16. Cervix cancer - The GEC-ESTRO Handbook of Brachytherapy

Cervix cancer

10

THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/09/2023

Figure 11. Variation in utero-vaginal location of applicator and its impact on location of high dose areas in adjacent OARs Schematic anatomical diagrams (sagittal view) showing variation in location of OAR volumes of interest (2 cm 3 and 0.1 cm 3 ) depending on patient anatomy, applicator position and OAR topography. (From ICRU 89)

cannot extend directly e.g., in the lumen of involved bladder and rectum or in the peritoneal cavity (Figure 10). For CT contouring, the CTV-T_IR can be generated with safety margins based on the CTV-T_HR in line with the GEC ESTRO/ ICRU 89 recommendations. For optimal tumour and target contouring, the contouring physician should have performed the gynaecological examination prior to insertion of the applicator. Information from the clinical drawings from gynaecological examination at diagnosis and at the time of BT, as well as MRI at diagnosis and at time of BT with the applicator in situ, should be available at the contouring station. Contouring of tumour volumes should be performed for each insertion of BT applicators on T2-weighted para-axial MRI sequences; para-coronal and sagittal sequences should be inspected during the process to ensure consistency of target contouring in these sequences. The MRI-based target delineation can be superimposed for subsequent fractions of BT if only CT with the applicator in place is used. 7.2 Organ at risk and morbidity concepts Several morbidity endpoints and OAR of interest have been identified based on the typical morbidity profiles seen with cervical cancer radiotherapy. Historically, publications have focussed on the bladder, rectum and bowel. In recent years, there has been increasing interest in various symptoms for a given organ (e.g., rectum: bleeding, proctitis fistula) and in other OARs such as the vagina (sexual outcome), sigmoid and ureter and also in general symptoms (e.g., menopausal symptoms, pain, fatigue). There is also recognition that different specific morbidity endpoints are related to different sub-volumes or points within each OAR (e.g.,

Figure 12. OAR contouring and GTV res , CTV_HR, CTV_IR The outer contour of each OAR should be contoured - bladder (yellow), rectum (brown), sigmoid (orange), bowel (light green). (From EMBRACE II protocol, www.embracestudy.dk)