Research on ghost fishing became active in the late 1980s. Ghost fishing has been confirmed for traps, gillnets, trammel-nets and small seine nets. Some lost traps are functional for a long period of time, even in shallow waters. Consequences for gillnets after loss depend on seabed conditions. The ghost fishing function of gillnets remaining on flat seabeds declines rapidly with decreasing heights and increasing visibility. Gillnets left tangled around an artificial reef, for example, three-dimensionally maintain the initial magnitude of ghost fishing for a long period of time, even after badly fouled. There are increasing numbers of researches working on the total number of mortality per gear after gear loss for gillnets and trammel-nets. It has become also possible to estimate the total number of mortality for a unit period of time in a certain fishing sector. This paper reviews research which has provided evidence and quantitative data on ghost fishing, and proposes five items important for future studies on ghost fishing.

This large international radiation dose survey demonstrates considerable reduction of radiation exposure in coronary CTA during the last decade. However, the large inter-site variability in radiation exposure underlines the need for further site-specific training and adaptation of contemporary cardiac scan protocols.

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BackgroundThe recently developed model-based iterative reconstruction (MBIR) enables significant reduction of image noise and artifacts, compared with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP). The purpose of this study was to evaluate lesion detectability of low-dose chest computed tomography (CT) with MBIR in comparison with ASIR and FBP.MethodsChest CT was acquired with 64-slice CT (Discovery CT750HD) with standard-dose (5.7 ± 2.3 mSv) and low-dose (1.6 ± 0.8 mSv) conditions in 55 patients (aged 72 ± 7 years) who were suspected of lung disease on chest radiograms. Low-dose CT images were reconstructed with MBIR, ASIR 50% and FBP, and standard-dose CT images were reconstructed with FBP, using a reconstructed slice thickness of 0.625 mm. Two observers evaluated the image quality of abnormal lung and mediastinal structures on a 5-point scale (Score 5 = excellent and score 1 = non-diagnostic). The objective image noise was also measured as the standard deviation of CT intensity in the descending aorta.ResultsThe image quality score of enlarged mediastinal lymph nodes on low-dose MBIR CT (4.7 ± 0.5) was significantly improved in comparison with low-dose FBP and ASIR CT (3.0 ± 0.5, p = 0.004; 4.0 ± 0.5, p = 0.02, respectively), and was nearly identical to the score of standard-dose FBP image (4.8 ± 0.4, p = 0.66). Concerning decreased lung attenuation (bulla, emphysema, or cyst), the image quality score on low-dose MBIR CT (4.9 ± 0.2) was slightly better compared to low-dose FBP and ASIR CT (4.5 ± 0.6, p = 0.01; 4.6 ± 0.5, p = 0.01, respectively). There were no significant differences in image quality scores of visualization of consolidation or mass, ground-glass attenuation, or reticular opacity among low- and standard-dose CT series. Image noise with low-dose MBIR CT (11.6 ± 1.0 Hounsfield units (HU)) were significantly lower than with low-dose ASIR (21.1 ± 2.6 HU, p < 0.0005), low-dose FBP CT (30.9 ± 3.9 HU, p < 0.0005), and standard-dose FBP CT (16.6 ± 2.3 HU, p < 0.0005).ConclusionMBIR shows greater potential than ASIR for providing diagnostically acceptable low-dose CT without compromising image quality. With radiation dose reduction of >70%, MBIR can provide equivalent lesion detectability of standard-dose FBP CT.

ancreatic cancer is the fourth leading cause of cancerrelated mortality in the United States. In 2018, an estimated 55 440 people were diagnosed with pancreatic cancer, and 44 330 people died of it (1). Neoadjuvant chemotherapy and radiation therapy (CRT) is increasingly used to treat potentially resectable pancreatic ductal adenocarcinoma (PDA), especially for borderline resectable disease, as an alternative to surgery. CRT improves the rates of negativemargin resections and possibly treats early micrometastatic disease. However, neoadjuvant CRT is not entirely safe and is sometimes associated with toxicity and disease progression. Consequently, it is important to identify patients likely to respond to CRT to avoid unnecessary drug toxicity while maximizing the chances of tumor regression.In PDA, conventional multiphasic CT is the most widely used imaging modality to evaluate response to therapy by using the Response Evaluation Criteria in Solid Tumors (RECIST). However, it is becoming evident that conventional CT imaging-through assessment of serial tumor size changes-is insufficient for reliable response evaluation after neoadjuvant CRT because of poor correlation with histologic grading of response (2-4). This poor performance can be explained by the abundant fibrous stroma of PDA, which cannot be differentiated from posttherapy fibrous scarring.Obtaining negative pathologic margins (R0) after surgery is an important marker of therapy in PDA. Patients with PDA with R0 have significantly longer survival than patients with positive margins (5,6). Recently, the rate of R0 resection is increasing with the use of neoadjuvant CRT. In a study by Chatterjee et al ( 7), R0 resection was achieved in approximately 90% of patients with PDA