В фотон-захватной терапии (ФЗТ) величина поглощенной дозы определяется не только параметрами облучения, но и концентрацией дозоповышающего агента (ДПА) в облучаемом объекте. В данной работе было проведено расчетно- экспериментальное исследование распределения поглощенной дозы на опухолевой модели мышиной меланомы B16F10, после однократной интратуморальной инъекции висмута в качестве ДПА в форме водного раствора комплекса Bi-ДТПА. Оценку поглощенной дозы проводили для однофракционного рентгеновского облучения длительностью 28,5 мин. Количественное определение ДПА in vivo осуществляли при помощи микро-КТ, используя значения рентгеноплотности опухолевых тканей на полученных КТ-томограммах. В результате исследования установлено, что за счет присутствия ДПА в 6% объема опухоли поглощенная доза увеличивалась более чем в 2 раза и в 29% объема опухоли наблюдалось увеличение поглощенной дозы отличное от 1. Время задержки роста опухоли, рассчитанное для полученного дозо-объемного распределения с учетом только непосредственного радиационного поражения опухолевых клеток, составило 0,76 суток, тогда как в ранее проведенных экспериментальных исследованиях данная величина равнялась 10 суткам. Полученное несоответствие может указывать на то, что торможение роста опухоли при ФЗТ с интратуморальным введением ДПА достигается за счет не только непосредственного радиационного поражения опухоли, но и иных противоопухолевых механизмов.

Background. For preclinical studies of radiopharmaceuticals there is a high need for development new methods of in vivo metastasis diagnosis in mice after tumor cells transplantation. The study was carried out to assess feasibility of lung metastasis diagnosis with magnetic resonance imaging (MRI) visualization in mice C57Bl6.The aim of this study was to assess feasibility of MRI for verification of distant metastases of the solid B16-F10 melanoma with validation by anatomic dissection.Methods. Metastatic lesions were caused by injection of B16-F10 murine melanoma cells into cavum medullare of the tibia. Imaging studies were performed on the 21th day after transplantation using 7T magnetic resonance tomograph, coronal and axial images were acquired. Validation of metastasis was made by anatomic dissection and histological examination.Results. MRI method enables visualization of lung nodules with diameter at least 0.8 mm, because smaller nodules cannot be distinguished from heartbeat artifacts. Histological examination revealed that macroscopic anatomic dissection can precisely detect subpleural lung nodules.Conclusion. This study demonstrated feasibility of in vivo lung metastasis verification with MRI method in mice: metastases comparable in diameter to the size of large bronchi can be detected by MRI as well as by ex vivo dissection. For centrally located lung metastasis MRI method is preferable because macroscopic dissection enables to visualize only nodules which are located subpleurally.

The object of the study was to analyze radionuclide detection techniques for in vivo animal imaging. Material and Methods. A total of 49 publications available from Scopus, Web of Science, Google Scholar eLIBRARY and Pubmed and published between 2013 and 2019 were reviewed. Results. The nuclear medicine techniques, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) are the most suitable imaging modalities for in vivo animal imaging. Besides traditional radiopharmaceuticals, such as [18F]-FDG and [99mTc]-MDP, the new radiolabeled tracers, such as [99mTc]-3PRGD2, [ 99mTc]-HisoDGR targeted to integrin, [18F]- tetrafluoroborate, labeled antibodies and others have been used for the noninvasive detection of tumors and for monitoring their response to treatment in mice and rats. 111In and 89Zr –labeled monoclonal antibodies are used to evaluate the expression level of many receptors such as EGFR, HER-2 and others in different tumors. PET imaging has demonstrated a good efficacy in tumor hypoxia imaging with [64Cu]-ATSM, [18F]-FMISO. PET and SPECT can also be used for early evaluation of anticancer therapy response. Nuclear imaging techniques may assist in the vivo assessment of DNA damage (doubleand single-strand brakes) as well as apoptosis intensity in tumor and normal tissues. [99mTc]- duramycin is the most commonly used tracer for imaging of apoptosis. Changes in tumor cell proliferation in response to anticancer therapy can be assessed by PET imaging with [18F]-FLT. Conclusion. Nuclear medicine offers a unique means to study cancer biology in vivo and to optimize cancer therapy. 

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