某医院新建辐射治疗中心的旋转式头部伽玛刀治疗装置环境防护监测与评价

目的对旋转式头部伽玛刀治疗装置及治疗室的辐射安全进行评价。方法测定旋转式头部伽玛刀治疗装置的泄漏辐射剂量测定治疗室内、外环境在治疗和非治疗状态下的剂量分布。结果距治疗系统机头表面5cm处各方向的剂量率在0.18～0.80μGy/h的范围内分布,距源1m处为0.25～2.60μGy/h。在治疗状态下,治疗室屏蔽墙外各测量点的剂量率为0.19～0.67μGy/h。结论旋转式头部伽玛刀治疗装置的泄漏辐射剂量符合国家标准要求。     

移动式加速器术中放射治疗的辐射防护与安全评价

目的 评估移动式加速器术中放射治疗(IORT)的辐射防护与安全状况,为IORT临床应用中的辐射安全提供指导.方法 以某医院拟用的1台MOBETRON移动式加速器及其场所为研究目标,确定IORT的工作负荷及场所外围人员的年剂量管理目标值,估算极端情况下IORT室外围的辐射水平和人员所受的剂量,核算IORT治疗场所的辐射屏蔽.结果 该IORT治疗室在仅采用相当于普通X射线诊断装置的屏蔽条件下,治疗室外与靶不同距离关注位置的剂量率为:东墙外35～78 μSv/h;南墙外89 μSv/h,西墙外70 ～ 84 μSv/h,北墙外75～106 μSv/h; IORT室楼下普通治疗室64 μSv/h,室顶外围空间为45μSv/h.估算出年累积出束5h时场所外围职业人员的年剂量最高为0.53 mSv,公众所受年剂量低于0.1 mSv,均满足剂量管理目标值的要求.加速器IORT设备及场所设置有相应的安全联锁、防护设施与管理措施,可有效制约设备运行照射时人员误入和误留IORT室的风险.结论 在普通手术室中施行移动式加速器IORT时,在工作负荷极小的条件下采取针对低能辐射的屏蔽防护可达到剂量管理目标要求,但应相对固定IORT场所,并根据工作负荷和剂量率控制要求对治疗室增设相应的屏蔽.     

三维适形联合体部伽玛刀治疗局部晚期非小细胞肺癌的临床研究

目的研究三维适形放疗(3DCRT)联合体部伽玛刀治疗局部晚期非小细胞肺癌(NSCLC)的疗效和毒副作用。方法对46例局部晚期NSCLC患者采用3DCRT联合体部伽玛刀治疗,3DCRT:每次2Gy,每天一次,共60Gy/30次;体部伽玛刀:每次5Gy,隔日一次,共20Gy/4次。结果 45例患者近期总有效率为62.2%(28/45),1、2年总生存率分别为68.9%(31/45)和37.8%(17/45),中位生存期为13.6个月。早期放射反应为放射性食管炎、放射性肺炎,多为Ⅰ～Ⅱ度。晚期放射反应主要为放射性肺纤维化,脊髓未观察到晚期放射反应。结论 3DCRT联合体部伽玛刀治疗局部晚期NSCLC近期疗效好,毒副作用轻,其远期疗效和晚期放射损伤有待进一步观察评价。     

医用回旋加速器辐射剂量检测与评价

目的：检测医用回旋加速器环境辐射水平及工作人员个人剂量，检验其对环境、公众及相关工作人员的安全性。方法：以住友HM12型回旋加速器为检测对象，使用多功能辐射仪及热释光剂量计测定环境辐射剂量、个人剂量水平。结果：加速器室与迷路门口^y射线辐射水平为96．16uSv／h，中子辐射水平为85．09uSv／h，迷路与控制室门口、控制室操作台、加速器室墙外及屋顶的辐射水平达到或接近本底水平，回旋加速器操作人员人均年剂量当量为2．21mSv。结论：加速器室环境辐射剂量、操作人员个人剂量水平远低于国家标准水平，应消除对回旋加速器操作的恐惧心理，但同时也要搞好放射防护管理。     

某医院192Ir近距离后装治疗机房辐射防护设计

目的探讨某医院拟新建192Ir近距离后装治疗机房辐射防护设计的可行性,有效控制职业病危害,保障辐射安全。方法依据国内外相关技术规范和标准,按辐射防护的基本原则对后装治疗机房辐射防护设计进行剂量估算和评价。结果近距离后装治疗机房各防护墙厚度均符合要求,防护门设计符合要求。后装治疗机房墙体计算厚度(混凝土)为:北墙595 mm,东墙595 mm,南墙479 mm,西墙595 mm,顶棚主墙2 282 mm,顶棚488 mm;防护门铅板厚度7 mm。结论后装机房各侧墙体、顶棚、防护门的屏蔽防护厚度均能够满足防护要求。     

螺旋断层放射治疗机房的防护设计与分析

目的掌握螺旋断层放射治疗机房的辐射水平,制订合理可行的辐射屏蔽与防护设计方案,为TOMO装置临床应用的辐射安全提供保障。方法以某医院的1台Tomotherapy Hi-Art螺旋断层放射治疗装置为研究对象,依据设备的性能参数,参照NCRP No.151报告和GBZ/T 201.2等技术标准以及AAPM No.148中相应的质量控制细则,确定TOMO机房的屏蔽与安全防护设计规划,并评估其防护效果。结果 TOMO机房屏蔽方案为:东、西防护墙和室顶为95cm重晶石;南墙为70cm重晶石;迷路内外墙分别为(70～30)cm重晶石和(30～70)cm重晶石;防护门为8mm铅。机房外围辐射水平估算结果表明,南墙外设备夹层通道的辐射剂量率最高为8.89μGy/h,其次为机房地下电缆沟处(3.25μGy/h);防护门外最高为1.6μGy/h。推算出机房外围放射工作人员所受年剂量最高为0.27mSv,公众可能受到的最高剂量均不高于0.03mSv/a。结论 TOMO装置治疗机房可主要考虑对泄漏辐射的屏蔽设计,同时应根据装置实际的照射参数、工作负荷和治疗机房的场所条件进行相应的防护效果分析。     

体部伽玛刀图像引导技术的发展

体部立体定向放射治疗（SBRT）是立体定向放射外科（SRS）技术和临床应用的自然延伸,是一种在精确图像引导下的大剂量低分次的放射治疗方法。体部伽玛刀是中国自主研发的创新放疗设备,把伽玛射束治疗从头部延伸至体部。在近15年的技术发展和临床实践中,体部伽玛刀沿用了传统的体部框架定位模式,由于缺少足够定位精度,限制了其作为SBRT设备在临床上的广泛使用。近年来,图像引导定位技术开始应用于体部伽玛刀,将为体部伽玛刀SBRT规范治疗开启崭新一页。本文介绍了体部伽玛刀图像引导定位的原理、方法、试验和初步应用。     

基于蒙特卡罗方法的质子治疗室屏蔽防护探讨

目的 探讨质子治疗室屏蔽防护材料和屏蔽厚度的选择,积累质子治疗室屏蔽防护经验,为质子治疗室的建设提供科学依据。方法 采用基于蒙特卡罗方法的FLUKA程序建立质子治疗室的屏蔽计算模型,模拟质子治疗室的辐射场分布,对质子治疗室的屏蔽进行优化。结果 厚度为250 cm混凝土控制室墙外30 cm处周围剂量当量最大为3.12 μSv/h,改变屏蔽方案为5 cm钢板（机房侧）+237 cm混凝土+8 cm聚乙烯（控制室侧）后,周围剂量当量最大值为1.43 μSv/h,调整材料位置后,治疗室控制室墙外30 cm周围剂量当量率最大为3.95 μSv/h。结论 质子治疗室辐射场中,主要是中子和γ射线,中子对剂量当量的贡献占绝大部分比重。且质子治疗室辐射场中主要以高能中子和快中子为主。因此其屏蔽防护主要考虑中子防护,在屏蔽材料的选择上应充分考虑辐射场的中子能量。     

放射治疗恶性肿瘤的效果探索

放射治疗是治疗恶性肿瘤的主要方法之一,已经专门为治疗癌症诞生了一百多年。放射治疗是利用各类加速器所产生的不同能量的X射线、电子、中子、质子、重离子以及放射源释放出的伽玛射线（如钴60治疗机、头、体部伽玛刀）来杀灭肿瘤细胞。     

体部γ刀治疗非小细胞肺癌的剂量学分布及正常组织的保护

目的：探讨分析体部γ刀在治疗非小细胞肺癌小病灶时的剂量分布及正常组织的受量情况。方法：选取10例非小细胞肺癌患者,入组条件：病灶大小≤5 cm,10例患者分别设计体部γ刀计划和三维适形计划,分析放疗计划中PTV最小剂量、平均剂量,正常组织肺的受量情况。结果：γ刀组PTV最小剂量、最大剂量、平均剂量分别为56.6%、99.8%、76.1%,肺V20、V25、V30、V35分别为7.02%、5.11%、4.24%、3.02%;适形组PTV最小剂量、最大剂量、平均剂量分别为94.0%、104.5%、100.2%,肺V20、V25、V30、V35分别为14.08%、10.20、8.42%、7.02%。结论：针对非小细胞肺癌≤5 cm的病灶,体部γ刀在保护正常组织上优于适形放疗,可提高放疗剂量,是一种治疗局部小病灶有效且理想的放疗方法。     

体部伽马刀治疗的质量控制和质量保证

目的:探讨体部伽马刀治疗过程中的质量控制与质量保证。方法:采用真空垫固定患者体位,CT扫描定位,通过HIS网络传输到治疗计划系统,进行靶区勾画、计划设计与验证,体部伽马刀治疗。结果:明显提高局部肿瘤控制率,降低周围正常组织和器官的放射并发症。结论:通过提高质量控制与质量保证水平,可以增加局部肿瘤的控制率,降低正常组织并发症。     

Evaluation of Bremsstrahlung radiation dose in stereotactically radiocolloid therapy of cystic craniopharyngioma tumors with <Superscript>32</Superscript>P radio-colloid

Over 90% of craniopharyngeal brain tumors are cystic, which enables the injection of beta emitters such as phosphorus-32 (³²P) radio-colloid into cysts for their treatment. The aim of this study was to evaluate the clinical and theoretical modelling of Bremsstrahlung radiation dose resulting from stereotactic radio-colloid therapy of cystic craniopharyngioma tumors with ³²P. ³²P radio-colloid with appropriate activity concentration was injected to a head phantom, and then the Bremsstrahlung radiation spectrum and planar images were obtained using a gamma camera. Both phantom and gamma camera were simulated using MCNPX code, and the results were compared with practical results. Bremsstrahlung radiation spectrum was measured using a handheld gamma spectrometer for two patients treated with stereotactic radio-colloid therapy with ³²P in different positions and compared to Monte Carlo simulation. Results of counting and determining sensitivity coefficients in the air and the attenuating environment were obtained. Also, comparing the counting sensitivity from practical and simulation methods indicated the agreement of the data between the two methods. Comparison of the spectra from different positions around patient’s head indicated the ability to use this detector to quantify the activity in the operating room. Selection of the spectrum is important in Bremsstrahlung radiation imaging. We can take advantage of spectrometry measurement using gamma camera, handheld gamma spectrometer for patient, and theoretical modeling with Monte Carlo code to evaluate radiopharmaceutical distribution, leakage, as well as estimate activity and predict therapeutic effects in other adjacent structures and ultimately optimize radio-colloid therapy in cystic craniopharyngeal patients.     

Influence of seed extract of Syzygium Cumini (Jamun) on mice exposed to different doses of gamma-radiation

The radioprotective activity of the hydroalcoholic extract of jamun seeds (SCE) was studied in mice exposed to different doses of gamma radiation. The mice were injected with 0, 5, 10, 20, 40, 60, 80, 100, 120, 140 or 160 mg/kg body weight of SCE, before exposure to 10 Gy of gamma radiation, to select the optimum dose of radiation protection. The 80 mg/kg SCE was found to offer highest protection, therefore, further studies were carried out using this dose. The drug was more effective when administered through the intraperitoneal route at equimolar doses than the oral route. Since higher survival was observed for the i.p. route (50%), than the oral route (29.2%), all other studies were carried out by injecting SCE intraperitoneally. The mice treated with 80 mg/kg body weight SCE intraperitoneally before exposure to 6, 7, 8, 9, 10 and 11 Gy of gamma radiation showed reduction in the symptoms of radiation sickness and mortality at all exposure doses and caused a significant increase in the animal survival when compared with the concurrent double distilled water (DDW) + irradiation group. The SCE treatment protected mice against the gastrointestinal as well as bone marrow deaths and the DRF was found to be 1.24.     

自屏蔽回旋加速器辐射剂量测定

目的检测自屏蔽回旋加速器的辐射剂量,以保障放射工作人员的安全。方法应用手提便携式辐射测量仪检测加速器室、放化实验室以及靶的拆卸和重装过程中的辐射剂量。结果加速器室、放化实验室以及靶的拆卸和重装过程中的辐射剂量在规定的安全范围之内。结论回旋加速器自屏蔽系统、合成热室、分装防护屏等具有良好的辐射屏蔽效果。     

An experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy

A radiation streaming experiment has been carried out at the Takasaki Ion Accelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicability of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerator operating in the intermediate energy region. The data suggest that it is mandatory to estimate the gamma ray dose equivalent rate in a labyrinth, which is dominated by the secondary gamma rays due to the neutron capture reaction.     

Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC

A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed ²⁸Al, ²⁴Na, ⁵⁴Mn and ⁶⁰Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is ²⁸Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several ²⁸Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received.     

非均匀自制模体的临床可应用性实验分析

目的 对自制等效于人体多种组织密度模体,进行临床质控可应用性实验分析。方法 自制密度接近骨骼、肺、空腔及软组织的模体材料,并组合制作非均匀验证模体,然后对器官等效材料的电子密度进行比较。选用本科收治的10例肺癌患者,分别在该自制模体和固体水模体上进行调强计划剂量验证,比较2种模体在剂量验证领域的特点,并分析自制模体在TPS上的计算值与实测值的剂量学差异,采用SPSS 21.0软件进行统计分析。结果 使用自制模体和固体水模体进行剂量验证,γ通过率（3 mm/3%）均在90%以上。应用自制模体进行剂量验证的测量值,比使用固体水模体时偏大,测量值最大偏差为11.5%。2种模体间的剂量验证γ通过率AD组和RD组差异无统计学意义（P> 0.05）。结论 自制模体符合临床应用的精度要求,可应用在放射治疗计划验证。     

某院乳腺机房屏蔽厚度的计算与评价

目的通过计算,设法找到乳腺机房所需屏蔽厚度,以评估机房屏蔽设计厚度的适宜性。方法依据辐射防护的基本原则及放射卫生有关法规标准,按次级辐射屏障厚度计算公式计算出乳腺机房所需屏蔽材料厚度。结果乳腺机房屏蔽计算厚度很小,其屏蔽设计厚度远大于计算厚度(所需厚度)。结论乳腺机房四周墙体和顶棚设计厚度应减小至建筑所需最小厚度,防护门可改为符合标准的防盗门,满足辐射防护的要求。     

医用电子直线加速器治疗机房入口辐射剂量分析

目的 探究加速器机房入口辐射剂量,指导机房入口防护检测。方法 利用FLUKA程序构建加速器机头及机房模型,模拟加速器在10 MV和600 cGy/min条件下,比较不同机架角度、照射条件和迷路情况下机房入口内侧的辐射剂量率。结果 不同迷路内墙厚度和机架角条件下,有水箱时入口剂量率明显大于无水箱情况。迷路内墙厚度为1 800 mm,机架角为90°时入口剂量率最大。迷路内墙厚度为1 000 mm,机架角为0°和180°时,入口剂量率明显大于其他情况。迷路内墙为1.80 m、机架角为90°、有水箱、迷路内入口宽为1 400～2 200 mm时,机房入口处剂量率在（82.26±48.95）～(314.09±96.34)μSv/h。结论 加速器机房入口处的剂量主要来自于有用线束在患者体表的散射和泄漏辐射,入口剂量率随迷路内口宽度递增。在入口防护检测时,机架角度的选取要考虑迷路内墙厚度,在不明确情况下对4个角度进行检测,保证检测结果的全面和准确。     

Gamma radiation dosimetry using a NaCl:Ba(T) thermoluminescent phosphor

A detailed examination is presented of the thermoluminescence (TL) characteristics of untreated and heat-treated pure and Ba-doped NaCl exposed to gamma radiation at room temperature. The NaCl:Ba (10(-2) molar fraction) phosphor quenched from 750 degrees C, designated as NaCl:Ba(T), is found to give a pronounced TL output with a well-defined glow peak around 220 degrees C (peak III) along with other peaks at lower temperatures. It is suggested that the TL centre associated with glow peak III is comprised of an impurity-vacancy dipole with a negative ion vacancy in its vicinity. The TL centres are presumed to be located in the dislocation region. The dosimetric properties of peak III after gamma irradiation have also been examined. It is observed that most of the basic requirements of an efficient TLD material are fulfilled by the phosphor.