Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.024
Filtrar
1.
Int J Radiat Oncol Biol Phys ; 106(2): 413-421, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31655198

RESUMO

PURPOSE: The transition from frame-based brain stereotactic radiosurgery (SRS) to frameless delivery is supported by real-time intrafraction monitoring to ensure accurate delivery. The purpose of this study is to characterize these real-time motion traces in a large cohort of patients treated with frameless gated brain SRS and to develop patient-specific predictions of tolerance violations. METHODS AND MATERIALS: SRS patients treated on the Gamma Knife Icon were immobilized using a device-specific thermoplastic head mask. A motion marker was fixed to the patient's nose, with gating and cone beam computed tomography (CBCT)-based corrections to the treatment at excursions from baseline exceeding 1.5 mm. The traces of 1446 fractions were analyzed according to magnitude (932 unique treatment plans for 462 unique individual patients), directional distribution of displacement, and stability. A neural network model was developed to predict interruptions based on a subset of trace data. RESULTS: The average displacement of the marker in the first fraction of all patients was 0.62 ± 0.25 mm with beam CBCT corrections, which would otherwise be modeled at 0.96 ± 0.96 mm without intrafraction motion correction (P < .0001). Twenty-nine percent of fractions delivered were interrupted, of which the Z-axis (superoinferior) motion was the largest contributor to excursion. Baseline corrections significantly compensated for the magnitude of motion in all 3 dimensions (P < .01). The motion relative to the first acquired CBCT was on average seen to consistently increase with treatment time, with the minimum P value occurring at 61.3 minutes. The neural network prediction model was able to predict treatment interruptions with 84% sensitivity on the first 5-minute sample of the trace. CONCLUSIONS: Corrections to marker position significantly decreased marker excursions in all 3 axes compared with a single CBCT alignment. Patient-specific modeling may aid in the optimization of cases selected for frameless radiosurgery to increase the accuracy of planned delivery.


Assuntos
Neoplasias Encefálicas/radioterapia , Sistemas de Computação , Movimentos dos Órgãos , Radiocirurgia/métodos , Radioterapia Guiada por Imagem/métodos , Neoplasias Encefálicas/diagnóstico por imagem , Tomografia Computadorizada de Feixe Cônico , Marcadores Fiduciais , Humanos , Imobilização/instrumentação , Raios Infravermelhos , Máscaras , Nariz , Radiocirurgia/instrumentação
2.
Int J Radiat Oncol Biol Phys ; 106(1): 116-123, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31604131

RESUMO

PURPOSE: The aim of this analysis was to assess the 5-year tolerance and survival in patients undergoing hypofractionated stereotactic boost after external beam radiation therapy (EBRT) for intermediate-risk prostate cancer. METHODS AND MATERIALS: Between August 2010 and April 2013, 76 patients with intermediate-risk prostate carcinoma were included in the study. A first course delivered 46 Gy using conventional fractionation. The second course delivered a boost of 18 Gy (3 × 6 Gy) within 10 days using stereotactic body radiation therapy (SBRT). Gastrointestinal and genitourinary toxicities were assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events v4.0. Secondary outcome measures were overall, biochemical relapse-free, and relapse-free survival; prostate-specific antigen kinetics; and patient functional status (urinary and sexual) according to the International Index of Erectile Function and International Prostate Symptom Score questionnaires. RESULTS: Sixty patients (79%) were treated by CyberKnife and 16 (21%) by linear accelerator. Median follow-up was 62 months (range, 29-69). The cumulative incidence of genitourinary and gastrointestinal grade ≥2 toxicities at month 60 after the end of radiation therapy was 1.4% (95% confidence interval [CI], 0.1%-6.6%) and 9.3% (95% CI, 4.1%-17.1%), respectively. Biochemical relapse-free and relapse-free survival rates at 5 years were 87.4% (95% CI, 77.1%-93.2%) and 86.2% (95% CI, 75.8-92.3), respectively. The mean (standard deviation) prostate-specific antigen variation within 3 months and 5 years post-radiation therapy was -1.20 ng/mL/mo (0.79) and -1.30 ng/mL/y (1.05), respectively. There was no significant difference between the International Prostate Symptom quality of life score between inclusion and month 60. For the International Index of Erectile Function, there was a significant difference between inclusion and month 60 (P = .005), with a higher proportion of severe/noninterpretable disorders at 60 months. CONCLUSIONS: The results of the trial demonstrate that the EBRT and SBRT combination is well tolerated and yields good efficacy results. These data provide a good basis for comparing EBRT and brachytherapy boost to EBRT and SBRT boost in future prospective studies.


Assuntos
Neoplasias da Próstata/radioterapia , Radiocirurgia/métodos , Reirradiação/métodos , Idoso , Idoso de 80 Anos ou mais , Disfunção Erétil/epidemiologia , Marcadores Fiduciais , Humanos , Masculino , Pessoa de Meia-Idade , Órgãos em Risco/efeitos da radiação , Prevalência , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/sangue , Neoplasias da Próstata/mortalidade , Hipofracionamento da Dose de Radiação , Radiocirurgia/efeitos adversos , Radiocirurgia/instrumentação , Radiocirurgia/mortalidade , Reirradiação/efeitos adversos , Reto/efeitos da radiação , Fatores de Tempo , Resultado do Tratamento , Bexiga Urinária/efeitos da radiação , Transtornos Urinários/epidemiologia
3.
Ideggyogy Sz ; 72(11-12): 427-431, 2019 Nov 30.
Artigo em Húngaro | MEDLINE | ID: mdl-31834687

RESUMO

Among tumours found in the suprasellar region metastases are very rare and the most frequent primary tumours are lung and breast cancer. Data of a patient with clear cell renal carcinoma with intra-suprasellar metastasis will be discussed. As in most of the tumours in the sellar region, the first symptom was visual deterioration with visual field defect. A transsphenoidal debulking of the tumour was performed and the residual tumor was treated by CyberKnife hypofractionated stereotactic radiotherapy. Both our patient's visual acuity and visual field impairment improved after the surgery and CyberKnife treatment. At 6-month after irradiation, MR of the sella showed a complete remission of the tumour. This was the first treatment with CyberKnife in our country in case of a tumour close to the optic chiasm. According to our best knowledge, there are 21 cases in the literature with renal cell carcinoma metastasis in the suprasellar region.


Assuntos
Carcinoma de Células Renais/cirurgia , Neoplasias Renais/cirurgia , Nervo Óptico/cirurgia , Radiocirurgia/métodos , Sela Túrcica/cirurgia , Carcinoma de Células Renais/patologia , Humanos , Neoplasias Renais/patologia , Metástase Neoplásica , Nervo Óptico/patologia , Neoplasias Hipofisárias , Radiocirurgia/instrumentação , Resultado do Tratamento , Transtornos da Visão/etiologia
4.
World Neurosurg ; 130: 593-607, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31581409

RESUMO

Stereotactic radiosurgery is a modern discipline that emerged after World War II. It represents a synthesis of an approach to patient care that was not immediately embraced by either neurosurgeons or radiation oncologists, but which has been shown, time and again, to be advantageous for the treatment of intracranial pathology. Indeed, stereotactic radiosurgical techniques are now being rapidly adapted and adopted for the treatment of extracranial malignant and benign disease. Any examination of the individuals, devices, and technological advances that permitted stereotactic radiosurgery to become a preferred approach for patient care cannot be absolutely comprehensive but can provide insights into the evolution of the specialty and potential future prospects for further improvements in patient care. As Shakespeare wrote in The Tempest, "What's past is prologue."


Assuntos
Neurocirurgia/história , Radiocirurgia/história , História do Século XX , Humanos , Neuronavegação/história , Neuronavegação/instrumentação , Neurocirurgia/instrumentação , Radiocirurgia/instrumentação
5.
Phys Med ; 64: 204-209, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31515021

RESUMO

PURPOSE: We evaluated the feasibility of electronic portal imaging based 3D in-vivo dosimetry for stereotactic body radiation therapy (SBRT) technique in prostate cancer. METHODS AND MATERIALS: To investigate error detectability limitations of iViewDose™ v.1.0.1 (Elekta, Stockholm, Sweden) for prostate SBRT cases, ten prostate cancer patients were selected and in-vivo electronic portal imaging devices dosimetry was performed. Also possible error scenarios including dose calibration, setup, collimator, multi leaf collimator and patient anatomy related inaccuracies were created to investigate detectability of EPID. For this purpose, a SBRT treatment was planned on BrainLab pelvis phantom (BrainLab Medical Systems, Westchester, IL) and irradiated after proving setup with cone beam computer tomography. After that incorrect plans were irradiated and obtained results were compared with original in vivo measurements. RESULTS: Mean gamma analysis (γ% ≤ 1) passing rate of ten patients was found as 96.2%. Additionally, mean dose reference point difference between measurement and calculated in treatment planning system for clinical target volume, rectum, bladder, left and right femur heads were found as 1.4%, 8%, 20.8%, 2.3% and 4.5%, respectively. Phantom measurements showed that positional errors can be escape from detection. However, the incorrect treated plans including linac calibration, MLC positions and patient anatomy based errors could not have passed the in vivo dosimetry analysis. CONCLUSIONS: EPID-based 3D in vivo dosimetry software (iViewDose) provides an efficient safety check on the accuracy of dose delivery during prostate SBRT treatments. However, phantom results showed some limitation of the system.


Assuntos
Equipamentos e Provisões Elétricas , Neoplasias da Próstata/radioterapia , Radiocirurgia/instrumentação , Radioterapia Guiada por Imagem/instrumentação , Estudos de Viabilidade , Humanos , Masculino , Aceleradores de Partículas , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
6.
Radiat Oncol ; 14(1): 172, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31533746

RESUMO

BACKGROUND: Vendor-independent Monte Carlo (MC) dose calculation (IDC) for patient-specific quality assurance of multi-leaf collimator (MLC) based CyberKnife treatments is used to benchmark and validate the commercial MC dose calculation engine for MLC based treatments built into the CyberKnife treatment planning system (Precision MC). METHODS: The benchmark included dose profiles in water in 15 mm depth and depth dose curves of rectangular MLC shaped fields ranging from 7.6 mm × 7.7 mm to 115.0 mm × 100.1 mm, which were compared between IDC, Precision MC and measurements in terms of dose difference and distance to agreement. Dose distributions of three phantom cases and seven clinical lung cases were calculated using both IDC and Precision MC. The lung PTVs ranged from 14 cm3 to 93 cm3. Quantitative comparison of these dose distributions was performed using dose-volume parameters and 3D gamma analysis with 2% global dose difference and 1 mm distance criteria and a global 10% dose threshold. Time to calculate dose distributions was recorded and efficiency was assessed. RESULTS: Absolute dose profiles in 15 mm depth in water showed agreement between Precision MC and IDC within 3.1% or 1 mm. Depth dose curves agreed within 2.3% / 1 mm. For the phantom and clinical lung cases, mean PTV doses differed from - 1.0 to + 2.3% between IDC and Precision MC and gamma passing rates were > =98.1% for all multiple beam treatment plans. For the lung cases, lung V20 agreed within ±1.5%. Calculation times ranged from 2.2 min (for 39 cm3 PTV at 1.0 × 1.0 × 2.5 mm3 native CT resolution) to 8.1 min (93 cm3 at 1.1 × 1.1 × 1.0 mm3), at 2% uncertainty for Precision MC for the 7 examined lung cases and 4-6 h for IDC, which, however, is not optimized for efficiency but used as a gold standard for accuracy. CONCLUSIONS: Both accuracy and efficiency of Precision MC in the context of MLC based planning for the CyberKnife M6 system were benchmarked against MC based IDC framework. Precision MC is used in clinical practice at our institute.


Assuntos
Algoritmos , Neoplasias Pulmonares/cirurgia , Método de Monte Carlo , Imagens de Fantasmas , Neoplasias da Próstata/cirurgia , Radiocirurgia/instrumentação , Radiocirurgia/métodos , Benchmarking , Humanos , Neoplasias Pulmonares/patologia , Masculino , Órgãos em Risco/efeitos da radiação , Prognóstico , Neoplasias da Próstata/patologia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos
7.
J Appl Clin Med Phys ; 20(9): 143-148, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31538717

RESUMO

PURPOSE: To evaluate a scintillator detector for patient-specific quality assurance of VMAT radiosurgery plans. METHODS: The detector was comprised of a 1 mm diameter, 1 mm high scintillator coupled to an acrylic optical fiber. Sixty VMAT SRS plans for treatment of single targets having sizes ranging from 3 mm to 30.2 mm equivalent diameter (median 16.3 mm) were selected. The plans were delivered to a 20 cm × 20 cm x 15 cm water equivalent plastic phantom having either the scintillator detector or radiochromic film at the center. Calibration films were obtained for each measurement session. The films were scanned and converted to dose using a 3-channel technique. RESULTS: The mean difference between scintillator and film was -0.45% (95% confidence interval -0.1% to 0.8%). For target equivalent diameter smaller than the median, the mean difference was 1.1% (95% confidence interval 0.5% to 1.7%). For targets larger than the median, the mean difference was -0.2% (95% confidence interval -0.7% to 0.1%). CONCLUSIONS: The scintillator detector response is independent of target size for targets as small as 3 mm and is well-suited for patient-specific quality assurance of VMAT SRS plans. Further work is needed to evaluate the accuracy for VMAT plans that treat multiple targets using a single isocenter.


Assuntos
Imagens de Fantasmas , Plásticos , Garantia da Qualidade dos Cuidados de Saúde/normas , Radiocirurgia/instrumentação , Radiocirurgia/normas , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Contagem de Cintilação/instrumentação , Calibragem , Humanos , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica
8.
Cancer Radiother ; 23(6-7): 658-661, 2019 Oct.
Artigo em Francês | MEDLINE | ID: mdl-31471252

RESUMO

Stereotactic radiotherapy represents a fundamental change in the practice of radiotherapy of lung cancers. Despite the great heterogeneity of sites, techniques, and doses, most studies found a high local control rate, around 70 to 90% at 2 years, and reduced toxicity, around 5% of grade 3 at 2 years. Stereotactic radiotherapy can be realized either by a dedicated accelerator (CyberKnife®) or by a conventional accelerator associated with specific systems. The two modalities deliver a very precise irradiation whose very good results published to date are similar. Some technical characteristics specific to each type of linear accelerator could guide the choice according to the target volume treated.


Assuntos
Neoplasias Pulmonares/radioterapia , Aceleradores de Partículas , Radiocirurgia/instrumentação , Humanos , Movimentos dos Órgãos , Órgãos em Risco/efeitos da radiação , Radiocirurgia/métodos , Respiração , Resultado do Tratamento
9.
Vet Clin North Am Exot Anim Pract ; 22(3): 471-487, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31395326

RESUMO

Surgery can be challenging in exotic pets owing to their small size and blood volume, and their increased anesthetic risk compared with small animals. Various devices are available to facilitate suturing, cutting, and hemostasis in the human and veterinary fields. These surgical equipment improve the simplicity, rapidity, and effectiveness of surgery. Vessel-sealing devices, radiosurgery, lasers, and ultrasound devices are commonly used because of their ease of use and increase in surgical efficiency. Other surgical devices are available (eg, stapling devices) but are not discussed in this article.


Assuntos
Animais Exóticos , Equipamentos Cirúrgicos/veterinária , Animais , Biópsia/instrumentação , Biópsia/veterinária , Castração/instrumentação , Castração/veterinária , Desenho de Equipamento , Hemostasia Cirúrgica/instrumentação , Hemostasia Cirúrgica/veterinária , Humanos , Terapia a Laser/instrumentação , Terapia a Laser/veterinária , Lasers/normas , Fígado/patologia , Fígado/cirurgia , Pancreatectomia/instrumentação , Pancreatectomia/veterinária , Radiocirurgia/instrumentação , Radiocirurgia/veterinária , Esplenectomia/instrumentação , Esplenectomia/veterinária , Equipamentos Cirúrgicos/tendências , Procedimentos Cirúrgicos Ultrassônicos/instrumentação , Procedimentos Cirúrgicos Ultrassônicos/veterinária , Procedimentos Cirúrgicos Vasculares/instrumentação
10.
World Neurosurg ; 132: e680-e686, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31442651

RESUMO

BACKGROUND: To assess the neuroimaging and clinical outcomes in patients with brainstem metastasis (BSM) treated with linac-based fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator. METHODS: Between May 2007 and January 2017, 24 patients (15 male and 9 female) with BSM (25 lesions: midbrain, 10; pons, 13; and medulla oblongata, 2) were consecutively treated with linac-based fSRT. BSM originated from the lung (n = 18, 75.0%), colon (n = 3, 12.5%), and breast (n = 3, 12.5%). The median patient age was 67.0 (range: 42-80) years. Recursive partition analysis classified 2 patients as class I, 17 as class II, and 5 as class III. Overall survival was calculated using the Kaplan-Meier method. RESULTS: Tumor volume ranged from 0.01 to 7.49 cm3 (median: 0.233 cm3), and patients were treated with a dose of 24-40 Gy in 7-13 fractions. The median OS was 9 months after fSRT (95% confidence interval 4.104-13.896). Large tumor volume, presence of brainstem-related symptoms, poor pretreatment Karnofsky performance status, and recursive partition analysis class III were significantly associated with low overall survival. Tumor volume decreased in 18 metastatic lesions, remained stable in 6, and increased in 1. No patient exhibited permanent radiation injury. Grade 2 nausea and vomiting according to the Common Terminology Criteria for Adverse Events 4.0 occurred in 1 patient who received corticosteroids. CONCLUSIONS: Linac-based fSRT with a micro-multileaf collimator delivered in the doses of 24-40 Gy in 7-13 fractions is a safe and effective local therapy for patients with BSM.


Assuntos
Neoplasias do Tronco Encefálico/secundário , Neoplasias do Tronco Encefálico/cirurgia , Radiocirurgia/instrumentação , Radiocirurgia/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Estimativa de Kaplan-Meier , Avaliação de Estado de Karnofsky , Masculino , Pessoa de Meia-Idade , Aceleradores de Partículas , Complicações Pós-Operatórias/epidemiologia , Náusea e Vômito Pós-Operatórios/epidemiologia , Doses de Radiação , Radiocirurgia/efeitos adversos , Estudos Retrospectivos , Análise de Sobrevida , Resultado do Tratamento
11.
Phys Med ; 65: 40-45, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31430585

RESUMO

PURPOSE: The aims of this study were: (i) to validate in a multi-site context the suitability of the IBA Razor silicon diode detector for CyberKnife relative dosimetry. (ii) to fit the multi-center experimental data into a function relating the field output factors to the effective field size (EFS). METHODS AND MATERIALS: Ratio of detector readings in clinical and reference field (OFdet) and beam profiles were acquired on five CyberKnife units for fixed collimator diameters (range 5-60 mm), using both Razor and PTW 60017 diodes. Measured OFdet were corrected using published MonteCarlo correction factors to get field output factors ΩQclin,Qmsrfclin,fmsr. Profiles were analyzed in terms of penumbra and EFS. ΩQclin,Qmsrfclin,fmsr obtained in four centers were fitted as a function of EFS, while the data of the 5th center were used to validate the fitting curve. RESULTS: Differences between Razor and PTW60017 ΩQclin,Qmsrfclin,fmsr were within 1.5% over all centers down to 7.5 mm aperture and within 3.5% for the 5 mm diameter. The fit showed a coefficient of determination R2 = 0.997. The mean deviation of measured points from the predictive curve was within 0.5%. Data of the 5th center showed a mean deviation of 0.4% from the curve, with maximum differences within 2.5% for the 7.5 mm aperture. CONCLUSIONS: The results confirmed the suitability of Razor detector for CyberKnife dosimetry by comparison to the PTW 60017 diode which has been well characterized and is in widespread use. The proposed mathematical relation between ΩQclin,Qmsrfclin,fmsr and EFS is a robust predictive model applicable to different CyberKnife systems and detectors.


Assuntos
Equipamentos e Provisões Elétricas , Radiometria/instrumentação , Radiocirurgia/instrumentação , Animais , Aceleradores de Partículas , Silício
12.
Cancer Radiother ; 23(6-7): 523-525, 2019 Oct.
Artigo em Francês | MEDLINE | ID: mdl-31444077

RESUMO

The Centre Finistérien de radiothérapie et d'oncologie, based in Brest (France), wanted to expand its activity by offering intracranial stereotactic radiation therapy to improve patient care. The desire of the Centre was to invest in this innovative and efficient technique and thus modernize its technical platform and its offer of care. The introduction of intracranial stereotactic radiation therapy requires vigilance for the technical and human organization. Therefore, the Centre prepared the implementation of this technique upstream by a structured and timed preliminary project management.


Assuntos
Institutos de Câncer , Consenso , Irradiação Craniana/métodos , Implementação de Plano de Saúde , Radiocirurgia/métodos , Irradiação Craniana/instrumentação , França , Humanos , Educação de Pacientes como Assunto , Projetos Piloto , Radiocirurgia/educação , Radiocirurgia/instrumentação , Medição de Risco
13.
Cancer Radiother ; 23(6-7): 636-650, 2019 Oct.
Artigo em Francês | MEDLINE | ID: mdl-31444078

RESUMO

Liver stereotactic body radiotherapy is a developing technique for the treatment of primary tumours and metastases. Its implementation is complex because of the particularities of the treated organ and the comorbidities of the patients. However, this technique is a treatment opportunity for patients otherwise in therapeutic impasse. The scientific evidence of liver stereotactic body radiotherapy has been considered by the French health authority as insufficient for its widespread use outside specialized and experienced centers, despite a growing and important number of retrospective and prospective studies, but few comparative data. This article focuses on the specific features of stereotactic body radiotherapy for liver treatments and the results of published studies of liver stereotactic body radiotherapy performed with classic linear accelerators and dedicated radiosurgery units.


Assuntos
Carcinoma Hepatocelular/radioterapia , Neoplasias Hepáticas/radioterapia , Radiocirurgia/instrumentação , Carcinoma Hepatocelular/diagnóstico por imagem , Humanos , Fígado/efeitos da radiação , Cirrose Hepática/complicações , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/secundário , Movimentos dos Órgãos , Aceleradores de Partículas , Guias de Prática Clínica como Assunto , Tolerância a Radiação , Radiocirurgia/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/métodos , Respiração , Resultado do Tratamento
14.
Cancer Radiother ; 23(6-7): 651-657, 2019 Oct.
Artigo em Francês | MEDLINE | ID: mdl-31447340

RESUMO

For the last decade, stereotactic body radiotherapy has become a leading treatment for localized prostate cancer. It can be delivered using a wide array of radiotherapy machines. However, although numerous clinical studies, both prospective and retrospective, have been published, the different techniques have never been properly compared. This article aims at giving an overview of the published trials, and at pointing out the major differences between the machines, from a clinical (efficacy end toxicity), technical and radiobiological point of view.


Assuntos
Aceleradores de Partículas , Neoplasias da Próstata/radioterapia , Radiocirurgia/instrumentação , Ensaios Clínicos como Assunto , Fracionamento da Dose de Radiação , Humanos , Masculino , Estudos Prospectivos , Radiocirurgia/efeitos adversos , Radiocirurgia/métodos , Radioterapia Conformacional/métodos , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Fatores de Tempo
15.
Cancer Radiother ; 23(6-7): 625-629, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31447346

RESUMO

Recent technological developments in linear accelerators (linacs) and their imaging systems have made it possible to routinely perform stereotactic radiotherapy (SRT) treatments. To ensure the security and quality of the treatments, national and international recommendations have been written. This review focuses on the recommendations of the report 91 of the International Commission on Radiation Units (ICRU) on stereotactic treatments with small photon beams and proposes to answer the question of the eligibility of the commercially available accelerators for the treatment of extra-cranial SRT (SBRT). The ICRU 91 report outlines important features needed to respect the constraints, which are high intensity photon beam, integrated image-guidance, high mechanical accuracy of the linac, multileaf collimator with reduced leaf width, bundled motion management and bundled 6 Dimensional "robotic" couch tabletop. Most of the contemporary linacs meet these recommendations, in particular, stereotactic dedicated linacs, or modern gantry-based linacs equipped with 3 dimensional cone-beam CT imaging and 2D-stereoscopic planar imaging. Commercially available ring-based linacs have some limitations: they offer only coplanar treatments, and couch movements are limited to translations and, some have limited imaging equipment and no ability to manage intrafraction motion. However, for performing SBRT, non-coplanar irradiations are not mandatory, contrarily to intracranial stereotactic irradiations. Furthermore, patients' rotations can be corrected, thanks to real-time adaptive radiotherapy available on MRI-linacs. Finally, significant improvements are expected in the short term to compensate the weaknesses of the current devices.


Assuntos
Fidelidade a Diretrizes , Agências Internacionais/normas , Neoplasias/radioterapia , Aceleradores de Partículas/normas , Radiocirurgia/instrumentação , Desenho de Equipamento/normas , Humanos , Imobilização/instrumentação , Fótons/uso terapêutico , Garantia da Qualidade dos Cuidados de Saúde , Radiocirurgia/métodos , Radiocirurgia/normas , Radioterapia Guiada por Imagem/normas
16.
J Appl Clin Med Phys ; 20(9): 12-19, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31282083

RESUMO

PURPOSE: Increased use of Linac-based stereotactic radiosurgery (SRS), which requires highly noncoplanar gantry trajectories, necessitates the development of efficient and accurate methods of collision detection during the treatment planning process. This work outlines the development and clinical implementation of a patient-specific computed tomography (CT) contour-based solution that utilizes Eclipse Scripting to ensure maximum integration with clinical workflow. METHODS: The collision detection application uses triangle mesh structures of the gantry and couch, in addition to the body contour of the patient taken during CT simulation, to virtually simulate patient treatments. Collision detection is performed using Binary Tree Hierarchy detection methods. Algorithm accuracy was first validated for simple cuboidal geometry using a calibration phantom and then extended to an anthropomorphic phantom simulation by comparing the measured minimum distance between structures to the predicted minimum distance for all allowable orientations. The collision space was tested at couch angles every 15° from 90 to 270 with the gantry incremented by 5° through the maximum trajectory. Receiver operating characteristic curve analysis was used to assess algorithm sensitivity and accuracy for predicting collision events. Following extensive validation, the application was implemented clinically for all SRS patients. RESULTS: The application was able to predict minimum distances between structures to within 3 cm. A safety margin of 1.5 cm was sufficient to achieve 100% sensitivity for all test cases. Accuracy obtained was 94.2% with the 5 cm clinical safety margin with 100% true positive collision detection. A total of 88 noncoplanar SRS patients have been currently tested using the application with one collision detected and no undetected collisions occurring. The average time for collision testing per patient was 2 min 58 s. CONCLUSIONS: A collision detection application utilizing patient CT contours was developed and successfully clinically implemented. This application allows collisions to be detected early during the planning process, avoiding patient delays and unnecessary resource utilization if detected during delivery.


Assuntos
Erros Médicos/prevenção & controle , Neoplasias/cirurgia , Imagens de Fantasmas , Radiocirurgia/instrumentação , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Software , Algoritmos , Humanos , Posicionamento do Paciente , Reconhecimento Automatizado de Padrão , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos
17.
J Appl Clin Med Phys ; 20(6): 91-98, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31095866

RESUMO

PURPOSE: To evaluate the accuracy of monitoring intrafraction motion during stereotactic radiotherapy with the optical surface monitoring system. Prior studies showing a false increase in the magnitude of translational offsets at non-coplanar couch positions prompted the vendor to implement software changes. This study evaluated two software improvements intended to address false offsets. METHODS: The vendor implemented two software improvements: a volumetric (ACO) rather than planar calibration and, approximately 6 months later, an improved calibration workflow (CIB) designed to better compensate for thermal drift. Offsets relative to the reference position, obtained at table angle 0 following image-guided setup, were recorded before beam-on at each table position and at the end of treatment the table returned to 0° for patients receiving SRT. RESULTS: Prior to ACO, between ACO and CIB, and after CIB, 223, 155, and 436 fractions were observed respectively. The median magnitude of translational offsets at the end of treatment was similar for all three intervals: 0.29, 0.33, and 0.27 mm. Prior to ACO, the offset magnitude for non-zero table positions had a median of 0.79 mm and was found to increase with increasing distance from isocenter to the anterior patient surface. After ACO, the median magnitude was 0.74 mm, but the dependence on surface-to-isocenter distance was eliminated. After CIB, the median magnitude for non-zero table positions was reduced to 0.57 mm. CONCLUSION: Ongoing improvements in software and calibration procedures have decreased reporting of false offsets at non-zero table angles. However, the median magnitude for non-zero table angles is larger than that observed at the end of treatment, indicating that accuracy remains better when the table is not rotated.


Assuntos
Neoplasias Encefálicas/cirurgia , Posicionamento do Paciente , Imagens de Fantasmas , Radiocirurgia/instrumentação , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Cirurgia Assistida por Computador/instrumentação , Neoplasias Encefálicas/patologia , Humanos , Imobilização , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Software
18.
Prog Neurol Surg ; 34: 19-27, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31096212

RESUMO

For more than 65 years localization of brain targets suitable for stereotactic radiosurgery has been performed after application of an intracranial guiding device to the cranial vault. After imaging and dose planning the same frame is used to secure the target at the focus of the intersection of the ionizing radiation beams that create the radiobiological effect. Non-invasive immobilization systems first proposed for linear accelerator or proton radiation technologies have now been developed for the Leksell Gamma Knife ICON radiosurgical system. The ICON technology adds a cone-beam computed tomography (CBCT) scan to the original Perfexion radiosurgical device in order to define the brain stereotactic space. Marketed since 2015, the ICON can be used for standard radiosurgical procedures, most of which remain frame based, but also coupled with a non-invasive thermoplastic mask for carefully selected patients who undergo standard single-session radiosurgical procedures, as well as multisession procedures using repeat mask fixation. Both at UPMC as well as worldwide, mask immobilization has to date been used for approximately 10% of patients with specific characteristics: relatively simple dose plans, short radiation delivery times, and non-anxious patients, most of whom have metastatic or primary brain cancers. In certain cases, multisession radiosurgery is also performed using the mask. The workflow of frame versus frameless procedures is often altered, and is reliant on high-definition imaging, mostly MRI, done prior to dose planning. Since each CBCT takes 10-12 min to set up and acquire, co-register, and review with the treatment plan, and two CBCT scans are necessary to initiate the treatment plan, this workflow must be added to the beam on time. Although frame-based immobilization remains the predominant method to secure target fixation for problems suitable for single-session radiosurgery, the advent of a mask immobilization technique has proven valuable for a select group of patients. It also provides a non-invasive method to perform multisession or fractionated radiation in patients for whom traditional single-session radiosurgery is not feasible.


Assuntos
Encefalopatias , Tomografia Computadorizada de Feixe Cônico , Radiocirurgia , Planejamento da Radioterapia Assistida por Computador , Restrição Física , Encefalopatias/diagnóstico por imagem , Encefalopatias/radioterapia , Encefalopatias/cirurgia , Tomografia Computadorizada de Feixe Cônico/instrumentação , Tomografia Computadorizada de Feixe Cônico/métodos , Humanos , Radiocirurgia/instrumentação , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Restrição Física/instrumentação , Restrição Física/métodos
19.
Prog Neurol Surg ; 34: 9-18, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31096232

RESUMO

A decision to develop a stereotactic radiosurgery center and install the first 201 cobalt-60 Gamma Knife in Pittsburgh was made in 1981 after gathering regional and leadership support. This was part of a 7-year quest that required overcoming barriers to a new technology unfamiliar to US regulatory authorities and insurance companies. The first patient was treated in August 1987. Since that time our center has installed each succeeding Gamma Knife device developed. During an initial 30-year experience we performed more than 14,750 patient procedures. In addition to patient care our Center's goal was to develop a major teaching and clinical research program that eventually led to the training of more than 2,500 physicians and medical physicists, the publication of more than 600 peer-reviewed clinical outcome research studies, and 4 books. This report summarizes the rationale for acquisition, the challenges and the early years, and then the evolution of our center which installed the first US 201 source Gamma Knife.


Assuntos
Centros Médicos Acadêmicos , Radioisótopos de Cobalto , Radiocirurgia , Centros Médicos Acadêmicos/história , Centros Médicos Acadêmicos/estatística & dados numéricos , História do Século XX , História do Século XXI , Humanos , América do Norte , Radiocirurgia/educação , Radiocirurgia/história , Radiocirurgia/instrumentação , Radiocirurgia/estatística & dados numéricos
20.
J Appl Clin Med Phys ; 20(5): 21-26, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31055877

RESUMO

PURPOSE: Characterize the intra-fraction motion management (IFMM) system found on the Gamma Knife Icon (GKI), including spatial accuracy, latency, temporal performance, and overall effect on delivered dose. METHODS: A phantom was constructed, consisting of a three-axis translation mount, a remote motorized flipper, and a thermoplastic sphere surrounding a radiation detector. An infrared marker was placed on the translation mount secured to the flipper. The spatial accuracy of the IFMM was measured via the translation mount in all Cartesian planes. The detector was centered at the radiation focal point. A remote signal was used to move the marker out of the IFMM tolerance and pause the beam. A two-channel electrometer was used to record the signals from the detector and the flipper when motion was signaled. These signals determined the latency and temporal performance of the GKI. RESULTS: The spatial accuracy of the IFMM was found to be <0.1 mm. The measured latency was <200 ms. The dose difference with five interruptions was <0.5%. CONCLUSION: This work provides a quantitative characterization of the GKI IFMM system as required by the Nuclear Regulatory Commission. This provides a methodology for GKI users to satisfy these requirements using common laboratory equipment in lieu of a commercial solution.


Assuntos
Movimento , Neoplasias/cirurgia , Imagens de Fantasmas , Radiocirurgia/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Desenho de Equipamento , Humanos , Radiometria/métodos , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA