Intensity modulated radiation therapy with simultaneous integrated boost based dose escalation on neoadjuvant chemoradiation therapy for locally advanced distal esophageal adenocarcinoma

AIM:To evaluate impact of radiation therapy dose escalation through intensity modulated radiation therapy with simultaneous integrated boost(IMRT-SIB).METHODS:We retrospectively reviewed the patients who underwent four-dimensional-based IMRT-SIBbased neoadjuvant chemoradiation protocol.During the concurrent chemoradiation therapy,radiation therapy was through IMRT-SIB delivered in 28 consecutive daily fractions with total radiation doses of 56 Gy to tumor and 5040 Gy dose-painted to clinical tumor volume,with a regimen at the discretion of the treating medical oncologist.This was followed by surgical tumor resection.We analyzed pathological completion response(p CR) rates its relationship with overall survival and event-freesurvival.RESULTS:Seventeen patients underwent dose escalation with the IMRT-SIB protocol between 2007 and 2014 and their records were available for analysis.Among the IMRT-SIB-treated patients,the toxicity appeared mild,the most common side effects were grade 1-3 esophagitis(46%) and pneumonitis(11.7%).There were no cardiac events.The Ro resection rate was 94%(n = 16),the p CR rate was 47%(n = 8),and the postoperative morbidity was zero.There was one mediastinal failure found,one patient had local failure at the anastomosis site,and the majority of failures were distant in the lung or bone.The 3-year diseasefree survival and overall survival rates were 41%(n = 7) and 53%(n = 9),respectively.CONCLUSION:The dose escalation through IMRT-SIB in the chemoradiation regimen seems responsible for down-staging the distal esophageal with well-tolerated complications.

Estimation of enhanced low dose rate sensitivity mechanisms using temperature switching irradiation on gate-controlled lateral PNP transistor

The mechanisms occurring when the switched temperature technique is applied,as an accelerated enhanced low dose rate sensitivity(ELDRS)test technique,are investigated in terms of a specially designed gate-controlled lateral PNP transistor(GLPNP)that used to extract the interface traps(Nit)and oxide trapped charges(Not).Electrical characteristics in GLPNP transistors induced by ^(60)Co gamma irradiation are measured in situ as a function of total dose,showing that generation of Nit in the oxide is the primary cause of base current variations for the GLPNP.Based on the analysis of the variations of Nit and Not,with switching the temperature,the properties of accelerated protons release and suppressed protons loss play critical roles in determining the increased Nit formation leading to the base current degradation with dose accumulation.Simultaneously the hydrogen cracking mechanisms responsible for additional protons release are related to the neutralization of Not extending enhanced Nit buildup.In this study the switched temperature irradiation has been employed to conservatively estimate the ELDRS of GLPNP,which provides us with a new insight into the test technique for ELDRS.

Measurement of the Effective Dose Radiation at Radiology Departments of Some Hospitals in Duhok Governorate

During operating of the X-ray machines, if the protection of X-ray rooms is insufficient, not only the patient but also clinical staffs as well as public are exposed to high X-ray dosage and they are affected from X-ray related to the dose level. In the present survey, by testing the radiological leakage and scatter from X-rays machines in radiology departments of 7 randomly selected hospitals in Duhok governorate, the effects dose of X-ray to the both control panel area and the patients waiting or visiting area who are located near the radiography room, were measured. The dose was recorded for a range of peak kilovoltage (kVp) and mAs values to find efficiency of shielding materials (barriers) of radiography rooms for different X-rays level. The measurements were performed at one meter above the ground surface which was the same height of X-rays tube by using Gamma Scout dosimeter. From the measurement results, it was seen that the most hospitals barriers (doors and walls) were not appropriate to the standards except 2 hospitals. The maximum effective doses were measured in uncontrolled area of Khazer hospital which was 82.48 ± 0.73 mSv·yr-1 that was much more than the reference dose limits and in controlled area of Haval Banda Zaroka hospital which was 12.98 ± 0.16 mSv·yr-1. In result, the knowledge about the radiation dose affecting the radiologists and public in the selected hospitals was obtained, and by informing the radiologists and the hospitals managements, the necessary regulations would be planned.

Natural background radiation dose rate levels and incidences of reproductive abnormalities in high radiation area in Abeokuta, Southwestern Nigeria

A 10 y (1999-2008) birth records from two public and most accessible maternity hospitals locally in the city of Abeokuta, Nigeria were used to investigate the possible association of high outdoor gamma radiation exposure on reproductive abnormalities in the city. From the delivery record of 11,923 births in the period under study, a total number of 485 incidences of reproductive abnormalities were recoded. These incidences comprise 228 multiple births, 190 still births and, 67 premature births. Using the available terrestrial gamma radiation exposure data for the city and different reproductive abnormalities, regression assessment was carried out using the Pearson Product Moment (PPM) correlation statistics. The correlation showed that the incidences of reproductive abnormalities and the radiation dose levels were negatively correlated and correlation coefficient values were very low for each of the reproductive abnormalities considered. Factors such as socio-economic potentials of patients, dietary and other environmental factors may have substantial influence on the reproductive defects in the area other than radiation. However, the present study has added to the radiometric information needed in understanding the relationship between natural outdoor radiation exposure and occurrences of reproductive abnormalities in areas of high radiation in the country.

Radiation dose to patients during endoscopic retrograde cholangiopancreatography

Endoscopic retrograde cholangiopancreatography (ERCP) is an important tool for the diagnosis and treatment of the hepatobiliary system. The use of fluoroscopy to aid ERCP places both the patient and the endoscopy staff at risk of radiation-induced injury. Radiation dose to patients during ERCP depends on many factors, and the endoscopist cannot control some variables, such as patient size, procedure type, or fluoroscopic equipment used. Previous reports have demonstrated a linear relationship between radiation dose and fluoroscopy duration. When fluoroscopy is used to assist ERCP, the shortest fluoroscopy time possible is recommended. Pulsed fluoroscopy and monitoring the length of fluoroscopy have been suggested for an overall reduction in both radiation exposure and fluoroscopy times. Fluoroscopy time is shorter when ERCP is performed by an endoscopist who has many years experience of performing ERCP and carried out a large number of ERCPs in the preceding year. In general, radiation exposure is greater during therapeutic ERCP than during diagnostic ERCP. Factors associated with prolonged fluoroscopy have been delineated recently, but these have not been validated.

Scatter Radiation Dose Assessment in the Radiology Department of Cape Coast Teaching Hospital-Ghana

During the operation of an X-ray machine, if the radiation protection of X-ray room is insufficient, not only the patient but also clinical staffs as well as public are exposed to high X-ray exposures. In this research work, leakage and scattered radiations were measured from X-ray machine in the radiology department of Cape Coast Teaching hospital in the Cape Coast Municipality of Ghana. The scattered radiation exposures of X-rays in some selected areas within the facility were measured. The X-ray machine was operated for a range of kilo voltage peaks of kVp 77, 70, 63 and 66 with intensities 20, 6.3 and 8.0 mAs, which represents the main technique factors of some body parts such as chest, lumbar spine and extremities during radiographic examinations. The measurements were performed using a RADOS-120 Universal survey meter. The radiation doses rates measured in the various locations in the Radiology Department of Cape Coast Teaching Hospital of Ghana were in the range of 0.10 μSv/hr to 0.12 μSv/hr. These values were all within the background measurement of 0.10 μSv/hr. Moreover, there were no risks of high radiation doses to patients, staffs and people visiting the X-ray department. The results obtained indicated that within the radiology department of the Hospital, all the selected locations were very safe to patients, occupational workers and the general public which could be attributed to adequate shielding in the facility.

Reduction of the Radiation Dose by Decreasing the Tube Current without Degradation of Low-Contrast Detectability on Abdominal Multi-Detector Row CT: A Phantom-Based Study

As use of the lowest acceptable radiation dose during routine diagnostic imaging is important, we determined the optimal tube current without degradation of low-contrast detectability on abdominal multi-detector row CT (MDCT). CT scanning was performed with a Catphan®?500 phantom. The optimal tube current was 300 mA on 64-MDCT and 160 mA on 8-MDCT, with a fixed voltage of 120 kV. Reduction of the radiation dose in abdominal CT scanning by lowering the tube current proved to be feasible.

Natural Radiation Dose and Geomagnetic Effect

Earth keeps getting bombarded by high-energy particles that originate in the outer space and in Sun. Cosmic radiation in Earth’s atmosphere consists of a photon and directly ionizing component and a neutron component. Charged particles of cosmic radiation are deflected by the geomagnetic field that is more expressed at the equator than near the poles. Photon radiation was measured by Radiameter ESM FH 40G-L10 at 26 main meteorological stations in all parts of Croatia. The correlation between the photon dose rate and latitude was examined, as well as multiple correlations for the photon dose, latitude and altitude. The obtained positive correlation coefficients were statistically significant. The neutron component of the cosmic radiation was measured by series of nuclear track-etched detectors, at the same meteorological stations during one year period. The dependence of the neutron dose rate on the altitude was found and the associated equation of the linear regression was derived. Relation between the values of neutron dose N and altitude h, showed significant dependence of the neutron dose on altitude. However, the correlation of neutron dose and geographic (geomagnetic) latitude was not statistically significant, probably due to a small range of geographic latitudes for the measuring stations in Croatia.

“Radiation Hormesis”中的剂量率效应

为了揭示不同剂量率Ｘ射线低剂量全身照射对低剂量辐射兴奋效应（ＲａｄｉａｔｉｏｎＨｏｒｍｅｓｉｓ）的影响，采用不同剂量率（１２．７ｍＧｙ／ｍｉｎ和０．２Ｇｙ／ｍｉｎ）对Ｂａｌｂ／ｃ小鼠进行低剂量全身照射，研究了低剂量辐射兴奋效应中的剂量率效应。结果表明：采用不同剂量率Ｘ射线照射同一剂量时，所引起的生物效应不同。剂量率为１２．７ｍＧｙ／ｍｉｎ时，脾细胞３Ｈ－ＴｄＲ参入量对ＣｏｎＡ的反应性明显增强，尤其以７６．７ｍＧｙ和１０５．５ｍＧｙ照射组最为显著（Ｐ＜０．０１），表现出明显的辐射免疫兴奋效应。而剂量率为０．２Ｇｙ／ｍｉｎ时，在１０５．５ｍＧｙ以内，脾细胞３Ｈ－ＴｄＲ参入量对ＣｏｎＡ的反应性无明显变化。该结果提示：高剂量率低剂量全身照射不能引起低剂量辐射兴奋效应。

An Accelerated Simulation Method for ELDRS of Bipolar Operational Amplifiers Using a Dose-Rate Switching Experiment

Through different dose-rate switching evaluation methods,the radiation-response rules of operational amplifiers are studied when the irradiation dose rate is switched from high to low under different radiation temperatures and total doses. The experimental results indicate that the response characteristics could be affected by the switching total doses, irradiation temperatures,and dose rates individually or together. Accelerated evaluation on the ELDRS can be realized by adopting a proper dose-rate switching method. Meanwhile, the irradiation time can also be reduced. Finally, the mechanisms of the difference between various radiation responses are analyzed.

Secondary and activated X(γ)radiation of SPHIC particle therapy facility

We report the secondary X(γ)radiation from the accelerator in a normal operating state and activated X(γ)radiation from the accelerator devices when the accelerator stops operating in the cancer treatment facility of the Shanghai Proton and Heavy Ion Center(SPHIC).These radiation measurements show us the structural radiation distribution along the beam lines and devices inside the accelerator room when the beam is on and off and can support the radiation protection design of the accelerator facility used for cancer treatment and help evaluate the accumulated radiation dose in the case of an emergency,such as a personal safety system failure or a radiation accident.The radiation dose rate measured in this facility shows that the facility is safe from the radiation protection point.After shooting the quality assurance(QA)beam,the radiation dose rate in the treatment room was also measured to investigate the radiation dose space distribution and decay time dependence.In addition,the time period before safely entering the treatment room after determining the shooting of the QA beam is recommended to be approximately 5 min.

High Dose Rate (HDR) Brachytherapy for Mycosis Fungoides of the Wrist

Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma accounting for approximately half of all cutaneous T-cell lymphomas. Radiation therapy is an effective treatment for early stage MF and has been shown to result in long-term disease-free intervals, with even curative potential. Radiation is also effective as palliative treatment for the localized lesion resistant to the topic or other treatments. In the current study, we report using high dose rate (HDR) radiation treatment for a patient with resistant mycosis fungoides involving the wrist. We report a convenient treatment with an ideal radiation dose distribution, and a excellent clinical outcome.

Absorbed Dose to Water Rate in a Cyberknife VSI System Reference Field Using Ionization Chambers and Gafchromic Films

This work investigated the absorbed dose to water rate under reference conditions in a Cyberknife VSI system using radiochromic films EBT3 and MD-V3 and three ionization chambers: an Exradin A12 and two FC65P Welhöfer Scanditronix with different serial numbers. The correction factor,, was studied using a Varian iX linac and the Cyberknife system. The measurements in the Varian iX were performed in a 10 × 10 cm2 field, 10 cm depth in liquid water at 90 cm and 70 cm SSD and in a 5.4 × 5.4 cm2 field, 10 cm depth at 70 cm SSD to simulate the Cyberknife conditions. In the Cyberknife system, measurements were performed using ionization chambers and both film types at 70 cm SSD and 10 cm depth in its 6 cm diameter reference field. The results indicate that ?is independent of the dosimeters and the evaluation methods. Maximum differences of 0.22% - 0.55% (combined uncertainties of 1.22% - 1.98%, k = 1) are obtained on ?using Varian iX, whereas discrepancies of 2.08% - 2.09% (combined uncertainties of 1.87% - 2.13%, k = 1) are observed using the Cyberknife system. Given the agreement between detectors and the combined standard uncertainties, the data from Varian iX could be considered the most accurate and consequently a weighted average factor of 0.902 ± 0.006 could be used for the Cyberknife VSI system reference field. Within measurement uncertainties, the absorbed dose rate measured in the Cyberknife VSI system reference field was found to be independent of the dosimeters used. These results suggest that the absorbed dose measured at a point within a given field size should be the same, regardless the dosimeter used, if their dosimetric characteristics are well known. This highlighted the importance of performing dosimetry by controlling all parameters that could affect the dosimeter response. One can conclude that radiochromic film dosimetry can be considered as an appropriate alternative for measuring absorbed dose to water rate.

Dose-rate effects of low-dropout voltage regulator at various biases

A low-dropout voltage regulator,LM2941,was irradiated by ^(60)Coγ-rays at various dose rates and biases for investigating the total dose and dose rate effects.The radiation responses show that the key electrical parameters, including its output and dropout voltage,and the maximum output current,are sensitive to total dose and dose rates, and are significantly degraded at low dose rate and zero bias.The integrated circuits damage change with the dose rates and biases,and the dose-rate effects are relative to its electric field.

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.

Bioflavonoids as Important Component of Biological Protection from Ionizing Radiation

New advances in the area of deciphering the mechanism for a possible modification of the biological effects of radiation exposure at the genetic level make it possible to distinguish the group of radiation protective agents having their own specific features in the implementation of their beneficial effects. The mechanism of the radioprotective action of bioflavonoids is worthy of a detailed analysis in view of their great biological importance. Radiobiological studies show that antioxidants can reduce the radiation damage to membranes and favor more adequate energy dependent adaptive and reparative processes after the exposure to radiation. Bioflavonoids are significant component of “biological protection” for a enhance of resistance of the body to environmental factors that are adverse for human health, including ionizing radiation, with reducing the risk of carcinogenic effects and decreasing the biological age. The best practical value of bioflavonoids, can be considered as the agents for prophylaxis against the development of oxidative stress. These are the reasons why the administration of natural antioxidants have a pathogenetic justification for exposures to chronic (months, years) low-rate-dose ionizing radiation. These agents were previously and are currently being developed for use during long-term, low-ratedose exposures to radiation, under conditions of long space missions. Acting as low-dose stressors through a hormetic mechanism and a “substrate” support of adaptive shifts radiomodulators results in an increase in the antioxidant defense of the body and the rearrangement of its functioning in the new environment with the modulation of gene expression of antioxidant response elements by activation of Nrd2/KeapI and Sirtuin/FoxO pathways and a decrease in the transcription factor NF-κB.

肿瘤放射治疗的发展

恶性肿瘤是目前人类死亡的主要原因之一,以美国为代表的发达国家中,超过半数的肿瘤患者在治疗过程中需要单独或联合使用放射治疗。过去的半个世纪以来,放射治疗围绕着“增效减毒”的原则展开技术迭代,不断和手术、化疗以及新兴的免疫疗法等其他手段相结合,极大地提高了治疗疗效和可及性。21世纪以来,通过采用更先进的剂量递送方式、结合实时影像的自适应规划、引入人工智能和新的粒子辐射类型等先进技术,放射治疗的安全性和有效性都得到了提高。本文回顾了近几十年来放射治疗领域的技术进步,展示了在加速器平台上进行高剂量率放射治疗研究的典型案例,总结了放射治疗相关的新兴研究热点,并对该领域的发展方向做出了展望。

踝关节骨折的低剂量螺旋CT影像检查效果

目的 探讨踝关节骨折的低剂量螺旋CT影像检查效果。方法 研究中60例踝关节骨折患者均在2020年1月—2023年7月随机抽选自我院;临床对所有踝关节骨折患者合理展开常规剂量螺旋CT扫描操作以及低剂量螺旋CT扫描操作,对两种方法的辐射剂量、诊断符合率、客观性图像质量指标以及图像清晰度分级展开比较。结果 与常规剂量CT诊断剂量长度乘积(DLP)以及CT容积剂量指数(CTDIvol)展开比较,低剂量CT测定结果均更低(均P <0.05);低剂量CT与常规剂量CT对于总诊断符合率、CT值、噪声值(SD)、图像信噪比(SNR)以及图像清晰度展开比较,结果均未呈现出统计学差异(P> 0.05)。结论 临床对踝关节骨折患者在实施CT诊断期间,发现低剂量CT以及常规剂量CT的诊断效果均较为明显,对于踝关节的损伤位置均可以明确诊断,但低剂量螺旋CT扫描运用,可将辐射剂量显著降低,所以安全性更高。

低剂量胸部CT检查对胸部肿瘤性病变的检出和诊断效果评价

目的探讨低剂量胸部CT检查对胸部肿瘤性病变的检出率和诊断价值。方法选取2000例胸部肿瘤患者随机均分为A、B两组,A组1000例使用常规剂量胸部CT扫描,B组1000例使用低剂量胸部CT扫描。结合患者的临床和影像学资料,对照评价低剂量胸部CT检查的图像质量、疾病检出率和良恶性肺结节诊断的准确率。结果与常规剂量相比,低剂量胸部CT检查总辐射剂量降低了60.23%。主观图像质量:纵隔窗质量略有下降,差异有统计学意义(P=0.001),肺窗和骨窗的图像质量差异无统计学意义(P=0.753和0.501);疾病检出率:对肺部小结节,胸腺结节、甲状腺结节、淋巴瘤、胸壁肿物、肾脏和肾上腺结节的检出率差异无统计学意义(P=0.294、0.743、0.530、0.616、0.459、0.339和0.125);对肺部小结节中癌前病变、早期肺癌的诊断准确率差异无统计学意义(P=0.345和0.648);对胸部良性病变和未定性病变诊断比较差异有统计学意义(P=0.001和*0.037)。结论低剂量胸部CT检查辐射剂量较常规CT检查大幅度降低,图像质量可以满足诊断要求,对多种胸部肿瘤性疾病的检出率及肺结节的良恶性诊断差异无统计学意义,但对部分良性和未定性病变的诊断准确率略有不足。

50~120kV脉冲X射线参考辐射场建立及剂量率测量

为满足国内医疗、安检等脉冲辐射场所对剂量监测仪表准确溯源的需求,基于栅控技术建立满足规范和标准要求的50~120 kV毫秒级脉冲X射线参考辐射场,其脉冲宽度在1~6 300 ms范围内可调。通过对该辐射场的管电压稳定性、剂量线性、重复性、脉冲波形等关键参数进行研究测试,建立脉冲X射线参考波形,并使用30 cm3的圆柱电离室开展脉冲剂量率测量研究。结果表明,管电压预设60 kV时,介入法、非介入法测量管电压的相对偏差均不超过±1.5%;可输出参考波形脉冲的最小脉冲宽度为20 ms,在1 m处95%均匀辐射野直径约为5.5 cm;且N系列、RQR系列辐射质条件下的剂量率范围可分别扩展至0.002~10 mGy/s和0.03~250 mGy/s,可用于防护仪表的量值溯源。