Radiation dose differences between thoracic radiotherapy planning CT and thoracic diagnostic CT scans

Purpose: To compare the absorbed dose from computed tomography (CT) in radiotherapy planning (RP CT) against those from diagnostic CT (DG CT) examinations and to explore the possible reasons for any dose differences. Method: Two groups of patients underwent CT-scans of the thorax with either DG-CT (n=55) or RP-CT (n=55). Patients from each group had similar weight and body mass index (BMI) and were divided into low (25). Parameters including CTDIvol, DLP and scan length were compared. Results: The mean CTDIvol and DLP values from RP-CT (38.1 mGy, 1472 mGy·cm) are approximately four times higher than for DG-CT (9.63 mGy, 376.5 mGy·cm). For low BMI group, the CTDIvol in the RP-CT scans (36.4 mGy) is 6.3 times higher than the one in the DG-CT scans (5.8 mGy). For high BMI group, the CTDIvol in the RP-CT (39.6 mGy) is 2.5 times higher than the one in the DG-CT scans (15.8 mGy). In the DG-CT scans a strong negative linear correlation between noise index (NI) and mean CTDIvol was observed (r =-0.954, p=0.004); the higher NI, the lower CTDIvol. This was not the case in the RP-DG scans. Conclusion: The absorbed radiation dose is significantly higher and less BMI dependent for RP-CT scans compared to DG-CT. Image quality requirements of the examinations should be researched to ensure that radiation doses are not unnecessarily high

Logical Imputation to Optimize Prognostic Risk Classification in Metastatic Renal Cell Cancer

BACKGROUND: Application of the MSKCC and IMDC models is recommended for prognostication in metastatic renal cell cancer (mRCC). Patient classification in MSKCC and IMDC risk groups in real-world observational studies is often hampered by missing data on required pre-treatment characteristics. OBJECTIVES: To evaluate the effect of application of easy-to-use logical, or deductive, imputation on MSKCC and IMDC risk classification in an observational study setting. PATIENTS AND METHODS: We used data on 713 mRCC patients with first-line sunitinib treatment from our observational European multi-centre study EuroTARGET. Pre-treatment characteristics and follow-up were derived from medical files. Hospital-specific cut-off values for laboratory measurements were requested. The effect of logical imputation of missing data and consensus versus hospital-specific cut-off values on patient classification and the subsequent models' predictive performance for progression-free and overall survival (OS) was evaluated. RESULTS: 45% of the patients had missing data for >= 1 pre-treatment characteristic for either model. Still, 72% of all patients could be unambiguously classified using logical imputation. Use of consensus instead of hospital-specific cut-offs led to a shift in risk group for 12% and 7% of patients for the MSKCC and IMDC model, respectively. Using logical imputation or other cut-offs did not influence the models' predictive performance. These were in line with previous reports (c-statistic similar to 0.64 for OS). CONCLUSIONS: Logical imputation leads to a substantial increase in the proportion of patients that can be correctly classified into poor and intermediate MSKCC and IMDC risk groups in observational studies and its use in the field should be advocated

Distribuição espacial e temporal de Cetengraulis edentulus (Cuvier) (Actinopterygii, Engraulidae) na Baía de Sepetiba, Rio de Janeiro, Brasil Spatial and temporal distribution of Cetengraulis edentulus (Cuvier) (Actinopterygii-Engraulidae) in the Sepetiba Bay, Rio de Janeiro, Brazil

<abstract language="eng">Anchovies are members of the Engraulidae family, characterized to present coastal pelagic habits, concentrating in large schoolings distributed among the continental shelf and semi-closed environment, like bays, where they are target of heavy fisheries. The present study aims to describe spatial and temporal distribution of Cetengraulis edentulous (Cuvier, 1828) in the Sepetiba bay (22º54'-23º04'S, 43º34'-44º10'W) and to assess influences of environmental variables on fish occurrence. A monthly sampling programme was carried out between October 1998 and September 1999, to take both, fish and environmental information on temperature, salinity and depth. Three bay zones were established based on spatial gradient of salinity and depth. Adults C. edentulus were more abundant in the inner bay zone; seasonally, larger size groups (total length > 16 cm) occurred in spring/summer. Significant negative correlations were found between fish abundance and salinity and depth. The close relationship of this species to innermost areas in bays, and the absence of juveniles in sandy beaches, suggest that young-of-the-year use mangrove areas as recruitment sites