Intracavitary Brachytherapy
Intracavitary brachytherapy at Cookridge is used in the treatment of gynaecological tumours. This can involve the uterus, the cervix, or the vaginal wall. A typical treatment for cervical cancer would involve placing radioactive sources in the cervix in a uterine tube, and next to the cervix in the lateral fornices of the vagina in two rubber ovoids. This treatment could be a manual treatment, where radioactive Caesium sources are actually inserted in theatre by the radiotherapist, or a remote after-loading procedure, where the radiotherapist inserts uterine and ovoid applicator tubes. These applicator tubes are connected to remote afterloading machine which contains the radioactive sources. The afterloader delivers the radioactive sources to the applicator tubes under the control of a computer.
The use of an afterloading machine eliminates the unnecessary exposure associated with manual treatments, allows faster, outpatient treatments, and enables more complex treatment techniques to be used. Afterloading has all but replaced manual treatments in intracavitary because of its inherent advantages, except for a few cases where manual insertions are clinically justified. The consultants principally involved with this work are Mr.Ian Rothwell and Dr.Howard Close.
Interstitial Brachytherapy
Interstitial brachytherapy at Cookridge is used in the treatment of squamous cell carcinomas of a wide variety of anatomical sites including oral cavity, skin, anus, vaginal wall, and breast. It may be used as a sole treatment for very localised tumours, or it may be combined with an external beam radiotherapy treatment.
In the early days of interstitial therapy, Radium, and later Caesium, needles were inserted directly into the tumour sites in a regular pattern in order to give the required dose to the tumour. In the 1960's the advent of computerised dose calculations and the availability of Iridium-192 sources gave rise to a different implantation technique called the Paris system. In the UK almost all interstitial implants will be performed with Iridium-192 wires or hairpins, however Radium sources are still in use in the third world owing to their reusability.
For a typical breast implant hollow needles will be inserted through the tumour site in theatre under an anaesthetic. The needles will be held in place with a template. This template helps maintain the uniform arrangement and separation of the needles, creating a more uniform dose distribution. After the operation the patient is removed from theatre and allowed to recover in their room. Sometime after the implant the radioactive sources are loaded into the hollow needles by the radiotherapist. The sources may be in place from 2-6 days depending on the type of treatment and the dose required.
An interesting new application of interstitial brachytherapy is in the treatment of early stage prostate cancer. This technique involves placing 60-120 low activity Iodine-125 seeds in the prostate under ultrasound guidance. The seeds remain permanently in the prostate, and the treatment lasts about a year. After this point the seeds contain negligible radioactivity and are considered harmless. The advantage of the long treatment time is the reduction of unwanted damage to healthy normal tissue surrounding the tumour. This treatment is offered as an alternative to a radical prostactectomy, and has become very popular in the United States where it has been practised for the last eight years. The two consultants involved in this work are Dr.David Bottomley, and Dr.Dan Ash.