BackgroundOnline magnetic resonance imaging (MRI)-guided radiotherapy of cervical cancer has the potential to further reduce dose to organs at risk (OAR) as compared to a library of plans (LOP)... Show moreBackgroundOnline magnetic resonance imaging (MRI)-guided radiotherapy of cervical cancer has the potential to further reduce dose to organs at risk (OAR) as compared to a library of plans (LOP) approach. This study presents a dosimetric comparison of an MRI-guided strategy with a LOP strategy taking intrafraction anatomical changes into account.MethodsThe 14 patients included in this study were treated with chemo radiation at our institute and received weekly MRIs after informed consent. The MRI-guided strategy consisted of treatment plans created on the weekly sagittal MRI with 3mm and 5mm planning target volume (PTV) margin for clinical target volume (CTV) cervix-uterus (MRI_3mm and MRI_5mm). The plans for the LOP strategy were based on interpolations of CTV cervix-uterus on pretreatment full and empty bladder scans. Dose volume histogram (DVH) parameters were compared for targets and OARs as delineated on the weekly transversal MRI, which was acquired on average 10min after the sagittal MRI.ResultsFor the MRI_5mm strategy D-98% of the high-risk CTV was at least 95% for all weekly MRIs of all patients, while for the LOP and MRI_3mm strategy this requirement was not satisfied for at least one weekly MRI for 1 and 3 patients, respectively. The average reduction of the volume of the reference dose (95% of the prescribed dose) as compared to the LOP strategy was 464cm(3) for the MRI_3mm strategy, and 422cm(3) for the MRI_5mm strategy. The bowel bag constraint V-40Gy<350cm(3) was violated for 13 patients for the LOP strategy and for 5 patients for both MRI_3mm and MRI_5mm strategy.ConclusionsWith online MRI-guided radiotherapy of cervical cancer considerable sparing of OARs can be achieved. If a new treatment plan can be generated and delivered within 10min, an online MRI-guided strategy with a 5mm PTV margin for CTV cervix-uterus is sufficient to account for intrafraction anatomical changes.Trial registrationNL44492.018.13. Show less
Geographical differences in the prevalence of allergic and chronic inflammatory diseases as well as in the efficacy of vaccines have been described. To improve our understanding of... Show moreGeographical differences in the prevalence of allergic and chronic inflammatory diseases as well as in the efficacy of vaccines have been described. To improve our understanding of immunological differences between various human populations, the innate and adaptive immune system and their responses to stimulation have been compared between Europeans and Africans. Furthermore, IgG glycosylation profiles have been compared between several populations and in response to vaccination. In addition, the immune response to controlled human malaria infection has been determined in Europeans and Africans by mass cytometry as well as the role of γδ T cells and CD4+ T cells in immune responses during natural malaria infection in Indonesian children. The results indicated striking differences that need to be taken into account. It might be necessary to develop population-specific vaccines and treatments against infectious, allergic, and chronic inflammatory diseases. Show less
