Browsing by Author "Myllymäki, Mila"

Radiation therapy is one of the key treatments for cancer, utilizing ionizing radiation to destroy cancer cells. Proton therapy uses high-energy proton beams since protons have a favorable depth-dose curve. Clinical proton beams must meet strict quality standards in order to maximise the efficacy of the treatment while ensuring the patient safety. Real-time knowledge of the beam’s intensity profile is essential for an accurate beam delivery. While gas-filled ionization chambers have traditionally been used as the standard beam monitor, the swift development of the beam delivery techniques demands for more accurate beam monitors. Semiconductor detectors potentially offer more accurate and efficient alternative for ionization chambers. In this study, the feasibility of using a silicon pixel detector in proton beams was investigated. The detector was originally designed for tracking minimum ionizing particles at the CMS experiment at CERN. Two experiments — one with an alpha source and one in a proton beam — were carried out to characterize the detector. The response to protons with different intensities and energies was investigated more closely in the proton beam. The results show that the detector response to different proton energies agrees with theoretical expectations. The saturation of the pixels limits measuring the full energy of the protons, however measuring the full energy is not essential in beam profile measurements. The detector also has a linear response to the beam intensity, although, the counting efficiency of the detector should be improved with new readout electronics. With different readout electronics, the detector might be a viable option for the beam profile measurements in clinical proton beams.