PROTON BEAM AND PARTICLE THERAPY
THE MOST PRECISE RADIATION IN ONCOLOGY

Particle therapy uses beams of charged particles — most commonly protons, and for specific indications carbon ions — rather than X-rays. The key difference is the Bragg peak: charged particles deposit most of their energy at a specific, controllable depth in tissue and then stop, leaving no exit dose beyond the tumour.

• Proton Beam Therapy (PBT)

  The most widely used particle therapy. Protons are hydrogen nuclei. Over 100 operational centres worldwide. Evidence base spans multiple tumour types across hundreds of clinical studies. The most clinically established form of particle therapy.

• Carbon Ion Therapy (CIT)

  Uses carbon atom nuclei — much heavier than protons. Creates more intense ionization with oxygen-independent cell killing (high RBE). Particularly effective for radioresistant cancers: chordoma, chondrosarcoma, adenoid cystic carcinoma, salivary gland cancer. Available at SPHIC China, HIMAC Japan, HIT Germany.

• A Brief History

  Proton therapy proposed by physicist Robert Wilson in 1946; first patient treated at Lawrence Berkeley in 1954. First hospital-based centre opened at Loma Linda in 1990. Carbon ion therapy pioneered at HIMAC Japan from 1994. Now 100+ proton centres globally.

• Why Paediatrics Is the Most Important Application

  Children treated with radiation have decades of life ahead. Exit dose from conventional X-rays damages developing heart, lungs, bowel, and endocrine organs. Proton craniospinal irradiation reduces cardiac, pulmonary, and abdominal dose dramatically vs. photon — directly improving long-term health outcomes.

The Bragg peak is the fundamental physical phenomenon that distinguishes particle therapy from conventional radiation. Understanding it explains why particle therapy protects normal tissue in a way photons cannot.

“The Bragg peak is not a theoretical advantage — it is a measurable, reproducible physical phenomenon that reduces dose to critical normal structures in every patient treated.”

• How X-Rays (Photons) Behave

  X-rays enter the body, peak near the skin surface, then decline exponentially — but they pass through the patient completely. To deliver adequate dose to a deep tumour, significant dose is deposited both in front of (entry) and behind (exit) the tumour in normal tissue. IMRT distributes this exit dose across multiple beam paths, but cannot eliminate it.

• How Charged Particles Behave

  A proton or carbon ion loses energy slowly at first, then deposits a sharp peak of energy at a specific depth (controlled by initial beam energy) — and stops. No exit dose. Physicists position the Bragg peak precisely at the tumour by adjusting beam energy, and can spread it across the tumour volume using a spread-out Bragg peak (SOBP).

• Clinical Consequence: Normal Tissue Protection

  A proton beam to a brainstem tumour delivers full dose to the tumour and a dramatically reduced dose to the brainstem compared to photons. A proton craniospinal plan for medulloblastoma delivers full dose to the brain and spine while massively reducing cardiac, pulmonary, and abdominal dose — directly impacting outcomes for a child with 60+ years of life ahead.

Patient selection is central to evidence-based use of particle therapy. The benefit is greatest where normal tissue sparing is clinically meaningful and the tumour dose cannot be adequately delivered with conventional radiotherapy.

SPHIC (Shanghai) offers internationally comparable proton and carbon ion therapy at substantially lower cost. Carbon ion therapy is particularly more affordable in China and Japan than in European centres.

From eligibility assessment to treatment at SPHIC or partner particle therapy centres — end-to-end navigation.

1. 1

   Eligibility and Benefit Assessment

   Review of imaging, pathology, and prior treatment to determine whether particle therapy offers a meaningful dosimetric advantage over photon radiotherapy for the specific clinical situation — and whether the patients case justifies the cost and travel.

2. 2

   Centre Selection

   For most cases, SPHIC Shanghai (proton + carbon ion) is recommended. For specific paediatric indications or cases requiring carbon ion for radioresistant histology, alternative centres in Japan or Europe may also be appropriate.

3. 3

   Remote Physics Consultation

   SPHIC radiation oncologists and physicists can review imaging remotely to provide a treatment plan preview and dose comparison (proton vs. photon) before the patient commits to travel — confirming that particle therapy is the right choice.

4. 4

   Travel and Logistics

   Proton and carbon ion courses typically require 3–7 weeks in Shanghai depending on fractionation (conventional 20–35 fractions vs. hypofractionated 4–5 fraction courses for some indications). CancerFax arranges accommodation near SPHIC.

5. 5

   Treatment Records and Follow-Up

   Complete radiation treatment plan, dose-volume histograms, and follow-up schedule provided in translated form for the home radiation oncologist. Remote follow-up with SPHIC team coordinated at 3, 6, and 12 months.

Frequently Asked Questions