Practical and technical key challenges in head and neck adaptive radiotherapy: The GORTEC point of view.

Anatomical variations occur during head and neck (H&N) radiotherapy (RT) treatment. These variations may result in underdosage to the target volume or overdosage to the organ at risk. Replanning during the treatment course can be triggered to overcome this issue. Due to technological, methodological and clinical evolutions, tools for adaptive RT (ART) are becoming increasingly sophisticated. The aim of this paper is to give an overview of the key steps of an H&N ART workflow and tools from the point of view of a group of French-speaking medical physicists and physicians (from GORTEC). Focuses are made on image registration, segmentation, estimation of the delivered dose of the day, workflow and quality assurance for an implementation of H&N offline and online ART. Practical recommendations are given to assist physicians and medical physicists in a clinical workflow.

QTL analysis for ascorbic acid content in strawberry fruit reveals a complex genetic architecture and association with GDP-L-galactose phosphorylase.

Strawberry (Fragaria × ananassa) fruits are an excellent source of L-ascorbic acid (AsA), a powerful antioxidant for plants and humans. Identifying the genetic components underlying AsA accumulation is crucial for enhancing strawberry nutritional quality. Here, we unravel the genetic architecture of AsA accumulation using an F1 population derived from parental lines 'Candonga' and 'Senga Sengana', adapted to distinct Southern and Northern European areas. To account for environmental effects, the F1 and parental lines were grown and phenotyped in five locations across Europe (France, Germany, Italy, Poland and Spain). Fruit AsA content displayed normal distribution typical of quantitative traits and ranged five-fold, with significant differences among genotypes and environments. AsA content in each country and the average in all of them was used in combination with 6,974 markers for quantitative trait locus (QTL) analysis. Environmentally stable QTLs for AsA content were detected in linkage group (LG) 3A, LG 5A, LG 5B, LG 6B and LG 7C. Candidate genes were identified within stable QTL intervals and expression analysis in lines with contrasting AsA content suggested that GDP-L-Galactose Phosphorylase FaGGP(3A), and the chloroplast-located AsA transporter gene FaPHT4;4(7C) might be the underlying genetic factors for QTLs on LG 3A and 7C, respectively. We show that recessive alleles of FaGGP(3A) inherited from both parental lines increase fruit AsA content. Furthermore, expression of FaGGP(3A) was two-fold higher in lines with high AsA. Markers here identified represent a useful resource for efficient selection of new strawberry cultivars with increased AsA content.

MRI-guided clinical 6-MV radiosensitization of glioma using a unique gadolinium-based nanoparticles injection.

AIM: This study reports the use of gadolinium-based AGuIX nanoparticles (NPs) as a theranostic tool for both image-guided radiation therapy and radiosensitization of brain tumors. MATERIALS & METHODS: Pharmacokinetics and regulatory toxicology investigations were performed on rodents. The AGuIX NPs' tumor accumulation was studied by MRI before 6-MV irradiation. RESULTS: AGuIX NPs exhibited a great safety profile. A single intravenous administration enabled the tumor delineation by MRI with a T1 tumor contrast enhancement up to 24 h, and the tumor volume reduction when combined with a clinical 6-MV radiotherapy. CONCLUSION: This study demonstrates the efficacy and the potential of AGuIX NPs for image-guided radiation therapy, promising properties that will be assessed in the upcoming Phase I clinical trial.

High-order averaging schemes with error bounds for thermodynamical properties calculations by molecular dynamics simulations.

We introduce high-order formulas for the computation of statistical averages based on the long-time simulation of molecular dynamics trajectories. In some cases, this allows us to significantly improve the convergence rate of time averages toward ensemble averages. We provide some numerical examples that show the efficiency of our scheme. When trajectories are approximated using symplectic integration schemes (such as velocity Verlet), we give some error bounds that allow one to fix the parameters of the computation in order to reach a given desired accuracy in the most efficient manner.