Magnetron Sputtered CsPbCl3 Perovskite Detectors as Real-Time Dosimeters for Clinical Radiotherapy

The aim of this study is to investigate the feasibility of manufacturing thin real-time relative dosimeters for clinical radiotherapy (RT) with potential applications for transmission monitoring in vivo dosimetry and pre-treatment dose verifications. Thin (≈1 μm) layers of a high sensitivity, wide bandgap semiconductor, the inorganic perovskite CsPbCl₃, have been grown for the first time by magnetron sputtering on plastic substrates equipped with electrode arrays. Prototype devices have been tested in real-time configuration to evaluate the dose delivered by a 6 MV photon beam from a linear accelerator. Linearity of the charge with the dose has been verified over three order of magnitudes, linearity of the current signal with the dose rate has been also successfully tested in the range 0.5-4.3 Gy/min. The combination of high sensitivity per unit volume and wide bandgap provides high signal-to-noise ratios, up to 70, even at moderate applied voltages. The Schottky diode configuration allows the detector to operate without bias voltage (null bias).The blocking-barrier structure allows to confine the active volume within sub-millimetric sizes, a quite attractive feature in view to increase granularity and achieve the high spatial resolutions required in modern RT techniques. All the above-mentioned features indeed pave the way to a novel generation of flexible, transmission, real time dosimeters for clinical radiotherapy.     

Actinic ultraviolet exposures to humans assessed with a dosimetric technique

A spectrum evaluator based on a system of four materials has been applied to the evaluation of actinic ultraviolet exposures to humans. The exposures were evaluated between early morning and near noon in summer and the actinic irradiances calculated ranged from 3 muW cm-2 to 5 muW cm-2. Simultaneously, the broad band irradiances which induced the actinic exposures and/or the biologically effective exposures for any other process may be evaluated with the method. The erythemal exposures ranged from 13 to 23 muW cm-2. The method can be useful both for solar UV studies and research with UV lamps which possess radiation wavelengths shorter than 295 nm where the actinic and erythemal action spectra differ significantly.     

两台451P型电离室剂量仪时间常数的比较研究

目的 比较2台451P型电离室剂量仪的时间常数,探讨时间响应修正公式的应用。方法 X射线机采用两个剂量率水平进行曝光,较高剂量率水平采用不同的测量模式进行测量,记录仪器测量的周围剂量当量率,根据RC电路的时间响应修正公式进行数据拟合,求出仪器的时间常数τ。结果 2台451P型电离室剂量仪0~5μSv/h量程时间常数τ值分别为（3 476.4±124.9） ms和（3 676.4±144.4） ms,0~50 μSv/h自动转换量程τ值分别为（2 051.6±249.5） ms和（2 047.0±271.9） ms,0~50 μSv/h固定量程时间常数τ值分别为（1 123.8±85.9） ms和（1 242.0±91.8） ms。结论 2台451P型电离室剂量仪的时间常数无统计学差异,但与操作手册的给定值有统计学差异,应合理选择曝光时间和测量模式进行防护检测,并使用已检定的时间常数进行响应时间修正。     

4种诊断X射线剂量仪能量响应的比较

目的 对常用的几种进口和国产的医用诊断X射线剂量仪的能量响应特性进行比较研究。方法在标准X射线辐射场中采用替代法完成剂量测量。结果国产RD-98诊断剂量仪与进口剂量仪能量响应性能均符合IEC要求。结论半导体探测器的诊断剂量仪与空气电离室剂量仪具有相同的能响变化范围。     

DSA冠脉造影致医护人员辐射剂量的研究

目的 研究放射介入医生在进行DSA冠状动脉造影术时,医生各层面皮肤表面的吸收剂量,并对介入手术过程中的辐射剂量进行分析,为介入工作人员实行介入手术时,在防护问题方面,提供一些指导性的建议。方法 根据冠脉造影时的曝光条件,使用DSA设备对带有热释光剂量计的仿真人体模型进行曝光,再根据已经制作好的标准曲线,使用BR2000D,对医护人员(第一术者和第二术者)各高度层面铅衣前/后的皮肤表面吸收剂量进行测量,并使用SPSS17.0软件进行统计学分析。结果 第一术者眼晶状体、甲状腺、乳腺和性层面腺吸收剂量分别为0.261、0.301、0.226和0.243 mGy,第二术者眼晶状体、甲状腺、乳腺和性腺吸收剂量分别为0.275、0.303、0.309和0.328 mGy。结论 在进行冠状动脉造影术时,第一术者在移动式铅屏风的作用下,乳腺和性腺层面范围内的皮肤表面吸收剂量明显低于第二术者,眼晶状体和甲状腺层面范围与第二术者无显著性差异。另外,对介入医生来说,第一术者的防护情况的关注度一般很高,对第二术者防护措施更应该得到加强。     

眼晶体、指环剂量计的部分剂量学性能实验测试研究

目的 比较国产与进口眼晶体、指环剂量计的部分性能测试结果,掌握眼晶体、指环剂量计的部分剂量学性能指标.方法 依据IEC 62387-2012和GBZ 128-2019中性能要求,分别使用国产和进口热释光探测器开展了眼晶体剂量计和指环剂量计在光子响应下的性能对比实验;测试进口眼晶体和指环剂量计在相同照射条件下照射2次的剂...     

心血管介入手术中操作者职业照射的临床调查

目的 调查心血管介入手术中操作者的有效剂量。方法 利用热释光方法对某省属三级甲等医院进行的24例冠状动脉血管造影术(CA)或者继续行经皮穿刺腔内冠状动脉成形术(PTCA)或者继续行冠状动脉支架植入术(PICAS)和4例起搏器植入术(PT)的操作者进行了体表剂量测定和有效剂量估算。结果 在CA、PTCA、PICAS中平均手术时间为(19.2±6.3)min,操作者平均每次手术的有效剂量为(4.1±0.9)μSv,在没有铅衣防护的条件下,为(52.2±15.5)μSv;而PT平均手术时间为(14.1±4.6)min,操作者平均每次手术的有效剂量为(5.5±1.4)μSv,在没有铅衣防护的条件下,为(220±42)μSv。结论 应努力提高操作者的技术水平,缩短荧光照射时间,保证医护人员防护设施的配置,以降低操作者的受照剂量。     

TLD-LiF热释光剂量计在冠状动脉血管内再狭窄剂量学的应用研究

目的 研究粉末,3 mm×3 mm×0.4 mm TLD方片,3 mm×3 mm×0.2 mm TLD方片和1 mm×1 mm×1 mm TLD方片4种TLD-LiF剂量计在近距离放射治疗冠状动脉再狭窄时的应用特性。方法 用上述4种剂量计测量³²P液体球囊(直径为3 mm,长度为20 mm)和¹⁰³Pd放射性支架(直径为20 mm,长度为13 mm)的表面剂量和径向剂量,并将测量结果与蒙特卡罗代码(MCNP4B)的计算结果进行比较。结果 粉末和方片剂量计的测量结果有一定的差异,经过方片粉末修正因子修正后,3 mm×3 mm×0.2 mm TLD方片的结果与粉末一致。结论 3 mm×3 mm×0.2 mmTLD方片可以测量冠状动脉再狭窄近距离放射治疗的径向剂量和表面剂量分布。     

Eye Lens Radiation Doses to Miscentering Patients and Health-Care Staff From Head Computed Tomography

The purposes of this study were to assess the effect of patient vertical miscentering on eye lens radiation doses in patients who have undergone head computed tomography (CT) and to measure the absorbed dose to the eye lens in health-care staff who remain in the CT room during the procedure. All measurements were performed in phantoms. Nanodot™ optically stimulated luminescence dosimeters were used to measure radiation doses. For the assessment of the effect of patient vertical miscentering, CT scans were obtained at six different table heights. The radiation doses in the eye lens of health-care staff received when working at three different locations in the CT room were measured. Correction coefficients were applied to determine equivalent dose, Hp(3), in the eye lens. The results revealed that the positioning of patients off the CT scan isocenter during head CT may result in a significantly increased eye lens dose. The phantom eye lens doses can be increased by 43.7% (70 mGy), and image noise increased when the table was 5 cm below the isocenter due to the effect of the bow tie filter and eyes being irradiated directly by the primary beam for a greater proportion of the tube rotation. An estimated eye lens dose of ≤0.1-0.2 mSv was found in phantoms simulating health-care staff, with the dose depending on positioning of the phantom. Health-care staff in the room during CT scans are at risk of a significant eye lens dose, particularly if positioned posterior to the gantry.