Application of Monte Carlo simulation in radiation dose estimation and optimization for diagnostic radiology / 中华放射医学与防护杂志

The increasing frequency of radiographic diagnostic imaging and the cumulative dose to the public from radiation has raised widespread concerns. However, accurate measurement of the radiation dose received by the human body is difficult to achieve. Monte Carlo simulation, as a numerical computational method guided by probability statistics theory, has been applied to various dose assessments, imaging optimizations, and radiation protection in radiographic diagnostic imaging. We provide a comprehensive review of the principles of the Monte Carlo method, the modelling process of Monte Carlo simulation and the progress of its application to diagnostic radiological dose estimation.

The necessity and countermeasures of strengthening radiation dose management in diagnostic radiology / 中华放射医学与防护杂志

In recent years, the diagnostic radiology, especially CT scanning, has a rapidly increased frequency in our country, becoming the largest artificial radiation source to the average individual doses to the population. In clinical diagnosis and treatment activities, the examined patients and individuals may undergo multiple procedures and multiple frequencies of medical imaging in a short period of time and receive high cumulative radiation doses even exceeding 50 or 100 mSv in a single day, posing a potential risk to their health. Therefore, it is necessary to carry out statistical analysis and management of diagnostic radiation dose information to minimize the probability of excessive dose and associated radiation risk. In this paper, the international cognition of radiation risks in diagnostic radiology, diagnostic equipment and medical imaging frequency, radiation dose and its management status are described. Four countermeasures for radiation dose management are put forward to provide reference for further improving radiation protection in clinical practice.

Two Cases of Hypovascular Pituitary Metastases and Literature Review / 中国医学科学院学报

Pituitary metastasis,a rare kind of intracranial malignant tumor,is characterized by metastasis from all parts of the body to the pituitary.The common tumors metastatic to pituitary are abundant with blood supply,located in the posterior pituitary lobe and/or the pituitary stalk.The lesion shows infiltrative growth,and mainly demonstrates low signal on T1 weighted imaging and high signal on T2 weighted imaging.It is usually enhanced significantly after iodinated contrast administration.The metastatic tumor with poor blood supply is similar to pituitary macroadenoma on magnetic resonance image,which makes it difficult to be differentiated.We reported two cases of pathologically diagnosed pituitary metastasis with poor blood supply and reviewed related papers,aiming to provide the imaging differentiation points of hypovascular pituitary metastasis.

Management scheme for infection control and radiological protection in diagnostic radiology examination of novel coronavirus pneumonia / 中华放射医学与防护杂志

Since the epidemic of novel coronavirus pneumonia broke out, diagnostic imaging was providing valuable radiological support for disease diagnosis and progress evaluation. Radiological staff, especially radiographers were staying at the front line of epidemic prevention and control. They were facing the patients directly with dual responsibility and pressure of infection control protection and radiation protection. A number of relevant professional experts established the consensus which clarified three parts of detailed implementing rules including infection control and protection of the radiological staff, disinfection of diagnostic radiology equipment and place, radiological protection. The aim was to further standardize the clinical procedures of radiological staff, reduce the infection risk and the radiation risk of medical staff and patients.

Study of nursing guidance on improving the radiation protection effect of accompanying examiners in CT examination / 中华放射医学与防护杂志

Objective@#To survey the current situation of wearing protective articles by accompanying examiners in the nursing conditions of intervention and non-intervention during CT diagnosis in a tertiary A hospital.@*Methods@#A control group and an intervention group were set up to investigate the situation of wearing protective devices. Attempt was made to use mobile lead screens in place of personal protective devices and their effects were investigated.@*Results@#A total of 4 890 unavoidable accompanying examiners wearing protective equipment during CT examination were investigated. After nursing guidance, the wearing rate increased from 73% to 94%, and the complete wearing rate increased from 19% to 81%. Refusal to wear protective devices was mostly due to limited time. Refusal rate of emergency accompanying examiners was significantly higher than that of outpatient and inpatient accompanying examiners. After using mobile lead screen, the probability of personnel protection increased to 99%.@*Conclusions@#Nursing intervention can effectively improve the wearing rate and complete wearing rate of protective articles for accompanying examiners. Moving glass lead screen is conducive to the improvement of protection level for accompanying examiners..

Study on estimation of medical exposure frequency in China / 中华放射医学与防护杂志

Objective To study the estimation method of medical exposure frequency in China through the survey of diagnostic radiology and radiotherapy institutions in selected provinces.Methods A survey of medical exposure frequency was carried out involving 557 diagnostic radiology and radiotherapy institutions in 25 provinces.The correlation analysis and multiple linear regression analysis were conducted,with the fitting effects of the models with different variables being compared.Results The total medical exposure frequencies highly correlated with number of outpatient,number of equipment and number of radiation workers (| r| ＞0.5).Representative samples of the daily medical exposure workload were obtained by stratified random sampling from the survey data.Mathematical models were built using the multiple linear regression between total medical exposure frequency and hospital levels,number of outpatients,number of inpatients,number of equipment,and number of radiation workers.The total medical exposure frequency in 2016 was estimated to be 589 million examinations based on the models.In addition,the frequencies of medical procedures were derived using the robust regression and the median regression.Conclusions There are several methods for estimating the total medical exposure frequency.It is desirable to use the stratified random sampling combined with the published statistical and monitoring data.The representativeness of sample is critical.The specification and optimization of models also require further study.

Survey on frequency of medical X-ray diagnosis in Guangdong province / 中华放射医学与防护杂志

Objective To obtain the information on the frequency of diagnostic X-ray examinations in Guangdong province in order to provide reference data for the rational application of diagnostic radiology.Methods A typical stratified sampling method was used to select 56 medical institutions in 7 districts in Guangdong province for the survey of the frequencies of diagnostic X-ray examinations.Multiple linear regression analysis was performed using the relevant variables of the surveyed sample (total number of hospitals,number of outpatients,number of inpatients,number of radiation workers,and number of diagnostic equipment).The dependent independent variables were fitted to the linear regression equation to estimate the frequency of routine diagnostic X-ray examinations and diagnostic CT examinations and the total frequency of diagnostic medical X-ray examinations in Guangdong province in 2016.Results By the largest percentage contribution,chest radiography accounted for 60.84％ of the routine diagnostic X-ray examinations,brain scans 28.03％ of diagnostic CT examinations,and cardiovascular interventions 48.83％ of interventional radiology.For the group of above 40 years old,the largest percentage contributions were,respectively,routine diagnostic X-ray examination 47.95％,diagnostic CT examinations 65.41％,and interventional radiology 75.64％.All types of medical X-ray examinations are concentrated in the tertiary and secondary hospitals.Based on this survey,the examination frequencies for 2016 in Guangdong were estimated to be,respectively,diagnostic X-ray examination 699 examinations per 1 000 population and CT diagnostic 231 examinations per 1 000 population,with the total of 992 examinations per 1 000 population.Conclusions This survey was completed to a limited degree and less investment.The results showed that the diagnostic radiology in Guangdong province is developing with increased frequencies,with wide varieties of X-ray examination types in the tertiary and secondary hospitals.Relevant competent defpartments should pay attention to strengthening the radiation protection of examined individuals and actively providing guidance on the correct and rational applicc ation of diagnostic radiology so as to achieve profit and avoid disadvantages.

Study of nursing guidance on improving the radiation protection effect of accompanying examiners in CT examination / 中华放射医学与防护杂志

Objective To survey the current situation of wearing protective articles by accompanying examiners in the nursing conditions of intervention and non-intervention during CT diagnosis in a tertiary A hospital. Methods A control group and an intervention group were set up to investigate the situation of wearing protective devices. Attempt was made to use mobile lead screens in place of personal protective devices and their effects were investigated. Results A total of 4890 unavoidable accompanying examiners wearing protective equipment during CT examination were investigated. After nursing guidance, the wearing rate increased from 73％ to 94％, and the complete wearing rate increased from 19％ to 81％. Refusal to wear protective devices was mostly due to limited time. Refusal rate of emergency accompanying examiners was significantly higher than that of outpatient and inpatient accompanying examiners. After using mobile lead screen, the probability of personnel protection increased to 99％. Conclusions Nursing intervention can effectively improve the wearing rate and complete wearing rate of protective articles for accompanying examiners. Moving glass lead screen is conducive to the improvement of protection level for accompanying examiners..

Investigation and analysis of patient dose levels from diagnostic radiology in Beijing / 中华放射医学与防护杂志

Objective To investigate the radiation dose levels to the adults examined from diagnostic exposure in Beijing. Methods The radiation doses to the examined individuals were measured by using individual diagnostic radiology equipments in 30 random hospitals from a total of 10 districts and suburban areas, including 1 182 samples of X-ray photography,542 samples of mammography and 410 samples of CT examination. Results 2 134 samples were measured in this study. The dose ranges of X-ray photography, CR, and DR were 0?4 -24?1, 0?3 -13?9 and 0?1 -15?9 mGy, respectively. The average dose range of glandular breast was 0?3-5?4 mGy. In 410 CT samples the value of CTDIw , CTDIvol and DLP were 28?1 - 96?3 mGy, 7?0 - 23?4 mGy, and 162?2 - 898?1 mGy·cm, respectively. Conclusions Several dose levels from diagnostic examination were higher than guidance level for medical exposure in GB 18871-2002,which should be noted.

Interpretation of Digital Chest Radiographs: Comparison of Light Emitting Diode versus Cold Cathode Fluorescent Lamp Backlit Monitors

OBJECTIVE: To compare the diagnostic performance of light emitting diode (LED) backlight monitors and cold cathode fluorescent lamp (CCFL) monitors for the interpretation of digital chest radiographs. MATERIALS AND METHODS: We selected 130 chest radiographs from health screening patients. The soft copy image data were randomly sorted and displayed on a 3.5 M LED (2560 x 1440 pixels) monitor and a 3 M CCFL (2048 x 1536 pixels) monitor. Eight radiologists rated their confidence in detecting nodules and abnormal interstitial lung markings (ILD). Low dose chest CT images were used as a reference standard. The performance of the monitor systems was assessed by analyzing 2080 observations and comparing them by multi-reader, multi-case receiver operating characteristic analysis. The observers reported visual fatigue and a sense of heat. Radiant heat and brightness of the monitors were measured. RESULTS: Measured brightness was 291 cd/m2 for the LED and 354 cd/m2 for the CCFL monitor. Area under curves for nodule detection were 0.721 +/- 0.072 and 0.764 +/- 0.098 for LED and CCFL (p = 0.173), whereas those for ILD were 0.871 +/- 0.073 and 0.844 +/- 0.068 (p = 0.145), respectively. There were no significant differences in interpretation time (p = 0.446) or fatigue score (p = 0.102) between the two monitors. Sense of heat was lower for the LED monitor (p = 0.024). The temperature elevation was 6.7degrees C for LED and 12.4degrees C for the CCFL monitor. CONCLUSION: Although the LED monitor had lower maximum brightness compared with the CCFL monitor, soft copy reading of the digital chest radiographs on LED and CCFL showed no difference in terms of diagnostic performance. In addition, LED emitted less heat.

Comparison of Transaxial Source Images and 3-Plane, Thin-Slab Maximal Intensity Projection Images for the Diagnosis of Coronary Artery Stenosis with Using ECG-Gated Cardiac CT

OBJECTIVE: We wanted to compare the transaxial source images with the optimized three plane, thin-slab maximum intensity projection (MIP) images from electrocardiographic (ECG)-gated cardiac CT for their ability to detect hemodynamically significant stenosis (HSS), and we did this by means of performing a receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: Twenty-eight patients with a heart rate less than 66 beats per minute and who were undergoing both retrospective ECG-gated cardiac CT and conventional coronary angiography were included in this study. The contrast-enhanced CT scans were obtained with a collimation of 16x0.75-mm and a rotation time of 420 msec. The transaxial images were reconstructed at the mid-diastolic phase with a 1-mm slice thickness and a 0.5-mm increment. Using the transaxial images, the slab MIP images were created with a 4-mm thickness and a 2-mm increment, and they covered the entire heart in the horizontal long axis (4 chamber view), in the vertical long axis (2 chamber view) and in the short axis. The transaxial images and MIP images were independently evaluated for their ability to detect HSS. Conventional coronary angiograms of the same study group served as the standard of reference. Four radiologists were requested to rank each image with using a five-point scale (1 = definitely negative, 2 = probably negative, 3 = indeterminate, 4 = probably positive, and 5 = definitely positive) for the presence of HSS; the data were then interpreted using ROC analysis. RESULTS: There was no statistical difference in the area under the ROC curve between transaxial images and MIP images for the detection of HSS (0.8375 and 0.8708, respectively; p > 0.05). The mean reading time for the transaxial source images and the MIP images was 116 and 126.5 minutes, respectively. CONCLUSION: The diagnostic performance of the MIP images for detecting HSS of the coronary arteries is acceptable and this technique's ability to detect HSS is comparable to that of the transaxial source images.

The application of the diagnostic radiology in Ear Nose Throat field

The application of the diagnostic radiology and interventional radiology (I.R) is more and more popular all over the world. In Vietnam the I.R was first applicated at Bach Mai Hospital (Ha Noi) 1991 and Cho Ray Hospital in 1999, I.R has been used widely in many medical fields also in E.N.T (treatment of severe epistaxis and naso-angiofibroma). The authors report two typical severe epistaxis cases which treated by I.R at E.N.T department Cho Ray Hospital. The authors dertermined DSA was a very good mean that could help to evaluate and intervent for the injury of the vein, reduced the mininum ratio of severe naso-angiofibroma

Receiver Operating Characteristic (ROC) Curve: Practical Review for Radiologists

The receiver operating characteristic (ROC) curve, which is defined as a plot of test sensitivity as the y coordinate versus its 1-specificity or false positive rate (FPR) as the x coordinate, is an effective method of evaluating the performance of diagnostic tests. The purpose of this article is to provide a nonmathematical introduction to ROC analysis. Important concepts involved in the correct use and interpretation of this analysis, such as smooth and empirical ROC curves, parametric and nonparametric methods, the area under the ROC curve and its 95% confidence interval, the sensitivity at a particular FPR, and the use of a partial area under the ROC curve are discussed. Various considerations concerning the collection of data in radiological ROC studies are briefly discussed. An introduction to the software frequently used for performing ROC analyses is also presented.

Performance of Computer-aided Detection in False-Negative Screening Mammograms of Breast Cancers

PURPOSE: To analyze retrospectively the abnormalities visible on the false-negative screening mammograms of patients with breast cancer and to determine the performance of computer-aided detection (CAD) in the detection of cancers. MATERIALS AND METHODS: Of 108 consecutive cases of breast cancer diagnosed over a period of 6 years, of which previous screening mammograms were available, 32 retrospectively visible abnormalities (at which locations cancer later developed) were found in the previous mammograms, and which were originally reported as negative. These 32 patients ranged in age from 38 to 72 years (mean 52 years). We analyzed their previous mammographic findings, and assessed the ability of CAD to mark cancers in previous mammograms, according to the clinical presentation, the type of abnormalities and the mammographic parenchymal density. RESULTS: In these 32 previous mammograms of breast cancers (20 asymptomatic, 12 symptomatic), the retrospectively visible abnormalities were identified as densities in 22, calcifications in 8, and densities with calcifications in 2. CAD marked abnormalities in 20 (63%) of the 32 cancers with false-negative screening mammograms; 14 (70%) of the 20 subsequent screening-detected cancers, 5 (50%) of the 10 interval cancers, and 1 (50%) of the 2 cancers palpable after the screening interval. CAD marked 12 (50%) of the 24 densities and 9 (90%) of the 10 calcifications. CAD marked abnormalities in 7 (50%) of the 14 predominantly fatty breasts, and 13 (72%) of the 18 dense breasts. CONCLUSION: CAD-assisted diagnosis could potentially decrease the number of false-negative mammograms caused by the failure to recognize the cancer in the screening program, although its usefulness in the prevention of interval cancers appears to be limited.

Total Quality Control Management in Diagnostic Radiology Division / 医疗卫生装备

The methods and experience in total quality control in radiology division are discussed including classified management & separated responsibility system,the program of control,system of job responsibility,overall management for all staff,self-control of staff,etc,which improve the quality of the sections so that departments and economic credibility effectiveness increase dramatically.

Liquid-Crystal Display Monitors and Cathode-Ray Tube Monitors: A Comparison of Observer Performance in the Detection of Small Solitary Pulmonary Nodules

OBJECTIVE: To compare observer performance using liquid-crystal display (LCD) and cathode-ray tube (CRT) monitors in the interpretation of soft-copy chest radiographs for the detection of small solitary pulmonary nodules. MATERIALS AND METHODS: By reviewing our Medical Center's radiologic information system, the eight radiologists participating in this study (three board-certified and five resident) retrospectively collected 40 chest radiographs showing a solitary noncalcified pulmonary nodule approximately 1 cm in diameter, and 40 normal chest radiographs. All were obtained using a storage-phosphor system, and CT scans of the same patients served as the gold standard for the presence of a pulmonary nodule. Digital images were displayed on both high-resolution LCD and CRT monitors. The readers were requested to rank each image using a five point scale (1 = definitely negative, 3 = equivocal or indeterminate, 5 = definitely positive), and the data were interpreted using receiver operating characteristic (ROC) analysis. RESULTS: The mean area under the ROC curve was 0.8901+/-0.0259 for the LCD session, and 0.8716+/-0.0266 for the CRT session (p > 0.05). The reading time for the LCD session was not significantly different from that for the CRT session (37.12 and 41.46 minutes, respectively; p = 0.889). CONCLUSION: For detecting small solitary pulmonary nodules, an LCD monitor and a CRT monitor are comparable.

Percutaneous Fine Needle Aspiration Biopsy for the Intrathoracic Lesions: What is the Meaning of Non-Diagnostic Results?

PURPOSE: To know what is the meaning of non-diagnostic results of fine needle aspiration biopsy (FNAB) and whether repeated aspiration is needed or not in those situations. MATERIALS AND METHODS: We reviewed 1845 patients who underwent FNAB from 1997 to 2001. Non-diagnostic results of the first FNAB were divided into four groups: insufficient number of cells, inflammatory cells, necrotic debris and atypical cells. We analyzed final diagnosis of 531 patients who had non-diagnostic results from the first FNAB. Among them, 207 lesions were re-biopsied because of clinical and radiologic suspicion of malignancy. The diagnostic yield of repeated FNAB was analyzed and compared with the results of the first FNAB. RESULTS: Among 255 cases with "inflammatory cells only" results, 120 cases were confirmed benignancy on follow-up. Twenty nine of 50 atypical cells (58%) were malignant on follow-up. One hundred one of 207 repeated FNAB resulted in the non-diagnostic reports, and 106 of 207 repeated FNAB were diagnosed as specific diagnosis. Among thirty lesions showing atypical cells on the repeated FNAB, 22 (73%) were identified as malignant neoplasms. CONCLUSION: When the specimen of FNAB shows atypical cells, the possibility of malignancy is very high. When the results of FNAB is non-diagnostic in the cases with clinical and radiological suspicion of malignancy, repeated FNAB procedures should be seriously considered and will be helpful for accurate specific diagnosis.

The Diagnosis of Small Solitary Pulmonary Nodule: Comparison of Standard and Inverse Digital Images on a High-Resolution Monitor using ROC Analysis

PURPOSE: To study the impact of inversion of soft-copy chest radiographs on the detection of small solitary pulmonary nodules using a high-resolution monitor. MATERIALS AND METHODS: The study group consisted of 80 patients who had undergone posterior chest radiography; 40 had a solitary noncalcified pulmonary nodule approximately 1 cm in diameter, and 40 were control subjects. Standard and inverse digital images using the inversion tool on a PACS system were displayed on high-resolution monitors (2048x2560x8 bit). Ten radiologists were requested to rank each image using a five-point scale (1=definitely negative, 3=equivocal or indeterminate, 5=definite nodule), and the data were interpreted using receiver operating characteristic (ROC) analysis. RESULTS: The area under the ROC curve for pooled data of standard image sets was significantly larger than that of inverse image sets (0.8893 and 0.8095, respectively; p0.05). CONCLUSION: For detecting small solitary pulmonary nodules, inverse digital images were significantly inferior to standard digital images.

A Study on Improvement of Curriculum in Diagnostic Radiology / 한국의학교육

The purposes of this study were to survey the present state and problems related to curriculum and clinical clerkship of diagnostic radiology and to find out alternatives for the improvement of curriculum design in diagnostic radiology. The results of this study are as following: First, 43.3% out of professors, 70.6% out of residents and 69.4% out of students reply that they don't attain the objectives of classwork, although they finish all their classwork successfully. Second, most of them reply that classwork is oriented by professors and least participated in by students. Third, PBL(Problem-based Learning) by small group is very effective to learning. Fourth, the reasons why clinical clerkship isn't systematic are that there aren't professors-in-charge of clinical clerkship and that the schedule of clinical clerkship is irregular. Fifth, students' participation in clinical clerkship is not substantial participation, such as interpretation and procedure, but simple observation. Based on these results the points which the improvement is called for are as follows: First, professors must achieve the objectives of classwork by thorough analysis on those within limited class hours. Second, it is desirable that they apply learning methods to improve students' thinking by small group activities to their classwork. Third, professors-in-charge of clinical clerkship are surely needed.

High-Resolution PACS Work station: Diagnostic Performance and Comparison with Laser-Printed CR Films in Chest Diseases

OBJECTIVES: To compare the diagnostic performance of a high-resolution picture archiving and communications system (PACS) workstation directly interfaced with computed radiography(CR) with laser-printed CR films in chest diseases. MATERIALS AND METHODS: Chest radiographs with (n=91) and without (n=25) abnormalities were included. Atotal of 100 abnormalities from 91 radiographs consisted of irregular lines, pneumothoraces, nodules and consolidations (25 of each). Laser-printed hard copies with dynamic range compression (DRC) were produced. InPACS, soft copies of 1760 X 2140 X 10 bits CR images were displayed on 1536 X 2048 with 8 bit gray-scale monitors.The performance of four observers was compared between laser-printed hard copies and CR images displayed on a workstation according to receiver operating characteristic analysis. RESULTS: Overall, no significant difference sin observer performance were observed between laser-printed hard copies and CR images displayed on a workstation(p=.2454). Even though statistically not significant, the former was slightly superior to the latter for lesions of irregular lines, pneumothoraces, and consolidations, whereas for nodules, the latter was slightly better than the former. CONCLUSION: The diagnostic performance of a high-resolution PACS workstation in chest radiographs is acceptable and comparable to CR hard copies printed with DRC processing mode.