Tm Phosphors Research Articles

Characteristics of the Panasonic UD-802 Phosphors

Several basic dosimetric characteristics of Li 2 B 4 O 7 :Cu and CaSO 4 :Tm phosphors in Panasonic UD-802 dosemeters were measured

Heavy Particle Dosimetry with High Temperature Peaks of CaF2:Tm and 7LiF Phosphors

Heavy Particle Dosimetry with High Temperature Peaks of CaF2:Tm and 7LiF Phosphors

In vivo dosimetry in the pelvis during fast neutron therapy.

The assessment of dose distributions in patients during treatment with fast neutrons is based on measurements in a phantom material, i.e. water or another type of tissue equivalent (TE) liquid. Only limited information is available on fast neutron dosimetry in vivo in order to check how well these phantom materials simulate the average density and composition of the human body in the irradiated area. At Hammersmith Hospital, in-vivo dosimetry has been applied to check the dose in the oesophagus as well as the exit dose during irradiation of carcinoma of the bronchus (Field, 1971). Activation of small pellets of aluminium and measurement of the induced 27Mg activity was the technique used. More recently the application of CaSO4: Tm phosphor TLD (Blum et al., 1976) and the activation of indium (Catterall and Bewley, 1979) have been described for dosimetry during neutron therapy in that institute. Smith et al. (1976) inserted silicon diodes into the oesophagus to measure the effect of intervening lung tissue...

Ultraviolet dosimetry using intrinsic thermoluminescence in CaSO 4:Tm

While there is no appreciable difference in the γ-ray sensitivities of CaSO 4:Tm and CaSO 4:Dy TL phosphors their intrinsic u.v. sensitivities were found to be in the ratio of 60:1 respectively. The T max of the glow curves for the u.v. and γ-exposed CaSO 4:Tm phosphors were found to occur at 205 and 230°C respectively. The glow curve shape remained the same for γ-doses in the range 10 −4−10 0 Gy. The glow curve however broadened on the high temperature side with increasing u.v. exposures. The TL response of CaSO 4:Tm was studied as a function of u.v. exposure in the range 1−10 4 J m −2. The stability of u.v. induced TL in CaSO 4:Tm at room temperature was studied for various periods of time.

Calcium sulphate phosphor for clinical neutron dosimetry.

CaSO4: Tm phosphor TLD has been used, mixed with glucose, to measure neutron and gamma doses separately. The results of measurements taken on 50 patients undergoing clinical neutron therapy are reported. Comparisons with isodose estimations at entrance and exit points give standard deviations of 8.8 and 17 % respectively. An analysis of the errors involved indicates that the energy sensitivity of the system is a problem, but the results obtained are encouraging enough to continue development of a system for measuring doses in the treated volume.

Thermally stimulated luminescence and infrared studies of CaS : Bi, Tm phosphors

Calcium sulphide phosphors doped with bismuth and thulium are prepared from Indian minerals. The glow curves are recorded in the temperature range of 96–320 °K. The activation energies are determined by analyzing the glow peaks after thermal cleaning, using different methods. The results show that, in these phosphors, the electron traps responsible for thermoluminescence are present prior to irradiation. The infrared absorption spectra are recorded in the range of 4000-250 cm -1. It is concluded that the traps are due to host lattice defects which may arise from S -2 ion vacancies, created during phosphor preparation.

The use of CaSO4:Tm powder for fast neutron dosimetry

An orientation independent dosemeter is reported here using a CaSO4:Tm phosphor powder recently developed in Japan (Yamashita, Nada, Onishi and Kitamura 1968). This phosphor combines very high sensitivity with a small intrinsic response to fast or thermal neutrons. Instead of using encapsulating walls of hydrogeneous substances to supply protons to react with the solid phosphor, the powdered phosphor has been mixed with a hydrogeneous powder (e.g. glucose crystals) in order to eliminate the angular dependence of response.