Clinical feasibility of in-room proton radiography using single detector

Proton therapy is an advanced form of radiation therapy which is precisely targeted at a tumour with the ability to spare healthy tissue. This characteristic holds the potential of using protons for high-contrast radiographic images at a decreased dose when compared to conventional X-ray imaging. However, there is a lack of imaging techniques that would provide a direct information on the energy reduction of protons in the patient. Proton radiographic imaging hold the potential for this purpose.

The standard proton radiography involves the use of complicated and multiple detector placed before and after the object of interest. These measure the total energy and scattering angles of the protons going through and exiting the target.

In this thesis the performance of the proton energy resolved dose imaging (PERDi) using a single detector, which measures only the dE=dx of the emerging protons, is explored. A proton friendly 2D detector (Lynx, IBA dosimetry) is first evaluated. To do so, a calibration library in water was performed and three different configurations were imaged to determine the WET and RSP accuracy of the concept. Using this method has enabled to study to prove that the concept valid and to determine the WET and RSP of the imaged objects with an accuracy bellow 2mm and 2%, respectively.

After testing the performance of the method, another detector was exploited for proton radiographic images. The at-panel is a detector used daily in the clinical workflow of a patient's treatment. The purpose of this study is to demonstrate that one can use an existing imaging hardware to perform proton radiography at clinically acceptable imaging dose and achieving acceptable accuracies of water equivalent path lengths and tissue surrogate relative stopping powers. However, we found that the performance of the at-panel detector is not as good as the Lynx detector.

The study shows there is considerable promise for using proton radiography with a single layer detector. Further improvements need to be made before it can be used in a clinical environment. This method holds the potential of offering a reliable and inexpensive path to enable clinical proton imaging.