Cowpea ( [L.] Walp., diploid, 2 = 22) is a major crop used as a protein source for human consumption as well as a quality feed for livestock.
View Article and Find Full Text PDFPurpose: The possibility of using the Gafchromic(®) EBT films parallel to incident electron beams was assessed in order to facilitate quality assurance tests for electron dose calculation algorithms.
Materials And Methods: Calibration curves were made for electron energies of 6, 9 and 12MeV. A set-up was suggested for EBT film irradiation parallel to the beam, and the dose measurements were compared to Ionization Chamber (IC) measurements in standard and small electrons beams.
Disseminating the knowledge and lessons learned from accidental exposures is crucial in preventing re-occurrence. This is particularly important in radiation therapy; the only application of radiation in which very high radiation doses are deliberately given to patients to achieve cure or palliation of disease. Lessons from accidental exposures are, therefore, an invaluable resource for revealing vulnerable aspects of the practice of radiotherapy, and for providing guidance for the prevention of future occurrences.
View Article and Find Full Text PDFThis study was designed to measure organ absorbed doses from multi-detector row computed tomography (MDCT) on pediatric anthropomorphic phantoms, calculate the corresponding effective doses, and assess the influence of automatic exposure control (AEC) in terms of organ dose variations. Four anthropomorphic phantoms (phantoms represent the equivalent of a newborn, 1-, 5-, and 10-y-old child) were scanned with a four-channel MDCT coupled with a z-axis-based AEC system. Two CT torso protocols were compared: a first protocol without AEC and constant tube current-time product and a second protocol with AEC using age-adjusted noise indices.
View Article and Find Full Text PDFThis study assessed and compared various image quality indices in order to manage the dose of pediatric abdominal MDCT protocols and to provide guidance on dose reduction. PMMA phantoms representing average body diameters at birth, 1 year, 5 years, 10 years and 15 years of age were scanned in a four-channel MDCT with a standard pediatric abdominal CT protocol. Image noise (SD, standard deviation of CT number), noise derivative (ND, derivative of the function of noise with respect to dose) and contrast-to-noise ratio (CNR) were measured.
View Article and Find Full Text PDF(18)F-fluoro-deoxy-glucose ((18)F-FDG) positron emission tomography (PET) is one of the most sensitive and specific imaging modalities for the diagnosis of non-small cell lung cancer. A drawback of PET is that it requires several minutes of acquisition per bed position, which results in images being affected by respiratory blur. Respiratory gating techniques have been developed to deal with respiratory motion in the PET images.
View Article and Find Full Text PDFPurpose: The aim of this study was to analyze overall and relapse-free survival in a cohort of 809 patients, 34% of whom corresponded to a higher-risk group than American Brachytherapy Society (ABS) criteria.
Methods And Materials: Between January 1999 and September 2004, 809 patients were treated with permanent loose 125 iodine seed implantation (IsoSeed Bebig, Eckert and Ziegler) by the Paris Institut Curie, Cochin Hospital, and Necker Hospital group. Of these 809 patients, 533 (65.
Automatic exposure control (AEC) systems have been developed by computed tomography (CT) manufacturers to improve the consistency of image quality among patients and to control the absorbed dose. Since a multichannel helical CT scan may easily increase individual radiation doses, this technical improvement is of special interest in children who are particularly sensitive to ionizing radiation, but little information is currently available regarding the precise performance of these systems on small patients. Our objective was to assess an AEC system on pediatric dose phantoms by studying the impact of phantom transmission and acquisition parameters on tube current modulation, on the resulting absorbed dose and on image quality.
View Article and Find Full Text PDFA French decree of February 3rd 2005, allowed the Iodin 125 seeds from several companies to be reimbursed after a permanent implantation brachytherapy for a prostate cancer. Within this frame, the French "Comité économique des produits de santé" (CEPS; Economic committee for health products) made mandatory the annual writing and publication of a follow-up study with three main aims; make sure that the seeds were used for prostate cancer patients with criterias corresponding to the national recommendations, analyze the quality of the dosimetric data, and report all side effects, complications and possible accidents. We therefore report here a clinical and dosimetric analysis of 469 patient cases treated in France in nine centers in 2005 with the Iodin 125 IsoSeed Bebig.
View Article and Find Full Text PDFRespiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart..
View Article and Find Full Text PDFA dynamic lung tumor phantom was used to investigate the geometric reconstruction accuracy of a commercial four-dimensional computed tomography (4D-CT) system. A ball filled with resin, embedded in a cork cube, was placed on a moving platform. Various realistic antero-posterior (AP) motions were programmed to reproduce the respiratory motion of a lung tumor.
View Article and Find Full Text PDFThe objective of this study was to evaluate set-up uncertainties using a portal imaging system in a population of inoperable non-small cell lung cancer. Twenty-one patients were treated by a conformal radiotherapy technique with a personalized immobilization cast. The beam was verified by comparison with a corresponding digitally reconstructed radiograph by superimposition of anatomical structures.
View Article and Find Full Text PDFPurpose: To assess the frequency of the PSA "bouncing" phenomenon after a significant follow-up in a series of patients treated by permanent implant brachytherapy for a prostate cancer. To look for the clinical and dosimetric parameters possibly linked to this transitory secondary PSA increase. To evaluate in which percentage of cases this bouncing could have mimicked a biochemical relapse according to the ASTRO consensus criteria.
View Article and Find Full Text PDFBreathing can lead to organ motions up to several centimeters. For radiotherapy of lung, these motions are generally taken into account by adding a specific margin around the target. Thus, treated volumes are often too large to allow for the high-dose values requested for local control.
View Article and Find Full Text PDFWhereas it has been proposed almost one century ago, brachytherapy for prostate cancer has only recently emerged, especially thanks to endorectal echography, allowing to visualize seed implantation, to the development of seeds for permanent delivery and of micro-sources for high-dose rate delivery, and also to the development of three-dimension dosimetry programs allowing real-time implantations. For selected patients with localized prostate cancer (PSA < 10, Gleason < 7, no extracapsular extension, volume < 50-60 g), prostate brachytherapy with permanent implants (iodine 125 or, less frequently, palladium 103) gives results which appear at 10-15 years comparable to those of surgery. Incontinence and impotence rates appear lower than those of classical surgery.
View Article and Find Full Text PDFBreast radiotherapy is a technical challenge in women with pectus excavatum. We aim to assess isocentric lateral decubitus (ILD) technique as a means to irradiate breasts for patients with pectus excavatum. Four women presenting with left-sided breast cancers and found to have pectus excavatum were offered breast-conserving treatments.
View Article and Find Full Text PDFWe have designed a simple benchmark test for the user of a treatment planning system to check the calculation algorithm's ability to model the build up effect beyond an air/tissue interface. The expected result is expressed as an inhomogeneity correction factor CF derived from measurements and from Monte Carlo calculations for a full range of photon beam qualities. The linear regression lines obtained from plotting CF as a function of beam quality index form the basis for a quantitative check of the algorithm performance.
View Article and Find Full Text PDFPurpose: To assess the frequency and features of the PSA bounce phenomenon in a series of patients treated with permanent implant brachytherapy for prostate cancer, and to evaluate the percentage of cases in which this bounce could have mimicked a biochemical relapse according to the American Society for Therapeutic Radiology and Oncology consensus criteria.
Methods And Materials: From January 1999 to December 2001, 295 patients were treated with a permanent prostate implantation (real-time technique, with free (125)I seeds) by the Paris Institut Curie/Hospital Cochin/Hospital Necker Paris group. Duration of followup is 40.
Today, electronic portal imaging devices (EPIDs) are widely used as a replacement to portal films for patient position verification, but the image quality is not always optimal. The general aim of this study was to optimize the acquisition parameters of an amorphous silicon EPID commercially available for clinical use in radiation therapy with the view to avoid saturation of the system. Special attention was paid to selection of the parameter corresponding to the number of rows acquired between accelerator pulses (NRP) for various beam energies and dose rates.
View Article and Find Full Text PDFA number of treatment-planning systems still use conventional correction methods for body inhomogeneities. Most of these methods (power law method, tissue-air ratio (TAR), etc.) consider only on-axis points, rectangular fields, and inhomogeneous slabs covering the whole irradiating field.
View Article and Find Full Text PDFCancer Radiother
November 2005
Adjuvant Radiotherapy has been shown to significantly reduce locoregional recurrence but this advantage is associated with increased cardiovascular and pulmonary morbidities. All uncertainties inherent to conformal radiation therapy must be identified in order to increase the precision of treatment; misestimation of these uncertainties increases the potential risk of geometrical misses with, as a consequence, underdosage of the tumor and/or overdosage of healthy tissues. Geometric uncertainties due to respiratory movements or set-up errors are well known.
View Article and Find Full Text PDFBreast radiotherapy is still in progress. The target volumes - whole breast and lymph nodes - are usually located by clinical palpation and the use of bony landmarks. However computed tomography has allowed a better definition of the deep edge of the volumes and the calculation of 3D dose distributions.
View Article and Find Full Text PDFInt J Radiat Oncol Biol Phys
October 2005
Purpose: To assess the validity of gated radiotherapy of lung by using a cross-check methodology based on four-dimensional (4D)-computed tomography (CT) exams. Variations of volume of a breathing phantom was used as an indicator.
Methods And Materials: A balloon was periodically inflated and deflated by a medical ventilator.
Purpose: To present an original technique for breast radiotherapy, with the aim of limiting lung and heart irradiation, satisfying quality assurance criteria.
Methods And Material: An original radiotherapy technique for breast irradiation has been developed at the Institute Curie in January 1996. It consists of isocentric breast irradiation in the lateral decubitus position (isocentric lateral decubitus [ILD]).
Respiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart..
View Article and Find Full Text PDF