External Beam Radiotherapy


Brachytherapy aims to increase the dose received by the primary tumour mass without increasing toxicity to the adjacent small bowel, bladder and rectum unnecessarily.


There are several brachytherapy systems used. As computer planning becomes more mainstream, these are falling out of favour but the principles remain important.

Manchester Point A System

The Manchester System was designed for use with LDR radium brachytherapy. It is the most commonly used technique. It was published in 1938 by Tod and Meredith and remains in use today. Refinement of the method occurred in the 1950s. Most centres use a tandem (long tube that is inserted into the uterine cavity) and two ovoids/colpoplasts that lie laterally to the tandem.

For a good powerpoint presentation on the Manchester system, see the powerpoint presentation here (from the AAPM)

  • Point A - Representing the paracervical triangle (where uterine artery crosses the ureter). This is the commonly reported dose point. The position has varied several times, but the most modern definition (from 1953) is 2 cm along the most inferior source within the tandem (alternatively 2 cm along the tandem from the external cervical os), and 2 cm lateral to the tandem. Point A is recorded for all brachytherapy treatments, even those that use image-guided techniques.
  • Point B - Representing the pelvic side wall/obturator nodes, Point B is located 5 cm lateral to midline at the same level as point A. It also gives a guide as to the lateral spread of the radiation dose.

ICRU Report 38

The ICRU released report 38 regarding dosimetry of cervical cancer brachytherapy. It discouraged the use of Point A and Point B (to little avail). It also recommended that bladder and rectal point doses be included in reports.

  • Bladder Point - After insertion of a Foley catheter, the balloon is inflated with 7 ml of contrast. The catheter is then pulled until the balloon rests against the urethra. The bladder point is the most posterior part of an antero-posterior line drawn through the centre of the balloon.
  • Rectal Point - The rectal point is located 5 mm posterior to the posterior vaginal wall, along a line perpendicular to the midpoint of the activity of the ovoids.

The ICRU also recommended reporting of multiple other dose points, including pelvic wall points. These are not commonly reported. The reporting of the dose delivered to the treatment volume was based on the length, width and depth of the pear-shaped volume generated by the treatment.


Simulation/Insertion (Tandem/Ovoids)

  • Obtain informed consent
  • Anaesthetics and ultrasound imaging must be available. Some centres also have gynaecological oncology support on hand.
  • Cervical applicator is inserted under general anaesthetic (or spinal anaesthetic/epidural if this is not possible)
  • Position patient in lithotomy
  • Examination under anaesthesia
    • Locate external cervical os
    • Evaluate ability to insert tandem/ovoids
    • Cancel procedure if not possible or consider evaluation by gynaecological oncologist
  • Prep/drape
  • Insert IDC
    • 7 mL mixed contrast/water in balloon (to determine ICRU bladder point)
    • 200-300 mL saline in bladder to allow visualisation of cervix/uterus with ultrasound and push small bowel superiorly
  • Sound cervix/uterus
    • Evalute distance with ultrasound guidance
    • Ensure no perforation
  • Dilate cervix
  • Inserted appropriate sized and angled tandem
    • Check position with ultrasound
  • Insert ovoids (right then left)
  • Lock in position
  • Pack vagina anterior and posterior to ovoids
  • Wake patient
  • CT Scan in position



There are multiple doses used.
A commonly used dose is 24 Gy in 8 fractions.



Wikibooks (Cervical Cancer/Brachytherapy) - See link here
American Brachytherapy Society Guidelines