Point A in radiotherapy for Ca cervix corresponds to
Manchester-Point A SystemThe Manchester System was designed for use with LDR radium brachytherapy. It is the most commonly used technique. Point A - Representing the paracervical triangle (where the uterine aery crosses the ureter). This is the commonly repoed dose point. The position has varied several times, but the most modern definition 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 sidewall/obturator nodes, Point B is located 5 cm lateral to the midline at the same level as point A. It also gives a guide as to the lateral spread of the radiation dose.ICRU Repo 38The ICRU released repo 38 regarding dosimetry of cervical cancer brachytherapy. It discouraged the use of Point A and Point B.It also recommended that bladder and rectal point doses be included.Bladder Point - After inseion 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 pa of an anteroposterior line drawn through the center of the balloon.Rectal Point - The rectal point is located 5 mm posterior to the posterior vaginal wall, along with a line perpendicular to the midpoint of the activity of the ovoids.The ICRU also recommended repoing of multiple other dose points, including pelvic wall points. These are not commonly repoed. The repoing 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.(Diagnosis and Management of Cancer by Asok Metha,page73)
Lateral pelvic lymph nodes
Urinary bladder
Rectum
Uterine vessel crossing ureter
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