[Home ] [Archive]    
:: Main :: About :: Current Issue :: Archive :: Search :: Submit :: Contact ::
Main Menu
Home::
IJRR Information::
For Authors::
For Reviewers::
Subscription::
News & Events::
Web Mail::
::
Search in website

Advanced Search
..
Receive site information
Enter your Email in the following box to receive the site news and information.
..
ISSN
Hard Copy 2322-3243
Online 2345-4229
..
Online Submission
Now you can send your articles to IJRR office using the article submission system.
..

AWT IMAGE

AWT IMAGE

:: Search published articles ::
Showing 8 results for Fractionation

S. Nikzad, Dr. B. Hashemi, H. Mozdarani, M.h. Zuhair,
Volume 13, Issue 1 (1-2015)
Abstract

Background: Increasing the complexity in modern radiotherapy techniques have increased the delivery time lowering consequently the treatment efficacy. Through simulating the delivery time delay encountered in such techniques, its’ effect on two cancer cell lines and the compensating doses given to prevent such effect was investigated. Materials and Methods: F10B16 and 4T1 cancer cell lines were exposed to simulated clinical fractionated radiotherapy procedures commonly used in complex techniques. The survival rate of the cells exposed to 2, 4, and 6 Gy of ionizing radiation with two equal subfractions given at various time intervals between the fractions (0.25-4 hours) were determined using the MTT assay. Then, relevant compensating doses were calculated and their efficacy in counterbalancing the time delay was assessed. Results: The cells’ survival was increased with prolonged treatment times in the fractionated groups being more significant at the lower time intervals (up to 2 hours) and for the higher radiosensitive cells (4T1). Giving the compensated doses decreased the survival of the cells. Conclusion: Delivering appropriate compensating doses to the prolonged fractionated groups can counterbalance the effect of time delays encountered in complex radiotherapy techniques.


H. Zarei, Professor H. Mozdarani, A. Mahmoudzadeh, M. Salimi, H. Eyni, M. Bakhshandeh,
Volume 16, Issue 1 (1-2018)
Abstract

Background: Due to abscopal effect, cell damage may occur outside of the radiation field and the quantification of this effect is one of the most challenging debates in radiation therapy. The aim of this study was to estimate the abscopal effect induced in non-irradiated tumors quantitatively by means of biological effective dose (BED). Materials and Methods: Breast tumors using 4T1 and MC4-L2 cells, were induced into the flank region of Balb/c mice. When palpable, the tumor on one side of the body was irradiated with dose of 28Gy in 14 fractions and 2 Gy per fraction, 5 fractions per week. The tumor on the other side of the body was shielded with a lead plate. BED was estimated based on tumor volume. H&E staining and TUNEL assay were performed to assess histological changes and apoptosis in irradiated and non-irradiated tumors. Results: The effect of radiation on non-irradiated tumors was more than that on irradiated ones. The BED was 4.49 and 6.74 in 4T1 and MC4-L2 tumors, respectively. The ratio of the tumor volume in the last fraction to that in the first fraction for irradiated 4T1 tumors was 2.32 and in non-irradiated was 1.50. This ratio in irradiated and non- irradiated MC4-L2 tumors was 2.64 and 1.98, respectively. The number of apoptotic cells was higher in non-irradiated tissues. Conclusion: Results indicate that the occurrence of abscopal effect is highly depends on the type of tumor. By means of the abscopal effect, more radiation dose can be delivered to the tumor and metastatic sites.
 

M.d., H.j. Kim, J.s. Lee, W.c. Kim,
Volume 17, Issue 2 (4-2019)
Abstract

Background: Based on the radiation biology model of prostate cancer, hypofractionated radiotherapy can improve the treatment outcomes without increasing toxicity. Although hypofractionated radiotherapy is implemented over a short period of time, it is more convenient and cheaper compared with conventional fractionated treatment. The aim of this study was to investigate the early toxicity of moderate hypofractionated schedules with volumetric modulate arc radiotherapy (VMAT) for localized prostate. Materials and Methods: Between 2014-2017, 41 patients were treated using the volumetric modulated arc radiotherapy (VMAT) technique with image guided radiotherapy. The target volume for low risk patient (2.4%) was the prostate alone, and that for intermediate (43.9%) and high risk patients (53.7%) was prostate and two thirds of the seminal vesicles. A prescription dose of 70 Gy in 2.5 Gy daily for 28 treatment was used. Radiotherapy-related toxicity was scored according to the Common Terminology Criteria for Adverse Events 4.0 criteria. Results: Early genitourinary (GU) toxicity was recorded for grades 0, 1, 2 and 3 in 7 (17.1%), 25 (61.0%), 9 (21.9%) and 0 patients, respectively. Most common GU toxicities were urinary frequency and urgency. Early gastrointestinal (GI) toxicity was observed for grade 0, 1 and 2 in 35 (85.4%), 6 (14.6%) and 0 patients, respectively. Most common GI toxicity was rectal discomfort but interventional therapy was not indicated. Conclusion: The moderate hypofractionated VMAT radiation therapy with precise dose delivery technique appeared safe with low early toxicity. Longer follow up is needed to assess late toxicity and tumor control probability.

Phd., H.j. Kim, J.s. Lee, W.c. Kim,
Volume 18, Issue 3 (7-2020)
Abstract

Background: Stereotactic body radiotherapy (SBRT) is an emerging treatment option which allows for extreme hypofractionation using modern technologies, because the low α/β-ratio favors the use of high dose per fraction in prostate cancer. There is a need for more data about SBRT. We provide a long-term update of SBRT clinical outcome using CyberKnife for the treatment of localized prostate cancer. Materials and Methods: This study was based on a retrospective analysis of 43 patients treated with SBRT using CyberKnife for localized prostate cancer (23.3% in low risk, 67.4% in intermediate risk and 9.3% in high risk). The target volume included the prostate with or without the seminal vesicles depending on the risk stratification and uncertainty margins that are kept at 3-5 mm. Total dose of 36.25 Gy in 5 fractions of 7.25 Gy were administered. Results: 43 patients with a median 73.6 months (range, 14 to 119 months) follow-up were analyzed. There was three biochemical failure (BCF). Eight-year BCF free survival and overall survival were 92.0% and 73.1%, respectively. Median PSA decline rates were -0.301, -0.191 and -0.115 ng/mL/month, respectively, for durations of 1, 2 and 3 years after radiotherapy and has remained plateau. Median PSA nadir was 0.27 ng/mL at median 38 months and PSA bounce (median 0.33 ng/mL) occurred in 32.6% (n = 14) of patients at median 19 months after SBRT. There was no grade 3 acute and late toxicity. Conclusion: Our long-term experience with SBRT using CyberKnife for localized prostate cancer demonstrates favorable efficacy and toxicity.

M.d., H.j. Kim, J.s. Lee, W.c. Kim,
Volume 19, Issue 2 (4-2021)
Abstract

Background: Technical advances have allowed the delivery of a higher dose to the tumor volumes, while reducing the dose to nearby organs at risk. Laboratory and clinical evidence suggest that hypofractionation might raise the therapeutic effect. We report our outcomes of moderately hypofractionated schedules with volumetric modulated arc radiotherapy (VMAT) on biochemical failure (BCF) free survival and toxicities in patients with localized prostate cancer. Materials and Methods: Between 2013 and 2017, 58 patients were treated using the VMAT technique with daily image guided radiotherapy (IGRT). 3 (5.2%), 32 (55.2%), and 23 (39.7%) of patients had low, intermediate, or high risk disease, respectively. A prescription dose of 70 Gy in 2.5 Gy daily for 28 fractions was used. BCF-free survival was evaluated using 2005 Phoenix criteria and estimated using the Kaplan–Meier method. Radiotherapy-related toxicity was scored according to the Common Terminology Criteria for Adverse Events 4.0 criteria. Results: The median follow-up was 37.3 months (range 18.8-82.1). Overall 4 year BCF-free survival were 94.0%. For low-intermediate and high risk patients, the 4 year BCF-free survival were 100% and 83.3%, respectively (p=0.027). Pretreatment prostate-specific antigen (p=0.016) and Gleason score (p=0.007) were significant predictors of BCF-fee survival. The incidence of late grade 2 gastrointestinal and genitourinary toxicity was 8.6% and 13.8%, respectively. No grade 3 or greater toxicities were observed. Conclusions: Outcoms after moderately hypofractionated VMAT-IGRT were encouraging. Moderate hypofractionation was effective and safe for the treatment of localized prostate cancer.

H.q. Gao, Y.z. Wan, X.m. Bu, X.y. Fan, X.x. Xie, X.n. Ji, Ph.d., W. Song,
Volume 19, Issue 4 (10-2021)
Abstract

Hypoxia, a common phenomenon in solid tumors can promote dysfunctional vascular growth and epithelial-to-mesenchymal transition, leading to cell mobility and metastasis. The decreased sensitivity of hypoxic tumor cells to ionizing radiation is one of the main factors affecting the effect of conventional radiotherapy. It is well known that conventional radiotherapy mainly reduces the effect of hypoxic radiation resistance by reoxygenation between fractions. With the improvement of radiation treatment planning and delivery, more and more cancer patients have been treated with hypofractionated radiotherapy (HFRT), which have achieved a much higher effect than conventional radiotherapy. Given that HFRT is delivered within one or a few fractions, does tumor hypoxia affect its efficacy? Is there any way to further improve the effect of HFRT? In this review, we focus on the interaction between HFRT and hypoxia, and how to optimize the regimen of HFRT to decrease the effect of hypoxia and improve the efficacy is discussed in detail.

J. Soonthornrak, N. Amornwichet, K. Shotelersuk, Dr. K. Saksornchai,
Volume 20, Issue 2 (4-2022)
Abstract

Background: Hypofractionation radiotherapy (HFx) following breast-conserving surgery (BCS) in ductal carcinoma in situ (DCIS) has been shown to be safe in many retrospective studies. In this paper, we report our data and assess those outcomes to support the use of HFx in DCIS. Material and Methods: All patients with DCIS after BCS were treated with 4250cGy in 16 fractions to whole breast with tumor bed boost 1000cGy in 4 fractions. The toxicity was evaluated using CTCAE v.5.0. On the last day of radiation (day 0) then 1 and 6 months post radiation. The cosmesis was evaluated at 6 months. Results: Between July 2018 and December 2019 at our center, 33 patients were analyzed with a median follow up of 7.3 months. No toxicity of more than grade2 occurred. At day 0 and 1 month after radiation, 89% and 85% of patients had grade1 dermatitis and hyperpigmentation, respectively. For induration, 33% had grade1 at day 0, 29% at 1 month, and 44.8% at 6 months. Only 3% had grade2 induration at 1 month. In addition, 67% of the subjects had grade1 pruritus and 37% had grade1 pain at day0. Radiation oncologists assessed good-to-excellent cosmesis in 93% of these patients, while the 96.6% of patients self-evaluated as good to excellent without impact on their self-confidence. Conclusion: This prospective trial showed that HFx can be safely used in DCIS with no more than grade2 skin toxicity and good to excellent cosmesis.

Ph.d., M. Kong, Y.j. Lim,
Volume 20, Issue 3 (7-2022)
Abstract

Background: The optimal inter-fraction interval in fractionated thoracic radiosurgery remains unclear. Several institutions maintain at least a 48-hour interval between each radiosurgery fraction. However, evidence supporting such radiosurgery schedule is lacking. Since 2014, we have performed daily fractionated thoracic radiosurgery without interruption. In this study, we evaluated the safety of daily administration of fractionated thoracic radiosurgery in patients with primary or metastatic lung cancer. Materials and methods: Patients who received radical or salvage fractionated radiosurgery for treatment of primary or metastatic lung cancer were included in this study. All patients received fractionated radiosurgery divided into 2-4 fractions administered daily without interruption. Radiosurgery-induced toxicities were evaluated. Results: Eighty-eight patients and 94 lung masses were treated. Radiosurgery-induced leukopenia and grade 5 toxicity did not occur. One patient experienced radiosurgery-induced grade 4 pneumonitis and dyspnea. Grade 3 pneumonitis, dyspnea, and fatigue developed in 23 (24.5%), 2 (2.1%), and 2 (2.1%) patients, respectively. Four (4.3%) patients experienced rib fracture. Dyspnea, fatigue, nausea, and pneumonitis were more common and severe in patients with central lung lesions. In contrast, dermatitis and rib fracture developed only in patients with peripheral lung lesions. Conclusions: Daily fractionated radiosurgery is safe and well-tolerated in patients with primary or metastatic lung cancer. For patient convenience and better treatment outcomes, daily-fractionated thoracic radiosurgery can be considered.


Page 1 from 1     

International Journal of Radiation Research
Persian site map - English site map - Created in 0.07 seconds with 44 queries by YEKTAWEB 4714