Assessment of changes in vessel area during needle manipulation in microvascular anastomosis using a deep learning-based semantic segmentation algorithm: A pilot study.

Appropriate needle manipulation to avoid abrupt deformation of fragile vessels is a critical determinant of the success of microvascular anastomosis. However, no study has yet evaluated the area changes in surgical objects using surgical videos. The present study therefore aimed to develop a deep learning-based semantic segmentation algorithm to assess the area change of vessels during microvascular anastomosis for objective surgical skill assessment with regard to the "respect for tissue." The semantic segmentation algorithm was trained based on a ResNet-50 network using microvascular end-to-side anastomosis training videos with artificial blood vessels. Using the created model, video parameters during a single stitch completion task, including the coefficient of variation of vessel area (CV-VA), relative change in vessel area per unit time (ΔVA), and the number of tissue deformation errors (TDE), as defined by a ΔVA threshold, were compared between expert and novice surgeons. A high validation accuracy (99.1%) and Intersection over Union (0.93) were obtained for the auto-segmentation model. During the single-stitch task, the expert surgeons displayed lower values of CV-VA (p < 0.05) and ΔVA (p < 0.05). Additionally, experts committed significantly fewer TDEs than novices (p < 0.05), and completed the task in a shorter time (p < 0.01). Receiver operating curve analyses indicated relatively strong discriminative capabilities for each video parameter and task completion time, while the combined use of the task completion time and video parameters demonstrated complete discriminative power between experts and novices. In conclusion, the assessment of changes in the vessel area during microvascular anastomosis using a deep learning-based semantic segmentation algorithm is presented as a novel concept for evaluating microsurgical performance. This will be useful in future computer-aided devices to enhance surgical education and patient safety.

[Attempt to Evaluate the Influence of Morphology, Blood Flow, and Hardness in Mammary Gland Malignant Disease].

It is important to make an appropriate diagnosis category by evaluating the morphology, blood flow, and hardness of mammary gland disease in breast ultrasound, such as screening and detailed examination. Therefore, understanding the characteristics and effects of B-mode (BM), color Doppler (CD), and elastography (EG) in ultrasonography is considered to lead to improvement in examination accuracy. In this study, we clarified the impact of each function on qualitative diagnosis, with the aim of assisting technologists with high-accuracy breast ultrasound. The subjects were 531 malignant tumor cases. The final evaluation of ultrasonography was classified into 5 levels, BM was classified into 5 levels, CD was classified into 4 levels based on blood flow evaluation, and EG was classified into 9 levels based on the Tsukuba elasticity score. The contribution rates of BM, CD, and EG were 70.4%, 15.0%, and 14.6% in all cases (correlation ratio 0.87). BM was most important at the time of breast ultrasound. No difference was observed between CD and EG. In the evaluation by malignant tumor, each characteristic was seen in the degree of influence. It became clear that comprehensive evaluation is important for benign/malignant evaluation and histological-type estimation.

Tissue Acceleration as a Novel Metric for Surgical Performance During Carotid Endarterectomy.

BACKGROUND AND OBJECTIVES: Gentle tissue handling to avoid excessive motion of affected fragile vessels during surgical dissection is essential for both surgeon proficiency and patient safety during carotid endarterectomy (CEA). However, a void remains in the quantification of these aspects during surgery. The video-based measurement of tissue acceleration is presented as a novel metric for the objective assessment of surgical performance. This study aimed to evaluate whether such metrics correlate with both surgeons' skill proficiency and adverse events during CEA. METHODS: In a retrospective study including 117 patients who underwent CEA, acceleration of the carotid artery was measured during exposure through a video-based analysis. Tissue acceleration values and threshold violation error frequencies were analyzed and compared among the surgeon groups with different surgical experience (3 groups: novice , intermediate , and expert ). Multiple patient-related variables, surgeon groups, and video-based surgical performance parameters were compared between the patients with and without adverse events during CEA. RESULTS: Eleven patients (9.4%) experienced adverse events after CEA, and the rate of adverse events significantly correlated with the surgeon group. The mean maximum tissue acceleration and number of errors during surgical tasks significantly decreased from novice, to intermediate, to expert surgeons, and stepwise discriminant analysis showed that the combined use of surgical performance factors could accurately discriminate between surgeon groups. The multivariate logistic regression analysis revealed that the number of errors and vulnerable carotid plaques were associated with adverse events. CONCLUSION: Tissue acceleration profiles can be a novel metric for the objective assessment of surgical performance and the prediction of adverse events during surgery. Thus, this concept can be introduced into futuristic computer-aided surgeries for both surgical education and patient safety.

Validation of the Japanese version of the Body Image Scale for bladder cancer patients.

The Body Image Scale (BIS) is a 10-item tool that measures the body images of cancer patients. This study aims to validate the Japanese version of the BIS for bladder cancer patients. A multicenter cross-sectional survey was used to identify the participants, which included Japanese bladder cancer patients. The percentage of missing responses, internal consistency, and known-group validity were evaluated. The correlations between the BIS and two HRQOL instruments (the Bladder Cancer Index and the SF-12) were assessed to determine convergent validity. Among 397 patients, 221 patients were treated by transurethral resection of bladder tumor (TURBT) endoscopically, 49 patients underwent cystectomy with neobladder, and 127 patients underwent cystectomy involving stoma. The percentage of missing responses in the BIS ranged from 8.1 to 15.6%. Cronbach's α coefficient was 0.924. Higher BIS scores indicate negative body image, and the median BIS score for patients with native bladders after TURBT (0.5) was significantly lower than those of the patients with neobladder (4.0) and stoma formation (7.0), which indicated the discriminatory ability of the BIS. Each domain of the Bladder Cancer Index and the role summary score of the SF-12 correlated to the BIS scores, which confirmed the convergent validity. A range of BIS scores were identified among patients who reported similar physical summary scores and mental summary scores of the SF-12. This study confirmed the reliability and validity of the Japanese version of the BIS for bladder cancer patients.

The health economic effects of an imaging technology-based telemedicine system for rural neuro-emergency patient care.

OBJECTIVE: "Join," an imaging technology-based telemedicine system, allows simultaneous radiological information sharing between physically remote institutions, virtually connecting advanced medical institutions and rural hospitals. This study aimed to elucidate the health economics effect of Join for neurological telemedicine in rural areas in Hokkaido, Japan. METHODS: Information concerning 189 requests for patient transfer from Furano Kyokai Hospital, a regional rural hospital, to Asahikawa Medical University Hospital (AMUH), an advanced academic medical institution, was retrospectively collected. The Join system was established between Furano Kyokai Hospital and AMUH in February 2019. Data collected from patients between April 2017 and December 2018 were included in the non-Join group, and those collected between February 2019 and October 2020 were included in the Join group. Clinical variables, reasons for patient transfer requests, duration of hospital stay, and medical costs per patient were analyzed between these two groups. Furthermore, clinical characteristics were compared between patients who were transferred and not transferred based on Join. RESULTS: More patients were discharged < 7 days after transfer to AMUH in the non-Join group compared with the Join group (p = 0.02). When focusing on the Join group, more patients who were not transferred were discharged < 1 week (p < 0.01). On the other hand, more patients required surgery (p = 0.01) when transferred. The ratio of patients whose medical cost was < USD5000 substantially decreased, from 33% for the non-Join group to 13% for the Join group. CONCLUSIONS: An imaging technology-based telemedicine system, Join, contributed to reducing unnecessary neuro-emergency patient transfer in a remote rural area, and telemedicine with an integrated smartphone system allowed medical personnel to effectively triage at a distance neuro-emergency patients requiring advanced tertiary care.

Cost-effectiveness analysis using lifetime attributable risk of proton beam therapy for pediatric medulloblastoma in Japan.

Compared to conventional X-ray therapy, proton beam therapy (PBT) has more clinical and physical advantages such as irradiation dose reduction to normal tissues for pediatric medulloblastoma. However, PBT is expensive. We aimed to compare the cost-effectiveness of PBT for pediatric medulloblastoma with that of conventional X-ray therapy, while focusing on radiation-induced secondary cancers, which are rare, serious and negatively affect a patient's quality of life (QOL). Based on a systematic review, a decision tree model was used for the cost-effectiveness analysis. This analysis was performed from the perspective of health care payers; the cost was estimated from medical fees. The target population was pediatric patients with medulloblastoma below 14 years old. The time horizon was set at 7.7 years after medulloblastoma treatment. The primary outcome was the incremental cost-effectiveness ratio (ICER), which was defined as the ratio of the difference in cost and lifetime attributable risk (LAR) between conventional X-ray therapy and PBT. The discount rate was set at 2% annually. Sensitivity analyses were performed to model uncertainty. Cost and LAR in conventional X-ray therapy and PBT were Japanese yen (JPY) 1 067 608 and JPY 2436061 and 42% and 7%, respectively. The ICER was JPY 3856398/LAR. In conclusion, PBT is more cost-effective than conventional X-ray therapy in reducing the risk of radiation-induced secondary cancers in pediatric medulloblastoma. Thus, our constructed ICER using LAR is one of the valid indicators for cost-effectiveness analysis in radiation-induced secondary cancer.

[Investigation of Preferences in Working Environment of Students for Maintaining Uniform Geographical Distribution of Radiological Technologists].

PURPOSE: This study was designed to assess working environment preferences of students in the Department of Radiological Technology using conjoint analysis for establishing an efficient medical system. METHOD: We carried a questionnaire survey on working environment preferences for 196 students in the Department of Radiological Technology in Japan. We defined eight characteristics for virtual medical facilities as follows: presence of colleagues who can be consulted, employment status, number of night shift per month, academic meeting participation, number of hospital beds, possession of nuclear medicine imaging systems and radiation therapy systems, location of medical facilities, and change rate in annual income. A total of 18 virtual medical facilities were selected by an orthogonal array table using above-mentioned characteristics. The acquired data by the pairwise comparison method were analyzed by conjoint analysis. Marginal rates of substitution that represent students' preferences were also calculated. RESULT: The factors that influenced their preferences were the following: placement of medical facilities in great city, presence of colleagues who can be consulted, employment status is not non-regular employment, set up of nuclear medicine imaging systems and radiation therapy systems, the number of night shift is twice per month, and attendances at academic meetings. CONCLUSION: In summary, students in the Department of Radiological Technology tend to prefer the facilities with regular employment, great city, presence of colleagues who can be consulted, and possession of nuclear medicine imaging systems and/or radiation therapy systems.

Mediating Factors Between Parental Socioeconomic Status and Small for Gestational Age in Infants: Results from the Hokkaido Study on Environment and Children's Health.

OBJECTIVES: Previous studies indicated a significant association between small for gestational age (SGA) in infants and their parents' socioeconomic status (SES). Thus, this study aimed to examine if parental factors, such as maternal smoking, and the pre-pregnancy body mass index (BMI) could mediate the associations between parental SES and SGA. METHODS: The participants of this study were pregnant women who enrolled in an ongoing birth cohort study, the Hokkaido study, during the first trimester of their pregnancies. A total of 14,593 live singleton births were included in the statistical analysis, of which 1011 (6.9%) were SGA. Two structural equation models were employed to evaluate the associations between parental SES, parental characteristics, and SGA. RESULTS: The effect of low SES on SGA was directly mediated by maternal pre-pregnancy BMI, smoking during the third trimester, and alcohol consumption during the first trimester in the first model, which was based the assumption of independent associations between mediating factors. In the second model, which additionally considered the mediating factors from the first model, smoking during pregnancy mediated decline in parental SES, consequently increased SGA. Moreover, an increase in pregnancy smoking status increased the prevalence of lower maternal pre-pregnancy BMI and its effect on SGA. CONCLUSIONS FOR PRACTICE: In this study, we observed the independent mediating effect of maternal pre-pregnancy BMI, smoking, and alcohol consumption during pregnancy on low SES and, consequently, SGA, with the additional mediating pathway of SES to smoking to low BMI on SGA.

A Bayesian Network-Based Browsing Model for Patients Seeking Radiology-Related Information on Hospital Websites: Development and Usability Study.

BACKGROUND: An increasing number of people are visiting hospital websites to seek better services and treatments compared to the past. It is therefore important for hospitals to develop websites to meet the needs of their patients. However, few studies have investigated whether and how the current hospital websites meet the patient's needs. Above all, in radiation departments, it may be difficult for patients to obtain the desired information regarding modality and diagnosis because such information is subdivided when described on a website. OBJECTIVE: The purpose of this study is to suggest a hospital website search behavior model by analyzing the browsing behavior model using a Bayesian network from the perspective of one-to-one marketing. METHODS: First, we followed the website access log of Hokkaido University Hospital, which was collected from September 1, 2016, to August 31, 2017, and analyzed the access log using Google Analytics. Second, we specified the access records related to radiology from visitor browsing pages and keywords. Third, using these resources, we structured 3 Bayesian network models based on specific patient needs: radiotherapy, nuclear medicine examination, and radiological diagnosis. Analyzing each model, this study considered why some visitors could not reach their desired page and improvements to meet the needs of visitors seeking radiology-related information. RESULTS: The radiotherapy model showed that 74% (67/90) of the target visitors could reach their requested page, but only 2% (2/90) could reach the Center page where inspection information, one of their requested pages, is posted. By analyzing the behavior of the visitors, we clarified that connecting with the radiotherapy and radiological diagnosis pages is useful for increasing the proportion of patients reaching their requested page. CONCLUSIONS: We proposed solutions for patient web-browsing accessibility based on a Bayesian network. Further analysis is necessary to verify the accuracy of the proposed model in comparison to other models. It is expected that information provided on hospital websites will be improved using this method.

Comparison of Health-Related Quality of Life Between Japanese and American Patients with Bladder Cancer as Measured by a Newly Developed Japanese Version of the Bladder Cancer Index.

INTRODUCTION: The aim of this study is to characterize health related quality of life (HRQOL) in Japanese patients after bladder cancer surgery and to perform cross-cultural comparison between Japanese and American patients. METHODS: Firstly, we cross-sectionally assessed HRQOL of 371 patients in Japan using the Bladder Cancer Index (BCI-Japanese). HRQOL of the four groups of patients (native bladder without intravesical therapy, native bladder with intravesicaltherapy, cystectomy with ileal conduit, and cystectomy with neobladder) were assessed. Secondly, we compared the Japanese with the American cohort (n = 315) from the original BCI paper. After adjusting for age and gender, the differences in each BCI subdomain score was analyzed. RESULTS: Among Japanese patients, the urinary domain function score was significantly lower among the cystectomy with neobladder group, compared to the cystectomy with ileal conduit group (p < 0. 01). Despite this, the urinary bother was comparable between the two groups. Although there were apparent differences between Japanese and American patients, there were few differences in Urinary and Bowel HRQOL. In three of the four treatment groups (other than native bladder with intravesical therapy), Japanese patients were more likely than Americans to report poor sexual function (p < 0.05). However, Japanese patients were less likely than Americans to be bothered by their lower sexual function, regardless of treatment (p < 0.05). CONCLUSIONS: HRQOL outcomes following treatment of bladder cancer in Japan are comparable to those in the USA, except for sexual functioning and sexual bother. The BCI can be used for cross-cultural assessments of HRQOL in bladder cancer patients.

Health-related quality of life in Japanese patients with bladder cancer measured by a newly developed Japanese version of the Bladder Cancer Index.

INTRODUCTION: We validated a Japanese version of the Bladder Cancer Index (BCI) as a tool for measuring health-related quality of life (HRQOL) in bladder cancer patients treated with various surgical procedures. METHODS: The reliability and validity of the Japanese BCI were examined in 397 Japanese patients with bladder cancer via cross-sectional analysis. The patients simultaneously completed the Short Form (SF)-12, EQ-5D, and the Functional Assessment of Cancer Therapy-General and Bladder (FACT-G and FACT-BL). The differences in BCI subscales among various treatment groups were analyzed. RESULTS: This study involved 397 patients (301 males and 96 females), with a mean age of 70 years and a median disease duration of 29 months (IQR: 12-66 months). Of these patients, 221 underwent transurethral resection of a bladder tumor, and 176 patients underwent radical cystectomy (ileal conduit: 101 patients, ileal neobladder: 49, and ureterostomy: 26). Cronbach's alpha coefficient was ≥ 0.78 for all subscales, except the bowel bother subscale. Despite moderate correlations being detected between the function and bother score in urinary and bowel domains, the sexual function score was inversely correlated with the sexual bother score (r = - 0.19). A missing value percentage of > 15% was associated with old age (p < 0.05). The mean domain scores differed significantly among distinct clinically relevant treatment groups. CONCLUSIONS: Although revisions are needed to make it easier for elderly patients to comprehend, we confirmed the reliability and validity of the Japanese BCI. The Japanese BCI could be used for cross-cultural assessments of HRQOL in bladder cancer patients.

[Assessing Visual Attention of Mammography Positioning Using Eye Tracking System: A Comparison between Experts and Novices].

A common cause for image retakes in mammography is lack of proper positioning. Image retake is a potential hazard of increased radiation exposure to patient, patient discomfort and pain. Therefore, a mammographer has to provide fast exams with fewer retakes. Although evaluation of how a mammographer is effectively positioning has been studied in many ways, little research has been conducted to analyze visual attention. In this study, eye tracking system was adopted to detect eye movements and locations within a participants' visual fields during positioning. Eye tracking system has been widely used for assessing technical skills and risk awareness, and for comparing the skills between experts and novices. Two skilled mammographers and two novices were recruited. Positioning related activities were divided into two phases: patient's observation and breast positioning. Breast positioning was sub-divided into three stages to compare visual attention between experts and novices using heatmap and gaze plot. Although the expert tended to check each point, the novices tended to have a relatively short gaze of the outer breast region was observed. In the future, a comparative evaluation using clinical images is necessary; however, the eye tracking system to visualize attention contributes to medical safety during positioning.

Cost comparison between open radical cystectomy, laparoscopic radical cystectomy, and robot-assisted radical cystectomy for patients with bladder cancer: a systematic review of segmental costs.

BACKGROUND: Robot-assisted radical cystectomy is becoming a common treatment for bladder carcinoma. However, in comparison with open radical cystectomy, its cost-effectiveness has not been confirmed. Although few published reviews have compared total costs between the two surgical procedures, no study has compared segmental costs and explained their impact on total costs. METHODS: A systematic review was conducted based on studies on the segmental costs of open, laparoscopic, and robot-assisted radical cystectomy using PubMed, Web of Science, and Cochrane Library databases to provide insight into cost-effective management methods for radical cystectomy. The segmental costs included operating, robot-related, complication, and length of stay costs. A sensitivity analysis was conducted to determine the impact of the annual number of cases on the per-case robot-related costs. RESULTS: We identified two studies that compared open and laparoscopic surgeries and nine that compared open and robotic surgeries. Open radical cystectomy costs were higher than those of robotic surgeries in two retrospective single-institution studies, while robot-assisted radical cystectomy costs were higher in 1 retrospective single-institution study, 1 randomized controlled trial, and 4 large database studies. Operating costs were higher for robotic surgery, and accounted for 63.1-70.5% of the total robotic surgery cost. Sensitivity analysis revealed that robot-related costs were not a large proportion of total surgery costs in institutions with a large number of cases but accounted for a large proportion of total costs in centers with a small number of cases. CONCLUSIONS: The results show that robot-assisted radical cystectomy is more expensive than open radical cystectomy. The most effective methods to decrease costs associated with robotic surgery include a decrease in operating time and an increase in the number of cases. Further research is required on the cost-effectiveness of surgeries, including quality measures such as quality of life and quality-adjusted life years.

Efficacy of 'drive and retrieve' as a cooperative method for prompt endovascular treatment for acute ischemic stroke.

BACKGROUND: Outcomes of endovascular treatment for acute ischemic stroke depend on the time interval from onset to reperfusion. Although the centralized 'mothership' method is considered preferable, the required transportation time increases the risk that a patient with a stroke may not receive intravenous or endovascular therapy. In contrast, 'drive and retrieve' describes a system wherein doctors from comprehensive stroke centers travel to primary stroke centers and provide endovascular treatment for acute ischemic stroke. OBJECTIVE: To describe the drive and retrieve system and verify the effects of this new collaboration on outcomes in patients with acute ischemic stroke among facilities. METHODS: This non-randomized, single-arm study retrospectively analyzed patients who met the inclusion criteria for endovascular treatment provided through a drive and retrieve system. Among the 122 patients treated by this system, we analyzed the time of onset to recanalization as the primary outcome. We also analyzed the efficacy of the drive and retrieve system using geographic information system analysis. RESULTS: The median time from onset to recanalization was 229 min (IQR 170-307 min, 95% CI 201 to 252 min). The upper limit of the 95% CI for the time from onset to recanalization was shorter than the median times reported in two previous trials. Geographic information system analysis revealed an upward trend in the population coverage rate in each secondary medical area after the drive and retrieve method was introduced. CONCLUSION: The drive and retrieve method may be an effective form of cooperation between facilities located within 1 hour of a comprehensive stroke center.

Relationships Among Tweets Related to Radiation: Visualization Using Co-Occurring Networks.

BACKGROUND: After the Fukushima Daiichi nuclear accident on March 11, 2011, interest in, and fear of, radiation increased among citizens. When such accidents occur, appropriate risk communication must provided by the government. It is therefore necessary to understand the fears of citizens in the days after such accidents. OBJECTIVE: This study aimed to identify the progression of people's concerns, specifically fear, from a study of radiation-related tweets in the days after the Fukushima Daiichi nuclear accident. METHODS: From approximately 1.5 million tweets in Japanese including any of the phrases "radiation" (), "radioactivity" (), and "radioactive substance" () sent March 11-17, 2011, we extracted tweets that expressed fear. We then performed a morphological analysis on the extracted tweets. Citizens' fears were visualized by creating co-occurrence networks using co-occurrence degrees showing relationship strength. Moreover, we calculated the Jaccard coefficient, which is one of the co-occurrence indices for expressing the strength of the relationship between morphemes when creating networks. RESULTS: From the visualization of the co-occurrence networks, we found high citizen interest in "nuclear power plant" on March 11 and 12, "health" on March 12 and 13, "medium" on March 13 and 14, and "economy" on March 15. On March 16 and 17, citizens' interest changed to "lack of goods in the afflicted area." In each co-occurrence network, trending topics, citizens' fears, and opinions to the government were extracted. CONCLUSIONS: This study used Twitter to understand changes in the concerns of Japanese citizens during the week after the Fukushima Daiichi nuclear accident, with a focus specifically on citizens' fears. We found that immediately after the accident, the interest in the accident itself was high, and then interest shifted to concerns affecting life, such as health and economy, as the week progressed. Clarifying citizens' fears and the dissemination of information through mass media and social media can add to improved risk communication in the future.

[Evaluation of Efficiencies on the Gadoxetic Acid-enhanced MRI for Preoperative Assessment of Liver Metastases from Colorectal Carcinoma].

THE AIMS OF OUR STUDY WERE: 1) to evaluate efficiencies of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI) for preoperative assessment of liver metastases from colorectal carcinoma, and 2) to compare them with other diagnostic imaging modalities. The subjects of the analysis were outpatients with advanced colorectal cancer who are at risk of developing liver metastases (initial setting: pre-test probability=20%). At initial setting, we performed a decision analysis to calculate numbers of true positive (TP), false negative (FN), false positive (FP) and true negative (TN) test results per 1000 patients of Gd-EOB-MRI and other imaging modalities (conventional contrast agent-enhanced MRI, contrast-enhanced CT and 18F-FDG PET/CT). From the result of decision analysis, we calculated the cost of detection per one patient with liver metastases (detection cost). Also, we calculated positive predictive value (PPV) and negative predictive value (NPV). Moreover, these values were defined as efficiencies in this study. In the initial setting, number of TP, FN, FP TN results and detection cost of Gd-EOB-MRI were 197, 3, 40, 760, and 224,032.8 Japanese Yen, respectively. Also, PPV and NPV were 83.1% and 99.7%, respectively. In comparison with other imaging modalities, efficiencies of Gd-EOB-MRI were superior to them, except detection cost. We consider that the efficiencies of Gd-EOB-MRI, which we had assessed are easy to understand and useful when they are used for explanation to patients.

Construction of mammographic examination process ontology using bottom-up hierarchical task analysis.

Describing complex mammography examination processes is important for improving the quality of mammograms. It is often difficult for experienced radiologic technologists to explain the process because their techniques depend on their experience and intuition. In our previous study, we analyzed the process using a new bottom-up hierarchical task analysis and identified key components of the process. Leveraging the results of the previous study, the purpose of this study was to construct a mammographic examination process ontology to formally describe the relationships between the process and image evaluation criteria to improve the quality of mammograms. First, we identified and created root classes: task, plan, and clinical image evaluation (CIE). Second, we described an "is-a" relation referring to the result of the previous study and the structure of the CIE. Third, the procedural steps in the ontology were described using the new properties: "isPerformedBefore," "isPerformedAfter," and "isPerformedAfterIfNecessary." Finally, the relationships between tasks and CIEs were described using the "isAffectedBy" property to represent the influence of the process on image quality. In total, there were 219 classes in the ontology. By introducing new properties related to the process flow, a sophisticated mammography examination process could be visualized. In relationships between tasks and CIEs, it became clear that the tasks affecting the evaluation criteria related to positioning were greater in number than those for image quality. We developed a mammographic examination process ontology that makes knowledge explicit for a comprehensive mammography process. Our research will support education and help promote knowledge sharing about mammography examination expertise.

Investigation of Preferences in Working Environment of Radiological Technologists Using Conjoint Analysis.

The purpose of this study is to assess working environment preferences of radiological technologists using conjoint analysis. We carried a questionnaire survey on working environment preferences for 200 radiological technologists working in medical facilities in Japan. We defined eight characteristics for virtual medical facilities as follows: presence of colleagues who can be consulted, employment status, number of overtime work per month, academic meeting participation, number of hospital beds, presence of nuclear medicine imaging systems and radiation therapy systems, location of medical facilities, and change rate in annual income. A total of 18 virtual medical facilities were selected by an orthogonal array table using above-mentioned characteristics. The acquired data by the pairwise comparison method were analyzed by conjoint analysis. Marginal rates of substitution between income and non-pecuniary characteristics, which represent radiological technologists' preferences, were also calculated. The factors influenced on their preferences were the following: employment status is not part-time, medical facility is smaller in scale, nuclear medicine imaging systems and radiation therapy systems are set up, and the number of overtime work is less. It was suggested that radiological technologists have a tendency to avoid increase of workloads and select his/her working place with emphasis on own experiences.

Estimating the Duration of Public Concern After the Fukushima Dai-ichi Nuclear Power Station Accident From the Occurrence of Radiation Exposure-Related Terms on Twitter: A Retrospective Data Analysis.

BACKGROUND: After the Fukushima Dai-ichi Nuclear Power Station accident in Japan on March 11, 2011, a large number of comments, both positive and negative, were posted on social media. OBJECTIVE: The objective of this study was to clarify the characteristics of the trend in the number of tweets posted on Twitter, and to estimate how long public concern regarding the accident continued. We surveyed the attenuation period of the first term occurrence related to radiation exposure as a surrogate endpoint for the duration of concern. METHODS: We retrieved 18,891,284 tweets from Twitter data between March 11, 2011 and March 10, 2012, containing 143 variables in Japanese. We selected radiation, radioactive, Sievert (Sv), Becquerel (Bq), and gray (Gy) as keywords to estimate the attenuation period of public concern regarding radiation exposure. These data, formatted as comma-separated values, were transferred into a Statistical Analysis System (SAS) dataset for analysis, and survival analysis methodology was followed using the SAS LIFETEST procedure. This study was approved by the institutional review board of Hokkaido University and informed consent was waived. RESULTS: A Kaplan-Meier curve was used to show the rate of Twitter users posting a message after the accident that included one or more of the keywords. The term Sv occurred in tweets up to one year after the first tweet. Among the Twitter users studied, 75.32% (880,108/1,168,542) tweeted the word radioactive and 9.20% (107,522/1,168,542) tweeted the term Sv. The first reduction was observed within the first 7 days after March 11, 2011. The means and standard errors (SEs) of the duration from the first tweet on March 11, 2011 were 31.9 days (SE 0.096) for radioactive and 300.6 days (SE 0.181) for Sv. These keywords were still being used at the end of the study period. The mean attenuation period for radioactive was one month, and approximately one year for radiation and radiation units. The difference in mean duration between the keywords was attributed to the effect of mass media. Regularly posted messages, such as daily radiation dose reports, were relatively easy to detect from their time and formatted contents. The survival estimation indicated that public concern about the nuclear power plant accident remained after one year. CONCLUSIONS: Although the simple plot of the number of tweets did not show clear results, we estimated the mean attenuation period as approximately one month for the keyword radioactive, and found that the keywords were still being used in posts at the end of the study period. Further research is required to quantify the effect of other phrases in social media data. The results of this exploratory study should advance progress in influencing and quantifying the communication of risk.

Trends for the Geographic Distribution of Radiological Resources in Hokkaido, Japan: Data Analysis Using Gini Coefficient and Herfindahl-Hirschman Index.

The aim of this study is to analyze the maldistribution and the trends in the geographic distribution of radiological resources in secondary medical areas of Hokkaido. The distribution was measured by combining the Gini coefficient (GC), which is an indicator of inequality of distribution, and the Herfindahl-Hirschman index (HHI), which is mainly used to assess market concentration. Data concerning the distribution of radiological resources, such as CT, MRI, radiotherapy facilities (RTF), radiological technologists (RT), and medical doctors were obtained from official publications. CT was more equally distributed, and RTF was more inequality than other radiological resources in 2014. Radiological resources excluded CT were higher degree of concentration than population distribution, and it showed that they were located relatively more intensively in urban areas than in rural areas. During the period 1999-2014, the GC for CT, MRI, RTF, and RT decreased, while the HHI increased. These trends indicated increased equality of distribution of CT, MRI, RTF, and RT and the concentration in urban areas. This study suggested that GC and HHI could be powerful indicators for allocation planning of medical resources with further analysis of the maldistribution of medical resources.