Levels and enantiomeric signatures of methyl sulfonyl PCB and DDE metabolites in livers of harbor porpoises (Phocoena phocoena) from the southern North Sea

The concentration of 26 methyl sulfonyl metabolites of polychlorinated biphenyls (MeSO2-PCBs) and of p,p'-DDE (MeSO2-DDE) were determined in 19 liver samples from harbor porpoises (Phocoena phocoena) stranded between 1997 and 2000 on the Belgian and French North Sea Coasts. The total concentration of MeSO2-PCBs ranged from 39 to 4221 ng/g lipid weight (lw) and were generally higher in adults (age >2 yr, range 969-4221 ng/g lw) than in juveniles (age 0.73 or EF < 0.23) for the measured chiral MeSO2-PCB congeners was found in all samples. This result may suggest that one atropisomer may be preferentially formed in harbor porpoises or that the atropisomers are retained in a highly selective manner.Peer reviewe

Assessment of dosimetric errors induced by deformable image registration methods in 4D pencil beam scanned proton treatment planning for liver tumours

PURPOSE: Respiratory impacts in pencil beam scanned proton therapy (PBS-PT) are accounted by extensive 4D dose calculations, where deformable image registration (DIR) is necessary for estimating deformation vector fields (DVFs). We aim here to evaluate the dosimetric errors induced by different DIR algorithms in their resulting 4D dose calculations by using ground truth(GT)-DVFs from 4DMRI. MATERIALS AND METHODS: Six DIR methods: ANACONDA, Morfeus, B-splines, Demons, CT Deformable, and Total Variation, were respectively applied to nine 4DCT-MRI liver data sets. The derived DVFs were then used as input for 4D dose calculation. The DIR induced dosimetric error was assessed by individually comparing the resultant 4D dose distributions to those obtained with GT-DVFs. Both single-/three-field plans and single/rescanned strategies were investigated. RESULTS: Differences in 4D dose distributions among different DIR algorithms, and compared to the results using GT-DVFs, were pronounced. Up to 40 % of clinically relevant dose calculation points showed dose differences of 10 % or more between the GT. Differences in V95(CTV) reached up to 11.34 ± 12.57 %. The dosimetric errors became in general less substantial when applying multiple-field plans or using rescanning. CONCLUSION: Intrinsic geometric errors by DIR can influence the clinical evaluation of liver 4D PBS-PT plans. We recommend the use of an error bar for correctly interpreting individual 4D dose distributions

Distribution of PCB congeners, DDE, hexachlorobenzene, and methylsulfonyl metabolites of PCB and DDE among various fractions of human blood plasma.

The concentrations of chlorinated biphenyls (CBs), 1, 1-bis(4-chlorophenyl)-2,2-dichloroethene (DDE), hexachlorobenzene (HCB), and the methylsulfonyl metabolites of CBs (MeSO(2)-CBs) and DDE (MeSO(2)-DDE) were determined in human plasma samples and in the fractions obtained by ultracentrifugation of plasma into very-low-density (VLDL), low-density (LDL), high-density (HDL) lipoprotein and lipoprotein depleted (LPDP) fractions (containing primarily albumin). The concentrations of triacylglycerols, cholesterol, phospholipids, and apolipoprotein B (apoB) were determined. The organochlorine compounds were associated with all fractions, but predominantly with the LPDP fraction. On an average 44% of CBs, 61% of MeSO(2)-CBs, 73% of DDE, 77% of MeSO(2)-DDE, and 45% of HCB were distributed in the LPDP fraction. A tendency to greater association of 3-methylsulfonyl substituted than of corresponding 4-methylsulfonyl substituted chlorobiphenyls to the LPDP fraction was noticed. Among the lipoprotein fractions, LDL was the main carrier of HCB, DDE and CBs. MeSO(2)-DDE was predominantly found in HDL and MeSO(2)-CBs were distributed equally among the LDL and HDL fractions. Calculating the concentrations of organochlorine compounds in relation to the content of apoB, the levels were about 10 times higher in VLDL than in LDL

Improving hybrid image and structure-based deformable image registration for large internal deformations

Objective. Deformable image registration (DIR) is a widely used technique in radiotherapy. Complex deformations, resulting from large anatomical changes, are a regular challenge. DIR algorithms generally seek a balance between capturing large deformations and preserving a smooth deformation vector field (DVF). We propose a novel structure-based term that can enhance the registration efficacy while ensuring a smooth DVF. Approach. The proposed novel similarity metric for controlling structures was introduced as a new term into a commercially available algorithm. Its performance was compared to the original algorithm using a dataset of 46 patients who received pelvic re-irradiation, many of which exhibited complex deformations. Main results. The mean Dice Similarity Coefficient (DSC) under the improved algorithm was 0.96, 0.94, 0.76, and 0.91 for bladder, rectum, colon, and bone respectively, compared to 0.69, 0.89, 0.62, and 0.88 for the original algorithm. The improvement was more pronounced for complex deformations. Significance. With this work, we have demonstrated that the proposed term is able to improve registration accuracy for complex cases while maintaining realistic deformations