16 Cervix Carcinoma

Cervix Cancer 313

anatomy of the patient, packing and shielding are not necessary: after a time period of 24 hours the mould does not move significantly during brachytherapy, and it pushes away the bladder and rectum significantly. At the end of the application a flexible tube with radiopaque markers may be inserted into the rectum and positioned near the anterior rectal wall in order to calculate the dose at specific points inside the rectum. Such a tube may also be used for introducing some contrast medium into the rectum. This is in addition to the ICRU rectum reference point at the anterior rectum wall which needs to be calculated and reported. Two radiographs (anterior-posterior and lateral) are taken with a reference box (isocentric reference frame) after the position is changed from lithotomy to supine with the thighs together (position of brachytherapy) directly after the end of the application (HDR) or later (LDR/PDR/MDR brachytherapy). The position of the applicator (including the packing if used), the bladder balloon, and the rectal probe are checked. The radiographs for treatment planning may be taken later to allow some adaptation of the applicator to the individual patient situation, which usually takes about 24 hours. After this time period, a constant position of the applicator can be assumed. “Manchester” based techniques (59,61,62,116). The classical Manchester technique was based on using one intrauterine tube with a choice of two standard lengths (4 cm and 6 cm) and one non standard length (3.5 cm) (each tube has a rubber flange at its cervical end to hold the tube in the correct position) and two vaginal ovoids ellipsoid in shape, two small (2 cm), two medium (2.5 cm), or large (3 cm) in diameter held apart in the vagina by a washer or a spacer (Fig 6.22). The geometry in vivo was not fixed though in a perfect insertion the ovoid sources are at right angles to the uterine tube. 7.2

Fig 14.6: Modern Manchester applicator set (A) which is available for a Cesium source (LDR, MDR) or - with a smaller tube diameter – for an Iridium source (HDR, PDR). The different angles and lengths of the intrauterine tubes are demonstrated as well as the shape and size of the different ovoids (B,C). There is a clamp to fix the position of the ovoids and the intrauterine tube to each other (Nucletron ®).