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Showing 24 results for Prostate Cancer
Dr. S.a. Vaezzadeh, M. Allahverdi, H.a. Nedaie, M. Aghili, M. Esfehani,
Volume 10, Issue 3 (12-2012)
Abstract
Background: To evaluate the dosimetric difference
between conventional and three-dimensional
conformal Radiotherapy (3D-CRT) using 6 and 18 MV
X-ray photons. Materials and Methods: Computed
tomography scans of 26 pelvic patients were
acquired and transferred to the 3D treatment
planning system. For each patient, 8 Conventional
plans (3, 4, 5 and 6 Fields) and one 3D-CRT plan
were prepared using 6 and 18 MV photon energies.
The minimum dose (Dmin), maximum dose (Dmax) and
mean dose (Dmean) to target (PTV) and organs at risk
(OAR), Integral dose, Homogeneity Index and
Conformity Index were compared for each plan. Also,
Experimental measurements were performed using
farmer ionization chamber on a patient based pelvic
phantom. Results: On Average, six-field (6F1) plans,
offer minimum dose to critical organs and sufficient
dose to prostate. Increasing the beam energy lead to
a decrease in Dmean of the bladder and femoral
heads, as well as Dmax of PTV. The CI and ID were
decreased by 4% and 11% respectively with
increasing the energy and the number of beams.
Experimental measurements were also in good
agreement with calculations. 3D-CRT reduced Dmean
of bladder, rectum and femoral heads and also CI
and ID were significantly improved by 44.6% and
30.8%, respectively. Conclusion: Increasing the
photon energy and number of beams, improve the
treatment parameters of bladder, femoral heads and
PTV, except the rectum. 3D-CRT offered the most
conformity in the delivery doses to the prostate while
sparing dose to OARs, uninvolved structures with
lower integral dose. Iran. J. Radiat. Res., 2012 10(3‐4):
145‐150
M. Robatjazi, Dr. S.r. Mahdavi, A.r. Nikofar, B. Bolouri, H.r. Baghani,
Volume 12, Issue 4 (10-2014)
Abstract
Background: For the purpose of individual clinical target volume assessment in radiotherapy of prostate cancer, MRSI was used as a molecular imaging modality with MRI and CT images. Materials and Methods: The images of 20 prostate cancer patients were used in this study. The MR and MRSI images were registered with CT ones using non-rigid registration technique. The CT based planning (BP), CT/MRI BP and CT/MRSI BP was performed for each patient. For plan evaluation, Dose Volume Histograms (DVHs) data were used. A paired sample T-test was used for the analysis of the obtained data. Results: The percentage of variation of CTVMRI to CTVCT and PTVMRI to PTVCT were 12.83% and 8.97%, respectively. CTVMRSI and PTVMRSI were 21% and 27.41% more than their corresponding values of CT volumes. The mean percentage of variation in rectum volume that received 60% of the prescribe dose (V60R) in MRSI/CT BP relative to CT BP was 14.66%. Conclusion: The use of MRSI in detecting of prostate adenocarcinoma could provide some decisive information to determine optimum volume and safe margin for target definition to improve adaptive radiotherapy in prostate cancer.
Dr. H.j. Kim, J.h. Phak, W.ch. Kim,
Volume 14, Issue 4 (10-2016)
Abstract
Background: stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for localized prostate cancer. However, prostate-specific antigen (PSA) kinetics after SBRT has not been well characterized. The objective of the current study is to analyze the rate of PSA decline and PSA nadir following hypofractonated SBRT in localized prostate cancer. Materials and Methods: From 2008 to 2014, thirty-nine patients newly diagnosed, localized prostate (25.6% low risk, 66.7% intermediate risk and 7.7% high risk) cancer were treated with SBRT using Cyberknife. Total dose of 36.25 Gy in 5 fractions of 7.25 Gy were administered. No one received androgen deprivation therapy (ADT). PSA nadir and rate of change in PSA (slope) were calculated and compared. Results: With a median follow-up of 52 months (range, 13-71), the median rates of decline of PSA were -0.372, -0.211 and -0.128 ng/mL/month, respectively, for durations of 1, 2 and 3 years after radiotherapy, respectively. The decline of PSA was maximal in the first year and continuously decreased for durations of 2 and 3 year. The median PSA nadir was 0.28 ng/mL after a median 33 months. There was one biochemical failure, occurring in a high risk patient. 5-year actuarial biochemical failure (BCF) free survival was 94.2%. Conclusion: In this report of localized prostate cancer, continuous decrease of PSA level for duration 1, 2 and 3 year following SBRT using Cyberknife resulted in lower PSA nadir. Also, SBRT leaded to long-term favorable BCF-free survival.
S. R. Mahdavi, Dr. E. Jazayeri Gharehbagh , B. Mofid, A. H. Jafari, A. R. Nikoofar,
Volume 15, Issue 1 (1-2017)
Abstract
Background: To correct patient positioning errors (setup errors) during prostate cancer treatment using EPID and fiducial gold markers, to improve the accuracy of the dose delivery in these patients. Materials and Methods: Fifteen patients with localized prostate carcinoma after implantation of fiducial gold markers in their prostate gland underwent the five-field IMRT planning technique. The plan was prepared in accordance with ICRU 50 guidance (PTV to receive 95-107% dose). The software program reconstructed the three-dimensional position of the markers from the different Beams Eye Views (BEV). The discrepancies of the seeds’ positions (prostate surrogate) between plan and daily images were calculated three dimensionally. Then, necessary corrections were applied to match the prostate fiducial markers in the portal image with the BEV image in the planned one by moving the couch in the X, Y and Z directions. Results: Data from 15 patients and 469 fractions of radiotherapy were analyzed in this study. Two sets of data were available from EPID software before and after 3D set-up corrections. The mean of the population displacement in Left /Right (L/R), Anterior/Posterior (A/P) and Crania/Caudal (C/C) directions were 0.5, -1.0 and 2.4mm before, and -0.1, -0.5 and 0.9mm after corrections, respectively. The systematic and random errors for the measured populations in the three mentioned directions were 2.4, 2.7 and 2mm and 6.4, 5.9 and 6.1mm before corrections, and 1.1, 2.4 and 1.4mm and 3.8, 3.9 and 3.6mm after corrections, correspondingly. Conclusion: This study provides further evidence that using gold markers in the prostate improves dose delivery to the prostate. Also, it has been demonstrated that the EPID can be a powerful tool in the reduction of treatment setup errors and the quality assurance and verification of complex treatments.
S.r.m. Mahdavi, E. Jazayeri Gharehbagh, Dr. A.r. Nikoofar, B. Mofid, M. Vasheghani, D. Saedi,
Volume 15, Issue 2 (4-2017)
Abstract
Background: To compare the dosimetric coverage of the planning target volume (PTV) and the dose delivered to the main Organs at Risk (OARs) in 5 and 7-field techniques of Intensity Modulated Radiation Therapy (IMRT) in patients with local prostate cancer. Materials and Methods: Twelve patients with local prostate cancer underwent 5 and 7-field IMRT planning. The delivery of IMRT was carried out using the sliding technique. The dose coverage for PTV was designated to ≥98% of the PTV covered by 95% of the prescribed dose. Dose conformity was evaluated by comparing the volume of nontarget tissue receiving maximum, and average of the prescribed dose and the dose of 33%, 50%, and 66% of the volumes on both planning sets. For target, this evaluation was made with comparing the Conformity Index (CI) and Inhomogeneity Index (HI). In addition, we compared the monitor units used for dose delivery in both planning techniques. Results: All the 5 and 7-field IMRT plans differed slightly in the measured parameters, and none of them have statistically significant differences with each other except for the monitor units where significant differences were observed in favor of the 5-field IMRT plans (p=0.000). In all of the 5-field IMRT plans the mean dose delivered to OARs were very similar or less than that of the 7-field plans. Conclusion: In comparison to the 7-field technique, the 5-field IMRT technique has resulted in improved IMRT dose conformity, homogeneity, and lesser MUs used for radiation therapy. However, this difference was not significant.
Dr. M. Pinkawa, C. Schubert, N. Escobar-Corral, V. Berneking, M.j. Eble,
Volume 16, Issue 2 (4-2018)
Abstract
Background: The aim was to evaluate the benefit of technical advances for treatment planning: introduction of a hydrogel spacer, VMAT (volumetric modulated arc therapy) and a single biological organ at risk objective for the rectum and bladder. Initial standard was a step-and-shoot IMRT (intensity modulated radiotherapy) without a spacer and conventional organ at risk objectives. Materials and Methods: Treatment plans were calculated using IMRT and VMAT techniques before and after spacer injection in 27 patients, respectively. Conventional organ at risk objectives have been used for the optimization of IMRT plans, only a single biological organ at risk objective for VMAT plans. VMAT vs. IMRT plans and plans before vs. after spacer injection were compared. Results: VMAT plans and independently the spacer demonstrated improved dose homogeneity, whereas VMAT additionally displayed improved dose conformity. The dose to the bladder and rectum could be significantly decreased applying the VMAT technique (mean rectum volumes of 14%/10%/5% in VMAT vs. 36%/24%/12% in IMRT within the 50Gy/60Gy/70Gy isodoses; p<0.01). NTCP for ≥grade 3 rectum toxicity could be accordingly decreased with the VMAT technique (3.6 vs. 0.9% for IMRT vs. VMAT; p<0.01) and the spacer gel (3.3 vs. 1.2% for plans without vs. with spacer gel; p<0.01) – only 0.3% with VMAT and spacer gel. Conclusion: In addition to the decreased rectal dose following spacer injection, VMAT with single biological organ at risk optimization resulted in further dose reduction to the organs at risk and improved dose homogeneity and conformity in comparison to the step-and-shoot IMRT technique with conventional objectives.
C.g. Lee, J. Lee, S. Kim, Dr. S.h. You,
Volume 16, Issue 2 (4-2018)
Abstract
Background: This study was designed to suggest the possibility of hormone-related derangement in salvage radiotherapy (SRT) after radical prostatectomy in terms of prostate-specific antigen (PSA) control. Materials and Methods: Among 160 consecutive prostate cancer patients who received radical prostatectomy, 34 with SRT between 2004 and 2012 were retrospectively reviewed. The numbers of patients with pathologic T3-T4 stage, Gleason score 8-10, and positive resection margin were 11 (32.4%), 10 (29.4%), and 17 (50.0%), respectively. Median SRT dose was 64.8 Gy (range, 52.9-70.0 Gy) with 1.8-2.3 Gy fractionations. Biochemical failure-free survival after SRT was counted and the median follow-up period was 32.5 months (range, 10-118 months). Results: After SRT, the median time for PSA to decrease to less than 0.2 ng/mL was four months (range, 0-25 months). The three-year survival rate was 60.3%. On univariate analysis, preferential hormone therapy (PHT) (p=0.022), higher PSA at SRT (p=0.005), and higher PSA after surgery (p=0.003) were related to a shorter biochemical survival period. On multivariate analysis, lower PSA at SRT (p=0.016), higher radiation dose (p=0.007), and non-PHT (p=0.046) suggested a consistent PSA control. Conclusion: According to these results, low PSA values by hormonal intervention need to be reconsidered with a different way to look at the relationship between the PSA and hormone therapy. SRT should be considered for postoperative salvage treatment regardless of the hormone-related PSA values.
S. Maleka, A.m. Serafin, Ph.d J.m. Akudugu,
Volume 17, Issue 1 (1-2019)
Abstract
Background: Radiotherapy and adjuvant androgen deprivation therapy have historically been the first treatment choices for prostate cancer but treatment resistance often limits the capacity to effectively manage the disease. Therefore, alternative therapeutic approaches are needed. Here, the efficacies of radiotherapy and targeting the pro-survival cell signaling components epidermal growth factor receptor (EGFR), phosphoinositide 3-kinase (PI3K), and mammalian target of rapamycin (mTOR), with their respective inhibitors are compared. Materials and Methods: The cytotoxic effects of inhibitors of PI3K and mTOR (NVP-BEZ235) and EGFR (AG-1478), and X-rays, were evaluated in prostate cell lines (LNCaP: cancer; DU145: cancer; BPH-1: benign prostatic hyperplasia; 1542N: apparently “normal”) using a colony forming assay. The cells were exposed to a range of X-ray doses or varying concentrations of the inhibitors, to obtain cell survival curves from which relative sensitivities (RS) of the tumor cell lines were derived as the ratio of their sensitivities to that of the “normal” cell line. Results: The LNCaP cells trended to be more sensitive to X-rays and AG-1478 exposure than 1542N cells, with RS-values of 1.65±0.48 (P=0.1644) and 1.37±0.22 (P=0.0822), respectively. NVP-BEZ235 emerged as very cytotoxic in all tumor cell lines, yielding RS-values of 3.69±0.83 (DU145; P=0.0025), 8.80±1.73 (LNCaP; P<0.0001), and 8.76±1.70 (BPH-1; P=0.0011). Conclusion: These findings demonstrated that targeted therapy, specifically that using NVP-BEZ235, might result in a more effective treatment modality for prostate cancer than conventional radiotherapy.
Ph.d A. Cakir, Z. Akgun, E. Kaytan Saglam,
Volume 17, Issue 2 (4-2019)
Abstract
Background: In the treatment of prostate cancer, radiotherapy is the potential to increase second primary cancers such as bladder and rectal cancers. The reasons for this potential are more monitor units (MUs), therefore a larger total body dose because of leakage radiation, a bigger volume of normal tissue is exposed to lower radiation doses. This study was designed to compare the integral dose of using Flattening Filter (FF) and Flattening Filter-Free (FFF) 6 and 10 MV photon beams via volumetric modulated arc therapy (VMAT) for prostate cancer patients. Materials and Methods: Twenty prostate cancer patients were selected retrospectively for this planning study. VMAT plans were developed using the Eclipse (Varian Medical System, Palo Alto, California, USA) Treatment Planning System (TPS) with 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF for each patient. Conformity index (CI), homogeneity index (HI), Integral dose (ID), the volume receiving 5 Gy (V5%) and monitor units (MUs) were compared. Results: The use of 10 MV FF had 206 liter*Gy integral dose to Body-CTV volume. Using 10 MV FFF had 204 liter*Gy integral dose to normal structures. When 10 MV FF or 10 MV FFF were used instead of 6 MV FF and 6 MV FFF integral dose decreased as -7% and -8%, respectively. The dosimetric difference were statistically significant (p<0.05). The use of 10 MV FFF rather than 10 MV FF had limited influence on the integral dose for rectum, bladder, penile bulb and femoral heads. Conclusion: This study showed that high energy photons (10 MV FF, 10 MV FFF) have lower integral dose than low energy photons (6 MV FF, 6 MV FFF). The relationship between low energies, high energies and integral doses is significant, although there is no significant relationship between V5% doses of all energies. In comparison to different treatment plans, we showed that V5% alone did not provide enough information when possible secondary cancer risks were calculated.
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.
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