title: Proposed genitalia contouring guidelines in anal cancer intensity-modulated radiotherapy.
abstract: OBJECTIVE
  Intensity-modulated radiotherapy (IMRT) for anal canal carcinoma (ACC) is associated with favourable toxicity outcomes. Side effects include sexual dysfunction, skin desquamation, pain and fibrosis to perineum and genitalia region. The genitalia are situated anterior to the primary ACC between two inguinal regions providing a challenging structure to avoid. Techniques improving outcomes require robust, consistent genitalia contouring to ensure standardization and production of fully optimized IMRT plans. Official recommendations for genitalia contouring are lacking. We describe a potential genitalia contouring atlas for ACC radiotherapy.
  
  
  METHODS
  Following a review of genitalia CT anatomy, a contouring atlas was generated for male and female patients positioned prone and supine. Particular attention was paid to the reproducibility of the genitalia contour in all planes.
  
  
  RESULTS
  Male and female genitalia positioned prone and supine are described and represented visually through a contouring atlas. Contoured areas in males include penis and scrotum, and in females include clitoris, labia majora and minora. The muscles, bone, prostate, vagina, cervix and uterus should be excluded. The genitalia contour extends laterally to inguinal creases and includes areas of fat and skin anterior to the symphysis pubis for both genders.
  
  
  CONCLUSIONS
  This atlas provides descriptive and visual guidance enabling more consistent genitalia delineation for both genders when prone and supine. The atlas can be used for other sites requiring radiotherapy planning.
  
  
  CONCLUSIONS
  This atlas presents visual contouring guidance for genitalia in ACC radiotherapy for the first time. Contouring methods provide reproducible genitalia contours that allow the provision of accurate dose toxicity data in future studies.
authors.affiliation: The Royal Marsden NHS Foundation Trust, Sutton, UK.
authors.forename: C
authors.initials: C
authors.lastname: Brooks
authors.affiliation: The Royal Marsden NHS Foundation Trust, Sutton, UK.
authors.forename: V N
authors.initials: VN
authors.lastname: Hansen
authors.affiliation: The Royal Marsden NHS Foundation Trust, Sutton, UK.
authors.forename: A
authors.initials: A
authors.lastname: Riddell
authors.affiliation: The Royal Marsden NHS Foundation Trust, Sutton, UK.
authors.forename: V A
authors.initials: VA
authors.lastname: Harris
authors.affiliation: The Royal Marsden NHS Foundation Trust, Sutton, UK.
authors.forename: D M
authors.initials: DM
authors.lastname: Tait
mesh_terms: D001005:Anus Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D001271:Atlases as Topic; D005260:Female; D005836:Genitalia, Female / Q000000981:diagnostic imaging*; D005837:Genitalia, Male / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D058958:Organs at Risk / Q000000981:diagnostic imaging; D010347:Patient Care Planning; D016684:Prone Position; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D015203:Reproducibility of Results; D016683:Supine Position; D014057:Tomography, X-Ray Computed