RESUMO
With the expansion of proton radiation therapy centers across the United States and a gradually expanding body of academic evidence supporting its use, more patients are receiving-and asking about-proton therapy than ever before. Here, we outline, for nonradiation oncologists, the theoretical benefits of proton therapy, the clinical evidence to date, the controversies affecting utilization, and the numerous randomized trials currently in progress. We also discuss the challenges of researching and delivering proton therapy, including the cost of constructing and maintaining centers, barriers with insurance approval, clinical situations in which proton therapy may be approached with caution, and the issue of equitable access for all patients. The purpose of this review is to assist practicing oncologists in understanding the evolving role of proton therapy and to help nonradiation oncologists guide patients regarding this technology.
Assuntos
Terapia com Prótons , Terapia com Prótons/métodos , Terapia com Prótons/tendências , Humanos , Neoplasias/radioterapiaRESUMO
In the current spectrum of cancer treatments, despite high costs, a lack of robust evidence based on clinical outcomes or technical and radiobiological uncertainties, particle therapy and in particular proton therapy (PT) is rapidly growing. Despite proton therapy being more than fifty years old (first proposed by Wilson in 1946) and more than 220,000 patients having been treated with in 2020, many technological challenges remain and numerous new technical developments that must be integrated into existing systems. This article presents an overview of on-going technical developments and innovations that we felt were most important today, as well as those that have the potential to significantly shape the future of proton therapy. Indeed, efforts have been done continuously to improve the efficiency of a PT system, in terms of cost, technology and delivery technics, and a number of different developments pursued in the accelerator field will first be presented. Significant developments are also underway in terms of transport and spatial resolution achievable with pencil beam scanning, or conformation of the dose to the target: we will therefore discuss beam focusing and collimation issues which are important parameters for the development of these techniques, as well as proton arc therapy. State of the art and alternative approaches to adaptive PT and the future of adaptive PT will finally be reviewed. Through these overviews, we will finally see how advances in these different areas will allow the potential for robust dose shaping in proton therapy to be maximised, probably foreshadowing a future era of maturity for the PT technique.
Assuntos
Previsões , Neoplasias/radioterapia , Terapia com Prótons/tendências , Institutos de Câncer , Ciclotrons , Humanos , Análise de Ativação de Nêutrons , Tratamentos com Preservação do Órgão/instrumentação , Tratamentos com Preservação do Órgão/métodos , Órgãos em Risco , Terapia com Prótons/economia , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Garantia da Qualidade dos Cuidados de Saúde , Radioterapia Guiada por Imagem/tendências , SíncrotronsRESUMO
Along with surgery, radiation therapy (RT) remains an essential option to cure patients suffering from medulloblastoma. However, its long-term adverse effects, particularly due to craniospinal irradiation (CSI), which is necessary to eradicate microscopic spread, are a limiting factor. The most frequent sequelae involve neurocognitive and endocrine impairment, which occurs in nearly all patients. Recent progress achieved through genetic and molecular biology offers the possibility to better stratify patients according to risk factors such as age, post-resection tumour residue and metastasis. Thus, new therapeutic studies assess the possibility to reduce radiation dose and/or radiation field size for patients with the most favourable prognosis. New radiotherapy techniques are also used such as Intensity-Modulated Radiotherapy (IMRT), tomotherapy and proton therapy, which aim at reducing the dose delivered to normal tissue. Conventional photon-based therapy has a relatively high exit dose in contrast with proton therapy which causes less damage to surrounding healthy tissue. It is noteworthy that each technique requires a long follow-up in order to prove that late effects could be reduced without compromising survival rates. Dosimetric comparison theoretically suggests that proton therapy may be the superior method for CSI in terms of late effects, but further research is needed to firmly establish this. Whatever the technique used, the great complexity of CSI requires discipline and expertise along with an external quality control online before the first RT session.
Assuntos
Neoplasias Cerebelares/radioterapia , Radiação Cranioespinal/efeitos adversos , Meduloblastoma/radioterapia , Ototoxicidade/etiologia , Terapia com Prótons , Neoplasias Cerebelares/diagnóstico , Neoplasias Cerebelares/cirurgia , Criança , Radiação Cranioespinal/tendências , Feminino , Humanos , Masculino , Meduloblastoma/diagnóstico , Meduloblastoma/cirurgia , Ototoxicidade/diagnóstico , Prognóstico , Terapia com Prótons/tendências , Fatores de RiscoRESUMO
FLASH radiotherapy is the delivery of ultra-high dose rate radiation several orders of magnitude higher than what is currently used in conventional clinical radiotherapy, and has the potential to revolutionize the future of cancer treatment. FLASH radiotherapy induces a phenomenon known as the FLASH effect, whereby the ultra-high dose rate radiation reduces the normal tissue toxicities commonly associated with conventional radiotherapy, while still maintaining local tumor control. The underlying mechanism(s) responsible for the FLASH effect are yet to be fully elucidated, but a prominent role for oxygen tension and reactive oxygen species production is the most current valid hypothesis. The FLASH effect has been confirmed in many studies in recent years, both in vitro and in vivo, with even the first patient with T-cell cutaneous lymphoma being treated using FLASH radiotherapy. However, most of the studies into FLASH radiotherapy have used electron beams that have low tissue penetration, which presents a limitation for translation into clinical practice. A promising alternate FLASH delivery method is via proton beam therapy, as the dose can be deposited deeper within the tissue. However, studies into FLASH protons are currently sparse. This review will summarize FLASH radiotherapy research conducted to date and the current theories explaining the FLASH effect, with an emphasis on the future potential for FLASH proton beam therapy.
Assuntos
Neoplasias/radioterapia , Terapia com Prótons/métodos , Terapia com Prótons/tendências , Humanos , Prótons , Radioterapia/métodos , Radioterapia/tendências , Dosagem Radioterapêutica , Espécies Reativas de Oxigênio/metabolismoRESUMO
Proton therapy is delivered to selected cancer patients presenting with rare tumours, for which a dose escalation paradigm and/or a reduced dose-bath to the organs at risk is pursued. It is a costly treatment with an additional cost factor of 2-3 when compared to photon radiotherapy. Notwithstanding the 180'000 patients treated with protons, scars robust clinical evidence is available to justify the administration of this treatment modality. The European Particle Therapy Network (EPTN) was created in 2015 to answer the critical European needs for cooperation among protons and carbon ions centres in the framework of clinical research networks. EPTN with other European groups will launch a number of prospective clinical trials that could be practice changing if positive. Alternative way to generate clinical data could be provided by alternative methodologies, such as the Dutch model-based approach, or could be provided by European infrastructure projects.
Assuntos
Neoplasias/radioterapia , Terapia com Prótons/tendências , Pesquisa Biomédica , Europa (Continente) , Previsões , HumanosRESUMO
The effects of various forms of ionising radiation are known to be mediated by interactions with cellular and molecular targets in irradiated and in some cases non-targeted tissue volumes. Despite major advances in advanced conformal delivery techniques, the probability of normal tissue complication (NTCP) remains the major dose-limiting factor in escalating total dose delivered during treatment. Potential strategies that have shown promise as novel delivery methods in achieving effective tumour control whilst sparing organs at risk involve the modulation of critical dose delivery parameters. This has led to the development of techniques using high dose spatial fractionation (GRID) and ultra-high dose rate (FLASH) which have translated to the clinic. The current review discusses the historical development and biological basis of GRID, microbeam and FLASH radiotherapy as advanced delivery modalities that have major potential for widespread implementation in the clinic in future years.
Assuntos
Fracionamento da Dose de Radiação , Neoplasias/radioterapia , Vasos Sanguíneos/efeitos da radiação , Efeito Espectador , História do Século XX , História do Século XXI , Humanos , Neoplasias/irrigação sanguínea , Neoplasias/imunologia , Órgãos em Risco/efeitos da radiação , Fótons/uso terapêutico , Terapia com Prótons/métodos , Terapia com Prótons/tendências , Lesões por Radiação/prevenção & controle , Radiobiologia , Radioterapia/história , Radioterapia/instrumentaçãoRESUMO
Proton therapy has recently gained substantial momentum worldwide due to improved accessibility to the technology and sustained interests in its advantage of better tissue sparing compared to traditional photon radiation. Proton therapy in head and neck cancer has a unique advantage given the complex anatomy and proximity of targets to vital organs. As head and neck cancer patients are living longer due to epidemiological shifts and advances in treatment options, long-term toxicity from radiation treatment has become a major concern that may be better mitigated by proton therapy. With increased utilization of proton therapy, new proton centers breaking ground, and as excitement about the technology continue to increase, we aim to comprehensively review the evidence of proton therapy in major subsites within the head and neck, hoping to facilitate a greater understanding of the full risks and benefits of proton therapy for head and neck cancer.
Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Terapia com Prótons , Ensaios Clínicos como Assunto , Gerenciamento Clínico , Relação Dose-Resposta à Radiação , Neoplasias de Cabeça e Pescoço/diagnóstico , Neoplasias de Cabeça e Pescoço/mortalidade , Humanos , Prognóstico , Terapia com Prótons/efeitos adversos , Terapia com Prótons/métodos , Terapia com Prótons/tendências , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Resultado do TratamentoRESUMO
OBJECTIVES: Proton beam therapy (PBT) is a type of radiation therapy (RT) used for certain cancer types because it minimizes collateral tissue damage. The high cost and limited availability of PBT have constrained its utilization. This study examined patterns and determinants of PBT use in California. STUDY DESIGN: Persons with diagnoses of all cancer types from 2003 to 2016 inclusive who had any type of RT were identified in the California Cancer Registry in this retrospective analysis. METHODS: Cross-tabulations were performed to summarize the demographic characteristics of the study population, both for individuals who received PBT and for those who received other RT modalities. PBT use patterns over time were assessed. Multivariate logistic regression models assessed the effects of demographics and health insurance type on receipt of PBT. RESULTS: Of the 2,499,510 people with a cancer diagnosis during the study period, 578,632 (23%) received some type of RT, and of these, 8609 received PBT (1.5%). PBT was most often used to treat cancers of the prostate (41.3%), breast (14.0%), eye (11.7%), lung (6.1%), and brain (6.0%). PBT use was highest in 2003-2004 and then declined over time. PBT use was significantly associated with being white or male, younger age, higher socioeconomic status, Medicare or dual Medicare-Medicaid insurance, uninsured/self-pay status, and proximity to treatment. CONCLUSIONS: Significant differences exist in PBT use by demographics and health insurance type. The identified racial and socioeconomic disparities merit further investigation. More granular studies on both use patterns and effectiveness of PBT for specific cancers are needed to draw stronger conclusions about its cost-benefit ratio.
Assuntos
Neoplasias/radioterapia , Terapia com Prótons/tendências , Adulto , Idoso , California/epidemiologia , Feminino , Humanos , Cobertura do Seguro/classificação , Seguro Saúde/classificação , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Estudos Retrospectivos , Fatores SocioeconômicosRESUMO
Treatment planning is the process where the prescription of the radiation oncologist is translated into a deliverable treatment. With the complexity of contemporary radiotherapy, treatment planning cannot be performed without a computerized treatment planning system. Proton therapy (PT) enables highly conformal treatment plans with a minimum of dose to tissues outside the target volume, but to obtain the most optimal plan for the treatment, there are a multitude of parameters that need to be addressed. In this review areas of ongoing improvements and research in the field of PT treatment planning are identified and discussed. The main focus is on issues of immediate clinical and practical relevance to the PT community highlighting the needs for the near future but also in a longer perspective. We anticipate that the manual tasks performed by treatment planners in the future will involve a high degree of computational thinking, as many issues can be solved much better by e.g. scripting. More accurate and faster dose calculation algorithms are needed, automation for contouring and planning is required and practical tools to handle the variable biological efficiency in PT is urgently demanded just to mention a few of the expected improvements over the coming 10 years.
Assuntos
Algoritmos , Previsões , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Automação , Confiabilidade dos Dados , Humanos , Método de Monte Carlo , Avaliação das Necessidades , Órgãos em Risco/diagnóstico por imagem , Terapia com Prótons/tendências , Planejamento da Radioterapia Assistida por Computador/tendências , Radioterapia Conformacional/tendências , Eficiência Biológica Relativa , Fatores de TempoRESUMO
ADVANCES IN KNOWLEDGE: This review details the indication of brain tumors for proton therapy and give a list of the open prospective trials for these challenging tumors.
Assuntos
Neoplasias Encefálicas/radioterapia , Medicina Baseada em Evidências , Terapia com Prótons/métodos , Adulto , Fatores Etários , Encéfalo/efeitos da radiação , Neoplasias Encefálicas/diagnóstico por imagem , Criança , Condrossarcoma/diagnóstico por imagem , Condrossarcoma/radioterapia , Cordoma/diagnóstico por imagem , Cordoma/radioterapia , Ensaios Clínicos como Assunto , Análise Custo-Benefício , Humanos , Estudos Prospectivos , Terapia com Prótons/economia , Terapia com Prótons/tendências , Dosagem Radioterapêutica , Neoplasias da Base do Crânio/diagnóstico por imagem , Neoplasias da Base do Crânio/radioterapiaRESUMO
Radiation therapy is an essential component of treatment for locally advanced non-small cell lung cancer (NSCLC) but can be technically challenging because of the proximity of lung tumors to nearby critical organs or structures. The most effective strategy for reducing radiation-induced toxicity is to reduce unnecessary exposure of normal tissues by using advanced technology; examples from photon (X-ray) therapy have included three-dimensional conformal radiation therapy versus its predecessor, two-dimensional radiation therapy, and intensity-modulated photon radiation therapy versus its predecessor, three-dimensional conformal therapy. Using particle-beam therapy rather than photons offers the potential for further advantages because of the unique depth-dose characteristics of the particles, which can be exploited to allow still higher dose escalation to tumors with greater sparing of normal tissues, with the ultimate goal of improving local tumor control and survival while preserving quality of life by reducing treatment-related toxicity. However, the costs associated with particle therapy with protons are considerably higher than the current state of the art in photon technology, and evidence of clinical benefit from protons is increasingly being demanded to justify the higher financial burden on the healthcare system. Some such evidence is available from preclinical studies, from retrospective, single-institution clinical series, from analyses of national databases, and from single-arm prospective studies in addition to several ongoing randomized comparative trials. This review summarizes the rationale for and challenges of using proton therapy to treat thoracic cancers, reviews the current clinical experience, and suggests topics for future research.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/radioterapia , Neoplasias Pulmonares/radioterapia , Órgãos em Risco/efeitos da radiação , Terapia com Prótons/métodos , Lesões por Radiação/prevenção & controle , Radioterapia de Intensidade Modulada/métodos , Carcinoma Pulmonar de Células não Pequenas/patologia , Previsões , Humanos , Neoplasias Pulmonares/patologia , Tratamentos com Preservação do Órgão/métodos , Estudos Prospectivos , Terapia com Prótons/economia , Terapia com Prótons/tendências , Qualidade de Vida , Radioterapia Conformacional/métodos , Radioterapia de Intensidade Modulada/economia , Radioterapia de Intensidade Modulada/tendências , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Retrospectivos , Resultado do TratamentoRESUMO
Proton radiation therapy has been used clinically since 1952, and major advancements in the last 10 years have helped establish protons as a major clinical modality in the cancer-fighting arsenal. Technologies will always evolve, but enough major breakthroughs have been accomplished over the past 10 years to allow for a major revolution in proton therapy. This paper summarizes the major technology advancements with respect to beam delivery that are now ready for mass implementation in the proton therapy space and encourages vendors to bring these to market to benefit the cancer population worldwide. We state why these technologies are essential and ready for implementation, and we discuss how future systems should be designed to accommodate their required features.
Assuntos
Previsões , Marketing de Serviços de Saúde , Neoplasias/radioterapia , Posicionamento do Paciente , Terapia com Prótons/métodos , Terapia com Prótons/tendências , Radioterapia de Intensidade Modulada/métodos , Absorção de Radiação , Calibragem , Humanos , Neoplasias/diagnóstico por imagem , Movimentos dos Órgãos , Radioterapia Guiada por Imagem/métodos , Respiração , Fatores de Tempo , IncertezaRESUMO
Owing to the favorable physical and biological properties of swift ions in matter, their application to radiation therapy for highly selective cancer treatment is rapidly spreading worldwide. To date, over 90 ion therapy facilities are operational, predominantly with proton beams, and about the same amount is under construction or planning.Over the last decades, considerable developments have been achieved in accelerator technology, beam delivery and medical physics to enhance conformation of the dose delivery to complex shaped tumor volumes, with excellent sparing of surrounding normal tissue and critical organs. Nevertheless, full clinical exploitation of the ion beam advantages is still challenged, especially by uncertainties in the knowledge of the beam range in the actual patient anatomy during the fractionated course of treatment, thus calling for continued multidisciplinary research in this rapidly emerging field.This contribution will review latest developments aiming to image the patient with the same beam quality as for therapy prior to treatment, and to visualize in-vivo the treatment delivery by exploiting irradiation-induced physical emissions, with different level of maturity from proof-of-concept studies in phantoms and first in-silico studies up to clinical testing and initial clinical evaluation.
Assuntos
Neoplasias/diagnóstico por imagem , Neoplasias/radioterapia , Terapia com Prótons/tendências , Absorção de Radiação , Institutos de Câncer/estatística & dados numéricos , Institutos de Câncer/tendências , Humanos , Órgãos em Risco/efeitos da radiação , Tomografia por Emissão de Pósitrons , Terapia com Prótons/métodos , Terapia com Prótons/estatística & dados numéricos , Lesões por Radiação/prevenção & controle , Radioterapia Guiada por Imagem , IncertezaRESUMO
Charged particle therapy is the most advanced radiotherapy method in oncology. The favorable depth-dose distribution and the biological properties of charged particles have potentially a great benefit for reducing toxicity and increasing the local control. While the number of proton centers is exponentially growing worldwide, the therapy remains controversial due to the high cost and lack of level-I evidence of superior effectiveness compared to conventional X-rays. Here we will discuss the advantages and the challenges in both physics and biology to fully exploit the potential of ion therapy in medicine. The challenges include reducing the footprint and costs of accelerators, reducing range uncertainty, exploitation of the biological advantages such as the high effectiveness against hypoxic tumors, and to select patients with biology-driven personalized approaches. International collaboration in the field is likely to bring definite answers to these ongoing problems.
Assuntos
Radioterapia com Íons Pesados/métodos , Oncologia/métodos , Neoplasias/radioterapia , Terapia com Prótons/métodos , Radioterapia com Íons Pesados/tendências , Humanos , Oncologia/tendências , Fenômenos Físicos , Terapia com Prótons/tendências , Radiobiologia/tendências , Raios XRESUMO
BACKGROUND: Advances in radiation technology have transformed treatment options for patients with localized prostate cancer. The evolution of three-dimensional conformal radiation therapy and intensity-modulated radiation therapy (IMRT) have allowed physicians to spare surrounding normal organs and reduce adverse effects. The introduction of proton beam technology and its physical advantage of depositing its energy in tissue at the end-of-range maximum may potentially spare critical organs such as the bladder and rectum in prostate cancer patients. Data thus far are limited to large, observational studies that have not yet demonstrated a definite benefit of protons over conventional treatment with IMRT. The cost of proton beam treatment adds to the controversy within the field. METHODS: We performed an extensive literature review for all proton treatment-related prostate cancer studies. We discuss the history of proton beam technology, as well as its role in the treatment of prostate cancer, associated controversies, novel technology trends, a discussion of cost-effectiveness, and an overview of the ongoing modern large prospective studies that aim to resolve the debate between protons and photons for prostate cancer. RESULTS: Present data have demonstrated that proton beam therapy is safe and effective compared with the standard treatment options for prostate cancer. While dosimetric studies suggest lower whole-body radiation dose and a theoretically higher relative biological effectiveness in prostate cancer compared with photons, no studies have demonstrated a clear benefit with protons. CONCLUSIONS: Evolving trends in proton treatment delivery and proton center business models are helping to reduce costs. Introduction of existing technology into proton delivery allows further control of organ motion and addressing organs-at-risk. Finally, the much-awaited contemporary studies comparing photon with proton-based treatments, with primary endpoints of patient-reported quality-of-life, will help us understand the differences between proton and photon-based treatments for prostate cancer in the modern era.
Assuntos
Análise Custo-Benefício , Fótons/uso terapêutico , Neoplasias da Próstata/radioterapia , Terapia com Prótons/economia , Radioterapia de Intensidade Modulada/economia , Tomada de Decisão Clínica , Redução de Custos , Intervalo Livre de Doença , Medicina Baseada em Evidências/economia , Medicina Baseada em Evidências/métodos , Medicina Baseada em Evidências/tendências , Humanos , Masculino , Medidas de Resultados Relatados pelo Paciente , Fótons/efeitos adversos , Neoplasias da Próstata/economia , Neoplasias da Próstata/mortalidade , Terapia com Prótons/efeitos adversos , Terapia com Prótons/tendências , Qualidade de Vida , Radioterapia (Especialidade)/economia , Radioterapia (Especialidade)/métodos , Radioterapia (Especialidade)/tendências , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/efeitos adversos , Radioterapia de Intensidade Modulada/tendências , Taxa de Sobrevida , Resultado do TratamentoRESUMO
Imaging has an essential role in the planning and delivery of radiotherapy. Recent advances in imaging have led to the development of advanced radiotherapy techniques-including image-guided radiotherapy, intensity-modulated radiotherapy, stereotactic body radiotherapy and proton beam therapy. The optimal use of imaging might enable higher doses of radiation to be delivered to the tumour, while sparing normal surrounding tissues. In this article, we review how the integration of existing and novel forms of computed tomography, magnetic resonance imaging and positron emission tomography have transformed tumour delineation in the radiotherapy planning process, and how these advances have the potential to allow a more individualised approach to the cancer therapy. Recent data suggest that imaging biomarkers that assess underlying tumour heterogeneity can identify areas within a tumour that are at higher risk of radio-resistance, and therefore potentially allow for biologically focussed dose escalation. The rapidly evolving concept of adaptive radiotherapy, including artificial intelligence, requires imaging during treatment to be used to modify radiotherapy on a daily basis. These advances have the potential to improve clinical outcomes and reduce radiation-related long-term toxicities. We outline how recent technological advances in both imaging and radiotherapy delivery can be combined to shape the future of precision radiation oncology.
Assuntos
Neoplasias/diagnóstico por imagem , Neoplasias/radioterapia , Radioterapia (Especialidade)/tendências , Humanos , Imageamento por Ressonância Magnética/métodos , Neoplasias/patologia , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Terapia com Prótons/tendências , Radiocirurgia/tendências , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/tendências , Radioterapia de Intensidade Modulada/tendênciasRESUMO
Proton radiotherapy is undergoing rapid expansion both within the UK and internationally, but significant challenges still need to be overcome if maximum benefit is to be realised from this technique. One major limitation is the persistent uncertainty in proton relative biological effectiveness (RBE). While RBE values are needed to link proton radiotherapy to our existing experience with photon radiotherapy, RBE remains poorly understood and is typically incorporated as a constant dose scaling factor of 1.1 in clinical plans. This is in contrast to extensive experimental evidence indicating that RBE is a function of dose, tissue type, and proton linear energy transfer, among other parameters. In this article, we discuss the challenges associated with obtaining clinically relevant values for proton RBE through commonly-used assays, and highlight the wide range of other experimental end points which can inform our understanding of RBE. We propose that accurate and robust optimization of proton radiotherapy ultimately requires a multiscale understanding of RBE, integrating subcellular, cellular, and patient-level processes.
Assuntos
Neoplasias/radioterapia , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Eficiência Biológica Relativa , Animais , Relação Dose-Resposta à Radiação , Previsões , Humanos , Método de Monte Carlo , Avaliação das Necessidades , Neoplasias/patologia , Segurança do Paciente/estatística & dados numéricos , Terapia com Prótons/tendências , Ensaios Clínicos Controlados Aleatórios como Assunto , Medição de Risco , Resultado do TratamentoRESUMO
PURPOSE: To evaluate the feasibility of image-guided adaptive proton therapy (IGAPT) with a mobile helical-CT without rails. METHOD: CT images were acquired with a 32-slice mobile CT (mCT) scanning through a 6 degree-of-freedom robotic couch rotated isocentrically 90 degrees from an initial setup position. The relationship between the treatment isocenter and the mCT imaging isocenter was established by a stereotactic reference frame attached to the treatment couch. Imaging quality, geometric integrity and localization accuracy were evaluated according to AAPM TG-66. Accuracy of relative stopping power ratio (RSPR) was evaluated by comparing water equivalent distance (WED) and dose calculations on anthropomorphic phantoms to that of planning CT (pCT). Feasibility of image-guided adaptive proton therapy was demonstrated on fractional images acquired with the mCT scanner. RESULTS: mCT images showed slightly lower spatial resolution and a higher contrast-to-noise ratio compared to pCT images from the standard helical CT scanner. The geometric accuracy of the mCT was <1â¯mm. Localization accuracy was <0.4â¯mm and <0.3° with respect to 2DkV/kV matching. WED differences between mCT and pCT images were negligible, with discrepancies of 0.8⯱â¯0.6â¯mm and 1.3⯱â¯0.9â¯mm for brain and lung phantoms respectively. 3D gamma analysis (3% and 3â¯mm) passing rate was >95% on dose computed on mCT, with respect to dose calculation on pCT. CONCLUSION: Our study has demonstrated that the geometric integrity, image quality and RSPR accuracy of the mCT are sufficient for IGAPT.
Assuntos
Terapia com Prótons/instrumentação , Tomografia Computadorizada Espiral/instrumentação , Desenho de Equipamento , Estudos de Viabilidade , Humanos , Imagens de Fantasmas , Sistemas Automatizados de Assistência Junto ao Leito/tendências , Terapia com Prótons/métodos , Terapia com Prótons/tendências , Prótons , Tomógrafos Computadorizados , Tomografia Computadorizada Espiral/tendênciasRESUMO
BACKGROUND: Propofol is an excellent hypnotic drug for use in repeated radiation procedures in young children. To date, tolerance to propofol generally does not develop in pediatric patients undergoing radiation therapy. However, several studies have suggested that there may be potential for development of tolerance to propofol. The aim of this study was to evaluate the development of a tolerance to propofol used for repeated deep sedation in children undergoing proton radiation therapy (PRT). METHODS: All children undergoing PRT at our institution between December 2015 and January 2018 were eligible for inclusion in this study. Sedation was induced by a bolus dose of propofol (2.0 mg.kg- 1) followed by a continuous infusion of 250 µg.kg- 1.min- 1 via an infusion pump to achieve deep sedation. Sedation was maintained with the propofol infusion of 200 µg.kg- 1.min- 1, which was adjusted in 25 µg.kg- 1.min- 1 increments up or down as necessary to ensure deep sedation. The primary outcome was mean doses of propofol over time. RESULTS: Fifty-eight children were analyzed. The mean (SD) age was 4.5 (2.1) years. The mean (SD) number of treatment sessions was 19 (7). Fifteen patients (26%) developed tolerance to propofol. However, there were no significant differences between the children who developed tolerance and the children who did not develop tolerance in mean propofol dose and awakening time over time (p = 0.887 and P = 0.652, respectively). Age, the number of PRT, and attending anesthesiologists was not significantly associated with the incidence of tolerance to propofol. CONCLUSION: Repeated prolonged deep sedation for PRT elicited multiple times over several weeks in young children using propofol did not develop tolerance in 74% of patients. Although the incidence of 26% tolerance to propofol may still be present, the increase in propofol dose was minimal. Therefore, the use of repeated propofol for children was safe.
Assuntos
Tolerância a Medicamentos/fisiologia , Hipnóticos e Sedativos/administração & dosagem , Propofol/administração & dosagem , Terapia com Prótons/métodos , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/radioterapia , Criança , Pré-Escolar , Esquema de Medicação , Feminino , Humanos , Incidência , Infusões Intravenosas , Masculino , Terapia com Prótons/tendências , Estudos RetrospectivosRESUMO
Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death, as few patients can be treated with currently available curative local modalities. In patients with HCC where curative modalities are not feasible, radiation therapy (RT) has emerged as an alternative or combination therapy. With the development of various technologies, RT has been increasingly used for the management of HCC. Among these advances, proton beam therapy (PBT) has several unique physical properties that give it a finite range in a distal direction, and thus no exit dose along the beam path. Therefore, PBT has dosimetric advantages compared with X-ray therapy for the treatment of HCC. Indeed, various reports in the literature have described the favorable clinical outcomes and improved safety of PBT for HCC patients compared with X-ray therapy. However, there are some technical issues regarding the use of PBT in HCC, including uncertainty of organ motion and inaccuracy during calculation of tissue density and beam range, all of which may reduce the robustness of a PBT treatment plan. In this review, we discuss the physical properties, current clinical data, technical issues, and future perspectives on PBT for the treatment of HCC.