This revised edition of the IAEA TRS-398 Code of Practice fulfills the need for a systematic and internationally unified approach to the calibration of ionization chambers in terms of absorbed dose to water and to the use of these detectors in determining the absorbed dose to water for the radiation beams used in radiotherapy. It is based on new key data for radiation dosimetry published by the International Commission on Radiation Units and Measurements (ICRU). It contains updated information on new commercially available ionization chambers and addresses the needs of professionals working with newer radiotherapy technologies.

• 1. INTRODUCTION
  • 1.1. Background
    • 1.1.1. ICRU Key data for radiation dosimetry
  • 1.2. Objective
    • 1.2.1. Motivation for updating the international code of practice for dosimetry based on standards of absorbed dose to water
    • 1.2.2. Advantages of an international code of practice based on standards of absorbed dose to water
    • 1.2.3. Concluding remarks
  • 1.3. Scope
  • 1.4. Structure
    • 1.4.1. Range of beam qualities
    • 1.4.2. Practical use of the international code of practice
    • 1.4.3. Expression of uncertainties
    • 1.4.4. Quantities and symbols
• 2. FRAMEWORK
  • 2.1. The international measurement system
    • 2.1.1. The mutual recognition arrangement of the International Committee for Weights and Measures
    • 2.1.2. The IAEA/WHO network of Secondary Standards Dosimetry Laboratories
  • 2.2. Standards for absorbed dose to water
• 3. ND,W BASED FORMALISM
  • 3.1. Formalism
    • 3.1.1. Reference conditions
    • 3.1.2. Influence quantities
  • 3.2. Correction for the radiation quality of the beam, kQ,Qₒ
    • 3.2.1. The concept of the intermediate quality Qint and its use for photon beams
    • 3.2.2. The intermediate quality for electron beams
    • 3.2.3. The intermediate quality to convert between modalities
• 4. IMPLEMENTATION
  • 4.1. General
    • 4.1.1. Calibrations in standards laboratories made at multiple beam qualities
    • 4.1.2. Calibrations in standards laboratories made at a single reference quality Qo
    • 4.1.3. Recommendations
  • 4.2. Equipment
    • 4.2.1. Ionization chambers
    • 4.2.2. Measuring assembly
    • 4.2.3. Phantoms
    • 4.2.4. Waterproof sleeve for the chamber
    • 4.2.5. Positioning of ionization chambers at the reference depth
  • 4.3. Calibration of ionization chambers
    • 4.3.1. Calibration in a 60Co beam
    • 4.3.2. Calibration in kilovoltage X rays
    • 4.3.3. Calibration at other qualities
  • 4.4. Reference dosimetry in the user beam
    • 4.4.1. Determination of the absorbed dose to water
    • 4.4.2. Practical considerations for measurements in the user beam
    • 4.4.3. Correction for influence quantities
  • 4.5. Cross-calibration of ionization chambers
    • 4.5.1. Cross-calibration in the reference beam Qo
    • 4.5.2. Cross-calibration in a beam Qcross other than the reference beam Qo
    • 4.5.3. Use of a cross-calibrated chamber
• 5. CODE OF PRACTICE FOR 60CO GAMMA RAY BEAMS
  • 5.1. General
  • 5.2. Dosimetry equipment
    • 5.2.1. Ionization chambers
    • 5.2.2. Phantoms and chamber sleeves
  • 5.3. Beam quality specification
  • 5.4. Determination of absorbed dose to water
    • 5.4.1. Reference conditions
    • 5.4.2. Determination of absorbed dose under reference conditions
    • 5.4.3. Absorbed dose at zmax
  • 5.5. Cross-calibration of field ionization chambers
  • 5.6. Measurements under non-reference conditions
    • 5.6.1. Central axis depth dose distributions
    • 5.6.2. Field output factors
  • 5.7. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
• 6. CODE OF PRACTICE FOR HIGH ENERGY PHOTON BEAMS
  • 6.1. General
  • 6.2. Dosimetry equipment
    • 6.2.1. Ionization chambers
    • 6.2.2. Phantoms and chamber sleeves
  • 6.3. Beam quality specification
    • 6.3.1. Choice of beam quality index
    • 6.3.2. Measurement of beam quality index
  • 6.4. Determination of absorbed dose to water
    • 6.4.1. Reference conditions
    • 6.4.2. Determination of absorbed dose under reference conditions
    • 6.4.3. Absorbed dose at zmax
  • 6.5. Values for
    • 6.5.1. Chamber calibrated in 60Co
    • 6.5.2. Chamber calibrated in a series of high energy photon beam qualities
    • 6.5.3. Chamber calibrated at Qo with generic experimental values
  • 6.6. Cross-calibration of field ionization chambers
  • 6.7. Measurements under non-reference conditions
    • 6.7.1. Central axis depth dose distributions
    • 6.7.2. Field output factors
  • 6.8. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
• 7. CODE OF PRACTICE FOR HIGH ENERGY ELECTRON BEAMS
  • 7.1. General
  • 7.2. Dosimetry equipment
    • 7.2.1. Ionization chambers
    • 7.2.2. Phantoms and chamber sleeves
  • 7.3. Beam quality specification
    • 7.3.1. Choice of beam quality index
    • 7.3.2. Measurement of beam quality
  • 7.4. Determination of absorbed dose to water
    • 7.4.1. Determination of absorbed dose under reference conditions
    • 7.4.2. Reference conditions
    • 7.4.3. Absorbed dose at zmax
  • 7.5. Values for
    • 7.5.1. Chamber calibrated in 60Co
    • 7.5.2. Chamber calibrated at a series of electron beam qualities
  • 7.6. Cross-calibration of ionization chambers
    • 7.6.1. Cross-calibration procedure
    • 7.6.2. Subsequent use of a cross-calibrated chamber
  • 7.7. Measurements under non-reference conditions
    • 7.7.1. Central axis depth dose distributions
    • 7.7.2. Field output factors
  • 7.8. Use of plastic phantoms
    • 7.8.1. Scaling of depths
    • 7.8.2. Plastic phantoms for beam quality specification
  • 7.9. Non-standard electron beams
  • 7.10. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
• 8. CODE OF PRACTICE FOR LOW ENERGY KILOVOLTAGE X RAY BEAMS
  • 8.1. General
  • 8.2. Dosimetry equipment
    • 8.2.1. Ionization chambers
    • 8.2.2. Phantoms
  • 8.3. Beam quality specification
    • 8.3.1. Choice of beam quality index
    • 8.3.2. Measurement of beam quality
  • 8.4. Determination of absorbed dose to water
    • 8.4.1. In-air method
    • 8.4.2. In-phantom method
  • 8.5. Measurements under non-reference conditions
    • 8.5.1. Central axis depth dose distributions
    • 8.5.2. Field output factors
  • 8.6. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
• 9. CODE OF PRACTICE FOR medium energy KILOVOLTAGE X ray BEAMs
  • 9.1. General
  • 9.2. Dosimetry equipment
    • 9.2.1. Ionization chambers
    • 9.2.2. Phantoms and chamber sleeves
  • 9.3. Beam quality specification
    • 9.3.1. Choice of beam quality index
    • 9.3.2. Determination of beam quality
  • 9.4. Determination of absorbed dose to water
    • 9.4.1. Reference conditions
    • 9.4.2. Determination of absorbed dose under reference conditions
    • 9.4.3. Chamber calibrated in terms of air kerma free in air
    • 9.4.4. Chamber calibrated in terms of absorbed dose to water
  • 9.5. Measurements under non-reference conditions
    • 9.5.1. Central axis depth dose distributions
    • 9.5.2. Field output factors
  • 9.6. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
• 10. CODE OF PRACTICE FOR PROTON BEAMS
  • 10.1. General
  • 10.2. Dosimetry equipment
    • 10.2.1. Ionization chambers
    • 10.2.2. Phantoms and chamber sleeves
  • 10.3. Beam quality specification
    • 10.3.1. Choice of beam quality index
    • 10.3.2. Measurement of beam quality
  • 10.4. Determination of absorbed dose to water
    • 10.4.1. Reference conditions
    • 10.4.2. Determination of absorbed dose under reference conditions
    • 10.4.3. Recombination corrections
  • 10.5. Values for
  • 10.6. Cross-calibration of ionization chambers
    • 10.6.1. Cross-calibration procedure
    • 10.6.2. Subsequent use of a cross-calibrated chamber
  • 10.7. Measurements under non-reference conditions
    • 10.7.1. Central axis depth dose distributions
    • 10.7.2. Field output factors
    • 10.7.3. Use of plastic phantoms for relative dosimetry
  • 10.8. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
• 11. CODE OF PRACTICE FOR LIGHT ION BEAMS
  • 11.1. General
  • 11.2. Dosimetry equipment
    • 11.2.1. Ionization chambers
    • 11.2.2. Phantoms and chamber sleeves
  • 11.3. Beam quality specification
  • 11.4. Determination of absorbed dose to water
    • 11.4.1. Reference conditions
    • 11.4.2. Determination of absorbed dose under reference conditions
    • 11.4.3. Recombination correction in light ion beams
  • 11.5. Values for
  • 11.6. Measurements under non-reference conditions
  • 11.7. Estimated uncertainty in the determination of absorbed dose to water under reference conditions
  • 11.8. Worksheet
• Appendix I FORMALISM FOR THE DOSIMETRY OF KILOVOLTAGE X RAY BEAMS
• Appendix II DETERMINATION OF AND ITS UNCERTAINTY
• Appendix III BEAM QUALITY SPECIFICATION
• Appendix IV EXPRESSION OF UNCERTAINTIES
• REFERENCES
• ABBREVIATIONS
• CONTRIBUTORS TO DRAFTING AND REVIEW