MoNuSAC2020: A Multi-Organ Nuclei Segmentation and Classification Challenge.

Detecting various types of cells in and around the tumor matrix holds a special significance in characterizing the tumor micro-environment for cancer prognostication and research. Automating the tasks of detecting, segmenting, and classifying nuclei can free up the pathologists' time for higher value tasks and reduce errors due to fatigue and subjectivity. To encourage the computer vision research community to develop and test algorithms for these tasks, we prepared a large and diverse dataset of nucleus boundary annotations and class labels. The dataset has over 46,000 nuclei from 37 hospitals, 71 patients, four organs, and four nucleus types. We also organized a challenge around this dataset as a satellite event at the International Symposium on Biomedical Imaging (ISBI) in April 2020. The challenge saw a wide participation from across the world, and the top methods were able to match inter-human concordance for the challenge metric. In this paper, we summarize the dataset and the key findings of the challenge, including the commonalities and differences between the methods developed by various participants. We have released the MoNuSAC2020 dataset to the public.

Evaluation of the Prevalence of Shielding in Patients Undergoing Conventional Radiological Procedures (1 Work Shift-1 X-ray Room).

OBJECTIVES: This study aimed to evaluate the prevalence of shielding in patients undergoing conventional radiological procedures (1 work shift-1 x-ray room).The increased number of patients undergoing x-ray examinations has created a global concern due to the stochastic and nonstochastic association with x-ray exposure. Shielding is an efficient method of protecting radiosensitive organs when performing radiological examinations. MATERIALS AND METHODS: Thirty radiography students were sent to conventional radiology departments to act as observers in the control booth of an x-ray room when a radiological procedure was being performed. RESULTS: Of the 30 hospitals evaluated, 13% regarded shielding of radiosensitive organs. The prevalence of shielding in the hospitals where shielding of radiosensitive organs was implemented varied from 5.2% to 14%. CONCLUSION: The results of this study showed that shielding of radiosensitive organs was not performed in the majority of hospitals. More studies are needed to establish the potential causes of low shielding prevalence.If these findings, which were obtained over 1 work shift and in 1 x-ray room, are representative of a large number of medical imaging centers, this raises global concerns regarding shielding of radiosensitive organs, in particular gonad shielding.

Radiation Dose to the Thyroid and Gonads in Patients Undergoing Cardiac CT Angiography.

BACKGROUND: The present data show a global increase in the rate of cardiovascular disease. Cardiac CT angiography has developed as a fast and non-invasive cardiac imaging modality following the introduction of multi-slice computed tomogaraphy. OBJECTIVES: The aim of this study was to measure the radiation dose to the thyroid and pelvis regions in patients undergoing cardiac CT angiography using the Care Dose 4D method of 64-slice scanner. PATIENTS AND METHODS: Eighty-one patients (41 males and 40 females) who were diagnosed with suspected coronary artery disease and were referred to Golestan Hospital, Imaging Department were recruited. Inclusion criteria were based on the protocol of multi-slice CT coronary angiography. The radiation dose to the thyroid and pelvis regions was measured using thermo luminescent dosimeters (TLDs). RESULTS: The mean radiation dose to the thyroid in male and female subjects was 0.32 mSv and 0.41 mSv, respectively (P = 0.032) (total mean, 0.36 mSv). The mean radiation dose to the pelvis in male and female subjects was 81 µSv and 112 µSv, respectively (P = 0.026) (total mean, 96.5 µSv). CONCLUSIONS: The total mean radiation dose to the thyroid and gonads was 0.36 mSv, and 96.5 µSv, respectively for the subjects. These values were high for one organ in a single study. Gender can affect the radiation dose to the thyroid and gonads. This can be attributed to the anatomical characteristic differences of the male and female subjects.

Effect of connector width on stress distribution in all ceramic fixed partial dentures (a 3D finite element study).

STATEMENT OF PROBLEM: Connectors in fixed partial dentures (FPDs) are the weakest areas and responsible for failure in most cases. Optimizing the design of connectors will lead to higher strength and better performance of all-ceramic FPDs. PURPOSE OF STUDY: The aim of this study was to use the finite element method in order to simulate the effect of connector width on stress distribution in all-ceramic FPDs. MATERIAL AND METHODS: Three 3-dimensional finite element models for a 3-unit FPD made of IPS-Empress 2 representing a lower first molar were created and a static load of 500 N was applied axially at mid pontic area. By choosing three different widths, 3 mm, 4 mm, 5 mm for connectors, three models I,II, and III for complete assembly of teeth and connectors were created. RESULTS: Maximum stress occurred in the connector area in all models. Compared to model I, stress decreased 24% in model III; so the wider connector lead to lower stress values. CONCLUSION: Connectors are the most regular area for the fracture in all-ceramic FPDs because of high concentration of stress. Decreasing the width of connector raises the stress and increases the risk for fracture. Also, maximum stress in bridges is less than half of the strength of IPS-Empress2 and no failure is expected for all cases. CLINICAL IMPLICATIONS: This in vitro study of 3-unit all ceramicFPDs made with IPS-Empress2 shows that an increase in the width of connector reduces the stress concentration and improves the likelihood of long-term prognosis. Also, IPS-Empress2 can be used in posterior regions in many cases.