Published on 28 Oct 2025
Step-and-Shoot spot-scanning proton arc therapy (SPArc) has been used for the first time to treat adenoid cystic carcinoma, a head and neck tumour.
SPArc is an advanced form of proton therapy, a type of radiation treatment that uses protons instead of X-rays to treat cancer.
It is especially useful for treating hard-to-reach or sensitive areas, such as head and neck tumors and works by targeting tumours with protons while sparing surrounding tissue.
The SPArc methods reduced radiation delivered to the brainstem (by 10%), optic chiasm (56%), oral cavity (72%), and spinal canal (90%) over other techniques.
The treatment used a computer program that mapped all spots and energy levels where proton beams could be delivered.
An energy layer refers to a specific depth in the body that receives proton beams of a particular energy—higher energy reaches deeper tissue, while lower energy treats shallower areas.
The machine scans and delivers radiation to multiple spots within one energy layer, then switches to the next energy level to target deeper tissue, gradually “painting” the entire tumour with precise, controlled doses.
Advanced Proton Therapy
Proton
SPArc
proton therapy
Diseases
cancer
Disease treatment
neck tumour