MEDICAL PHYSICS

Academic Year 2022/2023 - Teacher: GIUSEPPE ANTONIO PABLO CIRRONE

Expected Learning Outcomes

The main elements in the course are basic interaction mechanisms between ionizing radiation and matter and the theoretical basis for dosimetry for the use in radiotherapy and risk assessment of radiation exposure of humans. Important topics are Interaction cross-sections (classical), mechanisms for the interaction of photons, neutrons and charged particles, fundamental entities in dosimetry, cavity theories, radiation equilibrium, applied dosimetry in radiation-based medical diagnostics and therapy, neutron dosimetry, detectors for dosimetry.

The specific learning objectives of this course are:

  1. Understand the basis of the new Italian laws regulating the activities of the Medical Physicist and of the Radioprotection expert
  2. Understand the connections between the physics laws and their use in Medicine;
  3. Understanding the role of the Medical physicist and the Researcher in the field of the Medical Physics 
  4. Understanding the theoretical basis of the radiation dosimetry
  5. Understanding the main characteristics of a dosimetric system and the concepts connected with the absolute dosimetry of an ionising radiation
  6. Understanding the main characteristics of a detector for the dose measurement
  7. Giving to the student an overview of the quality control procedures on the radiation machines and of the Medical Physics roles
  8. Analise and understand the International Code of Practice for the absolute dose measurements of ionising radiation (gamma, proton, ions)
  9. Understanding the main concepts of the microdosimetry and their connection with the modern radiotherapy and radiobiology

Moreover, as recommended by the "Dublino descriptors" this class will permit to acquire the following transversal competences:

Knowledge and ability of understanding

  • Critical understanding of the last advances in modern Physics and their interconnection with particular care towards the interdisciplinary physics
  • Ability to understanding the relationship between the radiation interaction with matter and its biological effects
  • Knowledge of the basis of radiation dosimetry
  • Understanding the role of the radiation detector in dosimetry
  • Ability in measure and analyse a ionising radiation determining its main characteristics for their application in Medical Physics
  • Develop a multidisciplinary ability understanding the connection between Nuclear Pysics, detectors technology, Biology 

Ability into applying the received knowledge

  • Ability into applying the received knowledge using a rigorous scientific method
  • Ability into realising very simple experiments in the field of interest of the Medical Physics and into analysing the acquired data
  • Ability into qualitatively understand the effects of ionising radiations of different characteristics 
  • Ability to use programming languages for the study and interpretation of acquired data 

Autonomy of judgment

  • The student will be able to understand the relationship between the concept of energy release in mater with those of dosimetry and microdosimetry and with observed biological effects
  • The student will be able to find the most appropriate methods to analyse the experimental data e the discussed concepts

Communicative ability:

  • The student will be able to understand a scientific paper on one of the argument discussed during the class: he will make a talk illustrating the paper content and making a critic analysis

Course Structure

The classes will be in the English language.

Teaching will consist of a combination of classroom lectures, electronic lectures/tasks, calculations and group tasks with a set of experimental activities that will be organised in the laboratory.

The experimental activity will deal with:

  • The measure of dose from a natural source with an absolute ionisation chamber
  • The measure of microdosimetric spectra with a solid-state detector
  • The measure of a gamma spectra emitted by a natural source with a Gernanium detector
  • The analysis of a plastic detector irradiated with ion beams
  • [Other experimental activities could be added depending on time disposal]

Moreover, we can discuss additional activities on medical physics experiments may be of interest

Should the circumstances require online or blended teaching, appropriate modifications to what is hereby stated may be introduced, in order to achieve the main objectives of the course.

Detailed Course Content

  1. Radiation to matter interaction
    1. General on the interaction of the ionising radiation with matter
    2. Interaction between photons, electrons and charged particles with matter
    3. The principles of the energy transfer to the matter and their connection with the absorbed dose and the Medical Physics applications
    4. Stochastic and non-stochastic processes 
       
  2. Generation and use of the X-ray radiation
    1. ‚ÄčFunctioning principles of an X-Ray tube
    2. Physics and dosimetric properties of an X-Ray beam
  3. General concepts on imaging and its quality in diagnostic radiology 
     
  4. Radiotherapy
    1. general concepts
    2. Innovative approaches in radiotherapy
    3. The "FLASH" radiotherapy: biological evidences and dosimetric approaches
       
  5. Radiation dosimetry
    1. Quantities for describing the interaction of ionizing radiation with matter
      1. Exposure
      2. Compared examples of energy imparted, the energy transferred and net energy transferred
      3. Absorbed dose for direct and direct ionization radiation
      4. KERMA to energy fluence, dose and exposure relation for photon and neutron beams
      5. KERMA
      6. Charged-particle and radiation equilibria
        1. Radiation equilibrium
        2. Charged particle equilibrium
        3. Use of the charged particle equilibrium in the measure of exposition
        4. The relation between absorbed dose and exposure
        5. Cases of the charged particle equilibrium failure
        6. Transient charged particle equilibrium
           
  6. The cavity theory
    1. Bragg-Gray theory
    2. Spencer’s derivation of the Bragg-Gray theory
    3. Averaging stopping powers
    4. Spencer and Burlin cavity theory
    5. The Fano theorem
    6. Calculation of the absorbed dose for charged particle beams
      1. Dose in thin foils
      2. Mean dose in thicker foils
      3. Contribute of the electron backscattering
      4. Dose versus depth relation
         
  7. Dosimetry fundamentals
    1. Concepts of radiation dosimetry and dosimeter
    2. Interpretation of a dosimetric measure
    3. General characteristics of a dosimeter
    4. The most common dosimetric systems
      1. The ionisation chamber
      2. Active and passive solid-state detectors
      3. New dosimeters for the relative and absolute dosimetry
         
  8. The ionization chambers in radiological dosimetry
    1. Cavity ionization chamber
    2. Charge and current measurements
    3. Ionisation and excitation
    4. Ion-chamber saturation and ionic recombination effects
       
  9. Code of practices for absolute dosimetry measurement for clinical applications
    1. Formalism
    2. Implementation
    3. Equipment
    4. Calibration of the ionisation chambers
       
  10. Dosimetry of a clinical proton and ion beams
    1. General
    2. Dosimetry equipment
      1. Ionisation chambers
      2. Phantoms
    3.  Beam quality specifications
    4. Determination of absorbed dose to water
    5. Reference dosimetry in the User beam
       
  11. Microdosimetry
    1. What is microdosimetry
    2. Examples of the need of microdosimetry
    3. Stochastic and non-stochastic quantities and connection between microdosimetry and dosimetry
    4. Main approaches to microdosimetry
    5. LET distributions and their limitations
    6. Connection of LET with the biological damage
    7. Radial profile approach
      1. Track structure simulation approach
      2. Proportional counters microdosimetry
      3. Track structure simulations

Textbook Information

  1. F.H. Attix - Introduction to radiological physics and radiation dosimetry, Wiley-VCH Verlag edition

  2. H. Johns and J. R. Cunninghan - The physics of radiology - Charles Thomas publisher

  3. G.F.Knoll - Radiation detection and measurements - John Wiley & Sons, Inc.

  4. Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water

  5. TECHNICAL REPORTS SERIES No. 398 INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 2000


Course Planning

 SubjectsText References
1Basic of generation of ionising radiation G. Knoll and FH Attix
2Basic of the interaction of ionising radiation with matter G. Knoll and FH Attix
3Radiation dosimetry quantities and units FH Attix and h Johns J.R. Cunninghan
4Charged particle and radiation equilibria FH Attix and h Johns J.R. Cunninghan
5The Cavity theory FH Attix and h Johns J.R. Cunninghan
6Dosimetry fundamentals FH Attix and h Johns J.R. Cunninghan
7Dosimetric protocolsIAEA TRS 398 International Code of Practice
8New Italian regulamentation for the patient and employers radioprotectionDECRETO LEGISLATIVO 31 luglio 2020, n. 101