EVOLUÇÃO HISTÓRICA DOS PROTOCOLOS DE DOSIMETRIA

• DOI: 10.22533/at.ed.4222312044

• Palavras-chave: -

• Keywords: -

• Abstract:

  Recommendations for the reference dosimetry of external beam radiotherapy have been issued since the 1960s by national and international organizations, usually under the name of dosimetry protocols and codes of practice (CoP). They include a description of the procedures to be followed for the specification of the quality of a clinical radiation beam and for the reference measurement with ionization chambers, including the necessary geometry arrangements for both type of measurements. Included also are the measurement equations to convert measured charge into absorbed dose in a given medium, referred to as the formalism of the protocol, as well as the required data for its implementation. Modern protocols are usually explicit in the details on the formalism and data, but it was not that way in the early days, as in some CoPs “little attempt is made to justify or explain the detailed background” (IAEA 1970); thus, many of the early recommendations were simply “cooking recipes” and their full understanding required consulting text books and dosimetry publications.

  Chronologically, dosimetry protocols can be grouped according to the quantity used to calibrate the user reference ionization chamber at the standards laboratory, namely, exposure, air kerma and absorbed dose to water. This text will review the most relevant publications following the grouping mentioned and, for sake of harmonization, the nomenclature, symbols and units will often be unified and converted into those used more recently by international organizations such as the International Commission on Radiation Units and Measurements (ICRU) and the International Atomic Energy Agency (IAEA). The focus will be on the formalisms and measurement equations for high-energy photon and electron beams, as together with the data provided, they are what most often differentiate one protocol within a given group from another.

• Número de páginas: 20