Relevance : The effectiveness of adjuvant radiation therapy used to consolidate the effect of chemotherapy in patients with malignant lymphomas remains a subject of debate and intensive study. The usefulness of chemoradiotherapy has been proven for certain lymphoma sites (mediastinum, central nervous system, bone, gonads), but its role in follicular lymphoma with primary involvement of the abdominal and/or pelvic lymph nodes has been insufficiently studied. Purpose : Determination of the effectiveness of chemoradiotherapy in primary patients with abdominal and pelvic nodal follicular lymphoma. Materials and methods : We studied the immediate effect of treatment, 10-year local progression-free survival (LPFS) and progression-free survival (PFS) of 77 primary patients with follicular lymphoma of the abdominal and pelvic lymph nodes treated in 1985–2024 at the Russian Scientific Center of Roentgenology and Radiology. Chemoresistant patients were not included in the study. The main group (43 patients) underwent chemoradiation therapy (CRT) with adjuvant irradiation of initially massive conglomerates of abdominal and/or pelvic lymph nodes, while the control group (34 patients) received chemotherapy alone. Identical chemotherapy regimens ± rituximab immunotherapy were used in both groups. The differences between the groups were statistically insignificant in terms of the main parameters that are potentially important for treatment outcomes. Results : Upon completion of radiation therapy in the main group, the rate of complete remissions statistically significantly increased from 23 % to 49 % (p = 0.014). The 10-year LPFS rate was statistically significantly higher in the CRT group as a whole (80 % vs 30 %, p = 0.00006), as well as in all analyzed subgroups, except for the subgroups of patients with a lesion size of 7 cm or less and patients with complete remission after chemotherapy. The 10-year PFS rate was statistically significantly higher in the CRT group as a whole (49.6 % vs 14.2 %, p = 0.0017), as well as in most compared subgroups and did not reach statistical significance in men, patients over 60 years of age, at local stages of the disease, in the high-risk group, patients treated without rituximab and patients with complete remission after chemotherapy. Conclusions : In primary patients with nodal follicular lymphoma of the abdominal and pelvic localization who are sensitive to chemotherapy, chemoradiotherapy significantly compensates for the low efficacy of chemoimmunotherapy in relation to massive tumor foci, which is expressed in a statistically significant increase in the proportion of complete remissions, a decrease in the initially high risk of subdiaphragmatic progression, and the achievement of a 10-year period free from disease progression in half of the patients.
Background. Primary brain tumor lesions include gliomas, which, according to epidemiological data, make up about 30% of all tumors of the central nervous system and are the most common. Overall and relapse-free survival rates depend on the degree of glioma malignancy and the histopathological nature of the detected lesion. For better treatment and prognosis, it is necessary to determine the exact location and histopathological nature of the tumor. Magnetic resonance imaging (MRI) remains the method of choice for structural brain assessment, but even with the use of contrast enhancement (CE), it does not always allow for reliable differentiation between tumor progression and post-therapeutic changes (radionecrosis, postoperative scars, cysts, inflammation) in patients after antitumor treatment. Radiopharmaceuticals, in particular 11C-L-methionine, provide an assessment of tumor amino acid metabolism and complement structural data, increasing diagnostic accuracy. MRI, positron emission tomography and computed tomography (PET-CT) with 11C-L-methionine in combination with morphological examination of the sample after stereotactic biopsy have shown high efficiency in the diagnosis of gliomas with varying degrees of malignancy.Objective: to study the possibilities of applying PET-CT with 11C-L-methionine in the diagnosis of continued growth and recurrence of glial tumors, as well as to conduct differential diagnostics with postoperative non-neoplastic changes.Material and methods. A retrospective, descriptive, analytical study was conducted in the Department of Radionuclide Therapy and Diagnostics of the Saint Petersburg Clinical Scientific and Practical Center for Specialized Types of Medical Care (Oncological) named after N.P. Napalkov. It included 67 patients (34 men and 33 women aged 17 to 75 years, mean age was 43.5±15.6 years) for whom PET-CT was carried out in the period from 2007 to 2015 after neurosurgical treatment with suspected continued growth of glial tumors. All patients underwent CE-MRI and CE-CT. Correlation coefficient (r) was used to estimate the level of dependence between PET-CT data.Results. In 55% of the cases, continued growth of high-grade gliomas (Grades IV and III) was detected. In these patients, the radiopharmaceutical accumulation index ranged from 1.3 to 5.1, with mean value 2.9±0.85. In patients with continued growth of benign astrocytomas, the degree of 11C-L-methionine accumulation varied with mean value 1.6±0.51. The sensitivity and specificity of PET-CT in detecting brain glioma progression were 92.3% and 73.3%, respectively. The combination of CE-MRI and PET-CT provided a sensitivity of 96.1% in diagnosing glioma tumor progression. The results show that MRI and PET-CT data are consistent in 45 of 48 cases (92.8%) of proven glioma progression. An accumulation index greater than 2 can predict continuous growth of malignant glioma with 95% accuracy, and the threshold for differentiating benign glioma from inflammatory lesions is 0.9.Conclusion. Although PET-CT has good sensitivity in differentiating postoperative lesions in patients with glioma, CE-MRI is necessary for localized and earlier diagnosis. The lack of visualization of avascular gliomas is one of the limitations of PET-CT, although CE-MRI does not exclude them.
The RSCAN PP20 prototype plane-parallel ionization chamber was evaluated for electron beam dosimetry and medium-energy kilovoltage x-ray beam measurements. This study investigated its response constancy, linearity, depth-ionization characteristics, voltage and polarity dependence, and signal stability in water using a 6 MeV electron beam and selected kilovoltage x-ray beam qualities. Additional time-resolved measurements were performed to assess dark-field charge transients, post-irradiation charge relaxation, in-beam current transients, and cable-related parasitic currents, with a PTW Advanced Markus chamber used as a reference-control detector. In the 6 MeV electron beam, the RSCAN PP20 prototype produced physically plausible depth-ionization curves but showed insufficient quantitative stability. The coefficient of variation reached 1.57%, and the relative range reached 5.10%. The apparent linearity deviation reached 16.8% when background compensation was performed only once per measurement series, but decreased to 0.64% when repeated before each measurement. A polarity correction factor of approximately 0.91 was obtained across the tested voltage range, indicating measurement-chain asymmetry rather than a conventional intrinsic polarity effect. Time-resolved recordings revealed dark-field charge transients, post-beam charge accumulation, and mechanically induced bipolar current spikes, consistent with parasitic currents and possible cable-related triboelectric effects. Fixed-depth measurements in kilovoltage x-ray beams showed better short-term stability, whereas depth-response scans demonstrated cable-dependent distortions. The main limitation of the current RSCAN PP20 prototype is not its basic plane-parallel geometry, which is close to established clinical designs, but instability of the prototype chamber-cable assembly within the tested measurement setup. The prototype is not yet suitable for routine clinical dosimetry in its current configuration and requires hardware improvements followed by comprehensive recharacterization.
