1,721,285 research outputs found
Number of potential patients to be treated with proton therapy in Italy
No full textIn radiotherapy, the use of proton beams is one of the most promising approaches in order to reduce the treatment volume and, consequently, increase the total dose avoiding severe complications to the normal tissues surrounding the target. Among the new hospital-based facilities that are planned for the next future, the italian project is in an advanced stage of study. Because of the complexity and high cost of the italian centre, one of the most important information in order to establish the cost/benefit balance, is represented by the number of potential patients to be treated for the various pathologies. For this reason it is useful to define a priority scale of clinical indications and, on this basis, to estimate the yearly patient afflux to the center, taking into account the incidence and the expected new cases to be treated with protons. Indications have been divided into two categories, according to decreasing priority. Category A includes all the tumors in which the use of proton therapy has clearly demonstrated to be advantageous, being the only way to give a curative dose to the target. In Italy, the extimated number of this category of patients is 825 each year. Category B comprises a great variety of tumors characterized mainly by a local evolution, with a limited likelihood of distant spread, and therefore potentially cured if the local control can be obtained. The total number of potential patients in this category is more than 10,000
Medical aspects of the National Centre for Oncological Hadrontherapy (CNAO - Centro Nazionale Adroterapia Oncologica)
No full textMore than 20 hadrontherapy centres are active in the world and about 40,000 patients have been treated, almost 4000 with ions. Physical selectivity and high relative biologic efficiency (RBE) represent the rationale for using ions in the treatment of tumours. The clinical results are very promising and justify the construction of new centres. We present the main characteristics of CNAO (Centro Nazionale Adroterapia Oncologica) and its possible integration in a nationwide network. The Italian project started in 1991 thanks to the activity of the TERA Foundation and was financed by the Italian Government in 2002. The CNAO will be built in Pavia to start clinical activity in 2007. The equipment will include a synchrotron and 3 treatment rooms mainly devoted to carbon ions but able to deliver also protons. The Centre should be able to deliver up to 20,000 fractions / year. The realization of CNAO is part of a more ambitious project to set up an integrated national network. The need of hadrontherapy centres is defined by epidemiological studies based on Italian tumour registries showing that almost 900 patients can be electively treated with protontherapy and about 10,000 could be included in clinical trials. Considering that ions could be used for radioresistant tumours that affect about 25,000 new patients/year, we estimate that 10-15%, i.e. 3000-4000 patients would benefit from ion therapy. The realization of a nationwide network possibly linked to a larger European network will be very helpful in making available hadrontherapy for a large part of the population
Assessment of the accuracy of position in breast irradiation with isocentric technique using an electronic system to acquire portal images.
No full textThis study investigated the accuracy of daily patient positioning in an isocentric set-up for breast irradiation. This was achieved through the assessment of both systematic and random errors measured as discrepancies between reference simulation images and portal images obtained with an on-line electronic portal imaging device (EPID). To this end, 10 portal images for each of the tangential fields were obtained in 12 consecutive patients and the images were compared to reference simulation films with dedicated software tools provided with the EPID. The discrepancies measured for each set of images were analyzed statistically. Most variations in each series both in terms of cranio-caudal and of lateral displacement appeared to be random, with mean standard deviations of 2.3 and 2.8 mm, respectively. Such variations between reference fields and portal images tend to counteract one another and do not usually play a significant role in the overall accuracy of patient set-up. In some cases, however, the distribution of the variations occurred in a well-defined pattern indicating a systematic error in patient positioning. This study shows that our set-up technique for breast irradiation is relatively accurate and reproducible, and most of the observed errors were below the 5 mm cut-off level, but it stresses the need of accurate quality assurance programs in radiotherapy. Electronic portal imaging devices are excellent tools for fast portal image acquisition, and permit the accurate assessment of discrepancies with respect to reference images
Radiotherapy of liver malignancies: from whole liver irradiation to stereotactic hypofractionated radiotherapy
No full textUntil recently radiotherapy of hepatic malignancies has played a limited role due to the well-known limited radiotolerance of the liver. The aim of this paper is to review the available data on the risk of radiation-induced liver disease (RILD) and to define the modern role of radiotherapy in the management of patients with metastatic or primary liver malignancies.
METHODS:
The advent of three-dimensional conformal treatment planning with dose-volume histogram analysis has made the study of partial liver irradiation possible. Limited portions of the liver may withstand high doses of radiation with minimal risk of RILD. Patients with solitary unresectable liver tumors may be treated with high-dose radiotherapy with curative intent. Recently, the feasibility of stereotactically guided treatment techniques with a single fraction or few treatment sessions has been explored in numerous institutions.
RESULTS:
The radiation tolerance of the whole liver found by several investigations is in the order of approximately 30 Gy, which seriously restricts its clinical application. The role of whole liver irradiation therefore appears of limited benefit in the palliation of patients with multiple liver metastases. The use of three-dimensional conformal techniques has made partial liver irradiation possible to doses in the 70-80 Gy range with conventional fractionation. At least two published series have reported improved local control and survival rates with dose escalation with three-dimensional conformal radiotherapy in patients with unresectable liver metastases. Similar outcomes have been recently reported with single dose (or hypofractionated) stereotactic radiotherapy both in metastatic and primary hepatic malignancies with minimal morbidity. Accurate target delineation and treatment reproducibility are the key to the success of this novel treatment approach, and specific treatment planning techniques and patient setup procedures must be developed to implement it.
CONCLUSIONS:
Stereotactic high-dose radiotherapy is technically feasible for the treatment of inoperable liver malignancies, with the potential of high local control and low morbidity. Definitive evidence on the clinical advantages of this technique over other more established treatments can only be gathered from well-designed clinical studie
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Particle Beam Therapy (Hadrontherapy): Basis for interest and Clinical Experience
No full textThe particle or hadron beams deployed in radiotherapy (protons, neutrons and helium, carbon, oxygen and neon ions) have physical and radiobiological characteristics which differ from those of conventional radiotherapy beams (photons) and which offer a number of theoretical advantages over conventional radiotherapy. After briefly describing the properties of hadron beams in comparison to photons, this review discusses the indications for hadrontherapy and analyses accumulated experience on the use of this modality to treat mainly neoplastic lesions, as published by the relatively few hadrontherapy centres operating around the world. The analysis indicates that for selected patients and tumours (particularly uveal melanomas and base of skull/spinal chordomas and chondrosarcomas), hadrontherapy produces greater disease-ti ee survival. The advantages of hadrontherapy are most promisingly realised when used in conjunction with modern patient positioning, radiation delivery and focusing techniques (e.g. on-line imaging, three-dimensional conformal radiotherapy) developed to improve the efficacy of photon therapy. Although the construction and running costs of hadrontherapy units are considerably greater than those of conventional facilities, a comprehensive analysis that considers all the costs, particularly those resulting from the failure of less effective conventional radiotherapy, might indicate that hadrontherapy could be cost effective. En conclusion, the growing interest in this form of treatment seems to be fully justified by the results obtained to date, although more efficacy and dosing studies are required. (C) 1998 Elsevier Science Ltd. All rights reserved
Review of current protocols for protontherapy in USA
No full textThe basis for interest in proton beams by clinical radiation oncologists lies in reduction in treatment volume. The yields from employing a smaller treatment volume are the increase of tumor control probability and the reduction of normal tissues complication probability. The clinical use of proton therapy began in 1954 at Uppsala University in Sweden and in 1961 at Harvard Cyclotron Laboratory in Boston, USA, So far, the total number of worldwide patients treated by protons is about 20,000. In this paper attention will be given to the treatment of patients at the Massachusetts General Hospital-Massachusetts Eye and Ear Infirmary-Harvard Cyclotron Laboratory, and at the Loma Linda University Medical Center. In particular, a review of the literature about the techniques and the results of treatment of skull base and cervical spine chordoma and low grade chondrosarcoma, skull base meningioma, pituitary tumors, paranasal sinus carcinoma, glioblastoma multiforme, artero-venous malformations, uveal melanoma, macular degeneration, retinoblastoma, thoracic spine-sacrum tumors, and prostate carcinoma Is presented. In order to verify and improve the clinical results, the conduct of prospective trials on an inter-institutional basis is essential. To facilitate the conduct of such studies the US National Cancer Institute and the American College of Radiology have established the Proton Therapy Oncology Group (PROG). Several phase III and some phase I-II trials are active at the Massachusetts General Hospital, Harvard Cyclotron Laboratory, and at the Loma Linda University Medical Center
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