Table 1 Dosimeter characteristics summary
From: Optical fibre sensors: their role in in vivo dosimetry for prostate cancer radiotherapy
Dosimeter | Advantages | Disadvantages | Characteristics |
|---|---|---|---|
Thermoluminescence dosimetry (TLD) | Used in Clinical QA dosimetry Linear from 0.01 Gy to 300 Gy Can be made small for point dose measurements Low cost and come in different sizes Monitors beta, gamma, X-ray and neutron radiations. Corrections for each type are needed | No real time measurement. Readout time can be consuming Supralinear from 300 Gy to 1 kGy TLD devices are re-useable but suffer from sensitivity with repeated use | Dose range: 0.10 mSv–10 Gy Energy response: Beta (MAX): 0.766 MeV–5 MeV, Photon: 5 keV–6 MeV, Neutron (TLD): Thermal–6 MeV, Neutron (CR39): 200 keV–6 MeV |
Plastic Scintillating fibre optic dosimeter | Little energy dependence Rapid measurement time of around 2 s Linear from 0.01 Gy to 1 kGy Small (1 × 1 × 0.2 cm3) Stable for days Reusable, re-readable (0.03 % signal loss over 190 readings. Can be optically reset using UV | Supralinear response >2 Gy Sensitivity to light and temperature during irradiation and readout Room temperature fading of the OSL signal. Only two materials are commercially used in OSL dosimetry:Al2O3:C and BeO | Useful from 0.01 Sv to 100 Sv for X-ray and gamma radiation |
Inorganic Scintillating fibre dosimeter | Used in radiotherapy type applications Can measure small volumes Long distance transmission, Immunity to electromagnetic interference | Effects of Cerenkov radiation Temperature dependent | Used for photon energies above 100 keV |
Phosphor coated fibre | Used in radiotherapy and low dose personnel dosimetry applications Low cost and easy manufacture High scintillation efficiency 3.23 % variation detected at 90 kV 50 μA Accuracy of 2 % found under 15 MV 100 MU radiotherapy testing | High radiation exposure (50 Gy to 500 Gy) induces significant permanent attenuation in plastic optical fibres | Range from 50 kV to 15MV X-ray |