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Showing 12 results for Kaya
Y. Parlak, Dr. M. Demir, I. Cavdar, S. Ereees, G. Gumuser, B. Uysal, G. Capa Kaya, M. Koç, E. Sayit, Volume 14, Issue 2 (4-2016)
Abstract
Background: Radiation absorbed dose to the red bone marrow, a critical organ in the therapy of thyroid carcinoma, is generally kept below 2 Gy for non-myeloablative therapies. The aim of this study was to calculate bone marrow radiation dose by using MIRDOSE3 package program and to optimize the safe limit of activity to be administered to the thyroid cancer patients. Materials and Methods: In this study, 83 thyroid cancer patients were divided into 3 groups based on the amount of activity administered into the body. In the groups, 3700 MBq, 5550 MBq and 7400 MBq activities were used respectively. The curves of time-activity were drawn from blood samples counts and effective half-life and residence time were calculated. Correlations of bone marrow radiation dose and radioiodine effective half-life were determined as a function of administered activity via ANOVA test. Tg levels and tumour diameters were compared using Spearman’s correlation. Results: The effective half-lives of 131I for three groups of whole-body, receiving 3700 MBq, 5550 MBq and 7400 MBq were calculated as 20.57±5.4, 17.8±5.8 and 18.7±3.9 hours, respectively. The average bone marrow doses for 3 groups of patients were 0.32±0.08 Gy, 0.42±0.14 Gy and 0.60±0.24 Gy, respectively. Conclusion: It was concluded that, the bone marrow dose to the patients still remains within the recommended level even after administering an activity of 7400 MBq of 131I to the patients.
Dr. S. Barlaz Us, E. Kaya Pepele, Volume 15, Issue 1 (1-2017)
Abstract
Background: The purpose of this study was to investigate the various gantry angle and SSD dependencies of TLD and MOSFET dosimeters. Materials and Methods: LiF (Mg) TLD and MOSFET were used in this study. Dosimeter systems were calibrated and then irradiated at various gantry angle and SSD by applying 6 MV photon energy. Results: Based on the results, MOSFET changes were found to be in 2% range between ±50º gantry angles and the rate of dose change was found to be increasing as gantry angle was at the extremes of graph. This increase was especially obvious in tail end of the asymmetric axes. Change in the gantry angle dependency of TLD was -2% till ± 60º gantry angle and -5% between 60º to 90º. Dependency of SSD was ±1% for TLD and MOSFET. Conclusion: Results indicate that properties of dosimeters must be well known by users for accurate determination of the entire doses on the patient. These observations may lead to better treatment quality and prevention of probable dose errors.
Dr. F. Teke, H.m. Doğan, M.a. Kaya, M. Gümüş, Volume 15, Issue 3 (7-2017)
Abstract
Background: The purpose of this study was to evaluate the characteristics of TomoDirect (TD) plans compared to conventional TomoHelical (TH) plans in chest wall irradiation in patients with breast cancer. Materials and Methods: TD and TH plans for only chest wall were retrospectively created for 30 patients previously treated with TH technique in our clinic. The beam angles were arranged to cover PTV chest wall and to minimize doses to OARs, ipsilateral lung and contralateral breast in TD plan. The prescribed dose was 50 Gy in 25 fractions. Results: The mean treatment times were similar in TH and TD (310.8 and 309 s, respectively, p> 0.05). There was no difference between the values of CI and HI of both plans (p>0.05). The values of Dmean, V5 and V20 of the ipsilateral lung in TD plan was significantly lower than that in TH plan for all 30 patients (p<0.001, p<0.001 and p=0.001, respectively). V25 and V30 values of the heart were significantly lower in TH than those in TD plan in left-sided chest wall irradiation (p=0.006 and p<0.001, respectively). However, V5 values in TH was significantly higher than those in TD (p<0.001). In the right-sided, there was no difference between two plans for V25 and V30 values of heart (p>0.05). Conclusion: Both of TH and TD plans produce acceptable target dose coverage in chest wall RT. Considering the risk of low-dose radiation to the critical organs; TD mode improve dose distribution.
Dr. C. Koksal, N.d. Kesen, U. Akbas, U. Kalafat, K. Ozkaya, M. Okutan, E.m. Fayda, S. Kucucuk, H. Bilge, Volume 15, Issue 4 (10-2017)
Abstract
Background: The aim of this study was to compare the differences of the dosimetric parameters between three-dimensional conformal radiotherapy (3D-CRT) and simultaneous-integrated boost intensity-modulated radiotherapy (SIB-IMRT) techniques in the prone and supine positions for breast irradiation. Materials and Methods: Ten patients underwent a computed tomography simulation in both the prone and supine positions. For each set-up position, the treatment plans were created with 3D-CRT and SIB-IMRT. The dosimetric parameters were obtained from dose-volume histograms. Results: High-dose regions in the whole breast were decreased in IMRT with a simultaneous integrated boost technique. The lung doses were significantly reduced for all patients, and the heart doses were lower in left-sided breast cancer patients in the prone position. The heart doses except mean dose were not significantly lower with SIB-IMRT in the prone position. Conclusion: SIB-IMRT allowed a more conformal dose distribution regardless of position. The prone position is superior to the supine treatment regarding doses in the ipsilateral, contralateral lung, and heart. The contralateral breast doses were increased in the prone position. Prone IMRT can be chosen for simultaneous integrated boost treatment in women with pendulous breasts.
Ph.d., F.m. Gur, A. Ikinci Keles, H.s. Erol, C. Guven, E. Taskin, H. Kaya, H.e. Gur, E. Odaci, M.b. Halici, S. Timurkaan, Volume 19, Issue 1 (1-2021)
Abstract
Background: Mobile phones as an electronic device which are emitting radiofrequency-electromagnetic field (RF-EMF). In this study was intend to determine the contingent effects of cell phone induced RF-EMF on testicular tissue in adolescence. Materials and Methods: Rats in the RF-EMF group were exposed to 900 MHz RF-EMF, while sham and control rats were not. After the completion of the test steps, the testicular tissues which were rapidly removed from the body of sacrificed rats were examined by using histopathological and biochemical methods. Testicular tissues cut to 5 µm thickness undergo routine histological procedures. Thus, histopathological evaluation will be completed. Malondialdehyde (MDA), glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) levels in testicular tissues were measured by biochemical methods to determine whether oxidative stress occurred or not. Results: Histopathologic findings were not observed in any of the studied groups. There was also no difference between the groups in terms of localization of androgen and estrogen receptors. The incidence of apoptotic index and TUNEL-positive cells was similar in all three groups. In the RF-EMF group, although the levels of MDA and CAT were significantly higher, GSH levels were lower than the other groups. There was no essential difference between the groups in terms of SOD level. Conclusions: The obtained results of this study showed that exposed to 900 MHz RF-EMF in adolescents caused oxidative stress in the testes, but testicular damage which is caused to oxidative stress is remained too low to be detected by histopathological methods in this study.
Dr. G. Özkan, R. Sessiz Ak, N. Akkaya, H. Öztürk, Volume 19, Issue 3 (7-2021)
Abstract
Background: To measure the knowledge levels of dentists and dental students about radiation doses of dental imaging techniques. Materials and Methods: A structured questionnaire containing 13 questions was conducted to 251 participants (168 dentists and 83 dental students). The first 6 questions were related to their personal and professional information, and the remaining 7 questions were about the participants’ radiation education and knowledge about radiation doses. Chi-square test was used to determine the relationship between categorical variables, and P < 0.05 was considered statistically significant. Results: The data from 144 (57.4%) women and 107 (42.6%) men were obtained. Gender was not effective on knowledge about radiation doses during dental imaging (p = 0.222). The knowledge of dentists working at the university was statistically higher than those working in the state hospital or private dental offices (p < 0.001). Of the participants, 43.4% (n = 109) stated that the craniofacial mode of cone beam computerized tomography radiates less radiation than the actual dose range, while 32.7% (n = 82) said they had no idea. Conclusion: Most of the dentists and dental students underestimated the actual radiation doses of dental imaging techniques. The dental curriculum should be revised to emphasize radiation protection during imaging. In addition, compulsory vocational postgraduate courses should be organized.
M.d., S.b. Zincircioglu, M.h. Dogan, M.a. Kaya, F. Teke, Volume 19, Issue 4 (10-2021)
Abstract
Background: The importance of dose in prostate radiotherapy is well known, and the dosimetric effects of radiotherapy in node-positive or node-negative patients with prostate cancer have become an important issue. Materials and Methods: Helical tomotherapy (TH) plans of 19 pelvic node-positive [THpn(+) plan] or node-negative [THpn(-) plan] patients with prostate cancer were retrospectively created in our clinic. In these plans, the beam angle was set to cover the planning target volume (PTV) of prostate cancer and minimize the dose to the organs at risk, including the bladder, rectum, femoral head, and bowel. Results: There were no differences in the conformity index, Dmax, Dmean, and homogeneity index of PTV between the THpn (+) and THpn (-) plans (p>0.05). However, V95 in the THpn (+) plan was lower than that in the THpn (-) plan (p=0.017). Moreover, Dmax, V75, V70, V65, V60, V50, V40, V30, and V20 for the rectum were not significantly different between the two plans (p>0.05), whereas Dmean was significantly different (p=0.025). Dmax, V70, V65, and V60 for the bladder were not significantly different between the two plans (p>0.05), whereas V55, V50, V40, and V30 were significantly different (p<0.05). Finally, Dmax and V50 for the femoral head and bowel were significantly different between the two plans (p<0.05). Conclusion: The THpn (+)] and [THpn(-) plans achieved acceptable target dose coverage in prostate radiotherapy.
Ph.d., T. Takayama, T. Sugihara, T. Kameda, M. Yamazaki, M. Komatsubara, J. Kamei, A. Fujisaki, S. Ando, T. Fujimura, Volume 20, Issue 1 (1-2022)
Abstract
Background: We investigated therapeutic outcomes of Radium-223 (Ra-223) treatment in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases. Materials and Methods: Outcomes were retrospectively examined in 20 patients starting Ra-223 treatment at a single university hospital from January 2017 to January 2020. Results: Median patient age was 70 years. Median values included prostate specific antigen (PSA) 10.73 ng/ml, PSA doubling time (PSADT) 3.7 months, alkaline phosphatase (ALP) 315 IU/L, lactate dehydrogenase (LDH) 186 IU/L, neutrophil-to-lymphocyte ratio (NLR) 2.22, and Gleason score 9. Extent of disease (EOD) was 3 or more in 55%, and Eastern Cooperative Oncology Group performance status was 0 in 80%. 16 patients (80%) completed Ra-223 treatment. Ra-223 was administered in 11 (55%) with ≤ 3 lines of treatment and 9 (45%) with ≥ 4. Concomitant drug was enzalutamide and abiraterone in 6 and 7 patients, respectively. Bone modifier agents (BMA) were used in 11 patients. Symptomatic skeletal events (SSE) occurred in 5 patients and were associated with abiraterone combination. BMA during Ra-223 treatment did not affect SSE. Median overall survival from initiation of Ra-223 treatment was 32.7 months. Prognosis was significantly better with PSADT ≤ 3 months, EOD ≤ 2, no SSE, no opioid use, and completion of Ra-223 treatment. PSA, LDH, NLR, PSADT, and Ra-223 treatment line after mCRPC were associated with Ra-223 completion. Anemia of Grade 3 occurred in 1 patient. Conclusion: Ra-223 treatment is safe, with good prognosis if completed. Combination treatment with abiraterone during Ra-223 treatment may cause SSE.
Ph.d., T. Berber, I. Harmankaya, F. Aksaray, Y. Büyükpolat, F. Adatepe, B.d. Yilmaz, S.t. Dinçer, G. Coşgun, Ç. Numanoglu, M.n. Güven, M.e. Gül, C. Yildirim, A.a. Erken, Volume 20, Issue 3 (7-2022)
Abstract
Background: To elucidate the efficacy and toxicity of brain re-radiotherapy for recurrent large inoperable gliomas using radiosurgery. Materials and Methods: Between 2014 and 2018, extreme hypofractionated radiosurgery was performed using Accuray’s Cyberknife® system on 14 lesions (12 patients) grade 4 recurrence lesions of 6 patients with anaplastic astrocytoma and 6 patients with glioblastoma who had previously undergone surgery and cranial radiotherapy and had a local-regional recurrence. Six patients (8 lesions) were given a biologic effective dose (BED10) of 48 Gy and lower, and six patients were given a BED10 of 59.5 Gy and higher. The Response Assessment in Neuro-Oncology Criteria (RANO) were used for tumor response, and the Common Terminology for Adverse Events (CTCAE) was used for adverse effect assessment. The primary endpoint was determined as overall survival, and first treatment and salvage treatment time. Results: The median age of the patients was 43 years, and the median Karnofsky Performance Status (KPS) was 70. The median time from the first radiotherapy to death was 34 months. The median time from the previous radiotherapy was 29.5 months (R:17-40). The median survival was 10 months for those with recurrence before 29.5 months and 11 months for those with recurrence after 29.5 months. The median total tumor volume was 29.224 mL (~30 mL). One grade 4 toxicity was observed. Conclusion: Radiosurgery can be used effectively as salvage therapy in ultra-large inoperable gliomas.
Ph.d., M. Biçer, H. Çetinkaya, Volume 21, Issue 3 (7-2023)
Abstract
Background: Milk is a fundamental part of the human daily diet, so radioactivity concentrations in milk must have been controlled regularly. In this study, radiation activities were measured in 12 ultra-high temperature (UHT) milk samples collected in Kütahya, Turkey, in August 2021. Materials and Methods: Radium (Ra-226), thorium (Th-232) and potassium (K-40) values were determined by using the Canberra 3x3 NaI(Tl) gamma spectroscopy method in 8 samples, and Radon (Rn-222) activity measurements have been conducted in 12 samples using the E-perm method. Results: Radium (Ra-226), thorium (Th-232) and potassium (K-40) levels are measured as < MDA (2.28 Bq/kg), < MDA (2.53 Bq/kg), 40.43 ± 2.25 to 53.31 ± 2.30 Bq/kg, respectively. Radon (Rn-222) concentrations were determined by the E-perm system between 0.46 ± 0.02 and 2.01 ± 0.05 Bq/l with an average of 1.11 ± 0.03 Bq/l. Conclusions: Annual ingested radiation doses were calculated using radioactivity levels for different age groups as a result of milk consumption. Ingestion dose levels are below the worldwide average values given in the UNSCEAR report. It has been observed that the results are below the safety limits.
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