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RADIATION PROTECTION MEASUREMENTS WITH THE VARIANCE-COVARIANCE METHOD IN THE STRAY RADIATION FIELDS FROM PHOTON AND
J Lillhök1, L Persson1, C E Andersen2
1Swedish Radiation Safety Authority, Stockholm, Sweden.
Radiation Protection Dosimetry
|October 17, 2017
Summary
Stray radiation fields in photon and proton therapy were measured using microdosimetry. Results quantified absorbed dose and dose equivalent, crucial for patient safety and treatment planning.
Area of Science:
- Medical Physics
- Radiation Oncology
- Health Physics
Background:
- Understanding stray radiation is critical for radiation therapy safety.
- Photon and proton therapy facilities generate unique radiation fields.
- Accurate dosimetry is essential for minimizing unintended radiation exposure.
Purpose of the Study:
- To investigate stray radiation fields in photon and proton therapy.
- To quantify absorbed dose and dose equivalent in these environments.
- To assess the neutron component in proton therapy beams.
Main Methods:
- Microdosimetric variance-covariance method employed for stray radiation analysis.
- Two tissue-equivalent proportional counters (TEPCs) used for measurements.
- Monte Carlo simulations (MCNP6) utilized to study neutron components in proton beams.
Main Results:
- Photon beam stray absorbed dose: 0.3–2.4 μGy/MU; dose equivalent: 0.4–9 μSv/MU.
- Proton beam stray absorbed dose: 3–135 μGy/prescribed Gy.
- Variations depend on beam energy, measurement position, and detector characteristics.
Conclusions:
- Characterized stray radiation fields in clinical photon and proton therapy.
- Provided essential data for radiation protection and treatment optimization.
- Demonstrated the utility of microdosimetry for comprehensive radiation field assessment.
