Medical exposures based on the survey of the X-ray technical conditions and the proposal of guidance level

The purpose of this work was to propose guidance levels of entrance surface doses for radiographic examinations of Japanese patients based on a nationwide survey. Questionnaires asking about the technical conditions of radiography were sent to 2,000 hospitals in Japan. The entrance doses (1st quartile, median, 3rd quartile, and mean) were calculated by the Numerical Dose Determination (NDD) method described in this paper and by using the conditions reported in the questionnaires. Our results for all types of examinations showed that the median was lower than the mean, whereas the median was higher than the mean in the results reported in the British NRPB 21. The median of our results was lower than that in the NRPB in England (Present work/NRPB in England = 0.27-0.74). We propose guidance levels of entrance surface doses for examinations carried out in Japanese institutions as the 3rd quartile of the dose distributions. The present proposed levels are lower than those described by IAEA. The calculated entrance surface doses exceeded the guidance levels set by IAEA in less than 10% of the institutions surveyed.     

我国X射线摄影程序受检者入射体表剂量调查结果与分析

目的 通过调查全国15个省市不同级别医疗机构使用数字和屏片设备开展X射线摄影时受检者的入射体表剂量（ESD）,为制定适合我国国民体质特征的X射线摄影诊断参考水平提供数据。方法 按照《医用辐射危害评价与控制技术研究》实施方案的要求,选择年龄在20~70岁的受检者,男性体重在55~80 kg,女性体重在50~70 kg;采用热释光探测器（TLD）测量不同X射线摄影程序中成人受检者ESD,每台设备同一体位患者应不少于10名受检者;测量部位包含头颅、胸部的后前位（PA）和侧位（LAT）,腹部、骨盆、腰椎、胸椎的前后位（AP）和腰椎、胸椎的LAT等。结果 共在全国15个省的342家医院调查了19 975例X射线摄影受检者,1 813台不同类型X射线摄影设备,包括屏片X射线摄影、计算机X射线摄影（CR）和直接数字化X射线摄影（DR）设备,对于这3种类型的设备,不同摄影体位时受检者ESD的平均值分别为头颅PA：1.75、1.90、1.15 mGy;头颅LAT：1.69、1.46、1.03 mGy;胸部PA：0.75、0.65、0.36 mGy;胸部LAT：1.81、1.26、0.88 mGy;腹部AP：4.37、3.77、2.15 mGy;骨盆AP：3.73、3.56、2.75 mGy;腰椎AP：5.49、5.84、4.17 mGy;腰椎LAT：12.01、9.37、6.82 mGy;胸椎AP：4.53、3.65、2.49 mGy;胸椎LAT：6.91、6.43、4.15 mGy。结论 不同照射部位X射线摄影致受检者ESD有较大的差异。DR设备致受检者的ESD均低于屏片设备;除胸椎AP外,DR设备致受检者ESD均低于CR设备。在所有检查部位中,CR和屏片设备所致受检者ESD的差异均无统计学意义。     

Patient and staff exposure during endoscopic retrograde cholangiopancreatography

Despite a number of efforts being put into the radiological protection of both patient and staff during interventional radiological (IR) procedures during recent years, information about radiation exposure during endoscopic retrograde cholangiopancreatography (ERCP) procedures remains scarce. The purpose of this study was to estimate both patient and staff radiation doses during therapeutic ERCP procedures by direct measurement and to compare these results with data from other IR procedures. For 54 patients, effective dose and skin dose were estimated by measuring the dose-area product. For staff, entrance surface doses to the lens of the eye, thyroid and hands were estimated by thermoluminescent dosemeters. A median effective dose of 7.3 mSv and a median entrance surface dose of 271 mGy per procedure were estimated for patients. The gastroenterologist received a median dose of 0.34 mGy to the lens of the eye, 0.30 mGy to the skin at the level of the thyroid and 0.44 mGy to the skin of the hands, per procedure. When comparing the dosimetric quantities presented in this study with data from other IR procedures, it is clear that patient skin doses and doses to staff are high owing to the use of inappropriate X-ray equipment. ERCP requires the same radiation protection practice as all IR procedures. It should be consistently included in future multicentre IR patient and staff dose survey studies at national or international level.     

广西X射线诊断受检者体表入射剂量调查

目的 探讨广西X射线诊断受检者体表入射剂量。方法 分层随机抽样选取25家不同级别医院的2 236例X射线诊断受检者为调查对象,采用热释光剂量测量不同级别的医院、不同类型设备和不同照射部位受检者的体表入射剂量。结果 普通X射线摄影、计算机X射线摄影(CR)和直接数字化X射线摄影(DR)受检者体表入射剂量范围分别为0.08~31.51、0.11~4.25和0.05~35.63 mGy。腹部前后位(AP)、骨盆AP;头颅侧位(LAT)、头颅后前位(PA)、胸部PA、胸部LAT、胸椎AP、胸椎LAT、腰椎AP、腰椎LAT入射剂量范围分别为0.08~19.53、0.15~18.78、0.08~9.87、0.06~9.24、0.05~2.71、0.13~2.93、0.15~19.01、0.07~25.33、0.16~27.23和0.11~35.63 mGy。结论 广西X射线诊断受检者平均入射剂量达标,但部分DR摄影致胸部PA入射剂量超过医疗照射指导水平。     

河南省X射线摄影成年受检者入射体表剂量调查

目的 调查河南省X射线摄影致成年受检者的入射体表剂量水平,为建立适合我国国民体质特征的放射诊断受检者剂量指导水平提供技术和数据支持。方法 采用非概率抽样方法选取河南省郑州、开封和信阳3个地市14家医院,用热释光剂量测量方法调查普通X射线摄影、计算机X射线摄影（CR）和直接数字化X射线摄影（DR）不同照射部位1 404名受检者入射体表剂量水平。结果 河南省普通X射线摄影、CR摄影和DR摄影致成年受检者入射体表剂量范围分别为0.20~47.71、0.16~6.89和0.10~10.41 mGy。腹部前后位（AP）、骨盆AP、头颅侧位（LAT）、头颅后前位（PA）、胸部LAT、胸部PA、胸椎AP、胸椎LAT、腰椎AP、腰椎LAT摄影入射体表剂量范围分别为0.16~10.05、0.20~10.36、0.11~2.13、0.10~2.92、0.39~5.85、0.12~1.82、0.16~11.67、0.36~29.37、0.25~14.49和1.18~47.71 mGy。普通X射线摄影致受检者入射体表剂量高于CR和DR摄影,差异有统计学意义（Z=-8.709、-9.570,P<0.05）。普通X射线摄影胸部PA、腰椎LAT入射体表剂量高于全国“九五”期间调查结果,差异有统计学意义（Z=3.262、2.538,P<0.05）。结论 河南省普通X射线摄影和CR摄影所致受检者胸部PA和LAT入射体表剂量超过医疗照射指导水平,普通X射线摄影部分照射部位入射体表剂量较全国“九五”期间调查结果有所提高。     

A baseline study of entrance dose and image quality for lumbar spine radiography in Calabar, Nigeria

PurposeTo obtain baseline data for implementing optimisation protocols in Nigeria, a study of the patient entrance surface doses (ESDs) and image quality for lumbar radiography in the two major hospitals in Calabar, Nigeria has been carried out.MethodA total of 74 patients cutting across the two hospitals were monitored during lumbar X-ray examination for entrance surface doses (ESDs) using Lithium Fluoride Thermoluminescent dosimeters (LiF-TLDs). Image quality of ensuing radiographs was studied by three experienced Radiologists using the European Commission (EC) criteria for lumbar radiography.ResultsMean patient entrance dose for the studied population was about 10.5 mGy (AP) and 23.1 mGy for the lateral projection. Third quartile ESD values suggest that up to 75% of the exposed population in lumbar radiography may be receiving doses above the EC reference level. Image quality scores against a reference image were marginally above average. There was no correlation between dose and image quality per radiograph. Results confirm the need for optimisation of procedure in the area.ConclusionProcedural changes are suggested in order to lower the patient doses and improve on the image quality of radiographs. These results are to be used as a reference for future review after the optimisation protocol is put in place.     

Does digital acquisition reduce patients' skin dose in cardiac interventional procedures? An experimental study

OBJECTIVE: It is necessary to reduce the exposure doses from both fluoroscopy and angiocardiography. Pulsed fluoroscopy clearly reduces patients' exposure. By contrast, whether digital acquisition reduces patients' exposure is not clear. This study simulated the skin radiation doses of patients in cardiac catheterization laboratories with various radiography systems used in percutaneous transluminal coronary angioplasty to determine whether digital acquisition reduces patient exposure as compared with cine film recording. MATERIALS AND METHODS: The entrance surface doses with cineangiography and fluoroscopy of acrylic phantoms were compared for 11 radiography systems at seven facilities; each performs more than 100 cardiac intervention procedures per year. The entrance surface dose for an acrylic plate (20 cm thick) was measured using a skin-dose monitor. RESULTS: The maximum dose exceeded the minimum dose by 6.44 times for cineangiography and by 3.42 times for fluoroscopy. The entrance surface dose with acrylic plate was lower with digital-only acquisition (mean +/- SD, 3.07 +/- 0.84 mGy/sec) than with film recording (6.00 +/- 3.04 mGy/sec). By contrast, the entrance surface frame dose, after correction for the cine frame rate, tended to be higher with digital acquisition than with film recording (0.210 +/- 0.053 vs 0.179 +/- 0.058 mGy/frame, respectively). CONCLUSION. The entrance surface dose was approximately 50% less with digital-only acquisition than with film recording. However, after correcting the dose for cine frame rate, filmless acquisition did not in itself reduce the exposure. For the surface dose to be reduced for cardiac interventional radiography, even with digital filmless radiography systems, a low recording speed is necessary for angiocardiography.     

Organ doses from cardiac and carotid digital subtraction angiography

Estimates of mean organ doses from cardiac and carotid digital subtraction angiography (DSA) are obtained from measurements done using a Rando-Alderson tissue-equivalent phantom. Thermoluminescent dosemeter chips and discs were calibrated and used for all measurements in the primary and scattered radiation fields. Skin doses as well as mean doses received by the thyroid, lung, lens of the eye, breast, uterus and the ovaries were measured. A 30 degree right anterior oblique (RAO) cardiac DSA study produces a beam entrance dose of about 121 mGy at a rate of 0.48 mGy/frame. The highest mean organ dose from cardiac DSA was to the lung with a value of 14.4 mGy. The rest of the organs received doses below 1 mGy. In carotid DSA, the mean entrance doses resulted from the RAO, left anterior oblique, and the Towne's view projections give an average of 168 mGy at a rate of 8.4 mGy/frame. The highest mean organ dose from the three projections, 21 mGy, was received by the thyroid. The uterus and ovaries received the lowest doses from both procedures with values below 0.04 mGy. Patient and phantom surface exposures were compared using an exposure area product system. Hence, exposure conditions used for measuring organ doses on the phantom were adjusted to resemble those used for patients.     

National Survey of Radiation Doses of Pediatric Chest Radiography in Korea: Analysis of the Factors Affecting Radiation Doses

Objective

To investigate radiation doses in pediatric chest radiography in a national survey and to analyze the factors that affect radiation doses.

Materials and Methods

The study was based on the results of 149 chest radiography machines in 135 hospitals nationwide. For each machine, a chest radiograph was obtained by using a phantom representing a 5-year-old child (ATOM® dosimetry phantom, model 705-D, CIRS, Norfolk, VA, USA) with each hospital''s own protocol. Five glass dosimeters (M-GD352M, Asahi Techno Glass Corporation, Shizuoka, Japan) were horizontally installed at the center of the phantom to measure the dose. Other factors including machine''s radiography system, presence of dedicated pediatric radiography machine, presence of an attending pediatric radiologist, and the use of automatic exposure control (AEC) were also evaluated.

Results

The average protocol for pediatric chest radiography examination in Korea was 94.9 peak kilovoltage and 4.30 milliampere second. The mean entrance surface dose (ESD) during a single examination was 140.4 microgray (µGy). The third quartile, median, minimum and maximum value of ESD were 160.8 µGy, 93.4 µGy, 18.8 µGy, and 2334.6 µGy, respectively. There was no significant dose difference between digital and non-digital radiography systems. The use of AEC significantly reduced radiation doses of pediatric chest radiographs (p < 0.001).

Conclusion

Our nationwide survey shows that the third quartile, median, and mean ESD for pediatric chest radiograph is 160.8 µGy, 93.4 µGy, and 140.4 µGy, respectively. No significant dose difference is noticed between digital and non-digital radiography systems, and the use of AEC helps significantly reduce radiation doses.     

Radiation exposure to patient and radiologist during transcatheter arterial embolization for hepatocellular carcinoma

PURPOSE: To evaluate radiation exposure to patients and radiologists during transcatheter arterial embolization(TAE) for hepatocellular carcinoma. MATERIALS AND METHODS: In 39 TAE procedures performed at eight institutes, skin doses were evaluated with thermoluminescence dosimeters at the patient's back(entrance surface) and lower abdomen, and at the radiologist's forehead and abdomen. Real-time dosimeters were also used to evaluate patient skin dose. RESULTS: The patients' mean entrance surface dose was 973 +/- 681 mGy(range, 185 to 3543 mGy) with the mean fluoroscopic time of 21 minutes and 6 digital subtraction angiography(DSA) acquisitions. The dose at the patients' lower abdomen was 0.98 +/- 0.77 mGy. Doses for the radiologists were 0.04 +/- 0.04 mGy at the forehead and 0.15 +/- 0.19 mGy and 0.005 +/- 0.01 mGy at the abdomen over and under the apron, respectively. Fifty-six percent of the patients' skin dose was from DSA and 44% from fluoroscopy. CONCLUSIONS: Patient skin dose may occasionally exceed the dose for transient erythema. Because a patient may have repeated TAEs, skin doses or X-ray conditions should be recorded. The exposed doses of radiologists were considered to be acceptable with proper techniques. Further efforts to reduce radiation should be directed toward both DSA and fluoroscopy.     

Entrance skin dose estimates derived from dose-area product measurements in interventional radiological procedures.

Patient skin doses resulting from interventional radiological procedures have the potential to exceed threshold doses for deterministic effects such as erythema and epilation. If the irradiation geometry is known, the entrance skin dose can be estimated from the measured dose-area product. For each of 10 non-coronary interventional procedures, a nominal geometry was identified. From a previous survey of patient dose-area products, the entrance skin doses were estimated under the assumption that all procedures were performed with the nominal geometry specific to it. An analysis of the uncertainties in these doses caused by realistic deviations from the nominal geometry was also performed and it was shown that the estimated entrance skin dose values are at least to within 40%, and generally to within about 30%, of those actually received. For example, the median estimated entrance skin doses for the posteroanterior and lateral projections of cerebral angiography were 100 and 110 mGy. respectively, and for hepatic angiography 425 mGy. The largest entrance skin dose estimate for a single projection was for the angiography component of a CT arterial portography procedure at 670 mGy. Comparisons between entrance skin dose estimates obtained from this study are made with data from other interventional radiology patient dose surveys.     

我国CT扫描检查中受检者剂量调查结果与分析

目的 通过调查全国15个省市不同级别医疗机构的CT扫描参数并计算受检者剂量,分析我国CT检查中受检者剂量水平,为建立适合我国国民体质特征的CT诊断参考水平提供依据。方法 按照《医用辐射危害评价与控制技术研究》实施方案要求,调查临床实际CT扫描中受检者信息和CT扫描参数,根据临床受检者实际扫描参数,使用CT电离室测量CT设备的CT剂量指数（包括CTDI₁₀₀、CTDI_W和CTDI_VOL）,计算代表受检者剂量的剂量长度乘积（DLP）。结果 共在全国15个省市的166家医院调查的483台次不同类型CT扫描设备上,调查了6 524例CT扫描程序。对于头颅、胸部、腹部和腰椎等不同的CT扫描部位,其加权CT剂量指数（CTDI_W）平均值分别为43、15、19和25 mGy,第75百分位数分别为50、19、23和32 mGy;相应DLP的平均值分别为540、397、503和376 mGy·cm,第75百分位数分别为659、525、632和479 mGy·cm。结论 通过此次调查基本上掌握了我国部分省市CT扫描检查中受检者剂量,本次4种部位受检者剂量的第75百分位数,与其他国家和地区的出版物中给出的诊断参考水平互有高低,提示应根据我国国民体质特征,建立适合本国或者不同地区的CT检查中受检者诊断参考水平的重要性,推动CT检查的医疗照射防护最优化。     

Survey of pediatric MDCT radiation dose from university hospitals in Thailand: a preliminary for national dose survey

Background Increasing pediatric CT usage worldwide needs the optimization of CT protocol examination. Although there are previous published dose reference level (DRL) values, the local DRLs should be established to guide for clinical practice and monitor the CT radiation. Purpose To determine the multidetector CT (MDCT) radiation dose in children in three university hospitals in Thailand in four age groups using the CT dose index (CTDI) and dose length product (DLP). Material and Methods A retrospective review of CT dosimetry in pediatric patients (<15 years of age) who had undergone head, chest, and abdominal MDCT in three major university hospitals in Thailand was performed. Volume CTDI (CTDI(vol)) and DLP were recorded, categorized into four age groups: <1 year, 1-< 5 years, 5-<10 years, and 10-<15 years in each scanner. Range, mean, and third quartile values were compared with the national reference dose levels for CT in pediatric patients from the UK and Switzerland according to International Commission on Radiological Protection (ICRP) recommendation. Results Per age group, the third quartile values for brain, chest, and abdominal CTs were, respectively, in terms of CTDI(vol): 25, 30, 40, and 45 mGy; 4.5, 5.7, 10, and 15.6 mGy; 8.5, 9, 14, and 17 mGy; and in terms of DLP: 400, 570, 610, and 800 mGy cm; 80, 140, 305, and 470 mGy cm; and 190, 275, 560,765 mGy cm. Conclusion This preliminary national dose survey for pediatric CT in Thailand found that the majority of CTDI(vol) and DLP values in brain, chest, and abdominal CTs were still below the diagnostic reference levels (DRLs) from the UK and Switzerland regarding to ICRP recommendation.     

北京市放射诊断受检者剂量调查与分析

目的 探讨北京地区放射诊断检查对成年受检者的辐射剂量水平。方法 选取北京市城区与远郊共10个区域的30家不同级别医疗机构,以1 182例X射线摄影、542例乳腺摄影和410例CT检查为研究对象,测读不同投照部位下照射野内受检者/模体所受的辐射剂量。结果 普通X射线摄影、CR摄影和DR摄影受检者剂量范围分别为0.4~24.1、0.3~13.9、0.1~15.9 mGy;乳腺受检者乳腺腺体平均剂量为0.3~5.4 mGy;CT受检者CTDI_w值为28.1~96.3 mGy、CTDI_vol值为7.0~23.4 mGy、DLP值为162.2~898.1 mGy ·cm。结论 个别放射诊断检查受检者所受辐射剂量高于国标中医疗照射指导水平值,应引起注意。     

Quality control and diagnostic reference levels in intraoral dental radiographic facilities

OBJECTIVES: A quality control program in intraoral radiographic equipment was conducted aiming to verify compliance with the latest legal requirements and to measure radiation dose in order to contribute to the establishment of appropriate diagnostic reference levels. METHODS: This study was performed in 191 intraoral radiographic facilities in Northern Greece. The quality control program included visual inspection of the unit, registration of its characteristics, measurement and calculation of several radiological parameters, including entrance surface dose, and overall compliance with legislation requirements. RESULTS: Most units (61.8%) were found to perform within their corresponding specifications. Exposure timer accuracy was the parameter that the dental units showed the poorest performance. Inadequate beam filtration was found in almost half of the older 50 kVp units. Entrance surface dose showed significant discrepancies, varying from 0.30 mGy to 16.09 mGy with a third quartile value of 3.37 mGy. CONCLUSIONS: A diagnostic reference level of 3.5 mGy is considered to be a realistic value for all intraoral equipment currently operating in Greece. However, for newly installed units, a value of 2.8 mGy is considered to be more appropriate.     

A study of optimum radiographic conditions on chest examinations with computed radiology (CR) in conjunction with the offset balance of patient dose and image quality]

In a report of a nationwide survey on radiographic conditions of chest radiography in Japan, it was pointed out that the average entrance surface dose (ESD) of the computed radiography (CR) system was higher than that of the film-screen system. It seemed important that an objective index and criteria be established for dose reduction without a loss of image quality that would interfere with diagnostic observation. For this purpose, we investigated the properties of root of mean square (RMS) granularity, since it is a dominant factor in CR image quality and strongly depends on dose. The results indicated that RMS granularity showed little dependence on tube voltage when relative exposure was kept constant and that it decreased with the increment of exposure and approached a finite minimum value in a very high exposure region. For the most frequently used radiographic conditions in Japan (120 kV, 2.5 mmAl, 200 cm SID, 10: 1 grid), the decrement in RMS granularity from 6 to 16 mAs was 0.0276 to 0.0253 (9.1%). This finding suggested that exposure exceeding 6 mAs did not improve image quality, i.e., exposure reduction down to 6 mAs would not cause a significant loss of image quality. It was therefore concluded that RMS granularity was a useful objective index by which to determine the upper limit of exposure. Use of the most frequent conditions with 6 mAs seemed to be recommendable as an initial condition for the technical optimization of CR chest radiography, since ESD under this condition was 0.265 mGy, which was approximately equal to the value of the ESD distribution of a total chest radiogram in Japan.     

两种数字化X射线摄影技术影像质量与成像剂量的比较

目的对比研究非晶硒平板探测器直接数字化X射线摄影(DR)及计算机x射线摄影(CR)两种数字化X射线摄影技术影像质量与吸收剂量的关系。方法应用DR和CR系统分别对对比度．细节体模(CDRAD2．0)进行不同吸收剂量的曝光成像。记录每次曝光的体模表面吸收剂量，并将所获取的影像在图像诊断工作站显示器上由4位观片者进行观察，计算影像质量表征因子(IQF)。应用ANOVA检验法统计、比较两种数字化摄影技术的图像质量与吸收剂量的差别。结果与CR相比，DR具有更低的IQF值，对人体组织对比度和结构细节有更好的信息检出特性。两种成像技术产生相同IQF值时，DR系统在体模表面产生的表面剂量比CR系统降低了77％。结论DR技术对于低对比度组织细节的检测好于CR技术。在获得相同影像信息的前提下，与CR相比应用DR大大降低了被检者吸收剂量。     

X射线胸部摄影曝光剂量与图像质量相关性研究

目的 研究数字化X射线胸部高千伏摄影曝光剂量与图像质量的关系,确定数字化X射线摄影最佳曝光剂量。方法 选择胸部高千伏摄影管电压120 kV,摄影mAs从1 mAs逐档增加至25 mAs,对模拟人体胸部厚度摄影体模与CDRAD 2.0对比度细节体模进行摄影,测量体模表面X射线入射剂量,由5位观察者独立阅读体模影像,比较任意两曝光条件组之间的图像质量因子（IQF）,确定高千伏胸部摄影最佳条件。比较4和10 mAs条件下正常人体胸部摄影图像质量评分。结果 胸部高千伏摄影体模曝光条件从1 mAs增加到25 mAs,体模表面X射线入射剂量从0.067 mGy增加至1.468 mGy。随着X射线入射剂量的增加,影像质量影响因子IQF值不断减小,观察者阅读体模信号的IQF差异有统计学意义（F=31.00,P<0.05）,曝光剂量条件选择在1~4 mAs时所对应的IQF均值差异有统计学意义（F=15.3,P<0.05）,4~10 mAs时所对应的IQF差异无统计学意义,10~25 mAs时所对应的IQF均值差异有统计学意义（F=9.74,P<0.05）。曝光剂量条件选择4和10 mAs所对应的体模表面入射剂量为0.250和0.606 mGy,两种条件下胸部图像质量的综合评分分别为（24.8±1.64）、（25.8±2.05）分,差异无统计学意义。结论 随着数字化X射线摄影剂量的增加所获得图像信息量增加。满足临床诊断的标准人体胸部高千伏数字化X摄影最佳剂量为0.250 mGy左右。     

内蒙古自治区常规X射线诊断患者剂量调查结果分析

目的 分析内蒙古地区常规X射线诊断患者入射体表剂量水平。方法 根据全国医疗照射剂量及频度调查项目方案的要求,完成内蒙古地区30%数量医疗机构常规X射线诊断应用现状调查,按照医疗机构年接诊人数比例抽取内蒙古地区12个盟市24家医疗机构开展普通X射线诊断患者入射体表剂量调查。将不同设备、不同级别医院、不同照射部位间受检者入射体表剂量结果进行比较。结果 在各类诊断设备中,以数字X射线摄影系统（DR）为主。在各类常规X射线诊断检查过程中,腰椎摄影所致患者平均入射体表剂量为3.39 mGy/人,骨盆及髋关节摄影检查所致患者平均入射体表剂量为1.65 mGy/人,颈椎、四肢和胸部摄影所致患者平均入射体表剂量分别为0.90、0.38、0.37 mGy/人。在胸部、腰椎、颈椎3种部位的诊断检查中,使用屏片摄影设备所致受检者入射体表剂量高于DR测量结果,差异具有统计学意义（Z=-3.229、-4.820、-5.265,P<0.05）。结论 屏片摄影设备所致患者的入射体表剂量大于DR,操作人员的操作行为是影响患者入射体表剂量的重要因素。     

A dose comparison survey in CT departments of dedicated paediatric hospitals in Australia and Saudi Arabia

AIM: To measure and compare computed tomography (CT) radiation doses delivered to patients in public paediatric hospitals in Australia and Saudi Arabia. METHODS: Doses were measured for routine CT scans of the head, chest and abdomen/pelvis for children aged 3-6 years in all dedicated public paediatric hospitals in Australia and Saudi Arabia using a CT phantom measurement cylinder.RESULTS: CT doses, using the departments’ protocols for 3-6 year old, varied considerably between hospitals. Measured head doses varied from 137.6 to 528.0 mGy·cm, chest doses from 21.9 to 92.5 mGy·cm, and abdomen/pelvis doses from 24.9 to 118.0 mGy·cm. Mean head and abdomen/pelvis doses delivered in Saudi Arabian paediatric CT departments were significantly higher than those in their Australian equivalents. CONCLUSION: CT dose varies substantially across Australian and Saudi Arabian paediatric hospitals. Therefore, diagnostic reference levels should be established for major anatomical regions to standardise dose.