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Dosimetry for Cell Irradiation using Orthovoltage (40-300 kV) X-Ray Facilities
Published on: February 20, 2021
Response functions for computing absorbed dose to skeletal tissues from photon irradiation--an update
Perry B Johnson1, Amir A Bahadori, Keith F Eckerman
1Nuclear & Radiological Engineering, University of Florida, Gainesville, FL 32611, USA.
Physics in Medicine and Biology
|March 24, 2011
Summary
New photon dose response functions (DRFs) provide accurate radiation dose calculations for active and total shallow marrow across 32 bone sites. These findings improve skeletal dosimetry for radiation protection and medical applications.
Area of Science:
- Medical Physics
- Radiological Dosimetry
- Skeletal Tissue Radiation Biology
Background:
- Accurate dosimetry for radiosensitive skeletal tissues is crucial for radiation protection and medical applications.
- Existing photon fluence-to-dose response functions (DRFs) for skeletal tissues have limitations in scope and assumptions.
- The UF hybrid adult male phantom, based on micro-CT imaging, provides a detailed anatomical model for dosimetry calculations.
Purpose of the Study:
- To develop a comprehensive set of photon fluence-to-dose response functions (DRFs) for active and total shallow marrow at multiple skeletal sites.
- To calculate kerma coefficients, dose enhancement factors, and mass energy-absorption coefficient (MEAC) ratios for skeletal tissues.
- To validate the new DRFs by comparing derived quantities with established data from NIST and previous studies.
Main Methods:
- Development of DRFs using fractional skeletal masses and electron-absorbed fractions from the UF hybrid adult male phantom.
- Calculation of kerma coefficients for active marrow, inactive marrow, trabecular bone, and spongiosa assuming charged particle equilibrium above 200 keV.
- Derivation of dose enhancement factors and MEAC ratios by comparing kerma coefficients and DRF functions.
Main Results:
- A comprehensive set of DRFs was generated for active marrow (15 bone sites) and total shallow marrow (32 bone sites).
- Derived MEAC ratios showed excellent agreement with NIST data (0.8% mean difference).
- Dose enhancement factors for active marrow correlated well with shallow marrow volume fraction (R(2) = 0.91) and compared favorably with King and Spiers (1.9 percentage points mean absolute difference).
Conclusions:
- The new DRFs provide a significant advancement in skeletal dosimetry, particularly for total shallow marrow.
- The derived dose enhancement factors and MEAC ratios are validated against established data, enhancing confidence in their accuracy.
- These findings will improve internal dosimetry assessments in radiological protection and medical imaging.
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