 Patients with cervix cancer usually require external radiation given to the whole pelvis then an internal radiation boost, also called brachytherapy, to treat any remaining tumour. Standard brachytherapy has been used successfully for many years, but does not take into account differences in the shape of the tumour or normal structures between patients. This study aims to implement individualized -optimized- brachytherapy, based on international recommendations. MR scanning with the intra-uterine applicator in place allows improved identification of residual tumour and normal structures, allowing brachytherapy to be individualized for each patient with the aim to reduce side-effects and improve outcome. Additionally, repeating MR scans during brachytherapy treatment will allow further assessment on motion of the applicator during treatment and the effect on radiation dose. Sexual health assessments aim to identify the relationship between sexual health and treatment effects. 