Spectral fiber dosimetry with beryllium oxide for quality assurance in hadron radiation therapy

Abstract

Using the radioluminescence light of solid state probes coupled to long and flexible fibers for dosimetry in radiotherapy offers many advantages in terms of probe size, robustness and cost efficiency. However, especially in hadron fields, radioluminophores exhibit quenching effects dependent on the linear energy transfer. This work describes the discovery of a spectral shift in the radioluminescence light of beryllium oxide in dependence on the residual range at therapeutic proton energies. A spectrally resolving measurement setup has been developed and tested in scanned proton fields. It is shown that such a system can not only quantitatively reconstruct the dose, but might also give information on the residual proton range at the point of measurement.

Comprehensive investigation of lateral dose profile and output factor measurements in small proton fields from different delivery techniques

“…In addition, they operated the detectors oriented perpendicular to the beam by which they were able to obtain even lower penumbras than those measured with the SFD diode indicating a much better resolution due to the small thickness of the diamond in that orientation (1 μm) 1 . Recently, spectral fiber dosimetry using beryllium oxide as radioluminescent material with high spatial resolution has been applied to acquire proton beam profiles and depth dose distributions 51 …”

“…1 Recently, spectral fiber dosimetry using beryllium oxide as radioluminescent material with high spatial resolution has been applied to acquire proton beam profiles and depth dose distributions. 51 In addition to films and scintillation screens, Task group 224 report 8 lists small point-like ionization chambers as suitable for scanned and scattered beam profile measurements. Although the maximum penumbra increase identified with such small ionization chambers in this work of 0.62 mm (Razor chamber) and 0.94 mm (PinPoint 3D) is within the tolerances for d 80/20 suggested in the Task group 224 report of ± 2 mm, this penumbra increase is still quite large with respect to the small field sizes investigated in this work.…”