This directs radiotherapy beams at the cancer from a machine outside the eye. It only treats the area of the body the radiation is directed at.
How you might have it
You may have radiotherapy on its own. Or you might have it with other treatments such as surgery and chemotherapy. The treatment you have and the order you have it depends on the type and size of the cancer. The types of eye cancers that are treated with external beam radiotherapy include:
- lacrimal gland cancer
- squamous cell skin cancer of the eyelid
There are different types of machine that give external radiotherapy. Some are better for treating cancers on the surface of the eye. Others are best for eye cancers that are deeper in the socket. Your radiotherapy specialist (clinical oncologist) carefully chooses the machine that is right for your type of eye cancer.
Types of external radiotherapy you may have for eye cancer are:
- stereotactic radiosurgery
- proton therapy
During your treatment you will meet a number of people. They work together to plan and give you your treatment. These people include:
- radiotherapy doctor - a doctor who specialises in treating cancer with radiotherapy
- radiographer - a person trained to give radiotherapy treatment and operate the machines
Stereotactic radiosurgery uses lots of small thin radiation beams. They target a large dose of radiotherapy on the cancer. You may have a single treatment, or up to 5 treatments.
As treatment is targeted at the cancer, there is less radiation to healthy tissue and fewer side effects. Although it’s called radiosurgery there is no surgery involved.
There are several types of machines that deliver this treatment:
- Linac (linear accelerator)
- Gamma Knife
To have stereotactic radiosurgery your head needs to be kept as still as possible during the treatment. This is called immobilisation. To do this you might have:
- a mask
- a head frame
For the mask, a radiographer uses a special kind of plastic (thermoplastic) that they heat in warm water. This makes it soft and flexible. They put the plastic over your face and neck so that it moulds exactly to the shape of your face.
After a few minutes the plastic gets hard. The radiographer takes the shell off and it is ready to use. During your treatment the mask attaches to a frame. This in turn, attaches to the radiotherapy machine bed while you are wearing it. This means that you can't move, but there is nothing actually attached to you directly.
The following is a video about having a mesh mask fitted. It is just under 2 minutes.
Voiceover: Making a mesh mask for radiotherapy takes a few minutes.
Radiographer: I am just going to heat this up now if you just keep nice and still there and just want to close your eyes for us.
Voiceover: The radiographer softens the mask by putting it in warm water for a minute or two. When the radiographer puts the mask on to your face it will feel warm and damp. They then clip it to the bed that you are lying on. It takes a minute or two to dry into the shape of your face. The radiographers will mark the mask where the light lines are.
Radiographer: OK, you are just going to feel us pressing down on the mask there; you are doing really well are you still ok?
Voiceover: They use the marks on the mask to line up the machine each time you have treatment. The mask keeps your head still and makes sure that your treatment is directed at the cancer. They put your name on the mask and keep it in the radiotherapy department ready for your treatment.
Patient: They told me about the procedure, a mask being fitted, that it would be moulded to the shape of my face. Which they did, three lovely girls put my mind at ease sat me down heated the mask moulded it around my face, not an uncomfortable thing at all to go through.
You might have a head frame for Gamma Knife radiosurgery, although some hospitals use masks instead of frames.
Your radiographer attaches the frame to your skull using 4 pins. You have injections of local anaesthetic at the points where the pins touch your head. This takes about 10 minutes You feel some pressure and tightness, but it usually feels better within a few minutes.
On the day of your treatment, your radiographer takes you to the treatment room. When you are lying comfortably on the couch your head frame or mask is fitted. The radiographers leave the room before treatment starts. Although you are alone, they can see you from the control room.
Once everything is in place, the couch slides into the machine and the treatment begins. You are awake the whole time.
You won't feel anything while you are having treatment. It can take a few hours. Before you start your radiographer will tell you exactly how long your treatment takes.
Proton therapy machines treat eye cancers using a type of radiation known as proton radiation. The proton beams are aimed precisely at the cancer. This type of radiation reduces the risk of damage to the surrounding healthy eye tissue.
You may have this treatment if you can’t have internal radiotherapy (brachytherapy) or surgery to remove the cancer.
Before proton therapy you have an operation to put tiny metal clips (tags) on the outer wall of the eye. You cannot see them, but they are visible on scans. This is important as they help your radiation doctors plan your treatment. You usually have the clips put in under general anaesthetic and they normally stay in place after treatment. They will not affect your eyesight.
You have all your planning and treatment while sitting in a chair designed for this type of radiotherapy. You have 1-2 planning appointments. They involve having a mask made and having x-rays.
The mask makes sure:
- you keep your head completely still during planning and treatment
- you have radiotherapy to the exact same place for each treatment
Your radiographer will explain how they make the mask. They use a type of plastic that does not stick to your skin. Holes are left over your nose and mouth, so your breathing is not affected.
The mask is made at the first appointment. When your mask is ready (on the same day) you have x-rays taken from different angles.
The radiation doctors make sure they have all the information from the x-rays to plan your treatment. You wait in the department while this is being done. Sometimes they may need more x-rays. All together this can take up to 3 hours. Afterwards you may have an appointment to attend a second session.
Between appointments, the radiation doctors work out your individual radiotherapy treatment.
At your second appointment the doctors check your treatment plan is accurate and may make minor changes. This appointment takes about 30 minutes.
You usually have treatment every day for 4-5 days. You might have local anaesthetic eye drops just before. This helps reduce the amount of eye movement. Each treatment takes about 30 seconds, but the appointment takes around 30 minutes. In this time the radiographer makes sure:
- you are in the correct position
- you have the correct dose to the right part of the eye
You are in the room on your own during treatment, and you don’t feel or see anything. Sometimes you can hear a hum or buzz while you have it.
After each appointment a pad is placed over your eye to protect it until the anaesthetic wears off.
After treatment with a head frame
When the treatment is over the frame is removed and the radiographers help you out of the machine. You go back to a ward and usually stay overnight in hospital.
After treatment with a mask
You usually go home after your treatment.
Will I be radioactive?
External radiotherapy does not make you radioactive. It's safe to be with other people throughout your course of treatment, including pregnant women and children.
Travelling to radiotherapy appointments
Tell the radiotherapy department if you prefer treatment at a particular time of day. They can try to arrange this.
Car parking can be difficult at hospitals. It’s worth asking the radiotherapy unit staff:
- if they can give you a hospital parking permit
- about discounted parking rates
- where you can get help with travel fares
- for tips on free places to park nearby
If you have no other way to get to the hospital, the radiotherapy staff might be able to arrange hospital transport for you. But it might not always be at convenient times. To see if you're eligible they usually work it out based on your earnings or income.
Some hospitals have their own drivers or can arrange ambulances. Some charities offer hospital transport.
Side effects of treatment
Radiotherapy for eye cancer has some side effects. The side effects you might have depend on which part of your eye has been treated.