Assessment of Organ Dose and Effective Dose from Head CT Examination in a Large Hospital in South-Southern Nigeria

The magnitude of radiation dose imparted to patients who underwent Head Computed Tomography examination in a large tertiary hospital in South-Southern Nigeria has been estimated. CT-ExPO dosimetry software was used to determine the effective and organ doses to the head region of 40 adult patients. Scanning parameters were retrieved from the CT monitor for both contrast-enhanced and non-contrast head CT examinations. The tube potential ranged from 100 kVp to 120 kVp, while the mAs ranged from 127 mAs to 202 mAs. The mean values of the volume Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) for the contrast-enhanced Head CT examination were 166.4 ± 39.6 mGy and 3568.6 ± 756.1 mGy·cm, respectively, while for the non-contrast examination they were 86.6 ± 30.4 mGy and 2102.3 ± 870.3 mGy·cm, respectively. The effective doses were higher for the contrast-enhanced study than for the non-contrast study by a factor of 1.6. Results were compared with the European Union reference doses and other published data and were found to be higher. Doses to the organs which comprise of brain, red bone marrow, thyroid and eye lens were also estimated. The high variation in the doses in this study may be due to differences in imaging protocols such as large range of mAs and scan lengths and also the algorithm of the scanner.

Assessment of Organ Dose by Direct and Indirect Measurements for a Wide Bore X-Ray Computed Tomography Unit That Used in Radiotherapy

The aim of this study was to investigate the organ doses of patients undergoing computed tomography (CT) examination using the wide bore General Electric (GE) “Light Speed RT” unit. The head, chest and pelvic regions of the Rando-phantom were scanned with 120 kV, 200 mA, and 2.5 mm slice thickness for helical and axial modes. Thermoluminescent Dosimeter (TLD) pairs were used for the dosimetry of 10 organs. TL-counts were converted to dose by using CTDIcenter dose on CT-phantom. For the calculation of the organ doses, the ImPACT software was utilized by entering CTDIair (100 mAs) in small and large field of view (26.43 and 21.17 mGy respectively). The in-field dose ranges in helical and axial modes were 64.3 - 38 mGy and 47.6 - 19.7 mGy in head, 48.3 - 14.1 mGy and 34.1 - 10 mGy in chest, 28.4 - 10.2 mGy and 21 - 8.5 mGy in pelvic, respectively. The organ doses from software and TLD were compared and tailored as the in-field and the out-field radiation. First results showed that the organ dose was relatively higher in the helical mode on both direct and indirect measurement. The in-field organ dose differences between TLD and software were seen. In helical and axial modes, the dose differences ranged from +1 to +13.3 and -8.3 to +9.6 mGy for head exam, +1.1 to +15.3 and +0.3 to +9.1 mGy for chest, and -21.7 to +1.9 and -15.5 to +1.8 mGy for pelvic. The availability of this program for organ dose calculations by measuring CTDIair value for CT device used in the radiotherapy would be considered valuable.

The Impact of Variation in Bladder Volume on the Doses of Target and Organ-at-Risk in Intensity-Modulated Radiation Therapy for Localized Prostate Cancer

Intensity-modulated radiation therapy (IMRT) has become the mainstay of treatment for localized prostate cancer. In IMRT, minimizing differences between the conditions used during planning CT and daily treatment is important to prevent adverse events in normal tissues. In the present study, we evaluated the impact of variation in bladder volume on the doses to various organs. A total of 35 patients underwent definitive radiotherapy at Saitama Medical Center. A Light Speed RT16 (GE Healthcare) was used for planning and to obtain examination CT images. Such images were acquired after 4 - 6 days of planning CT image acquisition. The IMRT plans were optimized using the planning CT data to satisfy the dose constraints set by our in-house protocols for the PTV and the OARs. The dose distributions were then re-calculated using the same IMRT beams, and checked on examination CT images. It was clear that bladder volume affected the doses to certain organs. We focused on the prostate, bladder, rectum, small bowel, and large bowel. Regression coefficients were calculated for variables that correlated strongly with bladder volume (p < 0.05). We found that variation in bladder volume [cm3] predicted deviations in the bladder V70Gy, V50Gy, and V30Gy [%];the maximum dose to the small bowel [cGy];and the maximum dose to the large bowel [cGy]. The regression coefficients were -0.065, -0.125, -0.180, -10.22, and -9.831, respectively. We evaluated the impacts of such variation on organ doses. These may be helpful when checking a patient’s bladder volume before daily IMRT for localized prostate cancer.

Organ at Risk Doses during High Dose Rate Intracavitary Brachytherapy for Cervical Cancer: A Dosimetric Study

Background: Treatment of Cervical cancer includes a combination of external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT). ICBT helps to boost radiation dose to primary disease. Organs like rectum, bladder, sigmoid and small bowel lie close to the cervix region and these organs receive dose from EBRT as well as ICBT and we want to know the dose to these organ at risk (OAR). Materials & Methods: Dosimetric details of 174 ICBT applications done in 58 patients were retrospectively analysed. All patients received EBRT dose of 50.4 Gy in 28 fractions. All patients had ICBT, three sessions with 7 Gy prescribed to point A. Dosimetric data including dose to right and left point A and dose to OARs were recorded from Oncentra Planning System. Results: Mean dose to point A on right side was 6.89 Gy and left side was 6.91 Gy. Mean D2cc dose to rectum, bladder, sigmoid and small bowel was 3.5 Gy, 5.25 Gy, 4.75 Gy and 4.2 Gy respectively. Mean EQD2 dose combining EBRT and ICBT in point A was 78.7 Gy on right side and 79 Gy on left side. Mean EQD2 doses to D2cc of rectum, bladder, sigmoid and small bowel was 62 Gy, 74.4 Gy, 70.5 Gy and 66.5 Gy respectively. Conclusion: From the results of this dosimetric study it is evident that OARs like rectum, sigmoid, bladder & bowel are receiving only acceptable doses of radiation using point A prescribed CT based ICBT planning. Hence with regards to OAR doses, CT based ICBT planning with dose prescribed to point A is a feasible option.

容积旋转调强与调强放疗在宫颈癌放疗中的应用及剂量学、安全性研究

目的:探究容积旋转调强放疗(VMAT)与调强放疗(IMRT)在宫颈癌根治术后放疗中的应用及剂量学、安全性。方法:选取宫颈癌根治后且拟行放疗的患者60例,根据随机数字表法将其分为VMAT组(30例)和IMRT组(30例),分别给予VMAT治疗与IMRT治疗,对比两组机器跳数、治疗计划执行时间、靶区适形度(CI)和均匀性指数(HI)、危及器官的剂量差异及不良反应等。结果:VMAT组在计划控制点多于IMRT组的情况下,其治疗时间仍短于IMRT组。通过Delta验证,VAMT组患者的3%/3 mm和4%/4 mmγ通过率低于IMRT组(均P<0.05)。VAMT组计划的CI记录与IMRT组比较无统计学差异(P>0.05),但与IMRT组相比,VAMT组的HI更接近于1,差异有统计学意义(P<0.05)。VAMT组直肠的V_(30)、V_(40)、V_(50)低于IMRT组,VAMT组对骨盆、膀胱的V_(20)、V_(30)、V_(40)低于IMRT组(均P<0.05);VAMT组和IMRT组发生胃肠道反应患者分别有9例(30.00%)、14例(46.67%);VAMT组和IMRT组发生膀胱反应的患者分别有3例(10.00%)、5例(16.67%),两组胃肠道、膀胱反应发生率比较均无统计学差异(均P>0.05)。两组疗效及随访期内复发或转移情况对比均无统计学差异(均P>0.05)。结论:在宫颈癌根治术后放疗时,VMAT治疗可时间缩短,且治疗效率及剂量学参数优于IMRT,可有效保护骨盆、直肠和膀胱,安全性好。

眼部CT扫描应用器官剂量调制技术的可行性研究

目的:研究器官剂量调制技术在眼部CT扫描中应用的可行性和价值。方法:选取2021年8月至2023年8月首都医科大学附属北京友谊医院收治的330例行眼部CT检查患者,根据扫描时所采用的管电流控制方式将其分为调制组、常规剂量组和低剂量组,调制组采用器官剂量调制技术,智能自动管电流70~150 mA;常规剂量组采用固定管电流100 mA;低剂量组采用固定管电流70 mA。比较3组辐射剂量及CT成像质量差异。结果:调制组行横断扫描的剂量长度乘积(DLP)、容积CT剂量指数(CTDI_(vol))和有效剂量(ED)分别为62.37、12.83和0.143 mSv,显著低于常规剂量组的115.23、18.93.和0.265 mSv,两组比较差异均有统计学意义(F=2544.944、6009.596、2544.944,P<0.05);行冠状扫描,调制组DLP、CTDI_(vol)及ED分别为68.19、13.15和0.156 mSv,显著低于常规剂量组的122.41、19.20和0.282 mSv,两组比较差异有统计学意义(F=1232.413、3813.940、1232.413,P<0.05)。行横断扫描,调制组、常规剂量组和低剂量组图像质量优良率分别为98.83%、86.15%和47.69%,3组比较差异有统计学意义(x^(2)=53.908,P<0.05);行冠状扫描,调制组、常规剂量组和低剂量组图像质量优良率分别为96.61%、80.70%和48.28%,3组比较差异有统计学意义(x^(2)=20.992,P<0.05)。结论:眼部CT扫描应用器官剂量调制技术,行横断扫描、冠状扫描时,均可在确保成像质量符合诊断需要的前提下,显著降低患者接受辐射剂量,在临床上具有较高的应用可行性和应用价值。

冬虫夏草及其近缘品中铅、镉、砷污染评价及人体健康累积风险评估方法探索

目的:对冬虫夏草及其近缘品中铅(Pb)、镉(Cd)、砷(As)的残留量进行测定,探索符合冬虫夏草及相关产品使用特点的污染评价及人体健康风险评估方法。方法:基于冬虫夏草及其近缘品中Pb、Cd、As的残留量监测数据,综合运用单因子污染指数法、尼梅罗综合指数法、金属污染指数法对冬虫夏草及其近缘品进行重金属污染评价,计算重金属日暴露量,分别采用危害指数法和更加精确的靶器官毒性剂量法对Pb、Cd、As联合暴露产生的健康风险进行累积风险评估。结果:污染评价结果说明,冬虫夏草及其近缘品中As的污染应引起关注,不同品种污染程度为冬虫夏草(繁育品)=蛹虫草<冬虫夏草(野生品)<香棒虫草<亚香棒虫草;人体健康风险评估结果表明,对于心血管和神经系统,1批冬虫夏草(野生品)全草中Pb、Cd、As联合暴露产生的累积健康风险需被进一步关注。结论:冬虫夏草及其近缘品重金属污染评价,以及人体健康风险评估方法,可为中药安全性评价及相关限量标准的制修订提供参考。

冶炼厂周边农用地土壤重金属非致癌健康风险评估及修正

为科学量化重金属复合暴露产生的非致癌健康风险,引入靶器官毒性剂量(TTD)模型和证据权重分析模型(WOE)对传统评估模型(HRA)的非致癌健康风险进行修正,并以华中某冶炼厂周边农用地土壤重金属为例,探究3种模型对非致癌健康风险评估结果的影响。结果表明:土壤重金属镉(Cd)、铅(Pb)、铬(Cr)和砷(As)的浓度均值分别为0.37、36.65、69.06和7.66mg/kg,其中Cd、Pb和Cr不同程度超出研究区土壤背景值,4种重金属传统非致癌健康风险值(HI_(HRA))为2.27×10^(-3)~3.35×10^(-1)。经TTD模型和WOE模型修正后4种重金属HI_(TTD)和HI_(WOE)分别为1.64×10^(-2)~5.50×10^(-1)和1.08×10^(-2)~6.09×10^(-1),其中HI_(TTD)、HI_(WOE)均值分别为HI_(HRA)均值的1.88倍和1.17倍。研究显示,对多种重金属复合污染的农用地开展人体非致癌健康风险评估时,需考虑多靶器官效应及重金属间的交互作用,避免传统风险评估方法低估或高估土壤污染对暴露人群产生的实际健康损害。

基于辐射光致发光的高剂量测量材料应用研究进展

近年来,研究发现若干用于辐射探测的辐射光致发光材料因其可测量剂量限值高及剂量范围宽,已被广泛应用于核退役设施剂量监控、荧光核径迹探测、医学治疗、辐射成像及核辐射场所可视化等领域。本研究针对目前可用于高剂量测量的辐射光致发光材料(包括无机激活剂离子掺杂体系、无机未掺杂体系及有机聚合物体系)的研究现状进行概述,重点对各体系的发光机理、基本特征、种类及应用现状进行梳理,同时对比分析不同体系材料辐射剂量响应高低的影响因素及其性能优劣。本研究旨在对目前适用于高剂量测量的辐射光致发光材料在剂量探测性能提升方面的研究进行概述,同时提出改进优化的可行性举措,并对其未来发展趋势进行展望。

核电厂流出物中^(14)C在海产品中的浓集研究及公众剂量评价应用

滨海核电厂流出物的排放会对周围公众产生照射,其中剂量贡献最大的放射性核素为^(14)C,又以食入海产品中^(14)C所致的剂量占比最高。在进行食入海产品这一关键途径的剂量评价时,海产品中^(14)C的浓集情况将直接影响剂量评价的合理性。本文采用比活度平衡模式,充分考虑福清核电厂址海域海水及海产品实际碳含量,计算出不同种类海产品^(14)C浓集因子,并通过与部分厂址海产品的^(14)C浓集因子实测值及国际原子能机构(IAEA)推荐值对比验证,得到了适用于福清核电厂址海域的海产品^(14)C浓集因子,推荐鱼类取6800、藻类取5300、甲壳类取5000、软体动物取4500,并应用于公众剂量评价,划分不同年龄组,计算出食入海产品中^(14)C所致的公众个人有效剂量。

金属有机框架材料(MOFs)的电子束辐射稳定性

本研究在不同气氛(空气、氮气)、分散液(水、甲醇、乙醇)以及不同剂量条件下对4种典型的金属有机框架材料(MOFs)(MIL-101(Cr)、ZIF-8、UiO-66和UiO-66-NH2)进行了电子束辐照处理。通过傅里叶变换红外光谱、X射线衍射谱和扫描电子显微镜等方法对MOFs材料在辐照前后的化学组成、晶体结构和表面形貌进行表征。结果表明,上述4种MOFs材料在高于5000 kGy的剂量辐照后,其相应的红外特征峰、衍射峰和表面形貌特征均未产生显著变化,表现出了良好的辐射稳定性。这为MOFs材料在辐射环境下的进一步应用提供了研究基础。

乳腺癌术后放疗治疗技术在危及器官防护效果中的应用

放射治疗是乳腺癌综合治疗的重要方式。乳腺癌术后放疗可降低复发率、提高长期生存率,但也不可避免地造成对危及器官的照射。这些照射降低了器官功能或增加相关疾病患病风险,且随着患者生存期延长更加凸显,已成为影响患者长期生存的主要因素。因此,保护好乳腺癌放疗患者的危及器官,对其生存质量有着重要的意义。近年来,放疗设备及各项技术飞速发展,治疗的方式不断更新,精度、高效、安全性的治疗技术在保护危及器官中不断发挥作用。本文对降低乳腺癌放疗患者危及器官剂量的技术及相关措施进行综述,以期为提高乳腺癌治疗和危及器官防护效果提供参考。

突击剂量碘解磷定联合血液灌流治疗ICU有机磷农药中毒患者的效果

目的:探析ICU有机磷农药中毒患者采用突击剂量碘解磷定联合血液灌流治疗的临床效果。方法:选择2021年1月—2022年12月潜江市中心医院重症医学科收治的96例有机磷农药中毒患者,采用随机数字表法分为研究组、对照组,各48例。对照组给予常规剂量碘解磷定联合血液灌流治疗,研究组给予突击剂量碘解磷定联合血液灌流治疗。比较两组临床总有效率、格拉斯哥昏迷量表(GCS)评分、胆碱酯酶(ChE)水平、ChE复常时间、阿托品化时间、昏迷时间、住院时间、不良反应发生率。结果:研究组临床总有效率高于对照组,差异有统计学意义(P<0.05)。治疗后,研究组GCS评分、ChE水平均高于对照组,差异均有统计学意义(P<0.05);研究组ChE复常时间、阿托品化时间、昏迷时间、住院时间均短于对照组,差异均有统计学意义(P<0.05)。两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论:ICU有机磷农药中毒患者采用突击剂量碘解磷定联合血液灌流治疗效果显著,可改善昏迷状态,提升ChE水平,缩短ChE复常时间、阿托品化时间,加速苏醒,缩短住院时间,治疗安全性较高。

VirtualDose：一个新的计算CT扫描所致器官剂量的软件工具更多〉〉相关学者白玫朱国英章伟敏魏岚刘彬费晓璐彭志刚马晓晖肖德涛熊小兵相关检索词防护 护士最优化 螺旋应用软件 人体模型辐射防护 职业暴露辐射剂量 计算软件tomography 有效剂量前提 遗传算法器官 快速计算x-ray computed 体素职业危害 radiation dosage

随着多排螺旋CT的广泛应用，CT扫描所产生的辐射风险已引起广泛关注。准确评价CT扫描所致受检者的辐射剂量，是尽可能降低CT辐射风险、实现辐射防护最优化的前提。VirtualDose是一款可以准确快速计算CT扫描所致受检者器官剂量与有效剂量的应用软件。VirtualDose拥有基于25种体素化人体模型计算结果的庞大器官剂量数据库，与现有的其他CT剂量计算软件相比，计算结果更为准确。

Evaluation of X-Ray Doses on Children, from Paediatric Hospitals in Sudan

Children are more sensitive to radiation than adults, so radiation protection in paediatric radiology deserves special attention. This work estimates the effective doses and body organ doses due to chest examinations in infants and paediatrics. Two examination incidences, AP and PA for chest X-ray exposures were evaluated and compared with respect to the radiographic technique employed. This study was carried out in three paediatric hospitals in Sudan. The age intervals considered were 0 - 1 year, 1 - 5 years, 5 - 10 years and 10 - 15 years. The results obtained for organ doses and effective doses were calculated using a software package developed by the Radiological Protection Centre of the Saint George’s Hospital, London. Effective dose values were also evaluated considering weight intervals from 1 - 10 kg, 10 - 20 kg, 20 - 30 kg and 30 - 40 kg. Large discrepancies were encountered between the three hospitals, probably due to the different radiographic technique employed, calibration and maintenance of the X-ray equipment, technicians’ expertise, processing conditions.

Will High Dose Rate Interstitial Brachytherapy Be a Surrogate to Surgery in Early Mobile Squamous Cell Carcinoma of Tongue—An Indian Experience

The study was intended to highlight functional outcome and survival advantage when High Dose Rate (HDR) interstitial implant was used for anterior 2/3rd tongue, either as a primary or as boost depending upon stage of disease. Materials and Methods: Fifty-one patients with squamous cell carcinoma of anterior 2/3rd tongue received interstitial brachytherapy either as primary or as boost with Iridium 192 remote after loading high dose rate (Microselectron or Gamma MediX) machines from November 2008 to September 2013. Age group ranged from 32 to 73 years, mean 52.1. Of these 51, 37 were males and 14 were females. 8 patients belonged to Stage I, 18 from Stage II and 28 patients were Stage III. Stage I patients received primary brachytherapy alone of dose 38.50 Gy to 40 Gy and fraction dose ranged from 250 cGy to 350 cGy. Stage II and Stage III patients received external beam radiation of dose 44 Gy/200cGy per fraction for 22 fractions followed by spinal cord sparing for 6 Gy/200cGy per fraction for 3 fractions. Brachytherapy boost of dose 21 Gy was delivered after external beam radiation. Stage III patients received concurrent chemotherapy with Injection Cisplatin along with external beam radiotherapy 44 Gy/200cGy per fraction for 22 fractions followed by spinal cord sparing for 6 Gy/200cGy per fraction for 3 fractions. Brachytherapy boost of dose 21 Gy was delivered after external beam radiation. 55% of patients were habituated to tobacco and alcohol in one form or the other or both. Surprisingly 45% of patients were nonsmokers and non-alcoholic. Results: Follow-up period ranged from eight months to sixty months. 42 patients had complete response. 9 patients had residual disease. 2 patients died due to non-cancerous cause though they had excellent local control, one with pulmonary tuberculosis and the other with massive Myocardial Infarction. 2 patients died due to disease progression. Overall complete response rate was 82.35%. Those patients who had good coverage index and conformal index had good response compared to those patients with lesser these values. Conclusion: It is surprising to observe from the study that oral cavity cancers are not uncommon in non-smokers and non-alcoholics. Overall complete response of 82% is comparable to any other study quoted in literature. Surgery offers same cure rate but at the rate of organ loss and functional impairment. Organ preservation with good functional outcome is possible in radiotherapy unlike surgery. This study proves brachytherapy can be considered as a surrogate to surgery in early stage tongue cancers with good functional outcome and with lesser morbidity.

Impact of human motion on TVOCs inhalation dose under side re-circulated ventilation

The main objectives were to (1) calculate the total volatile organic compounds (TVOCs) inhalation dose, (2) analyze the proportions of human’s inhaled contaminant dose from different sources, and (3) present a newly defined ratio of relative inhalation dose level (RIDL) to assess indoor air quality (IAQ). A user defined function based on CFD (computational fluid dynamics) was developed, which integrated human motion model with TVOCs emission model in a high sidewall air supply ventilation mode. Based on simulation results of 10 cases, it is shown that the spatial concentration distribution of TVOCs is affected by human motion. TVOCs diffusion characteristic of building material is the most effective way to impact the TVOCs inhalation dose. From the RIDL index, case A-2 has the most serious IAQ problem, while case D-1 is of the best IAQ.

有机酸对果酒品质的影响及调控技术研究进展

酒石酸、苹果酸、柠檬酸、乳酸、琥珀酸等有机酸是果酒中重要的呈味物质,对果酒品质有着重要影响。有机酸的组成和含量变化决定了果酒的酸度和pH,且可能与果酒基质成分之间发生相互作用,影响果酒的感官品质和稳定性。本文围绕果酒中主要有机酸的组成、含量及其与果酒品质的量效关系展开综述,系统阐明了其在果酒发酵及陈酿过程中对口感、颜色、香气以及稳定性等方面的影响及机制,并介绍了果酒有机酸的调控技术和工艺,对有机酸改善果酒品质的未来发展方向作出展望,以期为果酒感官品质的进一步提升提供理论参考。

近10年针刺麻醉研究进展

针刺麻醉是一种新型的麻醉手段,于20世纪50年代开始应用于临床。通过检索近10年来国内有关针刺麻醉的文献,论述针刺麻醉的临床应用及腧穴配伍。针刺麻醉的临床应用体现在可以减少麻醉剂使用量、减轻手术疼痛、降低术后不良反应、保护脏器功能、调整围手术期免疫功能等方面。总结针刺麻醉的常用腧穴,对不同手术部位的取穴进行分析。归纳针刺麻醉目前存在的局限性,并提出针刺麻醉研究未来发展的4点建议。

急性摄入^(131)I的医学应急参考可测量推导

通过推导与甲状腺待积器官剂量相关的^(131)I可测量,为^(131)I生产单位职业卫生管理和制定相关作业的医学应急计划提供参考。依据我国《职业性放射性甲状腺疾病诊断》规定的甲状腺待积器官剂量以及《国际辐射防护和辐射源基本安全标准》为避免严重确定性效应和降低随机性效应而推荐的防护行动水平,推算单次吸入达到相应的甲状腺待积器官剂量时的实用量,包括工作场所浓度、甲状腺^(131)I含量和尿碘日排量。当人员(不考虑个体防护)停留的工作场所^(131)I化合物和^(131)I蒸气浓度CA分别达2.1×10^(4)Bq/m^(3)和1.2×10^(4)Bq/m^(3),或甲状腺^(131)I含量M(t)甲达3.8×10^(4)Bq,或尿^(131)I日排量M(t)尿达4.5×10^(1)Bq时,应该根据防护目的,结合职业人员接触时间、体力劳动强度或者监测与摄入的间隔时间、^(131)I的理化形态等,采取立即体检、会诊、指示性医疗、促排、阻吸收、健康监护等行动。以上可测量对于^(131)I生产单位职业卫生管理以及事故应急的后果预测和医学干预等.具有直接的指导意义。