Comparative Dosimetric Study for Treating Left Sided Breast Cancer Using Three Different Radiotherapy Techniques:Tangential Wedged Fields, Forward Planned Segmented Filed, and IP-IMRT

Background: Radiation therapy should not only be directed to improve the local control, which has a survival benefit, but also should be directed to minimize the risk of complications, which may develop in critical organs. Several studies have reported that field-in-field (FiF) radiotherapy technique improves the dose homogeneity, decreases doses to lungs, heart and contralateral breast compared with conventional wedged technique. Purpose: compare the dosimetry for the left breast cancer radiotherapy using three different radiotherapy techniques, tangential wedged fields (TW), segmented field (FiF) and inverse planning IMRT (IP-IMRT). Material and Methods: Twenty patients have undergone left breast-conservative surgery and received a prescribed dose of 50 Gy/25 fractions. Results: The mean PTV receiving >105% (V105) dose was1.75% for IP-IMRT, 2.03% for FiF, and 4.82% for TW. The mean V95% was 92.1% for TW, 96% for FiF, and 95.1% for IP-IMRT;these differences regarding V105% and V95% are statistically significant through paired comparison between FiF vs TW and IP-IMRT vs TW, with no statistically significant difference between FiF and IP-IMRT. Better conformity and homogeneity indices for FiF and IMRT compared to TW with statistical significant difference. Regarding organs at risk, left lung and heart have higher values of V5, V10, and V20 for IP-IMRT compared to TW and FiF;the differences are statistically significant, lower coronary artery regionV30 vules for IPIMRT compared to TW and FiF but no difference in the Dmean between IPIMRT and FIF. FiF and TW decrease the contralateral breast dose significantly compared to IP IMRT. Conclusion: FiF technique is an efficient and reliable method for achieving a uniform dose throughout the whole breast resulting in improved coverage, sparing of organs at risk and reduction of acute and late toxicities.

Involved Nodal Radiotherapy vs. Involved Field Radiotherapy after Chemotherapy in the Treatment of Early Stage Hodgkin’s Lymphoma

Aim of work: This study is a prospective randomized trial aiming to investigate whether radiotherapy volume can be reduced without loss of efficacy from involved field radiotherapy (IFRT) to involved node radiotherapy (INRT) after four cycles of ABVD chemotherapy in the treatment of early stage Hodgkin’s lymphoma. Patients and Methods: Between September 2009 and January 2012, all patients with newly diagnosed early-stage favorable and unfavorable Hodgkin’s lymphoma attending to the Clinical Oncology department of Cairo University, faculty of medicine were enrolled into this study after a written consent was obtained from those cases enrolled. Patients were assigned to receive (ABVD) for four cycles followed by randomization for radiotherapy into two arms one arm of 30 Gy INRT +/– 6 Gy to residual disease or another arm of 30 Gy IFRT +/– 6 Gy to residual disease. Results: 35 patients were enrolled in this study: 16 patients in the INRT arm and 19 patients in the IFRT arm. The median observation time was 25 months. The overall survival for all eligible patients was 97% and freedom from treatment failure was 85.7%. Survival rates at the end of the study revealed no differences between INRT and IFRT arms. Also, in terms of complete remission post radiotherapy (14 versus 15), relapse (1 versus 4), and death (0 versus 1) respectively the outcome was similar in both arms. As regard acute and sub-acute toxicities no significant difference could be detected between both arms except that IFRT arm was associated with a higher incidence of radiation pneumonitis (4 versus 1 patient). Conclusion: Radiotherapy volume size reduction from IFRT to INRT after ABVD chemotherapy for four cycles produces similar results and less toxicity in patients with early-stage Hodgkin’s lymphoma especially in patients with mediastinal disease.

Evaluation of the optimal field arrangement for conformal radiotherapy for prostate cancer patients

Objective:The aim of this study was to evaluate the optimal field arrangement for conformal radiotherapy (CFRT) for prostate cancer patients.Methods:Thirty patients with prostate cancer of different grades and stages were treated with 3D conformal radiotherapy to minimize the dose to bladder,rectum and head of both femora using four fields (4F),five fields (5F),six fields (6F) and ARC techniques to minimize the risk of over dose to bladder,rectum and femoral heads.Patients received a total dose between 76 to 78 Gy given in 38 to 39 fractions over 7.5 to 8 weeks.Results:It was observed that V95,D95,D50 and D5 values for planning target volume (PTV) were comparatively higher when planned by 5 fields technique than when planned by fixed field technique (91%,91%,90% and 91.4% for skip-scan technique versus 85%,87%,86% and 88% by fixed field).The organs like rectum and urinary bladder get much higher dose when treated by fixed field techniques than rotation or 5 fields technique,when comparison was made for V95,V50 and DM values for rectum and urinary bladder obtained by 5 fields technique planning and 4/6 field planning,the value for 5 fields technique was found to be lower than 4/6 field technique (1%,70% and 51% versus 13%,91% and 55% for rectum and 4%,25% and 51% versus 16%,38% and 56% for urinary bladder respectively).Conclusion:Similarly for femoral heads,planning by full rotational technique had been observed to be beneficial as compared to when planning was done by fixed field technique (0%,0% and 29% versus 0%,1% and 28%).

Technical and Dosimetric Study of Four Facio-cervical Fields Conformal Radiotherapy for Nasopharyngeal Carcinoma

Objective： The aim of this study is to establish the methods of four facio-cervical fields＇ conformal radiotherapy （4F-CRT） for nasopharyngeal carcinoma （NPC）, and to optimize the methods for clinical practice. Methods and Materials： 40 patients with untreated NPC of T1-T4 （1997AJCC Staging System） were rolled into this study. Conventional and four ratio-cervical fields conform plans were designed for each patient using Pinnacle 8.0 three-dimension treatment planning system （3D-TPS）： 1） Improved plan, four ratio-cervical fields＇conform plans, anterior, posterior ratio-cervical and 2 lateral opposing facio-eervical fields; 2） Conventional plan, two lateral opposing facio-cervical fields only with the same dose delivered to the target in each plan, close volume histograms （DVHs） of the targets and normal organs, brain stem, spinal cord, parotid glands, and temporal mandibular joints （TMJs） were compared and the dose distribution were evaluated. Results： 1） The dose distribution of the improved plan could meet the requirements for the target volume. 2） There was not any significant difference in the dose of spinal cord between the two plans. The mean doses of Dmax for brain stem in conventional plan were much lower than those in the improved plan, though both were within safety limits. 3） Compared with the conventional plans, the improved plan significantly decreased the hotspot areas in the target volume and had better parotid glands and temporal mandibular joints sparing effect. Conclusion： Compared with the conventional plan, the improved plan provides satisfactory dose coverage to the tumor volume and better sparing of the parotid gland, TMJs and other normal tissues in external beam radiotherapy of NPC.

Validation of the TOPAS Monte-Carlo Code of the Off-Field Dose of a 6 MV Synergy Linac

The risk of radiation-induced second cancer and the late tissue loss due to Off-field doses in radiotherapy remain a serious concern. Monte Carlo (MC) simulation is currently one of the most accurate methods for calculating these doses. MC simulation model based on the Particle Simulation Tool (TOPAS) has been developed to simulate the off-field dose of an Elekta Synergy linear accelerator (Linac) emitting 6 MV photons. Measurements were taken in a water phantom using an ionization chamber to validate this model. The Percentage Depth Dose (PDD) at the depth of 0.0, 5.0, 10.0 and 15.0 cm from the beam axis for a 10 × 10 cm2 field size was measured and simulated. Off-field dose profiles at the depth of 1.5 (dmax), 5.0 and 10.0 cm for field sizes of 5 × 5, 10 × 10, 15 × 15, and 20 × 20 cm2 respectively were measured and simulated. Comparison of measured and simulated off-field dose values showed a good agreement. The average gamma passing rate of the PDDs and profiles curves for off-field doses were 87.5% and 98.11% respectively. The local dose difference based on the PDD curve between the measured and simulated was less than 6.0 % for all locations. For all field size considered in this study, the average difference between profile curves for off-field dose measured and simulated was 9.1%. PDDs and Profiles curves for off-field dose simulation uncertainties were less than 2.0% and 1.0% respectively. TOPAS-MC simulation model developed is a good representation of our 6 MV Linac Elekta Synergy for assessing off-field dose, which would be the primary cause of some secondary cancers.

Measurement and analysis on distribution of radiation field dose inside thetreatment room of TaiChi Pro multimodal integrated digitalradiotherapy system

Objective:To examine the leakage radiation dose from the accelerator module's primary beam self-shielding,aswell as stray radiation levels and distribution in the treatment room across various planes for the innovative X/γmultimodal radiotherapy system,TaiChi Pro,which is the world's first digitally integrated system that combines alinear accelerator,multi-source rotational focused gamma knife,and multi-modal image guidance,in order toformulate treatment room safety strategies and estimate additional radiation doses to patients.Methods:The TaiChi Pro multi-mode integrated radiotherapy system was utilized with a 6 MV X-ray accelerator inthe flatten-filter free(FFF)treatment mode.The system has a primary radiation beam self-shielding,and anisocenter dose rate of 800 cGy/min.For detection points in various planes,an x,y,z coordinate system wasestablished with the isocenter as the origin.To simulate the situation of patient,water-equivalent phantom wasemployed.The ambient dose equivalent and ambient dose equivalent rate at detection points in the radiation fieldwere measured using thermoluminescence dosimeters.Results:The self-shielding area achieved a maximum dose of 114.0 mGy at 1 m distance from the target point after3 min of cumulative irradiation.The leakage radiation ratios at all points remained below 0.5%,fulfilling the selfshielding design requirements.Regarding the couch,the highest radiation was observed in the opposite directionof the beam at the target point.The stray radiation on the treatment bed plane resulted in an ambient doseequivalent that did not exceed 0.5%of the ambient dose equivalent at the central point.Conclusion:The levels and distribution patterns of stray and leakage radiation inside the TaiChi Pro treatmentroom meet the requirements of the relevant national standard.The measured values of indoor radiation levels anddistribution are very useful for room shielding design and personnel protection.

Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET

AIM:To study the peripheral dose(PD) from highenergy photon beams in radiotherapy using the metal oxide semiconductor field effect transistor(MOSFET) dose verification system.METHODS:The radiation dose absorbed by the MOSFET detector was calculated taking into account the manufacturer's Correction Factor,the Calibration Factor and the threshold voltage shift.PD measurements were carried out for three different field sizes(5 cm×5 cm,10 cm×10 cm and 15 cm×15 cm) and for various depths with the source to surface distance set at 100 cm.Dose measurements were realized on the central axis and then at distances(1 to 18 cm) parallel to the edge of the field,and were expressed as the percentage PD(% PD) with respect to the maximum dose(dmax).The accuracy of the results was evaluated with respect to a calibrated 0.3 cm3 ionization chamber.The reproducibility was expressed in terms of standard deviation(s) and coefficient of variation.RESULTS:% PD is higher near the phantom surface and drops to a minimum at the depth of dmax,and then tends to become constant with depth.Internal scatter radiation is the predominant source of PD and the depth dependence is determined by the attenuation of the primary photons.Closer to the field edge,where internal scatter from the phantom dominates,the % PD increases with depth because the ratio of the scatter to primary increases with depth.A few centimeters away from the field,where collimator scatter and leakage dominate,the % PD decreases with depth,due to attenuation by the water.The % PD decreases almost exponentially with the increase of distance from the field edge.The decrease of the % PD is more than 60% and can reach up to 90% as the measurement point departs from the edge of the field.For a given distance,the % PD is significantly higher for larger field sizes,due to the increase of the scattering volume.Finally,the measured PD obtained with MOSFET is higher than that obtained with an ionization chamber with percentage differences being from 0.6% to 34.0%.However,when normalized to the central dmax this difference is less than 1%.The MOSFET system,in the early stage of its life,has a dose measurement reproducibility of within 1.8%,2.7%,8.9% and 13.6% for 22.8,11.3,3.5 and 1.3 cGy dose assessments,respectively.In the late stage of MOSFET life the corresponding values change to 1.5%,4.8%,11.1% and 29.9% for 21.8,2.9,1.6 and 1.0 cGy,respectively.CONCLUSION: Comparative results acquired with the MOSFET and with an ionization chamber show fair agreement, supporting the suitability of this measurement for clinical in vivo dosimetry.

Analyzing Planning Techniques for Whole Brain Radiotherapy

Aims: This study compares data between the Field in Field planning and Wedge planning techniques to figure out which technique has better dose coverage and distribution for PTV, and, if using FiF technique for whole brain treatment, how many beams will have better plan. Methods: 56 patients, who need to radiate whole brain with 30 Gy/10 fractions, have been selected for this study. Four plans have been made for each patient (FiF1—one subfield per field plan, FiF2—two subfields per field plan, FiF3—three subfields per field plan, and a Wedge plan). Results: The results of Field in Field plans including Compare dose distribution on the transverse CT slice, plan evaluation using DVH, number MU of plan, Dmax, HI, HTCI, DmaxPTV, DmeanPTV. Volume of PTV with the dose over 105% prescribed dose, dose of organ at risk, and Quality Assurance (QA) plan, are better than those of Wedge plan. Conclusions: Plans using Field in Field technique has better coverage, is more homogeneous in dose distribution than plan using Wedge technique. When using Field in Field technique for whole brain radiotherapy, using three subfields per field has better result than two subfields per field and one subfield per field.

Planning issues on linac-based stereotactic radiotherapy

This work aims to summarize and evaluate the current planning progress based on the linear accelerator in stereotactic radiotherapy(SRT).The specific techniques include 3-dimensional conformal radiotherapy,dynamic conformal arc therapy,intensity-modulated radiotherapy,and volumetric-modulated arc therapy(VMAT).They are all designed to deliver higher doses to the target volume while reducing damage to normal tissues;among them,VMAT shows better prospects for application.This paper reviews and summarizes several issues on the planning of SRT to provide a reference for clinical application.

Technical and Dosimetric Study of Four Facio-cervical Fields Conformal Radiotherapy for Nasopharyngeal Carcinoma

Objective: The aim of this study is to establish the methods of four facio-cervical field's conformal radiotherapy(4F-CRT) for nasopharyngeal carcinoma(NPC), and to optimize the methods for clinical practice. Materials and Methods:40 patients with untreated NPC of T1-T4(1997 AJCC Staging System) were rolled into this study.Conventional and four facio-cervical fields conform plans were designed for each patient using Pinnacle 8.0 three-dimension treatment planning system(3D-TPS)as follows: 1. Improved plan, four facio-cervical field's conform plan, anterior, posterior facio-cervical and two lateral opposing facio-cervical fields; 2. Conventional plan, two lateral opposing facio-cervical fields delivered to the target in each plan, only with the same dose dose volume histograms(DVHs) of the targets and normal organs, brain stem,spinal cord, parotid glands, and temporal mandibular joints(TMJs) were compared and the dose distribution were evaluated. Results: 1.The dose distribution of the improved plan could meet the requirements for the target volume. 2. There was not any significant difference in the dose of spinal cord between the two plans.The mean doses of Dmaxfor brain stem in conventional plan were much lower than those in the improved plan,though both were within safety limits. 3. Compared with the conventional plans, the improved plan significantly decreased the hotspot areas in the target volume and had better parotid glands and temporal mandibular joints sparing effect. Conclusion:Compared with the conventional plan, the improved plan provides satisfactory dose coverage to the tumor volume and better sparing of the parotid gland, TMJs and other normal tissues in external beam radiotherapy of NPC.

胸部肿瘤三维适形调强放疗摆位误差相关因素分析

分析胸部肿瘤患者行三维适形调强放疗(IMRT)时产生摆位误差的相关因素,以准确计算出临床靶区(CTV)外放边界(摆位扩边(SM)值),从而实现安全放疗.以莆田学院附属医院接受IMRT治疗的83例胸部恶性肿瘤患者为研究对象,应用体位固定技术及电子射野影像装置(EPID)测量比较胸部恶性肿瘤IMRT的摆位误差,采用多元线性回归分析方法对摆位误差相关因素进行分析,进而分类计算出其SM值.结果显示,83例受试者在X轴、Y轴、Z轴上的SM值分别为0.31、0.28、0.28 cm;靶区定位、性别及肺容量分别为Y轴个体随机误差、Z轴个体系统误差、Z轴个体随机误差的独立影响因素.这表明肿瘤患者行IMRT治疗时靶区定位、性别及肺容量在不同方向上影响其摆位误差.

立体定向放射治疗小射野探测器研究进展

由于侧向带电粒子平衡的缺失、主光子源的遮挡,以及在小射野测量中可以选择的探测器有限,对现代放射治疗技术进行小野剂量学测定提出诸多挑战,这些挑战极大影响了剂量学的准确性。过量辐射事故表明对小野剂量学测定的适当方法了解不足。本综述介绍了目前适合在小野剂量学测量中应用的各类型探测器,包括微型电离室、半导体探测器、金刚石探测器、塑料闪烁体探测器、放射变色胶片、热释光探测器、放射光致发光玻璃探测器、光受激发光探测器、聚合物凝胶剂量计,为物理师在选择小野探测器时提供参考。

MRI/CT融合图像与CT图像勾画海马区在HP-WBRT中TOMO适宜参数的研究

目的探索MRI/CT融合图像与CT图像在勾画海马区时,螺旋断层放射治疗技术(Tomotherapy,TOMO)应用于海马保护性全脑放射治疗的适宜参数。方法选取2017年1月至2022年12月间在陕西省肿瘤医院实施海马保护性全脑放射治疗的66例患者数据为研究对象,其中36例患者海马区使用MRI/CT融合图像进行勾画,30例患者使用CT图像进行勾画。通过调整不同的调制因子(Modulation Factor,MF)、射野宽度(Field Width,FW)和螺距(Pitch)参数,采用不同的参数组合,评估治疗计划的靶区覆盖率和危及器官剂量,以探索适用于TOMO的合适参数。结果基于MRI/CT融合图像勾画的海马区体积(HPL、HPR两侧)显著大于基于CT图像勾画的海马区体积(P<0.001)。使用MRI/CT融合图像勾画海马区时,TOMO的最佳MF取值为2.7,使用CT图像勾画时最佳取值则为2.5;两者的FW最佳值均为2.5 cm;MRI/CT融合图像的Pitch最佳值为0.287,CT的Pitch取值为0.287和0.430时均符合要求。结论通过比较MRI/CT融合图像和CT图像勾画海马区时的不同参数方案,得出适用于海马保护性全脑放射治疗的TOMO适宜参数,可为优化放疗方案,提高海马保护性全脑放射治疗的准确性和安全性提供参考。

容积弧形动态旋转调强与固定野调强放疗技术在乳腺癌根治术后患者中的剂量学分布特征

目的:探讨乳腺癌根治术后患者开展容积弧形动态旋转调强放疗(VMAT)与固定野调强放疗(IMRT)技术的剂量学分布.方法:选取本院2022年2月至2023年6月收治的60例乳腺癌患者作为研究对象.采用随机数字表法将其分为研究组(n=30,采用VMAT技术)和对照组(n=30,采取IMRT技术).对两组患者靶区剂量分布、危及器官剂量分布、体内受照剂量分布及加速器输出机器跳数与治疗时间进行统计学比较.结果:VMAT与IMRT两种技术均符合靶区处方要求,为确保比较的可操作性,将计划靶区95%剂量统一为5000cGy.与对照组比较,研究组患者V100、D98%靶区剂量分布较高,Dmean与CI值较高,D2%、Dmax、HI值较低,差异均有统计学意义(P<0.05);两组患者V106、D95%比较,差异无统计学意义(P>0.05).与对照组比较,研究组患者健侧乳腺Dlcc、Dmax、Dmean较低,健侧肺V5、Dmax较低,患侧肺V20、V30、Dmax、Dmean较低,心脏V5、V20、V30、Dmean较低,肝V5、V50、Dmax较低,脊髓Dlcc、Dmean值较低,差异均有统计学意义(P<0.05);其余指标比较,差异均无统计学意义(P>0.05).与对照组比较,研究组患者V5、V10、V20、V30参数较低,差异均有统计学意义(P<0.05),两组患者V40、V50参数比较,差异均无统计学意义(P>0.05).与对照组比较,研究组患者平均机器跳数较少,平均治疗时间缩短,差异均有统计学意义(P<0.05).结论:对乳腺癌根治术后患者采取VMAT技术,较采取IMRT,更有利于确保靶区剂量分布均匀与适形度,减少体内受照与危及器官剂量,加速器输出机器跳数更少,治疗时间更短.

预防性延伸野放疗联合同步化疗与盆腔野放疗联合同步化疗治疗局部晚期宫颈癌的近远期疗效及安全性对比

目的比较预防性延伸野放疗联合同步化疗与盆腔野放疗联合同步化疗治疗局部晚期宫颈癌的近远期疗效及安全性。方法选择90例局部晚期宫颈癌患者作为研究对象,将其随机分为观察组与对照组,每组45例。给予观察组预防性延伸野放疗联合TP方案(紫杉醇+顺铂)同步化疗,给予对照组盆腔野放疗联合TP方案同步化疗。在同步放化疗结束后4周,评价两组的近期疗效及毒副反应发生情况。比较两组治疗前后血清学肿瘤标志物[鳞状细胞癌相关抗原(SCCA)、癌胚抗原、糖类抗原50(CA50)]水平。统计两组患者3年总生存率、无进展生存率及腹主动脉旁淋巴结(PALN)控制率。结果两组客观缓解率差异无统计学意义(P>0.05)。治疗后,两组患者血清SCCA、癌胚抗原和CA50水平均较治疗前降低,且观察组上述指标水平均低于对照组(均P<0.05);观察组骨髓抑制发生率高于对照组(P<0.05),但两组其他毒副反应发生率差异均无统计学意义(均P>0.05)。观察组3年无进展生存率、PALN控制率均高于对照组(均P<0.05),但两组3年总生存率差异无统计学意义(P>0.05)。结论与盆腔野放疗联合同步化疗相比,预防性延伸野放疗联合同步化疗治疗局部晚期宫颈癌患者可以更好地改善血清学肿瘤标志物水平,提高PALN控制率,远期疗效好,但增加了骨髓抑制的发生风险,两种疗法的近期疗效相当。

绝对剂量的变化对鼻咽癌调强放疗计划大野Portal Dosimetry剂量验证的影响

目的 研究加速器绝对剂量的变化对鼻咽癌调强放疗(Intensity Modulated Radiotherapy,IMRT)计划大野Portal Dosimetry(PD)剂量验证结果的影响。方法 选取12例行IMRT计划的鼻咽癌患者进行研究。每例治疗计划中,选择机架角为0°的射野(记为AA0),该射野是大野,由两个分野组成。对AA0野,制作相应的PD剂量验证计划并在一台Clinac iX加速器上执行。通过两个PD分野的矩阵相加,得到大野AA0的PD剂量分布矩阵。通过使用不同的系数与AA0射野的测量剂量分布矩阵相乘,模拟加速器绝对剂量的变化。采用3 mm/3%的Gamma分析参数,使用PD软件模块分析得到不同绝对剂量变化情况下AA0大野的Gamma通过率(G值)。使用dp表示加速器绝对剂量变化的相对百分比。对dp在-5.0%~5.0%范围内以间隔0.5%取值,分析G(dp)的变化。对G(dp)的数据使用四次多项式拟合,由拟合公式计算得到G值的最大值(G_(max))以及G≥95%对应dp值的变化范围(R95)。结果 12个AA0射野的G(0)均>95%(96.91%~99.38%)。当dp向正负方向偏离时,总体上G值呈下降趋势,但是G(0)不是G(dp)的最大值,G值随dp的变化呈拱形形状。G_(max)值的范围为97.08%~99.41%,R95值的范围为6.3%~12.0%。当-1.5%≤dp≤2.3%时,所有12个AA0野的G值均≥95%。平均G_(max)对应的dp为0.6%。结论 加速器绝对剂量的变化对鼻咽癌IMRT计划大野的PD剂量验证结果有一定影响,为了获得较好的PD剂量验证结果,应将加速器绝对剂量的变化控制在合理的范围内。本研究为评估大野的PD剂量验证结果以及测量校准加速器绝对剂量的质控工作,提供了有益的数据参考。

人体放疗辐射场检测系统研制

放疗辐射场检测系统是保证放疗安全和放疗质量的重要设备。针对检测设备测试效率低、价格昂贵等问题,基于数据采集卡和C++语言进行硬件搭建和软件编程设计,实现了放疗辐射场检测系统。经现场测试,对不同条件下检测数据进行分析,在10 cm×10 cm射野下6 MV X射线的射线质量指数为67.32%±0.68%,深度为5 cm时离轴比曲线均整度为102.78%±0.95%、对称性为101.91%±0.88%;6 MeV电子束的对称性和均整度分别为102.39%±0.36%,103.11%±0.35%。结果表明,系统具有较好的探测准确性和稳定性。

直肠癌术后调强放疗多变量组合最佳治疗模式的剂量学研究

目的探讨直肠癌术后调强放疗中治疗体位(仰卧位与俯卧位)、准直器调强方式[动态调强(SW)与静态调强(MSS)]、剂量计算算法[各向异性解析算法(AAA算法)与笔形束卷积算法(PBC算法)]、高能X射线能量(6 MV与15 MV)、放射野个数(7野与9野)以及计算网格尺寸(0.25 cm与0.50 cm)等多变量组合最佳治疗模式的剂量学特征。方法采用控制单一变量法,分别比较6种条件(共计12个变量)对靶区和危及器官的剂量学差异。基于剂量学差异结果,比较6种条件中相对更优的6个变量串联而成的A组与相对较差的6个变量串联而成的B组对靶区和危及器官的剂量学影响。剂量学评价指标包括靶区和危及器官的剂量受量、靶区剂量适形度指数(CI)和靶区均匀性指数(HI)、机器跳数(MU)、出束时间。结果对于多变量串联的统计学分析显示,采用俯卧位、AAA剂量算法、动态SW的多叶光栅(MLC)运动方式、15 MV的X线、0.25 cm计算网格尺寸且9野均分的6个变量串联的A组相较于采用仰卧位、PBC剂量算法、静态MSS的MLC运动方式、6 MV的X线、0.50 cm计算网格尺寸且7野均分的6个变量串联的B组,计划靶区(PTV)的平均剂量(D_(mean))平均降低了1.2%,CI平均增加了10.0%,HI平均降低了30.3%;小肠最大剂量(D_(max))平均降低了3.0%,膀胱4000 cm^(3)体积对应的剂量(V_(40))平均降低了31.2%,股骨头D_(max)平均降低了3.6%。结论直肠癌术后调强放疗采用俯卧位、AAA剂量算法、动态SW的MLC运动方式、15 MV的X线能量、0.25 cm计算网格尺寸和9野均分野这6个变量组成的治疗模式,是经临床剂量学证实的对直肠癌术后调强放疗的更优治疗模式。

Ⅰ-Ⅱa期宫颈癌患者术后盆腔小野放疗的临床效果

目的观察Ⅰ-Ⅱa期宫颈癌患者术后采用盆腔小野放疗的生存率及不良反应发生情况。方法选取我院2017年1月—2018年1月已接受广泛全子宫切除+盆腔区域淋巴结清扫术且具有肿瘤复发高中危因素的30例Ⅰ-Ⅱa期宫颈癌患者,进行盆腔小野放射治疗,并观察患者的生存率及不良反应发生情况。结果30例患者中,2年生存率、无疾病进展率分别为100.0%、96.7%,30例患者均具有良好的耐受性,无3级以上直肠、泌尿生殖道不良反应发生。结论对具有预后不良危险因素并已行根治性手术的Ⅰ-Ⅱa期宫颈癌患者,进行盆腔小野放疗,其结果与文献报道和我院既往同类患者放疗标准野照射进行比较,发现盆腔小野照射在保证疗效的前提下能够明显降低不良反应发生风险,提高患者的生活质量,在临床上是可行的。

106例局部晚期宫颈癌根治性同步放化疗的临床疗效及预后影响因素

目的:分析无髂总淋巴结和腹主动脉旁淋巴结转移局部晚期宫颈癌患者根治性同步放化疗临床疗效、放疗毒性反应,探讨预后影响因素。方法:回顾分析2018年1月至2020年8月川北医学院附属医院肿瘤科放疗中心行根治性同步放化疗的106例局部晚期宫颈癌患者的临床资料,其中43例采用常规全盆腔放疗(PRT),63例采用盆腔延伸野放疗(EFRT)。通过实体瘤疗效评价标准评估近期疗效,用总生存期(OS)、无进展生存期(PFS)评估远期疗效。通过单因素和多因素分析影响预后的因素。依据肿瘤放射治疗协作组放射损伤分级标准评估放疗毒性反应。结果:106例患者客观缓解率为77.4%,疾病控制率为93.4%。1、3年OS率分别为95.2%、78.5%,1、3年PFS率分别为85.1%、68.1%。多因素分析显示,PRT是局部晚期宫颈癌患者OS(HR=3.78,95%CI为1.21~11.87,P=0.023)和PFS(HR=3.13,95%CI为1.302~8.428,P=0.012)的独立危险因素;盆腔淋巴结转移数目(<3枚和≥3枚)、近期疗效是影响OS的独立预后因素(P<0.05)。年龄、近期疗效是影响PFS的独立预后因素(P<0.05)。无患者出现大于3级的急性胃肠道毒性,3例(2.8%)患者出现3~4级慢性胃肠道毒性。24例(22.6%)患者出现3~4级骨髓抑制。结论:CT、MRI或PET-CT显示无髂总和腹主动脉旁淋巴结转移局部晚期宫颈癌根治性同步放化疗近、远期疗效确切。EFRT能改善局部晚期宫颈癌患者OS和PFS。通过盆腔淋巴结转移数目(<3枚和≥3枚)、近期疗效(CR/PR/SD/PD)可预测预后。PRT、EFRT放疗毒性可接受。