors with specific individual irradiations. RESULTS: A non-uniformly distributed leaf LP dose ranging from 3% to 5% of the beam dose was measured in clinical IMRT beams. An overdose at the gap between neighboring segments,represented as dose peaks of up to 10% of the total BP,was measured. The LP effect increased the dose to the PTV and surrounding critical tissues. In addition,the effectdepends on the number of beams and segments for each beam. Segment positional error was less than the maximum tolerance of 1 mm under a dose rate of 600 monitor units per minute in the treatment plans. The OSE varying with the dose rate was observed in all photon beams,and the effect increased from 1 to 1.3 Gy per treatment of the rectal intersection. As the dosimetric impacts from the LP effect and OSE may increase the rectal post-radiation effects,a correction of LP was proposed and demonstrated for the central beam profile for one of the planned beams. CONCLUSION: We concluded that the measured dosimetric impact of the LP dose inaccuracy from photon beam segment in step-and-shoot IMRT can be corrected.

Improving patient care and accuracy of given doses in radiation therapy using in vivo dosimetry verification

Objective This work aims to verify and improve the dose given for cancer patients in radiation therapy by using diodes to enhance patient in vivo dosimetry on a routine basis. Some characteristics of two available semi-conductor diode dosimetry systems were evaluated. Methods The diodes had been calibrated to read the dose at Dmax below the surface. Correction factors of clinical relevance were quantified to convert the diode readings into patient dose. The diode was irradiated at various gantry angles （increments of 45~）, various Field Sizes and various Source to Surface Distances （SSDs）. Results The maximal response variation in the angular response with respect to an arbitrary angle of 0~ was 1.9%, and the minimum variation was 0.5%. The response of the diode with respect to various field siz- es showed the minimum and the maximum variations in the measured dose from the diode; the calculated doses were -1.6% （for 5 cm x 5 cm field size） and 6.6% （for 40 cm x 40 cm field size）. The diode exhibited a significant perturbation in the response, which decreased with increasing SSD. No discrepancies larger than 5% were detected between the expected dose and the measured dose. Conclusion The results indicate that the diodes exhibit excellent linearity, dose reproducibility and minimal anisotropy; that they can be used with confidence for patient dose verification. Furthermore, diodes render real time verification of the dose delivered to patients.

Application of Statistical Process Control for Setting Action Thresholds as Quality Assurance of Dose Verifications in External Beam Radiotherapy

Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and Methods: A study of QA verification of target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different cancer treatment centers in Kenya was conducted. The target doses were determined from measured entrance doses by the diode in vivo dosimetry. Process Behavior Charts (PBC) developed by SPC were applied for setting Action Thresholds (AT) on the target doses. The AT set was then proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion: Target doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the Process Behavior Charts could be applied as QA for verified doses in EBRT. Results for the two sub-groups of n = 3 and n = 4 that were tested produced action thresholds which are within clinical dose specifications for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. So the concept of SPC could be applied in setting QA action limits for dose verifications in EBRT.

Proton therapy for hepatocellular carcinoma:Current knowledges and future perspectives

Hepatocellular carcinoma(HCC) is the second leading cause of cancer-related death, as few patients can be treated with currently available curative local modalities. In patients with HCC where curative modalities are not feasible, radiation therapy(RT) has emerged as an alternative or combination therapy. With the development of various technologies, RT has been increasingly used for the management of HCC. Among these advances, proton beam therapy(PBT) has several unique physical properties that give it a finite range in a distal direction, and thus no exit dose along the beam path. Therefore, PBT has dosimetric advantages compared with X-ray therapy for the treatment of HCC. Indeed, various reports in the literature have described the favorable clinical outcomes and improved safety of PBT for HCC patients compared with X-ray therapy. However, there are some technical issues regarding the use of PBT in HCC, including uncertainty of organ motion and inaccuracy during calculation of tissue density and beam range, all of which may reduce the robustness of a PBT treatment plan. In this review, we discuss the physical properties, current clinical data, technical issues, and future perspectives on PBT for the treatment of HCC.

Efficacy and safety of intraoperative radiotherapy in rectal cancer:A systematic review and meta-analysis

BACKGROUND In recent years,intraoperative radiotherapy(IORT)has been increasingly used for the treatment of rectal cancer.However,the efficacy and safety of IORT for the treatment of rectal cancer are still controversial.AIM To evaluate the value of IORT for patients with rectal cancer.METHODS We searched PubMed,Embase,Cochrane Library,Web of Science databases,and conference abstracts and included randomized controlled trials and observational studies on IORT vs non-IORT for rectal cancer.Dichotomous variables were evaluated by odds ratio(OR)and 95%confidence interval(CI),hazard ratio(HR)and 95%CI was used as a summary statistic of survival outcomes.Statistical analyses were performed using Stata V.15.0 and Review Manager 5.3 software.RESULTS In this study,3 randomized controlled studies and 12 observational studies were included with a total of 1460 patients,who are mainly residents of Europe,the United States,and Asia.Our results did not show significant differences in 5-year overall survival(HR=0.80,95%CI=0.60-1.06;P=0.126);5-year disease-free survival(HR=0.94,95%CI=0.73-1.22;P=0.650);abscess(OR=1.10,95%CI=0.67-1.80;P=0.713),fistulae(OR=0.79,95%CI=0.33-1.89;P=0.600);wound complication(OR=1.21,95%CI=0.62-2.36;P=0.575);anastomotic leakage(OR=1.09,95%CI=0.59-2.02;P=0.775);and neurogenic bladder dysfunction(OR=0.69,95%CI=0.31-1.55;P=0.369).However,the meta-analysis of 5-year local control was significantly different(OR=3.07,95%CI=1.66-5.66;P=0.000).CONCLUSION The advantage of IORT is mainly reflected in 5-year local control,but it is not statistically significant for 5-year overall survival,5-year disease-free survival,and complications.

Radiotherapy for Carcinoma of the Esophagus: Progress of Treatment and Research in China

Carcinoma of the esophagus is a common malignancy in China. Radiotherapy is one of the most important modalities of treatment. This article provides a review of the natural history of this disease, the results of radiotherapy for esophageal cancer and the recent advances in radiation techniques in China. Significant progress has been made in this area of research and treatment. Combined treatment modalities and new therapies are being evaluated and may be expected to contribute to improved patient outcomes and better palliation of symptoms in the future.

皮肤病变的浅层放射治疗技术进展

放射疗法作为治疗皮肤病变的重要手段,已有百年的发展历程。得益于多种新颖的放射治疗(以下简称放疗)技术、方法和设备的出现,放射疗法在瘢痕疙瘩和皮肤癌等良性病变和恶性皮肤肿瘤的长期临床应用中得到了不断的应用、推广和完善。当前,电子线放疗、后装放疗、放射性β核素敷贴放疗和浅层X射线放疗等方法已广泛应用于皮肤病变治疗领域。本文旨在系统性地介绍上述浅层放疗技术,分析其优劣及应用范围,梳理浅层放疗领域的新兴需求与挑战,展望其未来的发展趋势。

摆位误差对左乳癌术后放射治疗剂量分布的影响

目的 使用千伏级锥形束计算机断层扫描(kV-CBCT)技术测量左乳癌术后放射治疗摆位误差,探讨摆位误差对剂量分布的影响。方法 选取2021年9月至2022年12月在宣城市人民医院接受放射治疗的左乳癌术后患者30例为研究对象,提取每位患者前3次放射治疗前的kV-CBCT图像,分别与计划CT图像配准,由配准系统计算获得患者左右(X)、头脚(Y)、胸背(Z)方向摆位误差。以第1次配准结果作为校正前的误差,以第2、3次配准结果作为校正后的误差,在治疗计划系统中按校正前、后误差大小平移计划中心点,计算校正前的计划(S-Plan)和校正后的计划(C-Plan)的剂量,并与治疗计划(T-Plan)进行比较,分析3者在计划靶区(PTV)、浅表区域、危及器官方面的剂量差异,以及计划的伽马通过率差异。结果 校正前摆位误差分别为(1.85±3.76) mm、(-1.80±3.25) mm、(-2.10±3.99) mm,校正后摆位误差平均值分别为(0.04±1.59) mm、(0.10±1.55) mm、(-0.01±1.47) mm。3组计划的PTV D_(98)、D_(95)、D_(mean)、均匀性指数(HI)、适形性指数(CI)和浅表区域D_(mean)间差异均具有统计学意义(P<0.05),两两比较显示,S-Plan和T-Plan、C-Plan间差异均具有统计学意义(P<0.05),3组计划患侧肺的V_(5)、V_(20)、V_(30)、D_(mean)、心脏的D_(mean)、V_(5)和脊髓D_(max)间差异均具有统计学意义(P<0.05),两两比较显示,S-Plan和T-Plan、C-Plan间差异均具有统计学意义(P<0.05),3组计划的伽马通过率间差异具有统计学意义(P<0.05),两两比较显示,S-Plan和T-Plan、C-Plan间差异均具有统计学意义(P<0.05)。结论 使用kV-CBCT测量并校正左乳癌术后放射治疗患者摆位,能有效减少摆位误差及其对剂量分布的影响,具有良好的可靠性和可重复性。

基于SEER数据库分析直肠癌外放疗后第二原发膀胱癌的发生风险与预后

目的分析直肠癌(RC)患者围手术期外放疗(EBRT)对第二原发膀胱癌(SPBC)发病风险及预后的影响。方法通过监测、流行病学和最终结果(SEER)数据库回顾性筛选1973年1月1日至2015年12月31日期间病理确诊RC患者51649例。利用SEER*Stat软件,采用泊松回归计算标准化发病率(SIR)。使用R软件,采用Fine-Gray竞争风险回归分析评估RC患者发生SPBC的累积发生率。最后使用倾向评分匹配Kaplan-Meier法评估SPBC患者的生存结局。结果在51649例RC患者中,15612例患者同时了接受手术和EBRT,而36037例患者仅接受手术治疗。总计随访30年,放疗组(RT组)SPBC的累计发病率为4.50%,无放疗组(NRT组)为2.20%。RT组的SIR高于普通人群(SIR=1.43,95%CI:1.24~1.64,P<0.050)。竞争风险回归分析显示,接受放疗与更高的SPBC发生风险相关(HR=1.49,95%CI:1.13~1.95,P=0.004)。RT组和NRT组经倾向评分匹配后合并的SPBC患者的生存分析结果显示,两组患者10年总生存期的差异有统计学意义(62.8%vs 72.7%,P=0.010)。此外,RT组(27.7%vs 40.4%,P=0.005)和NRT组(24.2%vs 35.1%,P<0.001)合并SPBC患者的10年总生存期均显著低于仅诊断原发膀胱癌患者。结论放疗是RC长期生存患者发生SPBC的重要危险因素,且可能与合并SPBC患者的不良预后有关。

Accelerated partial breast irradiation:Current evidence and future developments

Whole breast irradiation after breast-conserving surgery for early breast cancer has become one of the standard treatment modes for breast cancer and yields the same effect as radical surgery.Accelerated partial breast irradiation(APBI)as a substitute for whole breast irradiation for patients with early breast cancer is a hot spot in clinical research.APBI is characterised by simple high-dose local irradiation of the tumour bed in a short time,thus improving convenience for patients and saving costs.The implementation methods of APBI mainly include brachytherapy,external beam radiation therapy,and intraoperative radiotherapy.This review provides an overview of the clinical effects and adverse reactions of the main technologies of APBI and discusses the prospects for the future development of APBI.

锥形束CT图像引导在胸部肿瘤患者放疗摆位中的实施效果

目的分析在胸部肿瘤患者放疗摆位中应用锥形束CT图像引导的效果。方法选择2020年1月—2023年7月曹县人民医院收治的40例胸部肿瘤患者为研究对象,所有患者均接受常规电子射野影像仪图像检查与锥形束CT图像检查,分别作为对照组与研究组,比较两组不同方向摆位偏差、时间相关指标。结果研究组患者的不同方向摆位偏差均低于对照组低,差异有统计学意义(P均<0.05)。研究组的摆位时间为(150.52±14.29)s,长于对照组的(49.53±15.29)s,差异有统计学意义(t=30.519,P<0.05)。两组图像获取时间比较,差异无统计学意义(P>0.05)。结论在胸部肿瘤患者放疗摆位中实施锥形束CT图像检查可减少方向摆位偏差。

Clinical evaluation of 4D dynamic dose for thoracic tumor stereotactic body radiation therapy with variable parameters

Objective:To evaluate the dose uncertainty in stereotactic body radiation therapy induced by respiratory motion using a 4D dynamic dose(4DDD)reconstruction method.Methods:A retrospective analysis was conducted on five lung cancer patients who received static intensitymodulated radiation therapy.The 4DDD was constructed using beam delivery log files,four-dimensional computed tomography(4DCT)scans,and treatment plans.To evaluate the impact of respiratory motion,4DDD calculations were performed with 10 starting phases for each field.A total of 270 field doses were simulated and calculated.The differences between the cumulative volume histogram in whole-course treatment and the field doses'gamma passing rate(GPR)were compared.The correlations between plan complexity metrics and the dose deviation caused by respiratory motion were evaluated independently.The phase distributions of 398 subfields were calculated and evaluated for the influence of dose rate and breathing frequency.Results:The GPRs of all fields were different among various starting phases,with the highest range from 62.20% to 76.87% for 2 mm/3%GPR.The deviation of mean point dose was(5.42±5.21)%,and the deviation in the mean dose and D98% within the internal gross tumor volume were(0.97±0.71)% and(0.77±0.53)%,respectively.There was a significant correlation between the beam aperture-to-volume(BA2V)ratio and the average 2 mm/2%GPR(R?0.601,P<0.01).Lower dose rates led to a more homogeneous distribution of phases among subfields(t?44.100,P<0.001).Conclusions:Different beam starting phases had a limited impact on the overall treatment evaluation.However,the respiratory motion could be observed to induce dose deviations using the 4DDD reconstruction model,particularly for fields with small BA2V.

鼻咽癌逆向调强计划中照射野方向和照射野数目对剂量分布的影响

背景与目的:调强放疗技术正逐步应用于鼻咽癌的治疗。对于鼻咽癌这种对放疗技术要求最为复杂的头颈部肿瘤,制定IMRT计划是一个费时费力的过程,有许多物理参数会影响到剂量分布,其中照射野方向和数目的选择又是一个需要反复实验的过程。本研究以鼻咽癌为例着重探讨射野方向和数目对IMRT计划剂量分布的影响,为制定鼻咽癌IMRT计划提供一些参考,可以减少优化中反复实验所需要的时间。方法:选择临床常见的早期鼻咽癌10例、局部晚期鼻咽癌10例,对每个病例分别制定9野、7野调强放疗计划,7野计划有A、B两种不同的线束入射角度方案,同一病例的7野、9野计划均应用相同的物理目标函数。将7野A组和B组做比较以优化射野方向,较优的一组再与9野计划做比较以优化照射野数目;用靶区覆盖度,靶区均匀性、靶区适形度、机器跳数,子野数目等物理参数作为计划评价指标。结果:对于早期病例,7野A组、B组和9野计划均能满足要求,两种计划的靶区覆盖度、靶区均匀性及靶区适形度的差别不大,7野A组中机器跳数、子野数均低于B组;对于晚期病例,虽然9野计划中机器跳数尤其是子野数都劣于7野A组及B组计划,但9野计划在靶区覆盖度明显优于7野计划。结论:照射野方向和照射野的数目对剂量分布有影响,增加照射野的数目可以改善体积较大的病灶的剂量分布。对病灶体积大的肿瘤,9野计划比7野的优势明显。综合考虑物理及生物效应,建议对于早期病例7野计划可基本解决问题,对局部晚期病例,9野方案较为可靠。

颈胸上段食管癌两种固定方式放疗摆位误差的对比研究

目的利用锥形束CT(CBCT)研究颈、胸上段食管癌使用颈肩膜、体膜两种固定方式放疗时的摆位误差,为临床治疗更优选择提供依据。方法随机选取66例拟行放射治疗的颈、胸上段食管癌患者,平均分成A、B两组。A组定位时采用热塑颈肩膜固定,B组采用热塑体膜固定。利用CBCT对每位患者首次治疗前摆位误差进行测量,然后使用SPSS17.0软件统计分析。结果 A组在左右(X)、头脚(Y)、前后(Z)方向上测量的摆位误差分别为(0.20±0.14)、(0.15±0.15)、(0.23±0.15)cm,而B组为(0.16±0.13)、(0.24±0.16)、(0.18±0.12)cm,A组误差数据优于B组,特别在头脚(Y)轴差异有统计学意义(P<0.05)。结论颈肩膜固定技术可以减少颈、胸上端食管癌患者放疗中的摆位误差,操作简便易行,值得临床进一步推广应用。

锥形束CT在宫颈癌调强放射治疗中摆位误差分析

目的探讨每日锥形束CT(CBCT)技术在纠正宫颈癌放疗人工摆位误差中的应用价值。方法选取接受调强放射治疗(IMRT)的宫颈癌患者18例,每日放疗前均行CBCT扫描,并与计划CT图像骨性匹配,结合手动微调,获得前后(Vrt)、头脚(Lng)、左右(Lat)三个方向的线性摆位误差,摆位误差纠正后再次CBCT扫描,分别记录每次的摆位误差并进行分析。结果 18例患者共行906次CBCT扫描,摆位误差纠正前和纠正后Vrt方向总平均值(M)、系统误差(∑)、随机误差(σ)分别为0.581、4.068、1.160mm和0.049、0.292、0.277mm,Lng方向纠正前后分别为0.789、3.637、2.031mm和0.477、0.391、0.539mm,Lat方向纠正前后分别为-0.375、2.515、1.564mm和0.094、0.109、0.238mm。摆位误差纠正前Vrt、Lng、Lat方向CTV-PTV外放边界(MPTV)分别为10.981、10.514、7.381mm,摆位误差纠正后MPTV分别为0.925、1.353、0.440mm。摆位误差纠正前和纠正后肿瘤中心点移动距离分别为(8.890±7.222)mm和(1.021±1.075)mm,CBCT纠正后摆位误差范围较纠正前显著减少(P<0.05)。结论宫颈癌IMRT中每日行CBCT校正可明显减少摆位误差,提高放疗精确性。

CBCT在非小细胞肺癌精确放疗中的应用

目的探讨锥形束CT(CBCT)在非小细胞肺癌(NSCLC)精确放疗中的应用价值。方法应用安装在直线加速器上的CBCT对患者实施治疗前的扫描,根据CBCT图像,测量其运动范围,确定个体化的肉眼肿瘤区(GTV)至计划靶区(PTV)的外放边界。结果通过使用CBCT,考虑肿瘤运动幅度,会造成GTV平均增加30.4 cm3,平均百分数为115.8%;而PTV平均减少40.2 cm3,平均百分数为39.4%。结论利用CBCT图像,可以减小GTV外放边界,减少正常肺组织受照剂量,降低放射性肺损伤指标V20、Dm ea和脊髓最大受量,从而降低正常肺组织和脊髓的放射性损伤发生率。