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1.
    
In the last 60 years, hadron therapy has made great advances passing from a stage of pure research to a well-established treatment modality for solid tumours. In this paper the history of hadron therapy accelerators is reviewed, starting from the first cyclotrons used in the thirties for neutron therapy and passing to more modern and flexible machines used nowadays. The technical developments have been accompanied by clinical studies that allowed the selection of the tumours which are more sensitive to this type of radiotherapy. This paper aims at giving a review of the origin and the present status of hadron therapy accelerators, describing the technological basis and the continuous development of this application to medicine of instruments developed for fundamental science. At the end the present challenges are reviewed.  相似文献   

2.
    
GoalProton treatment monitoring with Positron-Emission-Tomography (PET) is based on comparing measured and Monte Carlo (MC) predicted β+ activity distributions. Here we present PET β+ activity data and MC predictions both during and after proton irradiation of homogeneous PMMA targets, where protons were extracted from a cyclotron.Methods and materialsPMMA phantoms were irradiated with 62 MeV protons extracted from the CATANA cyclotron. PET activity data were acquired with a 10 × 10 cm2 planar PET system and compared with predictions from the FLUKA MC generator. We investigated which isotopes are produced and decay during irradiation, and compared them to the situation after irradiation. For various irradiation conditions we compared one-dimensional activity distributions of MC and data, focussing on Δw50%, i.e., the distance between the 50% rise and 50% fall-off position.ResultsThe PET system is able to acquire data during and after cyclotron irradiation. For PMMA phantoms the difference between the FLUKA MC prediction and our data in Δw50% is less than 1 mm. The ratio of PET activity events during and after irradiation is about 1 in both data and FLUKA, when equal time-frames are considered. Some differences are observed in profile shape.ConclusionWe found a good agreement in Δw50% and in the ratio between beam-on and beam-off activity between the PET data and the FLUKA MC predictions in all irradiation conditions.  相似文献   

3.
PurposePositron emitting isotopes such as 11C and 10C can be used for vital dose verification in hadron therapy. These isotopes are produced when the high energy 12C primary beam particles undergo nuclear reactions within the patient.MethodsWe discuss a model for calculating cross sections for the production 11C in 12C + 12C collisions, applicable at hadron therapy energies.ResultsGood agreement with the available cross section measurements is found for 12C(−1n), though more detailed, systematic measurements would be very valuable.ConclusionsNuclear structure plays a crucial role in the reactions of light nuclei, particularly when those reactions are peripheral and involve only a few nucleons. For such reactions, nuclear structure has a strong influence on the energy and angular distribution of the cross section, and is an important consideration for reliable dose verification using 11C in hadron therapy.  相似文献   

4.
    
Stopping powers of H, He, H2, and H2O targets for antiprotons have been calculated using a convergent close-coupling method. For He and H2 targets electron–electron correlations are fully accounted for using a multiconfiguration approximation. Two-electron processes are included using an independent-event model. The water molecule is described using a neon-like structure model with a pseudo-spherical potential. Results are tabulated for the purpose of Monte Carlo simulations to model antiproton transport through matter for radiation therapy.  相似文献   

5.
产NDM-1(New Delhi Metallo-β-lactamase 1,Ⅰ型新德里金属β-内酰胺酶)细菌是新近报道的一种泛耐药细菌,由于对绝大多数常用抗生素均耐药,又被称为超级细菌.目的:建立一种可快速检测泛耐药细菌NDM-1基因的Taqman探针实时荧光定量PCR法.方法:根据NDM-1基因序列,设计引物和Ta...  相似文献   

6.
    
AimThe purpose of this study is to optimize treatment planning in carbon ion radiotherapy, taking into account the effect of tumour hypoxia.BackgroundIn conventional hadron therapy, the goal is to create a homogenous dose in the tumour area and, thus, achieve a uniform cell survival level. Since the induction of a specific damage to cells is directly influenced by the level of hypoxia in the tissue, the varying oxygen pressure in the different regions of hypoxic tumours would disrupt the uniformity of the cell survival level.Materials and methodsUsing the Geant4 Monte Carlo Code, the physical dose profile and dose-averaged linear energy transfer were calculated in the tumour. Then, the oxygen enhancement ratio in different areas of the tumour were compared with different pressures.ResultsModulations of radiation intensities as well as energies of ion beams were calculated, both considering and disregarding the effect of hypoxia, and the required dose profiles were compared with each other. Cell survival levels were also compared between the two methods. An equation was obtained for re-modulating the beams in the presence of hypoxia, and radiation weighting factors were extracted for the beam intensities.ConclusionThe results show that taking the effect of hypoxia into account would cause the reduction of average doses delivered to the tumour tissues up to 1.54 times. In this regard, the required dose is reduced by 1.63 times in the healthy tissues before the tumour. This will result in an effective protection of healthy tissues around the tumour.  相似文献   

7.
ob基因编码的leptin蛋白在调节生物体能量平衡中起到重要作用。本研究应用Taqman探针real time PCR技术对高原鼠兔ob基因的组织分布进行检测。通过提取不同组织总RNA,经DNase I消化后,用随机引物进行反转录合成cDNA,采用特异性Taqman探针和引物分别对ob基因及β-actin基因进行实时定量PCR扩增,对不同组织中ob基因和β-actin基因的初始拷贝数之比进行比较。结果表明ob基因在脑、心脏、肺、肝脏、脾脏、肾脏、骨骼肌、脂肪组织中均有表达,其中以白色脂肪组织中ob基因表达量最高,其次为心脏和肺,表达量最低的是肝脏和肾脏。  相似文献   

8.
    
AimThe purpose of this study was to investigate the crosstalk effects between adjacent pixels in a thin silicon detector with 50 um thickness.BackgroundThere are some limitations in the applications of detectors in hadron therapy. So it is necessary to have a detector with concurrent excellent time and resolution. In this work, the GEANT4 toolkit was applied to estimate the best value for energy cutoff in the thin silicon detector in order to optimize the detector.Materials and MethodsGEANT4 toolkit was applied to simulate the transport and interactions of particles. Calculations were performed for a thin silicon detector (2 cm × 2 cm×0.005 cm) irradiated by proton and carbon ion beams. A two-dimensional array of silicon pixels in the x-y plane with 100 um × 100 um × 50 um dimensions build the whole detector. In the end, the ROOT package is used to interpret and analyze the resultsResultsIt is seen that by the presence of energy cutoff, pixels with small deposited energy are ignored. The best values for energy cutoff are 0.01 MeV and 0.7 MeV for proton and carbon ion beams, respectively. By applying these energy cutoff values, efficiency and purity values are maximized and also minimum output errors are achieved.ConclusionsThe results are reasonable, good and useful to optimize the geometry of future silicon detectors in order to be used as beam monitoring in hadron therapy applications.  相似文献   

9.
设计了一种针对院外心血管病患者的远程心电监护系统,包括便携式监护终端和医院监护中心。其特点在于可对身处院外、自由活动的心血管病患者进行远程、实时、连续的监护,同时获得被监护患者的地理位置信息。已完成的整体调试结果表明,本系统不仅能及时发现异常心电图并进行干预,而且还可根据地理位置信息对突发急病的患者进行快速救治。该系统是院内监护系统功能的延伸,有良好的临床应用前景。  相似文献   

10.
    

Aim

Design of a numerical method for creating spread-out Bragg peak (SOBP) and evaluation of the best parameter in Bortfeld Model to this aim in oxygen ion therapy.

Background

In radiotherapy, oxygen ions have more biological benefits than light beams. Oxygen ions have a higher linear energy transfer (LET) and larger relative biological effectiveness (RBE) than lighter ones.

Materials and methods

For the design of the spread-out Bragg peak (SOBP) for oxygen beam, we designed a numerical method using the Geant4 Monte Carlo simulation code, along with matrix computations.

Results

The profiles of the Bragg Peak have been calculated for each section in the target area by the Geant4 tool. Then, in order to produce SOBP smoothly, a set of weighting factors for the intensity of oxygen ion radiation in each energy was extracted through a numerically designed method. This method was tested for producing SOBP at various widths and at different depths of a phantom. Also, weighting factors of intensity for producing a flat SOBP with oxygen ions were also obtained using the Bortfeld model in order to determine the best parameters. Then, the results of the Bortfeld model were compared with the outcomes of the method that was developed in this study.

Conclusions

The results showed that while the SOBP designed by the Bortfeld model has a homogeneity of 92–97%, the SOBP designed by the numerical method in the present study is above 99%, which in some cases even closed to 100%.  相似文献   

11.
    
Radiosurgery was introduced over half a century ago for treatment of intracranial lesions. In more recent years, stereotactic radiotherapy has rapidly advanced and is now commonly used for treatments of both cranial and extracranial lesions with high doses delivered in a few, down to a single fraction. The results of a workshop on Particle radiosurgery: A new frontier of physics in medicine held at Obergurgl, Austria during August 25–29 2013 are summarized in this issue with an overview presented in this paper. The focus was laid on particle radiosurgery but the content also includes current practice in x-ray radiosurgery and the overarching research in radiobiology and motion management for extracranial lesions. The results and discussions showed that especially research in radiobiology of high-dose charged-particles and motion management are necessary for the success of particle radiosurgery.  相似文献   

12.
    
The use of carbon ion beams in cancer therapy (also known as hadron therapy) is steadily growing worldwide; therefore, the demand for more efficient dosimetry systems is also increasing because daily quality assurance (QA) measurements of hadron radiotherapy is one of the most complex and time consuming tasks. The aim of this study is to develop a two-dimensional dosimetry system that offers high spatial resolution, a large field of view, quick data response, and a linear dose–response relationship.We demonstrate the dose imaging performance of a novel digital dose imager using carbon ion beams for hadron therapy. The dose imager is based on a newly-developed gaseous detector, a well-type glass gas electron multiplier. The imager is successfully operated in a hadron therapy facility with clinical intensity beams for radiotherapy. It features a high spatial resolution of less than 1 mm and an almost linear dose–response relationship with no saturation and very low linear-energy-transfer dependence. Experimental results show that the dose imager has the potential to improve dosimetry accuracy for daily QA.  相似文献   

13.
14.
    
This paper investigates the possibility to efficiently use a wireless sensor network (WSN) to help preventing poaching in tiger habitats and to identify tigers’ movement patterns that later on can provide valuable information about their territorial behavior, hunting and reproduction. The same method can be successfully applied to track other mammals in the wild. We concluded that these objectives can be achieved in a 2000 sq. km area with only 2000 module sensors that work in the ZigBee standard, that operates on the IEEE 802.15.4 physical radio specification.  相似文献   

15.
在充满生存竞争的动物世界,视觉的伪装与反伪装现象随处可见,视觉反伪装的原理是什么?本文对Reichardt的图形-背景相对运动分辨模型加以发展,提出了视觉反伪装功能的运动图象滤波器模型。为了检验此模型,我们建立了一个生物学似真的实时运动信息加工神经网络电子装置,实现了实时、高分辨运动目标图象滤波。与Mead的人工视网膜的运动目标图象检测功能相比,检测的运动目标图象的分辨率有很大提高,而噪声水平显著降低,克服了人工视网膜的一些局限性。  相似文献   

16.
钠米颗粒介导质粒DNA转染体外真核细胞   总被引:2,自引:0,他引:2  
DNA传递是基因表达与功能研究及其医学应用的重要技术,安全高效的DNA传递一直是研究者期待的目标。利用一种新的阳离子多聚物脱乙酰甲壳胺16介导重组质粒pcDNA3vp1转染COS7细胞,RTPCR可检测到目的基因vp1在mRNA水平的表达,实时定量PCR结果表明其转染效率介于脂质体与磷酸钙法之间,同时还对转染条件进行了探讨。DNA结合分析发现脱乙酰甲壳胺16能够与DNA形成核酸纳米颗粒,提高DNA稳定性,促进真核细胞转染效率的提高。这些结果表明脱乙酰甲壳胺16确能做为一种新型的非病毒纳米DNA传递载体,并将可能在基因表达与功能研究及基因治疗等领域发挥重要作用 。  相似文献   

17.
Background and objectivesSepsis is one of the major factors for both term and preterm babies with morbidity and mortality. On the basis of recent clinical trials, altered circulating micro-RNAs (miRNAs) may serve as possible biomarkers in sepsis for diagnosis and prognosis. The aim of this research is to assess the diagnostic and prognostic biomarkers of miRNA 15b and miRNA 378a for neonatal sepsis.Subjects & methodsThis study was carried out 25 neonates with sepsis admitted to neonatal ICU of Menoufia University Hospital and 25 healthy controls from February 2019 to May 2020. The relative quantification (RQ) of miRNA-15b and miRNA-378a expression was assessed using real time PCR technique. Results: Our results demonstrated that patients with sepsis had significantly higher level of MiRNA-15b than the healthy volunteers. On the other hand, patients with sepsis had significantly lower level of MiRNA-378a than the healthy volunteers. The ROC curve showed that the serum MiRNA-15b was a significant discriminator of sepsis with a combined sensitivity and specificity of 76% and 88% with cutoff point of 3.24. In addition, serum MiRNA-378a was a significant discriminator of sepsis with a combined sensitivity and specificity of 60% and 88% with cutoff point of 0.361. The miRNA-15b expression significantly correlated positive with respiratory rate (r =0.415,p =0.039), WBCs (r = 0.408, p =0.043), and CRP (r =0.407, p=0.043). Likewise, miRNA-378a expression significantly correlated negative with respiratory rate (r =-0.415p =0.024), WBCs (r =- 0.442, p =0.027), and CRP (r =- 0.459, p=0.021).ConclusionBoth MiRNA 15b and 378a are promising biomarker for neonatal sepsis.  相似文献   

18.
目的应用NASBA方法制备SIV/SHIV RNA定量测定标准品。方法应用NASBA方法直接扩增SIVmac251病毒gag基因上1476~1685之间的片段,扩增的RNA产物(RS-NASBA)纯化后10倍系列稀释,测定定量曲线、标准曲线,测定该标准品的稳定性和重复性。结果应用Qiagen公司QuantiTect SYBR GREEN RT-PCRKit,该标准品可精确定量到2.033×10 copies/μL。结论外标准品RS.NASBA纯度高,稳定性好,可用于定量测定SIV/SHIV RNA拷贝数。  相似文献   

19.
Real time RT-qPCR检测规范化   总被引:1,自引:0,他引:1  
  相似文献   

20.
Modern techniques as ion beam therapy or 4D imaging require precise target position information. However, target motion particularly in the abdomen due to respiration or patient movement is still a challenge and demands methods that detect and compensate this motion. Ultrasound represents a non-invasive, dose-free and model-independent alternative to fluoroscopy, respiration belt or optical tracking of the patient surface. Thus, ultrasound based motion tracking was integrated into irradiation with actively scanned heavy ions. In a first in vitro experiment, the ultrasound tracking system was used to compensate diverse sinusoidal target motions in two dimensions. A time delay of ∼200 ms between target motion and reported position data was compensated by a prediction algorithm (artificial neural network). The irradiated films proved feasibility of the proposed method. Furthermore, a practicable and reliable calibration workflow was developed to enable the transformation of ultrasound tracking data to the coordinates of the treatment delivery or imaging system – even if the ultrasound probe moves due to respiration. A first proof of principle experiment was performed during time-resolved positron emission tomography (4DPET) to test the calibration workflow and to show the accuracy of an ultrasound based motion tracking in vitro. The results showed that optical ultrasound tracking can reach acceptable accuracies and encourage further research.  相似文献   

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