Prostate brachytherapy places a radiation source directly inside the prostate, through thin needles passed through the skin between the scrotum and the anus (the perineum). There is no surgical cut. It comes in two forms: permanent low-dose-rate (LDR) seeds, usually placed in a single day procedure, and temporary high-dose-rate (HDR) treatment, where a source is passed into thin tubes for a short time and then removed.
Most people go home the same day or the next day, feel bruised for a few days and return to normal activities within days to weeks. Urinary symptoms are the most common side effect: with seeds they often build up over the first weeks and then settle over months, as the radioactivity fades. Erection changes, if they happen, tend to develop gradually.
This guide follows both paths step by step, from planning to PSA follow-up, using national guidelines and real hospital patient leaflets. Where centres differ, we show the range rather than one number. It is general information, not advice about your own treatment.
Who it is typically offered to
Brachytherapy is one of several options for prostate cancer that has not spread, and the decision is made with your urology and oncology team. National guidelines describe where it fits:
- On its own (monotherapy). The 2017 joint guideline of the American Society of Clinical Oncology and Cancer Care Ontario (ASCO/CCO) says that for low-risk cancer needing active treatment, LDR brachytherapy alone, external beam radiotherapy alone and/or radical prostatectomy should be offered to eligible patients. LDR alone "may be offered" for low-intermediate risk.
- As a "boost" with external beam radiotherapy. For intermediate- and high-risk cancer, the same guideline says a brachytherapy boost (LDR or HDR) should be offered to eligible patients having external beam treatment. In England, NICE guideline NG131 (recommendation 1.3.24) says to consider brachytherapy combined with external beam radiotherapy for Cambridge Prognostic Groups 2 to 5.
- Not alone for higher-risk disease. NICE recommendation 1.3.25: "Do not offer brachytherapy alone to people with CPG 4 and 5 localised or locally advanced prostate cancer."
Practical factors also matter. Macmillan Cancer Support says brachytherapy is not usually suitable if you already have significant urinary symptoms. Centres also look at prostate size: Alberta Health Services, for example, lists a PSA of 20 or less and a small prostate gland among its criteria for LDR seeds. For how this compares with beams from outside, see brachytherapy vs external beam for prostate cancer; for the two types, see LDR seeds or HDR.
The whole journey at a glance
Hospital pages usually describe either seeds or HDR. Here are both paths on one timeline, so you can see where they differ.
Before: planning scan, bowel prep and anaesthesia
The planning scan (volume study)
Your team needs an exact 3D picture of your prostate to calculate how many seeds or how much dose to give and where. Macmillan describes an ultrasound probe placed in the back passage (rectum) to map the prostate. Some centres do this as a separate visit: United Lincolnshire Hospitals (NHS) runs a "volume study" under general anaesthetic, with the implant 4 to 5 weeks later. Others plan on the day of the implant. Alberta Health Services uses a CT scan or a trans-rectal ultrasound to measure prostate size.
Pre-assessment and medicines
Expect a pre-assessment visit to check your general health and fitness for anaesthesia (blood tests, blood pressure and sometimes an ECG). Macmillan says you usually take antibiotics before treatment and for a few days afterwards; many centres also prescribe a tablet to help urine flow. You may be asked to stop some medicines beforehand — only do so on your team's instructions.
Bowel preparation
An empty lower bowel gives clearer ultrasound images. Macmillan mentions a special diet for 24 hours and an enema; United Lincolnshire uses a gas-reducing diet for 3 days and an enema on the morning of the procedure.
Anaesthesia
Macmillan says you will have a general anaesthetic or a spinal anaesthetic with a sedative. At Alberta Health Services, the anaesthetist chooses between general anaesthetic, spinal anaesthetic or conscious sedation. Plan for someone to take you home: you cannot drive afterwards (Macmillan; UW Medicine says not for at least 24 hours, United Lincolnshire 48 hours).
Implant day: LDR seeds vs HDR catheters
LDR seed implant
With you asleep or numb from the waist down, an ultrasound probe in the rectum guides thin needles through the perineum into the prostate. Seeds are released as each needle is withdrawn; no needle passes through the rectum, according to UW Medicine. A catheter may be placed in the bladder during the procedure.
- How many seeds: "around 100" (American Cancer Society), 60–120 on average (Alberta), 70–150 (UW Medicine) — it depends on prostate size and shape.
- How long: about 1–2 hours of treatment (Alberta) or about 2 hours (United Lincolnshire), but you will be in the department most of the day.
- Going home: usually the same day, once you can pass urine (Macmillan, Alberta); some centres keep you overnight (United Lincolnshire).
HDR prostate brachytherapy
Hollow needles or thin plastic tubes (catheters) are placed through the perineum into the prostate, and CT or MRI scans are used to plan the dose. A machine (afterloader) then sends a single radioactive source into the tubes. The ACS describes the source being in place for about 5 to 15 minutes, with usually 1 to 4 sessions over about 2 days; Macmillan says treatment takes about 1 hour and that you must lie down while the tubes are in. The tubes are removed at the end.
Macmillan says HDR alone for early prostate cancer usually takes 2 treatments, and as a boost after external radiotherapy, 1 treatment. You may stay in hospital overnight. Because the source is removed every time, no radiation precautions are needed for other people afterwards.
Recovery timeline: first days, weeks and months
RadiologyInfo (from the American College of Radiology and RSNA) says most patients resume normal activities "within days or weeks". This table puts together what hospital leaflets describe at each stage, mainly for seeds.
| When | What is commonly reported | What centres advise |
|---|---|---|
| First 1–2 days | Soreness and bruising in the perineum; blood in urine; burning when passing urine | Ice pack, painkillers as advised; drink plenty of water; seek help for large clots or if you cannot pass urine |
| First week | Bruising fades slowly; dark brown or black semen | Avoid heavy lifting or strenuous activity: 2 days (United Lincolnshire), 2–3 days (Macmillan), 5 days (UW Medicine); no sex for 2 weeks at some centres |
| Weeks 1–6 | With seeds, urinary frequency, urgency and weak flow often start about a week after the implant and can increase over the first weeks (United Lincolnshire) | Cut down caffeine and alcohol; take the prescribed urine-flow tablet; avoid cycling or horse riding for some weeks (Alberta, UW Medicine) |
| Months 2–8 | Urinary symptoms gradually improve as the seeds lose strength; UW Medicine says they may last 4–8 months | Report persistent or worsening symptoms; follow your precaution end dates |
| Months to years | Possible late effects: urethral narrowing, bowel changes, gradual erection changes | Regular follow-up and PSA tests; tell other doctors about your implant |
After HDR, Macmillan says bladder symptoms usually improve within a few weeks, whereas with seeds improvement can take months while the radioactivity fades.
Side effects: urinary, bowel and sexual — short vs long term
Your team should talk you through your own risks, which depend on your urinary function, prostate size and any other treatment (such as external beam or hormone therapy). These are the effects sources describe:
Urinary
- Short term: needing to go often or urgently, burning and a weaker stream are common in the first weeks and months.
- Urinary retention (being unable to pass urine) needs urgent help. Centres report different rates: about 1 in 20 (Alberta) and 10–15% (United Lincolnshire). Macmillan says swelling may require a catheter for 2 to 4 weeks, occasionally longer.
- Long term: narrowing of the urethra (stricture) can develop weeks, months or years later and may need treatment (Macmillan). The ACS says severe urinary incontinence "isn't common" after brachytherapy; United Lincolnshire quotes a risk of less than 1%.
Bowel
Macmillan says bowel problems usually last a few weeks, sometimes months, and that brachytherapy alone is less likely than external radiotherapy to cause late bowel effects. The ACS says serious long-term problems are uncommon. NICE advises doctors to use caution with biopsies of the front wall of the rectum after brachytherapy because of the risk of fistula — a good reason to tell any doctor who examines your bowel that you have had prostate brachytherapy.
Sexual function and fertility
- Erections: problems may start straight after treatment from swelling, or develop gradually over months or years (Macmillan; ACS). Alberta Health Services reports about 1–3 in 10 people over up to 5 years; United Lincolnshire about 3 in 10 under 60, more often over 60. Risk is higher with existing erection problems, external beam or hormone therapy (Macmillan). Treatments are available.
- Ejaculation: less semen, or none, is common; orgasms may feel different.
- Fertility: may be reduced; sperm can be stored before treatment (Macmillan). You still need contraception.
Living with seeds: MRI, CT, airports and precautions
- People around you. Seeds give off low, fading radiation for months, so centres give time-limited precautions around pregnant people and young children. Read our guide to precautions around partners and children, which compares four hospitals' instructions.
- MRI and CT scans. Some centres use CT and MRI after the implant to check seed positions. The United Lincolnshire leaflet states: "It is safe to have an MRI scan if needed for other investigations." Always tell the radiographer about your implant and show your card.
- Airports. The ACS says low radiation levels can sometimes be picked up by airport detection systems; carry your implant card or a doctor's letter.
- Seed movement. The ACS notes a small risk that seeds move (migrate), with rare reports of seeds reaching the lungs, usually without symptoms or harm; linked strands of seeds reduce this risk.
- Future surgery or cremation. Tell surgeons about the implant. Hospital cards give the period during which they should contact the brachytherapy team (2 years at United Lincolnshire; 20 months at Leeds).
Follow-up and PSA checks
Many centres do a CT scan a few weeks after a seed implant to check where each seed sits and confirm the dose (about 3 weeks at UW Medicine; 4 to 6 weeks at United Lincolnshire). After that, follow-up is built around PSA blood tests.
NICE recommendation 1.3.47 says to check PSA "no earlier than 6 weeks after treatment, at least every 6 months for the first 2 years, and then at least once a year after that." Some centres check more often: UW Medicine's schedule sees patients about every 3 months for the first 18 months.
What "PSA bounce" means
After radiotherapy, PSA usually falls slowly. A PSA bounce is a temporary rise that then falls back without any treatment. It is common after seed brachytherapy and is not, on its own, a sign of cancer returning:
- In a study of 352 men treated with iodine-125 seeds (Journal of Radiation Research, 2018), 117 (about 1 in 3) had a bounce, defined as a rise of at least 0.2 ng/ml above the lowest value followed by a fall back. The median time to the bounce was 20 months.
- In a series of 198 men (Radiation Oncology, 2012), 35.9% had at least one bounce, at a median of 17 months; in 12.5% the rise was big enough to cross the usual threshold for biochemical failure (nadir + 2 ng/ml, the "Phoenix" definition), before falling again.
Because a bounce and a true relapse can look alike at first, doctors interpret PSA trends over time rather than a single result. If your PSA rises, ask your team how they are reading it and when it will be rechecked.
Questions to ask your team
- Am I being offered seeds (LDR) or HDR, alone or as a boost with external beam? Why that option for me?
- Will planning be a separate visit or on the same day? What bowel prep and medicines will I need?
- What kind of anaesthetic is used, and will I stay overnight?
- Based on my current urinary symptoms, how likely am I to need a catheter afterwards?
- What are my personal risks of erection problems and bowel effects, and what support is available?
- Which radiation precautions apply to me, and on what date does each one end?
- Will I get an implant card, and how long should I carry it?
- What is my follow-up and PSA schedule, and how will you tell a PSA bounce from a relapse?
- How many prostate implants does this team do, and who will be present? (See who is in your brachytherapy team.)
For a fuller printable list covering every type of brachytherapy, see our questions to ask before brachytherapy. If something in this guide is unclear or you spot an error, send us your question or correction.
Frequently asked questions
How long is recovery after prostate brachytherapy?
Most people return to normal activities within days or weeks, according to RadiologyInfo. Bruising settles in a few days and centres advise avoiding heavy lifting for 2 to 5 days. With seeds, urinary symptoms often build over the first weeks and then improve over several months as the radioactivity fades.
How many seeds are used in prostate brachytherapy?
It depends on the size and shape of the prostate. The American Cancer Society says around 100 seeds are usually placed; Alberta Health Services gives an average of 60 to 120 and UW Medicine 70 to 150.
Is it safe to have an MRI with prostate seeds?
Some centres use CT and MRI after the implant to check seed positions, and United Lincolnshire Hospitals states it is safe to have an MRI scan for other investigations. Always tell the radiographer about your implant and show your implant card.
What is a PSA bounce after brachytherapy?
A PSA bounce is a temporary rise in PSA that falls back without treatment. In a 2018 study of 352 men with iodine-125 seeds, about 1 in 3 had a bounce, at a median of 20 months. Doctors look at PSA trends over time before deciding whether a rise matters.
Are brachytherapy seeds the same as fiducial markers?
No. Brachytherapy seeds are radioactive and treat the cancer. Fiducial markers are small metal markers placed in the prostate so x-rays can show its position during image-guided external beam radiotherapy, as described by the American Cancer Society.
When can I have sex after prostate seed brachytherapy?
Instructions vary between centres. Some ask you to avoid sex for the first 2 weeks, then use a condom for a period ranging from 1 to 2 weeks up to 2 months, because a seed can occasionally pass in semen. Dark semen for a few weeks is common. Follow your own centre's leaflet.
Sources
- NICE — Prostate cancer: diagnosis and management (NG131), recommendations 1.3.24, 1.3.25, 1.3.47 (accessed 9 October 2026)
- Chin J, et al. Brachytherapy for Patients With Prostate Cancer: ASCO/Cancer Care Ontario Joint Guideline Update. J Clin Oncol. 2017;35(15):1737-1743 (accessed 9 October 2026)
- Macmillan Cancer Support — Brachytherapy for prostate cancer (accessed 9 October 2026)
- American Cancer Society — Radiation Therapy for Prostate Cancer (accessed 9 October 2026)
- RadiologyInfo.org (ACR/RSNA) — Brachytherapy (accessed 9 October 2026)
- Alberta Health Services (Cancer Care Alberta) — LDR brachytherapy for prostate cancer: permanent iodine-125 seed implant (patient leaflet, PDF) (accessed 9 October 2026)
- United Lincolnshire Hospitals NHS Trust — Prostate Seed Brachytherapy (patient leaflet 2236 v2, PDF) (accessed 9 October 2026)
- UW Medicine Urology and Prostate Clinic — Radioactive Seed Implant: after your treatment for prostate cancer (PDF) (accessed 9 October 2026)
- Leeds Teaching Hospitals NHS Trust — Your Prostate Implant Card (LN003722, PDF) (accessed 9 October 2026)
- Kubo K, et al. Clinical features of prostate-specific antigen bounce after 125I brachytherapy for prostate cancer. J Radiat Res. 2018;59(5):649-655 (accessed 9 October 2026)
- Mazeron R, et al. Permanent 125I-seed prostate brachytherapy: early prostate specific antigen value as a predictor of PSA bounce occurrence. Radiat Oncol. 2012;7:46 (accessed 9 October 2026)
Educational content. It does not replace advice from qualified healthcare professionals. Your own treatment team is the right source for decisions about your care. Written by the brachytherapist.com editorial team from the sources listed above. Hospital leaflets are quoted as examples of real-world instructions, not as recommendations for your care.