The effect of fluorescence on surface dose with superficial X-rays incident on tissue with underlying lead
| Autor: | Millicent Chan, John Baines, Sylwia Zawlodzka, Tim Markwell |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Backscatter medicine.medical_treatment Monte Carlo method Biomedical Engineering Biophysics General Physics and Astronomy Molecular physics Spectral line Imaging phantom Fluorescence 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine medicine Radiology Nuclear Medicine and imaging Computer Simulation Phantoms Imaging X-Rays Dose-Response Relationship Radiation Organ Specificity 030220 oncology & carcinogenesis Laser beam quality Superficial X-rays Monte Carlo Method Beam (structure) |
| Zdroj: | Australasian physicalengineering sciences in medicine. 42(1) |
| ISSN: | 1879-5447 |
| Popis: | An Advanced Markus chamber on the surface of solid water phantom was used to determine surface dose reduction, with either a lead or air interface, as a function of surface-interface separation (t). The beam quality dependence of dose reduction was investigated using the 50 kV, 100 kV and 150 kV beams of an Xstrahl 150 superficial X-ray unit. For each beam the dose correction factor, DCF(t), namely the ratio of surface dose (t) to surface dose (t = 100 mm), was determined. Monte Carlo simulations of DCF(t) with a lead interface were compared with corresponding measured values. Simulated spectra were calculated at the phantom surface for full backscatter (t = 100 mm) and with either a lead or air interface at 2 mm or 8 mm depth. For each depth and beam quality lead fluorescent radiation at the surface was evident. The variation of DCF(t) for each beam and field size exhibits a minima at t ≈ 5 mm and in the range 1 mm ≤ t ≤ 40 mm surface dose reduction is larger for 100 kV than 150 kV. Monte Carlo simulated DCF(t) are consistent with corresponding measured DCF(t). From simulated spectra L-series fluorescent X-rays (≈ 15 keV) emanating from lead at t = 2 mm are evident for all beams and fluorescent K-series X-rays only occur with 100 kV and 150 kV beams. |
| Databáze: | OpenAIRE |
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