Evaluation of Radiation Exposure Literacy among Mammography Examinees Using Radiation Dose Distribution in Mammography Examinations

Introduction: Radiation is indispensable for diagnosis and treatment and is widely used in medicine. This study aimed to determine patients’ knowledge and ability to understand radiation exposure to assess the usefulness of providing information on radiation doses to examinees. Material and Methods: The radiation exposure literacy of mammography examinees was assessed using a new scale consisting of the following five items: “collection of information from various sources”, “selection of information necessary for oneself”, “understanding and communication of information”, “judgment of the reliability of information”, and “ability to plan and act based on information”. We analyzed the relationship of these items with examinees’ attributes and clarified the level of understanding of radiation exposure dose associated with mammography examinations by providing examinees with visual information in the form of color maps. Results: The relationship between “information collection” and several attributes of radiation exposure literacy was strong. In addition, providing visual information on radiation doses using dose distribution maps in mammography examinations could deepen the understanding of radiation doses among examinees. Conclusion: By understanding the radiation exposure literacy of examinees and comparing it with their attributes, it is possible to provide suggestions for developing methods of providing radiation dose information tailored to individual examinees. In addition, improving radiation exposure literacy will enable the development of skills necessary to provide safe medical care to medical examinees.

Application of Low Tube Voltage, Low-concentration Contrast Agent Using a 320-row CT in Coronary CT Angiography: Evaluation of Image Quality, Radiation Dose and Iodine Intake

The effect of low voltage and low concentration contrast agent on image quality of coronary CT angiography,radiation dose and iodine intake was evaluated.A total of 121 patients with body mass index(BMI)<26 kg/m2 and heart rate(HR)<70 beats/min were randomly divided into four groups:group A(n=31,80 kVp,270 mgl/mL);group B(n=33,100 kVp,270 mgl/mL);group C(h=30,100 kVp,320 mgl/mL);group D(w=27,100 kVp,400 mgl/mL).The automatic current modulation system and the iterative algorithm for reconstruction were adopted in each group.The CT values and SD values of the aortic root(AR),subcutaneous fat,left coronary artery opening(LCA),and right coronary artery opening(RCA)were measured in all groups,the signalto-noise ratio(SNR)and contrast noise ratio(CNR)were calculated,and effective radiation dose and iodine intake were recorded.The subjective assessment for image quality was performed by two physicians using a 4-point scale.The results were compared using the one-way ANOVA and rank sum tests.The image quality of the four groups met the clinical diagnostic requirements.The CT values of AR in groups A,B,C,and D were 537.6±71.4,447.2±81.9,445.2±64.9 and 518.5±94.9 Hu,respectively,with no significant difference between group A and group D,or between group B and group C,while CT values in groups B and C were significantly lower than those in groups A and D(P<0.05).In groups A,B,C,and D,the LCA SNR values were 22.7±9.1,23.3±9.1,23.3±7.7 and 26.6±8.9,and the RCA CNR values were 26.9±9.&28.5±11.4,27.7土&8 and 32」±10.6,respectively.The AR visual scores in groups A,B,C and D were 3.8±0.2,3.9±0.3,3.9±0.3 and 4.0±0.3,respectively.There were no significant differences in SNR,CNR and visual score among the four groups(P>0.05).The radiation doses in groups A,B,C and D were 2.6±1.4,3.6±1.&4.9±3.5 and 4.9±2.8 mSv,respectively.The radiation dose in group A was significantly less than that in the rest three groups(P<0.05).The iodine intakes in groups A,B,C and D were 14.9±1.5,15.0±1.5,17.7±2.0 and 18.1±2.5 g,respectively.There was no significant difference in the intake of iodine between groups C and D,or between groups A and B,while iodine intake in groups A and B were significantly reduced as compared with that in groups C and D(P<0.05).It was concluded that for patients with low BMI and controlled HR,compared to 100 kVp tube voltage combined with multiple concentration contrast agents,80 kVp combined with 270 mgl/mL contrast agent is enough to ensure the quality of the images,and can reduce the radiation dose significantly,while reducing the amount of iodine intake notably,thus reducing the incidence of adverse reaction.

Correlation between Low Tube Voltage in Dual Source CT Coronary Artery Imaging with Image Quality and Radiation Dose

The influence of low tube voltage in dual source CT（DSCT） coronary artery imaging on image quality and radiation dose and its application value in clinical practice were investigated. Totally, 300 cases of chest pain with low body mass index（BMI 〈18.5 kg/m2） subjected to DSCT coronary artery imaging were prospectively enrolled. The heart rate in all patients were greater than 65/min. The retrospective ECG gated scanning mode and simple random sampling method were used to assign the patients into groups A, B and C（n=100 each）. The patients in groups A, B and C experienced 120-, 100-, and 80-kV tube voltage imaging respectively, and the image quality was evaluated. The CT volume dose index（CTDIvol） and dose length product（DLP） were recorded, and the effective dose（ED） was calculated in each group. The image quality scores and radiation doses in groups were compared, and the influence of tube voltage on image quality and radiation dose was analyzed. The results showed that the excellent rate of image quality in groups A, B and C was 95.69%, 94.72% and 96.33% respectively with the difference being not statistically significant among the three groups（P〉0.05）. The CTDIvol values in groups A, B and C were 51.35±12.21, 21.28±7.13 and 6.34±3.34 mGy, respectively, with the difference being statistically significant（P〈0.05）. The ED values in groups A, B and C were 9.27±1.63, 4.56±2.29 and 2.29±1.69 mSv, respectively, with the difference being statistically significant（P〈0.05）. It was suggested that for the patients with low BMI, the application of DSCT coronary artery imaging with low tube voltage can obtain satisfactory image quality, and simultaneously, significantly reduce the radiation dose.

Comparison of radiation doses between hepatic artery infusion chemotherapy and transarterial chemoembolization for liver cancer

Objective:To analyze the radiation dose received by patients during hepatic artery infusion chemotherapy(HAIC)and transarterial chemoembolization(TACE)procedures and the related influencing factors.Methods:Data of 162 cases in the HAIC group and 230 cases in the TACE group were collected.The included covariates were Age(<45/45-59/≥60 years),BMI levels(underweight/normal weight/obesity),focus Dye of tumor(present/absent),lesion size(<5 cm/≥5 cm),superselection(present/absent),hepatic vascular variation(present/absent).The endpoints were postoperative dose-area product(DAP),exposure time and Air kerma(AK).Results:Of all included patients,the HAIC group patients were younger than those in the TACE group(P=0.028).The proportion of patients with large lesions in the HAIC group was higher than the TACE group(45.7%vs.33.9%,P=0.019).The proportion of patients who had superselection was lower in the HAIC group as compared to the TACE group(61.7%vs.82.2%,P<0.001).Generally,the HAIC group has lower DAP,exposure time and AK by 36.3%(P<0.001),38.2%(P<0.001),and 41.3%(P<0.001)than the TACE group,respectively.Linear regression analysis showed the procedure method(HAIC/TACE,P<0.001),type of DSA machine(Pheno/FD20,P<0.001),BMI levels(P<0.001),age(P=0.021),lesion size(<5 cm/≥5 cm,P=0.031)significantly correlated with low DAP.In the HAIC group,the type of DSA machine and BMI correlated with the radiation dose,while in the TACE group,the type of DSA machine,BMI,and lesion size correlated with the radiation dose.Conclusion:Compared with TACE,HAIC enables doctors and patients to receive lower radiation doses.Obese patients in both HAIC and TACE groups increase the radiation exposure in interventional doctors and patients,but large lesions only affect the radiation dose in the TACE procedure.

Radiation dose measurements in coronary CT angiography

Coronary computed tomography(CT)angiography has been recognized as the most rapidly developed imaging technique in the diagnosis of coronary artery disease due to the emergence and technological advances in multislice CT scanners.Coronary CT angiography has been confirmed to demonstrate high diagnostic and predictive value in coronary artery disease when compared to invasive coronary angiography.However,it suffers from high radiation dose which raises concerns in the medical field.Various dose-reduction strategies have been proposed with effective outcomes having been achieved to reduce radiation exposure to patients.This article provides an introduction and overview of the series of articles that will focus on each particular topic related to coronary CT angiography.

Truncus arteriosus:Diagnosis with dual-source computed tomography angiography and low radiation dose

Truncus arteriosus is an uncommon congenital cardiac abnormality which is characterized by a single arterial trunk origin from the heart that supplies both the systemic,pulmonary and coronary circulation.We present a preterm newborn female patient with type 2 truncusarteriosus,left superior vena cava and aberrant subclavian artery diagnosed with low dose dual-source cardiac computed tomography(CT).We discuss that low dose dual-source cardiac CT has more advantages than other imaging methods and it is an important modality for assessment of patients with conotruncal anomalies such as truncusarteriosus.

An evaluation of the influence of impurity concentration and composition in concrete on activation and radiation dose in the reactor facility

The content analysis of radioactive waste and radiation dose evaluation is considered as one of the important factors in the reactor facility design.This kind of buildings consists of the concrete for the most part and uses it as the structure and shield of the building.Generally,the concrete has impurities such as cobalt,europium,nickel,and cesium with specific content depending on the production method or manufacturing company.Dominant radioactive nuclides generated from the fundamental components of concrete are considered that it is less contributed to the radiation dose because they are beta decay nuclides in general.Thus,impurities of irradiated concrete in the reactor facilities,are considered occasionally an important evaluation factor for induced activity.In this study,the influence on the activation of impurities in concrete was evaluated from the radiation dose and induced activity calculations.The calculation was evaluated at the bio-shield which is one of the areas with the highest neutron irradiation among the concrete structure in the reactor facility.The results show that radioactive nuclides with gamma decay were produced in these impurities.Moreover,the radiation dose of concrete with impurities was higher than concrete without impurities.The increased radiation dose was quantified through the content of impurities.

Assessing radiation dose for postoperative radiotherapy in prostate cancer: Real world data

BACKGROUND Approximately 30%of patients with localized prostate cancer(PCa)who undergo radical prostatectomy will develop biochemical recurrence.In these patients,the only potentially curative treatment is postoperative radiotherapy(PORT)with or without hormone therapy.However,the optimal radiotherapy dose is unknown due to the limited data available.AIM To determine whether the postoperative radiotherapy dose influences biochemical failure-free survival(BFFS)in patients with PCa.METHODS Retrospective analysis of patients who underwent radical prostatectomy for PCa followed by PORT-either adjuvant radiotherapy(ART)or salvage radiotherapy(SRT)-between April 2002 and July 2015.From 2002 to 2010,the prescribed radiation dose to the surgical bed was 66-70 Gy in fractions of 2 Gy;from 2010 until July 2015,the prescribed dose was 70-72 Gy.Patients were grouped into three categories according to the total dose administered:66-68 Gy,70 Gy,and 72 Gy.The primary endpoint was BFFS,defined as the post-radiotherapy prostatespecific antigen(PSA)nadir+0.2 ng/mL.Secondary endpoints were overall survival(OS),cancer-specific survival(CSS),and metastasis-free survival(MFS;based on conventional imaging tests).Treatment-related genitourinary(GU)and gastrointestinal(GI)toxicity was evaluated according to Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria.Finally,we aimed to identify potential prognostic factors.BFFS,OS,CSS,and MFS were calculated with the Kaplan-Meier method and the log-rank test.Univariate and multivariate Cox regression models were performed to explore between-group differences in survival outcome measures.RESULTS A total of 301 consecutive patients were included.Of these,93(33.6%)received ART and 186(66.4%)SRT;22 patients were excluded due to residual macroscopic disease or local recurrence in the surgical bed.In this subgroup(n=93),43 patients(46.2%)were Gleason score(GS)≤6,44(47.3%)GS 7,and 6(6.5%)GS≥8;clinical stage was cT1 in 51(54.8%),cT2 in 35(39.3%),and cT3 in one patient(1.1%);PSA was<10 ng/mL in 58(63%)patients,10-20 ng/mL in 28(30.6%),and≥20 ng/mL in 6(6.4%)patients.No differences were found in BFFS in this patient subset versus the entire cohort of patients(P=0.66).At a median follow-up of 113 months(range,4-233),5-and 10-year BFFS rates were 78.8%and 73.7%,respectively,with OS rates of 93.3%and 81.4%.The 5-year BFFS rates in three groups were as follows:69.6%(66-68 Gy),80.5%(70 Gy)and 82.6%(72 Gy)(P=0.12):the corresponding 10-year rates were 63.9%,72.9%,and 82.6%(P=0.12),respectively.No significant between-group differences were observed in MFS,CSS,or OS.On the univariate analysis,the following variables were significantly associated with BFFS:PSA at diagnosis;clinical stage(cT1 vs cT2);GS at diagnosis;treatment indication(ART vs SRT);pre-RT PSA levels;and RT dose 66-68 Gy vs.72 Gy(HR:2.05;95%CI:1.02-4.02,P=0.04).On the multivariate analysis,the following variables remained significant:biopsy GS(HR:2.85;95%CI:1.83-4.43,P<0.001);clinical stage(HR:2.31;95%CI:1.47-4.43,P=0.01);and treatment indication(HR:4.11;95%CI:2.06-8.17,P<0.001).Acute grade(G)1 GU toxicity was observed in 11(20.4%),17(19.8%),and 3(8.3%)patients in each group(66-68 Gy,70 Gy and 72 Gy),respectively(P=0.295).Acute G2 toxicity was observed in 2(3.7%),4(4.7%)and 2(5.6%)patients,respectively(P=0.949).Acute G1 GI toxicity was observed in 16(29.6%),23(26.7%)and 2(5.6%)patients in each group,respectively(P=0.011).Acute G2 GI toxicity was observed in 2(3.7%),6(6.9%)and 1(2.8%)patients,respectively(P=0.278).No cases of acute G3 GI toxicity were observed.CONCLUSION The findings of this retrospective study suggest that postoperative radiotherapy dose intensification in PCa is not superior to conventional radiotherapy treatment.

Computed Tomography Protocol Optimisation for Pediatric Head Trauma: Radiation Dose and Image Quality Assessment

Purpose: Children are sometimes examined with Computed Tomography protocols designed for adults, leading to radiation doses higher than necessary. Lack of optimisation could lead to image quality higher than what is needed for diagnostic purposes with associated high doses to patients. Optimising the protocols for paediatric head trauma CT imaging will reduce radiation dose. Objective: The study aimed to optimise radiation dose and assess the image quality for a set of protocols by evaluating noise, a contrast to noise ratio, modulation transfer function and noise power spectrum. Methods: Somaton Sensation 64 was used to scan the head of an anthropomorphic phantom with a set of protocols. ImageJ software was used to analyse the paediatric head image from the scanner. IMPACTSCAN dosimeter software was used to evaluate the radiation dose to the various organs in the head. MATLAB was used to analyse the Modulation Transfer Function and the Noise Power. Results: The estimated Computed Tomography Dose Index volume (CTDIvol) increased with increasing tube current and tube voltage. The high pitch of 0.9 gave a lower dose than the 0.5 pitch. The eye lens received the highest radiation dose (39.2 mGy) whiles the thyroid received the least radiation dose (13.7 mGy). There was an increase in noise (62.46) when the H60 kernel was used and a lower noise (8.829) was noticed when the H30 kernel was used. Conclusion: The results obtained show that the H30 kernel (smooth kernel) gave higher values for noise and contrast to noise ratio (CNR) than the H60 kernel (sharp kernel). The H60 kernel produced high values for the modulation transfer function (MTF) and noise power spectrum (NPS). The eye lens received the highest radiation dose.

Structure the radiation dose curve of continuous slope

The traditional interpolation and fitting can not restore the radiation dose curve with the radiation source characteristic. Therefore, during the reduction the field of one dimensional radiation dose, the mathematical structure method was used to restore the curve with the dose value of the radioactive source is inversely proportional to the square of the distance from the radioactive source.

Evaluation of the Fetal-Maternal Radiation Doses in CT-Pelvimetry and Estimation of the Fetal Radiation Risks in 03 Radiology Departments in Douala-Cameroon

Background: CT in pregnant patients requires careful consideration of the radiation dose and corresponding radiation risks from ionizing radiation to the unborn child. The determination of foetal dose in diagnostic radiology is of interest as a basis for risk estimates from medical exposure of the pregnant patient. Objective: To evaluate the foetal-maternal radiation doses delivered during the CT-Pelvimetry procedure and to estimate the risk to the unborn child to develop a cancer in childhood and hereditary disease. Materials and Methods: We investigate the foetal-maternal radiation doses during CT-scan Pelvimetry in Douala (Cameroon). Data of 194 helical acquisition CT-Pelvimetry were collected between May 2017 and May 2019. An average DLP for the examination was established and the average effective dose was evaluated. The fetal dose was calculated and the FetDose V5 program was used for risk estimations. Results: The average dose length product (DLP) was 56.17 mGy·cm (range: 51.69 - 59.21 mGy·cm). The average effective dose received by women pregnant was 0.78 mSv. The mean individual fetal dose was 1.5 mGy (range: 0.76 - 1.87 mGy). The risk of Childhood Cancer calculated was: range 1 in 16,000 to 1 in 10,000 and 1 in 260,000 to 1 in 106,000 to the risk of Hereditary Disease, respectively. Conclusion: This study shows that the foetal-maternal doses delivered during CT-Pelvimetry examinations are very low and the risks of childhood cancers and hereditary diseases are derisory, the technology should be further investigated to ensure its full potential for optimal diagnostic accuracy.

Concurrent chemoradiotherapyof different radiation doses and different irradiation fields for locally advanced thoracic esophageal squamous cell carcinoma:A randomized,multicenter,phase Ⅲ clinical trial

Background:Concurrent chemoradiotherapy(CCRT)is the standard treatment for locally advanced esophageal squamous cell carcinoma(ESCC).However,the optimal radiotherapy regimen,particularly in terms of total dose and planned range of irradiation field,remains unclear.This phase III clinical trial aimed to compare the survival benefits between different radiation doses and different target fields.Methods:This trial compared two aspects of radiation treatment,total dose and field,using a two-by-two factorial design.The high-dose(HD)group received 59.4 Gy radiation,and the standard-dose(SD)group received 50.4 Gy.The involved field irradiation(IFI)group and elective nodal irradiation(ENI)group adopted different irradiation ranges.The participants were assigned to one of the four groups(HD+ENI,HD+IFI,SD+ENI and SD+IFI).The primary endpoint was overall survival(OS),and the secondary endpoints included progressionfree survival(PFS).The synergy indexwas used to measure the interaction effect between dose and field.Results:The interaction analysis did not reveal significant synergistic effects between the dose and irradiation field.In comparison to the target field,patients in IFI or ENI showed similar OS(hazard ratio[HR]=0.99,95%CI:0.80-1.23,p=0.930)and PFS(HR=1.02,95%CI:0.82–1.25).TheHDtreatment did not show significantly prolonged OS compared with SD(HR=0.90,95%CI:0.72–1.11,p=0.318),but it suggested improved PFS(25.2 months to 18.0 months).Among the four groups,the HD+IFI group presented the best survival,while the SD+IFI group had the worst prognosis.No significant difference in the occurrence of severe adverse events was found in dose or field comparisons.Conclusions:IFI demonstrated similar treatment efficacy to ENI in CCRT of ESCC.The HD demonstrated improved PFS,but did not significantly improve OS.The dose escalation based on IFI(HD+IFI)showed better therapeutic efficacy than the current recommendation(SD+ENI)and is worth further validation.

Life Time Attributable Cancer Risk Estimated Using Scanner Reported Dose Length Product during Chest Computed Tomography Imaging in Young Children

This study aims to estimate the lifetime attributable cancer risk (LAR) for pediatric chest computed tomography (CT) examinations in five age groups using recently published age and region-specific conversion coefficients multiplying the widely available scanner registered dose length products (DLP) displayed on the CT console and hence calculating the Effective Dose (ED). The ED is then multiplied by the International Commission on Radiological Protection (ICRP) published risk factor for LAR. The obtained LAR values are compared with the international literature. Factors that may affect the LAR value are reported and discussed. The study included one hundred twenty five chest CT examinations for both males and females aged from less than one year to fifteen years. The patients reported data are from one single medical institution and using two CT scanners from June 2022 to December 2023. The results of this study may serve as benchmark for institutional radiation dose reference levels and risk estimation.

Effects of Low Dose Radiation on Tumor Apoptosis, Cell Cycle and Apoptosis-Related Protein Bcl-2 in Tumor-Bearing Mice

To study the effects of low dose radiation (LDR) on tumor apoptosis, cellcycle progression and changes of apoptosis-related protein Bcl-2 in tumor-bearing mice. Methods:Male mice of Kunming strain were implanted subcutaneously with S180 sarcoma cells in the left inguenas an in situ experimental animal model. Seven days later, the mice were subjected to 75 mGywhole-body γ-irradiation. At 24 and 48 h after the irradiation, all mice were sacrificed. The tumorsizes were measured, and tumor cell apoptosis and cell cycle progression were analyzed by flowcytometry. The expression of apoptosis-related protein Bcl-2 and the apoptotic rate of tumor cellswere observed by immunohistochemistry and electron microscopy. Results: Tumors grew significantlyslower after LDR (P 【 0.05). The tumor cells were arrested in G1 phrase and the expression of Bcl-2protein decreased at 24 h. Apoptotic rate of tumor cells was increased significantly at 48 h afterLDR (P 【 0.01). Conclusion: LDR could cause a G1-phase arrest and increase the apoptosis of tumorcells through the low level of apoptosis-related protein bcl-2 in the tumor-bearing mice. Theorganized immune function and anti-tumor ability are markedly increased after LDR. Our studyprovides practical evidence of clinical application to cancer treatment.

0Optimized Fluoroscopy Setting and Appropriate Project Position Can Reduce X-ray Radiation Doses Rates during Electrophysiology Procedures

Background：Nonfluoroscopic three-dimensional electroanatomical system is widely used nowadays,but X-ray remains indispensable for complex electrophysiology procedures.This study aimed to evaluate the value of optimized parameter setting and different projection position to reduce X-ray radiation dose rates.Methods：From June 2013 to October 2013,105 consecutive patients who underwent complex ablation were enrolled in the study.After the ablation,the radiation dose rates were measured by two different settings （default setting and optimized setting） with three projection positions （posteroanterior [PA] projection;left anterior oblique [LAO] 30° projection;and LAO 45° projection）.The parameter of preset voltage,pulse width,critical voltage,peak voltage,noise reduction,edge enhancement,pulse rate,and dose per frame was modified in the optimized setting.Results：The optimized setting reduced radiation dose rates by 87.5％ （1.7 Gy/min vs.13.6 Gy/min,P ＜ 0.001） in PA,87.3％ （2.5 Gy/min vs.19.7 Gy/min,P＜0.001） in LAO 30°,85.9％ （3.1 Gy/min vs.22.1 Gy/min,P ＜ 0.001） in LAO 45°.Increase the angle of projection position will increase the radiation dose rate.Conclusions：We can reduce X-ray radiation dose rates by adjusting the parameter setting of X-ray system.Avoiding oblique projection of large angle is another way to reduce X-ray radiation dose rates.

Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors

Background：Contrast dose and radiation dose reduction in computerized tomography （CT） scan for adult has been explored successfully,but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations.This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction （ASiR） for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors.Methods：Forty-five patients with solid tumors who had initial CT （Group B） and follow-up CT （Group A） after chemotherapy were enrolled.The initial diagnostic CT scan （Group B） was performed using the standard two-phase enhanced CT with 320 mgI/ml concentration contrast,and the follow-up scan （Group A） was performed using a single-phase enhanced CT at 45 s after the beginning of the 270 mgI/ml contrast injection using spectral mode.Forty percent ASiR was used for the images in Group B and monochromatic images with energy levels ≥60 keV in Group A.In addition,filtered back-projection （FBP） reconstruction was used for monochromatic images 〈60 keV in Group A.The total radiation dose,total iodine load,contrast injection speed,and maximum injection pressure were compared between the two groups.The 40 keV and 60 keV spectral CT images of Group A were compared with the images of Group B to evaluate overall image quality.Results：The total radiation dose,total iodine load,injection speed,and maximum injection pressure for Group A were decreased by 19%,15%,34.4%,and 18.3%,respectively.The optimal energy level in spectral CT for displaying the abdominal vessels was 40 keV.At this level,the CT values in the abdominal aorta and its three branches,the portal vein and its two branches,and the inferior vena cava were all greater than 340 hounsfield unit （HU）.The abdominal organs of Groups A and B had similar degrees of absolute and relative enhancement （t =0.36 and-1.716 for liver,0.153 and-1.546 for pancreas,and 2.427 and 0.866 for renal cortex,all P 〉 0.05）.Signal-to-noise ratio of the abdominal organs was significantly lower in Group A than in Group B （t =-8.11 for liver,-7.83 for pancreas,and-5.38 for renal cortex,all P 〈 0.05）.However,the subjective scores for the 40 keV （FBP） and 60 keV （40% ASiR） spectral CT images determined by two radiologists were all 〉3,indicating clinically acceptable image quality.Conclusions：Single-phase,dual-energy spectral CT used for children with solid abdominal tumors can reduce contrast dose and radiation dose and can also maintain clinically acceptable image quality.

Measurement of radiation dose at the north interaction point of BEPC Ⅱ

The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI（T1） detector.

EFFECT OF IRRADIATION TEMPERATURE ON GENERAL EQUATION OF SOL FRACTION-DOSE RELATIONSHIP FOR FLUOROPOLYMERS

In this paper, the effect of irradiation temperature on sol fraction-dose relationship of tluoropolymers was studied. It was found that the increasing of irradiation temperature can result in the decreasing of β value of fluoropolymer, which increases the crosslinking probability of fluoropolymer. The relationship between crosslinking parameter β and irradiation temperature (T_i)of fluoropolymer is established as follows:β=2.2×10^(-3) T_g+4×10^(-4)(T_g-T_i)+0.206.values of some tluoropolymers calculated from the above expression are in agreement with the experimental values.

A multi-provincial survey and analysis of radiation doses from pediatric CT in China

Objective:To survey and analyze the radiation doses of pediatric CT in some provinces(autonomous region)or municipalities in China,and compare them with the data released by the relevant domestic and international organizations,so as to identify the current status of Chinese pediatric CT radiation doses.Methods:Radiation doses of pediatric CT were collected during August and December 2016 from 40 hospitals(including 18 children’s hospitals)in 15 provinces,municipalities or autonomous regions across the China.The procedures of head CT,chest CT and abdomen CT were selected in these hospitals,and 10 patients in each group of 0-<1 y,1-<5 y,5-<10 y and 10-<15 y were collected at random for every procedure.Weighted CT dose index(CTDI_(w)),volumetric CT dose index(CTDI_(vol))and dose length product(DLP)were used as survey quantities.An independent sample Kruskal-Wallis rank sum test was performed for CTDI and DLP for each procedure for different age groups,and pairwise comparisons were performed for intra-group data.The same statistical method was also conducted for CTDI and DLP of the same procedure and age group in different provinces or municipalities.Results:The 75th percentiles of the distribution of CTDI and DLP in different age groups of 0-<1 y,1-<5 y,5-<10 y and 10-<15 y were as follows:36.5,43.4,49.1,51.1 mGy and 488,635,723,852 mGy.cm for head,6.1,6.4,6.8,9.6 mGy and 108,136,187,293 mGy.cm for chest,10.5,10.3,11.4,13.0 mGy and 251,284,353,523 mGy.cm for abdomen.The 50th percentiles of the distribution of the radiation doses for the same procedure varied with the ages(head,CTDI_(w):H=155.66,DLP:H=212.35,P<0.05;chest,CTDI_(vol):H=85.43,DLP:H=197.36,P<0.05;abdomen:H=62.29,DLP:H=173.22,P<0.05)and with lower dose at lower age.Radiation doses were close for head between 5-<10 y and 10-<15 y groups,for chest between 1-<5 y and 5-<10 y groups and between 5-<10 y and 10-<15 y groups,and for abdomen between 0-<1 y and 1-<5 y groups,with no statistically significant difference(the adjusted P>0.05).The dose levels of different provinces or municipalities in the same procedure and age group were not consistent,and the differences were statistically significant(P<0.05).The data were different from the domestic and international values of DRL.The 75th percentiles of CTDI_(w) and DLP values of head CT were close to the data from Japan and UK(United Kingdom),higher than the data from Korea and EC(European Commission).The 75th percentiles of CTDI values of all age groups were lower than the values of Japan and UK,and larger than that of Korea and EC in chest CT and abdomen CT.Conclusions:The 75th percentile values of the distribution of the pediatric CT doses obtained from the survey were inconsistent with those released by the relevant national and international organizations.It is necessary to update the national DRLs for pediatric CT on the basis of the actual survey data.

Experimental measurement of radiation dose in a dedicated breast CT system

Radiation dose is an important performance indicator of a dedicated breast CT（DBCT）.In this paper,the method of putting thermoluminescent dosimeters（TLD） into a breast shaped PMMA phantom to study the dose distribution in breasts was improved by using smaller TLDs and a new half-ellipsoid PMMA phantom.Then the weighted CT dose index（CTDI_w） was introduced to average glandular assessment in DBCT for the first time and two measurement modes were proposed for different sizes of breasts.The dose deviations caused by using cylindrical phantoms were simulated using the Monte Carlo method and a set of correction factors were calculated.The results of the confirmatory measurement with a cylindrical phantom（11 cm/8 cm） show that CTDI_w gives a relatively conservative overestimate of the average glandular dose comparing to the results of Monte Carlo simulation and TLDs measurement.But with better practicability and stability,the CTDI_w is suitable for dose evaluations in daily clinical practice.Both of the TLDs and CTDI_w measurements demonstrate that the radiation dose of our DBCT system is lower than conventional two-view mammography.