  We present a nitrogen-targeting-Proton-Carbon-Alpha-Therapy method,
abbreviated as Proton-CAT, which partially converts protons into carbon-12 and
$\alpha$ particles through nuclear reactions between protons and nitrogen-15.
Monte Carlo simulations validated the effectiveness of the Proton-CAT, and the
study specifically focused on the distribution of relative energy deposition.
The results indicated that the presence of nitrogen-15 enhanced the maximum
dose level of protons, resulting in more effective damage confined to tumor
cells. Statistical analysis of secondary ions has shown that the Proton-CAT
significantly increases the production efficiencies of carbon-12 and $\alpha$
particles. Furthermore, it has been revealed that elevating the nitrogen-15
concentration significantly boosts the dose of carbon and $\alpha$ particles
within the tumor region. The present work would contribute to the future
development of proton therapy.
