The paper describes clinical cases of conformal re-irradiation of recurrent squamous cell carcinoma of the head and neck. The use of current technological advances in radiotherapy permits re-irradiation of tumors in effective single (hypofractionation) and cumulative focal doses (CFD) and a reduction of radiation exposure to adjacent normal structures. CFD reconstruction of conventional pre-irradiation enables one to estimate the risks of possible complications due to re-irradiation.Keywords: conformal radiotherapy, re-irradiation, hypofractionation, squamous cell carcinoma of the head and neck.
The study was aimed to the biological effectiveness of the proton scanning beam of the first Russian medical facility. The clonogenic assay of B-16 tumor cells was used as a test system. Cell irradiation was carried out in a suspension condition in a water phantom. Single and three-field exposures were studied. The dose interval was 2-8 Gy. The energy range from 47.5 to 92.0 MeV was used for the Bragg peak formation. The relative biological effectiveness of protons comparing to gamma-rays was 1.2 for single-field and 1.5 for three-field irradiation. The results obtained agree with literature data related to the used cell culture (B-16) and linear energy transfer range (3÷8 keV/µm).
Introduction. One of the effective and minimally invasive methods prostate cancer treatment is interstitial radiation therapy, the essence of which is the implantation of radioactive microsources into the tumor tissue. Brachytherapy of prostate cancer is performed in more than 20 clinics in the Russian Federation using mainly foreign microsources, but their high cost does not allow increasing the number of operations and opening new brachytherapy departments in the Russian Federation. Based on the model of foreign microsources such as seed No. 6711 (Nicomed Amersham), a technology for the manufacture of microsources with iodine-125 (IPPE SEED) has been developed at the State Research Center of the Russian Federation - IPPE, as well as a pilot production facility with a capacity of up to 50 thousand items per year. Materials and methods. In order to assess the safety of microsources for medical personnel during brachytherapy, local dosimetric control was carried out. As part of a clinical study in 2015, 36 patients with stage T1 – T2 prostate cancer underwent low-power brachytherapy using domestic microsources. Results. The obtained values of absorbed doses do not differ within the limits of measurement errors from the values of doses determined during the operation with foreign microsources under similar conditions. It follows from the data obtained that even the maximum values of the measured local absorbed doses do not pose a radiation hazard when using IPPE SEED microsources for brachytherapy. Among the treated patients, adverse reactions were in the expected manifestations of grade 1 dysuria according to the RTOG / EORTC classification. No gastrointestinal toxicity has been reported. Patient monitoring was continued in order to obtain long-term results of treatment. PSA disease-free survival at 5-year follow-up was 94.4%. Discussion. Clinical trials of Russian medical devices have demonstrated their safety for patients and medical personnel, which was proved by conducting dosimetry control during the procedure itself, as well as during examination of patients after brachytherapy. The effectiveness of Russian microsources I-125 during low-power brachytherapy is demonstrated by a decrease in PSA level from baseline by 87% at a follow-up period of 6 months. The disease-free survival rate for 5 years was 94.4%. The absence of significant radiation reactions both in the early and in the late postoperative period is important. The low cost of microsources produced by JSC «SSC RF – IPPE» relative to foreign analogs makes it possible to increase the number of operations performed annually, and also gives prospects for opening new divisions performing interstitial radiation therapy operations. Conclusions. Russian microsources «IPPE SEED» have successfully passed clinical trials, during which their effectiveness and safety were proved. The study also demonstrated high rates of relapse-free survival and a low level of adverse reactions in treated patients.
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