Permanent seed brachytherapy for prostate cancer

Permanent seed brachytherapy (pronounced brack-ee-therapy) is when your doctor puts very small radioactive metal seeds into your prostate gland. The seeds slowly release a low level of radiation into the area of the prostate over a few months. It is a type of internal radiotherapy.

With brachytherapy, your doctor puts the radioactive source or seeds as close to the cancer as possible. So that the cancer gets a high dose but nearby tissues and further away the levels of radiation are low. 

Permanent seed brachytherapy is also called permanent brachytherapy or low dose rate (LDR) brachytherapy. 

Depending on your cancer, you might have a different type of brachytherapy called temporary brachytherapy.

When you might have permanent seed brachytherapy

You might have permanent seed brachytherapy for prostate cancer that hasn’t spread outside the prostate gland. This is localised prostate cancer.

Doctors in the UK recommend the best treatment for you depending on your risk group. They may use a system called the Cambridge Prognostic Group (CPG).

You usually permanent seed brachytherapy on its own. 

Your doctor may also recommend you have hormone therapy for a few months before the radiotherapy treatment. The hormone therapy shrinks the prostate cancer and makes it easier to put the seeds into the right place.

How many hospital appointments you might have

You might have the treatment during 1 or 2 stages. This depends on what is available at your hospital. 

1 stage procedure 

If you have the 1 stage procedure you have your brachytherapy planning and treatment on the same day. And you might stay in hospital for a night afterwards.

You'll also have an ultrasound scan a few weeks before treatment to check you're suitable for treatment and to work out how many seeds you need. 

2 stage procedure 

Some hospitals do your planning 2 to 4 weeks before your brachytherapy. At the planning session you have an ultrasound to check how many seeds you need in your prostate.

Then at your second visit your doctor puts in the radioactive seeds.

Before treatment

You meet members of your treatment team. You sign the consent form to agree to the treatment and can ask questions. It helps to write down all your questions beforehand to take with you. The more you know about what is going to happen, the more confident you will feel.

The radiotherapy team

A member of the radiotherapy team tells you about:

  • the treatment you're going to have
  • the benefits
  • the possible risks
  • what to expect afterwards

The anaesthetic

The anaesthetist gives you the anaesthetic and looks after you during the treatment. They make sure you’re fit enough to have it.

The nurse specialist

The nurse checks your:

  • general health
  • weight
  • blood pressure
  • pulse
  • temperature

You might also have a heart tracing (ECG).


You need to tell the treatment team if you are taking any medicines. If you are taking blood thinning drugs you might need to stop taking them up to 2 weeks before having the radiotherapy.

You might start taking a medicine called tamsulosin. It helps you to pass urine. And your doctor might give you antibiotics. They will tell you how long you need to take these medicines for. 


You stop eating for at least 6 hours before the treatment if you're having a general anaesthetic. But you can usually drink water until 2 hours beforehand.

Emptying your bowel

You might need to have an enema to empty your bowel so that it is clear during the treatment. An enema is a liquid that you put into your back passage. Or you might have a liquid medicine (laxative). You need to stay close to a toilet for a few hours afterwards.

During treatment

You go to the operating theatre. Your anaesthetist might put a thin tube into your back to give a spinal anaesthetic so that you feel nothing below the waist. Or you might have a general anaesthetic so that you are asleep.

Your doctor usually puts a thin tube into your penis through the tube that carries urine from your bladder. This is a urinary catheter. The catheter shows the position of the urethra within the prostate gland on ultrasound. It also drains urine from the bladder during the procedure.

Your doctor puts an ultrasound probe into your back passage (rectum). It gives a clear picture of your prostate on a screen. The doctor then uses fine needles to put between 60 to 80 small radioactive seeds into your prostate. The needles go through the area of the skin between the scrotum and back passage (the perineum).

Diagram of seed implantation

The doctor takes out the ultrasound probe and the needles once it's done. 

After treatment

You stay in the operating department until the sedation or anaesthetic wears off. You might wear an oxygen mask for a short time. A nurse then takes you back to your ward. You might have a catheter to drain your urine but your nurse usually takes this out after a few hours. You may also have an X-ray to make sure the seeds are in the right place.

You can usually go home once you can pass urine normally but might need to stay in hospital overnight.

Side effects of permanent seed brachytherapy

Permanent seed brachytherapy can cause some side effects. Everyone is different and the side effects vary from person to person. You may not have all the effects mentioned.

Pain and swelling

You may have some swelling and bruising between your legs where the needles were put in. Your nurse will give you painkillers. Warm baths can also help.

Urine problems

You might have a burning feeling when you pass urine and may see traces of blood for the first few days. You might also need to pass urine more often than usual or have problems passing urine. Try to drink at least 2 litres of water a day. 

Avoid or cut down on drinks that might irritate the bladder such as fizzy drinks and alcohol. Also limit caffeinated drinks like tea, coffee and coke. 


You might feel tired for the first few days after treatment as you recover from the anaesthetic. Rest when you need to.

Blood in semen

You might notice blood in your semen for a few weeks after the treatment. Ejaculation can also be painful at first but tends to settle in time. After a while you may notice that you have very little or no semen due to the radiotherapy.

Problems with your bowels

You may have constipation, loose poo or diarrhoea for a few weeks due to inflammation of the bowel. Tell your doctor or nurse if you have it. They can give you medicine to try and help with these symptoms.

Long term side effects

Some side effects can continue for months or years after treatment. These include leakage of urine and erection problems.   

Safety Precautions

Your doctor will tell you what precautions you need to take after treatment. They might advise you to keep a 1 metre distance from pregnant women or children. This includes not having children on your lap. But you can be in the same room as them for as long as you want. This is usually for around 2 months or so after treatment. 

There is a very small risk that a seed might come out when you go to the toilet. If a seed does come out, don’t touch it. Pick it up using tweezers, tongs or a spoon and flush it down the toilet. Contact your consultant to let them know.

It's safe to have sex and sleep in the same bed as your partner after treatment. For a few months, when having sex you should wear a condom. This is in case a seed comes out.

There is a very small risk that one or more seeds might get loose and move out of the prostate gland. There have been reports of seeds moving into the bladder or lung. When a seed has gone to another part of the body, it does no harm. 

Medical card

When you go home, your doctor gives you a card. You need to keep the card with you at all times for 2 years. It has your personal details and the details of your consultant. It says what procedure you have had in case of an emergency.

Follow up

Around 4 to 6 weeks after treatment you have a CT scan to check that all the seeds are in the right place. You have regular blood tests to check the level of a protein called prostate specific antigen (PSA) in your blood.

  • Prostate cancer: diagnosis and management
    National Institute for Health and Care Excellence (NICE), 2019. Last updated December 2021

  • Cancer: Principles and Practice of Oncology (11th edition)
    VT DeVita, TS Lawrence, SA Rosenberg
    Wolters Kluwer, 2019

  • The Royal College of Radiologists' audit of prostate brachytherapy in the year 2012
    AJ Stewart and others
    Clinical Oncology, 2015. Volume 27, Pages 330-336

  • Low dose rate prostate brachytherapy. Information for patients
    Oxford University Hospitals NHS Foundation Trust. Last updated 2019

  • UK Guidance on radiation protection issues following permanent Iodine-124 seed prostate brachytherapy – IPEM report
    Institute of Physics and Engineering in Medicine, Great Britain. 2012

  • Brachytherapy treatment for prostate cancer – Iodine-125 seed implant. Information for patients: Initial consultation to follow-up
    Royal Berkshire NHS Foundation Trust. Last updated 2021

Last reviewed: 
14 Feb 2023
Next review due: 
14 Feb 2026

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