Search results for "Radiotherapy Planning"
showing 10 items of 47 documents
Relapse Analysis of Irradiated Patients Within the HD15 Trial of the German Hodgkin Study Group
2015
Purpose To determine, in the setting of advanced-stage of Hodgkin lymphoma (HL), whether relapses occur in the irradiated planning target volume and whether the definition of local radiation therapy (RT) used by the German Hodgkin Study Group (GHSG) is adequate, because there is no harmonization of field and volume definitions among the large cooperative groups in the treatment of advanced-stage HL. Methods and Materials All patients with residual disease of ≥2.5 cm after multiagent chemotherapy (CTX) were evaluated using additional positron emission tomography (PET), and those with a PET-positive result were irradiated with 30 Gy to the site of residual disease. We re-evaluated all sites o…
Radiation dose distribution in functional heart regions from tangential breast cancer radiotherapy
2015
Abstract Background and purpose To analyze the distribution of individually-determined radiation dose to the heart and its functional sub-structures after radiotherapy in breast cancer patients treated in Germany during 1998–2008. Material and methods We obtained electronic treatment planning records for 769 female breast cancer patients treated with megavoltage tangential field radiotherapy. All dose distributions were re-calculated using Eclipse with the anisotropic analytical algorithm (AAA) for photon fields, and the electron Monte Carlo algorithm for electron boost fields. Based on individual dose volume histograms for the complete heart and several functional sub-structures, we estima…
Measurement of body composition in cancer patients using CT planning scan at the third lumbar vertebra
2019
Objective: the main objective was to assess body composition in terms of skeletal muscle index (SMI), myosteatosis, visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and intermuscular adipose tissue (IMAT) as an adjunct of information provided by radiotherapy CT planning scan. Material and methods: a sample of 49 patients with lung and digestive cancers underwent a CT scan for radiotherapy treatment, which included measurements at the L3 region. Images were analyzed with a radiotherapy contouring software, using different Hounsfield Unit (HU) settings. Cross-sectional areas (cm2) were automatically computed by summing tissue pixels and multiplying by pixel surface area. Low …
Biodosimetry Based on γ-H2AX Quantification and Cytogenetics after Partial- and Total-Body Irradiation during Fractionated Radiotherapy
2015
The aim of this current study was to quantitatively describe radiation-induced DNA damage and its distribution in leukocytes of cancer patients after fractionated partial- or total-body radiotherapy. Specifically, the impact of exposed anatomic region and administered dose was investigated in breast and prostate cancer patients receiving partial-body radiotherapy. DNA double-strand breaks (DSBs) were quantified by γ-H2AX immunostaining. The frequency of unstable chromosomal aberrations in stimulated lymphocytes was also determined and compared with the frequency of DNA DSBs in the same samples. The frequency of radiation-induced DNA damage was converted into dose, using ex vivo generated ca…
Fetal dose measurements and shielding efficiency assessment in a custom setup of (192)Ir brachytherapy for a pregnant woman with breast cancer.
2015
To assess the radiation dose to the fetus of a pregnant patient undergoing high-dose-rate (HDR) (192)Ir interstitial breast brachytherapy, and to design a new patient setup and lead shielding technique that minimizes the fetal dose.Radiochromic films were placed between the slices of an anthropomorphic phantom modeling the patient. The pregnant woman was seated in a chair with the breast over a table and inside a leaded box. Dose variation as a function of distance from the implant volume as well as dose homogeneity within a representative slice of the fetal position was evaluated without and with shielding.With shielding, the peripheral dose after a complete treatment ranged from 50 cGy at…
Monte Carlo simulation of the response of ESR dosimeters added with gadolinium exposed to thermal, epithermal and fast neutrons
2009
Abstract Monte Carlo numerical calculations of the response of alanine and ammonium tartrate ESR (electron spin resonance) dosimeters exposed to neutron fields with different energy spectra are reported. Results have been obtained for various gadolinium concentrations inside the dosimeters. Furthermore, in order to simulate the in-phantom response we have carried out calculations by varying the depth of the dosimeter. We have found that a large enhancement is obtained for thermal neutrons, because of the very high capture cross section of gadolinium to thermal neutrons. A good enhancement was obtained for epithermal neutrons, whereas the sensitivity improvement in the case of fast neutron i…
Intensity-modulated extended-field chemoradiation plus simultaneous integrated boost in the pre-operative treatment of locally advanced cervical canc…
2015
Objective: To investigate the feasibility and determine the recommended pre-operative intensity-modulated radiotherapy (IMRT) dose of extended-field chemoradiation along with simultaneous integrated boost (SIB) dose escalation. Methods: A radiation dose of 40Gy over 4 weeks, 2Gy/fraction, was delivered to the tumour and the lymphatic drainage (planning target volume, PTV3), which encompassed a volume larger than standard (common iliac lymphatic area up to its apex, in front of the L3 vertebra), concurrently with chemotherapy (cisplatin and 5-fluorouracil). Radiation dose was escalated to the pelvis (PTV2) and to the macroscopic disease (PTV1) with the SIB-IMRT strategy. Three dose levels we…
Moderate hypofractionated helical tomotherapy for localized prostate cancer: preliminary report of an observational prospective study.
2019
Objective: To report preliminary findings of a phase II study exploring the clinical outcomes of moderate hypofractionated radiotherapy performed with helical tomotherapy (HT) using computed tomography–magnetic resonance imaging–based planning for localized prostate cancer. Methods: The phase II prospective study received ethics approval from our institutional ethics committee. A dose of 60 Gy/20 fractions for low–intermediate risk prostate cancer by means of HT was explored. Primary endpoints of the study were acute and late gastrointestinal (GI) and genitourinary (GU) toxicities. Secondary endpoints were quality of life and biochemical-free survival. Results: A total of 35 patients were i…
A smart and operator independent system to delineate tumours in Positron Emission Tomography scans
2018
Abstract Positron Emission Tomography (PET) imaging has an enormous potential to improve radiation therapy treatment planning offering complementary functional information with respect to other anatomical imaging approaches. The aim of this study is to develop an operator independent, reliable, and clinically feasible system for biological tumour volume delineation from PET images. Under this design hypothesis, we combine several known approaches in an original way to deploy a system with a high level of automation. The proposed system automatically identifies the optimal region of interest around the tumour and performs a slice-by-slice marching local active contour segmentation. It automa…
Model-Based Dose Calculation Algorithms for Brachytherapy Dosimetry
2019
The purpose of this study was to review the limitations of dose calculation formalisms for photon-emitting brachytherapy sources based on the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) report and to provide recommendations to transition to model-based dose calculation algorithms. Additionally, an overview of these algorithms and approaches is presented. The influence of tissue and seed/applicator heterogeneities on brachytherapy dose distributions for breast, gynecologic, head and neck, rectum, and prostate cancers as well as eye plaques and electronic brachytherapy treatments were investigated by comparing dose calculations based on the TG-43 formalism …