Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy.

OBJECTIVE: The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion. MATERIALS AND METHODS: This prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements. RESULTS: No significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm. CONCLUSIONS: A better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met.

Impact of rectum and bladder anatomy in intrafractional prostate motion during hypofractionated radiation therapy.

BACKGROUND: The objective was to determine the magnitude of the prostate intrafractional motion relative to bony pelvis anatomy, and to evaluate the relationship between this displacement and some clinical and anatomical variables. MATERIALS AND METHODS: The prospective study consisted of 544 images (375 pre-treatment CBCT and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients that were used for intrafractional prostate motion determination. In addition, two radiation oncologists re-contoured the bladder and rectum on each CBCT according to the patient's anatomy of the day. ANOVA and correlation analysis followed by linear regression analysis were performed to identify clinical or anatomical variables that predict large prostate intrafractional motion. RESULTS: Prostate shift increased in patients with hormone therapy (p ≤ 0.02). The regression analysis showed that patients with large bladder intrafractional filling (p < 0.01) and a large bladder volume difference from planning CT were more likely to experience bigger longitudinal prostate motion (> 3 mm). Recommended bladder size values: anterior-posterior size ≤ 10 cm and anterior-posterior/cranio-caudal ratio ≤ 1.7, both parameters measured in the midsagittal prostate plane, were defined. CONCLUSIONS: The treatment margin should not be reduced for those patients who were treated with hormone therapy and/or whose rectum or bladder was far from complying the preparation protocol conditions.

Mean glandular dose to patients from stereotactic breast biopsy procedures.

The aim of this work is to study the radiation doses delivered to a group of patients that underwent a stereotactic breast biopsy (SBB) procedure. Mean glandular doses (MGD) were estimated from the air-kerma measured at the breast surface entrance multiplying by specific conversion coefficients (DgN) that were estimated using Monte Carlo simulations. DgN were calculated for the 0° and ±15° projections used in SBB and for the particular beam quality. Data on 61 patients were collected showing that a typical SBB procedure is composed by ten images. MGD was on average (4 ± 2) mGy with (0.38 ± 0.06) mGy per image. The use of specific conversion coefficients instead of typical DgN for mammography/tomosynthesis yields to obtain MGD values for SBB that are around a 65% lower on average.

Trends in hepatitis B and hepatitis C seroprevalence among blood donors - Haiti, 2005-2014.

Background and Objectives: Data on the seroprevalence of viral hepatitis are limited in Haiti; consequently, the epidemiology is poorly described. This study aims to provide a descriptive analysis of hepatitis B virus (HBV) and hepatitis C virus (HCV) seroprevalence of blood donations in Haiti. Materials and Methods: Using Haiti's National Blood Safety Program and Haitian Red Cross reports from 2005 to 2014, we analysed the results of screening tests of donor serum samples to assess HBV and HCV seroprevalence among adults aged 17 to 65 years. Results: A total of 198 758 donor samples were screened from 2005 to 2014, of which 0·56% were positive for antibody to hepatitis C virus (anti-HCV) and 3·80% were positive for hepatitis B surface antigen. Over the 10-year study period, anti-HCV seroprevalence among blood donors increased by 31% from 0.66% to 0.86% (95% CI: 1·01-1·70); however, this trend was not uniform over time, with a significant decrease from 0·66% in 2005 to 0·39% in 2009 (95% CI: 0·43- 0·82) and 0·43% in 2012 (95% CI: 0·50-0·90). Conversely, HBV decreased significantly by 13% from 3·95% in 2005 to 3·42% in 2014 (95% CI: 0·77-0·97), a trend that was also observed in 2012 and 2013. Conclusion: The significant, uniform decrease in HBV seroprevalence in more recent years may represent the positive impact of public health interventions in preventing the transmission of blood-borne infections. More research is needed to understand why the trends in HCV transmission are non-uniform and to investigate the significant increase in more recent years.

[Imported cases of dengue fever diagnosed in metropolitan France, from January 2001 to December 2006]. / Dengue d'importation diagnostiquée en France métropolitaine, janvier 2001-décembre 2006.

INTRODUCTION: Dengue fever is the main emerging vector-borne disease worldwide. It was estimated that 40% of the world population is at risk. A potential vector (Aedes albopictus) is present in four French departments of the southeast area of metropolitan France. METHOD: The authors tried to document the number of imported cases of dengue diagnosed from 2001 to 2006, inclusive, as well as their main features. RESULTS: Between 12 and 28 cases of imported dengue were diagnosed every month during that period (eight to 18 cases per month except for years 2001-2002 during which an important dengue epidemic was documented in the French West Indies). Nearly 40% of the cases were imported between June and September during which the vector is active in the metropolitan area. CONCLUSION: This data underlines the strong and close link between the endemic zones of the French territory (French West Indies and Guyana) and the risk of imported cases to metropolitan France. The identification of this "importation track" entails strengthening the system for detecting and managing imported dengue cases in metropolitan France when a dengue epidemic is detected in the French West Indies.