RESUMO
The increasing use of new radiopharmaceuticals invites us to reconsider some radiation protection issues, such as the contact restriction time that limits public exposure by nuclear medicine patients. Contact restriction time should be patient specific and conservative, and its assessment made easy for clinicians. Here a method is proposed based on conservative estimation of the whole-body retention function and at least one measurement of the patient's dose rate. Recommended values of the retention function are given for eight therapies:131I (Graves' disease, remnant ablation, patient follow-up, meta-iodobenzylguanidine),177Lu-prostate-specific membrane antigen and177Lu-DOTATATE therapies, and90Y and166Ho microsphere injection of the liver. The patient line source model for scaling dose rate from one distance to another is included in the restriction time calculation. The method is benchmarked against published values and the influence of the dose rate scaling and whole-body retention function illustrated. A spreadsheet is provided, along with the source code, with recommended values for the eight therapies. The recommended values can be changed as well as the dose rate scaling function, and other radiopharmaceuticals can be included in the spreadsheet provided retention functions are defined.
Assuntos
Medicina Nuclear , Proteção Radiológica , Masculino , Humanos , Compostos Radiofarmacêuticos , Radioisótopos do Iodo , Dosagem RadioterapêuticaRESUMO
The decision to irradiate during pregnancy is based on a risk benefit compromise of two kinds: maternal risk and fetal risk. The aim of this work is to determine the foetal risk, and uterine dose measurement in proton therapy. Foetal exposure during treatment is linked to two sources: the treatment phase, and the repositioning phase. An Alderson-Rando anthropomorphic ghost (170cm, 74kg) was positioned on the table in the treatment position. A tissue-equivalent proportional counter (TEPC), adapted to the analysis of complex radiation fields (neutron and photonics), was used to determine the irradiation related to the treatment phase. An AT1123 radiation survey meter was used to measure photons generated by X-ray radiation. I dosimetry was proposed using radio-photoluminescent dosimeters, allowing for a daily check of the dose received in the uterus. The treatment phase produces higher uterine doses than the positioning phase, but these remain very low. The equivalent dose received in the uterus for the entire treatment is estimated at 840 µSv. Using a methodology for measuring the out-of-field dose with pencil beam scanning proton therapy, the foetal dose in the first trimester was well below the acceptance dose of 100 mGy determined by the International Commission on Radiological Protection.
Assuntos
Feto/efeitos da radiação , Posicionamento do Paciente/efeitos adversos , Complicações Neoplásicas na Gravidez/radioterapia , Exposição à Radiação , Útero/efeitos da radiação , Adulto , Feminino , Cabeça/efeitos da radiação , Humanos , Nêutrons , Posicionamento do Paciente/métodos , Imagens de Fantasmas , Fótons , Gravidez , Primeiro Trimestre da GravidezRESUMO
Since the late 2,000 years, under the incentive of the French agencies ANAP (previously MEAH) and HAS and following the decision DC-0103 of the ASN, experience feedback committees (known as 'Comité de retour d'expérience or Crex' in French) have widely been implemented within radiation oncology departments in France. Based on the declaration of error/near misses (precursor events) occurring during medical care to patients, an intuitive method of systematic analysis of these events is basically the aim of such committees (such as the Orion method(©) derived from the air transportation industry). Our article aims at summarizing the paths and pitfalls attached to this methodology, emphasizing what could be the next step, beyond the 'Crex' committees, in the long march to know how to secure care to patients within a radiotherapy medical team.
Assuntos
Neoplasias/radioterapia , Comitê de Profissionais , Humanos , Segurança do Paciente/normas , Radioterapia/efeitos adversos , Radioterapia/normasRESUMO
In August 2013, the French nuclear safety agency (ASN) requested the permanent group of experts in radiation protection in medicine (GPMED) to propose recommendations on the implementation of new technology and techniques in radiation oncology. These recommendations were finalized in February 2015 by the GPMED. In April 2015, the ASN sent a letter to the French ministry of health (DGS/DGOS), and its national health agencies (ANSM, INCa, HAS). In these letters, ASN proposed that, from the 12 recommendations made by the GPMED, an action plan should be established, whose control could be assigned to the French national cancer institute (INCa), as a pilot of the national committee for radiotherapy and that this proposal has to be considered at the next meeting of the national committee of radiotherapy.
Assuntos
Neoplasias/radioterapia , Segurança do Paciente/normas , Radioterapia (Especialidade)/normas , Humanos , Radioterapia/normasRESUMO
PURPOSE: At the request of the French nuclear safety authority (Autorité de Sûreté Nucléaire, ASN) a working party of multidisciplinary experts was initiated to elaborate a report regarding propositions for the clinical practice of stereotactic radiation therapy and the related medical physics. MATERIAL AND METHODS: Several stereotactic radiation therapy experts were audited by the working party, especially neurosurgeons and neuroradiologists, as well as radiation oncologists, medical physicists and radiation technologists. An international survey was conducted looking at legal requirements and guidelines concerning stereotactic radiation therapy. A national survey was conducted in France among 29 departments performing stereotactic radiation therapy. The working party report was submitted for advice to the permanent group of medical experts of ASN. RESULTS: Among the 13 countries who responded, very few have legal documents. Some of them are stating that stereotactic radiation therapy must be performed in a radiotherapy department and only by well-trained professionals. Guidelines describing the role of each participant have been published in the USA. In France, stereotactic radiation therapy is performed with dedicated machines or adapted linear accelerators. In 2009, within the 29 departments, 4247 patients were treated with stereotactic radiation therapy representing 4% of the patients treated with external beam radiation therapy. Intracranial lesions were: 3383 and extracranial: 864. The working party of multidisciplinary experts made 7 recommendations. The first one saying that stereotactic radiation therapy must be considered as a radiotherapy. The permanent group of medical experts is asking to modify the "décret du 19 mars 2007" regarding "radiosurgery". CONCLUSION: The medical benefit of stereotactic radiation therapy is well admitted and it is an increasingly used technique. This work through practical guidelines and legal propositions intends to promote a well-controlled development of this radiotherapy technique.
Assuntos
Radiocirurgia/normas , Gestão da Segurança , Segurança , França , Humanos , Aceleradores de Partículas , Controle de QualidadeRESUMO
PURPOSE OF STUDY: Monte Carlo based treatment planning system are known to be more accurate than analytical methods for performing absorbed dose estimation, particularly in and near heterogeneities. However, the required computation time can still be an issue. The present study focused on the determination of the optimum statistical uncertainty in order to minimise computation time while keeping the reliability of the absorbed dose estimation in treatments planned with electron-beams. MATERIALS AND METHODS: Three radiotherapy plans (medulloblastoma, breast and gynaecological) were used to investigate the influence of the statistical uncertainty of the absorbed dose on the target volume dose-volume histograms (spinal cord, intramammary nodes and pelvic lymph nodes, respectively). RESULTS: The study of the dose-volume histograms showed that for statistical uncertainty levels (1 S.D.) above 2 to 3%, the standard deviation of the mean dose in the target volume calculated from the dose-volume histograms increases by at least 6%, reflecting the gradual flattening of the dose-volume histograms. CONCLUSIONS: This work suggests that, in clinical context, Monte Carlo based absorbed dose estimations should be performed with a maximum statistical uncertainty of 2 to 3%.
Assuntos
Planejamento da Radioterapia Assistida por Computador/métodos , Carga Corporal (Radioterapia) , Mama/efeitos da radiação , Simulação por Computador , Elétrons/uso terapêutico , Feminino , Humanos , Linfonodos/efeitos da radiação , Método de Monte Carlo , Tamanho do Órgão , Dosagem Radioterapêutica , Reprodutibilidade dos Testes , Medula Espinal/efeitos da radiação , IncertezaRESUMO
An evaluation of the conversion process from Hounsfield units (HU) to material composition in computerised tomography (CT) images, employed by the Monte Carlo based treatment planning system ISOgray (DOSIsoft), is presented. A boundary in the HU for the material conversion between "air" and "lung" materials was determined based on a study using 22 patients. The dosimetric consequence of the new boundary was quantitatively evaluated for a lung patient plan.
Assuntos
Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/radioterapia , Método de Monte Carlo , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Dosagem Radioterapêutica , Tomografia Computadorizada por Raios XAssuntos
Tomografia Computadorizada de Feixe Cônico , Imageamento Tridimensional , Aceleradores de Partículas , Radiocirurgia , Tomografia Computadorizada de Feixe Cônico/métodos , Tomografia Computadorizada de Feixe Cônico/normas , França , Imageamento Tridimensional/métodos , Imageamento Tridimensional/normas , Controle de Qualidade , Radiocirurgia/métodos , Radiocirurgia/normas , Dosagem Radioterapêutica , Radioterapia Assistida por Computador/métodos , Radioterapia Assistida por Computador/normasRESUMO
PURPOSE: To study the dose delivered by a megavoltage cone beam computed tomography imaging system (MVCBCT) installed on a Oncor Impression linac (Siemens). MATERIALS AND METHODS: The acquisition of MVCBCT images was modelled in a treatment planning system by 67 photon beams (6 MV). A study was conducted to: compare the calculated and measured dose at the centre of a cylindrical phantom; compare the calculated and measured dose distributions in the Alderson-Rando phantom (pelvis); study the influence of MVCBCT image acquisition for the repositioning of a prostate cancer patient treated by 3D conformal radiotherapy (prescribed dose of 74 Gy), on the dose-volume histograms (DVH) for the treatment plus seven MVCBCT (protocol D1-3 and weekly), treatment plus 37 MVCBCT (one for each day of treatment). RESULTS: The difference between calculated and measured doses at the centre of the cylindrical phantom was less than 3%. A deviation of 7% maximum was found between the dose distribution calculated in the Rando phantom and the measured doses normalized at the beam isocentre. The dose delivered at the isocentre was equal to 3,7 cGy for a "5 MU" protocol, with a maximum dose of 6 cGy. In the case of the patient considered, the acquisition of 37 MVCBCT corresponded to an additional mean dose to the PTV of 1.2 Gy for a protocol "5MU" with a significant influence on the DVH. CONCLUSION: In view of this study, it appears that the doses delivered in frequent use of MVCBCT must be taken into account by the radiation oncologist in assessing the therapeutic dose delivered to the target volume and organs at risk.
Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Imagens de Fantasmas , Neoplasias da Próstata/diagnóstico por imagem , Doses de Radiação , Radioterapia Conformacional/métodos , Cabeça do Fêmur/diagnóstico por imagem , Humanos , Masculino , Aceleradores de Partículas , Pelve/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Reto/diagnóstico por imagem , Bexiga Urinária/diagnóstico por imagemRESUMO
This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve.
Assuntos
Óxido de Alumínio , Carbono , Dosagem Radioterapêutica , Radioterapia , Dosimetria Termoluminescente/instrumentação , Algoritmos , Calibragem , Humanos , Método de Monte Carlo , Aceleradores de Partículas , Temperatura , IncertezaRESUMO
PURPOSE: This paper presents the development of a protocol for quality control of a megavoltage cone beam CT imaging system (MVCB) mounted on a Siemens Oncor 6MV linear accelerator. MATERIALS AND METHODS: Several parameters were controlled on the MVCB system: (1) the initial geometric calibration of the system; (2) the quality of the images (geometric distortion, uniformity, spatial resolution, low contrast resolution) for various protocols; (3) the correspondence between the intensity of voxels and electronic densities; (4) the dose delivered when achieving a MVCB. These tests were done mainly with two cylindrical phantoms specific to the quality control (QC) of a MVCB system, supplied by Siemens, and with the Catphan 600 phantom (The Phantom Laboratory) and Quasar Multipurpose Body phantom (Modus Medical Devices Inc). RESULTS: The results of the quality control of the images were within the tolerances. The use of the Catphan 600 phantom was inadequate for the QC of MVCB images. These tests also highlighted the need to correct the MVCB images for the "cupping artefact" for dose calculation purpose. CONCLUSION: The initial characteristics of the MVCB imaging system were established. Such testing also provided the assessment of the influence of various parameters on the image quality as well as the associated dose delivered during their acquisition, and emphasized the corrections needed to use MVCB images for dose calculation.
Assuntos
Aceleradores de Partículas/normas , Tomografia Computadorizada por Raios X/normas , Calibragem , Humanos , Imagens de Fantasmas , Controle de Qualidade , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: The aim of the present study was to quantitatively assess the performance of a block matching-based automatic registration algorithm integrated within the commercial treatment planning system designated ISOgray from Dosisoft. The accuracy of the process was evaluated by a phantom study on computed tomography (CT), magnetic resonance (MR) and positron emission tomography (PET) images. MATERIALS AND METHODS: Two phantoms were used to carry out this study: the cylindrical Jaszczak phantom and the anthropomorphic Liqui-Phil Head Phantom (the Phantom Laboratory), containing fillable spheres. External fiducial markers were used to quantify the accuracy of 41 CT/CT, MR/CT and PET/CT automatic registrations with images of the rotated and tilted phantoms. RESULTS: The study first showed that a cylindrical phantom was not adapted for the evaluation of the performance of a block matching-based registration software. Secondly, the Liqui-Phil Head Phantom study showed that the algorithm was able to perform automatic registrations of CT/CT and MR/CT images with differences of up to 40 degrees in phantom rotation and of up to 20-30 degrees for PET/CT with accuracy below the image voxel size. CONCLUSION: The study showed that the block matching-based automatic registration software under investigation was robust, reliable and yielded very satisfactory results. This phantom-based test can be integrated into a periodical quality assurance process and used for any commissioning of image registration software for radiation therapy.
Assuntos
Imageamento por Ressonância Magnética/métodos , Imagens de Fantasmas , Tomografia por Emissão de Pósitrons/métodos , Tomografia Computadorizada por Raios X/métodos , Algoritmos , Automação , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Cabeça , Humanos , Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/normas , SoftwareRESUMO
Intra-subject and inter-subject nonlinear registration based on dense transformations requires the setting of many parameters, mainly for regularization. This task is a major issue, as the global quality of the registration will depend on it. Setting these parameters is, however, very hard, and they may have to be tuned for each patient when processing data acquired by different centers or using different protocols. Thus, we present in this article a method to introduce more coherence in the registration by using fewer degrees of freedom than with a dense registration. This is done by registering the images only on user-defined areas, using a set of affine transformations, which are optimized together in a very efficient manner. Our framework also ensures a smooth and coherent transformation thanks to a new regularization of the affine components. Finally, we ensure an invertible transformation thanks to the Log-Euclidean polyaffine framework. This allows us to get a more robust and very efficient registration method, while obtaining good results as explained below. We performed a qualitative and quantitative evaluation of the obtained results on two applications: first on atlas-based brain segmentation, comparing our results with a dense registration algorithm. Then the second application for which our framework is particularly well suited concerns bone registration in the lower-abdomen area. We obtain in this case a better positioning of the femoral heads than with a dense registration. For both applications, we show a significant improvement in computation time, which is crucial for clinical applications.
Assuntos
Encéfalo/anatomia & histologia , Diagnóstico por Imagem/métodos , Algoritmos , Humanos , Processamento de Imagem Assistida por Computador , Planejamento da Radioterapia Assistida por Computador/métodos , Sensibilidade e EspecificidadeRESUMO
Recent advances in radiation oncology are based on improvement in dose distribution thanks to IMRT and improvement in target definition through new diagnostic imaging such as spectroscopic or functional MRI or PET. However, anatomic variations may occur during treatment decreasing the benefit of such optimization. Image-guided radiotherapy reduces geometric uncertainties occurring during treatment and therefore should reduce dose delivered to healthy tissues and enable dose escalation to enhance tumour control. However, IGRT experience is still limited, while a wide panel of IGRT modalities is available. A strong quality control is required for safety and proper evaluation of the clinical benefit of IGRT combined or not with IMRT.
Assuntos
Neoplasias/radioterapia , Radioterapia (Especialidade)/tendências , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada/métodos , Neoplasias Encefálicas/cirurgia , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Neoplasias/diagnóstico , Neoplasias/diagnóstico por imagem , Neoplasias/cirurgia , Neoplasias Pancreáticas/cirurgia , Tomografia por Emissão de Pósitrons , Prostatectomia , Neoplasias da Próstata/radioterapia , Neoplasias da Próstata/cirurgia , Radiocirurgia/instrumentação , Dosagem Radioterapêutica , Robótica , Neoplasias da Coluna Vertebral/cirurgia , Tomografia Computadorizada por Raios X , UltrassonografiaRESUMO
PURPOSE: Virtual simulation process is often used to prepare three dimensional conformal radiation therapy treatments. As the quality of the treatment is widely dependent on this step, it is mandatory to perform extensive controls on this software before clinical use. The tests presented in this work have been carried out on the treatment planning system ISOgray (DOSIsoft), including the delineation module IMAgo and the virtual simulation module SIMAgo. MATERIAL AND METHODS: According to our experience, the most relevant controls of international protocols have been selected. These tests mainly focused on measuring and delineation tools, virtual simulation functionalities, and have been performed with three phantoms: the Quasar Multi-Purpose Body Phantom, the Quasar MLC Beam Geometry Phantom (Modus Medical Devices Inc.) and a phantom developed at Hospital Tenon. RESULTS: No major issues have been identified while performing the tests. These controls have emphasized the necessity for the user to consider with a critical eye the results displayed by a virtual simulation software. The contrast of visualisation, the slice thickness, the calculation and display mode of 3D structures used by the software are many factors of uncertainties. CONCLUSION: A virtual simulation software quality assurance procedure has been written and applied on a set of CT images. Similar tests have to be performed periodically and at minimum at each change of major version.
Assuntos
Simulação por Computador , Garantia da Qualidade dos Cuidados de Saúde , Radioterapia Conformacional , Software , FrançaRESUMO
These last years, the new irradiation techniques as the conformal 3D radiotherapy and the IMRT are strongly correlated with the technological developments in radiotherapy. The rigorous definition of the target volume and the organs at risk required by these irradiation techniques, imposed the development of various image guided patient positioning and target tracking techniques. The availability of these imaging systems inside the treatment room has lead to the exploration of performing real-time adaptive radiation therapy. In this paper we present the different image guided radiotherapy (IGRT) techniques and the adaptive radiotherapy (ART) approaches. IGRT developments are focused in the following areas: 1) biological imaging for better definition of tumor volume; 2) 4D imaging for modeling the intra-fraction organ motion; 3) on-board imaging system or imaging devices registered to the treatment machines for inter-fraction patient localization; and 4) treatment planning and delivery schemes incorporating the information derived from the new imaging techniques. As this paper is included in the "Cancer-Radiotherapie" special volume dedicated to the lung cancers, in the description of the different IGRT techniques we try to present the lung tumors applications when this is possible.
Assuntos
Neoplasias Pulmonares/radioterapia , Radioterapia Assistida por Computador/tendências , Radioterapia Conformacional/tendências , Previsões , Humanos , Imageamento Tridimensional/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/tendências , Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodosRESUMO
The development of conformal radiotherapy techniques (CRT) and intensity modulated CRT requires an accurate delineation of target structures and organs at risk. Thus, additional information provided by anatomical and/or functional imaging modalities can be used for volume of interest determination combined with traditionally used Computed Tomography imaging (CT): for instance, functional or morphological Magnetic Resonance Imaging (f MRI or m MRI) or Positron Emission Tomography (PET). A prerequisite to the simultaneous use of this information is image registration. Due to the differences between the images and the information they provide, a quality control of image registration process for radiotherapy is mandatory. The purpose of this article is to present the difficulties in implementing such controls and to show the necessity for a clinical validation on patient's images. The last part of this work presents the possible interest in using f MRI to help radio-oncologists in the treatment planning for gliomas associated to image coregistration and quality control considerations.
Assuntos
Diagnóstico por Imagem/métodos , Processamento de Imagem Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador , Radioterapia Assistida por Computador , Neoplasias Encefálicas/radioterapia , Diagnóstico por Imagem/normas , Glioma/radioterapia , Humanos , Processamento de Imagem Assistida por Computador/normas , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Controle de Qualidade , Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/normas , Radioterapia Assistida por Computador/métodos , Radioterapia Assistida por Computador/normas , Radioterapia Conformacional , Radioterapia de Intensidade Modulada , Tomografia Computadorizada por Raios XRESUMO
Radiation therapy accelerators require highly accurate dose deposition and the output must be monitored frequently and regularly. Ionization chambers are the primary tool for this control, but their size, their high voltage needed, and the correction needed for electrons make them unsuitable for use during patient treatment. We have developed a small (1-mm-diam and 1-mm-long active part), flexible, and water-equivalent dosimeter. It is suitable for photon and electron beams without corrections, and performs on line dose measurements. This detector is based on only one scintillating fiber and a CCD camera. A new signal processing is used to remove the effect of Cerenkov radiation background, which only requires a preliminary calibration. Central-axis depth-dose distribution comparisons have been achieved with standard ionization chambers, over a range from 8 to 25 MV photons and from 6 to 21 MeV electrons in order to validate this calibration. Results show a very good agreement, with less than 1% difference between the two detectors.