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Showing 17 results for Conformal
Dr. G. Yavas, C. Yavas, H. Acar,
Volume 10, Issue 3 (12-2012)
Abstract
Background: We aimed to compare field-in-field
technique (FIF) with conformal tangential field radiotherapy
(CRT) in terms of dosimetric benefits for early
stage breast cancer radiotherapy. Materials and
Methods: Twenty consecutive left-side breast cancer
patients who underwent breast-conserving surgery
were included to the study. For each patient, two
different treatment plans were created for the entire
breast. FIF plans and CRT plans were compared for
doses in the planning target volume (PTV), the organ
at risk (OAR) volume including ipsilateral lung, heart,
left ascending coronary artery (LAD) and the
contralateral breast, the homogeneity index (HI), and
the monitor unit (MU) counts required for the
treatment. Paired samples t-test was used for
statistical analysis. Results: The FIF technique
significantly reduced the maximum dose of the PTV
as well as the mean doses of the heart, LAD,
ipsilateral lung and the contralateral breast (p values
were <0.001 for each). When the OAR volumes
irradiated with 2, 5, 10, 20, 30 and 40 Gy were
compared, the results were in favor of the FIF
technique. The volume receiving <20 Gy of the
prescription dose for the ipsilateral lung was
significantly decreased using FIF technique
(p<0.001). FIF technique allowed us more homogenous
dose distribution with lower MUs. Conclusion:
The FIF technique provided better dose distribution in
the PTV and significantly reduced the doses in the
OAR. Considering the lower MUs required for
treatment the FIF technique seems to be more
advantageous than CRT during whole breast
irradiation. Iran. J. Radiat. Res., 2012 10(3‐4): 131‐138
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
Dr. B. Goswami, S. Mitra, S. Banerjee, A. Shiva B, P. Nagendran, P. Kumari, P. Goswami, A. Chakraborty, S. Mukherjee,
Volume 11, Issue 4 (10-2013)
Abstract
Background: Identify the optimal technique of radiotherapy for patients with high grade glioma. Our initial year of experience with RapidArc radiation therapy. Materials and Methods: Planning CT scans of 50 patients with grade IV glioma were reviewed and three plan sets by 3D Conformal Radiotherapy (3DCRT), Intensity Modulated Radiotherapy (IMRT) and Rapid Arc (RA) were generated and the plans were compared. Results: Planning target Volume (PTV) coverage is comparable. However IMRT and RA give better sparing of critical structures. Treatment time and Monitor Units (MU) for Rapid Arc is much less compared to IMRT. Conclusion: If PTV is near to the Organs at Risk (OAR), then IMRT gives good result in comparison to 3DCRT plans. Rapid Arc is faster than IMRT and 3DCRT for same dose prescription to PTV and constraints of OAR.
Dr. M. Izmirli, G. Yilmazer, T. Cakir, Z.a. Palabiyik, M. Nart,
Volume 14, Issue 3 (7-2016)
Abstract
Aims: It was aimed to investigate postoperative conformal radiotherapy planning that provides the best target volume and the least dose for critical organs in cancers of stomach. Methods: This study was conducted on the CT simulation images of thirty patients diagnosed with gastric cancer. Target volumes and the organs at risk were contoured. AP-PA reciprocal parallel field conventional plan and three- and four-field 3D conformal plans were created using linear accelerator. Target volumes and doses consumed by organs at risk were compared by dose-volume histograms. Results: While a sufficient dose could be applied to target volumes in all plans with conformal planning, average figures showed that 95% of porta hepatis area failed to take the prescribed dose (D95) in some plans by using AP-PA reciprocal parallel zone conventional plans. The most convenient protection for spinal cord, heart and kidneys was obtained by conformal four-field technique and the liver doses were increased in conformal four-field plans but did not exceed the tolerance dose. And also, in the conventional AP-PA reciprocal parallel field plans, tolerance dose of spinal cord (4500 cGy) was exceeded. Conclusion: In this study, conformal four-field technique was superior considering target volume dose distributions, and especially spinal cord doses in all localizations and heart doses in cardia tumors. Kidney doses were also reduced in conformal four-field planning, but failed to reach statistical significance. There was a not exceeding tolerance limits dose increase in liver
H. Chen, Dr. H. Huang, G. Li, D. Huang, S. Huang, Z. Wang,
Volume 15, Issue 3 (7-2017)
Abstract
Background: To evaluate computed tomography (CT) and magnetic resonance imaging (MRI) fusion images for delineating gross tumor volume (GTV) in three-dimensional conformal radiotherapy (3D-CRT) of nasophanrygeal carcinoma (NPC), and compare treatment outcomes between CT- and CT+MRI-based targets. Materials and Methods: A total of 120 NPC patients treated with 3D-CRT were included, in which, 60 each were treated with CT-based and 60 with CT+MRI fusion targets. We explored the clinical application of CT+MRI fusion targets and compared the 1-, 3-, and 5-year survival and relapse rates between both targets. Results: The clinical characteristics and treatment factors were well balanced. The differences in public volume using CT alone in the CT+MRI (Group A) and the CT arm (Group B) were not significant (33.6±2.18 vs. 34.3±2.98, P > 0.05). The public volumes of GTV in the two arms were 49.48±2.46 cm3 and 33.6±2.18 cm3 respectively (P < 0.05). CT+MR fusion images did not influence the one-, three-, and 5-year survival rates (100% vs. 98.3%, 85.0% vs. 81.2%, and 73.3% vs. 68.3%, respectively). The three- and 5-year out-of-field progression was reduced in the CT+MRI arm. However, only the difference in 3-year out-of-field relapse rate was significant (3.3% vs. 13.3%; P < 0.05). The incidence of acute toxicities was similar between groups. Conclusion: The variability in GTV delineation in NPC was ascribed to intermodality and not interobserver variability. CT+MR fusion images likely reduced the 3-year out-of-field relapse rate.
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.
A. Shanei, I. Abedi, P. Saadatmand, A.r. Amouheidari, H. Akbari-Zadeh,
Volume 18, Issue 1 (1-2020)
Abstract
Background: The aim of this study was to compare the dosimetric and radiobiological efficiency of various intensity modulated radiotherapy (IMRT) techniques with 3D conventional radiotherapy (3D-CRT) technique in the treatment of early stage oral tongue cancer. Materials and Methods: This study was performed on 38 CT images of patients who were planned with 3D-CRT and three sets of IMRT treatment plans including five, seven and nine fields with prescribed dose of 66 Gy to planning target volume. The dose volume histograms, homogeneity index (HI), conformity index (CI) and normal tissue complication probability (NTCP) of main organs at risk were derived using Prowess Panther treatment planning system. Results: The results of this study indicated an increase in HI and CI for IMRT plans compared to 3D-CRT. Furthermore, IMRT techniques led to a statistically significant reduction in received dose by mandible (up to 10.10 Gy) and thyroid (up to 13.59 Gy) compared to the conventional technique used; whereas, it led to a statistically significant increase in received dose by parotid glands (up to 7.62 Gy) and brain stem (up to 9.87 Gy). In addition, IMRT increased (up to 12.79%) the probability of occurrence of parotid xerostomia and decreased mandibular complications (up to 7.76%) in comparison to conventional treatment. Conclusions: It can be concluded that IMRT can be more successful in improving oral tongue cancer treatment with more conformity and homogeneity. However, IMRT may not be required for all patients with oral tongue cancer at early stage of the disease.
P. Shoa, I. Abedi, Phd., M.b. Tavakoli, A.r. Amouheidari, K. Jabbari,
Volume 18, Issue 1 (1-2020)
Abstract
Background: The use of radiation therapy for medulloblastoma can affect children’s visual system. We estimated children’s visual system complication probability in the craniospinal irradiation (CSI) technique with three-dimensional conformal radiotherapy (3D-CRT). Materials and Methods: CSI of fifteen medulloblastoma patients and a phantom were planned with 6 MV photon beams and 23.4 Gy prescribed dose. The doses of lenses were measured using thermoluminescence dosimeters (TLD). The delivered doses and complication probabilities were calculated based on the equivalent uniform dose (EUD) model to each contoured organ, including the bilateral lenses, optic nerves, retinas and optic chiasm. Results: The received dose for each organ was less than the tolerance value (p<0.001), except for the eye lens. The normal tissue complication probability (NTCP) values for all of the organs at risk (OAR) were found insignificant. The discrepancies of calculated and measured doses for the right and left lenses were 6.35% and 6.23% (p<0.001), respectively. Conclusion: The results of this study showed based on the International Commission on Radiological Protection (ICRP) publication 118 that children with medulloblastoma cancer treated with CSI with 3D-CRT method are susceptible to cataract complication.
A. Shanei, A. Amouheidari, Ph.d., I. Abedi, A. Kazemzadeh, A. Jaafari,
Volume 18, Issue 2 (4-2020)
Abstract
Background: The current study aimed to compare the tumor control probability (TCP) and normal tissue complication probability (NTCP) of three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) for left-sided breast cancer using radiobiological models. Methods: This study was conducted on 30 patients with left-sided breast cancer, who were planned for 3D-CRT and 6-9 fields IMRT treatments using the PROWESS treatment planning system. The planning target volume (PTV) dose of 50 Gy was administered for the 3D-CRT and IMRT plans, respectively. The Niemierko’s equivalent uniform dose (EUD) model was utilized for the estimation of tumor control probability (TCP) and normal tissue complication probability (NTCP). Results: According to the results, the mean TCP values for 3D-CRT, 6-fields IMRT, and 9-fields IMRT plans were 99.07 ±0.07, 99.24 ±0.05 and 99.28 ±0.04, respectively, showing no statistically significant difference. The NTCPs of the lung and heart were considerably lower in the IMRT plans, compared to those in the 3D-CRT plans.
Conclusions: From the radiobiological point of view, our results indicated that 3D-CRT produces a lower NTCP for ipsilateral lung. In contrast, for TCP calculations, there was a higher gain with IMRT plans compared to 3D-CRT plans.
S.m. Hosseini, Phd., M. Momennezhad, Sh. Naseri,
Volume 18, Issue 3 (7-2020)
Abstract
Background: Breast conserving surgery followed by adjuvant whole breast radiotherapy is the accepted treatment in early-stage breast cancer. Due to breast irregularities, it is difficult to achieve homogenous dose distribution with conventional techniques. Currently, it is possible to use varied breast irradiation techniques such as field-in-field (FIF) that is claimed to produce more homogenous distribution of doses within the target volumes while sparing the organs at risk, leading to a better treatment outcome. The present study aimed to compare the conventional and the FIF techniques dosimetrically. Materials and Methods: Twenty patients with early-stage breast cancer underwent computed tomography. Two different treatment plans were created for each patient: the wedge-based (conventional) plan and the FIF plan. Dosimetric parameters and monitor units were compared with paired sample t-test. Results: FIF technique obtained significantly lower dose homogeneity index, lower maximum doses and higher median doses in PTV (P<0.05). Similarly, the conformity index, and mean doses were higher in the FIF technique but the differences were not significant (P>0.05). In ipsilateral lungs, FIF significantly reduced the maximum and mean doses (P<0.05), and showed a tendency to reduce V20 (P>0.05). In patients with left-sided breast cancer, minimum and maximum doses and V40 of heart were significantly decreased in FIF plans (P<0.05). Doses to the contralateral lungs did not differ significantly. Conclusion: These results along with significantly less monitor units required for therapy in FIF suggest that this technique may be more advantageous during breast irradiation.
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