If you have been told that your cervical cancer treatment will include "internal radiotherapy" or "brachytherapy", you are hearing about a part of treatment that many patients find the hardest to picture in advance. It is also one of the most important parts.
The short version: brachytherapy places a radioactive source inside the vagina and the uterus, right next to the tumour, for a few minutes at a time. That lets your team give the cervix a much higher dose than external beams alone could safely give, while the bladder and bowel nearby receive less. The American Cancer Society describes it as mainly "used in addition to EBRT as a part of the main treatment for cervical cancer", and only rarely used alone in very specific early-stage cases.
This guide walks through why it is used, the applicators, the number of sessions, what a treatment day involves, how pain is managed, and what recovery and side effects look like. It is general information drawn from the sources listed at the end, not advice about your own treatment.
Why brachytherapy is part of cervical cancer treatment
For cervical cancer that has grown beyond a very small, early stage, the usual radiotherapy-based treatment has three parts: external beam radiotherapy to the pelvis, chemotherapy given at the same time (chemoradiation), and then brachytherapy to the cervix and surrounding tissue. Macmillan Cancer Support says brachytherapy "is usually given after external radiotherapy", and the American Cancer Society notes it may be given after concurrent chemoradiation is complete.
The reason is dose. External beams have to pass through healthy organs to reach the cervix. Brachytherapy puts the source inside, so the dose is highest at the tumour and falls off quickly with distance. The American Brachytherapy Society (ABS) "recommends the use of brachytherapy as a component of the definitive treatment of locally advanced cervical carcinoma" (FIGO stages IB2 to IVA in its 2012 guideline), and recommends a combined total dose of roughly 80 to 90 Gy from external beam and brachytherapy together.
For a broader comparison of the two forms of radiotherapy, see how brachytherapy is combined with external beam radiotherapy.
Applicators explained: tandem, ovoids, ring and needles
An applicator is the hollow device that holds the radioactive source in the right place. It is not radioactive on its own: once it is positioned and checked, a machine called an afterloader sends the source through it and pulls it back again (see how HDR brachytherapy and the afterloader work).
| Applicator | What it is, in plain words | When it tends to be used |
|---|---|---|
| Tandem | A thin tube passed through the cervix into the uterus. The American Cancer Society calls it a "small metal tube". | Almost always part of intracavitary treatment when the uterus is still in place. |
| Ovoids | Two small rounded holders that sit in the top of the vagina on either side of the cervix ("tandem and ovoids"). | One of the two classic designs paired with the tandem. |
| Ring | A ring-shaped holder that sits around the cervix instead of two ovoids ("tandem and ring"). | The other classic design; choice depends on anatomy and centre preference. |
| Interstitial needles or catheters | Fine needles or plastic tubes placed into the tissue itself, sometimes alongside a tandem and ring/ovoids ("hybrid"). | When the tumour is too large or irregular to be covered from inside the cavity alone. |
| Vaginal cylinder | A smooth rounded tube placed in the vagina. | After a hysterectomy; see our guide to vaginal cuff brachytherapy after hysterectomy. |
The American Cancer Society notes that intracavitary brachytherapy — the source placed inside the uterus and vagina — is "the type of brachytherapy used most often to treat cervical cancer". The ABS guideline lists tandem and ring, ovoids, cylinder and interstitial applicators, and says interstitial treatment "may be considered for a small proportion of patients" and "should be performed by practitioners with special expertise". If interstitial needles are suggested for you, it is reasonable to ask how often the centre does them.
How many sessions of brachytherapy for cervical cancer, and over how long?
There is no single number. With high-dose-rate (HDR) brachytherapy, the schedules described in guidelines and hospital leaflets range from about 2 to 6 sessions, depending on the centre and whether you still have your uterus. Each time, the source is in for minutes and is then removed. Low-dose-rate (LDR) or pulsed-dose-rate (PDR) treatment instead keeps the applicators in for a longer period with a hospital stay.
Here is what different sources describe:
| Source | What it says about sessions and timing |
|---|---|
| American Brachytherapy Society (HDR guideline, 2012) | "The most common HDR fraction size used in the United States… has been 6 Gy for 5 fractions." Its table also lists schedules such as 4 × 7 Gy, 6 × 5 Gy and 5 × 5.5 Gy. |
| Cancer Research UK | Inpatient treatment: "up to 4 treatments", given twice daily over a few days or once weekly. |
| Macmillan Cancer Support | HDR: "several treatments", each "over about 10 to 15 minutes"; as an outpatient you go to hospital "3 or 4 times over several days or a week". LDR: usually a stay of "12 to 24 hours". |
| American Cancer Society | HDR is "an outpatient procedure over several treatments (often at least a week apart)"; LDR "is completed over a few days" in a private hospital room. |
Two practical consequences follow. First, "several treatments" can mean several separate insertions of the applicator, or — in some centres — one insertion that stays in place for two or more treatments over a day or two. Second, the minutes of radiation are a small part of the day; preparation, imaging and planning take most of the time. Ask your team which pattern your centre uses.
A treatment day, step by step
Details vary between hospitals, but the patient-information pages from Cancer Research UK and Macmillan, and the ABS guidelines, describe a broadly similar sequence for treatment with a tandem-based applicator:
- Preparation. If an anaesthetic is planned, your centre will give you fasting instructions; some also ask you to prepare your bowel. Follow your own hospital's leaflet.
- Anaesthetic or sedation. Cancer Research UK describes either "an injection into your spine (epidural) so you are numb below the waist" or "a general anaesthetic, which puts you to sleep". Macmillan mentions general or spinal anaesthetic when a tube is placed in the womb.
- Applicator insertion. The doctor places the applicators into the uterus and vagina. A catheter is put into the bladder, and gauze packing may hold the applicators steady.
- Imaging. You have "a CT and, or MRI scan to check the position of the applicators" (Cancer Research UK). The ABS recommends MRI "with the brachytherapy apparatus in place" where possible, and says MRI, CT or X-ray imaging may be used for planning.
- Planning. On the images, the oncologist outlines the area to treat and the nearby organs (bladder, rectum, bowel). A physicist or dosimetrist then calculates how long the source should pause at each point. You rest while this is done; RadiologyInfo notes that the whole procedure, including placing the device, "may take up to several hours". Meet the team who plans your treatment.
- Treatment. The applicator is connected to the afterloader by tubes. Staff leave the room and watch and talk with you over camera and intercom. The source travels in, pauses at the planned positions, and returns — Macmillan says each HDR treatment is given "over about 10 to 15 minutes".
- Removal and going home. The applicators and catheter are removed. Cancer Research UK says patients can usually go home on the same day.
What "image-guided" planning means in patient terms
Older brachytherapy was planned on X-rays to a fixed reference point (called "point A"). Since the mid-2000s, the European GEC-ESTRO working group and later the International Commission on Radiation Units and Measurements (ICRU Report 89, 2013) set out how to plan on 3D images instead: the team outlines the tumour as it looks on the day, with the applicator in, and shapes the dose to it. The ABS adopted the GEC-ESTRO approach in its 2012 guideline.
For you, this mostly means an extra scan on each treatment day and a wait while the plan is made. It is also why your plan can change slightly from one session to the next as the tumour shrinks.
Are you radioactive afterwards?
No. With HDR and PDR the source goes back into the machine. Cancer Research UK puts it simply: "You are only radioactive when the treatment machine is switched on", so "afterwards you are safe to be around everyone, including children." See radiation precautions for family and visitors for the full picture.
Does brachytherapy for cervical cancer hurt?
The radiation itself is not felt — Macmillan states that "the actual delivery of treatment will cause no pain or burns". Discomfort comes from the applicator: its insertion (done under anaesthetic or sedation), lying still with it in place, and soreness once it is removed. Macmillan notes that "the applicators can be uncomfortable, so you may need to take painkillers while they are in."
After treatment, Cancer Research UK mentions that some people have "slight bleeding from your vagina" or "mild period like cramps". Tell your team if pain is not controlled — that is a routine request, not a nuisance. Our guide is brachytherapy painful? compares comfort and anaesthesia across treatment types.
After treatment: side effects, vaginal changes and dilators
Because brachytherapy is usually given straight after chemoradiation, the American Cancer Society points out that it can be hard to say which part of treatment caused which side effect. Effects fall into two groups.
Short-term effects (days to weeks)
- Vaginal irritation: the area "may become red and sore, and there may be a discharge" (American Cancer Society).
- Bladder and bowel: Cancer Research UK lists diarrhoea and bladder infections; burning or frequent urination is common after pelvic radiotherapy.
- Tiredness, nausea or diarrhoea are listed by Cleveland Clinic among general brachytherapy side effects, and are also common after pelvic chemoradiation.
Macmillan notes that these effects "usually improve over a few weeks or months after treatment finishes".
Longer-term effects
Radiotherapy can cause scar tissue in the vagina, making it shorter, narrower and less elastic (vaginal stenosis). This can make sex and internal examinations uncomfortable. Less often, late effects affect the bladder, bowel or rectum. In the large EMBRACE-I study (below), the five-year rate of severe (grade 3–5) late effects was 6.8% for the urinary tract, 8.5% for the bowel, 5.7% for the vagina and 3.2% for fistulae.
Vaginal dilators: what the evidence says
Many centres give you a set of dilators and advice to use them regularly after treatment, and the American Cancer Society notes stenosis "can be helped or prevented by stretching the walls of the vagina several times a week" with sex or a dilator. A Cochrane review (2014) found no randomised trials proving that routine dilation prevents stenosis, but observational studies link frequent dilation with less self-reported narrowing. In practice: follow your own centre's instructions on when to start and how often, and ask for a specialist nurse if dilators are difficult to use.
| Checklist after cervical brachytherapy | Why |
|---|---|
| Know who to call out of hours | For fever, heavy bleeding, inability to pass urine or uncontrolled pain. |
| Ask when and how to start dilators | Timing and frequency vary by centre. |
| Ask about sex and lubricants | Vaginal changes are common; practical advice is available. |
| Keep follow-up appointments | Examinations and scans check response and pick up late effects early. |
| Report new bladder or bowel symptoms, even months later | Late effects can appear long after treatment and many are treatable. |
What the evidence shows about image-guided brachytherapy
The largest prospective study of modern MRI-guided brachytherapy for cervical cancer is EMBRACE-I, published in The Lancet Oncology in 2021. It followed 1,341 patients from 24 centres in Europe, Asia and North America who had chemoradiotherapy followed by MRI-guided brachytherapy.
At a median follow-up of 51 months, the cancer was controlled at the site where it started (local control) in 92% of patients at five years. The authors describe the results as a benchmark for clinical practice. These are group figures from specialist centres taking part in a study — they do not predict any one person's outcome, which depends on stage, tumour type, response and general health.
Questions to ask your team
- Will I have HDR, PDR or LDR brachytherapy, and how many sessions?
- Will each session need a new applicator insertion, or will it stay in for more than one treatment?
- What anaesthetic or sedation do you use, and will I need to stay overnight?
- Will you use MRI or CT with the applicator in place to plan each treatment?
- Which applicator do you plan to use, and might I need interstitial needles?
- How will we keep the whole course within the recommended time?
- What side effects should I report straight away, and to whom?
- When should I start using dilators, and who can help if it is difficult?
For a fuller printable list, see our questions to ask before brachytherapy.
FAQ
How many sessions of brachytherapy are needed for cervical cancer?
It depends on the centre's schedule. Guidelines and hospital leaflets describe roughly 2 to 6 high-dose-rate sessions; the American Brachytherapy Society notes that 5 sessions of 6 Gy has been the most common US schedule, while Cancer Research UK describes up to 4 treatments. Low-dose-rate treatment is instead given over one stay of hours to a few days.
Is brachytherapy for cervical cancer painful?
The radiation itself is not felt. Applicators are placed under general or spinal (epidural) anaesthetic or sedation, and they can be uncomfortable while in place, so painkillers may be given. Afterwards some people have mild period-like cramps or slight bleeding. Tell your team if pain is not controlled.
Why is brachytherapy given after external radiotherapy and chemotherapy?
External beam radiotherapy with chemotherapy treats the pelvis and shrinks the tumour; brachytherapy then gives a high, focused dose to the cervix that external beams cannot safely reach alone. The American Brachytherapy Society recommends brachytherapy as part of curative treatment for locally advanced cervical cancer and completing the whole course in under 8 weeks.
Am I radioactive after cervical brachytherapy?
No. With high-dose-rate or pulsed-dose-rate treatment the source returns to the machine after each session. Cancer Research UK states that you are only radioactive while the treatment machine is switched on, so afterwards you are safe to be around everyone, including children.
Do I need to use vaginal dilators after brachytherapy?
Many centres recommend dilators to reduce narrowing of the vagina after pelvic radiotherapy. A 2014 Cochrane review found no randomised trials proving the benefit, but observational studies link regular dilation with less self-reported narrowing. Follow your own centre's advice on when to start and how often.
Sources
- American Cancer Society — Radiation Therapy for Cervical Cancer (accessed 9 October 2026)
- Macmillan Cancer Support — Radiotherapy for cervical cancer (accessed 9 October 2026)
- Macmillan Cancer Support — Internal radiotherapy (brachytherapy) (accessed 9 October 2026)
- Cancer Research UK — Internal radiotherapy (brachytherapy) for cervical cancer (accessed 9 October 2026)
- National Cancer Institute — Cervical Cancer Treatment (PDQ®), patient version (accessed 9 October 2026)
- RadiologyInfo.org (ACR/RSNA) — Brachytherapy (accessed 9 October 2026)
- Cleveland Clinic — Brachytherapy (accessed 9 October 2026)
- Viswanathan AN, Thomadsen B, et al. American Brachytherapy Society consensus guidelines for locally advanced carcinoma of the cervix. Part I: general principles. Brachytherapy. 2012;11(1):33-46 (accessed 9 October 2026)
- Viswanathan AN, Beriwal S, et al. ABS treatment recommendations for locally advanced carcinoma of the cervix. Part II: high-dose-rate brachytherapy. Brachytherapy. 2012;11(1):47-52 (accessed 9 October 2026)
- Haie-Meder C, et al. Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (I): concepts and terms in 3D image based treatment planning in cervix cancer brachytherapy. Radiother Oncol. 2005;74(3):235-245 (accessed 9 October 2026)
- ICRU Report 89: Prescribing, Recording, and Reporting Brachytherapy for Cancer of the Cervix. J ICRU. 2013;13(1-2) (accessed 9 October 2026)
- Pötter R, Tanderup K, et al. MRI-guided adaptive brachytherapy in locally advanced cervical cancer (EMBRACE-I): a multicentre prospective cohort study. Lancet Oncol. 2021;22(4):538-547 (accessed 9 October 2026)
- Miles T, Johnson N. Vaginal dilator therapy for women receiving pelvic radiotherapy. Cochrane Database Syst Rev. 2014;(9):CD007291 (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.