复发性鼻咽癌X线调强放疗和质子治疗剂量学研究

放疗是鼻咽癌治疗的主要方法,X线调强放疗(IMXT)的临床应用和发展,是肿瘤放疗技术的一大进步,对鼻咽癌的治疗尤为重要。鼻咽癌放疗后局部复发的患者,如何提高再程放疗的局部控制率、降低危及器官的受照剂量和再程放疗的放射性损伤是众多放疗科医生所关注的问题。由于质子线以Bragg峰的形式释放能量,其良好的物理特性使得在增加靶区剂量的同时可最大限度地降低正常组织受量,从而降低并发症的发生。笔者用4例复发鼻咽癌患者进行了IMXT和质子治疗(PRT)的治疗计划比较。     

氢质子磁共振波谱联合磁共振成像对脑胶质瘤的诊断价值

目的探讨氢质子磁共振波谱(1H-MRS)联合磁共振成像(MRI)对脑胶质瘤的诊断价值。方法选取2015年10月至2016年10月间哈尔滨医科大学附属第二医院收治的48例脑胶质瘤患者,其中低级别脑胶质瘤30例,高级别脑胶质瘤18例。均在行MRI基础上行1H-MRS检查,检测N-乙酰天门冬氨酸(NAA)、肌酸(Cr)和胆碱(Cho),分析患者肿瘤实质区与瘤周水肿区的低级别脑胶质瘤和高级别脑胶质瘤Cho/Cr和Cho/NAA的差异。结果 MRI扫描显示低级别脑胶质瘤和高级别脑胶质瘤的瘤周水肿区的水肿和肿瘤实质区的强化程度对比,差异均无统计学意义(均P>0.05)。1H-MRS扫描显示高级别脑胶质瘤的肿瘤实质区的Cho/Cr和Cho/NAA值与瘤周围水肿区的Cho/Cr值均高于低级别脑胶质瘤,差异均有统计学意义(均P<0.05)。而高级别脑胶质瘤和低级别脑胶质瘤瘤周水肿区的Cho/NAA值比较,差异无统计学意义(P>0.05)。结论在传统MRI扫描的基础上联合使用1H-MRS,可以提供定量的检测结果来评价肿瘤的恶性度,为脑胶质瘤做出准确的分级诊断。     

颅内疾病诊断中质子MRI波谱脂质峰升高的意义

目的探讨颅内疾病诊断中质子MRI波谱脂质(Lip)峰升高的意义。方法统计分析2012年1月至2014年1月收治的100例颅内肿瘤及非肿瘤性病变患者的临床资料。结果各种不同疾病类型Lip峰阳性率之间的差异均有统计学意义(均P<0.05)。高度恶性脑肿瘤组患者的胆碱/肌酸(Cho/Cr)、胆碱/N-乙酰天门冬氨酸(Cho/NAA)比值均明显良性病变组和低度恶性脑肿瘤组,差异有统计学意义(P<0.05),但良性病变组和低度恶性脑肿瘤组患者的Cho/Cr、Cho/NAA值差异无统计学意义(P>0.05)。结论质子MRI波谱Lip峰升高能够将不同病理变化有效反映出来,Lip峰联合Cho峰及常规MRI在颅内疾病诊断中发挥重要作用。     

利用深度学习提升肺癌调强质子治疗笔形束剂量计算准确性

目的:质子笔形束(PB)剂量计算可实现快速剂量计算,但在处理组织不均匀度大的区域时误差较大,而蒙特卡洛(MC)剂量计算是最精准的方法但非常耗时;深度学习技术可以通过学习PB和MC剂量分布之间的差异,将剂量计算准确度从PB水平提高到MC水平。方法:基于HD U-Net神经网络,开发了一个可将肺癌调强质子治疗患者的PB剂量...     

肿瘤运动对磁共振引导放射治疗剂量分布影响的研究

目的 旨在通过端到端测试验证磁共振直线加速器(MRI-Linac)剂量照射的准确性,评估自适应计划对不同运动模式剂量保证的可靠性.方法 使用磁共振兼容的运动模体(CIRS 008Z),设定6种运动模式进行端到端测试,在MR-linac(医科达Unity,1.5T)进行剂量照射,对比5种运动模式剂量与标准运动模式剂量的差...     

剂量计算公式总散射校正因子测量深度的研究

目的总散射校正因子Sc,p值是放射治疗处方剂量计算使用的一个重要参数,研究正确获得Sc,p值的方法。方法在射野等中心轴不同深度下对6、15MV能量的光子射线的Sc,p值进行测量。结果Sc,p值随测量深度不同而改变,最大差异为1%～7%。直接测量获得Sc,p值,其测量深度应取处方剂量计算公式中剂量归一点深度。若在其他深度下测量Sc,p值,可用推导公式计算获得Sc,p(fsz.g)。结论欲获得处方剂量公式中使用的Sc,p值,应重视正确的Sc,p值测量深度,可用直接测量法或间接计算法获得。     

磁共振成像引导颅内肿瘤微创治疗的优劣分析*

肿瘤微创治疗越来越受到临床医生和患者的重视。近年来,影像引导下的肿瘤物理、化学消融治疗和125I 粒子植入组织间近距离放疗已经成为治疗肿瘤的首选方法之一。磁共振成像（magnetic resonance imaging,MRI）具有CT、超声、数字减影血管造影机（digital subtraction angiography,DSA ）无法比拟的优越性,尤其对于颅内肿瘤的诊断及介入微创治疗更显示出其独特优势。然而,MRI 也具有伪影、消融范围、手术操作复杂等不足。本文旨在浅析颅内胶质瘤和转移瘤在MRI 引导下微创治疗的优劣及对策。     

脑胶质瘤氢质子磁共振波谱代谢物与Ki-67抗原的相关性及其应用价值

摘 要：［目的］ 探讨胶质瘤氢质子磁共振波谱（1-H magnetic resonance spectroscopy,1H-MRS）所示代谢物值与Ki-67抗原的相关性及其应用价值。［方法］ 回顾性分析83例术前行1H-MRS检查、术后病理学结果为脑胶质瘤的患者资料,对比分析胶质瘤实质部位主要代谢物N-乙酰天门冬氨酸（NAA）、胆碱（Cho）、肌酸（Cr）及其比值（Cho/Cr、Cho/NAA、NAA/Cr）与Ki-67表达的相关性。［结果］ Cho/Cr、Cho/NAA比值与Ki-67表达呈正相关(r=0.257,P=0.019;r=0.329,P=0.002),NAA/Cr比值与Ki-67表达呈负相关(r=-0.206,P=0.049);Lip出现率与Ki-67表达呈正相关（r=0.304,P=0.005）。［结论］ 1H-MRS检查的各代谢物值与Ki-67表达关系密切,可有效反应脑胶质瘤的增殖活性,其中Cho/NAA比值的诊断价值最高。     

质子技术儿童肿瘤治疗的前沿

"现代肿瘤治疗强调的是靶向治疗、个性化治疗、综合治疗,这已经成为肿瘤治疗的三大原则。"在几乎所有的肿瘤高层论坛研讨会上,都可以听到这样的呼吁,而其中,综合治疗又成为了重中之重。确实,对任何一种肿瘤的治疗方法都不应该单兵作战,多兵种的集团军"协作"才能让肿瘤这个强大的"敌人"完败。如今在临床中,医生还是更愿意把目     

CT值区间划分及用于治疗计划剂量计算研究

目的 探讨CT值变化对剂量计算影响,初步寻找一种解决MRI电子密度信息缺失方法。方法 选取头颈、胸部、盆腔部位肿瘤患者各10例CT图像,对各部位主要组织器官CT值随机采样,统计其平均值进行CT值区间划分。在瓦里安Eclipse TPS中构建虚拟模体,给予处方剂量1 Gy记录不同CT值下机器输出剂量,并分析不同CT值区间对剂量计算结果影响。选取5例宫颈癌患者IMRT计划,对靶区、OAR进行CT值分配形成新CT图像,在新CT图像上进行计划移植并与患者原CT图像结果进行剂量学参数比较。结果 通过区间法对CT值进行划分,并在剂量计算中验证,计算出人体不同组织对应的CT值区间为-100~100 HU,CT值变化对剂量计算的影响在3%以内。相同计划下新合成CT图像与原CT图像剂量学参数差异较小,PTV的D_max、D_mean、D_98%、D_95%、D_5%、D_2%均<3%,膀胱、直肠、小肠、股骨头、骨髓的D_max、D_mean均<2%。结论 CT值划分法对盆腔肿瘤治疗计划剂量计算结果影响在可接受范围内,对解决MRI电子密度信息缺失具有一定可行性。     

质子放疗独立剂量计算平台的搭建与验证北大核心CSCD

目的基于上海先进质子放疗设备(SAPT)水平固定束,利用开源剂量计算引擎搭建质子放疗独立剂量计算平台并验证该平台的准确性。方法通过测量SAPT水平固定束的绝对积分深度剂量以及空气中束斑大小,并结合蒙特卡洛模拟得到水中束斑大小增量,笔形束参数与剂量计算引擎相结合,搭建了适用于该水平固定束的剂量计算平台。计算平台精确性的验证主要通过绝对剂量验证和相对剂量验证实现。绝对剂量验证主要是比较单个立方体计划射野中心轴线上不同深度计算值和实测值的点对点误差。相对剂量验证主要是比较计算值和实测值的横向一维及二维相对剂量分布。同时,对单高斯束斑模型和双高斯束斑模型的精确性进行比较。结果计算值和实测值的点对点绝对剂量偏差在2%以内。3个立方体在中心深度的二维平面相对剂量分布的计算值与实测值的20%~80%半影宽度及半高全宽的偏差分别在1、2 mm以内。3个立方体计划及2个临床病例在中心深度的二维平面相对剂量分布的实测值与计算值的二维γ通过率(3 mm/3%)均>95%。双高斯束斑模型在剂量梯度变化较大或者射程较大的计划中相较于单高斯束斑模型计算得更准确。结论独立剂量计算平台的精确度能满足临床要求,可利用此平台研究其他剂量相关的问题。     

质子放疗独立剂量计算平台的搭建与验证

目的 基于上海先进质子放疗设备（SAPT）水平固定束,利用开源剂量计算引擎搭建质子放疗独立剂量计算平台并验证该平台的准确性。方法 通过测量SAPT水平固定束的绝对积分深度剂量以及空气中束斑大小,并结合蒙特卡洛模拟得到水中束斑大小增量,笔形束参数与剂量计算引擎相结合,搭建了适用于该水平固定束的剂量计算平台。计算平台精确性的验证主要通过绝对剂量验证和相对剂量验证实现。绝对剂量验证主要是比较单个立方体计划射野中心轴线上不同深度计算值和实测值的点对点误差。相对剂量验证主要是比较计算值和实测值的横向一维及二维相对剂量分布。同时,对单高斯束斑模型和双高斯束斑模型的精确性进行比较。结果 计算值和实测值的点对点绝对剂量偏差在2%以内。3个立方体在中心深度的二维平面相对剂量分布的计算值与实测值的20%~80%半影宽度及半高全宽的偏差分别在1、2 mm以内。3个立方体计划及2个临床病例在中心深度的二维平面相对剂量分布的实测值与计算值的二维γ通过率（3 mm/3%）均>95%。双高斯束斑模型在剂量梯度变化较大或者射程较大的计划中相较于单高斯束斑模型计算得更准确。结论 独立剂量计算平台的精确度能满足临床要求,可利用此平台研究其他剂量相关的问题。     

Anthropomorphic lung phantom based validation of in-room proton therapy 4D-CBCT image correction for dose calculation

PurposeVentilation-induced tumour motion remains a challenge for the accuracy of proton therapy treatments in lung patients. We investigated the feasibility of using a 4D virtual CT (4D-vCT) approach based on deformable image registration (DIR) and motion-aware 4D CBCT reconstruction (MA-ROOSTER) to enable accurate daily proton dose calculation using a gantry-mounted CBCT scanner tailored to proton therapy.MethodsVentilation correlated data of 10 breathing phases were acquired from a porcine ex-vivo functional lung phantom using CT and CBCT. 4D-vCTs were generated by (1) DIR of the mid-position 4D-CT to the mid-position 4D-CBCT (reconstructed with the MA-ROOSTER) using a diffeomorphic Morphons algorithm and (2) subsequent propagation of the obtained mid-position vCT to the individual 4D-CBCT phases. Proton therapy treatment planning was performed to evaluate dose calculation accuracy of the 4D-vCTs. A robust treatment plan delivering a nominal dose of 60 Gy was generated on the average intensity image of the 4D-CT for an approximated internal target volume (ITV). Dose distributions were then recalculated on individual phases of the 4D-CT and the 4D-vCT based on the optimized plan.Dose accumulation was performed for 4D-vCT and 4D-CT using DIR of each phase to the mid position, which was chosen as reference. Dose based on the 4D-vCT was then evaluated against the dose calculated on 4D-CT both, phase-by-phase as well as accumulated, by comparing dose volume histogram (DVH) values (D_mean, D_2%, D_98%, D_95%) for the ITV, and by a 3D-gamma index analysis (global, 3%/3 mm, 5 Gy, 20 Gy and 30 Gy dose thresholds).ResultsGood agreement was found between the 4D-CT and 4D-vCT-based ITV-DVH curves. The relative differences ((CT-vCT)/CT) between accumulated values of ITV D_mean, D_2%, D_95% and D_98% for the 4D-CT and 4D-vCT-based dose distributions were ?0.2%, 0.0%, ?0.1% and ?0.1%, respectively. Phase specific values varied between ?0.5% and 0.2%, ?0.2% and 0.5%, ?3.5% and 1.5%, and ?5.7% and 2.3%. The relative difference of accumulated D_mean over the lungs was 2.3% and D_mean for the phases varied between ?5.4% and 5.8%. The gamma pass-rates with 5 Gy, 20 Gy and 30 Gy thresholds for the accumulated doses were 96.7%, 99.6% and 99.9%, respectively. Phase-by-phase comparison yielded pass-rates between 86% and 97%, 88% and 98%, and 94% and 100%.ConclusionsFeasibility of the suggested 4D-vCT workflow using proton therapy specific imaging equipment was shown. Results indicate the potential of the method to be applied for daily 4D proton dose estimation.     

Towards offline PET monitoring of proton therapy at MedAustron

The characteristic depth-dose profile of protons traveling through material is the main advantage of proton therapy over conventional radiotherapy with photons or electrons. However, uncertainties regarding the range of the protons in human tissue prevent to exploit the full potential of proton therapy. Therefore, a non-invasive in-vivo dose monitoring is desired. At the ion beam center MedAustron in Wiener Neustadt/Austria, patient treatment with proton beams started in December 2016. A PET/CT is available in close vicinity of the treatment rooms, exclusively dedicated to offline PET monitoring directly after the therapeutic irradiation. Preparations for a patient study include workflow tests under realistic clinical conditions using two different phantoms, irradiated with protons prior to the scan in the PET/CT. GATE simulations of the C-11 production are used as basis for the prediction of the PET measurement. We present results from the workflow tests in comparison with simulation results, and by this, we demonstrate the applicability of the PET monitoring at the MedAustron facility.     

Neutrons in active proton therapy: Parameterization of dose and dose equivalent

Purpose

One of the essential elements of an epidemiological study to decide if proton therapy may be associated with increased or decreased subsequent malignancies compared to photon therapy is an ability to estimate all doses to non-target tissues, including neutron dose. This work therefore aims to predict for patients using proton pencil beam scanning the spatially localized neutron doses and dose equivalents.

Effect of anatomic motion on proton therapy dose distributions in prostate cancer treatment

PURPOSE: To determine the dosimetric impact of interfraction anatomic movements in prostate cancer patients receiving proton therapy. METHODS AND MATERIALS: For each of the 10 patients studied, 8 computed tomography (CT) scans were selected from sets of daily setup CT images that were acquired from a cohort of prostate cancer patients. The images were acquired in the treatment room using the CT-on-rails system. First, standard proton therapy and intensity-modulated radiation therapy (IMRT) plans were designed for each patient using standard modality-specific methods. The images, the proton plan, and the IMRT plan were then aligned to the eight CT images based on skin marks. The doses were recalculated on these eight CT images using beam from the standard plans. Second, the plans were redesigned and evaluated assuming a smaller clinical target volume to planning target volume margin (3 mm). The images and the corresponding plans were then realigned based on the center of volume of the prostate. Dose distributions were evaluated using isodose displays, dose-volume histograms, and target coverage. RESULTS: For the skin-marker alignment method, 4 of the 10 IMRT plans were deficient, whereas 3 of 10 proton plans were compromised. For the alignment method based on the center of volume of the prostate, only the proton plan for 1 patient was deficient, whereas 3 of the 10 IMRT plans were suboptimal. CONCLUSION: A comparison of passively scattered proton therapy and highly conformal IMRT plans for prostate cancer revealed that the dosimetric impact of interfractional anatomic motions was similar for both modalities.     

1H-MRS在脑胶质瘤诊治中的价值

1H-MRS通过对活体代谢物进行定量分析,可以较早地探测脑胶质瘤代谢异常。1H—MRS不仅为胶质瘤的诊断、鉴别诊断、分级、浸润范围及肿瘤预后判定等提供更加科学、精确及敏感的依据,更为临床的诊治开辟新的途径。     

Dosimetric impact of geometric distortions in an MRI-only proton therapy workflow for lung,liver and pancreas

In a radiation therapy workflow based on Magnetic Resonance Imaging (MRI), dosimetric errors may arise due to geometric distortions introduced by MRI. The aim of this study was to quantify the dosimetric effect of system-dependent geometric distortions in an MRI-only workflow for proton therapy applied at extra-cranial sites. An approach was developed, in which computed tomography (CT) images were distorted using an MRI displacement map, which represented the MR distortions in a spoiled gradient-echo sequence due to gradient nonlinearities and static magnetic field inhomogeneities.A retrospective study was conducted on 4DCT/MRI digital phantoms and 18 4DCT clinical datasets of the thoraco-abdominal site. The treatment plans were designed and separately optimized for each beam in a beam specific Planning Target Volume on the distorted CT, and the final dose distribution was obtained as the average. The dose was then recalculated in undistorted CT using the same beam geometry and beam weights. The analysis was performed in terms of Dose Volume Histogram (DVH) parameters.No clinically relevant dosimetric impact was observed on organs at risk, whereas in the target structure, geometric distortions caused statistically significant variations in the planned dose DVH parameters and dose homogeneity index (DHI). The dosimetric variations in the target structure were smaller in abdominal cases (ΔD_2%, ΔD_98%, and ΔD_mean all below 0.1% and ΔDHI below 0.003) compared to the lung cases. Indeed, lung patients with tumors isolated inside lung parenchyma exhibited higher dosimetric variations (ΔD_2% ≥ 0.3%, ΔD_98% ≥ 15.9%, ΔD_mean ≥ 3.3% and ΔDHI ≥ 0.102) than lung patients with tumor close to soft tissue (ΔD_2% ≤ 0.4%, ΔD_98% ≤ 5.6%, ΔD_mean ≤ 0.9% and ΔDHI ≤ 0.027) potentially due to higher density variations along the beam path. Results suggest the potential applicability of MRI-only proton therapy, provided that specific analysis is applied for isolated lung tumors.     

质子治疗横纹肌肉瘤的研究进展

横纹肌肉瘤(RMS)是儿童最常见的软组织肉瘤.放疗已成为RMS治疗的首选治疗方案之一,但可诱发严重的急性和晚期不良反应.质子治疗近年来越来越多的被应用于治疗RMS中.质子治疗安全有效,无严重不良反应.与常规射线比较,质子治疗RMS有物理学优势,可以更好地降低正常组织的受照剂量,提高患者生命质量.仍需要更多前瞻性研究和长期随访的临床结局,明确质子治疗应用于治疗RMS是否在晚期并发症的发生率和严重程度等方面优于光子治疗.