[Metrological support of clinical dosimetry]. / Metrologicheskoe obespechenie klinicheskoi dozimetrii.

The main requirement for the dosimetric support of radiation therapy for cancer disease is the necessity of keeping the high accuracy of dosimetric planning of radiation therapy. This dosimetric planning involves a number of components including the measurement of the supporting dose, the establishment of a correct orientation of a primary beam, the receipt of accurate data on the distribution of organs and tissues in the radiation area. In fact, in all the above components there are errors in the estimation of the basic values, which totally determine the total error in the dosimetric planning of radiation therapy. The paper analyzes the constituents of the errors and show their requirements to be met at the present stage of dosimetric works.

Materials for thermoluminescent dose detectors and photon radiation energy detectors intended for intercomparison procedures of radiation therapy units.

Composite thermoluminescent (TL) materials characterized by different TL sensitivity to energy of photon radiation, namely, double-component mixtures of finely dispersed ingredients: thermoluminescent phosphor (LiF or CaSO4:Dy) and nonluminescent material (salts with various Zeff values) have been described. The TL sensitivity of such TL composites was demonstrated to depend upon Zeff values inherent to separate components and upon their concentration ratio in the mixture. Within the range of x-ray energy values from 10 to 120 keV, the LiF-based materials containing Li2CO3 as nonluminescent material were dosimetrically equivalent to soft tissues. The availability of powder-like TLD materials containing 65% LiF + 35% Li2CO3 can definitely serve the basis for extending the application area for the well-known procedure adopted by IAEA/WHO for comparative testing of x-ray therapy units with HVL < 0.5 mm Cu and for starting the intercomparison of units intended for superficial x-ray therapy. The use of the dose detectors based on TLD of 35% LiF + 65% Li2CO3 composition in orthovoltage x-ray therapy units excludes the necessity for introducing corrections for the dependence of detector's readings on energy levels. LiF- and CaSO4:Dy-based TL materials containing PbSO4 as a nonluminescent material are, by a factor of 10, more sensitive to energy variations than other known thermoluminescent phosphors. With the application of TLD based on above materials into two-detector systems intended for determining Eeff values of x-ray radiation, the ambiguity of readings in low-energy region has been eliminated, whereas the range of measurement appeared to be significantly expanded.

A new method of trabecular bone tissue dosimetry.

A new method of trabecular bone tissue dosimetry has been developed using solid-state materials. For measurement of photon radiation doses, trabecular bone was modeled by a mixture of two substances, a thermoluminescent phosphor and a nonluminophor, each of which is dosimetrically equivalent to either trabecular or red bone marrow, and each of which has a particle size range appropriate for one of the two tissue types that it represents. The ratio of components corresponds to the ratio of red bone marrow and trabecular bone as determined in actual bone samples. Characteristics of the dosimetric models for a few types of trabecular bone are given. Equivalence of the dosimetric characteristics of the various mixtures of thermoluminescent and nonluminophor materials to the corresponding characteristics of various types of trabecular bone have been derived and verified by experiment.

[The measurement of the characteristics of x-ray radiation generated by video display terminals by using thermoluminescent detectors]. / Izmerenie kharakteristik rentgenovskogo izlucheniia, generiruemogo videodispleinymi terminalami, s pomoshch'iu termoliuminestsentnykh detektorov.

Exposure doses of X-rays generated by video displays were measured by means of highly sensitive TLD-500K type detector based on thermoluminophore Al2O3 and DTG-4 type detector based on thermoluminophore LiF. Individual human doses and doses accumulated on the display's surface can be measured. Trials showed efficiency of the method to evaluate the efficacy of protective screens for reducing the irradiation exposure.

[Metrological and operating characteristics of thermoluminescent and photographic film dosimeters for the centralized individual dosimetric monitoring of medical personnel]. / Metrologicheskie i ékspluatatsionnye kharakteristiki termoliuminestsentnykh i fotoplenochnykh dozimetrov dlia tsentralizovannogo individual'nogo dozimetricheskogo kontrolia meditsinskogo personala.

Characteristics of a TLD thermoluminescent kit with LiF detectors of TLD and DTG-4 types (diameters 3.5 and 5 mm) and TLD-400 were compared with those of a kit of IFKU-1 individual photographic film badges. Individual thermoluminescent dosimeters record a total dose of occupational and background irradiation, and film badges--a dose of occupational irradiation only. It should be taken into account in radiation-hygienic interpretation of individual dosimetric control readings.