Cancer and cardiovascular disease (CVD) are the leading cause of mortality worldwide, and breast cancer (BC) the most common malignancy affecting women worldwide. Radiotherapy is an important ...component of BC treatment and participates in CVD occurrence. It seems, therefore, crucial to gather both radiation oncology and cardiology medical fields to improve the follow-up quality of our BC patients. This review aims at updating our knowledge regarding cardiotoxicities risk factors, and consequently, doses constraints in case of 3D-conformal and IMRT treatment planning. Then we will develop how to reduce cardiac exposure and what kind of cardiac follow-up we could recommend to our breast cancer patients.
À travers le monde, les cancers et les maladies cardiovasculaires sont les principales causes de mortalité, et le cancer du sein le principal cancer affectant les femmes. La radiothérapie est un élément majeur dans la prise en charge thérapeutique des patientes atteintes d’un cancer du sein et contribue au risque d’apparition de maladies cardiovasculaires. Il semble donc essentiel de regrouper les disciplines de radiothérapie oncologique et de cardiologie afin d’améliorer la qualité de la surveillance des patientes traitées pour un cancer du sein. Les objectifs de cette revue de la littérature sont de mettre à jour nos connaissances concernant les facteurs de risque de cardiotoxicités et par conséquent des contraintes de dose en cas de planification de radiothérapie conformationnelle tridimensionnelle ou de RCMI. Sont également abordés les outils pour réduire l’exposition cardiaque ainsi que les recommandations actuelles du suivi cardiologique pour ces patientes.
Radiation therapy in the thoracic region may deliver incidental ionizing radiation to the surrounding healthy structures, including the heart. Radio-induced heart toxicity has long been a concern in ...breast cancer and Hodgkin's lymphoma and was deemed a long-term event. However, recent data highlight the need to limit the dose to the heart in less favorable thoracic cancers too, such as lung and esophageal cancers in which incidental irradiation led to increased mortality. This article will summarize available cardiac dose constraints in various clinical settings and the types of radio-induced cardiovascular diseases encountered as well as delineation of cardiac subheadings and management of cardiac devices. Although still not completely deciphered, heart dose constraints remain intensively investigated and the mean dose to the heart is no longer the only dosimetric parameter to consider since the left anterior descending artery as well as the left ventricle should also be part of dosimetry constraints.
La radiothérapie dans la région thoracique peut inopinément délivrer de la dose dans les structures saines environnantes incluant le cœur. La toxicité cardiaque radio-induite est depuis longtemps une préoccupation dans la prise en charge des cancers du sein et de la maladie de Hodgkin et était considérée comme un évènement à long terme. Cependant, des données plus récentes soulignent la nécéssité de limiter également la dose dans le cœur au cours du traitement des cancers thoraciques de pronostic moins favorable, comme les cancers du poumon et de l’œsophage où l’irradiation incidentelle a provoqué une augmentation de la mortalité. Cet article résume les contraintes de dose cardiaque disponibles dans différentes situations cliniques et les types de maladies cardiovasculaires radio-induites rencontrés ainsi que la problématique de la délinéation des sous-structures cardiaques et de la gestion des dispositifs cardiaques implantables. Bien qu’encore incomplètement décryptées, les contraintes de dose cardiaque font actuellement l’objet d’investigations intenses et la dose moyenne dans le cœur n’est désormais plus le seul paramètre dosimétrique à considérer. En particulier, les doses dans l’artère interventriculaire antérieure et le ventricule gauche devraient aussi faire partie des contraintes dosimétriques.
•A new POD–ROM formulation based on residual minimization is proposed.•Two flows types are investigated: a transient flow and a periodic shear flow.•The obtained results are compared to those arising ...from other ROM approaches.•The new model enables to increase the velocity and pressure fields accuracy.
The pressure term which appears in the ROM (reduced order model) associated to the incompressible Navier–Stokes equations, in particular for the shear flows, plays an important role on the velocity. The aim of this paper is to propose a Proper Orthogonal Decomposition based reduced order model (POD–ROM) to obtain both the velocity and pressure fields for incompressible flows. Two PODs are performed, one for the velocity and the other for the pressure. Contrary to existing projection methods available in the literature, the temporal velocity and pressure coefficients are sought by minimizing the residual of the momentum equation only, without the need of a Poisson equation. For the numerical test cases considered in this paper, the proposed minimum residual projection enables to obtain accurately the pressure field, and in turn to slightly improve the velocity one. The method is tested on two fluid flows: a transient mixed-convection flow and a periodic flow around a circular cylinder. In this last case, the drag, lift and pressure coefficients, as well as the Strouhal number are properly recovered compared to those of the full model.
Purpose
Small field dosimetry for radiotherapy is one of the major challenges due to the size of most dosimeters, for example, sufficient spatial resolution, accurate dose distribution and energy ...dependency of the detector. In this context, the purpose of this research is to develop a small size scintillating detector targeting small field dosimetry and compare its performance with other commercial detectors.
Method
An inorganic scintillator detector (ISD) of about 200 µm outer diameter was developed and tested through different small field dosimetric characterizations under high‐energy photons (6 and 15 MV) delivered by an Elekta Linear Accelerator (LINAC). Percentage depth dose (PDD) and beam profile measurements were compared using dosimeters from PTW namely, microdiamond and PinPoint three‐dimensional (PP3D) detector. A background fiber method has been considered to quantitate and eliminate the minimal Cerenkov effect from the total optical signal magnitude. Measurements were performed inside a water phantom under IAEA Technical Reports Series recommendations (IAEA TRS 381 and TRS 483).
Results
Small fields ranging from 3 × 3 cm2, down to 0.5 × 0.5 cm2 were sequentially measured using the ISD and commercial dosimeters, and a good agreement was obtained among all measurements. The result also shows that, scintillating detector has good repeatability and reproducibility of the output signal with maximum deviation of 0.26% and 0.5% respectively. The Full Width Half Maximum (FWHM) was measured 0.55 cm for the smallest available square size field of 0.5 × 0.5 cm2, where the discrepancy of 0.05 cm is due to the scattering effects inside the water and convolution effect between field and detector geometries. Percentage depth dose factor dependence variation with water depth exhibits nearly the same behavior for all tested detectors. The ISD allows to perform dose measurements at a very high accuracy from low (50 cGy/min) to high dose rates (800 cGy/min) and was found to be independent of dose rate variation. The detection system also showed an excellent linearity with dose; hence, calibration was easily achieved.
Conclusions
The developed detector can be used to accurately measure the delivered dose at small fields during the treatment of small volume tumors. The author's measurement shows that despite using a nonwater‐equivalent detector, the detector can be a powerful candidate for beam characterization and quality assurance in, for example, radiosurgery, Intensity‐Modulated Radiotherapy (IMRT), and brachytherapy. Our detector can provide real‐time dose measurement and good spatial resolution with immediate readout, simplicity, flexibility, and robustness.
Uncertainty quantification is crucial for any measurement technique. The present work aims at validating a priori estimates of displacement uncertainties. Images acquired prior to fourteen ...thermomechanical tests were analyzed via FE-based stereocorrelation to determine actual displacement uncertainties, which were compared to a priori estimates. For the studied experimental database, a very good agreement was observed between a priori and a posteriori estimates of standard displacement uncertainties.
To report complications, failure rate, and esthetic results in patients undergoing immediate breast reconstruction with a tissue expander and implant, with or without adjuvant treatment.
We reviewed ...the records of the 77 patients who underwent immediate breast reconstruction with an expander/implant between January 1999 and December 2000. Complications were assessed using the Common Toxicity Criteria, version 2, scale. Esthetic results were assessed by the physician using five criteria.
Of the 77 patients, 55 had received adjuvant radiotherapy. The median follow-up was 25 months. Complications appeared to correlate with radiotherapy (14% for nonirradiated patients; 51% for irradiated patients;
p = 0.006) and adjuvant chemotherapy (54% with chemotherapy CHT vs. 25% without CHT;
p = 0.02). Breast reconstruction failed in 21% of patients (9% of nonirradiated patients and 24% of irradiated patients;
p = 0.1), and chemotherapy was associated with a worse rate of failure (34% with CHT vs. 6% without CHT,
p = 0.005). Adjuvant tamoxifen, however, correlated neither with complications (45% with tamoxifen vs. 39% without;
p = 0.15) nor with failure (21% with tamoxifen and 23% without,
p = 0.79). Esthetic results were acceptable in 60% of cases.
Immediate breast reconstruction with an expander/implant can be considered even for patients requiring adjuvant treatment. However, the complication and failure rates are three times higher after postexpander radiotherapy.
We developed a high spatial resolution and sensitive detector particularly suitable for radiation dose measurements in radiotherapy at small fields and X-ray imaging applications. The detector is ...based on a silica optical fiber whose sensitive terminal is functionalized by grafting Ag-doped ZnS scintillating materials that emit blue luminescence under X-ray irradiation. Due to the small scintillating head of the detector, the acquisition signal is quite low, and it is measured by a sensitive photon counter plugged at the other terminal of the fiber. The weaker signal can be enhanced significantly by adding a metal coating over the scintillator. Therefore, this study presents the effect of metal thickness and density on the signal amplification at high irradiation energies of 6 MeV and 15 MeV using a Linear Accelerator (LINAC). In addition, the stem effect was characterized for regular to small field beam size and shows that the detector is almost free from stem contribution during high energy irradiation.
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