Carbon loaded TLDs: Utility in radiotherapy
- Journal Title
- Radiation Measurements
- Publication Type
- Research article
- Abstract
- Background Thermoluminescence dosimetry (TLD) is a well-established dosimetric technique with large range of materials and sensitivities. To extend the use of TLD to surface dose measurements, carbon-loaded TLDs—commonly referred to as "black TLDs"—have been developed. The inclusion of carbon in the TLD matrix reduces the effective detector volume by limiting the emission of luminescence to a shallow surface layer, with the carbon concentration dictating the detection depth. Methods A set of 50 carbon-loaded LiF:Mg,Ti (RadPro) round chips (0.9 mm thick, 4.5 mm diameter) were commissioned using a programmable Lexsyg Smart reader suitable for thermos- and optically stimulated luminescence (OSL) dosimetry. Detection limit, dose response and reproducibility were determined and a correction for light emitted from the side wall of the TLD chips developed. The effective depth of measurement was determined in the build-up region of 6, 10 and 18 MV megavoltage photon beams (Varian Truebeam) in comparison with a thin window plane parallel ionisation chamber (IBA, advanced Markus type). Results The readout of the TLDs was reproducible within 1.9 % (2SD) and they showed typical supralinear response at doses exceeding 1 Gy. A correction applied for light emission from the side wall of the chips reduced the effective reading at the surface in MV X-rays to within 18 % of the dose measured with the ionisation chamber. Conclusion Mixing carbon with the active TL material creates an opportunity to restrict readout of dosimeters to regions of interest. There are several clinical applications that can benefit including in vivo dosimetry on patients’ skin, source strength verification for beta emitters and dosimetry in electronic brachytherapy.
- Publisher
- Elsevier
- Keywords
- Thermoluminescence dosimetry; Skin dose; Radiotherapy; Surface dose; In vivo dosimetry
- Department(s)
- Physical Sciences
- Publisher's Version
- https://doi.org/10.1016/j.radmeas.2026.107626
- Terms of Use/Rights Notice
- Refer to copyright notice on published article.
Creation Date: 2026-06-16 12:05:20
Last Modified: 2026-06-16 12:05:36