立体定向放射治疗计划输出剂量的验证

本文简单介绍对加速器的立体定向治疗计划的输出剂量进行的验证测量，其测量结果和治疗计划预制输出剂量在-1．1％内吻合。并利用胶片法测量了立体定向治疗计划的输出剂量的分布，其测量结果与治疗计划输出剂量分布的80％等剂量曲线面积重合率为94％，得到较满意的结果。     

放射治疗中治疗计划输出剂量的验证

本文简单介绍利用德国PTW公司所生产的31006型(0.015cc)、30001型电离室(0.6cc)和按AAPM54号报告要求所自制的φ160mm球型有机玻璃模体及普通放疗测量所应用的200mm×200mm×100mm方形水模体,对加速器的立体定向辐射治疗计划的输出剂量进行验证测量,其结果在1%内吻合.     

放射治疗中治疗计划输出剂量的验证

本文简单介绍利用德国PTW公司所生产的 310 0 6型 (0 .0 15cc)、30 0 0 1型电离室 (0 .6cc)和按AAPM 5 4号报告要求所自制的16 0mm球型有机玻璃模体及普通放疗测量所应用的 2 0 0mm× 2 0 0mm× 10 0mm方形水模体 ,对加速器的立体定向辐射治疗计划的输出剂量进行验证测量 ,其结果在 1%内吻合     

X刀剂量场的测量

本介绍利用德国PTW公司所生产的MP3型治疗射线束分析仪自动测量X刀剂量辐射场的组织最大比（TMR）和离轴比（OAR）,并采用自制的球形有机玻璃模体和小体积探测器模拟立体定向放射治疗的全部过程,验证测量了头部X刀、体部X刀的治疗计划实施输出剂量。     

X刀剂量场的测量与研究

由日本三菱ＭＬ－２００ＭＤＸ信号直线加速器（１０ＭＶ）与国产ＢＪＸ－Ｉ型三维立体定向治疗系统匹配组成Ｘ刀装置,介绍其辐射场剂量学有关参数的测量,其中包括利用小体积（０．０１５ｃｃ）的针尖电离富对不同射野直径（Φ５￣４５ｍｍ）的组织最大比（ＴＭＲ）,总散射输出因子（Ｓｔ）的测量;使用胶片法测量离轴比（ＯＡＲ）;采用Φ１６０ｍｍ有机玻璃球形模体和组织等效头形模体测量辐射场的剂量分布,并用此法验证了治疗     

IAEA TRS-398临床剂量学应用

为降低临床放射治疗剂量测量的不确定度,讨论并对比了直接测量处方剂量:水吸收剂量的方法TRS-398报告应用于临床的优势。通过介绍在不同种类射线下直接测量水吸收剂量的条件与方法,汇总目前基于TRS-398报告测量方法的部分实验数据,结果表明:TRS-398报告方法测量剂量与277报告方法测量剂量在允许测量不确定度以内一致,表明398报告方法测量结果可靠,且满足临床剂量输出不确定度5%(k=1)以内的要求。这一结果为更新临床放射治疗剂量输出测量的方法提供理论依据。     

TQ-2000型多通道剂量仪

本文介绍了最新研制的“TQ-2000型多通道剂量仪”基本原理和技术性能。主要应用包括：患者重要器官在放疗时的剂量测量和剂量监测;全身照射入口剂量和出口剂量及透射率测量;体内中心剂量测量;三维适形调强放疗剂量分布测量和相应的计划系统剂量分布检验;放疗设备和后装机系统稳定性测量;辐射场分析及剂量分布测量等。它与体模配套使用,能进行体内外剂量测量。     

体部立体定向放射外科 γ辐射治疗源校准方法的研究

体部立体定向放射外科γ辐射治疗源是当前治疗癌症的一种辐射源,属于强检范畴,然而目前国内没有体部立体定向放射外科γ辐射治疗的法定检定依据。本文探讨了体部立体定向放射外科γ辐射治疗源的主要计量性能指标及其技术要求,提出了具体的校准方法。     

胶片剂量仪与半导体探测器在小野剂量数据测量中的比较分析

小照射野的建模数据对于调强放射治疗和立体放射治疗十分重要。在加速器使用6MV光子束条件下,采用胶片与0.01cm³的半导体探头,在IBA Blue Phantom 2水箱与固体水中,测量0.6cm×0.6cm至10.0cm×10.0cm照射野的百分深度剂量(PDD)曲线、profile、点剂量等数据,并计算射野总散射因子Scp。测试结果表明:对于PDD曲线,不同的照射野情况下,半导体探头与胶片在建成区测得数据基本吻合,在水深2～10cm测量结果存在微小偏差,当水深超过10cm以后差距明显(达7%);对于profile曲线,不同照射野下,胶片与半导体探头测量数据无明显差异,但胶片具有更好的空间分辨率,体现在半影区剂量跌落更明显;半导体探头、胶片剂量仪测得的点剂量与计划系统计算相同深度的点剂量比较,差异明显(最大误差分别为-2.7%、12%)。分析得出:不同的测量探头,对小野物理数据测量的准确性可能存在很大差异;胶片剂量仪具有优越的空间分辨率,但是胶片的吸收剂量范围有限,具有能量和方向依赖性。     

μc—FB型智能化薄膜剂量读数仪

本文介绍用于辐射加工中剂量监测的μC-FB 型智能化薄膜剂量读数仪,它能直接读出显色薄膜的辐照剂量数值,具有多种输入、输出功能。读出精度为±1%,可测光密度值上限为2.000,数字显示,在测量剂量范围为5～150kGy 时,线性相关系数为0.999.     

Medical application of 3-D polymer gel dosemeter evaluated by nuclear magnetic resonance

A polymer-gel dosemeter, which can be evaluated by nuclear magnetic resonance (NMR), was prepared and then a few samples were homogeneously irradiated by a Leksell gamma knife using an 18 mm collimator (60Co gamma photons) to obtain a calibration curve (NMR 1/T2 response to absorbed dose). To measure dose distribution from the Leksell gamma knife, a testing flask tilled with the gel was fixed in the head phantom and then irradiated based on a calculated treatment plan. Evaluation of dosemeters was performed on a Siemens EXPERT 1T NMR scanner. Dose profiles in X, Y and Z coordinates through the ellipsoidal shape of the dose distribution were obtained to compare experimental results from the irradiated phantom with the treatment planning system calculations. The use of a polymer-gel dosemeter for a verification of stereotactic procedures has some unique advantages which can be summarised as follows: (1) the dosemeter itself is tissue equivalent, (2) three-dimensional dose distributions can be measured, (3) the dosemeter allows patient's procedures to be simulated without any limitations.     

Study of the degree of III conditioning of the phase space of pencil-beam radiotherapy using singular value decomposition

Dose distribution optimization algorithms are necessary in pencil-beam radiotherapy to exploit efficiently the multiple parameters of this powerful irradiation technique. We propose as an optimization technique singular value decomposition (SVD) analysis, which allows the measurement of ill conditioning of the stereotactic radiotherapy inverse problem and yields optimal weights for conformal treatment. Our approach to dose distribution optimization is to recover estimates of the minibeams weights from well-defined previsional dose matrices to study the influence of the different parameters on the stereotactic radiotherapy inverse procedure. The adjustment of the different parameters of the stereotactic irradiation to the “SVD optimizer” procedure is realized taking into account the ratio of the quality reconstruction to the calculation time. It will permit a more efficient use of the SVD optimizer in clinical applications with real three-dimensional lesions. We show the efficiency of the SVD optimizer in analyzing and predicting ill conditioning in stereotactic radiotherapy and in recognizing the topography of the different beams to create an optimal vector containing the beam weights (reconstructed weighting vector).     

Evaluation of the population dose to the UK population from the National Health Service Breast Screening Programme

In the United Kingdom National Health Service Breast Screening Programme (NHSBSP), women aged between 50 and 70 y are invited for mammography every 3 y. Screening histories for each woman, over four screening rounds, were analysed. Data from five screening programmes were used to select 57 425 women into the study. Cases were selected on the basis of being between the ages of 50 and 53 at the start of the NHSBSP (i.e. between 1989 and 1992). Assessment of the outcome for each screening round for each woman involved assigning a simple outcome code. Each of the possible pathways through the four screening rounds was analysed. This comprises of 500 possible pathways. This data enabled the following information to be determined: (i) The number of times a woman attended the screening programme. (ii) The number of women referred for assessment at each screening round. This information may be used to deduce the population dose to this group of women averaged over four screening rounds. Patient doses have been monitored since the programme's inception and are typically 4.5 mGy for two-view screening. It is possible to determine the mean glandular dose received by this cohort of women over four screening rounds by multiplying the number of examinations by the mean glandular dose for a typical woman. Allowance has to be made for the number of projections taken at each screening round. Once a woman has been screened, she may be invited back for further assessment if an abnormality is found on her mammogram. A stereotactic attachment is used to determine where to place the biopsy device. Although the dose received during a normal screening mammogram is well known, the dose for a stereotactic procedure and other assessment procedures is less well known, partly because only a small part of the breast is directly irradiated during stereotaxis. However, the woman may have multiple exposures during this stage. A prospective survey of doses was completed to deduce the mean glandular dose at the first assessment stage and during stereotaxis. Numbers of films, including magnification films taken at first-stage assessment were established in the North East of England and Scotland by means of a postal survey. Average total mean glandular dose was deduced using previous survey data for the screening programme and a multiplying factor to allow for magnification film dose. On average 1.6 full field and 0.15 collimated contact films are taken for each woman (with 2.25 and 0.75 mGy film(-1)), 1.0 full field and 0.9 collimated magnification views. The mean magnification film dose to the assessed breast was 5.0 and 1.7 mGy for a collimated magnification film. A survey of 134 women at screening centres in the North East of England was performed to deduce the mean glandular dose from digital stereotaxis which is almost universally used in breast screening. A typical woman received a dose to the assessed breast of 4.5 mGy with a range of 1.3-17 mGy. This data may be used to deduce the total mean glandular dose over four screening rounds including the assessment stages. The estimated mean glandular dose to a typical woman invited to the screening programme is approximately 16 mGy, when allowance for attendance rate and assessment rate over each screening round is made. The mean glandular dose to the population is approximately 4700 Sv y(-1).     

Patient skin dosimetry in interventional cardiology in the Czech Republic

In this study, skin dosimetry of patients undergoing interventional cardiology procedures is presented. Three hospitals were included. Two methods were used for skin dosimetry--radiochromic dosimetry films and reconstruction of skin dose distribution based on examination protocol. Maximum skin doses (MSD) obtained from both methods were compared for 175 patients. For patients for whom the film MSD was >1 Gy, the reconstruction MSD differed from the film MSD in the range of ± 50 % for 83 % of patients. For remaining patients, the difference was higher and it was caused by longer fluoroscopy time. For 59 patients for whom the cumulative dose was known, the cumulative dose was compared with the film MSD. Skin dosimetry with radiochromic films is more accurate than the reconstruction method, but films do not include X-ray fields from lateral projections whilest reconstructions do.     

Specific absorbed fractions in thyroid diagnostics and treatment: Monte Carlo calculation with PENELOPE

In nuclear medicine, diagnostic and therapy procedures in which a certain radiopharmaceutical is administered to a patient are performed. An important point is the determination of the dose absorbed by the important organs of the patient due to these procedures. This dose depends on the particular radionuclide used and the so-called specific absorbed fractions. In this work, by means of Monte Carlo (MC) simulation, the specific absorbed fractions in case the thyroid gland acts as a source organ and for photon energies between 30 keV and 2 MeV have been determined. The computer code PENELOPE has been used as well as the adult male mathematical phantom provided with the distribution of this code. Three different simulation types were carried out. In one of them, only photon transport was considered. In the other two, electron transport was included, doing a detailed and a mixed simulation. In general, the fractions were estimated with uncertainties <9 %, for the mixed and detailed simulations, and <3 %, for the simulation in which only photons are included. For some target organs and, especially for energies <100 keV, the uncertainties found were larger. The results obtained here have been compared with those obtained by other authors using other MC codes. A good agreement has been found in 80 % of the cases.     

Inverted organic solar cells with ZnO nanowalls prepared using wet chemical etching in a KOH solution

We report on the photovoltaic (PV) performances of inverted organic solar cells (IOSCs) that were fabricated from PCBM:P3HT polymer with a ZnO thin film and ZnO nanowalls as electron transport and hole block layers. ZnO thin film on ITO/glass substrate was deposited using a simply aqueous solution route. ZnO nanowall structures were obtained via wet chemical etching of ZnO thin films in a KOH solution. The power conversion efficiency (PCE) of the IOSC with ZnO nanowalls was significantly improved by 44% from 1.254% to 1.811% compared to that of the IOSC with ZnO thin film. The short circuit current in IOSCs fabricated with the ZnO nanowalls was increased mainly due to the increase in the charge transport interface area, as a result of enhancement in the PCE. This work suggests a method for fabricating efficient PV devices with a larger charge transport area for future prospects.     

Interactive decision support in radiation therapy treatment planning

This paper proposes the use of an interactive decision support system to guide the treatment planning process for external beam radiation therapy. Based on multicriteria optimisation our research treatment planning software CARINA calculates efficient (also called Pareto optimal) treatment plans. These are stored in a database and accessed for evaluation by the treatment planner. The interactive component consists of navigation among the pre-calculated plans using free search, fine search and exact search as well as sensitivity analysis, which extracts dose dependence information for all structures from the plan database. As a result, plan quality is improved by finding advantageous trade-offs in competing treatment plans, trial-and-error is avoided, and effectiveness of treatment planning is increased.     

水性油墨用室温交联丙烯酸酯乳液的研究

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸为共聚单体,双丙酮丙烯酰胺(DAAM)为功能单体,采用半连续法乳液聚合技术,合成了含有酮羰基的聚丙烯酸酯乳液。以己二酸二酰肼为交联剂,获得的丙烯酸酯乳液在室温贮存时不产生交联反应,而在干燥时由于体系pH值发生变化,在酸的催化下可固化成膜。结果表明,加入3%的DAAM制得的丙烯酸酯乳液,固含量达50%左右,粒径主要分布在68.1 nm左右,且分布范围较窄,室温交联胶膜透明度、光泽度高,成膜速度快,各项性能优异。     

125I密封籽源水中吸收剂量分布的测量

用热释光剂量计对125I密封籽源在水中的剂量分布进行具有量值溯源性的测量,结果表明,125II密封籽源在水中的剂量分布随着离源距离的增加而快速衰减,同时受照角度对剂量分布也有一定的影响。模拟实验有助于改进放射性籽源植入治疗的剂量准确性和安全性。对测量误差和实验方法也进行了有益的讨论。