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Purpose: Due to the electron return effect (ERE) during magnetic resonance imaging guided radiotherapy (MRIgRT), rectal gas during pelvic treatments can result in hot spots of over‐dosage in the rectal wall. Determining the clinical impact of this effect on rectal toxicity requires estimation of the amount and mobility (and stability) of rectal gas during treatment. We therefore investigated the amount of rectal gas and local inter‐ and intra‐fractional changes of rectal gas in pelvic cancer patients. Methods: To estimate the volume of gas present at treatment planning, the rectal gas contents in the planning computed tomography (CT) scans of 124 bladder, 70 cervical and 2180 prostate cancer patients were calculated. To estimate inter‐ and intra‐fractional variations in rectal gas, 174 and 131 T2‐w MRIs for six cervical and eleven bladder cancer patients were used. These scans were acquired during four scan‐sessions (~20–25 min each) at various time‐points. Additionally, 258 T2‐w MRIs of the first five prostate cancer patients treated using MRIgRT at our center, acquired during each fraction, were analyzed. Rectums were delineated on all scans. The area of gas within the rectum delineations was identified on each MRI slice using thresholding techniques. The area of gas on each slice of the rectum was used to calculate the inter‐ and intra‐fractional group mean, systematic and random variations along the length of the rectum. The cumulative dose perturbation as a result of the gas was estimated. Two approaches were explored: accounting or not accounting for the gas at the start of the scan‐session. Results: Intra‐fractional variations in rectal gas are small compared to the absolute volume of rectal gas detected for all patient groups. That is, rectal gas is likely to remain stable for periods of 20–25 min. Larger volumes of gas and larger variations in gas volume were observed in bladder cancer patients compared with cervical and prostate cancer patients. For all patients, local cumulative dose perturbations per beam over an entire treatment in the order of 60 % were estimated when gas had not been accounted for in the daily adaption. The calculated dose perturbation over the whole treatment was dramatically reduced in all patients when accounting for the gas in the daily set‐up image. Conclusion: Rectal gas in pelvic cancer patients is likely to remain stable over the course of an MRIgRT fraction, and also likely to reappear in the same location in multiple fractions, and can therefore result in clinically relevant over‐dosage in the rectal wall. The over‐dosage is reduced when accounting for gas in the daily adaption. [ABSTRACT FROM AUTHOR]

Purpose: Dose deposition around unplanned air cavities during magnetic resonance‐guided radiotherapy (MRgRT) is influenced by the electron return effect (ERE). This is clinically relevant for gas forming close to or inside organs at risk (OARs) that lie in the path of a single beam, for example, intestinal track during pelvic treatment. This work aims to verify Monte Carlo calculations that predict the dosimetric effects of ERE around air cavities. For this, we use GafChromic EBT3 film inside poly‐methyl methacrylate (PMMA) –air phantoms. Method: Four PMMA phantoms were produced. Three of the phantoms contained centrally located spherical air cavities (0.5, 3.5, 7.5 cm diameter), and one phantom contained no air. The phantoms were split to sandwich GafChromic EBT3 film in the center. The phantoms were irradiated on an Elekta Unity system using a single 10 × 10 cm2 7‐MV photon beam under the influence of a 1.5‐T transverse magnetic field. The measurements were replicated using the Elekta Monaco treatment planning system (TPS). Gamma analysis with pass criteria 3%/3 mm was used to compare the measured and calculated dose distributions. We also consider 3%/2 mm, 2%/3 mm, and 2%/2 mm pass criteria for interest. Results: The gamma analysis showed that >95% of the points agreed between the TPS‐calculated and measured dose distributions, using 3%/3 mm criteria. The phantom containing the largest air cavity had the lowest agreement, with most of the disagreeing points lying inside the air cavity (dose to air region). Conclusions: The dose effects due to ERE around spherical air cavities are being calculated in the TPS with sufficient accuracy for clinical use. [ABSTRACT FROM AUTHOR]

Aim To evaluate the remineralization ability of two endodontic sealer cements. Methodology Mid-coronal dentine surfaces were subjected to: (i) 37% phosphoric acid ( PA) or (ii) 0.5 mol L−1 ethylenediaminetetraacetic acid ( EDTA) conditioning prior to the application of two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide oxiapatite respectively. Samples were stored in simulated body fluid for 24 h or 21 days. Remineralization of the dentine surfaces were studied by Raman spectroscopy (mapping with K-means cluster and hierarchical cluster analysis) was undertaken. Nanoroughness and collagen fibril width measurements were performed with an atomic force microscopy. ANOVA and Student-Newman-Keuls test were performed (α=0.05). Results Phosphoric acid+oxiapatite promoted both the highest dentine mineralization ( P < 0.05) and crystallographic maturity at the dentine surface. Noncrystalline amorphous-like apatites were also formed. Dentine treated with PA+calcypatite attained the roughest surface ( P < 0.05) with minimal fibril width ( P < 0.05). Cross-linking of collagen only became greater in the group PA+oxiapatite after 21 days. The maximum relative mineral concentration and structure of collagen linked to the amide I and ratio amide III/ AGEs was obtained after using PA+calcypatite at 21-days time-point ( P < 0.05). EDTA produced a lower stoichiometric hydroxyapatite ( P < 0.05) with decreased maturity, at the expense of carbonate band widening, although it favoured the nucleation of carbonated calcium phosphate. Conclusions Dentine surfaces treated with PA+oxiapatite attained the highest dentine remineralization with both crystalline-stoichiometric and amorphous apatites, at 21 days. EDTA conditioning facilitated amorphous-bulk mineral precipitation. The amorphization was more intense after using oxiapatite and provided an ion-rich environment favouring in situ dentine remineralization. [ABSTRACT FROM AUTHOR]

Mycosis fungoides (MF) is the most common variant of primary cutaneous T-cell lymphoma, and decreased forkhead box P3 (FoxP3) expression has been reported in MF late stages. Hypoxia-inducible factor 1 alpha (HIF-1α) may regulate FoxP3 expression; however, it is unknown whether HIF-1α is expressed in the CD4+ T cells of MF patients and how it could affect the expression of FoxP3. Therefore, we evaluated the expression of HIF-1α and FoxP3 in CD4+ T cells obtained from the skin lesions of MF patients. We found increased cell proliferation and an increase in CD4+ T cells with an aberrant phenotype among early stage MF patients. HIF-1α was overexpressed in these CD4+ T cells. In addition, we found a decrease in the percentage of FoxP3+ cells both in the skin of MF patients, when compared with control skin samples, and with disease progression. In addition, a negative correlation was established between HIF-1α and FoxP3 expression. Skin HIF-1α expression in MF patients correlated with the extent of the affected area and increased with the disease progression. Finally, we showed that ex vivo inhibition of HIF-1α degradation increases the percentage of FoxP3+ T cells in skin lesions. Our results suggest that overexpression of HIF-1α affects the levels of FoxP3 in MF patients, which could have relevant implications in terms of disease outcome. [ABSTRACT FROM AUTHOR]

An abstract of the conference paper "Tomographic ultrasound imaging: a novel approach for the determination of progesterone-releasing intrauterine devices," by M. Reyes and colleagues is presented.

An abstract of the conference paper "Longitudinal estimation of fetal growth by ultrasound: a new proposal for the assessment of intrauterine growth restriction," by J. Nien and colleagues is presented.