"Brachytherapy or radiation?" is one of the most searched questions about this treatment — and it rests on a small misunderstanding. Brachytherapy is radiation therapy. The real comparison is between radiation delivered from inside the body and radiation delivered from outside it.
That difference changes the practical experience a great deal: the number of hospital visits, whether you need an anaesthetic, which tissues receive dose, and whether anything radioactive stays in your body. It also explains why, for cervical and many prostate cancers, teams use both.
Below we compare the two in one table, explain where SBRT and proton therapy fit (both are forms of external beam), and summarise what major guidelines say for prostate cancer — including what they do not establish. This is general information; the choice for any one person is made with their own team.
Is brachytherapy radiation therapy?
Yes. Brachytherapy is a type of radiation therapy in which a sealed radioactive source is placed inside the body, in or next to the tumour. The NHS describes it as small pieces of radioactive metal "(usually temporarily) placed inside your body near the cancer". The word comes from the Greek brachys, "short", because the radiation travels a short distance from the source. For a fuller introduction, see internal radiotherapy explained.
RadiologyInfo (ACR/RSNA) sums up the core difference from external beam treatment: brachytherapy "uses a higher total dose of radiation to treat a smaller area than external beam radiation therapy", which can help avoid delivering radiation to some surrounding organs.
How external beam radiotherapy works
In external beam radiation therapy, "a machine outside the body" aims radiation at the cancer, in the words of the US National Cancer Institute (NCI). The usual machine is a medical linear accelerator (linac), which RadiologyInfo describes as customising "high energy x-rays or electrons to conform to a tumor's shape". Older texts call this teletherapy ("therapy at a distance") — so "brachytherapy vs teletherapy" is the same comparison under older names.
A typical course looks like this, according to the NCI and NHS:
- Frequency: most people are treated "once a day, five days a week, Monday through Friday" (NCI), though some schedules differ.
- Length of course: depends on the type of cancer and other factors; for cervical cancer the American Cancer Society describes about 5 weeks.
- Each visit: the beam is on for about 1 to 5 minutes; the whole visit lasts 30 minutes to an hour, mostly spent positioning you (NCI).
- Feeling: the NHS says it "usually only takes a few minutes and is completely painless".
- Radioactivity: "External beam radiation therapy will not make you radioactive" (NCI).
The EBRT family: IMRT, IGRT, SBRT and protons
Several names you may hear are all external techniques. The NCI lists 3D conformal radiotherapy, intensity-modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT), proton therapy, stereotactic radiosurgery (SRS, for the brain) and stereotactic body radiation therapy (SBRT), which it describes as being for small, isolated tumours outside the brain and spinal cord, "usually given in up to five doses". So "brachytherapy vs SBRT" and "brachytherapy vs protons" are both versions of internal vs external.
Key differences table
| Brachytherapy (internal) | External beam (EBRT) | |
|---|---|---|
| Where the source is | Inside or next to the tumour, in seeds, needles, tubes or an applicator | In a machine (usually a linac) outside the body |
| Dose pattern | Higher total dose to a smaller area; steep fall-off around the source (RadiologyInfo) | Beams shaped to the target from several directions; can cover larger regions such as nearby lymph nodes |
| Number of visits | Usually a few: one implant for permanent seeds, or a handful of HDR sessions (see HDR vs LDR) | Usually daily on weekdays for several weeks (NCI); fewer with SBRT or hypofractionated schedules |
| Anaesthesia | Depends on site: general, spinal, sedation, or none (RadiologyInfo; Macmillan for prostate HDR) | Not needed; treatment is painless (NHS) |
| Hospital stay | None to a few days, depending on type | Normally outpatient |
| Radioactive afterwards? | No once a temporary source is removed; permanent seeds leave a low, fading source (NCI) | No (NCI, NHS) |
| Precautions around others | Only after permanent implants, for a limited time — see radiation precautions after going home | None |
| Typical sites mentioned by sources | Prostate, cervix and other gynaecological cancers (ACS, Macmillan), among others | Almost any site |
| Main limitation | Needs access to the tumour and suitable anatomy (e.g. ACS notes it may not work as well for large prostates) | More visits; dose passes through normal tissue on the way in |
When they are used together
In many treatment plans the question is not "which one" but "in what order". External beam radiotherapy treats the tumour and its surrounding region; brachytherapy then adds a concentrated extra dose — a boost — to the tumour itself.
Cervical cancer
The American Cancer Society states that "brachytherapy mainly is used in addition to EBRT as a part of the main treatment for cervical cancer". When EBRT is the main treatment it is usually combined with chemotherapy (often low-dose cisplatin), and brachytherapy may be given after the concurrent chemoradiation is complete. Our step-by-step guide to cervical cancer brachytherapy explains the applicators and sessions.
Prostate cancer
For prostate cancer, NICE (England) advises: "Consider brachytherapy in combination with external beam radiotherapy" for people with CPG 2, 3, 4 and 5 localised or locally advanced prostate cancer (recommendation 1.3.24). CPG is the Cambridge Prognostic Group, NICE's risk grouping from 1 (lowest) to 5 (highest). The ASCO/Cancer Care Ontario guideline similarly recommends offering a brachytherapy boost (LDR or HDR) to eligible intermediate- and high-risk patients having EBRT.
Prostate cancer: what the guidelines compare
Prostate cancer is where "brachytherapy vs EBRT" is most often asked, because both can be used alone in some situations. Here is what two major guidelines actually say:
| Situation | ASCO / Cancer Care Ontario (2017 update) | NICE NG131 (England) |
|---|---|---|
| Low risk, active treatment wanted | LDR brachytherapy alone, EBRT alone and/or radical prostatectomy should be offered to eligible patients | — |
| Low-intermediate risk | LDR brachytherapy alone may be offered as monotherapy | — |
| Intermediate risk having EBRT | Brachytherapy boost (LDR or HDR) should be offered to eligible patients | Consider brachytherapy combined with EBRT (CPG 2–5) |
| High risk having EBRT + hormone therapy | Brachytherapy boost (LDR or HDR) should be offered to eligible patients | Consider combination (CPG 2–5); do not offer brachytherapy alone for CPG 4 and 5 (1.3.25) |
| HDR alone, cesium-131 | No recommendation for or against | — |
"—" means the specific point is not addressed in the recommendation text we quote; it does not mean the option is excluded. Guidelines are updated; check the current versions linked below.
On side effects, the American Cancer Society reports that some studies suggest erectile dysfunction rates "might be lower after brachytherapy", while others find rates similar to EBRT or surgery. It also notes that men with existing urinary problems, or who have had a TURP, may have a higher risk of urinary side effects after brachytherapy. For the full patient pathway see what to expect with prostate brachytherapy.
Brachytherapy vs SBRT and vs proton therapy — what's known and not known
SBRT
SBRT shares one feature with HDR brachytherapy: a few large doses instead of many small ones. The difference is that SBRT is delivered from outside, without needles or an anaesthetic. For prostate cancer, the American Cancer Society says SBRT's main advantage over IMRT is that treatment takes fewer days, and that it "can control the cancer about as well as IMRT". The sources we reviewed do not establish whether SBRT or brachytherapy is better for any group of patients, so this remains a conversation to have with your oncologist.
Proton therapy
Proton therapy is external beam radiotherapy using protons, which the NCI explains stop at the tumour rather than passing beyond it; it notes that high cost and machine size limit its use. For prostate cancer, the American Cancer Society says "most studies have found no difference in side effects or cancer control between proton beam therapy and IMRT", and that availability and insurance coverage vary. The NCI's patient summary of prostate cancer treatment lists proton beam therapy among treatments being studied in clinical trials. We found no guideline in our sources that ranks protons against brachytherapy.
| Brachytherapy | Standard EBRT (IMRT) | SBRT | Proton therapy | |
|---|---|---|---|---|
| Internal or external? | Internal | External | External | External |
| Typical number of treatments | One implant or a few sessions | Daily on weekdays for weeks | Usually up to five (NCI) | Varies by schedule |
| Needles or applicator? | Yes | No | No | No |
| Availability | Specialist centres | Widely available | Many centres | Limited (NCI, ACS) |
Why the choice is made by a multidisciplinary team
Choosing between internal radiation, external radiation, both, or another treatment such as surgery depends on details no general article can weigh: the tumour's stage and grade, its exact location, your anatomy (for example prostate size), bladder and bowel function, previous operations, your preferences about anaesthesia and visits, and the techniques your centre can deliver well.
That is why the decision is usually made by a multidisciplinary team — radiation oncologists, surgeons, medical physicists, specialist nurses and others — and then discussed with you. If brachytherapy is not offered locally, it is reasonable to ask whether referral elsewhere would change your options.
Questions to ask your radiation oncologist
- Is brachytherapy, external beam radiotherapy, or both being recommended for me — and why?
- If both, in what order, and how many visits will each part need?
- Would SBRT, protons or surgery be reasonable alternatives in my case? What would change?
- Which side effects differ between the options for me, and in which time frame (weeks vs years)?
- Does this centre offer HDR, LDR or both? How many brachytherapy procedures does it perform?
- Which guideline is my recommendation based on, and does my case fit it?
For a complete printable list, use our questions to ask your radiation oncologist checklist, and if brachytherapy is planned, read whether it will be HDR or LDR.
FAQ
Is brachytherapy a type of radiation therapy?
Yes. Brachytherapy is internal radiation therapy: a sealed radioactive source is placed inside or next to the tumour. External beam radiation therapy is the other main type, where a machine outside the body aims beams at the cancer.
Is brachytherapy better than external beam radiation?
Not in general. They suit different situations and are often used together. Brachytherapy concentrates a high dose in a small area, while external beam radiotherapy can treat larger regions such as nearby lymph nodes. For prostate cancer, guidelines from NICE and ASCO/Cancer Care Ontario describe when each, or both combined, may be offered.
Will I be radioactive after external beam radiation?
No. The US National Cancer Institute and the NHS both state that external beam radiotherapy does not make you radioactive. After brachytherapy, you are not radioactive once a temporary source is removed; only permanent seed implants leave a low, fading source in the body.
Why would brachytherapy and external beam radiotherapy be combined?
External beam radiotherapy treats the tumour and surrounding area, and brachytherapy then adds a concentrated extra dose, called a boost, to the tumour itself. The American Cancer Society says brachytherapy is mainly used in addition to external beam radiotherapy for cervical cancer, and prostate guidelines recommend a brachytherapy boost for some intermediate- and high-risk cases.
Is SBRT the same as brachytherapy?
No. Stereotactic body radiation therapy (SBRT) is a form of external beam radiotherapy that gives large, precisely shaped doses in a small number of sessions, usually up to five according to the National Cancer Institute. Brachytherapy places the source inside the body.
Sources
- National Cancer Institute — External Beam Radiation Therapy for Cancer (accessed 9 October 2026)
- National Cancer Institute — Brachytherapy to Treat Cancer (accessed 9 October 2026)
- National Cancer Institute — Prostate Cancer Treatment (PDQ®), patient version (accessed 9 October 2026)
- RadiologyInfo.org (ACR/RSNA) — Brachytherapy (accessed 9 October 2026)
- RadiologyInfo.org (ACR/RSNA) — Linear Accelerator (accessed 9 October 2026)
- NHS — Radiotherapy: what happens (accessed 9 October 2026)
- NICE — Prostate cancer: diagnosis and management (NG131), Recommendations (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)
- American Cancer Society — Radiation Therapy for Prostate Cancer (accessed 9 October 2026)
- American Cancer Society — Radiation Therapy for Cervical Cancer (accessed 9 October 2026)
- Macmillan Cancer Support — Internal radiotherapy (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.