心血管介入手术中透视时间作为辐射剂量警示指标的可行性研究

目的以心血管介入术后采集空气比释动能(reference air kerma,AK)值和剂量面积乘积(dose-area product,DAP)值数据为依据,分析术中透视时间报警设置作为心血管介入手术辐射剂量的监测和警示工具的可行性。方法回顾性分析2016年11月至2018年1月上海长海医院736例冠状动脉造影术(CAG)和经皮冠状动脉治疗术(PCI)病例,收集术中透视时间、AK和DAP数据资料。德国西门子成像设备分组(Ceiling系统和Biplane系统)和手术类型分组(CAG和PCI),对辐射剂量数据进行比较,以及对心血管介入手术AK和DAP值与透视时间数据采用Spearman检验解析相关性。结果Ceiling和Biplane成像系统中手术透视时间为(8.9±7.8)和(8.6±7.3)min,透视AK均值和DAP均值分别为(472±474)、(510±509)mGy、(4548±4085)和(4255±3781)μGy·m^2,术中总(透视+造影)AK和DAP均值为(703±595)、(733±614)mGy、(6253±4938)和(5681±4432)μGy·m^2。CAG与PCI术中透视时间均值分别为(2.4±0.9)和(15.7±4.9)min。PCI透视辐射剂量(AK和DAP)与术中总辐射剂量比值分别为74%和78%。心血管介入手术中透视时间与AK值(r=0.822)和DAP值(r=0.844)都呈高度相关性(P<0.001)。结论透视采集辐射剂量是心血管介入手术中辐射剂量的主要来源,辐射剂量随透视时间延长而增加,透视时间监测和报警设置在心血管介入临床应用中作为术中辐射防护工具有一定的参考和警示价值。     

心血管病介入操作时患者受照剂量研究

目的 对心血管介入手术中患者所受辐射剂量及与辐射剂量相关的指标进行采集和分析,为改善患者的辐射防护提供依据.方法 对在省属三级甲等医院进行的26例完整的心血管介入手术的患者进行临床数据采集,按手术类别分成冠状动脉血管造影术(CA)及行冠状动脉血管造影术(CA)后继续行经皮穿刺腔内冠状动脉成形术(PTCA)两组,采用TLD个人剂量计照射野矩阵测量法,检测患者荧光照射时间、入射皮肤剂量(ESD)、最高皮肤剂量(PSD)、剂量-面积乘积(DAP)等指标,用TLD测量在模拟心血管手术条件下体模器官剂量.结果 荧光透视时间为(17.7±15.6)min,范围为0.80～42.4 min;ESD范围为(159±138)mGy,4.40～459 mGy;PSD范围为(769±705)mGy,22.6～2.43×103mGy.CA+PTCA组的荧光照射时间、ESD、PSD均大于CA组,差异有统计学意义.最大皮肤受照剂量与透视时间有较好的相关性(r=0.84,P＜0.01).结论 心血管病放射性介入操作时,可通过透视时间来估算最大皮肤受照剂量.

Abstract：

Objective To collect and analyze the radiation dose to patients in cardiovascular interventional procedures and the radiation dose-related indicators,in order to provide a basis for improving radiation protection of patients.MethodsThe clinical data of 26 cases of complete cardiovascular interventional procedures was collected in the municipal Grade A Class Three hospitals,including coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA),and the patient-received radiation doses and other related factors was studied.TLD personal dosimeter radiation field matrix method was used to measure fluorescence time,the entrance skin dose (ESD),the peak skin dose (PSD),dosearea product (DAP) and other indicators.TLD was used to measure the organ dose of the phantom under the cardiovascular interventional procedure condition.ResultsThe fluoroscopy time was (17.7 ±15.6) min during the range of 0.80-42.4 min.The average entrance skin dose (ESD) was (159 ± 138)mGy during the range of 4.40-459 mGy.The peak skin dose (PSD) was (769 ± 705) mGy during the range of 22.6 - 2.43 × 103mGy.The fluorescence time,entrance skin dose (ESD) ,peak skin dose (PSD) of the group CA + PTCA are greater than the group CA and the difference has statistical significan.The peak skin dose and the fluoroscopy time have good linear correlation (r = 0.84,P ＜ 0.01 ).Conclusion The peak skin dose the patient received in cardiovascular interventional radiological operation can be estimated through the fluoroscopy time.     

不同类型心血管介入手术辐射剂量分析

目的 分析不同类型心血管介入手术患者所受X射线辐射剂量以及影响辐射剂量的因素.方法 按照甲、乙、丙3位术者的患者资料,抽取本院接受心血管介入手术的患者442例,包括单行冠状动脉造影术(CAG)、冠状动脉介入术(PCI)、射频消融术(RFCA)、先天性心脏病介入术(CHD)和永久性心脏起搏器植入术(PCPI).采集患者的皮肤表面累积入射剂量(CD)、剂量面积乘积(DAP)、透视时间.结果 CAG、PCI、RFCA、CHD、PCPI各组患者的CD值分别为(0.34 ±0.23)、(1.33±0.76)、(0.71±0.43)、(0.27±0.22)和(0.92±0.42) Gy,DAP值分别为(34.18±23.33)、( 135.92±81.14)、( 79.79±50.66)、(27.93±23.66)和(94.60±48.11) Gy.cm2.透视时间分别为(4.82±3.73)、(16.64±9.01)、(17.04±15.29)、(9.60±5.97)和(7.31±6.45) min.DAP值与透视时间呈高度相关性(r =0.84,P＜0.05).结论 不同类型心血管介入手术患者所受的平均辐射剂量不同.辐射剂量和透视时间与手术难易度和术者操作熟练程度有关,可通过提高操作技术水平、减少透视时间降低患者辐射剂量.     

先心病患者在介入诊疗中辐射剂量控制分析

【摘要】 目的 探讨如何控制先心病（CHD）患者在介入诊疗中辐射剂量。方法 利用SIEMENS DSA设备连续观察介入诊疗的CHD患者273例。按年龄和疾病分组统计总辐射时间（T）、累积剂量（CD）、剂量面积乘积（DAP）、峰值皮肤剂量（PSD）和有效剂量（ED）,分段统计CD和PSD,结合CHD介入诊疗实际进行分析,为控制辐射剂量提供依据。结果 总体T、CD、PSD（1/2CD）、PSD（4/5CD）、DAP、ED中位数达到3.05 min、113 mGy、56.5 mGy、90.4 mGy、11.62 Gy?cm2,、1.98 mSv,参数范围差异显著;CHD介入诊疗以未成年为主分布于各年龄段、各病种,年龄分组以少年中位数突出,疾病分组以室内隔缺损（VSD）中位数较大,各分组参数范围均差异显著;辐射剂量分段统计以＜100 mGy为主,＞500 mGy较少。结论 提高术者及介入放射技师辐射剂量控制意识及技能,采用多种措施减少或避免辐射暴露,通过数据库建立辐射剂量参照值,有助于控制CHD患者介入诊疗辐射剂量。     

用胶片法对心脏介入程序中患者峰值皮肤剂量测量研究

目的 采用胶片法对进行心血管介入手术中患者所受峰值皮肤剂量（PSD）进行测量研究,包括冠状动脉血管造影术（CA）和经皮穿刺腔内冠状动脉成形术（PTCA）。方法 选用Gafchromic XR-RV3胶片在两家医院进行患者峰值皮肤剂量的测量。手术时将胶片放在患者身下的诊视床上。记录手术中监视器上显示的kV、mA、透视时间、剂量面积乘积（DAP）、参考点累积剂量等相关信息。采用Epson V750平板扫描仪对胶片进行分析扫描及分析,选用FilmQA软件分别测量图像的红、绿、蓝三色通道的像素值,使用红通道数据计算患者的 PSD。对PSD与设备显示参数进行相关分析,对相关的变量进行多元线性回归分析。结果 共测量CA手术26例,CA+PTCA手术19例。CA手术中,透视时间最高为17.62 min,累积剂量和DAP最大分别为1 498.50 mGy和109.68 Gy ·cm²,PSD最大为361.20 mGy。CA+PTCA手术中,曝光时间最长为64.48 min,累积剂量和DAP最大分别为6 976.20 mGy和5 336.00 Gy ·cm²,17例患者的PSD在1 Gy以内,1例患者PSD在1~2 Gy之间,1例患者PSD超出了发生皮肤损伤2 Gy的阈值,达到了2 195.70 mGy。CA程序中,患者PSD与DAP相关（R²=0.815,P<0.05）,CA+PTCA程序中,患者PSD与累积剂量相关（R²=0.916,P<0.05）。结论 心脏介入放射学程序中部分患者的PSD会超出ICRP建议的发生皮肤确定性效应的2 Gy阈值。DSA设备上显示的剂量相关的参数,只能粗略估算患者PSD的大小。使用XR-RV3胶片精确测量介入手术中患者的峰值皮肤剂量是一种非常快捷、有效的方法。     

心血管疾病患者在介入诊疗过程中辐射剂量分析

目的 分析心血管疾病患者在介入诊疗过程中的辐射剂量,探讨其预防措施.方法 抽取用SIEMENS Aritis Zee Floor DSA介入诊疗的心血管疾病患者186例,记录随机配备的辐射检测系统显示的总辐射时间(T)、剂量面积乘积(DAP)、累积剂量(CD),由DAP估算有效剂量(ED),由CD估算最高皮肤剂量值(PSD).结果 患者所受T为0.9～71.2 min,平均10.5 min,＞30 min的9例(4.8％);ED为0.11～282.9 mSv,平均32.2 mSv,＞100 mSv的10例(5.4％);1 Gy＜PSD (1/2CD)≤3Gy的40例(21.5％),PSD(1/2CD)＞3 Gy的4例(2.2％);1 Gy＜ PSD(4/5CD)≤3Gy的53例(28.5％),PSD(4/5CD)＞3Gy的14例(7.5％).T与PSD(1/2 CD)、PSD(4/5CD)、ED在置信度(双侧)为0.01时显著相关.结论 23.7％～36.0％心血管介入患者可因累积剂量导致严重的皮肤损伤,5.4％心血管介入患者有显著的致癌危险.     

子宫肌瘤患者子宫动脉栓塞过程中的X线辐射研究

目的研究子宫肌瘤患者在子宫动脉栓塞(UAE)术中所经受的X射线照射及降低辐射的方法。方法回顾性分析早期90例和近期10例UAE辐射剂量资料,采用DSA机(AngiostarPlus)配置的穿透电离室型剂量监测系统(DiamentorKI和DiamentorED),在线读取面积剂量乘积(DAP)(cGy·cm2)和入射表面剂量(ESD)(mGy)。结果早期90例UAE透视时间(28.60±23.73)min,摄影(87±38)帧,DAP均值(6178±3802)cGy·cm2,ESD均值(378±245)mGy。近期10例UAE透视时间(19.80±7.18)min,摄影(83±13)帧,DAP均值(1722±342)cGy·cm2,ESD均值(121±32)mGy。透视剂量率均值约为早期的1/2,图像采集剂量率均值约为早期的1/4。结论缩短透视时间与减少透视剂量率、减少图像采集帧数与图像采集剂量率,是降低UAE治疗过程中患者X射线辐射的有效方法。     

急性冠状动脉综合征介入患者辐射剂量分析

目的分析200例急性动脉综合征介入治疗患者受照射剂量,探讨病变部位、狭窄程度、年龄和手术医生等因素对辐射剂量的影响。方法回顾分析我院200例急性动脉综合征行介入治疗(PCI)患者所记录的剂量资料,随机配置的剂量检测系统记录剂量面积乘积(DAP)和累计剂量(CD),根据DAP值估算有效剂量(ED)。根据血管病变受累程度分为单一病变和复杂病变以及患者年龄分组(小于40岁组,40~60岁组及大于60岁组)、左右侧冠状动脉和第一操作医生对患者受辐射剂量的影响。结果①本次收录200例行PCI术者累积剂量CD值191~5524 mGy,平均值(1157±781)mGy;剂量面积乘积DAP值(12714~417228)mGy·cm^2,平均值(100690±63896)mGy.cm^2;有效剂量ED范围1.119~58.411 mSv,平均值(14±9)mSv。②单一病变相比复杂病变辐射剂量少,CD值、DAP值、ED值差异有统计学意义(P<0.05)。③左侧冠状动脉大于右侧冠状动脉(P<0.05)。④3个年龄组间各个剂量值方差分析差异无统计学意义(P>0.05)。⑤2组不同年资操作医生患者所受剂量差异无统计学意义(P>0.05)。结论急性冠状动脉综合征PCI术患者接受辐射剂量差异较大,主要与病变本身(包括病变部位和累计范围及变异等)因素相关。     

旋转造影与标准造影术患者辐射剂量比较

目的 比较双轴旋转造影（RA）与传统标准造影（SA）时患者所受辐射剂量。方法 采用同一拟人模体模拟临床条件下的冠状动脉造影。根据不同造影模式,实验分为RA组和SA组,根据不同电影时间,SA组又分为2 s组（SA1）、3 s组（SA2）、5 s组（SA3）3个亚组。造影操作使用机器预设程序自动调节造影体位并控制透视及造影时间,每组均使用同一模体重复操作10次完整造影,采用TLD 3×3矩阵和造影机随机配备的射线剂量仪同时记录辐射剂量,后者可记录剂量面积乘积（DAP）和空气比释动能（AK）,每组数据重复测量10次取均值进行比较。结果 完成整个造影操作,RA组累计DAP、AK均值分别为3 061.6 mGy·cm²和64.2 mGy,低于SA1组（4 213.9 mGy·cm²和85.5 mGy）、SA2组（6 436.0 mGy·cm²和112.2 mGy）、SA3组（12 810.4 mGy·cm²和243.7 mGy）。RA组累计皮肤入射剂量的均值（37.70 mGy）高于SA1组（26.56 mGy）,但低于SA2组（46.86 mGy）、SA3组（77.79 mGy）。SA中3个亚组TLD剂量最大点与剂量最小点差异十分显著,而RA组剂量分布相对平均。结论 双轴旋转造影与传统标准造影相比,患者的累计辐射剂量显著降低,在一定程度上避免了皮肤损伤。     

107例数字减影血管造影受检者所受辐射剂量分析

目的 统计血管造影受检者每次检查所受辐射剂量值及影响辐射剂量的相关因素,为分析、评估放射诊疗风险提供数据参考。方法 收集107例受检者检查时在线记录的全部辐射剂量值及其与剂量相关的技术参数值,按照检查区域头部、腹部和心脏进行分类,统计每例受检者的总透视时间、透视累积剂量面积乘积(DAP)、透视累积皮肤入射剂量(ESD),计算透视剂量率;统计每例受检者的造影曝光次数、造影曝光时间、采集帧频率,以及造影累积剂量面积乘积和造影累积皮肤入射剂量;统计每例受检者的透视加造影的总累积剂量面积乘积和总累积皮肤入射剂量。对所有数据分门别类进行相应的对比分析。结果 冠状动脉造影+介入,ESD为(22 285.5±18 682.7)μGy·m²,DAP为(2 942.1±2 557.3)mGy;头部血管造影DAP为(25 929.6±8 302.7)μGy ·m²,DAP为(1 288.8±682.3)mGy;腹部血管造影,DAP为(12 129.7±10 646.1)μGy·m²,ESD为(730.1±584.7)mGy。结论 血管造影受检者所受总累积剂量,冠状动脉造影相对最高,其次是头部血管造影,腹部血管造影相对较低。     

有效剂量与有效剂量当量的异同

本文作者主要讨论ＩＣＲＰ６０号出版物中提出的有效剂量，与ＩＣＲＰ２６号出版物中的有效剂量当量，在概念和使用上比较它们的异同。     

多层螺旋CT肺部低剂量与常规剂量检查的放射剂量评估

目的比较多层螺旋CT肺部低剂量与常规剂量检查的X线辐射剂量,为低剂量多层螺旋CT普查早期肺癌提供剂量参数. 资料与方法肺部低剂量与常规剂量多层螺旋CT扫描共54例.其中,低剂量扫描24例,扫描参数为:120 kV,20 mAs,准直器4×5 mm,重建层厚8 mm,床速30 mm/周,螺距为7,扫描时间0.5 s/周;常规剂量扫描30例,扫描参数为:120 kV,90 mAs,准直器4×5 mm,重建层厚8 mm,床速30 mm/周,螺距为7,扫描时间0.5 s/周.观察并计算两种扫描剂量的权重CT剂量指数(CTDIw),有效mAs,总mAs,剂量长度乘积(DLP)及有效辐射剂量. 结果肺部低剂量扫描的CTDIw为1.38 mGy,是常规剂量扫描(6.21 mGy)的22.2%;低剂量扫描的DLP为44 mGy*cm,明显低于常规剂量扫描的189 mGy*cm(P＜0.01);低剂量扫描的总mAs为459,是常规剂量扫描(1 308)的35.1%;低剂量扫描的X线最大有效辐射剂量为0.9 mSv,明显低于常规剂量扫描的4.2 mSv(P＜0.01). 结论多层螺旋CT肺部低剂量扫描(20 mAs)的有效辐射剂量为常规剂量扫描的21.4%,适用于高危人群普查早期肺癌.     

Radiation exposure to premature infants in a neonatal intensive care unit in Turkey

OBJECTIVE: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. MATERIALS AND METHODS: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESD(TO)) (n = 23) and from the use of thermoluminescent dosimetry (ESD(TLD)) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESD(TO) by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESD(TO) and ESD(TLD) were correlated using linear regression analysis. RESULTS: The mean ESD(TO) for the chest and abdomen were 67 microGy and 65 microGy per procedure, respectively. The mean ESD(TLD) per radiograph was 70 microGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 microGy) per radiograph. Mean effective doses were 16 and 27 microSv per procedure for the chest and abdomen, respectively. ESD(TLD) was well correlated with ESD(TO) obtained from the total chest and abdomen radiographs for each infant (R(2) = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 x 10(-6) to 2 x 10(-6) and 0.6 x 10(-6) to 2.9 x 10(-6) for chest and abdomen radiographs, respectively. CONCLUSION: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other.     

Size-specific dose estimates: Localizer or transverse abdominal computed tomography images?

AIM: To investigate effect of body dimensions obtained from localizer radiograph and transverse abdominal computed tomography (CT) images on Size Specific Dose Estimate.METHODS: This study was approved by Institutional Review Board and was compliant with Health Insurance Portability and Accountability Act. Fifty patients with abdominal CT examinations (58 ± 13 years, Male:Female 28:22) were included in this study. Anterior-posterior (AP) and lateral (Lat) diameters were measured at 5 cm intervals from the CT exam localizer radiograph (simple X-ray image acquired for planning the CT exam before starting the scan) and transverse CT images. Average of measured AP and Lat diameters, as well as maximum, minimum and mid location AP and Lat were measured on both image sets. In addition, off centering of patients from the gantry iso-center was calculated from the localizers. Conversion factors from American Association of Physicists in Medicine (AAPM) report 204 were obtained for AP, Lat, AP + Lat, and effective diameter (√ AP * Lat) to determine size specific dose estimate (SSDE) from the CT dose index volume (CTDI_vol) recorded from the dose reports. Data were analyzed using SPSS v19.RESULTS: Total number of 5376 measurements was done. In some patients entire body circumference was not covered on either projection radiograph or transverse CT images; hence accurate measurement of AP and Lat diameters was not possible in 11% (278/2488) of locations. Forty one patients were off-centered with mean of 1.9 ± 1.8 cm (range: 0.4-7 cm). Conversion factors for attained diameters were not listed on AAPM look-up tables in 3% (80/2488) of measurements. SSDE values were significantly different compared to CTDI_vol, ranging from 32% lower to 74% greater than CTDI_vol.CONCLUSION: There is underestimation and overestimation of dose comparing SSDE values to CTDI_vol. Localizer radiographs are associated with overestimation of patient size and therefore underestimation of SSDE.     

CT Radiation Dose Optimization and Estimation: an Update for Radiologists

In keeping with the increasing utilization of CT examinations, the greater concern about radiation hazards from examinations has been addressed. In this regard, CT radiation dose optimization has been given a great deal of attention by radiologists, referring physicians, technologists, and physicists. Dose-saving strategies are continuously evolving in terms of imaging techniques as well as dose management. Consequently, regular updates of this issue are necessary especially for radiologists who play a pivotal role in this activity. This review article will provide an update on how we can optimize CT dose in order to maximize the benefit-to-risk ratio of this clinically useful diagnostic imaging method.     

A review of dosimetry used in epidemiological studies considered to evaluate the linear no-threshold (LNT) dose-response model for radiation protection

Abstract

Background: Accurate dosimetry is key to deriving the dose response from radiation exposure in an epidemiological study. It becomes increasingly important to estimate dose as accurately as possible when evaluating low dose and low dose rate as the calculation of excess relative risk per Gray (ERR/Gy) is very sensitive to the number of excess cancers observed, and this can lead to significant errors if the dosimetry is of poor quality. By including an analysis of the dosimetry, we gain a far better appreciation of the robustness of the work from the standpoint of its value in supporting the shape of the dose response curve at low doses and low dose rates. This article summarizes a review of dosimetry supporting epidemiological studies currently being considered for a re-evaluation of the linear no-threshold assumption as a basis for radiation protection. The dosimetry for each study was evaluated based on important attributes from a dosimetry perspective. Our dosimetry review consisted of dosimetry supporting epidemiological studies published in the literature during the past 15 years. Based on our review, it is clear there is wide variation in the quality of the dosimetry underlying each study. Every study has strengths and weaknesses. The article describes the results of our review, explaining which studies clearly stand out for their strengths as well as common weaknesses among all investigations.

Purpose: To summarize a review of dosimetry used in epidemiological studies being considered by the National Council on Radiation Protection and Measurements (NCRP) in an evaluation of the linear no-threshold dose-response model that underpins the current framework of radiation protection.

Materials and methods: The authors evaluated each study using criteria considered important from a dosimetry perspective. The dosimetry analysis was divided into the following categories: (1) general study characteristics, (2) dose assignment, (3) uncertainty, (4) dose confounders (5) dose validation, and (6) strengths and weaknesses of the dosimetry. Our review focused on approximately 20 studies published in the literature primarily during the past 15 years.

Results: Based on the review, it is clear there is wide variation in the quality of the dosimetry underlying each study. Every study has strengths and weaknesses. This paper describes the results of our review, identifies common weaknesses among all investigations, and recognizes studies that clearly stand out for their overall strengths.

Conclusions: The paper concludes by offering recommendations to investigators on possible ways in which dosimetry could be improved in future epidemiological studies.     

大剂量增强MR检查对脑部病变的诊断价值

探讨大剂量增强ＭＲ检查对显示脑部隐匿性小病灶以及改善病灶的显示和诊断的准确性。材料与方法：７４例脑部病变包括肺癌脑转移,乳腺癌脑转移,爱滋病脑弓形体病,胶质母细胞瘤,脑膜瘤,分别进行标准剂量和大剂量增强ＭＲ检查,两次查间隔时间不超过３天。     

Strategies for reduction of radiation dose in cardiac multislice CT

Because cardiac computed tomography (CT) (mainly coronary CT angiography) is a very promising technique, used more and more for coronary artery evaluation, the benefits and risks of this new low-invasive technique must be balanced. Radiation dose is a major concern for coronary CT angiography, especially in case of repeated examinations or in particular subgroups of patients (for example young female patients). Radiation dose to patient tends to increase from 16- to 64-slice CT. Radiation exposure in ECG-gated acquisitions may reach up to 40 mSv; considerable differences are attributable to the performance of CT machines, to technical dose-sparing tools, but also to radiological habits. Setting radiation dose at the lowest level possible should be a constant goal for the radiologist. Current technological tools are detailed in regard to their efficiency. Optimisation is necessary, by a judicious use of technological tools and also by individual adaptation of kV or mAs. This paper reviews the different current strategies for radiation dose reduction, keeping image quality constant. Data from the literature are discussed, and future technological developments are considered in regards to radiation dose reduction. The particular case of paediatric patients with congenital heart disease is also addressed.     

数字乳腺X射线摄影中管电流量优化的实验研究

目的:探讨数字乳腺X射线摄影中不同靶/滤过组合时降低管电流量(mAs)对图像质量与辐射剂量的影响。方法:不同靶/滤过组合时,以自动曝光模式(AEC)的mAs为基础,分别降低10%、20%、30%、40%、50%时对厚度为4.4 cm的模体进行曝光,测量所得图像的对比噪声比(CNR)、信噪比(SNR)、品质因子(FOM)...     

加速器机载kV锥形束CT有效剂量的分析

目的 分析医用直线加速器机载kV锥形束CT扫描过程中患者的有效剂量随扫描条件的变化.方法 用PTW TM30009电离室分别在T40017头模和T40016躯干模体中,改变XVI锥形柬CT的管电压、毫安秒、准直器以及机架旋转范围等参数测量加权CT剂鼍指数,计算相应的剂量长度乘积和有效剂量.结果 kV锥形束CT的加权剂量指数和有效剂量随管电压呈二次方变化,随毫安秒线性变化,与准直器以及机架旋转范围密切相关.临床常用条件下,kV锥形束CT单次扫描的剂最长度乘积和有效剂量低于参考剂量水平.结论 锥形束CT扫描过程中患者接受的有效剂量与扫描条件密切相关.锥形束CT扫描时,应该根据患者的解剖部位合理选择成像参数,最大限度减少患者接受剂量.