The results of measurements of the local irradiation dose to the most highly irradiated sections of the body of a therapy provider -the skin on the fingers and palm and regions of the chest -are presented. The measurements were performed by the method of thermoluminescence dosimetry using highly sensitive TLD-500K detectors. It was established that even for the highest total activity of these sources (1221 MBq) and the longest period of work without the use of x-ray protective gloves the maximum dose (minus the natural background and take the account to the energy dependence of the sensitivity of the detector) to the provider is 0.18 ± 0.01 mGy (the large finger on the right hand was exposed to the highest irradiation level) and 0.01 ± 0.0004 mGy (the outer side of the palm of the left-hand was exposed to the lowest irradiation level), which does not present a radiation hazard even when working repeatedly with the sources.Intratissue radiation therapy of prostate cancer (brachytherapy) using permanent encapsulated microsources containing 125 I is being increasingly used in different countries throughout the world, including in our country [1, 2], since it is noninvasive and an effective method for treating this disease. According to ICRP Publication No. 98 [3], the effective yearly irradiation dose to the people surrounding the patient with implanted 125 I sources after release from the clinic is low and does not exceed 1 mSv. At the same time, data on the irradiation dose to the providers of this form of therapy are not available in the accessible literature. The present paper presents the results of measurements of the local irradiation dose to providers, specifically, to the skin on the fingers and palms of the operator as well as the surface of the chest region. It should be noted that the fingers and wrists are the most highly irradiated body parts in brachytherapy using 125 I sources.Materials and Methods of Investigation. 125 I decays by electron capture with half-life 60.2 days ( Table 1). The encapsulated microsources of 125 I which are used at the Medical Radiological Science Center (MRSC) (InterStrand 125 , Mod. 125I S, Belgium) consist of airtight 4.5 mm long and 0.8 mm in diameter of cylindrical titanium capsules, sealed at both ends, with a 0.05 mm thick titanium shell, which contain the material with the radionuclide substance on a 17 mm in diameter gold wire (along the axis of the cylinder). The wire is necessary to show the position of the capsule using x-rays. The capsules are secured on a polymer resorbing filament. The activity of the microsources ordinarily used for implantation ranges from 7.4 to 74 MBq per capsule (depending on the dosimetric plan of the operation).TLD-500K thermoluminescence detectors, consisting of anion-deficient α-Al 2 O 3 :C single crystals, which have a high sensitivity (10 −6 Gy) at a low dose equivalent of the intrinsic background (less than 3·10 −7 Gy), good accuracy in measuring the dose for photon energy ranging from 10 keV to 3 MeV, low fading (less than 3% pe...

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