What’s the difference between proton beam therapy and Gamma Knife?

What’s the difference between proton beam therapy and Gamma Knife?

September 24, 2025

Is proton therapy available in the UK?

September 28, 2024

If you or a loved one are exploring treatment options for a brain tumour or a neurological condition, you may have come across two specialist forms of radiotherapy: proton beam therapy and Gamma Knife radiosurgery.

Both are highly precise, non-invasive treatments that use radiation to destroy cancer cells or target abnormal tissue. But they work in different ways and are only appropriate in certain cases.

In this guide, we explain the key differences between Gamma Knife and proton beam therapy to help you make an informed decision about your treatment options.

For more information about private proton beam therapy, please do not hesitate to contact the friendly and experienced team at Proton International London.

What is Gamma Knife cancer treatment?

Gamma Knife is a specialist radiation therapy used to treat brain lesions, brain tumours and some neurological conditions. It is a ‘stereotactic radiosurgery’ technique, which delivers radiation to a single, precise target. Despite being called ‘surgery’, it is non-invasive and doesn’t involve a scalpel or incision.

By focusing radiation tightly on the tumour or lesion, Gamma Knife treatment minimises the dose received by surrounding healthy tissue.

It is often used to treat:

• Small brain tumours (benign or malignant)
• Arteriovenous malformations (AVMs)
• Acoustic neuromas (benign tumours arising from the vestibular nerve, which runs from the brain to the inner ear)
• Trigeminal neuralgia
• Some metastatic cancers to the brain

Treatment is often completed in a single session (sometimes more), and you can usually return home the same day.

How does Gamma Knife radiosurgery work?

Before treatment, MRI and/or CT scans are used to map the exact location of the tumour or abnormality. A multidisciplinary team, which may include a neurosurgeon, radiation oncologist, and medical physicist, uses the scans to plan the treatment with extreme precision.

The treatment works by directing hundreds of tiny gamma ray beams, each individually low in strength, from multiple angles towards the tumour. When these beams converge at a single, precisely defined point, they deliver a powerful dose of radiation. This level of precision allows for a maximum dose of radiation while limiting exposure to healthy brain tissue.

While receiving treatment, the patient wears a custom-made mask to keep the head safe and secure. The mask prevents even the slightest movement and helps deliver radiation directly where it needs to go.

Gamma Knife is a form of non-invasive treatment, meaning there is no incision, no general anaesthetic in most cases, and minimal recovery time. While effective, it is generally best suited to small, well-defined brain lesions.

What is Proton Beam Therapy?

Proton beam therapy (PBT) is another advanced form of radiation therapy. Whereas traditional radiation therapy uses photons, PBT uses protons. These tiny, positively charged particles release most of their energy at a specific point in the body, known as the Bragg peak, and then stop.

This is unlike traditional radiotherapy where radiation travels through the body, known as the ‘exit dose’. Proton beam treatment allows oncologists to deliver radiation directly to the tumour, with minimal damage to the surrounding tissue.

This precision is especially beneficial when tumours are located near critical structures, such as:

• The brainstem
• Optic nerves
• Spinal cord
• Inner ear
• Eyes

Proton beam therapy is usually delivered over multiple sessions (called fractions), over five to six weeks, depending on the tumour type, size, and location.

Can Proton Therapy and Gamma Knife treat the same conditions?

While the two therapies are used to treat cancer and lesions in the brain, they are not interchangeable. Each has advantages depending on the tumour’s size, location, and the overall goals of treatment.

Gamma Knife is usually best suited to:

• Small, well-defined tumours or abnormalities inside the brain, usually less than 3 cm in size
• Cases where the goal is to destroy the tumour or lesion in one go
• Cases where surgery isn’t suitable or possible

Proton beam therapy can be the more appropriate option when:

• The tumour is larger or less well-defined
• The tumour is close to very sensitive locations, which require protection
• A higher dose of radiation is needed to treat the tumour, and is more safely delivered in small, cumulative doses over several weeks (a process known as ‘fractionation’)

Key differences at a glance: Proton beam therapy vs Gamma Knife

Which radiation treatment is right for me?

The choice of Gamma Knife or proton beam therapy isn’t something you have to decide alone. Your clinical team will talk you through your options and recommend the safest and most effective for your individual diagnosis.

Their advice will be based on several factors, including:

• The type of tumour or condition you have, and where it’s located
• Whether it’s benign (non-cancerous) or malignant (cancerous)
• Its size, shape, and how close it is to important areas of the brain
• Your age, overall health, and what matters most to you in your treatment
• Whether a single session is likely to be effective, or if a longer course of treatment would offer better results

Expert guidance at Proton International London

At Proton International London, we provide private treatment for people across the UK and abroad. We use proton beam therapy to treat a range of cancers, particularly those located near vital structures or in sensitive areas of the body.

Researching cancer treatment for yourself or a loved one can be daunting, so we are here to support you and your family every step of the way. If you choose to make a referral, we will work closely with you and your existing clinical team to make a thorough assessment. Our multidisciplinary team, comprising globally recognised oncologists, will determine whether proton beam therapy is appropriate for your case.

If so, we will guide you through the process with calm, clarity and reassurance. From your first consultation through to aftercare, you can expect a personalised service from an attentive, genuinely caring team.

To ask us a question, please call 0203 9255 885. You can also explore our journal to learn more about the conditions we treat, the potential benefits of proton beam therapy, and other insights into advanced cancer care.

Frequently asked questions – What’s the difference between proton beam therapy and Gamma Knife?

Is Gamma Knife safe?

Yes, Gamma Knife radiosurgery is considered a safe and well-established treatment for certain brain conditions. It has been used for decades and is supported by extensive clinical research.

As with any medical treatment, there are some risks, including swelling, fatigue, or delayed effects, depending on the area treated. These will be discussed in detail with your care team before treatment.

Can children receive Gamma Knife treatment?

Gamma Knife can be used to treat certain brain tumours and conditions in children—but it’s not suitable for every case. It’s typically offered in specialist centres with experience in paediatric care, and used carefully and selectively.

Some children, particularly very young patients or those with larger tumours or growths near sensitive areas of the brain (such as the optic nerve or brainstem), may not be ideal candidates. In these situations, proton beam radiation therapy may be the safer option. Its ability to precisely target the tumour while sparing healthy, developing brain tissue makes it especially valuable in paediatric care.

When deciding on the most appropriate treatment, the care team will look closely at several important factors, including:

• Whether the child can remain still during treatment (some may require sedation or a general anaesthetic)
• The size and location of the lesion
• Long-term effects on developing brain tissue

The decision to use Gamma Knife therapy for children will be made by a multidisciplinary paediatric team, who will make their recommendation on the safest, most effective course of treatment.

Who is not a candidate for gamma knife surgery?

Gamma Knife may not be suitable for you if:

• Your tumour is large (typically over 3–4 cm in diameter)
• The tumour is near critical structures like the optic nerve or brainstem
• You require whole-brain radiation, not targeted treatment
• Your condition is outside the brain or skull base
• You can’t tolerate the use of an immobilisation mask (e.g., due to anxiety, age, or certain neurological conditions)
• You have serious underlying health issues that make the procedure unsafe

A specialist team will assess your case to determine the safest and most effective treatment option. If Gamma Knife isn’t appropriate, other advanced treatments, including proton beam therapy, may be considered.

Further reading:

• Proton beam therapy vs photon therapy