Search results for "Intensity-Modulated"
showing 10 items of 31 documents
Absolute volume of the rectum and AUC from rectal DVH between 25Gy and 50Gy predict acute gastrointestinal toxicity with IG-IMRT in prostate cancer
2016
International audience; Background: To determine whether dose/volume specific endpoints (DVSE) or Area under the rectal DVH curve (rAUC) better predict acute gastrointestinal (GI) toxicity in prostate cancer patients treated with IMRT in the era of daily image guidance (IG-IMRT). Methods: A set of DVSE was recorded from V25 to V75 (increments of 5Gy) (both in % and in cc) for 180 men. The rAUC was calculated for doses ranging between 25Gy and 50Gy (rAUC(25-50)). Univariate and multivariate logistic regressions were performed to determine the relationship between DVSE or rAUC(25-50) and the appearance of any acute GI toxicity. Results: The rates of acute grade 1 (G1), G2 and G3 GI toxicities…
Intensity modulated radiation therapy with simultaneous integrated boost in early breast cancer irradiation. Report of feasibility and preliminary to…
2015
To investigate the feasibility and tolerance in the use of adjuvant intensity modulated radiation therapy (IMRT) and simultaneous integrated boost in patients with a diagnosis of breast cancer after breast-conserving surgery.Between September 2011 to February 2013, 112 women with a diagnosis of early breast cancer (T1-2, N0-1, M0) were treated with IMRT and simultaneous integrated boost after breast-conserving surgery in our institution. A dose of 50Gy in 25 fractions was prescribed to the whole breast and an additional dose of radiation was prescribed on the tumour bed. A dose prescription of 60Gy in 25 fractions to the tumour bed was used in patients with negative margins after surgery, w…
Investigation of correction factors for non-reference conditions in ion chamber photon dosimetry with Monte-Carlo simulations.
2009
Current dosimetry protocols require geometrical reference conditions for the determination of absorbed dose in external radiotherapy. Whenever these geometrical conditions cannot be maintained the application of additional corrections becomes necessary, in principle. The current DIN6800-2 protocol includes a corresponding factor k(NR), but numerical values are lacking and no definite information about the magnitude of this correction is available yet. This study presents Monte-Carlo based calculations within the 6 MV-X photon field of a linear accelerator for a common used ion chamber (PTW31010) employing the EGSnrc code system. The linear accelerator model was matched to measurements, show…
Comparison between transmission and scattering spectrum reconstruction methods based on EPID images.
2013
Numerous improved physics-based methods for Linac photon spectra reconstruction have been published; some of them are based on transmission data analysis and others on scattering data. In this work, the two spectrum unfolding approaches are compared in order to experimentally validate its robustness and to determine which is the optimal methodology for application on a clinical quality assurance routine. Both studied methods are based on EPID images generated when the incident photon beam impinges onto plastic blocks. The distribution of transmitted/scatter radiation produced by this object centered at the beam field size was measured. Measurements were performed using a 6 MeV photon beam p…
SU-E-T-343: Valencia Applicator Commissioning Using a Micro-Chamber Array
2014
Purpose: In the commissioning and QA of surface isotope-based applicators, source-indexer distance (SID) has a great influence in the flatness, symmetry and output. To these purposes, methods described in the literature are the use of a special insert at the entrance of dwell chamber or radiochromic films. Here we present the experience with a micro-chamber array to perform the commissioning and QA of Valencia applicators. Methods: Valencia applicators have been used, the classic and the new extra-shielded version. A micro-chamber array has been employed, 1000 SRS (PTW), with 977 liquid filled, 2.3×2.3×0.5 mm3 sized ion chambers covering 11×11 cm2, which spacing is 2.5 mm in the central 5.5…
A two-dimensional liquid-filled ionization chamber array prototype for small-field verification: characterization and first clinical tests.
2012
In this work we present the design, characterization and first clinical tests of an in-house developed two-dimensional liquid-filled ionization chamber prototype for the verification of small radiotherapy fields and treatments containing such small fields as in radiosurgery, which consists of 2 mm × 2 mm pixels arranged on a 16×8 rectangular grid. The ionization medium is isooctane. The characterization of the device included the study of depth, field-size and dose-rate dependences, which are sufficiently moderate for a good operation at therapy radiation levels. However, the detector presents an important anisotropic response, up to ≃ 12% for front versus near-lateral incidence, which can …
Incidence of mandibular osteoradionecrosis (MORN) after intensity modulated radiotherapy (IMRT) versus 3D conformal radiotherapy (3D-CRT): A systemat…
2022
Background: Analyze the incidence of MORN after head and neck radiotherapy by two novel irradiation techniques. 3DCRT and IMRT and compare the success rates of distinct authors. Material and Methods: An electronic search in Pubmed (MEDLINE), Ovid. Google Scholar and Cochrane Library (Wiley). databases was conducted with the key words Radiotherapy, Conformal[Mesh] OR Radiotherapy. Intensity-Modulated[Mesh]) AND Osteoradionecrosis[Mesh] for all databases. The inclusion criteria randomized controlled trials (RCT), as well as prospective and retrospective cohort studies published in English; MORN patients treated with 3D-CRT y IMRT. Results: 27 articles were selected from 194 initially found. 1…
Quantification of Radiation Biomarkers in Leukocytes of Breast Cancer Patients Treated with Different Modalities of 3D-CRT or IMRT
2016
The goal of this study was to determine whether the quantification of radiation biomarkers in peripheral leukocytes of 111 breast cancer patients after adjuvant treatment with different modalities of three-dimensional conformal radiation therapy (3D-CRT) or intensity-modulated radiation therapy (IMRT) revealed any difference in the patients' radiation burden by out-of-field doses and an associated risk of second malignancies. Whole-breast radiation therapy was performed by 3D-CRT using either a hard wedge (n = 32) or a virtual wedge (n = 49) at dose rates of 3 and 6 Gy per min each. Patients receiving additional radiotherapy to lymph nodes were treated by 3D-CRT (n = 21) or IMRT (n = 9). DN…
Adjuvant volumetric-modulated arc therapy with simultaneous integrated boost in endometrial cancer. Planning and toxicity comparison
2014
Objective. To report dosimetric and acute toxicity data in prospectively enrolled high-intermediate risk endometrial cancer (HIR-EC) patients postoperatively irradiated by simultaneous integrated boost volumetric modulated arc therapy (SIB-VMAT). Methods. Thirty prospectively enrolled HIR-EC patients were postoperatively treated by SIB-VMAT. Target coverage, dose homogeneity, and sparing of organs at risk (OARs) were compared with corresponding data retrieved from an historical control (30 consecutive selected matched patients) treated by concomitant boost three-dimensional conformal radiotherapy (3D CRT CB) from a previously published study (ADA-I trial). All patients received 45 Gy on pel…
Weekly Cisplatin and Volumetric-Modulated Arc Therapy With Simultaneous Integrated Boost for Radical Treatment of Advanced Cervical Cancer in Elderly…
2016
Background: To evaluate the feasibility and clinical preliminary results of weekly cisplatin and volumetric-modulated arc therapy to the pelvis with simultaneous integrated boost to macroscopic disease in a cohort of elderly patients. Materials and Methods: Inclusion criteria of this prospective study were age ≥70 years, Karnofsky performance status 70 to 100, locally advanced histologically proven squamous cervical carcinoma, and patients unable to undergo brachytherapy. Radiation doses prescribed were 66 Gy to the macroscopic disease and 54 Gy to the pelvic nodes in 30 fractions. Weekly cisplatin dose was 40 mg/mq. Results: A total of 30 patients were recruited. Median follow-up was 32 mo…