According to recent reports, there is an alarming reality in Vietnam today that about 90% of people have dental problems, mainly tooth decay. Dental diseases cause discomfort for patients and a loss of confidence in communication. Therefore, the demand for dental exams and treatments is increasing day by day.X-rays have long been used to treat dental diseases and are playing an increasingly important role in dentistry. The creation of cone-beam computer tomography (CTCB) has brought many benefits to users. This thesis mainly presents how to calculate the DAP number (Dose Area Product) at CTCB Orthophos and convert the unit of DAP (Gy.cm2) to the unit of the effective dose (mSv).The results obtained from nearly 100 CTCB scans show that the effective dose of the instrument Orthophos is about 0.2 mSv, which is satisfactory for the requirements for radiation safety even with the largest FOV.The study was carried out under the supervision of Denstply Sirona for the purpose of warning before taking, helping doctors (technicians) to manage the problems related to the imaging process and to minimize the radiation dose radiation on the patient, and determine the radiation on the patient in practice at the same time.

Proton therapy is one of the most accurate forms of cancer therapies, which requires accurate knowledge of the dose delivered to the patient and verification of the correct patient position with respect to the proton beam to avoid damage to critical normal tissues and geographical tumor misses. In existing proton treatment centers, dose calculation is performed based on X-ray computed tomography (CT), and the patient is positioned with x-ray radiographs. The use of X-ray CT images for proton treatment planning ignores fundamental differences in physical interaction processes between photons and protons and is therefore inherently inaccurate. Further, X-ray radiographs depict only skeletal structures; they do not show the tumor itself. Ideally, the image of the patient taken directly with proton CT by measuring the energy loss of high-energy protons that traverse the patient. The main content of this report is the application of simulation program PENH proton transmission via phantom associated with the PENEASY creation in proton imaging that can be applied in proton therapy.