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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: Radiotherapy,Accuracy,Wedge,Treatment Planning,Dose
- چکیده:
- چکیده انگلیسی: Introduction
Wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. Since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (TPS) is important. The objective of the present study was to quantify the dose calculation accuracy of TiGRT TPS for physical wedged fields in radiotherapy.
Materials and Methods
A Semiflex™ ionization chamber was used for dose measurements in a water phantom; TiGRT TPS was also applied for dose calculations. The central axis (i.e., high dose-small dose gradient), build-up (i.e., high dose-large dose gradient), off-axis (i.e., high dose-small dose gradient), and out-of-field (i.e., low dose-small dose gradient) regions were evaluated in this study. Finally, the confidence limit values were obtained to quantify the dose calculation accuracy of TPS in these regions.
Results
The confidence limit values for the central axis, build-up, off-axis, and out-of-field regions were 1.01, 8.62, 1.79, and 55.24, respectively. Furthermore, the results showed that TiGRT TPS underestimated the dose of build-up and out-of-field regions for most points.
Conclusion
According to the results of the present study, it can be concluded that the dose calculation accuracy of TiGRT TPS for physical wedged fields in the central axis, build-up, and off-axis regions is adequate, while it is insufficient for out-of-field regions.- انتشار مقاله: 23-01-1395
- نویسندگان: Bagher Farhood,Mohammad Taghi Bahreyni Toossi,Shokouhozaman Soleymanifard
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: Antioxidant,Allium sativum,MCF7 Cells, Radiation-Induced Bystander Effect,Raw Garlic
- چکیده:
- چکیده انگلیسی: Introduction
Radiation-induced bystander effect (RIBE) is a phenomenon in which radiation signals are transmitted from irradiated cells to non-irradiated ones, inducing radiation effects in these cells. RIBE plays an effective role in radiation response at environmentally relevant low doses and in radiotherapy, given its impact on adjacent normal tissues or those far from the irradiated tumor. Reactive oxygen species contribute to RIBE induction. Therefore, the present study was conducted to investigate the possible inhibitory effects of garlic, as an antioxidant-containing plant, on RIBE.
Materials and Methods
MCF7 cells, treated with raw garlic extracts, were irradiated by 60Co gamma rays, and their culture medium was transferred to non-irradiated autologous bystander cells. Percentage cell viability and micronucleus formation in both irradiated and bystander cells were examined and compared with corresponding cell groups, not treated with garlic.
Results
Treatment with garlic extract reduced the number of micronucleus-containing cells in both irradiated and bystander cells. However, it only increased the percentage cell viability in bystander cells, not the irradiated ones.
Conclusion
RIBE was effectively suppressed by raw garlic extracts. Inhibitory effects of raw garlic may be of particular importance for exposure to environmentally relevant low doses, where RIBE dominates direct radiation effects. They are also partially important for addressing the limited therapeutic gain of radiotherapy, as they may only increase the percentage cell viability of bystander cells, not the directly irradiated tumor cells. However, more comprehensive in-vivo research regarding garlic treatment duration is required to support the obtained results.- انتشار مقاله: 14-02-1393
- نویسندگان: Shokouhozaman Soleymanifard,Mohammad Taghi Bahreyni Toossi,Shokoufeh Mohebbi,Ameneh Sazgarnia,Seyed Ahmad Mohajeri
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: CNS,TPS,Thermoluminescent Dosimetry,Craniospinal irradiation
- چکیده:
- چکیده انگلیسی: Introduction: Craniospinal radiotherapy is a therapeutic technique for central nervous system (CNS) tumors, which requires meticulous attention to technique and dosimetry.Treatment planning system (TPS) is one of the main equipment in radiotherapy; therefore, the evaluation of its accuracy is essential for dose calculation. The present study evaluates the validity of Isogray TPS in craniospinal irradiation techniques.
Material and Methods: The computed tomography (CT) images of the brain and spine of the Rando phantom were acquired. Two techniques were designed. In technique 1, the whole CNS was irradiated with 6 MV photon beam. In technique 2, the brain and spine were irradiated with 6 MV photon and 18 MeV electron beam, respectively. The tumor and organs at risk doses were measured by thermoluminescent dosimeter (TLD). In addition, photon and electron dose measurements inside and outside the treatment field were accomplished using TLD, and then compared to the corresponding values calculated by TPS.
Results: According to the results, in both electron and photon beams, the differences between the doses calculated by TLD and TPS for the points inside the treatment field were less than 4% for 90% of the measurement points. However, for the points outside the treatment field borders, the differences ranged within 10-40%. These differences were indicative of the sufficient dosimetric accuracy of Isogray TPS.
Conclusion: The comparison of dosimetry results with those of TPS results revealed the accuracy of Isogray TPS. In both techniques, the maximum difference between the TLD- and TPS-measured doses was observed in the mandible.- انتشار مقاله: 28-09-1396
- نویسندگان: Mohammad Taghi Bahreyni Toossi,Sara Momeni,Shokouhozaman Soleymanifard,Hamid Gholamhosseinian
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Pacific Journal of Cancer Prevention
- نوع مقاله: Journal Article
- کلمات کلیدی: Gamma Irradiation,Vinblastine,micronucleus assay,L929 cell
- چکیده:
- چکیده انگلیسی: Objectives: Vast number of studies show the relationship between aneuploidy and cancer. Ionizing radiation in
addition to induce all kinds of damages to the cells and structure of chromosomes, is also able to induce aneuploidy
through direct damages to chromosome division apparatus. Also irradiation of the cells induces mutations in several
genes which might be involved in cell division fidelity and play a role in reversing the effect of aneugens. Therefore,
irradiation of cells and tissues might produce sensitivity to agents with aneugenic capability in irradiated cells. Methods:
To investigate the persistent genomic effect of ionizing irradiation on chromosomal instability, L929 cells were gamma
irradiated with the dose of 2 Gy. Cells were left to recover from the harmful effect of irradiation. They were treated with
low dose of vinblastine (0.5 ng.ml-1) 72h post-gamma irradiation. Finally, the induced chromosomal abnormalities
were scored using micronucleus assay in cytokinesis-blocked binucleated cells (MnBi). Results: Irradiation-recovered
L929 cells treated with vinblastine showed a statistically higher frequency of MnBi compared to non-irradiated and
vinblastine treated cells. Conclusion: The results indicate that gamma irradiation, in addition to direct induction of
chromosomal damages, is also able to create persisting genomic sensitivity in the cells to chromosomal instability,
which is detectable when exposed to the second stimulus.- انتشار مقاله: 28-11-1396
- نویسندگان: Zahra Mohammadi,Farhang Haddad,Maryam M Matin,Shokouhozaman Soleymanifard
- مشاهده