Hossam Donya

By Hossam Donya, Baljeet Seniwal, Reem Darwesh and Telma C.F. Fonseca

In this chapter, a detailed study on physics and methodology of small field dosimetry are reported. It introduces talking about how small radiation fields came into existence and the importance of accurate small-field dosimetry. In addition, it discusses small and long cavity theories for evaluating accurate dose response. It sheds the spot on pencil beam algorithms for evaluating dose response and uses Monte Carlo (MC) simulation in categorizing primary and scattering components of the radiotherapeutic photon beam. Moreover, it summarizes all commercial dosimeters used in small-field dosimetry. It gives good knowledge about detectors and equipment like ionization chambers for reference dosimetry in small and non-reference fields and different types of solid-state detector. The importance and applications of Monte Carlo techniques in small-field dosimetry and radiotherapeutic treatment methods based on small field are reported. For this purpose, different commonly used Monte Carlo codes are handled like Electron Gamma Shower (EGSnrc), Geant4, PENELOPE, and Monte Carlo N-Particle (MCNP). A review on the recent studies of using Monte Carlo simulation particularly on the small-field dosimetric studies is also reported. This chapter also discusses the recommendations of the code of practices (COPs) for dosimetry of small radiation fields. It mentions all recommendations provided by TRS-483 for accurate beam data collection and accurate dosimetric measurements. It gives good knowledge to the user for selecting a suitable dosimeter in small-field dosimetry through investigation of different practical methods and Monte Carlo simulations.

Part of the book: Theory, Application, and Implementation of Monte Carlo Method in Science and Technology

By Hossam Donya

Due to the risk of radiation exposure, radiation dosimetry is performed regularly to ensure the occupational safety of personnel and radiation workers. Therefore, various dosimeters are widely used to detect neutrons, gamma, X-ray, and proton irradiation fields. As an example, in medical applications, routine personal dosimetry is used to monitor and limit workers’ long-term occupational exposure. Radiation workers who undertake X-ray diagnostic, radiotherapy operations, in clinical and industrial application. Although, the overheads of running an in-house TLD (Thermoluminescent dosimetry) service for monitoring doses to eyes, pacemakers and so on seems rather high for the benefits conferred, however, it is still widely used for reporting doses accurately in various medical centers over the world. TLD also is widely used for measuring entrance doses on a handful of patients to validate a new LINAC/TPS combination. As well as in the industrial field as if petroleum, companies or nuclear reactor, RSO (radiation safety officer) used TLD badges to report delivered doses. In this chapter, we focus on the TLD technique for measuring doses of various ionizing radiation detection. Different methods for evaluations of TL Kinetics are covered. Modern TLD applications in the clinical field are also investigated. Some recommendations on advance dosimetry failure of TLD are concluded.

Part of the book: Dosimetry