Treatment CourseThere is one radiation unit (OPTIS 2) for the treatment of ocular melanomas. Deep-seated tumors can be treated in parallel at Gantry 1 and Gantry 2. The course of treatment is very different with regard to preparation procedures and duration of therapy.
Deep-seated TumorsNew requests for treatment usually reach us via e-mail or telephone from a referring doctor or sometimes from a patient directly (handling of a new inquiry).
Patients are selected for proton therapy based on the greater medical benefits they could gain in comparison to conventional therapies. Once a week our team holds a Tumor Board Meeting, where all potential cases are presented, and their indications for therapy at CPT are reviewed and discussed. When a patient is accepted for treatment by the Tumor Board, an invitation to the CPT for an informative conversation is issued.
A computer tomography (CT) is necessary to plan the therapy. To this end and to facilitate an exactly reproducible position, the patient is fitted with an individual support. This can consist of a mask, a bite-block or a vacuum mattress, or a combination of supports. The tumor is drawn into the CT slice images. In order to protect the organs which are at greatest risk, their contours are also drawn into the slice images. The whole course of the treatment is then planned and the exact dose to be administered is calculated. Our doctors will also take up contact with the referring physicians in order to ensure a reliable exchange of information and continual medical care before, during and after treatment.
Administration of the Treatment
The total duration of the treatment series depends on the type of tumor, on the therapies previously administered, and on those planned for after proton therapy. Usually our patients are irradiated on an out-patient basis from Monday to Friday for five to eight weeks with a daily dose of 1.8 to 2.0 Gy(RBE). On average, a patient lies either on the back or face-down for between 30 and 60 minutes without moving. Most of this time is used in positioning the patient with the greatest possible care. Immediately before treatment, the precision of the patient’s position is measured by means of two x-rays. The irradiation itself lasts only a few minutes.
Small children are treated under sedation, making it possible for them to remain exactly positioned during treatment. Radiation treatment under sedation is made possible through a close cooperation with the Anesthesia Team of the Children’s Hospital of Zürich.
Our patients receive appointments, on which they can base their personal schedules. However, we are limited by technical and organizational factors that do not allow us to change fixed appointment at will and can also result in delays during the course of treatment.
Place of Residence
Because acute side effects during the series of treatments are so seldom in almost all of our patients, it is only rarely necessary that a patient must be admitted to one of the local hospitals. Usually, these are chemo-therapy patients. All other patients are treated on an outpatient basis and either come from home every day or live in a hotel or vacation apartment in the vicinity of PSI. Our secretaries gladly offer their help in finding appropriate accommodations. Although proton therapy is generally very well tolerated, our patients should not live alone during the series of treatments, but should rather have a family member or friend with them.
The program of ocular proton therapy (using protons to treat patients who suffer from tumors of the eye) runs at PSI since 1984.
Positioning control for eye radiation
Preparation for Treatment
Before a definite decision is made for proton treatment, all patients are examined in detail at the University Eye Clinic in Lausanne (Hôpital Ophtalmique Jules Gonin). The referral of patients for proton therapy is fully in the competence of the ophthalmologist. Patients eligible for proton therapy will undergo surgery during which several small clips are sutured on the sclera (eye surface) in the proximity of the tumor. These clips will allow localization of tumor during the treatment with sub-millimeter accuracy. Patient arrives at PSI typically a few days after the surgery. Upon arrival, patient receives general information about treatment and undergoes steps necessary for the preparation of treatment. This includes creating an individual face mask with a small bite block, which helps the patient to keep his head completely still during treatment. In the next step, x-ray imaging of an eye is performed. These images are necessary for preparation of a treatment plan and for the later alignment of patient in front of the proton beam. After the imaging, patient leaves home and additional preparatory steps are performed in his absence. All prepared treatment plans are consulted with the ophthalmologists in Lausanne.
Administration of the Treatment
The treatment takes place at PSI on an out-patient basis, in the following week on 5 consecutive days and consists of a dry-run and a series of four treatments. During the dry-run, we verify whether there are not any limitations and patient positioning and treatment can be done in the fashion as intended in the treatment plan. The total dose delivered to the tumor is typically 60 Gy RBE. This dose is divided into four daily fractions of 15 Gy RBE. The irradiation itself lasts only about 60 seconds. However, the whole procedure requires about 20 minutes every day. Most of time is spend on the positioning of patient with the sub-millimeter accuracy. In order to keep the eye in the desired position for treatment, the patient must stare on an exactly calculated point of light. Before each treatment the position of the eye and the tumor are checked by means of x-ray images. The treatment is painless. In most cases the whole procedure, including surgery in Lausanne, takes approximately two to three weeks.