Development of proton CT imaging system using plastic scintillator and CCD camera

Area of Science:

• Medical Physics
• Radiological Imaging
• Particle Therapy

Background:

• Proton therapy requires accurate dose calculations, which depend on precise tissue density information.
• Current methods using x-ray CT (xCT) to Water-Equivalent Length (WEL) conversion introduce uncertainties in proton therapy planning.
• Proton computed tomography (pCT) offers a direct method to obtain WEL information, potentially improving accuracy.

Purpose of the Study:

• To construct and evaluate a proton computed tomography (pCT) imaging system.
• To assess the error in x-ray CT (xCT)-to-WEL conversion for proton therapy planning.
• To demonstrate the feasibility of pCT for imaging and its potential impact on treatment planning.

Main Methods:

• A pCT imaging system was designed utilizing a CCD camera to capture scintillation light along the proton beam path.
• A light-to-range conversion table was established to translate light intensity into proton range.
• Three-dimensional pCT images were reconstructed using experimental data from a 70 MeV proton beam.
• Image quality was assessed, including spatial resolution and evaluation of pixel values for various substances.

Main Results:

• The constructed pCT system successfully reconstructed three-dimensional images from experimental data.
• A thin structure of approximately 1 mm was clearly visualized.
• The spatial resolution of the pCT images was found to be comparable to that of xCT images.
• Investigation into image quality included assessment of pixel values and effects of multiple Coulomb scattering.

Conclusions:

• The developed pCT system demonstrates the capability for high-resolution imaging relevant to proton therapy.
• pCT offers a promising alternative for obtaining accurate WEL data, potentially reducing errors in proton therapy planning.
• Further investigation into image quality factors like scattering is warranted for clinical implementation.