RESUMEN
When the Brooklyn Waterworks opened in 1859, it was one of America's most advanced water and sewer systems. Yet after Brooklyn was annexed by New York City, the waterworks' history slipped into obscurity, despite having a now-famous champion: the "poet of America," Walt Whitman, whose brother worked on the project. This article shows the Brooklyn poet's fierce, multiyear lobbying effort for the waterworks in various newspapers and introduces a wealth of newly recovered Whitman writings on the issue. As a journalist, Whitman exemplifies the nineteenth-century press as an intermediary between expert engineers and popular readers. The poet brought precise expertise, translated engineers' technical arguments into everyday language for his readers, and fought the resulting day-to-day political battles over construction in print. Whitman, then, is an underappreciated case study of the confluence of technology, public health, and local journalism.
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Periodismo , Historia del Siglo XIX , Ciudad de Nueva York , Periodismo/historia , Ingeniería Sanitaria/historia , Humanos , Periódicos como Asunto/historia , Salud Pública/historiaRESUMEN
INTRODUCTION: NRG protocols for glioblastoma allow for clinical target volume (CTV) reductions at natural barriers; however, literature examining CTV contouring and the relevant white matter pathways is lacking. This study proposes consensus CTV guidelines, with a focus on areas of controversy while highlighting common errors in glioblastoma target delineation. METHODS: Ten academic radiation oncologists specializing in brain tumor treatment contoured CTVs on four glioblastoma cases. CTV expansions were based on NRG trial guidelines. Contour consensus was assessed and summarized by kappa statistics. A meeting was held to discuss the mathematically averaged contours and form consensus contours and recommendations. RESULTS: Contours of the cavity plus enhancement (mean kappa 0.69) and T2-FLAIR signal (mean kappa 0.74) showed moderate to substantial agreement. Experts were asked to trim off anatomic barriers while respecting pathways of spread to develop their CTVs. Submitted CTV_4600 (mean kappa 0.80) and CTV_6000 (mean kappa 0.81) contours showed substantial to near perfect agreement. Simultaneous truth and performance level estimation (STAPLE) contours were then reviewed and modified by group consensus. Anatomic trimming reduced the amount of total brain tissue planned for radiation targeting by a 13.6% (range 8.7-17.9%) mean proportional reduction. Areas for close scrutiny of target delineation were described, with accompanying recommendations. CONCLUSIONS: Consensus contouring guidelines were established based on expert contours. Careful delineation of anatomic pathways and barriers to spread can spare radiation to uninvolved tissue without compromising target coverage. Further study is necessary to accurately define optimal target volumes beyond isometric expansion techniques for individual patients.
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Neoplasias Encefálicas/radioterapia , Glioblastoma/radioterapia , Guías de Práctica Clínica como Asunto , Planificación de la Radioterapia Asistida por Computador/métodos , Neoplasias Encefálicas/diagnóstico por imagen , Protocolos Clínicos , Glioblastoma/diagnóstico por imagen , Humanos , Imagen por Resonancia MagnéticaRESUMEN
PURPOSE: To determine the rate of marginal relapse, progression-free survival (PFS), and overall survival (OS) in patients with pediatric low-grade glioma (PLGG) treated with conformal radiation therapy (CRT) with a clinical target volume (CTV) margin of 5 mm in the Children's Oncology Group trial ACNS0221. METHODS AND MATERIALS: Patients aged 3 to 21 years with unresectable progressive, recurrent, or residual PLGG were eligible for this study. Patients younger than 10 years were required to have received at least 1 chemotherapy course. Patients with neurofibromatosis type I were not eligible. All patients underwent magnetic resonance imaging-based planning and received 54 Gy CRT in 30 fractions with a 5-mm CTV margin. RESULTS: Of 85 eligible patients (median age, 13.6 years) treated between March 2006 and December 2010, 14 were younger than 10 years and 36 received prior chemotherapy. Sixty-six had pilocytic astrocytoma, 15 had other histologic subtypes, and 4 had unbiopsied chiasmatic lesions. Events included 23 relapses (19 central, 4 distant, and no marginal) and 7 deaths. At a median follow-up of 5.15 years, 5-year PFS was 71% ± 6% and OS was 93% ± 4%. Male sex (P = .068) and large tumor size (P = .050) trended toward significance for association with decreased PFS. Age, histology, tumor location, time between diagnosis and study entry, and MIB-1 status were not associated with PFS. OS was negatively associated with male sex (P = .064), non-pilocytic astrocytoma histology (P = .010), and large tumor size (P = .0089). CONCLUSIONS: For patients with PLGG, CRT with a CTV margin of 5 mm yields an acceptable PFS and does not lead to a high rate of marginal relapse.
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Glioma/patología , Glioma/radioterapia , Radioterapia Conformacional , Adolescente , Niño , Preescolar , Femenino , Humanos , Masculino , Clasificación del Tumor , Recurrencia , Análisis de Supervivencia , Resultado del Tratamiento , Adulto JovenRESUMEN
Sebaceous carcinomas (SeC) are cutaneous malignancies that, in rare cases, metastasize and prove fatal. Here we report whole-exome sequencing on 32 SeC, revealing distinct mutational classes that explain both cancer ontogeny and clinical course. A UV-damage signature predominates in 10/32 samples, while nine show microsatellite instability (MSI) profiles. UV-damage SeC exhibited poorly differentiated, infiltrative histopathology compared to MSI signature SeC (p = 0.003), features previously associated with dissemination. Moreover, UV-damage SeC transcriptomes and anatomic distribution closely resemble those of cutaneous squamous cell carcinomas (SCC), implicating sun-exposed keratinocytes as a cell of origin. Like SCC, this UV-damage subclass harbors a high somatic mutation burden with >50 mutations per Mb, predicting immunotherapeutic response. In contrast, ocular SeC acquires far fewer mutations without a dominant signature, but show frequent truncations in the ZNF750 epidermal differentiation regulator. Our data exemplify how different mutational processes convergently drive histopathologically related but clinically distinct cancers.
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Carcinoma de Células Escamosas/genética , Neoplasias del Ojo/genética , Inestabilidad de Microsatélites , Mutación , Neoplasias de las Glándulas Sebáceas/genética , Neoplasias Cutáneas/genética , Carcinoma de Células Escamosas/clasificación , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/patología , Análisis Mutacional de ADN , Diagnóstico Diferencial , Exoma , Neoplasias del Ojo/clasificación , Neoplasias del Ojo/diagnóstico , Neoplasias del Ojo/patología , Humanos , Queratinocitos/metabolismo , Queratinocitos/patología , Queratinocitos/efectos de la radiación , Repeticiones de Microsatélite , Neoplasias de las Glándulas Sebáceas/clasificación , Neoplasias de las Glándulas Sebáceas/diagnóstico , Neoplasias de las Glándulas Sebáceas/patología , Neoplasias Cutáneas/clasificación , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/etiología , Terminología como Asunto , Transcriptoma , Rayos Ultravioleta/efectos adversos , Secuenciación del ExomaRESUMEN
Heterotopic ossification (HO) of the bone is defined as a benign condition in which abnormal bone formation occurs in soft tissue. One of the most common prophylactic treatments for HO is radiation therapy (RT). This study retrospectively reviewed 20 patients younger than the age of 40 who received radiation to prevent HO in a single fraction of 7 Gray. The purpose of this study is to assess the risk of a second malignancy in these patients by recreating their treatment fields and contouring organs at risk to estimate the radiation dose absorbed by normal tissues outside the radiation treatment field. Diagnostic computed tomography (CT) scans for each patient were used to recreate treatment fields and to calculate dose to structures of interest. The distance from the field edge to each structure and its depth was recorded. Dose measurements in a water phantom were performed for the range of depths, distances, and field sizes used in the actual treatment plans. Computer-generated doses were compared to estimates based on measurement. The structure dose recorded was the higher dose generated between the 2 methods. Scatter dose was recorded to the rectum, bladder, sigmoid colon, small bowel, ovaries and utero-cervix in female patients, and prostate and gonads in male patients. In some patients, there is considerable dose received by certain organs from scatter because of their proximity to the radiation field. The average dose to the ovarian region was 4.125Gy with a range of 1.085 to 6.228Gy. The risk estimate for these patients ranged from 0.16% to 0.93%. The average total lifetime risk estimate for the bladder in all patients is 0.22% and the average total lifetime risk estimate for the remainder organs in all patients is 1.25%. In conclusions, proper shielding created from multileaf collimators (MLCs), blocks, and shields should always be used when possible.
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Neoplasias Inducidas por Radiación/etiología , Osificación Heterotópica/prevención & control , Femenino , Humanos , Masculino , Ovario/efectos de la radiación , Protección Radiológica , Dosificación Radioterapéutica , Estudios Retrospectivos , Riesgo , Tomografía Computarizada por Rayos X , Vejiga Urinaria/efectos de la radiaciónRESUMEN
Pro-oxidative stressors can suppress host immunity due to their ability to generate oxidized lipid agonists of the platelet-activating factor-receptor (PAF-R). As radiation therapy also induces reactive oxygen species, the present studies were designed to define whether ionizing radiation could generate PAF-R agonists and if these lipids could subvert host immunity. We demonstrate that radiation exposure of multiple tumor cell lines in-vitro, tumors in-vivo, and human subjects undergoing radiation therapy for skin tumors all generate PAF-R agonists. Structural characterization of radiation-induced PAF-R agonistic activity revealed PAF and multiple oxidized glycerophosphocholines that are produced non-enzymatically. In a murine melanoma tumor model, irradiation of one tumor augmented the growth of the other (non-treated) tumor in a PAF-R-dependent process blocked by a cyclooxygenase-2 inhibitor. These results indicate a novel pathway by which PAF-R agonists produced as a byproduct of radiation therapy could result in tumor treatment failure, and offer important insights into potential therapeutic strategies that could improve the overall antitumor effectiveness of radiation therapy regimens.
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Antioxidantes/farmacología , Melanoma/terapia , Factor de Activación Plaquetaria/agonistas , Glicoproteínas de Membrana Plaquetaria/agonistas , Receptores Acoplados a Proteínas G/agonistas , Neoplasias Cutáneas/terapia , Rayos Ultravioleta , Animales , Femenino , Humanos , Melanoma/inmunología , Melanoma/metabolismo , Melanoma/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Desnudos , Estrés Oxidativo , Glicoproteínas de Membrana Plaquetaria/fisiología , Receptores Acoplados a Proteínas G/fisiología , Transducción de Señal , Neoplasias Cutáneas/inmunología , Neoplasias Cutáneas/metabolismo , Neoplasias Cutáneas/secundario , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
PURPOSE: To describe volume changes following proton beam therapy (PBT) for juvenile pilocytic astrocytoma (JPA), we analyzed post-PBT magnetic resonance imaging (MRI) to clarify survivorship, response rate, and the concept of pseudoprogression. MATERIALS AND METHODS: Pediatric patients with a histologic diagnosis of JPA after a biopsy or subtotal resection and at least 4 post-PBT MRIs were retrospectively reviewed. After PBT, tumors were contoured on follow-up T1-contrasted MRIs, and 3-dimensional volumes were plotted against time, with thresholds for progressive disease and partial response. Patterns of response, pseudoprogression, and progression were uncovered. Post-PBT clinical course was described by the need for further intervention and survivorship. RESULTS: Fifteen patients with a median of 10 follow-up MRIs made up this report: 60% were heavily pretreated with multiple lines of chemotherapy, and 67% had undergone subtotal resection. With a median follow-up of 55.3 months after a median of 5400 centigray equivalents PBT, estimates of 5-year overall survival and intervention-free survival were 93% and 72%, respectively. The crude response rate of 73% included pseudoprogressing patients, who comprised 20% of the entire cohort; the phenomenon peaked between 3 and 8 months and resolved by 18 months. One nonresponder expired from progression. Post-PBT intervention was required in 53% of patients, with 1 patient resuming chemotherapy. There were no further resections or radiotherapy. One patient developed acute lymphoblastic leukemia, and another developed biopsy-proven radionecrosis. CONCLUSION: The PBT for inoperable/progressive JPA provided 72% 5-year intervention-free survival in heavily pretreated patients. Although most patients responded, 20% demonstrated pseudoprogression. The need for post-PBT surveillance for progression and treatment-induced sequelae should not be underestimated in this extended survivorship cohort.
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Neoplasias Encefálicas/secundario , Anticonvulsivantes/uso terapéutico , Edema Encefálico/tratamiento farmacológico , Edema Encefálico/etiología , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/terapia , Terapia Combinada , Irradiación Craneana/efectos adversos , Irradiación Craneana/métodos , Glucocorticoides/uso terapéutico , Humanos , Cuidados Paliativos/métodos , Pronóstico , Radiocirugia/métodos , Convulsiones/tratamiento farmacológico , Convulsiones/etiología , Técnicas EstereotáxicasRESUMEN
OBJECTIVE: Midline and central lesions of the brain requiring conventional radiotherapy (RT) present complex difficulties in dose avoidance to organs at risk (OAR). In either definitive or adjuvant settings, proper RT coverage of these lesions involves unnecessary treatment of large volumes of normal brain. We propose a class solution for these lesions using proton radiotherapy (PrT). MATERIALS AND METHODS: The records of the Indiana University Health Proton Therapy Center were reviewed for patients presenting between January 1, 2005 and October 1, 2013 with midline central nervous system (CNS) lesions. Twenty-four patients were identified. After Institutional Review Board approval was granted, their dosimetry was reviewed for target volume doses and OAR dose avoidance. RESULTS: For these cases, meningiomas were the most common histology (8 cases), and next most prevalent were craniopharyngiomas (6 cases). The others were various different deep midline brain tumors (10 cases). In all cases, fields formed by vertex and/or anterior/posterior superior oblique PrT beams along the midsagittal plane were used to provide coverage with minimal dose to the brain stem or to the cerebral hemispheres. The median prescribed dose to the planning target volume for treating these patients was 54.0 Gy RBE (range 48.6-62.5) with a mean dose of 53.5 Gy RBE. The average of the mean doses to the brain stems using these fields in the 24 plans was 18.4 Gy RBE (range 0.0-44.7). Similarly, the average of the mean doses to the hippocampi was 15.8 Gy RBE (range 0.0-52.6). CONCLUSIONS: We consider these patients to be optimally treated with PrT. The use of modified midsagittal PrT schemas allows for the treatment of midline CNS lesions with sparing of most of the uninvolved brain.
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Neoplasias Encefálicas/radioterapia , Sistema Nervioso Central/patología , Sistema Nervioso Central/efectos de la radiación , Terapia de Protones/efectos adversos , Neoplasias Encefálicas/patología , Relación Dosis-Respuesta en la Radiación , Humanos , Órganos en Riesgo , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Radioterapia Conformacional/efectos adversos , Radioterapia Conformacional/métodosRESUMEN
We report clinical outcomes of proton therapy in patients with World Health Organization grade 2 (atypical) meningiomas. Between 2005 and 2013, 22 patients with atypical meningiomas were treated to a median dose of 63 Gy (RBE) using proton therapy, as an adjuvant therapy after surgery (n = 12) or for recurrence or progression of residual tumor (n = 10). Six patients had presumed radiation-induced meningiomas, but none had received prior radiotherapy for their meningioma. The median follow-up time after radiation was 39 months (range 7-104) and all patients remain alive at last follow-up. The 5-year estimate of local control was 71.1% (95% CI 49.3-92.9%). The 5-year estimate of local control was 87.5% following a radiation dose >60 Gy (RBE), compared to 50.0% for ≤ 60 Gy (RBE) (p = 0.038). The 5-year estimate of neuraxis dissemination was 5% (95% CI 0-14.6%) and 6.2% (95% CI 0-18.2%) for metastases outside of the central nervous system. Radiation necrosis was observed in one patient with a history of prior cranial irradiation. Fractionated proton therapy was associated with favorable tumor control rates for grade 2 meningiomas. Prospective studies are needed to define the optimal radiation dose for high-grade meningiomas.
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Neoplasias Meníngeas/radioterapia , Meningioma/radioterapia , Recurrencia Local de Neoplasia/radioterapia , Terapia de Protones , Terapia Recuperativa , Adolescente , Adulto , Anciano , Femenino , Estudios de Seguimiento , Humanos , Masculino , Neoplasias Meníngeas/patología , Meningioma/patología , Persona de Mediana Edad , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Pronóstico , Estudios Retrospectivos , Tasa de Supervivencia , Adulto JovenRESUMEN
BACKGROUND: Previous reports establish low risk of complications in pediatric treatments under anesthesia/sedation (A/S) in the outpatient setting. Here, we present our institutional experience with A/S by age and gender in children receiving daily proton RT. METHODS: After Institutional Review Board approval, we reviewed our center's records between 9/9/2004 and 6/30/2013 with respect to age and gender of A/S requirement in our pediatric patients (defined as patients ≤18 years of age). RESULTS: Of 390 patients treated in this era, 182 were girls. Children aged ≤3 invariably required A/S; and by age 7-8, approximately half of patients do not. For pediatric patients ≥ 12 years of age, approximately 10% may require A/S for different reasons. There was no difference by gender. CONCLUSIONS: Beyond age 3, the requirement for A/S decreases in an age-dependent fashion, with a small cadre of older children having difficulty enough with sustained immobilization that A/S is necessary. In our experience, there is no difference in A/S requirement by gender.
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Anestesia/estadística & datos numéricos , Neoplasias/radioterapia , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia de Intensidad Modulada/métodos , Adolescente , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Lactante , Masculino , Neoplasias/patología , Pediatría , Dosificación Radioterapéutica , Factores de TiempoRESUMEN
OBJECTIVE: Few data exist on evaluating utilization patterns of radiotherapy (RT) at the end of life (EOL) in children. Metastatic disease in pediatric patients is not pathognomonic for palliative treatment intent; further complicating the issue are complexities surrounding the very select population of children receiving proton therapy (PrT). We compared data for RT and PrT in terms of death rate within 30 days. METHODS: We performed chart reviews for patients receiving radiation therapy at age ≤21 years treated at Indiana University Health Proton Therapy Center (IUHPTC) between June 2008 and June 2013 and University of Miami Radiation Oncology Department (UM) between June 2000 and June 2013. Included were patients not completing prescribed courses of RT, and those dying within 30 days of therapy. Comparison was made of differences between practice data for PrT and conventional RT. RESULTS: At IUHPTC, 2 children of 272 did not complete their courses and died within 30 days (0.7%). At UM, data are available for 425 children; 9 did not complete their courses and 7 died within 30 days (1.6%). Neither the number of patients who did not complete treatment nor the 30-day death rates (P=.21) for PrT and RT were significantly different. CONCLUSIONS: Delivery of RT for children at EOL is complex. Frequency of RT at EOL in children occurs in is <2% of cases, and is not significantly less frequent in the proton milieu. This appears to be about an order of magnitude less than in adults.
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Neoplasias/radioterapia , Cuidados Paliativos/estadística & datos numéricos , Cuidado Terminal/estadística & datos numéricos , Adolescente , Niño , Preescolar , Femenino , Florida , Humanos , Indiana , Lactante , Masculino , Radioterapia/estadística & datos numéricos , Estudios Retrospectivos , Adulto JovenRESUMEN
Many radiotherapy centers desire proton therapy (PrT) because the unique physical dosimetry allows for improved dose distribution in some clinical situations. These benefits are best described in skull base and many pediatric lesions. However, there are significant challenges to PrT that are overlooked or simply ignored when centers embark on the PrT journey particularly as it applies to pediatric patients.In this review, we review the Indiana University Health Proton Therapy Center experience regarding benefits and drawbacks of PrT for pediatric patients. In conclusion, centers aspiring to PrT capacity should be aware not only of the well-described benefits in some clinical scenarios, but also the significant challenges to the modality in its practical clinical application.
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Neoplasias/radioterapia , Terapia de Protones , Adolescente , Anestesia General/economía , Anestesia General/métodos , Niño , Protección a la Infancia/legislación & jurisprudencia , Preescolar , Irradiación Craneoespinal/efectos adversos , Irradiación Craneoespinal/economía , Irradiación Craneoespinal/métodos , Humanos , Siembra Neoplásica , Consentimiento Paterno/legislación & jurisprudencia , Terapia de Protones/economía , Terapia de Protones/instrumentación , Terapia de Protones/métodos , Dosis de Radiación , Escoliosis/prevención & control , Neoplasias de la Columna Vertebral/radioterapiaRESUMEN
PURPOSE: Multi-modality therapy has resulted in improved survival for childhood malignancies. The Children's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers provide practitioners with exposure- and risk-based recommendations for the surveillance and management of asymptomatic survivors who are at least 2 years from completion of therapy. This review outlines the pathophysiology and risks for oral and dental late effects in pediatric cancer survivors and the rationale for oral and dental screening recommended by the Children's Oncology Group. METHODS: An English literature search for oral and dental complications of childhood cancer treatment was undertaken via MEDLINE and encompassed January 1975 to January 2013. Proposed guideline content based on the literature review was approved by a multi-disciplinary panel of survivorship experts and scored according to a modified version of the National Comprehensive Cancer Network "Categories of Consensus" system. RESULTS: The Children's Oncology Group oral-dental panel selected 85 relevant citations. Childhood cancer therapy may impact tooth development, salivary function, craniofacial development, and temporomandibular joint function placing some childhood cancer survivors at an increased risk for poor oral and dental health. Additionally, head and neck radiation and hematopoietic stem cell transplantation increase the risk of subsequent malignant neoplasms in the oral cavity. Survivors require routine dental care to evaluate for potential side effects and initiate early treatment. CONCLUSIONS: Certain childhood cancer survivors are at an increased risk for poor oral and dental health. Early identification of oral and dental morbidity and early interventions can optimize health and quality of life.
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Atención Odontológica/métodos , Neoplasias/fisiopatología , Neoplasias/terapia , Niño , Humanos , SobrevivientesRESUMEN
Gamma Knife Radiosurgery (GKRS) has been reported in the treatment of brainstem metastases while dose volume toxicity thresholds remain mostly undefined. A retrospective review of 52 brainstem metastases in 44 patients treated with GKRS was completed. A median dose of 18 Gy (range 10-22 Gy) was prescribed to the tumor margin (median 50 % isodose). 25 patients had undergone previous whole brain radiation therapy. Toxicity was graded by the LENT-SOMA scale. Mean and median follow-up was 10 and 6 months. Only 3 of the 44 patients are living. Multiple brain metastases were treated in 75 % of patients. Median size of lesions was 0.134 cc, (range 0.013-6.600 cc). Overall survival rate at 1 year was 32 % (95 % CI 51.0-20.1 %) with a median survival time of 6 months (95 % CI 5.0-16.5). Local control rate at 6 months and 1 year was 88 % (95 % CI 70-95 %) and 74 % (95 % CI 52-87 %). Cause of death was neurologic in 17 patients, non-neurologic in 20 patients, and unknown in four. Four patients experienced treatment related toxicities. Univariate analysis of tumor volume revealed that volume greater than 1.0 cc predicted for toxicity. A strategy of using lower marginal doses with GKRS to brain stem metastases appears to lead to a lower local control rate than seen with lesions treated within the standard dose range in other locations. Tumor size greater than 1.0 cc predicted for treatment-related toxicity.
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Neoplasias del Tronco Encefálico/secundario , Neoplasias del Tronco Encefálico/cirugía , Radiocirugia/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Tronco Encefálico/patología , Neoplasias del Tronco Encefálico/patología , Carcinoma de Pulmón de Células no Pequeñas/patología , Causas de Muerte , Fraccionamiento de la Dosis de Radiación , Relación Dosis-Respuesta en la Radiación , Femenino , Estudios de Seguimiento , Humanos , Estimación de Kaplan-Meier , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Tiempo , Resultado del Tratamiento , Carga TumoralRESUMEN
BACKGROUND: The increase in relative biological effectiveness (RBE) of proton beams at the distal edge of the spread out Bragg peak (SOBP) is a well-known phenomenon that is difficult to quantify accurately in vivo. For purposes of treatment planning, disallowing the distal SOBP to fall within vulnerable tissues hampers sparing to the extent possible with proton beam therapy (PBT). We propose the distal RBE uncertainty may be straightforwardly mitigated with a technique we call "range modulation". With range modulation, the distal falloff is smeared, reducing both the dose and average RBE over the terminal few millimeters of the SOBP. METHODS: One patient plan was selected to serve as an example for direct comparison of image-guided radiotherapy plans using non-range modulation PBT (NRMPBT), and range-modulation PBT (RMPBT). An additional plan using RMPBT was created to represent a re-treatment scenario (RMPBTrt) using a vertex beam. Planning statistics regarding dose, volume of the planning targets, and color images of the plans are shown. RESULTS: The three plans generated for this patient reveal that in all cases dosimetric and device manufacturing advantages are able to be achieved using RMPBT. Organ at risk (OAR) doses to critical structures such as the cochleae, optic apparatus, hypothalamus, and temporal lobes can be selectively spared using this method. Concerns about the location of the RBE that did significantly impact beam selection and treatment planning no longer have the same impact on the process, allowing these structures to be spared dose and subsequent associated issues. CONCLUSIONS: This present study has illustrated that RMPBT can improve OAR sparing while giving equivalent coverage to target volumes relative to traditional PBT methods while avoiding the increased RBE at the end of the beam. It has proven easy to design and implement and robust in our planning process. The method underscores the need to optimize treatment plans in PBT for both traditional energy dose in gray (Gy) and biologic dose (RBE).
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Terapia de Protones , Radiometría/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen/métodos , Encéfalo/efectos de la radiación , Neoplasias Encefálicas/radioterapia , Irradiación Craneana/efectos adversos , Irradiación Craneana/normas , Relación Dosis-Respuesta en la Radiación , Glioma/radioterapia , Humanos , Seguridad del Paciente , Terapia de Protones/efectos adversos , Radiometría/normas , Planificación de la Radioterapia Asistida por Computador/normas , Radioterapia Guiada por Imagen/normas , Efectividad Biológica RelativaRESUMEN
Vein of Galen aneurysmal malformations (VGAMs) are uncommon congenital malformations arising from fistulous communication with the median vein of the prosencephalon, a primitive precursor of midline cerebral venous structures. Angiographic embolization is the primary modality for treatment given historically poor microsurgical outcomes. Only a few reports of treatment by Gamma Knife radiosurgery (GKRS) exist in the literature, and the results are variable. The authors present 2 cases of VGAM in which GKRS provided definitive treatment with good outcome: one case involving antenatal presentation of a high-output, mural-type VGAM with complex clinical course refractory to multiple embolic procedures, and the other a choroidal-type VGAM presenting with hemorrhage in an adult and without a feasible embolic approach. With discussion of these cases and review of the literature, the authors advocate inclusion of GKRS as a therapeutic option for treatment of these complex lesions.