Cranial Nerve II

PubMed Central

Gillig, Paulette Marie; Sanders, Richard D.

2009-01-01

This article contains a brief review of the anatomy of the visual system, a survey of diseases of the retina, optic nerve and lesions of the optic chiasm, and other visual field defects of special interest to the psychiatrist. It also includes a presentation of the corticothalamic mechanisms, differential diagnosis, and various manifestations of visual illusions, and simple and complex visual hallucinations, as well as the differential diagnoses of these various visual phenomena. PMID:19855858

Anatomy and physiology of the afferent visual system.

PubMed

Prasad, Sashank; Galetta, Steven L

2011-01-01

The efficient organization of the human afferent visual system meets enormous computational challenges. Once visual information is received by the eye, the signal is relayed by the retina, optic nerve, chiasm, tracts, lateral geniculate nucleus, and optic radiations to the striate cortex and extrastriate association cortices for final visual processing. At each stage, the functional organization of these circuits is derived from their anatomical and structural relationships. In the retina, photoreceptors convert photons of light to an electrochemical signal that is relayed to retinal ganglion cells. Ganglion cell axons course through the optic nerve, and their partial decussation in the chiasm brings together corresponding inputs from each eye. Some inputs follow pathways to mediate pupil light reflexes and circadian rhythms. However, the majority of inputs arrive at the lateral geniculate nucleus, which relays visual information via second-order neurons that course through the optic radiations to arrive in striate cortex. Feedback mechanisms from higher cortical areas shape the neuronal responses in early visual areas, supporting coherent visual perception. Detailed knowledge of the anatomy of the afferent visual system, in combination with skilled examination, allows precise localization of neuropathological processes and guides effective diagnosis and management of neuro-ophthalmic disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

Isolated primary central nervous system lymphoma arising from the optic chiasm.

PubMed

Vassal, F; Pommier, B; Boutet, C; Forest, F; Campolmi, N; Nuti, C

2014-12-01

A 58-year-old previously healthy woman rapidly developed progressive bilateral visual loss. Magnetic resonance imaging revealed a bulging appearance of the optic chiasm, with homogeneous enhancement after gadolinium administration, which suggested an optic glioma or inflammatory disease. In the absence of (para)clinical clues for a specific diagnosis despite extensive investigation, a biopsy of one optic nerve was performed, resulting in a diagnosis of non-Hodgkin B-cell lymphoma. There was no evidence of any other ocular or systemic involvement, therefore the conclusion was that this immunocompetent patient had a primary central nervous system lymphoma isolated in the anterior visual pathway. Treatment included two cycles of polychemotherapy (rituximab, methotrexate, carmustine, etoposide, methylprednisolone), followed by autologous peripheral blood stem cell transplantation and rituximab plus cytarabine consolidation therapy. Subsequently, the patient exhibited significant improvement in vision, and was still disease-free at the 1-year follow-up examination. The aim of the present paper was to provide well-documented clinical, radiological, and intraoperative features of isolated primary malignant lymphoma arising from the anterior visual pathway. A better recognition of this rare pathological entity is necessary for clinicians who may encounter similar presentations, as prompt management is crucial for both a visual and vital prognosis. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Shh-ushing Midline Crossing through Remote Protein Transport.

PubMed

Herrera, Eloísa; Sitko, Austen A; Bovolenta, Paola

2018-01-17

Shh contributes to neural circuit formation with different mechanisms. In this issue, Peng and colleagues (2018) identify a novel trans-axonal mechanism by which Shh derived from contralateral projecting retinal ganglion cells prevents midline crossing of Boc-expressing ipsilateral axons at the optic chiasm. Copyright © 2018 Elsevier Inc. All rights reserved.

VRPD Novel Combinatory Approaches to Repair Visual System After Optic Nerve Damage

DTIC Science & Technology

2015-05-01

At 4 and 8 weeks after injury, retinas were immunostained with an antibody against beta III tubulin (TUJ1) to estimate RGC survival. The degree of...Optic chiasm presentation of Semaphorin6D in the context of Plexin-A1 and Nr- CAM promotes retinal axon midline crossing. Neuron 74, 676–690. Leaver...for Nr- CAM in the patterning of binocular visual pathways. Neuron 50, 535–547. Williams, S.E., Mann, F., Erskine, L., Sakurai, T., Wei, S., Rossi, D.J

[Estimation of the quality of life 8-year-old child with bilateral anophthalmia].

PubMed

Sredzińska-Kita, Dorota; Mrugacz, Małgorzata; Bakunowicz-Łazarczyk, Alina

2009-01-01

The main aim of our work was to estimate the physical and psychomotor development and the arrangement to the daily life for a 8-year-old girl with inborn bilateral anophthalmia. The basic ophthalmic, pediatric and neurological examinations were performed with additional genetic and radiological examinations. The ophthalmic and MRI examination find out the absence of the eyeballs, optic nerves, optic chiasm, optic tracts and optic radiation. Anophthalmia limits in a big grade an independent life of the child. However, currently the girl's development indicates for good intellectual abilities what is promising for future independent life and professional work.

ALDH1A3 loss of function causes bilateral anophthalmia/microphthalmia and hypoplasia of the optic nerve and optic chiasm.

PubMed

Yahyavi, Mani; Abouzeid, Hana; Gawdat, Ghada; de Preux, Anne-Sophie; Xiao, Tong; Bardakjian, Tanya; Schneider, Adele; Choi, Alex; Jorgenson, Eric; Baier, Herwig; El Sada, Mohamad; Schorderet, Daniel F; Slavotinek, Anne M

2013-08-15

The major active retinoid, all-trans retinoic acid, has long been recognized as critical for the development of several organs, including the eye. Mutations in STRA6, the gene encoding the cellular receptor for vitamin A, in patients with Matthew-Wood syndrome and anophthalmia/microphthalmia (A/M), have previously demonstrated the importance of retinol metabolism in human eye disease. We used homozygosity mapping combined with next-generation sequencing to interrogate patients with anophthalmia and microphthalmia for new causative genes. We used whole-exome and whole-genome sequencing to study a family with two affected brothers with bilateral A/M and a simplex case with bilateral anophthalmia and hypoplasia of the optic nerve and optic chiasm. Analysis of novel sequence variants revealed homozygosity for two nonsense mutations in ALDH1A3, c.568A>G, predicting p.Lys190*, in the familial cases, and c.1165A>T, predicting p.Lys389*, in the simplex case. Both mutations predict nonsense-mediated decay and complete loss of function. We performed antisense morpholino (MO) studies in Danio rerio to characterize the developmental effects of loss of Aldh1a3 function. MO-injected larvae showed a significant reduction in eye size, and aberrant axonal projections to the tectum were noted. We conclude that ALDH1A3 loss of function causes anophthalmia and aberrant eye development in humans and in animal model systems.

ALDH1A3 loss of function causes bilateral anophthalmia/microphthalmia and hypoplasia of the optic nerve and optic chiasm

PubMed Central

Yahyavi, Mani; Abouzeid, Hana; Gawdat, Ghada; de Preux, Anne-Sophie; Xiao, Tong; Bardakjian, Tanya; Schneider, Adele; Choi, Alex; Jorgenson, Eric; Baier, Herwig; El Sada, Mohamad; Schorderet, Daniel F.; Slavotinek, Anne M.

2013-01-01

The major active retinoid, all-trans retinoic acid, has long been recognized as critical for the development of several organs, including the eye. Mutations in STRA6, the gene encoding the cellular receptor for vitamin A, in patients with Matthew–Wood syndrome and anophthalmia/microphthalmia (A/M), have previously demonstrated the importance of retinol metabolism in human eye disease. We used homozygosity mapping combined with next-generation sequencing to interrogate patients with anophthalmia and microphthalmia for new causative genes. We used whole-exome and whole-genome sequencing to study a family with two affected brothers with bilateral A/M and a simplex case with bilateral anophthalmia and hypoplasia of the optic nerve and optic chiasm. Analysis of novel sequence variants revealed homozygosity for two nonsense mutations in ALDH1A3, c.568A>G, predicting p.Lys190*, in the familial cases, and c.1165A>T, predicting p.Lys389*, in the simplex case. Both mutations predict nonsense-mediated decay and complete loss of function. We performed antisense morpholino (MO) studies in Danio rerio to characterize the developmental effects of loss of Aldh1a3 function. MO-injected larvae showed a significant reduction in eye size, and aberrant axonal projections to the tectum were noted. We conclude that ALDH1A3 loss of function causes anophthalmia and aberrant eye development in humans and in animal model systems. PMID:23591992

Acute postretinal blindness: ophthalmologic, neurologic, and magnetic resonance imaging findings in dogs and cats (seven cases).

PubMed

Seruca, Cristina; Ródenas, Sergio; Leiva, Marta; Peña, Teresa; Añor, Sònia

2010-09-01

To describe the ophthalmologic, neurologic, and magnetic resonance imaging (MRI) findings of seven animals with acute postretinal blindness as sole neurologic deficit. Medical records were reviewed to identify dogs and cats with postretinal blindness of acute presentation, that had a cranial MRI performed as part of the diagnostic workup. Only animals lacking other neurologic signs at presentation were included. Complete physical, ophthalmic, and neurologic examinations, routine laboratory evaluations, thoracic radiographs, abdominal ultrasound, electroretinography, and brain MRI were performed in all animals. Cerebrospinal fluid analysis and postmortem histopathologic results were recorded when available. Four dogs and three cats met the inclusion criteria. Lesions affecting the visual pathways were observed on magnetic resonance (MR) images in six cases. Location, extension, and MRI features were described. Neuroanatomic localization included: olfactory region with involvement of the optic chiasm (n = 4), pituitary fossa with involvement of the optic chiasm and optic tracts (n = 1), and optic nerves (n = 1). Of all lesions detected, five were consistent with intracranial tumors (two meningiomas, one pituitary tumor, two nasal tumors with intracranial extension), and one with bilateral optic neuritis that was confirmed by cerebrospinal fluid analysis. Histologic diagnosis was obtained in four cases and included one meningioma, one pituitary carcinoma, one nasal osteosarcoma, and one nasal carcinoma. Central nervous system (CNS) disease should be considered in dogs and cats with acute blindness, even when other neurologic deficits are absent. This study emphasizes the relevance of MRI as a diagnostic tool for detection and characterization of CNS lesions affecting the visual pathways.

SU-C-BRA-04: Automated Segmentation of Head-And-Neck CT Images for Radiotherapy Treatment Planning Via Multi-Atlas Machine Learning (MAML)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, X; Gao, H; Sharp, G

Purpose: Accurate image segmentation is a crucial step during image guided radiation therapy. This work proposes multi-atlas machine learning (MAML) algorithm for automated segmentation of head-and-neck CT images. Methods: As the first step, the algorithm utilizes normalized mutual information as similarity metric, affine registration combined with multiresolution B-Spline registration, and then fuses together using the label fusion strategy via Plastimatch. As the second step, the following feature selection strategy is proposed to extract five feature components from reference or atlas images: intensity (I), distance map (D), box (B), center of gravity (C) and stable point (S). The box feature Bmore » is novel. It describes a relative position from each point to minimum inscribed rectangle of ROI. The center-of-gravity feature C is the 3D Euclidean distance from a sample point to the ROI center of gravity, and then S is the distance of the sample point to the landmarks. Then, we adopt random forest (RF) in Scikit-learn, a Python module integrating a wide range of state-of-the-art machine learning algorithms as classifier. Different feature and atlas strategies are used for different ROIs for improved performance, such as multi-atlas strategy with reference box for brainstem, and single-atlas strategy with reference landmark for optic chiasm. Results: The algorithm was validated on a set of 33 CT images with manual contours using a leave-one-out cross-validation strategy. Dice similarity coefficients between manual contours and automated contours were calculated: the proposed MAML method had an improvement from 0.79 to 0.83 for brainstem and 0.11 to 0.52 for optic chiasm with respect to multi-atlas segmentation method (MA). Conclusion: A MAML method has been proposed for automated segmentation of head-and-neck CT images with improved performance. It provides the comparable result in brainstem and the improved result in optic chiasm compared with MA. Xuhua Ren and Hao Gao were partially supported by the NSFC (#11405105), the 973 Program (#2015CB856000), and the Shanghai Pujiang Talent Program (#14PJ1404500).« less

Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function.

PubMed

McDannold, Nathan; Zhang, Yong-Zhi; Power, Chanikarn; Jolesz, Ferenc; Vykhodtseva, Natalia

2013-11-01

Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging-guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively producing sharply demarcated lesions in deep brain structures while preserving function in adjacent nerves. Because of low vascularity--and thus a low microbubble concentration--some large white matter tracts appear to have some natural resistance to this type of ablation compared with gray matter. While future work is needed to develop methods of monitoring the procedure and establishing its safety at deep brain targets, the technique does appear to be a potential solution that allows FUS ablation of deep brain targets while sparing adjacent nerve structures.

Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function

PubMed Central

McDannold, Nathan; Zhang, Yong-Zhi; Power, Chanikarn; Jolesz, Ferenc; Vykhodtseva, Natalia

2014-01-01

Object Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging–guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. Methods In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. Results Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. Conclusions This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively producing sharply demarcated lesions in deep brain structures while preserving function in adjacent nerves. Because of low vascularity—and thus a low microbubble concentration—some large white matter tracts appear to have some natural resistance to this type of ablation compared with gray matter. While future work is needed to develop methods of monitoring the procedure and establishing its safety at deep brain targets, the technique does appear to be a potential solution that allows FUS ablation of deep brain targets while sparing adjacent nerve structures. PMID:24010975

Predictive Models of Human Visual Processes in Aerosystems.

DTIC Science & Technology

1979-11-01

Physiology, 190:139-154. Wiesel, T. N. and D. H. Hubel, 1966. Spatial and chromatic interactions in the lateral geniculate body of the rhesus monkey...receiving a disproportionate share as reflected in the magnification factor in the retinotopic map of the dorsal lateral geniculate (Malpeli and Baker...optic chiasm before reaching its targets in the dorsal region of the lateral geniculate of the thalmus and the superior colliculus in the brain stem

Lost in the jungle: new hurdles for optic nerve axon regeneration.

PubMed

Pernet, Vincent; Schwab, Martin E

2014-07-01

The poor regenerative capacity of injured central nervous system (CNS) axons leads to permanent neurological deficits after brain, spinal cord, or optic nerve lesions. In the optic nerve, recent studies showed that stimulation of the cytokine or mammalian target of rapamycin (mTOR) signaling pathways potently enhances sprouting and regeneration of injured retinal ganglion cell axons in adult mice, but does not allow the majority of axons to reach their main cerebral targets. New analyses have revealed axon navigation defects in the optic nerve and at the optic chiasm under conditions of strong growth stimulation. We propose that a balanced growth stimulatory treatment will have to be combined with guidance factors and suppression of local growth inhibitory factors to obtain the full regeneration of long CNS axonal tracts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Segmentation of organs-at-risks in head and neck CT images using convolutional neural networks

PubMed Central

Ibragimov, Bulat; Xing, Lei

2017-01-01

Purpose Accurate segmentation of organs-at-risks (OARs) is the key step for efficient planning of radiation therapy for head and neck (HaN) cancer treatment. In the work, we proposed the first deep learning-based algorithm, for segmentation of OARs in HaN CT images, and compared its performance against state-of-the-art automated segmentation algorithms, commercial software and inter-observer variability. Methods Convolutional neural networks (CNNs) – a concept from the field of deep learning – were used to study consistent intensity patterns of OARs from training CT images and to segment the OAR in a previously unseen test CT image. For CNN training, we extracted a representative number of positive intensity patches around voxels that belong to the OAR of interest in training CT images, and negative intensity patches around voxels that belong to the surrounding structures. These patches then passed through a sequence of CNN layers that captured local image features such as corners, end-points and edges, and combined them into more complex high-order features that can efficiently describe the OAR. The trained network was applied to classify voxels in a region of interest in the test image where the corresponding OAR is expected to be located. We then smoothed the obtained classification results by using Markov random fields algorithm. We finally extracted the largest connected component of the smoothed voxels classified as the OAR by CNN, performed dilate-erode operations to remov cavities of the component, which resulted in segmentation of the OAR in the test image. Results The performance of CNNs was validated on segmentation of spinal cord, mandible, parotid glands, submandibular glands, larynx, pharynx, eye globes, optic nerves and optic chiasm using 50 CT images. The obtained segmentation results varied from 37.4% Dice coefficient (DSC) for chiasm to 89.5% DSC for mandible. We also analyzed the performance of state-of-the-art algorithms and commercial software reported in the literature, and observed that CNNs demonstrate similar or superior performance on segmentation of spinal cord, mandible, parotid glands, larynx, pharynx, eye globes and optic nerves, but inferior performance on segmentation of submandibular glands and optic chiasm. Conclusion We concluded that convolution neural networks can accurately segment most of OARs using a representative database of 50 HaN CT images. At the same time, inclusion of additional information, e.g. MR images, may be beneficial for some OARs with poorly-visible boundaries. PMID:28205307

Neuroanatomy-based matrix-guided trimming protocol for the rat brain.

PubMed

Defazio, Rossella; Criado, Ana; Zantedeschi, Valentina; Scanziani, Eugenio

2015-02-01

Brain trimming through defined neuroanatomical landmarks is recommended to obtain consistent sections in rat toxicity studies. In this article, we describe a matrix-guided trimming protocol that uses channels to reproduce coronal levels of anatomical landmarks. Both setup phase and validation study were performed on Han Wistar male rats (Crl:WI(Han)), 10-week-old, with bodyweight of 298 ± 29 (SD) g, using a matrix (ASI-Instruments(®), Houston, TX) fitted for brains of rats with 200 to 400 g bodyweight. In the setup phase, we identified eight channels, that is, 6, 8, 10, 12, 14, 16, 19, and 21, matching the recommended landmarks midway to the optic chiasm, frontal pole, optic chiasm, infundibulum, mamillary bodies, midbrain, middle cerebellum, and posterior cerebellum, respectively. In the validation study, we trimmed the immersion-fixed brains of 60 rats using the selected channels to determine how consistently the channels reproduced anatomical landmarks. Percentage of success (i.e., presence of expected targets for each level) ranged from 89 to 100%. Where 100% success was not achieved, it was noted that the shift in brain trimming was toward the caudal pole. In conclusion, we developed and validated a trimming protocol for the rat brain that allow comparable extensiveness, homology, and relevance of coronal sections as the landmark-guided trimming with the advantage of being quickly learned by technicians. © 2014 by The Author(s).

Expanded Endoscopic Endonasal Resection of Retrochiasmatic Craniopharyngioma.

PubMed

Davanzo, Justin R; Goyal, Neerav; Zacharia, Brad E

2018-02-01

This video abstract demonstrates the use of the expanded endoscopic endonasal approach for the resection of a retrochiasmatic craniopharyngioma. These tumors are notoriously difficult to treat, and many approaches have been tried to facilitate safe and effective resection. The endoscopic endonasal approach has been increasingly utilized for selected sellar/suprasellar pathology. We present the case of a 39-year-old man who was found to have a cystic, partially calcified suprasellar mass consistent with a craniopharyngioma. To facilitate robust skull base repair, a vascularized nasoseptal flap was harvested. A wide sphenoidotomy was performed and the sella and tuberculum were exposed. After the dural opening and arachnoid dissection, the stalk was identified, merging seamlessly with the tumor capsule. The lesion was then internally debulked with the use of an ultrasonic aspirator. The capsule was then dissected off of the optic chiasm, thalamus, and hypothalamus. The cavity was inspected with an angled endoscope to ensure complete resection. A multilayered reconstruction was performed using autologous fascia lata, the previously harvested nasoseptal flap, and dural sealant. Postoperatively, the patient did have expected panhypopituitarism but remained neurologically intact and had improvement in his vision. In conclusion, this video demonstrates how an expanded endonasal approach can be used to safely resect a craniopharyngioma, even when in close proximity to delicate structures such as the optic chiasm. The link to the video can be found at: https://youtu.be/tahjHmrXhc4 .

Mid-aortic syndrome with renovascular hypertension and multisystem involvement in a girl with familiar neurofibromatosis von Recklinghausen type 1.

PubMed

Petrak, Borivoj; Bendova, Sarka; Seeman, Tomas; Klein, Tibor; Lisy, Jiri; Zatrapa, Tomas; Marikova, Tana

2007-12-01

Neurofibromatosis von Recklinghausen type 1 (NF1) is an autosomal dominant neurocutaneous disorder affecting one in 3 000-4 000 individuals. Mid-aortic syndrome (MAS) is a rare condition characterized by segmental narrowing of abdominal aorta and stenosis of its major branches - mainly renal arteries, including manifestation of renovascular hypertension. MAS can be caused by different diseases, including NF1. A 9 years old girl with primary diagnosis of NF1 combined with renovascular hypertension due to MAS, suffered of bilateral optic and chiasm glioma, pubertas praecox, speech disorder, light mental retardation and scoliosis. We have found a mutation in exone 34 of the NF1 gene (17q11.2). Her father has been also diagnosed with NF1 and hypertension developed at early age. He has the same mutation in exone 34 of NF1 gene. The girl is currently treated with conservative antihypertensive medication with positive effect. Bilateral optic and chiasm glioma are asymptomatic at the time and they had been without progress over period of time. Any vascular surgery, neurosurgical and oncological therapy are not indicated at the present time. This article is a summary of clinical findings in patient with NF1 due to NF1 gene mutation in exone 34. It confirms the importance of complex multidisciplinar approach to examination and taking care of NF1 patients and their families.

Novel treatment for radiation optic neuropathy with intravenous bevacizumab.

PubMed

Farooq, Osman; Lincoff, Norah S; Saikali, Nicolas; Prasad, Dheerendra; Miletich, Robert S; Mechtler, Laszlo L

2012-12-01

Radiation optic neuropathy is a devastating form of vision loss that can occur months to years after radiation therapy for tumors and other lesions located in close proximity to the visual pathways. We present the case of a 24-year-old woman who underwent external beam radiation for treatment of a tectal pilocytic astrocytoma, and 5 years later she developed bilateral radiation optic neuropathy and radiation necrosis of the right temporal lobe. We opted to treat her with intravenous bevacizumab with 3 doses every 3 weeks, as well as dexamethasone and pentoxifylline. After the first infusion of bevacizumab, the patient noted improvement in vision and color vision, and a follow-up magnetic resonance imaging study showed that the previous enhancement of the optic nerves and chiasm was diminishing. Her vision improved dramatically and has remained stable over a 3-year period.

SU-F-T-339: Comparison Between Coplanar and Non-Coplanar RapidArc Approach of Hippocampal-Sparing Whole Brain Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, B; Kim, J

Purpose: To compare the dosimetry of coplanar and non-coplanar RapidArc whole brain plans for hippocampal sparing Methods: We studied the RapidArc plans of patient with brain metastases, with the prescription of 3750 cGy in 15 fractions. The coplanar approach used a full clockwise (CW) arc and a full counterclockwise (CCW) arc, with the couch angle to be 0°. The non-coplanar approach used a full arc with a couch angle of 0°, and a partial arc with a couch angle of 90°. Treatment planning system is Eclipse Ver. 11. Constraints for eyes, lens, brainstem, optical nerves and chiasm are employed inmore » the optimization so that these OARs’ dose are below tolerance. Constraints for hippocampus are employed so that they receive dose as low as possible while maintain good coverage to whole brain. The beam delivery machine is Varian 21 IX. T1-weighted MRI images were used for hippocampus contouring. Results: The target coverage index for coplanar and non-coplanar RapidArc plans are 94.9% and 95.4%, respectively, with homogeneity index of 0.223 vs 0.226, which is defined as (D2% – D98%)/Dmean of target volume. V95 and V100 are 99.0% and 94.8% for coplanar plan, vs 99.1% and 95.4% for non-coplanar plan, while the mean dose of hippocampus are 1244.5 cGy for coplanar plan vs 1212.3 cGy for non-coplanar plan. Dose for eyes, lens, optical nerves, optical chiasm and brainstem are all below tolerance. Conclusion: Coplanar RapidArc plan provides good target coverage while achieves good hippocampal sparing, and there is no benefit to use non-coplanar approach.« less

[Microsurgical anatomy importance of A1-anterior communicating artery complex].

PubMed

Monroy-Sosa, Alejandro; Pérez-Cruz, Julio César; Reyes-Soto, Gervith; Delgado-Hernández, Carlos; Macías-Duvignau, Mario Alberto; Delgado-Reyes, Luis

2013-01-01

The anterior cerebral artery originates from the bifurcation of the internal carotid artery lateral to the optic chiasm, then joins with its contralateral counterpart via the anterior communicating artery. A1-anterior communicating artery complex is the most frequent anatomical variants and is the major site of aneurysms between 30 to 37%. Know the anatomy microsurgical, variants anatomical and importance of complex precommunicating segment-artery anterior communicating in surgery neurological of the pathology vascular, mainly aneurysms, in Mexican population. The study was performed in 30 brains injected. Microanatomy was studied (length and diameter) of A1-anterior communicating artery complex and its variants. 60 segments A1, the average length of left side was 11.35 mm and 11.84 mm was right. The average diameter of left was 1.67 mm and the right was 1.64 mm. The average number of perforators on the left side was 7.9 and the right side was 7.5. Anterior communicating artery was found in 29 brains of the optic chiasm, its course depended on the length of the A1 segment. The average length of the segment was 2.84 mm, the average diameter was 1.41 mm and the average number of perforators was 3.27. A1-anterior communicating artery complex variants were found in 18 (60%) and the presence of two blister-like aneurysms. It is necessary to understand the A1-anterior communicating artery complex microanatomy of its variants to have a three-dimensional vision during aneurysm surgery.

Stereotactic radiotherapy for malignancies involving the trigeminal and facial nerves.

PubMed

Cuneo, K C; Zagar, T M; Brizel, D M; Yoo, D S; Hoang, J K; Chang, Z; Wang, Z; Yin, F F; Das, S K; Green, S; Ready, N; Bhatti, M T; Kaylie, D M; Becker, A; Sampson, J H; Kirkpatrick, J P

2012-06-01

Involvement of a cranial nerve caries a poor prognosis for many malignancies. Recurrent or residual disease in the trigeminal or facial nerve after primary therapy poses a challenge due to the location of the nerve in the skull base, the proximity to the brain, brainstem, cavernous sinus, and optic apparatus and the resulting complex geometry. Surgical resection caries a high risk of morbidity and is often not an option for these patients. Stereotactic radiosurgery and radiotherapy are potential treatment options for patients with cancer involving the trigeminal or facial nerve. These techniques can deliver high doses of radiation to complex volumes while sparing adjacent critical structures. In the current study, seven cases of cancer involving the trigeminal or facial nerve are presented. These patients had unresectable recurrent or residual disease after definitive local therapy. Each patient was treated with stereotactic radiation therapy using a linear accelerator based system. A multidisciplinary approach including neuroradiology and surgical oncology was used to delineate target volumes. Treatment was well tolerated with no acute grade 3 or higher toxicity. One patient who was reirradiated experienced cerebral radionecrosis with mild symptoms. Four of the seven patients treated had no evidence of disease after a median follow up of 12 months (range 2-24 months). A dosimetric analysis was performed to compare intensity modulated fractionated stereotactic radiation therapy (IM-FSRT) to a 3D conformal technique. The dose to 90% (D90) of the brainstem was lower with the IM-FSRT plan by a mean of 13.5 Gy. The D95 to the ipsilateral optic nerve was also reduced with IM-FSRT by 12.2 Gy and the D95 for the optic chiasm was lower with FSRT by 16.3 Gy. Treatment of malignancies involving a cranial nerve requires a multidisciplinary approach. Use of an IM-FSRT technique with a micro-multileaf collimator resulted in a lower dose to the brainstem, optic nerves and chiasm for each case examined.

Traversing the Chiasms of Lived Experiences: Phenomenological Illuminations for Practitioner Research

ERIC Educational Resources Information Center

Lukenchuk, Antonina

2006-01-01

This article juxtaposes Merleau-Ponty's phenomenology of sense perception and practitioner research as well as demonstrating their potential to become integrated into powerful educational research and practice. The paper elaborates on Merleau-Ponty's metaphor of "chiasm", extends its symbolic meaning to practitioner research and illustrates its…

The use of portable intraoperative computed tomography scanning for real-time image guidance: a pilot cadaver study.

PubMed

Das, Subinoy; Maeso, Patricia A; Figueroa, Ramon E; Senior, Brent A; Delgaudio, John M; Sillers, Michael J; Schlosser, Rod J; Kountakis, Stilianos E

2008-01-01

This study was performed to assess the feasibility of using intraoperative computed tomography (CT) to provide real-time updates to image guidance systems (IGSs) during surgery. The xCAT ENT portable intraoperative CT scanner (Xoran Technologies, Ann Arbor, MI) was used to acquire scans before, midway, and at the end of six cadaver dissections during the Southern States Rhinology Course, Augusta, GA, in October 2006. These scans were used to recalibrate three different IGSs used during the dissection. Time measurements were recorded and dosimetry was obtained from the cornea, sphenoid sinus (near the optic chiasm), and from the operative field during acquisition of the images. IGS accuracy was determined at the skull base and lamina papyracea. Surgeons were interviewed on benefits of real-time updates to the IGS after completion of dissections. The xCAT ENT scanner was compatible with all three IGS platforms. The average time to update the IGS was 13 minutes. Radiation doses to the cornea were 620 mrad per scan, and optic chiasm was 800 mrad/scan. The accuracy at the anterior skull base improved from 1.58 to 0.62 mm (p=0.026). The accuracy at the posterior skull base improved from 1.46 to 0.71 mm (p=0.014). The accuracy at the lamina was not significantly changed. Intraoperative portable CT scanning with real-time IGS updates is feasible and likely would add little additional time. Accuracy is improved at the skull base. Prospective studies on actual patients are warranted.

Primary Central Nervous System Lymphoma of Optic Chiasma: Endoscopic Endonasal Treatment.

PubMed

Ozdemir, Evin Singar; Yildirim, Ali Erdem; Can, Aslihan Yavas

2018-01-01

Isolated primary central nervous system lymphoma arising from anterior visual pathway is very rare. A 76-year-old immunocompetent previously healthy man presented bilateral decreased visual acuity in 1 month. Pituitary magnetic resonans imaging (MRI) showed a lobulated mass with homogeneous enhancement after gadolinium administration that arising from optic chiasm suggested that inflammatory disease or an optic glioma. The patient underwent an extended endoscopic endonasal transsphenoidal surgery. Postoperative course and outcomes were wonderful. Histopathological diagnosis was diffuse large B-cell lymphoma. The patient underwent investigations for systemic lymphomatous involvement, did not detect any evidence of systemic disease. In this case, we claimed that differential diagnoses of anterior visual pathway lesions are difficult because of similarity of lesions on clinical and radiological examinations. Biopsy is essential for these lesions. As a biopsy technique, endoscopic endonasal transsphenoidal approach is safer and more effective than open procedures.

Reversible Edema-Like Changes Along the Optic Tract Following Pipeline-Assisted Coiling of a Large Anterior Communicating Artery Aneurysm.

PubMed

La Pira, Biagia; Brinjikji, Waleed; Hunt, Christopher; Chen, John J; Lanzino, Giuseppe

2017-06-01

Aneurysmal volume expansion after endovascular treatment is caused by intra-aneurysmal thrombosis in the early postembolization period. Although postembolization mass effect on cranial nerves and other adjacent structures has been previously reported, we are unaware of reports involving the anterior visual pathway. A 66-year-old woman with a 2-week history of blurred vision without headache was found to have a large, unruptured anterior communicating artery aneurysm. One month after endovascular treatment of the aneurysm with coiling and flow diversion, the patient developed decreased vision in her right eye and a left homonymous hemianopia. Magnetic resonance imaging demonstrated compression of the right optic nerve, chiasm, and edema of the right optic tract. The patient was treated with a course of high dose corticosteroids, and over the course of several weeks, her vision improved and the optic tract edema resolved. We alert clinicians to this rare but potentially reversible visual complication of endovascular treatment of intracranial aneurysms.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokhrel, D; Sood, S; Badkul, R

Purpose: To compare dose distributions calculated using PB-hete vs. XVMC algorithms for SRT treatments of cavernous sinus tumors. Methods: Using PB-hete SRT, five patients with cavernous sinus tumors received the prescription dose of 25 Gy in 5 fractions for planning target volume PTV(V100%)=95%. Gross tumor volume (GTV) and organs at risk (OARs) were delineated on T1/T2 MRI-CT-fused images. PTV (range 2.1–84.3cc, mean=21.7cc) was generated using a 5mm uniform-margin around GTV. PB-hete SRT plans included a combination of non-coplanar conformal arcs/static beams delivered by Novalis-TX consisting of HD-MLCs and a 6MV-SRS(1000 MU/min) beam. Plans were re-optimized using XVMC algorithm with identicalmore » beam geometry and MLC positions. Comparison of plan specific PTV(V99%), maximal, mean, isocenter doses, and total monitor units(MUs) were evaluated. Maximal dose to OARs such as brainstem, optic-pathway, spinal cord, and lenses as well as normal tissue volume receiving 12Gy(V12) were compared between two algorithms. All analysis was performed using two-tailed paired t-tests of an upper-bound p-value of <0.05. Results: Using either algorithm, no dosimetrically significant differences in PTV coverage (PTVV99%,maximal, mean, isocenter doses) and total number of MUs were observed (all p-values >0.05, mean ratios within 2%). However, maximal doses to optic-chiasm and nerves were significantly under-predicted using PB-hete (p=0.04). Maximal brainstem, spinal cord, lens dose and V12 were all comparable between two algorithms, with exception of one patient with the largest PTV who exhibited 11% higher V12 with XVMC. Conclusion: Unlike lung tumors, XVMC and PB-hete treatment plans provided similar PTV coverage for cavernous sinus tumors. Majority of OARs doses were comparable between two algorithms, except for small structures such as optic chiasm/nerves which could potentially receive higher doses when using XVMC algorithm. Special attention may need to be paid on a case-by-case basis when planning for sinus SRT based on tumor size and location to OARs particularly the optic apparatus.« less

Extrinsic and intrinsic blood supply to the optic chiasm.

PubMed

Salaud, Céline; Ploteau, Stéphane; Blery, Pauline; Pilet, Paul; Armstrong, Olivier; Hamel, Antoine

2018-04-01

Although there have been many studies of the arterial cerebral blood supply, only seven have described the optic chiasm (OC) blood supply and their results are contradictory. The aim of this study was to analyze the extrinsic and intrinsic OC blood supply on cadaveric specimens using dissections and microcomputer tomography (Micro-CT). Thirteen human specimens were dissected and the internal or common carotid arteries were injected with red latex, China Ink with gelatin or barium sulfate. Three Micro-CTs were obtained to reveal the intrinsic blood supply to the OC. The superior hypophyseal arteries (SupHypA) (13/13) and posterior communicating artery (PCoA) (12/13) supplied the pial network on the inferior side of the OC. The first segment of the anterior cerebral artery (ACA) (10/10), SupHypA (7/10), the anterior communicating artery (ACoA) (9/10), and PComA (1/10) supplied the pial network of its superior side. The intrinsic OC blood supply was divided into three networks (two lateral and one central). Capillaries entering the OC originated principally from the inferior pial network. The lateral network capillaries had the same orientation as the visual lateral pathways, but the central network was not correlated with the nasal fibers crossing into the OC. There was no anastomosis in the pial or intrinsic networks. Only SupHypA, PCoA, ACoA, and ACA were involved in the OC blood supply. Because there was no extrinsic or intrinsic anastomosis, all arteries should be preserved. Tumor compression of the inferior intrinsic arterial network could contribute to visual defects. Clin. Anat. 31:432-440, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukumitsu, Nobuyoshi, E-mail: fukumitsun@yahoo.co.jp; Okumura, Toshiyuki; Mizumoto, Masashi

Purpose: To investigate the clinical features, prognostic factors, and toxicity of treatment for unresectable carcinomas of the nasal cavity and paranasal sinus (NCPS) treated with proton beam therapy (PBT). Methods and Materials: Seventeen patients (13 men, 4 women) with unresectable carcinomas of the NCPS who underwent PBT at University of Tsukuba between 2001 and 2007 were analyzed. The patients' median age was 62 years (range, 30-83 years). The tumors were located in the nasal cavity in 3 patients, the frontal sinus in 1, the ethmoid sinus in 9, and the maxillary sinus in 4. The clinical stage was Stage IVAmore » in 5 cases, IVB in 10, and recurrent in 2. The tumors were deemed unresectable for medical reasons in 16 patients and because of refusal at a previous hospital 4 months earlier in 1 patient. All the patients received PBT irradiation dose of 22-82.5 GyE and a total of 72.4-89.6 GyE over 30-64 fractions (median 78 GyE over 36 fractions) with X-ray, with attention not exceeding the delivery of 50 GyE to the optic chiasm and brainstem. Results: The overall survival rate was 47.1% at 2 years and 15.7% at 5 years, and the local control rate was 35.0% at 2 years and 17.5% at 5 years. Invasion of the frontal or sphenoid sinus was a prognostic factor for overall survival or local control. Late toxicity of more than Grade 3 was found in 2 patients (brain necrosis in 1 and ipsilateral blindness in 1); however, no mortal adverse effects were observed. Conclusion: Proton beam therapy enabled a reduced irradiation dose to the optic chiasm and brainstem, enabling the safe treatment of unresectable carcinomas in the NCPS. Superior or posterior extension of the tumor influenced patient outcome.« less

Retinitis Pigmentosa Sine Pigmento Mimicking a Chiasm Disease.

PubMed

Pellegrini, Francesco; Prosdocimo, Giovanni; Romano, Francesco; Interlandi, Emanuela

2017-08-01

A 75-year-old woman presented to her ophthalmologist complaining of visual loss for several years. The ophthalmic examination was remarkable for a bitemporal visual field defect. Magnetic resonance imaging (MRI) scan of the brain was normal without evidence of chiasm compression. Neuro-ophthalmic examination was consistent with a retinal rather than a chiasmal disease. Retinal multimodal imaging helped in the correct diagnosis of retinitis pigmentosa, later confirmed by genetic testing.

[Gradient-index (GRIN) endoscopic examinations from the inner structures of the optic nerve meninges].

PubMed

Sens, Frank Michael; Killer, Hanspeter Esriel; Meyer, Peter

2003-03-01

Due to the excellent image quality and the small outer diameter of the GRIN-(gradient index) endoscope tips we were able to examine the subdural and the subarachnoidal space of the optic nerve meninges by endoscopy. This examination was performed to obtain more information about the inner structure of the optic nerve meninges. In this post-mortem study 7 optic nerves were examined from the chiasm to the globe by GRIN endoscopy (Volpi, Schlieren, Switzerland), with an outer diameter of 0.89 mm, integrated optic of 0.5 mm diameter and an integrated fluid channel of 0.2 mm diameter. In all cases the endoscopic examination of the optic nerve meninges was technically easy to perform. It was possible to study the inner surface of the nerve sheaths and the nerve sheath spaces in close-up. We found horizontal and vertical cords on the inner surface of the dura mater, which could tighten by movements of the optic nerve. With a gradient-index (GRIN) endoscope we obtained new information about the inner structure of the optic nerve meninges. New theories about the changes of the optic nerve meninges during movements of the optic nerve may evolve from this study. Further studies with this new method should be encouraged.

Retinitis Pigmentosa Sine Pigmento Mimicking a Chiasm Disease

PubMed Central

Pellegrini, Francesco; Prosdocimo, Giovanni; Romano, Francesco; Interlandi, Emanuela

2017-01-01

ABSTRACT A 75-year-old woman presented to her ophthalmologist complaining of visual loss for several years. The ophthalmic examination was remarkable for a bitemporal visual field defect. Magnetic resonance imaging (MRI) scan of the brain was normal without evidence of chiasm compression. Neuro-ophthalmic examination was consistent with a retinal rather than a chiasmal disease. Retinal multimodal imaging helped in the correct diagnosis of retinitis pigmentosa, later confirmed by genetic testing. PMID:29344059

Expanded Endoscopic Transnasal Approach to the Chordoid Glioma of the Third Ventricle : The First Case Ever Reported.

PubMed

Zeinalizadeh, Mehdi; Sadrehosseini, Seyed Mousa; Tayebi Meybodi, Keyvan; Sharifabadi, Ali Heidari

2016-11-01

Chordoid glioma of the third ventricle is a rare and challenging tumor to surgery because of its unique anatomical location and its close juxtaposition to the neurovascular structures and hypothalamus. The authors report a case of chordoid glioma of the third ventricle in a 43-year-old woman, who presented with headache and somnolence. The tumor was approached by endoscopic transnasal technique with a favorable result. Histopathologic examination disclosed a neoplastic tissue composed of eosinophilic epithelioid cells, mucinous, periodic acid Schiff-diastase positive, extracellular matrix, and scattered lymphoplasmacytic infiltrates. The best treatment option remains controversial. Customarily, the surgical route to remove chordoid glioma is transcranial; however, the undersurface of the optic chiasm and optic nerves preclude an adequate surgical visualization. In contrast, an expanded endoscopic transnasal approach provides a direct midline corridor to this region without any brain retraction.

N-acetylaspartylglutamate: a transmitter candidate for the retinohypothalamic tract.

PubMed Central

Moffett, J R; Williamson, L; Palkovits, M; Namboodiri, M A

1990-01-01

The retinohypothalamic tract is the neural pathway mediating the photic entrainment of circadian rhythms in mammals. Important targets for these retinal fibers are the suprachiasmatic nuclei (SCN) of the hypothalamus, which are thought to be primary sites for the biological clock. The neurotransmitters that operate in this projection system have not yet been determined. Immunohistochemistry and radioimmunoassay performed with affinity-purified antibodies to N-acetylaspartylglutamate (NAAG) demonstrate that this neuron-specific dipeptide, which may act as an excitatory neurotransmitter, is localized extensively in the retinohypothalamic tract and its target zones, including the SCN. Optic nerve transections resulted in significant reductions in NAAG immunoreactivity in the optic chiasm and SCN. Analysis of NAAG concentrations in micropunches of SCN, by means of radioimmunoassay, showed approximately 50% reductions in NAAG levels. These results suggest that this peptide may act as one of the neurotransmitters involved in retinohypothalamic communication and circadian rhythm entrainment. Images PMID:1978319

Patterns of Individual Variation in Visual Pathway Structure and Function in the Sighted and Blind

PubMed Central

Datta, Ritobrato; Benson, Noah C.; Prasad, Sashank; Jacobson, Samuel G.; Cideciyan, Artur V.; Bridge, Holly; Watkins, Kate E.; Butt, Omar H.; Dain, Aleksandra S.; Brandes, Lauren; Gennatas, Efstathios D.

2016-01-01

Many structural and functional brain alterations accompany blindness, with substantial individual variation in these effects. In normally sighted people, there is correlated individual variation in some visual pathway structures. Here we examined if the changes in brain anatomy produced by blindness alter the patterns of anatomical variation found in the sighted. We derived eight measures of central visual pathway anatomy from a structural image of the brain from 59 sighted and 53 blind people. These measures showed highly significant differences in mean size between the sighted and blind cohorts. When we examined the measurements across individuals within each group we found three clusters of correlated variation, with V1 surface area and pericalcarine volume linked, and independent of the thickness of V1 cortex. These two clusters were in turn relatively independent of the volumes of the optic chiasm and lateral geniculate nucleus. This same pattern of variation in visual pathway anatomy was found in the sighted and the blind. Anatomical changes within these clusters were graded by the timing of onset of blindness, with those subjects with a post-natal onset of blindness having alterations in brain anatomy that were intermediate to those seen in the sighted and congenitally blind. Many of the blind and sighted subjects also contributed functional MRI measures of cross-modal responses within visual cortex, and a diffusion tensor imaging measure of fractional anisotropy within the optic radiations and the splenium of the corpus callosum. We again found group differences between the blind and sighted in these measures. The previously identified clusters of anatomical variation were also found to be differentially related to these additional measures: across subjects, V1 cortical thickness was related to cross-modal activation, and the volume of the optic chiasm and lateral geniculate was related to fractional anisotropy in the visual pathway. Our findings show that several of the structural and functional effects of blindness may be reduced to a smaller set of dimensions. It also seems that the changes in the brain that accompany blindness are on a continuum with normal variation found in the sighted. PMID:27812129

A rare presentation of craniopharyngioma: delayed puberty

PubMed Central

İnci, Mehmet Fatih; Özkan, Fuat; Bozkurt, Selim; Demir, Caner Feyzi

2012-01-01

Craniopharyngiomas are the most frequently encountered suprasellar tumours in children. Owing to the slow growth rate of these tumours, they are often quite large before becoming symptomatic. They are more common among children and older adults (55–74 years). Depending upon the direction of growth and tumour size, craniopharyngiomas can affect the hypothalamus, pituitary stalk, optic nerves and chiasm and carotid arteries. Compression of these neural and vascular structures frequently precipitates endocrine disorders, visual loss and an increased intracranial pressure. Hypopituitarism leading to a delayed puberty is a rare presentation of craniopharyngioma. The diagnosis of craniopharyngioma is usually made with the classic radiological imaging features based on CT and MRI. PMID:23195827

Planum sphenoidale meningioma leading to visual disturbance

PubMed Central

Lutwak, Nancy; Dill, Curt; Wieczorek, Rosemary

2011-01-01

A 60-year-old male presented with complaints of dizziness, which worsened with fatigue and a sense his balance was ‘off’. Initial physical examination was negative and the laboratory testing was unremarkable. Within weeks, the patient developed bilateral visual field deficits. MRI revealed an extra-axial mass which extended into the pituitary fossa and caused compression of the pituitary gland. The pituitary stalk was displaced posteriorly and the optic chiasm was compressed with displacement superiorly and posteriorly. The patient underwent a surgical resection. Diabetes insipidus developed postoperatively requiring a vasopressin drip. He also developed hypopituitarism after the resection with hypothyroidism, hypoadrenalism and hypogonadism. The patient requires testosterone, levothyroxine and hydrocortisone replacement and has mild residual bitemporal hemianopsia. PMID:22679053

Planum sphenoidale meningioma leading to visual disturbance.

PubMed

Lutwak, Nancy; Dill, Curt; Wieczorek, Rosemary

2011-08-31

A 60-year-old male presented with complaints of dizziness, which worsened with fatigue and a sense his balance was 'off'. Initial physical examination was negative and the laboratory testing was unremarkable. Within weeks, the patient developed bilateral visual field deficits. MRI revealed an extra-axial mass which extended into the pituitary fossa and caused compression of the pituitary gland. The pituitary stalk was displaced posteriorly and the optic chiasm was compressed with displacement superiorly and posteriorly. The patient underwent a surgical resection. Diabetes insipidus developed postoperatively requiring a vasopressin drip. He also developed hypopituitarism after the resection with hypothyroidism, hypoadrenalism and hypogonadism. The patient requires testosterone, levothyroxine and hydrocortisone replacement and has mild residual bitemporal hemianopsia.

Radiation-induced optic neuropathy: A magnetic resonance imaging study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guy, J.; Mancuso, A.; Beck, R.

1991-03-01

Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence ofmore » both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.« less

Comparison of manual and automatic segmentation methods for brain structures in the presence of space-occupying lesions: a multi-expert study

PubMed Central

Deeley, M A; Chen, A; Datteri, R; Noble, J; Cmelak, A; Donnelly, E; Malcolm, A; Moretti, L; Jaboin, J; Niermann, K; Yang, Eddy S; Yu, David S; Yei, F; Koyama, T; Ding, G X; Dawant, B M

2011-01-01

The purpose of this work was to characterize expert variation in segmentation of intracranial structures pertinent to radiation therapy, and to assess a registration-driven atlas-based segmentation algorithm in that context. Eight experts were recruited to segment the brainstem, optic chiasm, optic nerves, and eyes, of 20 patients who underwent therapy for large space-occupying tumors. Performance variability was assessed through three geometric measures: volume, Dice similarity coefficient, and Euclidean distance. In addition, two simulated ground truth segmentations were calculated via the simultaneous truth and performance level estimation (STAPLE) algorithm and a novel application of probability maps. The experts and automatic system were found to generate structures of similar volume, though the experts exhibited higher variation with respect to tubular structures. No difference was found between the mean Dice coefficient (DSC) of the automatic and expert delineations as a group at a 5% significance level over all cases and organs. The larger structures of the brainstem and eyes exhibited mean DSC of approximately 0.8–0.9, whereas the tubular chiasm and nerves were lower, approximately 0.4–0.5. Similarly low DSC have been reported previously without the context of several experts and patient volumes. This study, however, provides evidence that experts are similarly challenged. The average maximum distances (maximum inside, maximum outside) from a simulated ground truth ranged from (−4.3, +5.4) mm for the automatic system to (−3.9, +7.5) mm for the experts considered as a group. Over all the structures in a rank of true positive rates at a 2 mm threshold from the simulated ground truth, the automatic system ranked second of the nine raters. This work underscores the need for large scale studies utilizing statistically robust numbers of patients and experts in evaluating quality of automatic algorithms. PMID:21725140

Circadian Behavioral Responses to Light and Optic Chiasm-Evoked Glutamatergic EPSCs in the Suprachiasmatic Nucleus of ipRGC Conditional vGlut2 Knock-Out Mice

PubMed Central

2018-01-01

Abstract Intrinsically photosensitive retinal ganglion cells (ipRGCs) innervate the hypothalamic suprachiasmatic nucleus (SCN), a circadian oscillator that functions as a biological clock. ipRGCs use vesicular glutamate transporter 2 (vGlut2) to package glutamate into synaptic vesicles and light-evoked resetting of the SCN circadian clock is widely attributed to ipRGC glutamatergic neurotransmission. Pituitary adenylate cyclase-activating polypeptide (PACAP) is also packaged into vesicles in ipRGCs and PACAP may be coreleased with glutamate in the SCN. vGlut2 has been conditionally deleted in ipRGCs in mice [conditional knock-outs (cKOs)] and their aberrant photoentrainment and residual attenuated light responses have been ascribed to ipRGC PACAP release. However, there is no direct evidence that all ipRGC glutamatergic neurotransmission is eliminated in vGlut2 cKOs. Here, we examined two lines of ipRGC vGlut2 cKO mice for SCN-mediated behavioral responses under several lighting conditions and for ipRGC glutamatergic neurotransmission in the SCN. Circadian behavioral responses varied from a very limited response to light to near normal photoentrainment. After collecting behavioral data, hypothalamic slices were prepared and evoked EPSCs (eEPSCs) were recorded from SCN neurons by stimulating the optic chiasm. In cKOs, glutamatergic eEPSCs were recorded and all eEPSC parameters examined (stimulus threshold, amplitude, rise time or time-to-peak and stimulus strength to evoke a maximal response) were similar to controls. We conclude that a variable number but functionally significant percentage of ipRGCs in two vGlut2 cKO mouse lines continue to release glutamate. Thus, the residual SCN-mediated light responses in these cKO mouse lines cannot be attributed solely to ipRGC PACAP release. PMID:29756029

Comparison of manual and automatic segmentation methods for brain structures in the presence of space-occupying lesions: a multi-expert study

NASA Astrophysics Data System (ADS)

Deeley, M. A.; Chen, A.; Datteri, R.; Noble, J. H.; Cmelak, A. J.; Donnelly, E. F.; Malcolm, A. W.; Moretti, L.; Jaboin, J.; Niermann, K.; Yang, Eddy S.; Yu, David S.; Yei, F.; Koyama, T.; Ding, G. X.; Dawant, B. M.

2011-07-01

The purpose of this work was to characterize expert variation in segmentation of intracranial structures pertinent to radiation therapy, and to assess a registration-driven atlas-based segmentation algorithm in that context. Eight experts were recruited to segment the brainstem, optic chiasm, optic nerves, and eyes, of 20 patients who underwent therapy for large space-occupying tumors. Performance variability was assessed through three geometric measures: volume, Dice similarity coefficient, and Euclidean distance. In addition, two simulated ground truth segmentations were calculated via the simultaneous truth and performance level estimation algorithm and a novel application of probability maps. The experts and automatic system were found to generate structures of similar volume, though the experts exhibited higher variation with respect to tubular structures. No difference was found between the mean Dice similarity coefficient (DSC) of the automatic and expert delineations as a group at a 5% significance level over all cases and organs. The larger structures of the brainstem and eyes exhibited mean DSC of approximately 0.8-0.9, whereas the tubular chiasm and nerves were lower, approximately 0.4-0.5. Similarly low DSCs have been reported previously without the context of several experts and patient volumes. This study, however, provides evidence that experts are similarly challenged. The average maximum distances (maximum inside, maximum outside) from a simulated ground truth ranged from (-4.3, +5.4) mm for the automatic system to (-3.9, +7.5) mm for the experts considered as a group. Over all the structures in a rank of true positive rates at a 2 mm threshold from the simulated ground truth, the automatic system ranked second of the nine raters. This work underscores the need for large scale studies utilizing statistically robust numbers of patients and experts in evaluating quality of automatic algorithms.

SU-C-BRB-01: Automated Dose Deformation for Re-Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, S; Kainz, K; Li, X

Purpose: An objective of retreatment planning is to minimize dose to previously irradiated tissues. Conventional retreatment planning is based largely on best-guess superposition of the previous treatment’s isodose lines. In this study, we report a rigorous, automated retreatment planning process to minimize dose to previously irradiated organs at risk (OAR). Methods: Data for representative patients previously treated using helical tomotherapy and later retreated in the vicinity of the original disease site were retrospectively analyzed in an automated fashion using a prototype treatment planning system equipped with a retreatment planning module (Accuray, Inc.). The initial plan’s CT, structures, and planned dosemore » were input along with the retreatment CT and structure set. Using a deformable registration algorithm implemented in the module, the initially planned dose and structures were warped onto the retreatment CT. An integrated third-party sourced software (MIM, Inc.) was used to evaluate registration quality and to contour overlapping regions between isodose lines and OARs, providing additional constraints during retreatment planning. The resulting plan and the conventionally generated retreatment plan were compared. Results: Jacobian maps showed good quality registration between the initial plan and retreatment CTs. For a right orbit case, the dose deformation facilitated delineating the regions of the eyes and optic chiasm originally receiving 13 to 42 Gy. Using these regions as dose constraints, the new retreatment plan resulted in V50 reduction of 28% for the right eye and 8% for the optic chiasm, relative to the conventional plan. Meanwhile, differences in the PTV dose coverage were clinically insignificant. Conclusion: Automated retreatment planning with dose deformation and definition of previously-irradiated regions allowed for additional planning constraints to be defined to minimize re-irradiation of OARs. For serial organs that do not recover from radiation damage, this method provides a more precise and quantitative means to limit cumulative dose. This research is partially supported by Accuray, Inc.« less

Hemifield columns co-opt ocular dominance column structure in human achiasma.

PubMed

Olman, Cheryl A; Bao, Pinglei; Engel, Stephen A; Grant, Andrea N; Purington, Chris; Qiu, Cheng; Schallmo, Michael-Paul; Tjan, Bosco S

2018-01-01

In the absence of an optic chiasm, visual input to the right eye is represented in primary visual cortex (V1) in the right hemisphere, while visual input to the left eye activates V1 in the left hemisphere. Retinotopic mapping In V1 reveals that in each hemisphere left and right visual hemifield representations are overlaid (Hoffmann et al., 2012). To explain how overlapping hemifield representations in V1 do not impair vision, we tested the hypothesis that visual projections from nasal and temporal retina create interdigitated left and right visual hemifield representations in V1, similar to the ocular dominance columns observed in neurotypical subjects (Victor et al., 2000). We used high-resolution fMRI at 7T to measure the spatial distribution of responses to left- and right-hemifield stimulation in one achiasmic subject. T 2 -weighted 2D Spin Echo images were acquired at 0.8mm isotropic resolution. The left eye was occluded. To the right eye, a presentation of flickering checkerboards alternated between the left and right visual fields in a blocked stimulus design. The participant performed a demanding orientation-discrimination task at fixation. A general linear model was used to estimate the preference of voxels in V1 to left- and right-hemifield stimulation. The spatial distribution of voxels with significant preference for each hemifield showed interdigitated clusters which densely packed V1 in the right hemisphere. The spatial distribution of hemifield-preference voxels in the achiasmic subject was stable between two days of testing and comparable in scale to that of human ocular dominance columns. These results are the first in vivo evidence showing that visual hemifield representations interdigitate in achiasmic V1 following a similar developmental course to that of ocular dominance columns in V1 with intact optic chiasm. Copyright © 2017 Elsevier Inc. All rights reserved.

Recovery from diabetes insipidus and preservation of thyroid function after craniopharyngioma removal and pituitary stalk sectioning.

PubMed

Ogawa, Yoshikazu; Niizuma, Kuniyasu; Tominaga, Teiji

2017-11-01

Craniopharyngioma is a slow-growing tumor, but long-term tumor control with maintenance of quality of life is sometimes very difficult to achieve, and hypothalamic disturbance should be strictly avoided in the treatment. However, management of the pituitary gland and/or pituitary stalk varies among surgeons and institutions. This retrospective review identified 44 patients, 24 males and 20 females with craniopharyngiomas who were initially treated by surgery through the extended transsphenoidal approach with pituitary stalk sectioning at a single institute. If the tumor bed involved the posterior lobe of the pituitary gland, pituitary stalk, anterior and/or mid portion of the third ventricle floor, these structures were removed en-bloc together with the tumor. The closest attention was paid to preserve fine arteries running along the surface of optic chiasm and the lateral walls of the third ventricle. Surgical outcome and changes in postoperative endocrinological status were investigated. Gross total removal was achieved in 40 of 44 patients (91%), and all patients could discharge without autonomic and/or thermal disturbances. Tumor remnants were identified with tight adhesion to the perforating arteries in 2 cases, tight adhesion to mammillary bodies in 1, and optic chiasm in 1. Administration of anti-diuretic hormone could be discontinued in 23 of 44 patients (52.3%) with improved diabetes insipidus (DI), although no patient could discontinue glucocorticoid administration. Preservation of thyroid function was achieved in another 23 of 44 patients (52.3%), and recovery from DI was correlated with preservation of thyroid function (p=0.016). Pituitary dysfunction is partially reversible even with pituitary stalk sectioning. Regrowth of tumor in the anterior and/or mid portion of the third ventricle floor including pituitary stalk can possibly be prevented by aggressive tumor removal, and co-achievement of long-term tumor control with maintenance of quality of life could be possible to preserve the lateral wall of the third ventricle. Copyright © 2017 Elsevier B.V. All rights reserved.

Endoscopic Endonasal Surgery for Purely Intrathird Ventricle Craniopharyngioma.

PubMed

Nishioka, Hiroshi; Fukuhara, Noriaki; Yamaguchi-Okada, Mitsuo; Yamada, Shozo

2016-07-01

Extended endoscopic transsphenoidal surgery (EETS) is a safe and effective treatment for many suprasellar craniopharyngiomas, including those with third-ventricle involvement. Craniopharyngioma entirely within the third ventricle (purely intraventricular type), however, is generally regarded unsuitable for treatment with EETS. Three patients underwent total removal of a purely intraventricular craniopharyngioma with inferior extension via EETS by direct incision of the bulging, stretched ventricular floor and fine dissection from the ventricular wall. In 2 patients with an anteriorly displaced chiasm, the space between the chiasm and pituitary stalk created a wide corridor to the ventricle, whereas in the third case, in which the infrachiasmal space was somewhat narrowed, partial sacrifice of the pituitary gland was necessary to obtain sufficient space. Despite preservation of the stalk in 2 patients, hypopituitarism and diabetes insipidus developed after surgery. There was no other complication including obesity. Selected patients with purely intraventricular craniopharyngioma can be treated effectively and safely with EETS. Those with inferior extension in the interpeduncular fossa and anterior displacement of the chiasm may be suitable candidates. Copyright © 2016 Elsevier Inc. All rights reserved.

A study of the comparative anatomy of the brain of domestic ruminants using magnetic resonance imaging.

PubMed

Schmidt, M J; Langen, N; Klumpp, S; Nasirimanesh, F; Shirvanchi, P; Ondreka, N; Kramer, M

2012-01-01

Although magnetic resonance imaging has been used to examine the brain of domestic ruminants, detailed information relating the precise anatomical features in these species is lacking. In this study the brain structures of calves (Bos taurus domesticus), sheep (Ovis aries), goats (Capra hircus) and a mesaticephalic dog (Canis lupis familiaris) were examined using T2-weighed Turbo Spin Echo sequences; three-dimensional models based on high-resolution gradient echo scans were used to identify brain sulci and gyri in two-dimensional images. The ruminant brains examined were similar in structure and organisation to those of other mammals but particular features included the deep depression of the insula and the pronounced gyri of the cortices, the dominant position of the visual (optic nerve, optic chiasm and rostral colliculus) and olfactory (olfactory bulb, olfactory tracts and piriform lobe) systems, and the relatively large size of the diencephalon. Copyright © 2010 Elsevier Ltd. All rights reserved.

Single-session Gamma Knife radiosurgery for optic pathway/hypothalamic gliomas.

PubMed

El-Shehaby, Amr M N; Reda, Wael A; Abdel Karim, Khaled M; Emad Eldin, Reem M; Nabeel, Ahmed M

2016-12-01

OBJECTIVE Because of their critical and central location, it is deemed necessary to fractionate when considering irradiating optic pathway/hypothalamic gliomas. Stereotactic fractionated radiotherapy is considered safer when dealing with gliomas in this location. In this study, the safety and efficacy of single-session stereotactic radiosurgery for optic pathway/hypothalamic gliomas were reviewed. METHODS Between December 2004 and June 2014, 22 patients with optic pathway/hypothalamic gliomas were treated by single-session Gamma Knife radiosurgery. Twenty patients were available for follow-up for a minimum of 1 year after treatment. The patients were 5 to 43 years (median 16 years) of age. The tumor volume was 0.15 to 18.2 cm 3 (median 3.1 cm 3 ). The prescription dose ranged from 8 to 14 Gy (median 11.5 Gy). RESULTS The mean follow-up period was 43 months. Five tumors involved the optic nerve only, and 15 tumors involved the chiasm/hypothalamus. Two patients died during the follow-up period. The tumors shrank in 12 cases, remained stable in 6 cases, and progressed in 2 cases, thereby making the tumor control rate 90%. Vision remained stable in 12 cases, improved in 6 cases, and worsened in 2 cases in which there was tumor progression. Progression-free survival was 83% at 3 years. CONCLUSIONS The initial results indicate that single-session Gamma Knife radiosurgery is a safe and effective treatment option for optic pathway/hypothalamic gliomas.

Blunt forehead trauma and optic canal involvement: finite element analysis of anterior skull base and orbit on causes of vision impairment.

PubMed

Huempfner-Hierl, Heike; Bohne, Alexander; Wollny, Gert; Sterker, Ina; Hierl, Thomas

2015-10-01

Clinical studies report on vision impairment after blunt frontal head trauma. A possible cause is damage to the optic nerve bundle within the optic canal due to microfractures of the anterior skull base leading to indirect traumatic optic neuropathy. A finite element study simulating impact forces on the paramedian forehead in different grades was initiated. The set-up consisted of a high-resolution skull model with about 740 000 elements, a blunt impactor and was solved in a transient time-dependent simulation. Individual bone material parameters were calculated for each volume element to increase realism. Results showed stress propagation from the frontal impact towards the optic foramen and the chiasm even at low-force fist-like impacts. Higher impacts produced stress patterns corresponding to typical fracture patterns of the anterior skull base including the optic canal. Transient simulation discerned two stress peaks equalling oscillation. It can be concluded that even comparatively low stresses and oscillation in the optic foramen may cause micro damage undiscerned by CT or MRI explaining consecutive vision loss. Higher impacts lead to typical comminuted fractures, which may affect the integrity of the optic canal. Finite element simulation can be effectively used in studying head trauma and its clinical consequences. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Does altered fractionation influence the risk of radiation-induced optic neuropathy?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhandare, Niranjan; Monroe, Alan T.; Morris, Christopher G.

2005-07-15

Purpose: To analyze the parameters that influence the risk of radiation-induced optic neuropathy (RION) after radiotherapy for head-and-neck tumors. Methods and Materials: Between 1964 and 2000, 273 patients with tumors of the nasopharynx, paranasal sinuses, nasal cavity, and hard palate adenoid cystic carcinomas were treated with curative intent and had radiation fields that included the optic nerves and/or chiasm. Patients were followed for at least 1 year after radiotherapy. Results: Radiation-induced optic neuropathy developed in 32 eyes of 24 patients (9%). The 5-year rates of freedom from RION according to the total dose and once- vs. twice-daily fractionation were asmore » follows: {<=}63 Gy once daily, 95%; {<=}63 Gy twice daily, 98%; >63 Gy once daily, 78%; and >63 Gy twice daily, 91%. Multivariate analysis revealed that the total dose affected the risk of RION (p = 0.0047), with patient age (p = 0.0909), once-daily vs. twice-daily fractionation (p = 0.0684), and overall treatment time (p = 0.0972) were marginally significant. The use of adjuvant chemotherapy did not significantly influence the likelihood of developing RION. Conclusion: The likelihood of developing RION is primarily influenced by the total dose. Hyperfractionation may reduce the risk of experiencing this complication.« less

BMP7 and SHH regulate Pax2 in mouse retinal astrocytes by relieving TLX repression.

PubMed

Sehgal, Rachna; Sheibani, Nader; Rhodes, Simon J; Belecky Adams, Teri L

2009-08-15

Pax2 is essential for development of the neural tube, urogenital system, optic vesicle, optic cup and optic tract. In the eye, Pax2 deficiency is associated with coloboma, a loss of astrocytes in the optic nerve and retina, and abnormal axonal pathfinding of the ganglion cell axons at the optic chiasm. Thus, appropriate expression of Pax2 is essential for astrocyte determination and differentiation. Although BMP7 and SHH have been shown to regulate Pax2 expression, the molecular mechanism by which this regulation occurs is not well understood. In this study, we determined that BMP7 and SHH activate Pax2 expression in mouse retinal astrocyte precursors in vitro. SHH appeared to play a dual role in Pax2 regulation; 1) SHH may regulate BMP7 expression, and 2) the SHH pathway cooperates with the BMP pathway to regulate Pax2 expression. BMP and SHH pathway members can interact separately or together with TLX, a repressor protein in the tailless transcription factor family. Here we show that the interaction of both pathways with TLX relieves the repression of Pax2 expression in mouse retinal astrocytes. Together these data reveal a new mechanism for the cooperative actions of signaling pathways in astrocyte determination and differentiation and suggest interactions of regulatory pathways that are applicable to other developmental programs.

Adjuvant or radical fractionated stereotactic radiotherapy for patients with pituitary functional and nonfunctional macroadenoma

PubMed Central

2011-01-01

Purpose To evaluate the efficacy and toxicity of stereotactic fractionated radiotherapy (SFRT) for patients with pituitary macroadenoma (PMA). Methods and Materials Between March 2000 and March 2009, 27 patients (male to female ratio, 1.25) with PMA underwent SFRT (median dose, 50.4 Gy). Mean age of the patients was 56.5 years (range, 20.3 - 77.4). In all but one patient, SFRT was administered for salvage treatment after surgical resection (transphenoidal resection in 23, transphenoidal resection followed by craniotomy in 2 and multiple transphenoidal resections in another patient). In 10 (37%) patients, the PMAs were functional (3 ACTH-secreting, 3 prolactinomas, 2 growth hormone-secreting and 2 multiple hormone-secretion). Three (11.1%) and 9 (33.3%) patients had PMA abutting and compressing the optic chiasm, respectively. Mean tumor volume was 2.9 ± 4.6 cm3. Eighteen (66.7%) patients had hypopituitarism prior to SFRT. The mean follow-up period after SFRT was 72.4 ± 37.2 months. Results Tumor size decreased for 6 (22.2%) patients and remained unchanged for 19 (70.4%) other patients. Two (7.4%) patients had tumor growth inside the prescribed treatment volume. The estimated 5-year tumor growth control was 95.5% after SFRT. Biochemical remission occurred in 3 (30%) patients with functional PMA. Two patients with normal anterior pituitary function before SFRT developed new deficits 25 and 65 months after treatment. The 5-year survival without new anterior pituitary deficit was thus 95.8%. Five patients with visual field defect had improved visual function and 1 patient with no visual defect prior to SFRT, but an optic chiasm abutting tumor, had a decline in visual function. The estimated 5-year vision and pituitary function preservation rates were 93.2% and 95.8%, respectively. Conclusions SFRT is a safe and effective treatment for patients with PMA, although longer follow-up is needed to evaluate long-term outcomes. In this study, approximately 1 patient with visual field defect out of two had an improved visual function. PMID:22152397

Early blindness and coma during intrathecal chemotherapy for meningeal carcinomatosis.

PubMed

Boogerd, W; Moffie, D; Smets, L A

1990-02-01

A 35-year-old woman was treated with intraventricular methotrexate (MTX) with a total dose of 70 mg followed by cytosine arabinoside (Ara-C) with a total dose of 80 mg for meningeal metastasis of breast carcinoma. Radiation therapy was not given. Despite a response of the meningeal tumor the patient developed in the third week of MTX treatment a progressive visual loss and loss of consciousness which worsened during subsequent Ara-C treatment and led to death within 3 weeks. Postmortem examination revealed only minimal neoplastic infiltration of the meninges. Multiple foci of axonal degeneration and demyelination were found in the optic nerves and chiasm, the superficial layers of the brainstem, and spinal cord and to some extent in other cranial nerves and spinal nerve roots. The possible causes of this previously unreported early complication are discussed.

TU-C-17A-05: Dose Domain Optimization of MLC Leaf Patterns for Highly Complicated 4Ï€ IMRT Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, D; Yu, V; Ruan, D

Purpose: Highly conformal non-coplanar 4π radiotherapy plans typically require more than 20 intensity-modulated fields to deliver. A novel method to calculate multileaf collimator (MLC) leaf patterns is introduced to maximize delivery efficiency, accuracy and plan quality. Methods: 4 GBM patients, with a prescription dose of 59.4 Gy or 60 Gy, were evaluated using the 4π algorithm using 20 beams. The MLC calculation utilized a least square minimization of the dose distribution, with an anisotropic total variation regularization term to encourage piecewise continuity in the fluence maps. Transforming the fluence to the dose domain required multiplying the fluence with a sparsemore » matrix. Exploiting this property made it feasible to solve the problem using CVX, a MATLAB-based convex modeling framework. The fluence was stratified into even step sizes, and the MLC segments, limited to 300, were calculated. The patients studied were replanned using Eclipse with the same beam angles. Results: Compared to the original 4π plan, the stratified 4π plan increased the maximum/mean dose for, in Gy, by 1.0/0.0 (brainstem), 0.5/0.2 (chiasm), 0.0/0.0 (spinal cord), 1.9/0.3 (L eye), 0.7/0.2 (R eye), 0.4/0.4 (L lens), 0.3/0.3 (R lens), 1.0/0.8 (L Optical Nerve), 0.5/0.3 (R Optical Nerve), 0.3/0.2 (L Cochlea), 0.1/0.1 (R Cochlea), 4.6/0.2 (brain), 2.4/0.1 (brain-PTV), 5.1/0.9 (PTV). Compared to Eclipse, which generated an average of 607 segments, the stratified plan reduced (−) or increased (+) the maximum/mean dose, in Gy, by −10.2/−4.1 (brainstem), −10.5/−8.9 (chiasm), +0.0/−0.1 (spinal cord), −4.9/−3.4 (L eye), −4.1/−2.5 (R eye), −2.8/−2.7 (L lens), −2.1/−1.9 (R lens), −7.6/−6.5 (L Optical Nerve), −8.9/−6.1 (R Optical Nerve), −1.3/−1.9 (L Cochlea), −1.8/−1.8 (R Cochlea), +1.7/−2.1 (brain), +3.2/−2.6 (brain-PTV), +1.8/+0.3 Gy (PTV. The stratified plan was also more homogeneous in the PTV. Conclusion: This novel solver can transform complicated fluence maps into significantly fewer deliverable MLC segments than the commercial system while achieving superior dosimetry. Funding support partially contributed by Varian.« less

Wolfram syndrome: a clinicopathologic correlation

PubMed Central

Merchant, Saumil N.; Adams, Joe C.; Joseph, Jeffrey T.

2009-01-01

Wolfram syndrome or DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness) is a neurodegenerative disorder characterized by diabetes mellitus and optic atrophy as well as diabetes insipidus and deafness in many cases. We report the post-mortem neuropathologic findings of a patient with Wolfram syndrome and correlate them with his clinical presentation. In the hypothalamus, neurons in the paraventricular and supraoptic nuclei were markedly decreased and minimal neurohypophyseal tissue remained in the pituitary. The pontine base and inferior olivary nucleus showed gross shrinkage and neuron loss, while the cerebellum was relatively unaffected. The visual system had moderate to marked loss of retinal ganglion neurons, commensurate loss of myelinated axons in the optic nerve, chiasm and tract, and neuron loss in the lateral geniculate nucleus but preservation of the primary visual cortex. The patient’s inner ear showed loss of the organ of Corti in the basal turn of the cochleae and mild focal atrophy of the stria vascularis. These findings correlated well with the patient’s high-frequency hearing loss. The pathologic findings correlated closely with the patient’s clinical symptoms and further support the concept of Wolfram syndrome as a neurodegenerative disorder. Our findings extend prior neuropathologic reports of Wolfram syndrome by providing contributions to our understanding of eye, inner ear and olivopontine pathology in this disease. PMID:19449020

The effects of rearing light level and duration differences on the optic nerve, brain, and associated structures in developing zebrafish larvae: a light and transmission electron microscope study.

PubMed

Chapman, George B; Tarboush, Rania; Connaughton, Victoria P

2012-03-01

The ultrastructure of the optic nerve, brain, and some associated structures of larval zebrafish, grown under three different light regimens were studied. Fish grown under cyclic light (control), constant dark (CD), and constant light (CL) were studied for 4 and 8 days postfertilization (dpf). We also studied the control and CD fish at 15 dpf. The brains of the control and CL fish were larger at 4 dpf than at 8 dpf. In all 4 dpf fish, the brain occupied the entire expanse between the two retinas and the optic nerve extended the shortest distance between the retina and the brain. The 15 dpf zebrafish had the smallest brain size. Groups of skeletal muscle cells associated with the optic nerves became visible in all older larvae. In the 15 dpf larvae, bulges and dilations in the optic nerve occurred as it reached the brain and optic chiasms occurred proximal to the brain. Electron microscopy yielded information about myelinated and unmyelinated axons in the optic nerve, the dimensions of neurotubules, neurofilaments, and myofilaments, including a unique variation in actin myofilaments, and a confirmation of reported myosin myofilament changes (but with dimensions). We also describe the ultrastructure of a sheath-like structure that is confluent over the optic nerve and the brain, which has not been described before in zebrafish. Also presented are images of associated fibroblasts, epithelial cells lining the mouth, cartilage plates, blood vessels, nerve bundles, and skeletal muscle cells, most of which have not been previously described in the literature. Copyright © 2012 Wiley Periodicals, Inc.

Distributed abnormalities of brain white matter architecture in patients with dominant optic atrophy and OPA1 mutations.

PubMed

Rocca, Maria A; Bianchi-Marzoli, Stefania; Messina, Roberta; Cascavilla, Maria Lucia; Zeviani, Massimo; Lamperti, Costanza; Milesi, Jacopo; Carta, Arturo; Cammarata, Gabriella; Leocani, Letizia; Lamantea, Eleonora; Bandello, Francesco; Comi, Giancarlo; Falini, Andrea; Filippi, Massimo

2015-05-01

Using advanced MRI techniques, we investigated the presence and topographical distribution of brain grey matter (GM) and white matter (WM) alterations in dominant optic atrophy (DOA) patients with genetically proven OPA1 mutation as well as their correlation with clinical and neuro-ophthalmologic findings. Nineteen DOA patients underwent neurological, neuro-ophthalmologic and brainstem auditory evoked potentials (BAEP) evaluations. Voxel-wise methods were applied to assess regional GM and WM abnormalities in patients compared to 20 healthy controls. Visual acuity was reduced in 16 patients. Six DOA patients (4 with missense mutations) had an abnormal I peripheral component (auditory nerve) at BAEP. Compared to controls, DOA patients had significant atrophy of the optic nerves (p < 0.0001). Voxel-based morphometry (VBM) analysis showed that, compared to controls, DOA patients had significant WM atrophy of the chiasm and optic tracts; whereas no areas of GM atrophy were found. Tract-based spatial statistics (TBSS) analysis showed that compared to controls, DOA patients had significantly lower mean diffusivity, axial and radial diffusivity in the WM of the cerebellum, brainstem, thalamus, fronto-occipital-temporal lobes, including the cingulum, corpus callosum, corticospinal tract and optic radiation bilaterally. No abnormalities of fractional anisotropy were detected. No correlations were found between volumetric and diffusivity abnormalities quantified with MRI and clinical and neuro-ophthalmologic measures of disease severity. Consistently with pathological studies, tissue loss in DOA patients is limited to anterior optic pathways reflecting retinal ganglion cell degeneration. Distributed abnormalities of diffusivity indexes might reflect abnormal intracellular mitochondrial morphology as well as alteration of protein levels due to OPA1 mutations.

Optical coherence tomography detects characteristic retinal nerve fiber layer thickness corresponding to band atrophy of the optic discs.

PubMed

Kanamori, Akiyasu; Nakamura, Makoto; Matsui, Noriko; Nagai, Azusa; Nakanishi, Yoriko; Kusuhara, Sentaro; Yamada, Yuko; Negi, Akira

2004-12-01

To analyze retinal nerve fiber layer (RNFL) thickness in eyes with band atrophy by use of optical coherence tomography (OCT) and to evaluate the ability of OCT to detect this characteristic pattern of RNFL loss. Cross-sectional, retrospective study. Thirty-four eyes of 18 patients with bitemporal hemianopia caused by optic chiasm compression by chiasmal tumors were studied. All eyes were divided into 3 groups according to visual field loss grading after Goldmann perimetry. Retinal nerve fiber layer thickness measurements with OCT. Retinal nerve fiber layer thickness around the optic disc was measured by OCT (3.4-mm diameter circle). Calculation of the changes in OCT parameters, including the horizontal (nasal + temporal quadrant RNFL thickness) and vertical values (superior + inferior quadrant RNFL thickness) was based on data from 160 normal eyes. Comparison between the 3 visual field grading groups was done with the analysis of variance test. The receiver operating characteristic (ROC) curve for the horizontal and vertical value were calculated, and the areas under the curve (AUC) were compared. Retinal nerve fiber layer thickness in eyes with band atrophy decreased in all OCT parameters. The reduction rate in average and temporal RNFL thickness and horizontal value was correlated with visual field grading. The AUC of horizontal value was 0.970+/-0.011, which was significantly different from AUC of vertical value (0.903+/-0.022). The degree of RNFL thickness reduction correlated with that of visual field defects. Optical coherence tomography was able to identify the characteristic pattern of RNFL loss in these eyes.

Seeing floaters - a case report and literature review of intraventricular migration of silicone oil tamponade material for retinal detachment.

PubMed

Potts, Matthew B; Wu, Alex C; Rusinak, David J; Kesavabhotla, Kartik; Jahromi, Babak S

2018-04-17

Intraocular injection of silicone oil is commonly performed during vitrectomy to tamponade the retina in place for treatment of retinal detachment. Although rare, this intravitreal silicone can migrate through the optic nerve and chiasm and enter the cerebral ventricles. Here we present a case report of a patient presenting with headache and intraventricular hyperdensities on computed tomography imaging raising concern for intraventricular hemorrhage. The intraventricular hyperdensities, however, were in a non-dependent location and moved to a new non-dependent location when a repeat imaging was performed with the patient in a prone position. We provide a literature review of this phenomenon and discuss the relevant CT and MRI findings. Intraocular silicone can rarely migrate into the cerebral ventricular system. Careful review of the clinical history and imaging findings can help distinguish this from other, more dangerous intracranial pathologies. Copyright © 2018. Published by Elsevier Inc.

Tablets at the bedside - iPad-based visual field test used in the diagnosis of Intrasellar Haemangiopericytoma: a case report.

PubMed

Nesaratnam, Nisha; Thomas, Peter B M; Kirollos, Ramez; Vingrys, Algis J; Kong, George Y X; Martin, Keith R

2017-04-24

In the assessment of a pituitary mass, objective visual field testing represents a valuable means of evaluating mass effect, and thus in deciding whether surgical management is warranted. In this vignette, we describe a 73 year-old lady who presented with a three-week history of frontal headache, and 'blurriness' in the left side of her vision, due to a WHO grade III anaplastic haemangiopericytoma compressing the optic chiasm. We report how timely investigations, including an iPad-based visual field test (Melbourne Rapid Field, (MRF)) conducted at the bedside aided swift and appropriate management of the patient. We envisage such a test having a role in assessing bed-bound patients in hospital where access to formal visual field testing is difficult, or indeed in rapid testing of visual fields at the bedside to screen for post-operative complications, such as haematoma.

Transsphenoidal pituitary resection with intraoperative MR guidance: preliminary results

NASA Astrophysics Data System (ADS)

Pergolizzi, Richard S., Jr.; Schwartz, Richard B.; Hsu, Liangge; Wong, Terence Z.; Black, Peter M.; Martin, Claudia; Jolesz, Ferenc A.

1999-05-01

The use of intraoperative MR image guidance has the potential to improve the precision, extent and safety of transsphenoidal pituitary resections. At Brigham and Women's Hospital, an open-bore configuration 0.5T MR system (SIGNA SP, GE Medical Systems, Milwaukee, WI) has been used to provide image guidance for nine transsphenoidal pituitary adenoma resections. The intraoperative MR system allowed the radiologist to direct the surgeon toward the sella turcica successfully while avoiding the cavernous sinus, optic chiasm and other sensitive structures. Imaging performed during the surgery monitored the extent of resection and allowed for removal of tumor beyond the surgeon's view in five cases. Dynamic MR imaging was used to distinguish residual tumor from normal gland and postoperative changes permitting more precise tumor localization. A heme-sensitive long TE gradient echo sequence was used to evaluate for the presence of hemorrhagic debris. All patients tolerated the procedure well without significant complications.

Thyrotropin-secreting pituitary adenoma in an adolescent boy: challenges in management.

PubMed

Kessler, Marion; David, Raphael; Pawelczak, Melissa; Hanono, Anat; Shah, Bina

2010-08-01

Thyrotropinomas tend to be aggressive, invasive tumors that are difficult to resect because of their marked fibrosis and their proximity to vital structures such as the optic chiasm. The latter characteristic also limits the use of radiation therapy. In the few cases reported of children younger than 18 years whose thyrotropinomas were treated surgically, the results were disappointing. We present here the case of a 16-year-old boy with a thyrotropin-secreting pituitary macroadenoma who underwent partial resection via a transsphenoidal approach and was left with significant residual tumor and continued hyperthyroidism. He subsequently received 4 years of long-acting release somatostatin therapy, during which he has remained euthyroid without requiring antithyroid medication. To our knowledge, this is thus far the longest duration of somatostatin therapy in the pediatric age group. This regimen also achieved a decrease in compression of the optic nerve and prevented further tumor growth. We review here the current literature on somatostatin analog treatment including molecular mechanisms and promising new treatment modalities, such as the heterodimerization of dopamine and somatostatin receptors. We conclude that this has been a useful adjuvant treatment for our adolescent patient.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoang Duc, Albert K., E-mail: albert.hoangduc.ucl@gmail.com; McClelland, Jamie; Modat, Marc

Purpose: The aim of this study was to assess whether clinically acceptable segmentations of organs at risk (OARs) in head and neck cancer can be obtained automatically and efficiently using the novel “similarity and truth estimation for propagated segmentations” (STEPS) compared to the traditional “simultaneous truth and performance level estimation” (STAPLE) algorithm. Methods: First, 6 OARs were contoured by 2 radiation oncologists in a dataset of 100 patients with head and neck cancer on planning computed tomography images. Each image in the dataset was then automatically segmented with STAPLE and STEPS using those manual contours. Dice similarity coefficient (DSC) wasmore » then used to compare the accuracy of these automatic methods. Second, in a blind experiment, three separate and distinct trained physicians graded manual and automatic segmentations into one of the following three grades: clinically acceptable as determined by universal delineation guidelines (grade A), reasonably acceptable for clinical practice upon manual editing (grade B), and not acceptable (grade C). Finally, STEPS segmentations graded B were selected and one of the physicians manually edited them to grade A. Editing time was recorded. Results: Significant improvements in DSC can be seen when using the STEPS algorithm on large structures such as the brainstem, spinal canal, and left/right parotid compared to the STAPLE algorithm (all p < 0.001). In addition, across all three trained physicians, manual and STEPS segmentation grades were not significantly different for the brainstem, spinal canal, parotid (right/left), and optic chiasm (all p > 0.100). In contrast, STEPS segmentation grades were lower for the eyes (p < 0.001). Across all OARs and all physicians, STEPS produced segmentations graded as well as manual contouring at a rate of 83%, giving a lower bound on this rate of 80% with 95% confidence. Reduction in manual interaction time was on average 61% and 93% when automatic segmentations did and did not, respectively, require manual editing. Conclusions: The STEPS algorithm showed better performance than the STAPLE algorithm in segmenting OARs for radiotherapy of the head and neck. It can automatically produce clinically acceptable segmentation of OARs, with results as relevant as manual contouring for the brainstem, spinal canal, the parotids (left/right), and optic chiasm. A substantial reduction in manual labor was achieved when using STEPS even when manual editing was necessary.« less

The extent of intrauterine growth restriction determines the severity of cerebral injury and neurobehavioural deficits in rodents.

PubMed

Ruff, Crystal A; Faulkner, Stuart D; Rumajogee, Prakasham; Beldick, Stephanie; Foltz, Warren; Corrigan, Jennifer; Basilious, Alfred; Jiang, Shangjun; Thiyagalingam, Shanojan; Yager, Jerome Y; Fehlings, Michael G

2017-01-01

Cerebral Palsy (CP) is the most common physical pediatric neurodevelopmental disorder and spastic diplegic injury is its most frequent subtype. CP results in substantial neuromotor and cognitive impairments that have significant socioeconomic impact. Despite this, its underlying pathophysiological mechanisms and etiology remain incompletely understood. Furthermore, there is a need for clinically relevant injury models, which a) reflect the heterogeneity of the condition and b) can be used to evaluate new translational therapies. To address these key knowledge gaps, we characterized a chronic placental insufficiency (PI) model, using bilateral uterine artery ligation (BUAL) of dams. This injury model results in intrauterine growth restriction (IUGR) in pups, and animals recapitulate the human phenotype both in terms of neurobehavioural and anatomical deficits. Effects of BUAL were studied using luxol fast blue (LFB)/hematoxylin & eosin (H&E) staining, immunohistochemistry, quantitative Magnetic Resonance Imaging (MRI), and Catwalk neurobehavioural tests. Neuroanatomical analysis revealed regional ventricular enlargement and corpus callosum thinning in IUGR animals, which was correlated with the extent of growth restriction. Olig2 staining revealed reductions in oligodendrocyte density in white and grey matter structures, including the corpus callosum, optic chiasm, and nucleus accumbens. The caudate nucleus, along with other brain structures such as the optic chiasm, internal capsule, septofimbrial and lateral septal nuclei, exhibited reduced size in animals with IUGR. The size of the pretectal nucleus was reduced only in moderately injured animals. MAG/NF200 staining demonstrated reduced myelination and axonal counts in the corpus callosum of IUGR animals. NeuN staining revealed changes in neuronal density in the hippocampus and in the thickness of hippocampal CA2 and CA3 regions. Diffusion weighted imaging (DWI) revealed regional white and grey matter changes at 3 weeks of age. Furthermore, neurobehavioural testing demonstrated neuromotor impairments in animals with IUGR in paw intensities, swing speed, relative print positions, and phase dispersions. We have characterized a rodent model of IUGR and have demonstrated that the neuroanatomical and neurobehavioural deficits mirror the severity of the IUGR injury. This model has the potential to be applied to examine the pathobiology of and potential therapeutic strategies for IUGR-related brain injury. Thus, this work has potential translational relevance for the study of CP.

The extent of intrauterine growth restriction determines the severity of cerebral injury and neurobehavioural deficits in rodents

PubMed Central

Rumajogee, Prakasham; Beldick, Stephanie; Foltz, Warren; Corrigan, Jennifer; Basilious, Alfred; Jiang, Shangjun; Thiyagalingam, Shanojan; Yager, Jerome Y.

2017-01-01

Background Cerebral Palsy (CP) is the most common physical pediatric neurodevelopmental disorder and spastic diplegic injury is its most frequent subtype. CP results in substantial neuromotor and cognitive impairments that have significant socioeconomic impact. Despite this, its underlying pathophysiological mechanisms and etiology remain incompletely understood. Furthermore, there is a need for clinically relevant injury models, which a) reflect the heterogeneity of the condition and b) can be used to evaluate new translational therapies. To address these key knowledge gaps, we characterized a chronic placental insufficiency (PI) model, using bilateral uterine artery ligation (BUAL) of dams. This injury model results in intrauterine growth restriction (IUGR) in pups, and animals recapitulate the human phenotype both in terms of neurobehavioural and anatomical deficits. Methods Effects of BUAL were studied using luxol fast blue (LFB)/hematoxylin & eosin (H&E) staining, immunohistochemistry, quantitative Magnetic Resonance Imaging (MRI), and Catwalk neurobehavioural tests. Results Neuroanatomical analysis revealed regional ventricular enlargement and corpus callosum thinning in IUGR animals, which was correlated with the extent of growth restriction. Olig2 staining revealed reductions in oligodendrocyte density in white and grey matter structures, including the corpus callosum, optic chiasm, and nucleus accumbens. The caudate nucleus, along with other brain structures such as the optic chiasm, internal capsule, septofimbrial and lateral septal nuclei, exhibited reduced size in animals with IUGR. The size of the pretectal nucleus was reduced only in moderately injured animals. MAG/NF200 staining demonstrated reduced myelination and axonal counts in the corpus callosum of IUGR animals. NeuN staining revealed changes in neuronal density in the hippocampus and in the thickness of hippocampal CA2 and CA3 regions. Diffusion weighted imaging (DWI) revealed regional white and grey matter changes at 3 weeks of age. Furthermore, neurobehavioural testing demonstrated neuromotor impairments in animals with IUGR in paw intensities, swing speed, relative print positions, and phase dispersions. Conclusions We have characterized a rodent model of IUGR and have demonstrated that the neuroanatomical and neurobehavioural deficits mirror the severity of the IUGR injury. This model has the potential to be applied to examine the pathobiology of and potential therapeutic strategies for IUGR-related brain injury. Thus, this work has potential translational relevance for the study of CP. PMID:28934247

Serial MRIs provide novel insight into natural history of optic pathway gliomas in patients with neurofibromatosis 1.

PubMed

Sellmer, Laura; Farschtschi, Said; Marangoni, Marco; Heran, Manraj K S; Birch, Patricia; Wenzel, Ralph; Mautner, Victor-Felix; Friedman, Jan M

2018-04-23

Optic pathway gliomas (OPGs) are present in 20% of children with neurofibromatosis 1 (NF1) but are less frequently observed in adults. Our goal was to determine the natural history of OPGs in children and adults with NF1. We analyzed the features of OPGs and other intracranial lesions on 1775 head MRI scans of 562 unselected adults and children with NF1 collected between 2003 and 2015. 52 (9.3%) of 562 patients in this study had an OPG diagnosed on their MRI. The median age at first scan with an OPG present was 12.7 years. Of the 52 OPG patients, the intraorbital optic nerves were affected in 29 patients (56%), the prechiasmatic optic nerves were affected in 32 patients (62%), the optic chiasm was affected in 17 patients (33%) and the optic radiations were affected in 19 patients (37%). 29 patients had two or more areas affected. One patient had a newly-appearing OPG, and 1 patient showed progression. The rate of progression over 5 years was 2.4% (95% CI: 0.4% to 16%). Four patients showed partial regression of their OPGs, but we observed no case of complete regression during this study. The rate of regression over 5 years was 8.9% (95% confidence intervals: 2.8% to 26%). We found the presence of UBOs and the presence of OPGs in individual patients to be highly associated (p = 0.0061). OPGs are more common in older adults with NF1 than previously thought. The occurrences of unidentified bright objects (UBOs) and asymptomatic OPGs are associated with each other. This suggests the possibility that OPGs that remain asymptomatic may differ pathogenically from those that become symptomatic.

Overexpression of Pax6 results in microphthalmia, retinal dysplasia and defective retinal ganglion cell axon guidance

PubMed Central

Manuel, Martine; Pratt, Thomas; Liu, Min; Jeffery, Glen; Price, David J

2008-01-01

Background The transcription factor Pax6 is expressed by many cell types in the developing eye. Eyes do not form in homozygous loss-of-function mouse mutants (Pax6Sey/Sey) and are abnormally small in Pax6Sey/+ mutants. Eyes are also abnormally small in PAX77 mice expressing multiple copies of human PAX6 in addition to endogenous Pax6; protein sequences are identical in the two species. The developmental events that lead to microphthalmia in PAX77 mice are not well-characterised, so it is not clear whether over- and under-expression of Pax6/PAX6 cause microphthalmia through similar mechanisms. Here, we examined the consequences of over-expression for the eye and its axonal connections. Results Eyes form in PAX77+/+ embryos but subsequently degenerate. At E12.5, we found no abnormalities in ocular morphology, retinal cell cycle parameters and the incidence of retinal cell death. From E14.5 on, we observed malformations of the optic disc. From E16.5 into postnatal life there is progressively more severe retinal dysplasia and microphthalmia. Analyses of patterns of gene expression indicated that PAX77+/+ retinae produce a normal range of cell types, including retinal ganglion cells (RGCs). At E14.5 and E16.5, quantitative RT-PCR with probes for a range of molecules associated with retinal development showed only one significant change: a slight reduction in levels of mRNA encoding the secreted morphogen Shh at E16.5. At E16.5, tract-tracing with carbocyanine dyes in PAX77+/+ embryos revealed errors in intraretinal navigation by RGC axons, a decrease in the number of RGC axons reaching the thalamus and an increase in the proportion of ipsilateral projections among those RGC axons that do reach the thalamus. A survey of embryos with different Pax6/PAX6 gene dosage (Pax6Sey/+, Pax6+/+, PAX77+ and PAX77+/+) showed that (1) the total number of RGC axons projected by the retina and (2) the proportions that are sorted into the ipsilateral and contralateral optic tracts at the optic chiasm vary differently with gene dosage. Increasing dosage increases the proportion projecting ipsilaterally regardless of the size of the total projection. Conclusion Pax6 overexpression does not obviously impair the initial formation of the eye and its major cell-types but prevents normal development of the retina from about E14.5, leading eventually to severe retinal degeneration in postnatal life. This sequence is different to that underlying microphthalmia in Pax6+/- heterozygotes, which is due primarily to defects in the initial stages of lens formation. Before the onset of severe retinal dysplasia, Pax6 overexpression causes defects of retinal axons, preventing their normal growth and navigation through the optic chiasm. PMID:18507827

Irregular chiasm-C-roughest, a member of the immunoglobulin superfamily, affects sense organ spacing on the Drosophila antenna by influencing the positioning of founder cells on the disc ectoderm.

PubMed

Venugopala Reddy, G; Reiter, C; Shanbhag, S; Fischbach, K F; Rodrigues, V

1999-10-01

We describe a role for Irregular chiasmC-roughest (IrreC-rst), an immunoglobulin (Ig) superfamily member, in patterning sense organs on the Drosophila antenna. IrreC-rst protein is initially expressed homogeneously on apical profiles of ectodermal cells in regions of the antennal disc. During specification of founder cells (FCs), the intracellular protein distribution changes and becomes concentrated in regions where specific intercellular contacts presumably occur. Loss of function mutations as well as misexpression of irreC-rst results in an altered arrangement of FCs within the disc compared to wildtype. Sense organ development occurs normally, although spacing is affected. Unlike its role in interommatidial spacing, irreC-rst does not affect apoptosis during antennal development. We propose that IrreC-rst affects the spatial relationship between sensory and ectodermal cells during FC delamination.

Boosting CNS axon regeneration by harnessing antagonistic effects of GSK3 activity.

PubMed

Leibinger, Marco; Andreadaki, Anastasia; Golla, Renate; Levin, Evgeny; Hilla, Alexander M; Diekmann, Heike; Fischer, Dietmar

2017-07-03

Implications of GSK3 activity for axon regeneration are often inconsistent, if not controversial. Sustained GSK3 activity in GSK3 S/A knock-in mice reportedly accelerates peripheral nerve regeneration via increased MAP1B phosphorylation and concomitantly reduces microtubule detyrosination. In contrast, the current study shows that lens injury-stimulated optic nerve regeneration was significantly compromised in these knock-in mice. Phosphorylation of MAP1B and CRMP2 was expectedly increased in retinal ganglion cell (RGC) axons upon enhanced GSK3 activity, but, surprisingly, no GSK3-mediated CRMP2 inhibition was detected in sciatic nerves, thus revealing a fundamental difference between central and peripheral axons. Conversely, genetic or shRNA-mediated conditional KO/knockdown of GSK3β reduced inhibitory phosphorylation of CRMP2 in RGCs and improved optic nerve regeneration. Accordingly, GSK3β KO-mediated neurite growth promotion and myelin disinhibition were abrogated by CRMP2 inhibition and largely mimicked in WT neurons upon expression of constitutively active CRMP2 (CRMP2 T/A ). These results underscore the prevalent requirement of active CRMP2 for optic nerve regeneration. Strikingly, expression of CRMP2 T/A in GSK3 S/A RGCs further boosted optic nerve regeneration, with axons reaching the optic chiasm within 3 wk. Thus, active GSK3 can also markedly promote axonal growth in central nerves if CRMP2 concurrently remains active. Similar to peripheral nerves, GSK3-mediated MAP1B phosphorylation/activation and the reduction of microtubule detyrosination contributed to this effect. Overall, these findings reconcile conflicting data on GSK3-mediated axon regeneration. In addition, the concept of complementary modulation of normally antagonistically targeted GSK3 substrates offers a therapeutically applicable approach to potentiate the regenerative outcome in the injured CNS.

Canine orbital meningiomas: a review of 22 cases.

PubMed

Mauldin, E.A.; Deehr, A.J.; Hertzke, D.; Dubielzig, R.R.

2000-01-01

Clinical and pathologic features of primary orbital meningiomas in the dog were reviewed. Twenty-two meningiomas, confined to the orbit, were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1981 to 1997. The dogs ranged in age from 3 to 17 years (mean = 9.2 years). The clinical presentation, reported in 20 cases, was indicative of a retrobulbar mass and included exophthalmos and orbital swelling (18/20), and papilledema or abnormalities of the posterior segment (7/20). Visual acuity was reported in 15 cases; of those, 12 dogs were blind in the affected eye. Follow-up information was obtained on 17 cases; six dogs developed local recurrence of the neoplasm. Two dogs with recurrent neoplasms simultaneously developed blindness in the opposite eye. Extension along the optic nerve to the optic chiasm was suspected. No metastasis was found at the time of the study. Enucleation with excisional biopsy was effective therapy to date in 11 cases (0.2-4.5 years follow-up time). All neoplasms were located within the vicinity of the optic nerve and, when sectioned through the optic nerve head, appeared to completely envelope the nerve. The neoplastic cells were arranged in tight whorls and bundles characteristic of meningiomas. Most tumors had islands of chondroid and osseous metaplasia (17/22). Ocular invasion was limited to small foci in the posterior choroid or optic nerve head of six dogs. Immunoperoxidase stains on 10 cases were positive for vimentin and S-100, but negative for cytokeratin. Electron microscopy revealed complex interdigitations between cell membranes and few desmosomal intercellular attachments. Primary orbital meningiomas have a characteristic histologic appearance and may recur locally after surgical excision.

Applying the algorithm "assessing quality using image registration circuits" (AQUIRC) to multi-atlas segmentation

NASA Astrophysics Data System (ADS)

Datteri, Ryan; Asman, Andrew J.; Landman, Bennett A.; Dawant, Benoit M.

2014-03-01

Multi-atlas registration-based segmentation is a popular technique in the medical imaging community, used to transform anatomical and functional information from a set of atlases onto a new patient that lacks this information. The accuracy of the projected information on the target image is dependent on the quality of the registrations between the atlas images and the target image. Recently, we have developed a technique called AQUIRC that aims at estimating the error of a non-rigid registration at the local level and was shown to correlate to error in a simulated case. Herein, we extend upon this work by applying AQUIRC to atlas selection at the local level across multiple structures in cases in which non-rigid registration is difficult. AQUIRC is applied to 6 structures, the brainstem, optic chiasm, left and right optic nerves, and the left and right eyes. We compare the results of AQUIRC to that of popular techniques, including Majority Vote, STAPLE, Non-Local STAPLE, and Locally-Weighted Vote. We show that AQUIRC can be used as a method to combine multiple segmentations and increase the accuracy of the projected information on a target image, and is comparable to cutting edge methods in the multi-atlas segmentation field.

Retinal projections in the bowfin, Amia calva: cytoarchitectonic and experimental analysis.

PubMed

Butler, A B; Northcutt, R G

1992-01-01

The retinofugal projections in the bowfin, a non-teleost actinopterygian, were studied by autoradiographic and horseradish peroxidase methods, and the cytoarchitecture of retinorecipient regions of the diencephalon was analyzed with serially sectioned, Bodian stained material. Nuclei were identified in the thalamus, the periventricular portion of the posterior tuberculum, synencephalon, and pretectum which are homologous to like-named nuclei in teleosts and other non-teleost actinopterygian fishes. Of particular note, a posterior pretectal nucleus and, possibly, a homologue of nucleus corticalis were found to be present in the pretectum. These nuclei have previously been identified only in teleosts. The posterior pretectal nucleus is relatively small in the bowfin, and the distribution of a small, versus a large, posterior pretectal nucleus in Teleostei and Halecomorphi suggests that this nucleus was small plesiomorphically. The pattern of retinofugal projections in the bowfin is similar to that in other non-teleost actinopterygian fishes and in teleosts in most regards. Contralaterally, the retina projects to nuclei in the dorsal and ventral thalamus, superficial and central pretectum, dorsal and ventral accessory optic nuclei, and to the optic tectum. Additionally, there are sparse projections to the suprachiasmatic nucleus in the preoptic area, the periventricular nucleus of the posterior tuberculum, and the dorsal and ventral periventricular pretectal nuclei. Ipsilateral projections are sparse and are derived from fibers which do not decussate in the optic chiasm. Undecussated ipsilateral retinal projections, as present in the bowfin, are a widely distributed character in vertebrates and appear to be plesiomorphic for vertebrates.

Visual System Involvement in Patients with Newly Diagnosed Parkinson Disease.

PubMed

Arrigo, Alessandro; Calamuneri, Alessandro; Milardi, Demetrio; Mormina, Enricomaria; Rania, Laura; Postorino, Elisa; Marino, Silvia; Di Lorenzo, Giuseppe; Anastasi, Giuseppe Pio; Ghilardi, Maria Felice; Aragona, Pasquale; Quartarone, Angelo; Gaeta, Michele

2017-12-01

Purpose To assess intracranial visual system changes of newly diagnosed Parkinson disease in drug-naïve patients. Materials and Methods Twenty patients with newly diagnosed Parkinson disease and 20 age-matched control subjects were recruited. Magnetic resonance (MR) imaging (T1-weighted and diffusion-weighted imaging) was performed with a 3-T MR imager. White matter changes were assessed by exploring a white matter diffusion profile by means of diffusion-tensor imaging-based parameters and constrained spherical deconvolution-based connectivity analysis and by means of white matter voxel-based morphometry (VBM). Alterations in occipital gray matter were investigated by means of gray matter VBM. Morphologic analysis of the optic chiasm was based on manual measurement of regions of interest. Statistical testing included analysis of variance, t tests, and permutation tests. Results In the patients with Parkinson disease, significant alterations were found in optic radiation connectivity distribution, with decreased lateral geniculate nucleus V2 density (F, -8.28; P < .05), a significant increase in optic radiation mean diffusivity (F, 7.5; P = .014), and a significant reduction in white matter concentration. VBM analysis also showed a significant reduction in visual cortical volumes (P < .05). Moreover, the chiasmatic area and volume were significantly reduced (P < .05). Conclusion The findings show that visual system alterations can be detected in early stages of Parkinson disease and that the entire intracranial visual system can be involved. © RSNA, 2017 Online supplemental material is available for this article.

Orbitopterional Approach for the Resection of a Suprasellar Craniopharyngioma: Adapting the Strategy to the Microsurgical and Pathologic Anatomy.

PubMed

Nguyen, Vincent; Basma, Jaafar; Klimo, Paul; Sorenson, Jeffrey; Michael, L Madison

2018-04-01

Objectives  To describe the orbitopterional approach for the resection of a suprasellar craniopharyngioma with emphasis on the microsurgical and pathological anatomy of such lesions. Design  After completing the orbitopterional craniotomy in one piece including a supraorbital ridge osteotomy, the Sylvian fissure was split in a distal to proximal direction. The ipsilateral optic nerve and internal carotid artery were identified. Establishing a corridor to the tumor through both the opticocarotid and optic cisterns allowed for a wide angle of attack. Using both corridors, a microsurgical gross total resection was achieved. A radical resection required transection of the stalk at the level of the hypothalamus. Photographs of the region are borrowed from Dr Rhoton's laboratory to illustrate the microsurgical anatomy. Understanding the cisternal and topographic relationships of the optic nerve, optic chiasm, and internal carotid artery is critical to achieving gross total resection while preserving normal anatomy. Participants  The surgery was performed by the senior author assisted by Dr. Jaafar Basma. The video was edited by Dr. Vincent Nguyen. Outcome Measures  Outcome was assessed with extent of resection and postoperative visual function. Results  A gross total resection of the tumor was achieved. The patient had resolution of her bitemporal hemianopsia. She had diabetes insipidus with normal anterior pituitary function. Conclusions  Understanding the microsurgical anatomy of the suprasellar region and the pathological anatomy of craniopharyngiomas is necessary to achieve a good resection of these tumors. The orbitopterional approach provides the appropriate access for such endeavor. The link to the video can be found at: https://youtu.be/Be6dtYIGqfs .

Endoscopic Endonasal Approach for Resection of a Pediatric Craniopharyngioma: Operative Video and Technical Nuances.

PubMed

Liu, James K; Eloy, Jean Anderson

2018-04-01

We present a pediatric case of a retrochiasmatic craniopharyngioma in the suprasellar region with third ventricular extension that was resected through a purely endoscopic endonasal approach (EEA) via the transplanum transtuberculum corridor. The patient is a 12-year-old boy who presented with progressive visual loss and panhypopituitarism. The EEA allows direct visualization of the undersurface of the optic chiasm and hypothalamus so that safe and meticulous tumor dissection can be performed to preserve these critical neurovascular structures. This video atlas demonstrates the operative technique and surgical nuances of the endoscopic skull base approach, microdissection of the tumor from the critical neurovascular structures, and multilayered reconstruction of the skull base defect with a nasoseptal flap. A gross total resection was achieved, and the patient was neurologically intact with improved visual acuity and visual fields. In summary, the EEA via the transplanum transtuberculum corridor is an important strategy in the armamentarium for surgical management of pediatric craniopharyngiomas. The link to the video can be found at: https://youtu.be/bmgO_PMRHPk .

Diffusion-weighted imaging of the sellar region: a comparison study of BLADE and single-shot echo planar imaging sequences.

PubMed

Yiping, Lu; Hui, Liu; Kun, Zhou; Daoying, Geng; Bo, Yin

2014-07-01

The purpose of this study is to compare BLADE diffusion-weighted imaging (DWI) with single-shot echo planar imaging (EPI) DWI on the aspects of feasibility of imaging the sellar region and image quality. A total of 3 healthy volunteers and 52 patients with suspected lesions in the sellar region were included in this prospective intra-individual study. All exams were performed at 3.0T with a BLADE DWI sequence and a standard single-shot EP-DWI sequence. Phantom measurements were performed to measure the objective signal-to-noise ratio (SNR). Two radiologists rated the image quality according to the visualisation of the internal carotid arteries, optic chiasm, pituitary stalk, pituitary gland and lesion, and the overall image quality. One radiologist measured lesion sizes for detecting their relationship with the image score. The SNR in BLADE DWI sequence showed no significant difference from the single-shot EPI sequence (P>0.05). All of the assessed regions received higher scores in BLADE DWI images than single-shot EP-DWI. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Tolerance of cranial nerves of the cavernous sinus to radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tishler, R.B.; Loeffler, J.S.; Alexander, E. III

1993-09-20

Stereotactic radiosurgery is becoming a more accepted treatment option for benign, deep seated intracranial lesions. However, little is known about the effects of large single fractions of radiation on cranial nerves. This study was undertaken to assess the effect of radiosurgery on the cranial nerves of the cavernous sinus. The authors examined the tolerance of cranial nerves (II-VI) following radiosurgery for 62 patients (42/62 with meningiomas) treated for lesions within or near the cavernous sinus. Twenty-nine patients were treated with a modified 6 MV linear accelerator (Joint Center for Radiation Therapy) and 33 were treated with the Gamma Knife (Universitymore » of Pittsburgh). Three-dimensional treatment plans were retrospectively reviewed and maximum doses were calculated for the cavernous sinus and the optic nerve and chiasm. Median follow-up was 19 months (range 3-49). New cranial neuropathies developed in 12 patients from 3-41 months following radiosurgery. Four of these complications involved injury to the optic system and 8 (3/8 transient) were the result of injury to the sensory or motor nerves of the cavernous sinus. There was no clear relationship between the maximum dose to the cavernous sinus and the development of complications for cranial nerves III-VI over the dose range used (1000-4000 cGy). For the optic apparatus, there was a significantly increased incidence of complications with dose. Four of 17 patients (24%) receiving greater than 800 cGy to any part of the optic apparatus developed visual complications compared with 0/35 who received less than 800 cGy (p = 0.009). Radiosurgery using tumor-controlling doses of up to 4000 cGy appears to be a relatively safe technique in treating lesions within or near the sensory and motor nerves (III-VI) of the cavernous sinus. The dose to the optic apparatus should be limited to under 800 cGy. 21 refs., 4 tabs.« less

Joint deep shape and appearance learning: application to optic pathway glioma segmentation

NASA Astrophysics Data System (ADS)

Mansoor, Awais; Li, Ien; Packer, Roger J.; Avery, Robert A.; Linguraru, Marius George

2017-03-01

Automated tissue characterization is one of the major applications of computer-aided diagnosis systems. Deep learning techniques have recently demonstrated impressive performance for the image patch-based tissue characterization. However, existing patch-based tissue classification techniques struggle to exploit the useful shape information. Local and global shape knowledge such as the regional boundary changes, diameter, and volumetrics can be useful in classifying the tissues especially in scenarios where the appearance signature does not provide significant classification information. In this work, we present a deep neural network-based method for the automated segmentation of the tumors referred to as optic pathway gliomas (OPG) located within the anterior visual pathway (AVP; optic nerve, chiasm or tracts) using joint shape and appearance learning. Voxel intensity values of commonly used MRI sequences are generally not indicative of OPG. To be considered an OPG, current clinical practice dictates that some portion of AVP must demonstrate shape enlargement. The method proposed in this work integrates multiple sequence magnetic resonance image (T1, T2, and FLAIR) along with local boundary changes to train a deep neural network. For training and evaluation purposes, we used a dataset of multiple sequence MRI obtained from 20 subjects (10 controls, 10 NF1+OPG). To our best knowledge, this is the first deep representation learning-based approach designed to merge shape and multi-channel appearance data for the glioma detection. In our experiments, mean misclassification errors of 2:39% and 0:48% were observed respectively for glioma and control patches extracted from the AVP. Moreover, an overall dice similarity coefficient of 0:87+/-0:13 (0:93+/-0:06 for healthy tissue, 0:78+/-0:18 for glioma tissue) demonstrates the potential of the proposed method in the accurate localization and early detection of OPG.

Total Human Eye Allotransplantation: Developing Surgical Protocols for Donor and Recipient Procedures

PubMed Central

Davidson, Edward H.; Wang, Eric W.; Yu, Jenny Y.; Fernandez-Miranda, Juan C.; Wang, Dawn J.; Richards, Nikisha; Miller, Maxine; Schuman, Joel S.; Washington, Kia M.

2017-01-01

Background Vascularized composite allotransplantation of the eye is an appealing, novel method for reconstruction of the nonfunctioning eye. The authors’ group has established the first orthotopic model for eye transplantation in the rat. With advancements in immunomodulation strategies together with new therapies in neuroregeneration, parallel development of human surgical protocols is vital for ensuring momentum toward eye transplantation in actual patients. Methods Cadaveric donor tissue harvest (n = 8) was performed with orbital exenteration, combined open craniotomy, and endonasal approach to ligate the ophthalmic artery with a cuff of paraclival internal carotid artery, for transection of the optic nerve at the optic chiasm and transection of cranial nerves III to VI and the superior ophthalmic vein at the cavernous sinus. Candidate recipient vessels (superficial temporal/internal maxillary/facial artery and superficial temporal/facial vein) were exposed. Vein grafts were required for all anastomoses. Donor tissue was secured in recipient orbits followed by sequential venous and arterial anastomoses and nerve coaptation. Pedicle lengths and calibers were measured. All steps were timed, photographed, video recorded, and critically analyzed after each operative session. Results The technical feasibility of cadaveric donor procurement and transplantation to cadaveric recipient was established. Mean measurements included optic nerve length (39 mm) and caliber (5 mm), donor artery length (33 mm) and caliber (3 mm), and superior ophthalmic vein length (15 mm) and caliber (0.5 mm). Recipient superficial temporal, internal maxillary artery, and facial artery calibers were 0.8, 2, and 2 mm, respectively; and superior temporal and facial vein calibers were 0.8 and 2.5 mm, respectively. Conclusion This surgical protocol serves as a benchmark for optimization of technique, large-animal model development, and ultimately potentiating the possibility of vision restoration transplantation surgery. PMID:27879599

Safety of multiple stereotactic radiosurgery treatments for multiple brain lesions.

PubMed

Hillard, Virany H; Shih, Lynn L; Chin, Shing; Moorthy, Chitti R; Benzil, Deborah L

2003-07-01

Stereotactic radiosurgery (SRS) is a widely used therapy for multiple brain lesions, and studies have clearly established the safety and efficacy of single-dose SRS. However, as patient survival has increased, the recurrence of tumors and the development of metastases to new sites within the brain have made it desirable to repeat treatments over time. The cumulative toxicity of multi-isocenter, multiple treatments has not been well defined. We have retrospectively studied 10 patients who received multiple SRS treatments for multiple brain lesions to assess the cumulative toxicity of these treatments. In a retrospective review of all patients treated with SRS using the X-knife (Radionics, Burlington, MA) at Westchester Medical Center/New York Medical College between December 1995 and December 2000, 10 patients were identified who received at least two treatments to at least 3 isocenters and had a minimum follow-up period of 6 months. Image fusion technique was used to determine cumulative doses to targeted lesions, whole brain and critical brain structures. Toxicities and complications were identified by chart and radiological review. The average of the maximum doses (cGy) to a point within the whole brain was 2402 (range 1617-3953); to the brainstem, 1059 (range 48-4126); to the right optic nerve, 223 (range 14-1012); to the left optic nerve, 159 (range 17-475); and to the optic chiasm, 219 (range 15-909). There were no focal neurological toxicities, including visual disturbances, cranial nerve palsies, or ataxia in any of the 10 patients. There were also no global toxicities, including cognitive decline or secondary tumors. Only one patient developed seizures that were difficult to control in association with radiation necrosis. Multiple SRS treatments at the cumulative doses used in our study are a safe therapy for patients with multiple brain lesions.

Spatio-temporal pattern of neuronal differentiation in the Drosophila visual system: A user’s guide to the dynamic morphology of the developing optic lobe

PubMed Central

Ngo, Kathy T.; Andrade, Ingrid; Hartenstein, Volker

2018-01-01

Visual information processing in animals with large image forming eyes is carried out in highly structured retinotopically ordered neuropils. Visual neuropils in Drosophila form the optic lobe, which consists of four serially arranged major subdivisions; the lamina, medulla, lobula and lobula plate; the latter three of these are further subdivided into multiple layers. The visual neuropils are formed by more than 100 different cell types, distributed and interconnected in an invariant highly regular pattern. This pattern relies on a protracted sequence of developmental steps, whereby different cell types are born at specific time points and nerve connections are formed in a tightly controlled sequence that has to be coordinated among the different visual neuropils. The developing fly visual system has become a highly regarded and widely studied paradigm to investigate the genetic mechanisms that control the formation of neural circuits. However, these studies are often made difficult by the complex and shifting patterns in which different types of neurons and their connections are distributed throughout development. In the present paper we have reconstructed the three-dimensional architecture of the Drosophila optic lobe from the early larva to the adult. Based on specific markers, we were able to distinguish the populations of progenitors of the four optic neuropils and map the neurons and their connections. Our paper presents sets of annotated confocal z-projections and animated 3D digital models of these structures for representative stages. The data reveal the temporally coordinated growth of the optic neuropils, and clarify how the position and orientation of the neuropils and interconnecting tracts (inner and outer optic chiasm) changes over time. Finally, we have analyzed the emergence of the discrete layers of the medulla and lobula complex using the same markers (DN-cadherin, Brp) employed to systematically explore the structure and development of the central brain neuropil. Our work will facilitate experimental studies of the molecular mechanisms regulating neuronal fate and connectivity in the fly visual system, which bears many fundamental similarities with the retina of vertebrates. PMID:28533086

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daly, Megan E.; Chen, Allen M.; Bucci, M. Kara

Purpose: To report the clinical outcome of patients treated with intensity-modulated radiation therapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses. Methods and Materials: Between 1998 and 2004, 36 patients with malignancies of the sinonasal region were treated with IMRT. Thirty-two patients (89%) were treated in the postoperative setting after gross total resection. Treatment plans were designed to provide a dose of 70 Gy to 95% or more of the gross tumor volume (GTV) and 60 Gy to 95% or more of the clinical tumor volume (CTV) while sparing neighboring critical structures including the optic chiasm, optic nerves,more » eyes, and brainstem. The primary sites were: 13 ethmoid sinus, 10 maxillary sinus, 7 nasal cavity, and 6 other. Histology was: 12 squamous cell, 7 esthesioneuroblastoma, 5 adenoid cystic, 5 undifferentiated, 5 adenocarcinoma, and 2 other. Median follow-up was 51 months among surviving patients (range, 9-82 months). Results: The 2-year and 5-year estimates of local control were 62% and 58%, respectively. One patient developed isolated distant metastasis, and none developed isolated regional failure. The 5-year rates of disease-free and overall survival were 55% and 45%, respectively. The incidence of ocular toxicity was minimal with no patients reporting decreased vision. Late complications included xerophthalmia (1 patient), lacrimal stenosis (1 patient), and cataract (1 patient). Conclusion: Although IMRT for malignancies of the sinonasal region does not appear to lead to significant improvements in disease control, the low incidence of complications is encouraging.« less

Preoperative Visualization of Cranial Nerves in Skull Base Tumor Surgery Using Diffusion Tensor Imaging Technology.

PubMed

Ma, Jun; Su, Shaobo; Yue, Shuyuan; Zhao, Yan; Li, Yonggang; Chen, Xiaochen; Ma, Hui

2016-01-01

To visualize cranial nerves (CNs) using diffusion tensor imaging (DTI) with special parameters. This study also involved the evaluation of preoperative estimates and intraoperative confirmation of the relationship between nerves and tumor by verifying the accuracy of visualization. 3T magnetic resonance imaging scans including 3D-FSPGR, FIESTA, and DTI were used to collect information from 18 patients with skull base tumor. DTI data were integrated into the 3D slicer for fiber tracking and overlapped anatomic images to determine course of nerves. 3D reconstruction of tumors was achieved to perform neighboring, encasing, and invading relationship between lesion and nerves. Optic pathway including the optic chiasm could be traced in cases of tuberculum sellae meningioma and hypophysoma (pituitary tumor). The oculomotor nerve, from the interpeduncular fossa out of the brain stem to supraorbital fissure, was clearly visible in parasellar meningioma cases. Meanwhile, cisternal parts of trigeminal nerve and abducens nerve, facial nerve were also imaged well in vestibular schwannomas and petroclival meningioma cases. The 3D-spatial relationship between CNs and skull base tumor estimated preoperatively by tumor modeling and tractography corresponded to the results determined during surgery. Supported by DTI and 3D slicer, preoperative 3D reconstruction of most CNs related to skull base tumor is feasible in pathological circumstances. We consider DTI Technology to be a useful tool for predicting the course and location of most CNs, and syntopy between them and skull base tumor.

Wolfram (DIDMOAD) syndrome: a multidisciplinary clinical study in nine Turkish patients and review of the literature.

PubMed

Simsek, E; Simsek, T; Tekgül, S; Hosal, S; Seyrantepe, V; Aktan, G

2003-01-01

To study Wolfram syndrome (WFS) with multidisciplinary consultations and compare the results with the literature. Nine patients fulfilled the ascertainment criteria of WFS (insulin-dependent diabetes mellitus and optic atrophy). All patients were evaluated by the departments of paediatrics, ophthalmology, audiology, urology and medical biology. The earliest manifestation of WFS was insulin-dependent diabetes mellitus (at a median age of 6.9 y), followed by optic atrophy (8.9 y), diabetes insipidus (10.2 y) and deafness (10.5 y). Short stature was found in five cases, delayed puberty in two cases and hypergonadotropic hypogonadism in one case. Audiography disclosed hearing loss at high frequency in all patients (100%), but only five patients had clinical subjective hearing problems. Intravenous pyelography revealed hydroureteronephrosis in eight patients. Urodynamics revealed a normal bladder in only one patient. Three patients had a low-capacity, low-compliance bladder, detrusor external sphincteric dyssynergia and emptying problem, while five had an atonic bladder. Ocular findings were optic atrophy, low visual acuity and colour vision defects. Visual field tests revealed concentric and/or peripheral diminution in five patients. Visual evoked potentials were abnormal (reduced amplitude to both flash and pattern stimulation) in seven patients. Cranial magnetic resonance imaging showed mild or moderate atrophy of the optic nerves, chiasm, cerebellum, basal ganglia and brainstem in six patients; there was a partially empty sella in one case. There was no evidence of mitochondrial tRNA(Leu) (UUR) A to G (nucleotide 3243) mutation. Wolfram syndrome should be evaluated in a multidisciplinary manner. Some specific and dynamic tests are necessary to make a more precise estimate of the prevalence and median age of the components of WFS. Short stature is a common feature in WFS. Hypogonadism may be hypogonadotropic or hypergonadotropic. Bladder dysfunction does not always present as a large atonic bladder in WFS. A low-capacity, high-pressure bladder with sphincteric dyssynergia is also common.

Frequency of brain MRI abnormalities in neuromyelitis optica spectrum disorder at presentation: A cohort of Latin American patients.

PubMed

Carnero Contentti, Edgar; Daccach Marques, Vanessa; Soto de Castillo, Ibis; Tkachuk, Veronica; Antunes Barreira, Amilton; Armas, Elizabeth; Chiganer, Edson; de Aquino Cruz, Camila; Di Pace, José Luis; Hryb, Javier Pablo; Lavigne Moreira, Carolina; Lessa, Carmen; Molina, Omaira; Perassolo, Monica; Soto, Arnoldo; Caride, Alejandro

2018-01-01

Brain magnetic resonance imaging (BMRI) lesions were classically not reported in neuromyelitis optica (NMO). However, BMRI lesions are not uncommon in NMO spectrum disorder (NMOSD) patients. To report BMRI characteristic abnormalities (location and configuration) in NMOSD patients at presentation. Medical records and BMRI characteristics of 79 patients with NMOSD (during the first documented attack) in Argentina, Brazil and Venezuela were reviewed retrospectively. BMRI abnormalities were observed in 81.02% of NMOSD patients at presentation. Forty-two patients (53.1%) showed typical-NMOSD abnormalities. We found BMRI abnormalities at presentation in the brainstem/cerebellum (n = 26; 32.9%), optic chiasm (n = 16; 20.2%), area postrema (n = 13; 16.4%), thalamus/hypothalamus (n = 11; 13.9%), corpus callosum (n = 11; 13.9%), periependymal-third ventricle (n = 9; 11.3%), corticospinal tract (n = 7; 8.8%), hemispheric white matter (n = 1; 1.2%) and nonspecific areas (n = 49; 62.03%). Asymptomatic BMRI lesions were more common. The frequency of brain MRI abnormalities did not differ between patients who were positive and negative for aquaporin 4 antibodies at presentation. Typical brain MRI abnormalities are frequent in NMOSD at disease onset. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of radiosurgery in craniopharyngiomas: a preliminary report.

PubMed

Amendola, Beatriz E; Wolf, Aizik; Coy, Sammie R; Amendola, Marco A

2003-08-01

The purpose of this retrospective review is to evaluate our experience using radiosurgery in the management of craniopharyngiomas. Fourteen patients, 6 males and 8 females, ages ranging from 3 to 44 years of age, were treated with radiosurgery from February 1994 through December 2000 for primary or recurrent craniopharyngioma. There were two adults and 12 children. All patients were treated with the Leksell Gamma units Model U or C. The mean minimum dose was 14 Gy ranging from 11 to 20 Gy and the mean maximum dose was 29 Gy ranging from 24 to 40 Gy. Volume of treatment ranged from 0.1 to 26.5 cm(3). The dose to critical structures was below 8 Gy to the optic chiasm and below 14 Gy to the brain stem. One of the 14 patients had previous conventional radiation therapy. All patients are alive and with out evidence of recurrent disease 6-86 months after treatment. Only two patients required retreatment. Although craniopharyngioma is a benign tumor, its location makes even advanced microsurgical techniques difficult to perform. Radiosurgery obviates the shortcomings of surgical resection near the hypothalamic-pituitary axis without the morbidity of open surgery. Copyright 2003 Wiley-Liss, Inc.

Epidemiology, clinical presentation and diagnosis of non-functioning pituitary adenomas.

PubMed

Ntali, Georgia; Wass, John A

2018-04-01

Non-functioning pituitary adenomas (NFPAs) are benign pituitary neoplasms that do not cause a hormonal hypersecretory syndrome. An improved understanding of their epidemiology, clinical presentation and diagnosis is needed. A literature review was performed using Pubmed to identify research reports and clinical case series on NFPAs. They account for 14-54% of pituitary adenomas and have a prevalence of 7-41.3/100,000 population. Their standardized incidence rate is 0.65-2.34/100,000 and the peak occurence is from the fourth to the eighth decade. The clinical spectrum of NFPAs varies from being completely asymptomatic to causing significant hypothalamic/pituitary dysfunction and visual field compromise due to their large size. Most patients present with symptoms of mass effect, such as headaches, visual field defects, ophthalmoplegias, and hypopituitarism but also hyperprolactinaemia due to pituitary stalk deviation and less frequently pituitary apoplexy. Non-functioning pituitary incidentalomas are found on brain imaging performed for an unrelated reason. Diagnostic approach includes magnetic resonance imaging of the sellar region, laboratory evaluations, screening for hormone hypersecretion and for hypopituitarism, and a visual field examination if the lesion abuts the optic nerves or chiasm. This article reviews the epidemiology, clinical behaviour and diagnostic approach of non-functioning pituitary adenomas.

The use of hypofractionated intensity-modulated irradiation in the treatment of glioblastoma multiforme: preliminary results of a prospective trial.

PubMed

Sultanem, Khalil; Patrocinio, Horacio; Lambert, Christine; Corns, Robert; Leblanc, Richard; Parker, William; Shenouda, George; Souhami, Luis

2004-01-01

Despite major advances in treatment modalities, the prognosis of patients with glioblastoma multiforme (GBM) remains poor. Exploring hypofractionated regimens to replace the standard 6-week radiotherapy schedule is an attractive strategy as an attempt to prevent accelerated tumor cell repopulation. There is equally interest in dose escalation to the gross tumor volume where the majority of failures occur. We report our preliminary results using hypofractionated intensity-modulated accelerated radiotherapy regimen in the treatment of patients with GBM. Between July 1998 and December 2001, 25 patients with histologically proven diagnosis of GBM, Karnofsky performance status > or =60, and a postoperative tumor volume < or =110 cm3 were treated with a hypofractionated accelerated course of radiotherapy. The gross tumor volume (GTV) was defined as the contrast-enhancing lesion on the postoperative MRI T1-weighted images with the latter fused with computed tomography images for treatment planning. The planning target volume was defined as GTV + 1.5-cm margin. Using forward-planning intensity modulation (step-and-shoot technique), 60 Gy in 20 daily fractions of 3 Gy each were given to the GTV, whereas the planning target volume received a minimum of 40 Gy in 20 fractions of 2 Gy each at its periphery. Treatments were delivered over a 4-week period using 5 daily fractions per week. Dose was prescribed at the isocenter (ICRU point). Three beam angles were used in all of the cases. Treatments were well tolerated. Acute toxicity was limited to increased brain edema during radiotherapy in 2 patients who were on tapering doses of corticosteroids. This was corrected by increasing the steroid dose. At a median follow-up of 8.8 months, no late toxicity was observed. One patient experienced visual loss at 9 months after completion of treatment. MRI suggested nonspecific changes to the optic chiasm. On review of the treatment plan, the total dose to the optic chiasm was confirmed to be equal to or less than 40 Gy in 20 fractions. When Radiation Therapy Oncology Group recursive partitioning analysis was used, 10 patients were class III-IV, and 15 patients were class V-VI. To date, 21 patients have had clinical and/or radiologic evidence of disease progression, and 16 patients have died. The median survival was 9.5 months (range: 2.8-22.9 months), the 1-year survival rate was 40%, and the median progression-free survival was 5.2 months (range: 1.9-12.8 months). This hypofractionated accelerated irradiation schedule using forward planning (step-and-shoot) hypofractionated, intensity-modulated accelerated radiotherapy is feasible and seems to be a safe treatment for patients with GBM. A 2-week reduction in the treatment time may be of valuable benefit for this group of patients. However, despite this accelerated regimen, no survival advantage has been observed.

Whole-brain hippocampal sparing radiation therapy: Volume-modulated arc therapy vs intensity-modulated radiation therapy case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Katrina, E-mail: Trinabena23@gmail.com; Lenards, Nishele; Holson, Janice

The hippocampus is responsible for memory and cognitive function. An ongoing phase II clinical trial suggests that sparing dose to the hippocampus during whole-brain radiation therapy can help preserve a patient's neurocognitive function. Progressive research and advancements in treatment techniques have made treatment planning more sophisticated but beneficial for patients undergoing treatment. The aim of this study is to evaluate and compare hippocampal sparing whole-brain (HS-WB) radiation therapy treatment planning techniques using volume-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT). We randomly selected 3 patients to compare different treatment techniques that could be used for reducing dose to themore » hippocampal region. We created 2 treatment plans, a VMAT and an IMRT, from each patient's data set and planned on the Eclipse 11.0 treatment planning system (TPS). A total of 6 plans (3 IMRT and 3 VMAT) were created and evaluated for this case study. The physician contoured the hippocampus as per the Radiation Therapy Oncology Group (RTOG) 0933 protocol atlas. The organs at risk (OR) were contoured and evaluated for the plan comparison, which included the spinal cord, optic chiasm, the right and left eyes, lenses, and optic nerves. Both treatment plans produced adequate coverage on the planning target volume (PTV) while significantly reducing dose to the hippocampal region. The VMAT treatment plans produced a more homogenous dose distribution throughout the PTV while decreasing the maximum point dose to the target. However, both treatment techniques demonstrated hippocampal sparing when irradiating the whole brain.« less

Neonatal monosodium glutamate treatment counteracts circadian arrhythmicity induced by phase shifts of the light-dark cycle in female and male Siberian hamsters

PubMed Central

Prendergast, Brian J.; Onishi, Kenneth G.; Zucker, Irving

2013-01-01

Studies of rats and voles suggest that distinct pathways emanating from the anterior hypothalamic-retrochiasmatic area and the mediobasal hypothalamic arcuate nucleus independently generate ultradian rhythms (URs) in hormone secretion and behavior. We evaluated the hypothesis that destruction of arcuate nucleus (ARC) neurons, in concert with dampening of suprachiasmatic nucleus (SCN) circadian rhythmicity, would compromise the generation of ultradian rhythms (URs) of locomotor activity. Siberian hamsters of both sexes treated neonatally with monosodium glutamate (MSG) that destroys ARC neurons were subjected in adulthood to a circadian disrupting phase-shift protocol (DPS) that produces SCN arrhythmia. MSG treatments induced hypogonadism and obesity, and markedly reduced the size of the optic chiasm and primary optic tracts. MSG-treated hamsters exhibited normal entrainment to the light-dark cycle, but MSG treatment counteracted the circadian arrhythmicity induced by the DPS protocol: only 6% of MSG-treated hamsters exhibited circadian arrhythmia, whereas 50% of control hamsters were circadian disrupted. In MSG-treated hamsters that retained circadian rhythmicity after DPS treatment, quantitative parameters of URs appeared normal, but in the 2 MSG-treated hamsters that became circadian arrhythmic after DPS, both dark-phase and light-phase URs were abolished. Although preliminary, these data are consistent with reports in voles suggesting that the combined disruption of SCN and ARC function impairs the expression of behavioral URs. The data also suggest that light thresholds for entrainment of circadian rhythms may be lower than those required to disrupt circadian organization. PMID:23701725

Extraretinal induced visual sensations during IMRT of the brain.

PubMed

Wilhelm-Buchstab, Timo; Buchstab, Barbara Myrthe; Leitzen, Christina; Garbe, Stephan; Müdder, Thomas; Oberste-Beulmann, Susanne; Sprinkart, Alois Martin; Simon, Birgit; Nelles, Michael; Block, Wolfgang; Schoroth, Felix; Schild, Hans Heinz; Schüller, Heinrich

2015-01-01

We observed visual sensations (VSs) in patients undergoing intensity modulated radiotherapy (IMRT) of the brain without the beam passing through ocular structures. We analyzed this phenomenon especially with regards to reproducibility, and origin. Analyzed were ten consecutive patients (aged 41-71 years) with glioblastoma multiforme who received pulsed IMRT (total dose 60Gy) with helical tomotherapy (TT). A megavolt-CT (MVCT) was performed daily before treatment. VSs were reported and recorded using a triggered event recorder. The frequency of VSs was calculated and VSs were correlated with beam direction and couch position. Subjective patient perception was plotted on an 8x8 visual field (VF) matrix. Distance to the orbital roof (OR) from the first beam causing a VS was calculated from the Dicom radiation therapy data and MVCT data. During 175 treatment sessions (average 17.5 per patient) 5959 VSs were recorded and analyzed. VSs occurred only during the treatment session not during the MVCTs. Plotting events over time revealed patient-specific patterns. The average cranio-caudad extension of VS-inducing area was 63.4mm (range 43.24-92.1mm). The maximum distance between the first VS and the OR was 56.1mm so that direct interaction with the retina is unlikely. Data on subjective visual perception showed that VSs occurred mainly in the upper right and left quadrants of the VF. Within the visual pathways the highest probability for origin of VSs was seen in the optic chiasm and the optic tract (22%). There is clear evidence that interaction of photon irradiation with neuronal structures distant from the eye can lead to VSs.

Memory and anatomical change in severe non missile traumatic brain injury: ∼1 vs. ∼8 years follow-up.

PubMed

Tomaiuolo, Francesco; Bivona, Umberto; Lerch, Jason P; Di Paola, Margherita; Carlesimo, Giovanni A; Ciurli, Paola; Matteis, Mariella; Cecchetti, Luca; Forcina, Antonio; Silvestro, Daniela; Azicnuda, Eva; Sabatini, Umberto; Di Giacomo, Dina; Caltagirone, Carlo; Petrides, Michael; Formisano, Rita

2012-03-10

In previous studies, we investigated a group of subjects who had suffered from a severe non missile traumatic brain injury (nmTBI) without macroscopic focal lesions and we found brain atrophy involving the hippocampus, fornix, corpus callosum, optic chiasm, and optic radiations. Memory test scores correlated mainly with fornix volumes [37,38]. In the present study, we re-examined 11 of these nmTBI subjects approximately 8 yr later. High-spatial resolution T1 weighted magnetic resonance images of the brain (1mm(3)) and standardised memory tests were performed once more in order to compare brain morphology and memory performance originally assessed 3-13 months after head injury (first study) and after 8-10 yr (present study). An overall improvement of memory test performance was demonstrated in the latest assessment, indicating that cognitive recovery in severe nmTBI subjects had not been completed within 3-13 months post-injury. It is notable that the volumes of the fornix and the hippocampus were reduced significantly from normal controls, but these volumes do not differ appreciatively between nmTBI subjects at first (after ∼1 yr) and at second (after ∼8 yr) scans. On the contrary, a clear reduction in the volume of the corpus callosus can be observed after ∼1 yr and a further significant reduction is evident after ∼8 yr, indicating that the neural degeneration in severe nmTBI continues long after the head trauma and relates to specific structures and not to the overall brain. Copyright © 2012 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munbodh, R; Ding, X; Yin, L

Purpose: To identify indicators of Late Grade 3 (LG3) toxicity, late vision and hearing changes in patients treated for primary brain tumors with photon (XRT) or proton radiotherapy (PRT). Methods: We retrospectively reviewed 102 patients who received brain XRT or PRT to doses of 54 or 59.6 Gy in daily fractions of 1.8–2 Gy. Of the 80 patients (34 XRT, 39 PRT and 7 both modalities) reviewed for indicators of LG3 toxicity, 25 developed LG3 toxicity 90 to 500 days after radiotherapy completion. 55 patients had less than LG3 toxicity > 500 days after treatment. In that time, late visionmore » and hearing changes were seen in 44 of 75 and 25 of 78 patients, respectively. The correlation between late toxicity and prescription dose, planning target volume (PTV) size, and doses to the brainstem, brain, optic chiasm, optic nerves, eyes and cochlea was evaluated. A two-tailed Fisher's exact test and Wilcoxon rank sum test were used for the statistical analysis for XRT, PRT and all patients combined. Results: Exceeding the 54 Gy-5% dose-volume brainstem constraint, but not the optic structure constraints, was significantly correlated (p < 0.05) with late vision changes in all three groups. Exceeding maximum and mean cochlear doses of 45 and 30 Gy, respectively, was a significant indicator of hearing changes (p < 0.05) in PRT patients and all patients combined. In a sub-group of 52 patients in whom the brain was contoured, the absolute brain volume receiving ≤ 50 Gy and > 60 Gy was significantly larger in patients with LG3 toxicity for all patients combined (p < 0.05). Prescription dose, brainstem dose and PTV volume were not correlated to LG3 toxicity. Conclusion: Our results indicate the importance of minimizing the brain volume irradiated, and brainstem and cochlea doses to reduce the risk of late toxicities following brain radiotherapy.« less

The Primary Visual Cortex Is Differentially Modulated by Stimulus-Driven and Top-Down Attention

PubMed Central

Bekisz, Marek; Bogdan, Wojciech; Ghazaryan, Anaida; Waleszczyk, Wioletta J.; Kublik, Ewa; Wróbel, Andrzej

2016-01-01

Selective attention can be focused either volitionally, by top-down signals derived from task demands, or automatically, by bottom-up signals from salient stimuli. Because the brain mechanisms that underlie these two attention processes are poorly understood, we recorded local field potentials (LFPs) from primary visual cortical areas of cats as they performed stimulus-driven and anticipatory discrimination tasks. Consistent with our previous observations, in both tasks, we found enhanced beta activity, which we have postulated may serve as an attention carrier. We characterized the functional organization of task-related beta activity by (i) cortical responses (EPs) evoked by electrical stimulation of the optic chiasm and (ii) intracortical LFP correlations. During the anticipatory task, peripheral stimulation that was preceded by high-amplitude beta oscillations evoked large-amplitude EPs compared with EPs that followed low-amplitude beta. In contrast, during the stimulus-driven task, cortical EPs preceded by high-amplitude beta oscillations were, on average, smaller than those preceded by low-amplitude beta. Analysis of the correlations between the different recording sites revealed that beta activation maps were heterogeneous during the bottom-up task and homogeneous for the top-down task. We conclude that bottom-up attention activates cortical visual areas in a mosaic-like pattern, whereas top-down attentional modulation results in spatially homogeneous excitation. PMID:26730705

Facilitation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor transmission in the suprachiasmatic nucleus by aniracetam enhances photic responses of the biological clock in rodents.

PubMed

Moriya, Takahiro; Ikeda, Masayuki; Teshima, Koji; Hara, Reiko; Kuriyama, Koji; Yoshioka, Tohru; Allen, Charles N; Shibata, Shigenobu

2003-05-01

This study was designed to test whether the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor-facilitating drug, aniracetam, could potentiate photic responses of the biological clock in the suprachiasmatic nucleus (SCN) of rodents. Using the whole-cell patch technique, we first demonstrated that AMPA currents elicited by either local AMPA application or optic chiasm stimulation were augmented by aniracetam in the neurons of the SCN. The AMPA application-elicited increase of intracellular Ca2+ concentration in SCN slices was also enhanced by aniracetam treatment. The systemic injection of aniracetam dose-dependently (10-100 mg/kg) potentiated the phase delay in behavioral rhythm induced by brief light exposure of low intensity (3 lux) but not high intensity (10 or 60 lux) during early subjective night. Under the blockade of NMDA receptors by (+) MK801, aniracetam failed to potentiate a light (3 lux)-induced phase delay in behavioral rhythm. Aniracetam increased the photic induction of c-Fos protein in the SCN that was elicited by low intensity light exposure (3 lux). These results suggest that AMPA receptor-mediated responses facilitated by aniracetam can explain enhanced photic responses of the biological clock in the SCN of rodents.

Meningioma Causing Visual Impairment: Outcomes and Toxicity After Intensity Modulated Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maclean, Jillian, E-mail: jillian.maclean@uclh.nhs.uk; Fersht, Naomi; Bremner, Fion

2013-03-15

Purpose: To evaluate ophthalmologic outcomes and toxicity of intensity modulated radiation therapy (IMRT) in patients with meningiomas causing visual deficits. Methods and Materials: A prospective observational study with formal ophthalmologic and clinical assessment of 30 consecutive cases of meningioma affecting vision treated with IMRT from 2007 to 2011. Prescriptions were 50.4 Gy to mean target dose in 28 daily fractions. The median follow-up time was 28 months. Twenty-six meningiomas affected the anterior visual pathway (including 3 optic nerve sheath meningiomas); 4 were posterior to the chiasm. Results: Vision improved objectively in 12 patients (40%). Improvements were in visual field (5/16more » patients), color vision (4/9 patients), acuity (1/15 patients), extraocular movements (3/11 patients), ptosis (1/5 patients), and proptosis (2/6 patients). No predictors of clinical response were found. Two patients had minor reductions in tumor dimensions on magnetic resonance imaging, 1 patient had radiological progression, and the other patients were stable. One patient experienced grade 2 keratitis, 1 patient had a minor visual field loss, and 5 patients had grade 1 dry eye. Conclusion: IMRT is an effective method for treating meningiomas causing ophthalmologic deficits, and toxicity is minimal. Thorough ophthalmologic assessment is important because clinical responses often occur in the absence of radiological change.« less

Olfactory groove meningiomas.

PubMed

Hentschel, Stephen J; DeMonte, Franco

2003-06-15

Olfactory groove meningiomas (OGMs) arise over the cribriform plate and may reach very large sizes prior to presentation. They can be differentiated from tuberculum sellae meningiomas because OGMs arise more anterior in the skull base and displace the optic nerve and chiasm inferiorly rather than superiorly. The authors searched the neurosurgery database at the M. D. Anderson Cancer Center for cases of OGM treated between 1993 and 2003. The records of these patients were then reviewed retrospectively for details regarding clinical presentation, imaging findings, surgical results and complications, and follow-up status. Thirteen patients, (12 women and one man, mean age 56 years) harbored OGMs (mean size 5.7 cm). All patients underwent bifrontal craniotomies and biorbital osteotomies. There were 11 complete resections (including the hyperostotic bone and dura of the cribriform plate and any extension into the ethmoid sinuses) and two subtotal resections with minimal residual tumor left in patients with recurrent lesions. No complication directly due to the surgery occurred in any patient. There were no recurrences in a mean follow-up period of 2 years (range 0-5 years). With current microsurgical techniques, the results of OGM resection are excellent, with a high rate of total resection and a low incidence of complications. All hyperostotic bone should be removed with the dura of the anterior skull base to minimize the risk of recurrence.

Changes in brain morphology in albinism reflect reduced visual acuity.

PubMed

Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

2014-07-01

Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. Copyright © 2012 Elsevier Ltd. All rights reserved.

Hypertriglyceridemia-induced pancreatitis: A case-based review

PubMed Central

Gan, S Ian; Edwards, Alun L; Symonds, Christopher J; Beck, Paul L

2006-01-01

Hypertriglyceridemia is an established cause of pancreatitis. In a case-based approach, we present a review of hypertriglyceridemia and how it can cause pancreatitis. We outline how to investigate and manage such patients. A 35 year old man presented to the emergency department with abdominal pain and biochemical evidence of acute pancreatitis. There was no history of alcohol consumption and biliary imaging was normal. The only relevant past medical history was that of mild hyperlipidemia, treated with diet alone. Physical exam revealed epigastric tenderness, right lateral rectus palsy, lipemia retinalis, bitemporal hemianopsia and a delay in the relaxation phase of his ankle reflexes. Subsequent laboratory investigation revealed marked hypertriglyceridemia and panhypopituarism. An enhanced CT scan of the head revealed a large suprasellar mass impinging on the optic chiasm and hypothalamus. The patient was treated supportively; thyroid replacement and lipid lowering agents were started. He underwent a successful resection of a craniopharyngioma. Post-operatively, the patient did well on hormone replacement therapy. He has had no further attacks of pancreatitis. This case highlights many of the factors involved in the regulation of triglyceride metabolism. We review the common causes of hypertriglyceridemia and the proposed mechanisms resulting in pancreatitis. The incidence and management of hypertriglyceridemia-induced pancreatitis are also discussed. PMID:17131487

Is it sufficient to repeat LINEAR accelerator stereotactic radiosurgery in choroidal melanoma?

PubMed

Furdova, A; Horkovicova, K; Justusova, P; Sramka, M

One day session LINAC based stereotactic radiosurgery (SRS) at LINAC accelerator is a method of "conservative" attitude to treat the intraocular malignant uveal melanoma. We used model Clinac 600 C/D Varian (system Aria, planning system Corvus version 6.2 verification IMRT OmniPro) with 6 MeV X by rigid immobilization of the eye to the Leibinger frame. The stereotactic treatment planning after fusion of CT and MRI was optimized according to the critical structures (lens, optic nerve, also lens and optic nerve at the contralateral side, chiasm). The first plan was compared and the best plan was applied for therapy at C LINAC accelerator. The planned therapeutic dose was 35.0 Gy by 99 % of DVH (dose volume histogram). In our clinical study in the group of 125 patients with posterior uveal melanoma treated with SRS, in 2 patients (1.6 %) was repeated SRS indicated. Patient age of the whole group ranged from 25 to 81 years with a median of 54 TD was 35.0 Gy. In 2 patients after 5 year interval after stereotactic radiosurgery for uveal melanoma stage T1, the tumor volume increased to 50 % of the primary tumor volume and repeated SRS was necessary. To find out the changes in melanoma characteristics after SRS in long term interval after irradiation is necessary to follow up the patient by an ophthalmologist regularly. One step LINAC based stereotactic radiosurgery with a single dose 35.0 Gy is one of treatment options to treat T1 to T3 stage posterior uveal melanoma and to preserve the eye globe. In some cases it is possible to repeat the SRS after more than 5 year interval (Fig. 8, Ref. 23).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, J-Y; Huang, B-T; Zhang, W-Z

Purpose: To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed-gantry intensity-modulated radiotherapy (IMRT) technique for early-stage nasopharyngeal carcinoma. Methods: CT datasets of ten patients with early-stage nasopharyngeal carcinoma were included. Dual-arc VMAT and nine-field IMRT plans were generated for each case, and were then compared in terms of planning-target-volume (PTV) coverage, conformity index (CI) and homogeneity index (HI), as well as organ-at-risk (OAR) sparing, planning time, monitor units (MUs) and delivery time. Results: Compared with the IMRT plans, the VMAT plans provided comparable HI and CI of PTVnx (PTV of primary tumor of nasopharynx), superior CI and inferior HImore » of PTVnd (PTV of lymph nodes), as well as superior CI and comparable HI of PTV60 (high-risk PTV). The VMAT plans provided better sparing of the spinal cord, oral cavity and normal tissue, but inferior sparing of the brainstem planning OAR volume (PRV), larynx and parotids, as well as comparable sparing of the spinal cord PRV, brainstem, lenses, optic nerves, optic chiasm. Moreover, the average planning time (181.6 ± 36.0 min) for the VMAT plans was 171% more than that of the IMRT plans (68.1 ± 7.6 min). The MUs of the VMAT plans (609 ± 43) were 70% lower than those of the IMRT plans (2071 ± 262), while the average delivery time (2.2 ± 0.1 min) was 66% less than that of the IMRT plans (6.6 ± 0.4 min). Conclusion: Compared with the IMRT technique, the VMAT technique can achieve similar or slightly superior target dose distribution, with no significant advantages on OAR sparing, and it can achieve significant reductions of MUs and delivery time.« less

Segmentation editing improves efficiency while reducing inter-expert variation and maintaining accuracy for normal brain tissues in the presence of space-occupying lesions

PubMed Central

Deeley, MA; Chen, A; Datteri, R; Noble, J; Cmelak, A; Donnelly, EF; Malcolm, A; Moretti, L; Jaboin, J; Niermann, K; Yang, Eddy S; Yu, David S; Dawant, BM

2013-01-01

Image segmentation has become a vital and often rate limiting step in modern radiotherapy treatment planning. In recent years the pace and scope of algorithm development, and even introduction into the clinic, have far exceeded evaluative studies. In this work we build upon our previous evaluation of a registration driven segmentation algorithm in the context of 8 expert raters and 20 patients who underwent radiotherapy for large space-occupying tumors in the brain. In this work we tested four hypotheses concerning the impact of manual segmentation editing in a randomized single-blinded study. We tested these hypotheses on the normal structures of the brainstem, optic chiasm, eyes and optic nerves using the Dice similarity coefficient, volume, and signed Euclidean distance error to evaluate the impact of editing on inter-rater variance and accuracy. Accuracy analyses relied on two simulated ground truth estimation methods: STAPLE and a novel implementation of probability maps. The experts were presented with automatic, their own, and their peers’ segmentations from our previous study to edit. We found, independent of source, editing reduced inter-rater variance while maintaining or improving accuracy and improving efficiency with at least 60% reduction in contouring time. In areas where raters performed poorly contouring from scratch, editing of the automatic segmentations reduced the prevalence of total anatomical miss from approximately 16% to 8% of the total slices contained within the ground truth estimations. These findings suggest that contour editing could be useful for consensus building such as in developing delineation standards, and that both automated methods and even perhaps less sophisticated atlases could improve efficiency, inter-rater variance, and accuracy. PMID:23685866

Dosimetric Comparison of Intensity-Modulated Stereotactic Radiotherapy With Other Stereotactic Techniques for Locally Recurrent Nasopharyngeal Carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kung, Shiris Wai Sum; Wu, Vincent Wing Cheung; Kam, Michael Koon Ming, E-mail: kamkm@yahoo.co

2011-01-01

Purpose: Locally recurrent nasopharyngeal carcinoma (NPC) patients can be salvaged by reirradiation with a substantial degree of radiation-related complications. Stereotactic radiotherapy (SRT) is widely used in this regard because of its rapid dose falloff and high geometric precision. The aim of this study was to examine whether the newly developed intensity-modulated stereotactic radiotherapy (IMSRT) has any dosimetric advantages over three other stereotactic techniques, including circular arc (CARC), static conformal beam (SmMLC), and dynamic conformal arc (mARC), in treating locally recurrent NPC. Methods and Materials: Computed tomography images of 32 patients with locally recurrent NPC, previously treated with SRT, were retrievedmore » from the stereotactic planning system for contouring and computing treatment plans. Treatment planning of each patient was performed for the four treatment techniques: CARC, SmMLC, mARC, and IMSRT. The conformity index (CI) and homogeneity index (HI) of the planning target volume (PTV) and doses to the organs at risk (OARs) and normal tissue were compared. Results: All four techniques delivered adequate doses to the PTV. IMSRT, SmMLC, and mARC delivered reasonably conformal and homogenous dose to the PTV (CI <1.47, HI <0.53), but not for CARC (p < 0.05). IMSRT presented with the smallest CI (1.37) and HI (0.40). Among the four techniques, IMSRT spared the greatest number of OARs, namely brainstem, temporal lobes, optic chiasm, and optic nerve, and had the smallest normal tissue volume in the low-dose region. Conclusion: Based on the dosimetric comparison, IMSRT was optimal for locally recurrent NPC by delivering a conformal and homogenous dose to the PTV while sparing OARs.« less

Multimodal Navigation in Endoscopic Transsphenoidal Resection of Pituitary Tumors Using Image-Based Vascular and Cranial Nerve Segmentation: A Prospective Validation Study.

PubMed

Dolati, Parviz; Eichberg, Daniel; Golby, Alexandra; Zamani, Amir; Laws, Edward

2016-11-01

Transsphenoidal surgery (TSS) is the most common approach for the treatment of pituitary tumors. However, misdirection, vascular damage, intraoperative cerebrospinal fluid leakage, and optic nerve injuries are all well-known complications, and the risk of adverse events is more likely in less-experienced hands. This prospective study was conducted to validate the accuracy of image-based segmentation coupled with neuronavigation in localizing neurovascular structures during TSS. Twenty-five patients with a pituitary tumor underwent preoperative 3-T magnetic resonance imaging (MRI), and MRI images loaded into the navigation platform were used for segmentation and preoperative planning. After patient registration and subsequent surgical exposure, each segmented neural or vascular element was validated by manual placement of the navigation probe or Doppler probe on or as close as possible to the target. Preoperative segmentation of the internal carotid artery and cavernous sinus matched with the intraoperative endoscopic and micro-Doppler findings in all cases. Excellent correspondence between image-based segmentation and the endoscopic view was also evident at the surface of the tumor and at the tumor-normal gland interfaces. Image guidance assisted the surgeons in localizing the optic nerve and chiasm in 64% of cases. The mean accuracy of the measurements was 1.20 ± 0.21 mm. Image-based preoperative vascular and neural element segmentation, especially with 3-dimensional reconstruction, is highly informative preoperatively and potentially could assist less-experienced neurosurgeons in preventing vascular and neural injury during TSS. In addition, the accuracy found in this study is comparable to previously reported neuronavigation measurements. This preliminary study is encouraging for future prospective intraoperative validation with larger numbers of patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Long-Term Outcomes of Fractionated Stereotactic Radiation Therapy for Pituitary Adenomas at the BC Cancer Agency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Julian O.; Ma, Roy; Division of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, Vancouver

2013-11-01

Purpose: To assess the long-term disease control and toxicity outcomes of fractionated stereotactic radiation therapy (FSRT) in patients with pituitary adenomas treated at the BC Cancer Agency. Methods and Materials: To ensure a minimum of 5 years of clinical follow-up, this study identified a cohort of 76 patients treated consecutively with FSRT between 1998 and 2007 for pituitary adenomas: 71% (54/76) had nonfunctioning and 29% (22/76) had functioning adenomas (15 adrenocorticotrophic hormone-secreting, 5 growth hormone-secreting, and 2 prolactin-secreting). Surgery was used before FSRT in 96% (73/76) of patients. A median isocenter dose of 50.4 Gy was delivered in 28 fractions,more » with 100% of the planning target volume covered by the 90% isodose. Patients were followed up clinically by endocrinologists, ophthalmologists, and radiation oncologists. Serial magnetic resonance imaging was used to assess tumor response. Results: With a median follow-up time of 6.8 years (range, 0.6 - 13.1 years), the 7-year progression-free survival was 97.1% and disease-specific survival was 100%. Of the 2 patients with tumor progression, both had disease control after salvage surgery. Of the 22 patients with functioning adenomas, 50% (11/22) had complete and 9% (2/22) had partial responses after FSRT. Of the patients with normal pituitary function at baseline, 48% (14/29) experienced 1 or more hormone deficiencies after FSRT. Although 79% (60/76) of optic chiasms were at least partially within the planning target volumes, no patient experienced radiation-induced optic neuropathy. No patient experienced radionecrosis. No secondary malignancy occurred during follow-up. Conclusion: In this study of long-term follow-up of patients treated for pituitary adenomas, FSRT was safe and effective.« less

Whole-brain hippocampal sparing radiation therapy: Volume-modulated arc therapy vs intensity-modulated radiation therapy case study.

PubMed

Lee, Katrina; Lenards, Nishele; Holson, Janice

2016-01-01

The hippocampus is responsible for memory and cognitive function. An ongoing phase II clinical trial suggests that sparing dose to the hippocampus during whole-brain radiation therapy can help preserve a patient׳s neurocognitive function. Progressive research and advancements in treatment techniques have made treatment planning more sophisticated but beneficial for patients undergoing treatment. The aim of this study is to evaluate and compare hippocampal sparing whole-brain (HS-WB) radiation therapy treatment planning techniques using volume-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT). We randomly selected 3 patients to compare different treatment techniques that could be used for reducing dose to the hippocampal region. We created 2 treatment plans, a VMAT and an IMRT, from each patient׳s data set and planned on the Eclipse 11.0 treatment planning system (TPS). A total of 6 plans (3 IMRT and 3 VMAT) were created and evaluated for this case study. The physician contoured the hippocampus as per the Radiation Therapy Oncology Group (RTOG) 0933 protocol atlas. The organs at risk (OR) were contoured and evaluated for the plan comparison, which included the spinal cord, optic chiasm, the right and left eyes, lenses, and optic nerves. Both treatment plans produced adequate coverage on the planning target volume (PTV) while significantly reducing dose to the hippocampal region. The VMAT treatment plans produced a more homogenous dose distribution throughout the PTV while decreasing the maximum point dose to the target. However, both treatment techniques demonstrated hippocampal sparing when irradiating the whole brain. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Ocular and neural distribution of feline herpesvirus-1 during active and latent experimental infection in cats

PubMed Central

2013-01-01

Background Herpes simplex virus 1 (HSV-1) and varicella zoster virus (VZV) cause extensive intra-ocular and neural infections in humans and are closely related to Felid herpes virus 1 (FeHV-1). We report the extent of intra-ocular replication and the extent and morphological aspects of neural replication during the acute and latent phases of FeHV-1 infection. Juvenile, SPF cats were inoculated with FeHV-1. Additional cats were used as negative controls. Cats were euthanized on days 6, 10, and 30 post-inoculation. Results FeHV-1 was isolated from the conjunctiva, cornea, uveal tract, retina, optic nerve, ciliary ganglion (CG), pterygopalatine ganglion (PTPG), trigeminal ganglion (TG), brainstem, visual cortex, cerebellum, and olfactory bulb of infected cats during the acute phase, but not the cranial cervical ganglion (CCG) and optic chiasm. Viral DNA was detected in all tissues during acute infection by a real-time quantitative PCR assay. On day 30, viral DNA was detected in all TG, all CCG, and 2 PTPG. Histologically mild inflammation and ganglion cell loss were noted within the TG during acute, but not latent infection. Using linear regression, a strong correlation existed between clinical score and day 30 viral DNA copy number within the TG. Conclusions The correlation between clinical score and day 30 viral DNA copy number suggests the severity of the acute clinical infection is related to the quantity of latent viral DNA. The histologic response was similar to that seen during HSV-1 or VZV infection. To the author’s knowledge this is the first report of FeHV-1 infection involving intraocular structures and autonomic ganglia. PMID:24053192

A note on the relative rates of degeneration in the crossed and the uncrossed retinofugal fibres in the opossum Didelphis marsupialis.

PubMed

Guillery, R W; Cavalcante, L A

1995-03-01

The rates at which the crossed and the uncrossed components of the retinofugal pathway degenerate in Didelphis has been studied by light and electron microscopical methods. We have found that in Didelphis, as in Monodelphis the two components can be clearly distinguished at the level of the chiasm. However, in contrast to the situation previously described for Monodelphis, where the uncrossed component degenerates more rapidly than the crossed, both components degenerate at the same rate.

Differential numbers of foci of lymphocytes within the brains of Lewis rats exposed to weak complex nocturnal magnetic fields during development of experimental allergic encephalomyelitis.

PubMed

Persinger, Michael A

2009-01-01

To discern if specific structures of the rat brain contained more foci of lymphocytes following induction of experimental allergic encephalomyelitis and exposures to weak, amplitude-modulated magnetic fields for 6 min once per hour during the scotophase, the residuals between the observed and predicted values for the numbers of foci for 320 structures were obtained. Compared to the brains of sham-field exposed rats, the brains of rats exposed to 7-Hz 50 nT (0.5 mG) amplitude-modulated fields showed more foci within hippocampal structures and the dorsal central grey of the midbrain while those exposed to 7-Hz 500 nT (5 mG) fields showed greater densities within the hypothalamus and optic chiasm. The brains of rats exposed to either the 50 nT or 500 nT amplitude-modulated 40-Hz fields displayed greater densities of foci within the midbrain structures related to rapid eye movement. Most of the enhancements of infiltrations within the magnetic field-exposed rats occurred in structures within periventricular or periaqueductal regions and were both frequency- and intensity-dependent. The specificity and complexity of the configurations of the residuals of the numbers of infiltrated foci following exposures to the different fields suggest that the brain itself may be a "sensory organ" for the detection of these stimuli.

Hourly oral sodium chloride for the rapid and predictable treatment of hyponatremia.

PubMed

Kerns, Eric; Patel, Shweta; Cohen, David M

2014-12-01

Hypertonic NaCl is first-line therapy for acute, severe and symptomatic hyponatremia; however, its use is often restricted to the intensive care unit (ICU). A 35-year-old female inpatient with an optic chiasm glioma and ventriculoperitoneal shunt for hydrocephalus developed acute hyponatremia (sodium 122 mEq/l) perhaps coinciding with haloperidol treatment. The sum of her urinary sodium and potassium concentrations was markedly hypertonic vis-à-vis plasma; it was inferred that serum sodium concentration would continue to fall even in the complete absence of fluid intake. Intravenous (i.v.) 3% NaCl was recommended; however, a city-wide public health emergency precluded her transfer to the ICU. She was treated with hourly oral NaCl tablets in a dose calculated to deliver the equivalent of 0.5 ml/kg/h of 3% NaCl with an objective of increasing the serum sodium concentration by 6 mEq/l. She experienced a graded and predictable increase in serum sodium concentration. A slight overshoot to 129 mEq/l was rapidly corrected with 0.25 l of D5W, and she stabilized at 127 mEq/l. We conclude that hourly oral NaCl, in conjunction with careful monitoring of the serum sodium concentration, may provide an attractive alternative to i.v. 3% NaCl for selected patients with severe hyponatremia.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, J; Kim, S; Hristov, D

Purpose: To assess the potential benefit of trajectory modulated arc therapy (TMAT) for treatments of small benign intracranial tumor, pituitary adenoma. Methods: A TMAT planning platform that incorporates complex source motion trajectory involving synchronized gantry rotation with translational and rotational couch movement was used for the study. The platform couples an interactive trajectory generation tool with a VMAT algorithm that performs multi-resolution, progressive sampling MLC optimization on a user-designed trajectory. A continuous couch rotation of 160° angular span with ±20° mini gantry arcs was used to emulate a non-coplanar horizontal arc-like trajectory. Compared to conventional non-coplanar gantry arcs (60°-100° gantrymore » rotation with couch kicks), TMAT limited the unnecessary low to medium dose spread in the anterior and posterior directions, where primary OARs (e.g., brainstem, optic chiasm, optic nerves, and lens) are in close proximity to the targeted pituitary tumor volume. For 5 standard fractionation pituitary adenoma cases (50.4Gy/28fractions), TMAT and non-coplanar VMAT plans were generated and compared under equivalent objectives/constraints. TMAT delivery was implemented and demonstrated on Varian TrueBeam via XML scripts. Results: Both techniques showed good target coverage while OARs were able to meet the constraints on QUANTEC guidelines. Notably, TMAT decreased the dose deposition in the anterior-to-posterior direction surrounding PTV. TMAT significantly reduced the mean doses on brainstem, optic nerves, eyes and lens by 47.29%±13.17%, 28.51%±8.68%, 80.82%±8.71% and 65.38%±19.99% compared with VMAT, all p≤0.01. Percentage reductions of maximum point dose in eyes and lens were 75.68%±10.30% and 70.72%±18.62% respectively for TMAT versus VMAT, all p≤0.01. A representative isocentric TMAT pituitary plan was delivered via an XML script with 200 control points and 282 MUs. Conclusion: Deliverable TMAT plans were achieved in developer mode in TrueBeam. TMAT was shown to be superior for pituitary adenoma irradiation in terms of OARs sparing.« less

Exchange transfusion with fluorocarbon for studying synaptically evoked optical signal in rat cortex.

PubMed

Nomura, Y; Fujii, F; Sato, C; Nemoto, M; Tamura, M

2000-02-01

Optical imaging of intrinsic signal is a powerful technique for studying the functional organization of the brain [T. Bonhoeffer, D. S. Kim, D. Malonek, D. Shoham, A. Grinvald, Optical imaging of the layout of functional domains in area 17 and across the area 17/18 border in cat visual cortex, Eur. J. Neurosci. 7 (1995) 1973-1988; M. Hubener, D. Shoham, A. Grinvald, T. Bonhoeffer, Spatial relationships among three columnar systems in cat area 17, J. Neurosci. 17 (1997) 9270-9284; D. Malonek, A. Grinvald, Interactions between electrical activity and cortical microcirculation revealed by imaging spectroscopy: implications for functional brain mapping, Science 272 (1996) 551-554; A. Shmuel, A. Grinvald, Functional organization for direction of motion and its relationship to orientation maps in cat area 18, J. Neurosci. 16 (1996) 6945-6964] [1] [10] [14] [22]. Three components of intrinsic optical signal can be distinguished. Two of these components can be attributed either to changes in blood volume or to changes in oxygen consumption [R.D. Frostig, E.E. Lieke, D.Y. Ts'o, A. Grinvald, Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in vivo high resolution optical imaging of intrinsic signals, Proc. Natl. Acad. Sci. U. S. A. 87 (1990) 6082-6086] [7]. The origin of the third component is not yet clear but the component seems to be based on scattered light [H.U. Dodt, G. D'Arcangelo, E. Pestel, W. Zieglgansberger, The spread of excitation in neocortical columns visualized with infrared-dark field videomicroscopy, NeuroReport 7 (1996) 1553-1558; K. Holthoff, O.W. Witte, Intrinsic optical signals in rat neocortical slices measured with near-infrared dark-field microscopy reveal changes in extracellular space, J. Neurosci. 16 (1996) 2740-2749; B.A. MacVicar, D. Hochman, Imaging of synaptically evoked intrinsic optical signals in hippocampal slices, J. Neurosci. 11 (1991) 1458-1469; L. Trachsel, H.U. Dodt, W. Zieglgansberger, The intrinsic optical signal evoked by chiasm stimulation in the rat suprachiasmatic nuclei exhibits GABAergic day-night variation, Eur. J. Neurosci. 8 (1996) 319-328] [3] [9] [13] [24]. A spectral fitting method with three components is used for the analysis of intrinsic optical signal [M. Nemoto, Y. Nomura, C. Sato, M. Tamura, K. Houkin, I. Koyanagi, H. Abe, Analysis of optical signals evoked by peripheral nerve stimulation in rat somatosensory cortex: dynamic changes in hemoglobin concentration and oxygenation, J. Cereb. Blood Flow Metab. 19 (1999) 246-259] [17]. In order to validate the analysis, we need the knowledge on contribution of signal resulted from hemoglobin to total intrinsic optical signal. The exchange transfusion with fluorocarbon has the advantage that can change the spectral contribution of hemoglobin [M. Ferrari, M.A. Williams, D.A. Wilson, N.V. Thakor, R.J. Traystman, D.F. Hanley, Cat brain cytochrome-c oxidase redox changes induced by hypoxia after blood-fluorocarbon exchange transfusion, Am. J. Physiol. 269 (1995) H417-H424; A.L. Sylvia, C.A. Piantadosi, O(2) dependence of in vivo brain cytochrome redox responses and energy metabolism in bloodless rats, J. Cereb. Blood Flow Metab. 8 (1988) 163-172] [6] [23]. Here we describe a new method of the reduction of hemoglobin signal from somatosensory evoked optical intrinsic signal in rat cortex by the combination of exchange transfusion with fluorocarbon and imaging system of thinned skull cranial window. The method allows for the study of the synaptically evoked changes in light scattering as well as fluorescence of calcium indicator or voltage-sensitive dye without absorption of hemoglobin.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pirlepesov, F.; Shin, J.; Moskvin, V. P.

Purpose: Dose weighted Linear Energy Transfer (LETd) analysis of critical structures may be useful in understanding the side effects of the proton therapy. The objective is to analyze the differences between LETd and dose distributions in brain tumor patients receiving double scattering proton therapy, to quantify LETd variation in critical organs, and to identify beam arrangements contributing to high LETd in critical organs. Methods: Monte Carlo simulations of 9 pediatric brain tumor patients were performed. The treatment plans were reconstructed with the TOPAS Monte Carlo code to calculate LETd and dose. The beam data were reconstructed proximal to the aperturemore » of the double scattering nozzle. The dose and LETd to target and critical organs including brain stem, optic chiasm, lens, optic nerve, pituitary gland, and hypothalamus were computed for each beam. Results: Greater variability in LETd compared to dose was observed in the brainstem for patients with a variety of tumor types including 5 patients with tumors located in the posterior fossa. Approximately 20%–44% brainstem volume received LETd of 5kev/µm or greater from beams within gantry angles 180°±30° for 5 patients treated with a 3 beam arrangement. Critical organs received higher LETd when located in the vicinity of the beam distal edge. Conclusion: This study presents a novel strategy in the evaluation of the proton treatment impact on critical organs. While the dose to critical organs is confined below the required limits, the LETd may have significant variation. Critical organs in the vicinity of beam distal edge receive higher LETd and depended on beam arrangement, e.g. in posterior fossa tumor treatment, brainstem receive higher LETd from posterior-anterior beams. This study shows importance of the LETd analysis of the radiation impact on the critical organs in proton therapy and may be used to explain clinical imaging observations after therapy.« less

SU-F-T-392: Superior Brainstem and Cochlea Sparing with VMAT for Glioblastoma Multiforme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Briere, TM; McAleer, MF; Levy, LB

Purpose: Volumetric arc therapy (VMAT) can provide similar target coverage and normal tissue sparing as IMRT but with shorter treatment times. At our institution VMAT was adopted for the treatment glioblastoma multiforme (GBM) after a small number of test plans demonstrated its non-inferiority. In this study, we compare actual clinical treatment plans for a larger cohort of patients treated with either VMAT or IMRT. Methods: 90 GBM patients were included in this study, 45 treated with IMRT and 45 with VMAT. All planning target volumes (PTVs) were prescribed a dose of 50 Gy, with a simultaneous integrated boost to 60more » Gy. Most IMRT plans used 5 non-coplanar beams, while most VMAT plans used 2 coplanar beams. Statistical analysis was performed using Fisher’s exact test or the Wilcoxon-Mann-Whitney rank sum test. Included in the analysis were patient and treatment characteristics as well as the doses to the target volumes and organs at risk. Results: Treatment times for the VMAT plans were reduced by 5 minutes compared with IMRT. The PTV coverage was similar, with at least 95% covered for all plans, while the median boost PTV dose differed by 0.1 Gy between the IMRT and VMAT cohorts. The doses to the brain, optic chiasm, optic nerves and eyes were not significantly different. The mean dose to the brainstem, however, was 9.4 Gy less with VMAT (p<0.001). The dose to the ipsilateral and contralateral cochleae were respectively 19.7 and 9.5 Gy less (p<0.001). Conclusion: Comparison of clinical treatment plans for separate IMRT and VMAT cohorts demonstrates that VMAT can save substantial treatment time while providing similar target coverage and superior sparing of the brainstem and cochleae. To our knowledge this is the first study to demonstrate this benefit of VMAT in the management of GBM.« less

White Matter Atrophy and Cognitive Dysfunctions in Neuromyelitis Optica

PubMed Central

Blanc, Frederic; Noblet, Vincent; Jung, Barbara; Rousseau, François; Renard, Felix; Bourre, Bertrand; Longato, Nadine; Cremel, Nadjette; Di Bitonto, Laure; Kleitz, Catherine; Collongues, Nicolas; Foucher, Jack; Kremer, Stephane; Armspach, Jean-Paul; de Seze, Jerome

2012-01-01

Neuromyelitis optica (NMO) is an inflammatory disease of central nervous system characterized by optic neuritis and longitudinally extensive acute transverse myelitis. NMO patients have cognitive dysfunctions but other clinical symptoms of brain origin are rare. In the present study, we aimed to investigate cognitive functions and brain volume in NMO. The study population consisted of 28 patients with NMO and 28 healthy control subjects matched for age, sex and educational level. We applied a French translation of the Brief Repeatable Battery (BRB-N) to the NMO patients. Using SIENAx for global brain volume (Grey Matter, GM; White Matter, WM; and whole brain) and VBM for focal brain volume (GM and WM), NMO patients and controls were compared. Voxel-level correlations between diminished brain concentration and cognitive performance for each tests were performed. Focal and global brain volume of NMO patients with and without cognitive impairment were also compared. Fifteen NMO patients (54%) had cognitive impairment with memory, executive function, attention and speed of information processing deficits. Global and focal brain atrophy of WM but not Grey Matter (GM) was found in the NMO patients group. The focal WM atrophy included the optic chiasm, pons, cerebellum, the corpus callosum and parts of the frontal, temporal and parietal lobes, including superior longitudinal fascicle. Visual memory, verbal memory, speed of information processing, short-term memory and executive functions were correlated to focal WM volumes. The comparison of patients with, to patients without cognitive impairment showed a clear decrease of global and focal WM, including brainstem, corticospinal tracts, corpus callosum but also superior and inferior longitudinal fascicles. Cognitive impairment in NMO patients is correlated to the decreased of global and focal WM volume of the brain. Further studies are needed to better understand the precise origin of cognitive impairment in NMO patients, particularly in the WM. PMID:22509264

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenberger, Benjamin A.; Pulsifer, Margaret B.; Ebb, David H.

Purpose/Objective(s): Primary low-grade gliomas are common brain tumors of childhood, many of which require radiation therapy (RT) as definitive treatment. Increased conformality of RT could decrease the incidence and severity of late effects. We report our experience with 32 pediatric patients treated with proton RT. Methods and Materials: Thirty-two pediatric patients with low-grade gliomas of the brain or spinal cord were treated with proton RT from 1995 to 2007. Sixteen patients received at least 1 regimen of chemotherapy before definitive RT. The median radiation dose was 52.2 Gy{sub RBE} (48.6-54 Gy{sub RBE}). Results: The median age at treatment was 11.0 yearsmore » (range, 2.7-21.5 years), with a median follow-up time of 7.6 years (range, 3.2-18.2 years). The 6-year and 8-year rates of progression-free survival were 89.7% and 82.8%, respectively, with an 8-year overall survival of 100%. For the subset of patients who received serial neurocognitive testing, there were no significant declines in Full-Scale Intelligence Quotient (P=.80), with a median neurocognitive testing interval of 4.5 years (range, 1.2-8.1 years) from baseline to follow-up, but subgroup analysis indicated some significant decline in neurocognitive outcomes for young children (<7 years) and those with significant dose to the left temporal lobe/hippocampus. The incidence of endocrinopathy correlated with a mean dose of ≥40 Gy{sub RBE} to the hypothalamus, pituitary, or optic chiasm. Stabilization or improvement of visual acuity was achieved in 83.3% of patients at risk for radiation-induced injury to the optic pathways. Conclusions: This report of late effects in children with low-grade gliomas after proton RT is encouraging. Proton RT appears to be associated with good clinical outcome, especially when the tumor location allows for increased sparing of the left temporal lobe, hippocampus, and hypothalamic-pituitary axis.« less

SU-E-T-436: Fluence-Based Trajectory Optimization for Non-Coplanar VMAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smyth, G; Bamber, JC; Bedford, JL

2015-06-15

Purpose: To investigate a fluence-based trajectory optimization technique for non-coplanar VMAT for brain cancer. Methods: Single-arc non-coplanar VMAT trajectories were determined using a heuristic technique for five patients. Organ at risk (OAR) volume intersected during raytracing was minimized for two cases: absolute volume and the sum of relative volumes weighted by OAR importance. These trajectories and coplanar VMAT formed starting points for the fluence-based optimization method. Iterative least squares optimization was performed on control points 24° apart in gantry rotation. Optimization minimized the root-mean-square (RMS) deviation of PTV dose from the prescription (relative importance 100), maximum dose to the brainstemmore » (10), optic chiasm (5), globes (5) and optic nerves (5), plus mean dose to the lenses (5), hippocampi (3), temporal lobes (2), cochleae (1) and brain excluding other regions of interest (1). Control point couch rotations were varied in steps of up to 10° and accepted if the cost function improved. Final treatment plans were optimized with the same objectives in an in-house planning system and evaluated using a composite metric - the sum of optimization metrics weighted by importance. Results: The composite metric decreased with fluence-based optimization in 14 of the 15 plans. In the remaining case its overall value, and the PTV and OAR components, were unchanged but the balance of OAR sparing differed. PTV RMS deviation was improved in 13 cases and unchanged in two. The OAR component was reduced in 13 plans. In one case the OAR component increased but the composite metric decreased - a 4 Gy increase in OAR metrics was balanced by a reduction in PTV RMS deviation from 2.8% to 2.6%. Conclusion: Fluence-based trajectory optimization improved plan quality as defined by the composite metric. While dose differences were case specific, fluence-based optimization improved both PTV and OAR dosimetry in 80% of cases.« less

SU-E-T-479: IMRT Plan Recalculation in Patient Based On Dynalog Data and the Effect of a Single Failing MLC Motor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morcos, M; Mitrou, E

2015-06-15

Purpose: Using Linac dynamic logs (Dynalogs) we evaluate the impact of a single failing MLC motor on the deliverability of an IMRT plan by assessing the recalculated dose volume histograms (DVHs) taking the delivered MLC positions and beam hold-offs into consideration. Methods: This is a retrospective study based on a deteriorating MLC motor (leaf 36B) which was observed to be failing via Dynalog analysis. To investigate further, Eclipse-importable MLC files were generated from Dynalogs to recalculate the actual delivered dose and to assess the clinical impact through DVHs. All deliveries were performed on a Varian 21EX linear accelerator equipped withmore » Millennium-120 MLC. The analysis of Dynalog files and subsequent conversion to Eclipse-importable MLC files were all performed by in-house programming in Python. Effects on plan DVH are presented in the following section on a particular brain-IMRT plan which was delivered with a failing MLC motor which was then replaced. Results: Global max dose increased by 13.5%, max dose to the brainstem PRV increased by 8.2%, max dose to the optic chiasm increased by 7.6%, max dose to optic nerve increased by 8.8% and the mean dose to the PTV increased by 7.9% when comparing the original plan to the fraction with the failing MLC motor. The reason the dose increased was due to the failure being on the B-bank which is the lagging side on a sliding window delivery, therefore any failures on this side will cause an over-irradiation as the B-bank leaves struggles to keep the window from growing. Conclusion: Our findings suggest that a single failing MLC motor may jeopardize the entire delivery. This may be due to the bad MLC motor drawing too much current causing all MLCs on the same bank to underperform. This hypothesis will be investigated in a future study.« less

Anterior Gray Matter Pituicytic Heterotopia with Monomorphic Anterior Pituitary Cells: A Variant of Nonsecretory Pituitary Adenoma Neuronal Choristoma? Report of a Rare Case and Review of the Literature.

PubMed

Yowtak, June; Sharma, Suash; Forseen, Scott E; Alleyne, Cargill H

2017-01-01

Mixed tumors of adenomatous and neuronal cells in the sellar region are an uncommon finding. The origins of these heterogeneous tumors are unknown, and management remains unsettled. We report a very rare case of anterior gray matter pituicytic heterotopia with monomorphic anterior pituitary cells that likely represents a variant of nonsecreting pituitary adenoma neuronal choristoma (PANCH) with no ganglion cells. We also review the current literature for the various clinical presentations of PANCH. A 49-year-old female complaining of headache, blurred vision, and hair loss was found to have a nonsecretory sellar mass with compression of the optic chiasm on magnetic resonance imaging (MRI). The mass was excised via a transsphenoidal procedure. Histological analysis of tissue sections revealed heterotopic gray matter with reactive gliosis without ganglion cells or Herring bodies. Only 1 smear exhibited characteristics of a pituitary adenoma. The overall findings were most consistent with a variant of PANCH. At a postoperative follow-up of 4.5 years, there was resolution of visual symptoms, and the residual sellar mass was stable on MRI. Neuronal choristoma is hypothesized to originate from embryonal pituitary or hypothalamus, or by differentiation from pituitary adenoma cells. Surgery is the cornerstone of management, and the clinical course appears to be similar to that of nonfunctioning pituitary adenoma in reported cases. Copyright © 2016 Elsevier Inc. All rights reserved.

Intercellular communications within the rat anterior pituitary. XVI: postnatal changes of distribution of S-100 protein positive cells, connexin 43 and LH-RH positive sites in the pars tuberalis of the rat pituitary gland. An immunohistochemical and electron microscopic study.

PubMed

Wada, Ikuo; Sakuma, Eisuke; Shirasawa, Nobuyuki; Wakabayashi, Kenjiro; Otsuka, Takanobu; Hattori, Kazuki; Yashiro, Takashi; Herbert, Damon C; Soji, Tsuyoshi

2014-02-01

The architecture of luteinizing hormone-releasing hormone (LH-RH) nerve ends and the S-100 protein containing folliculo-stellate cells forming gap junctions in the pars tuberalis is basically important in understanding the regulation of the hormone producing mechanism of anterior pituitary glands. In this study, intact male rats 5-60 days old were prepared for immunohistochemistry and electron microscopy. From immunostained sections, the S-100 containing cells in pars tuberalis were first detected on day 30 and increased in number to day 60; this was parallel to the immunohistochemical staining of gap junction protein, connexin 43. LH-RH positive sites were clearly observed on just behind the optic chiasm and on the root of pituitary stalk on day 30. On day 60, the width of layer increased, while follicles and gap junctions were frequently observed between agranular cells in 10 or more layers of pars tuberalis. In the present study, we investigated the sexual maturation of the anterior pituitary glands through the postnatal development of S-100 positive cells, connexin 43 and LH-RH nerves. It is suggested that the folliculo-stellate cell system including the LH-RH neurons in the pars tuberalis participates in the control of LH secretion along with the portal vein system. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Precocious puberty and von Recklinghausen's disease].

PubMed

Barg, Ewa; Wikiera, Beata; Basiak, Aleksander; Głab, Ewa

2006-01-01

Von Recklinghausen's disease belongs to a group of neurocutaneous syndromes and is characterised by skin, nerve and bone abnormalities. We present a case of von Recklinghausen's disease and precocious puberty in 7-year-old boy. At the age of three café au lait spots on the skin and an incranial tumour situated near the optic chiasm--qualified as inoperable--were discovered. At the age of 7 first signs of precocious puberty appeared (pubic hair P3 and enlargement of the testes (15 ml) and penis). Laboratory measurements included: LH 7.5 mIU/ml, FSH 1.1 mIU/ml, testosterone 183 ng/ml, assessment of bone age: 9 years. The response to LHRH stimulation was characteristic for true precocious puberty (LH 15.9 mIU/ml and FSH 1.5 mIU/ml after 30 minutes). The MRI of the brain showed a tumour of the suprasellar region with compression of pituitary stalk. True precocious puberty was diagnosed. Treatment with Diphereline was introduced. At present the boy is 9 years old and has been treated with Diphereline for 16 months. The volume of the testicles has decreased to 7 ml and loss of pubic hair was noted. The MRI does not show any progression in tumour growth. The authors would like to underline the need of close observation of children with von Reclinghausen disease with regard to possibility of uncovering true precocious puberty which is critical for rapid diagnosis and introduction of correct treatment.

CyberKnife Radiosurgery in the Multimodal Management of Patients with Cushing Disease.

PubMed

Moore, Justin M; Sala, Elisa; Amorin, Alvaro; Martinez, Hector; Bhowmik, Aprotim C; Chang, Steven D; Soltys, Scott G; Harsh, Griffith R; Katznelson, Laurence

2018-04-01

Surgery is the primary treatment for Cushing disease. When surgery is unsuccessful in normalizing hypercortisolism, adjuvant radiation, such as stereotactic radiosurgery, may be useful to improve biochemical control. This retrospective study included a cohort of consecutive patients treated with CyberKnife (CK) radiosurgery for active Cushing disease at Stanford Hospital and Clinics. As first-line treatment, all patients underwent transsphenoidal surgery with histologic demonstration of an adrenocorticotropic hormone-producing pituitary adenoma. CK was performed as adjuvant therapy for persistent or recurrent disease. The median time between surgery and CK was 14 ± 34 months. Before CK, median maximal diameter of tumors was 9 mm (range, 7-32 mm), with cavernous sinus invasion in all patients (100%) and abutment of the optic chiasm in 1 patient (14.2%). With an average follow-up of 55.4 months, normalization of hypercortisolism was achieved in 4 patients (57.1%): 2 patients (28.5%) achieved normalization of the hypothalamic-pituitary-adrenal axis without glucocorticoid replacement, and 2 patients developed hypoadrenalism (28.5%). The median time to biochemical remission was 12.5 months. Hypopituitarism occurred in only 1 patient (14.2%), and no patients had visual complications. Time between surgery and radiotherapy of <14 months was associated with a significantly improved biochemical remission rate (P = 0.02). In a cohort of patients with Cushing disease, we demonstrate that CK is an effective treatment with rare complications. Copyright © 2018 Elsevier Inc. All rights reserved.

Stereoscopic virtual reality models for planning tumor resection in the sellar region.

PubMed

Wang, Shou-sen; Zhang, Shang-ming; Jing, Jun-jie

2012-11-28

It is difficult for neurosurgeons to perceive the complex three-dimensional anatomical relationships in the sellar region. To investigate the value of using a virtual reality system for planning resection of sellar region tumors. The study included 60 patients with sellar tumors. All patients underwent computed tomography angiography, MRI-T1W1, and contrast enhanced MRI-T1W1 image sequence scanning. The CT and MRI scanning data were collected and then imported into a Dextroscope imaging workstation, a virtual reality system that allows structures to be viewed stereoscopically. During preoperative assessment, typical images for each patient were chosen and printed out for use by the surgeons as references during surgery. All sellar tumor models clearly displayed bone, the internal carotid artery, circle of Willis and its branches, the optic nerve and chiasm, ventricular system, tumor, brain, soft tissue and adjacent structures. Depending on the location of the tumors, we simulated the transmononasal sphenoid sinus approach, transpterional approach, and other approaches. Eleven surgeons who used virtual reality models completed a survey questionnaire. Nine of the participants said that the virtual reality images were superior to other images but that other images needed to be used in combination with the virtual reality images. The three-dimensional virtual reality models were helpful for individualized planning of surgery in the sellar region. Virtual reality appears to be promising as a valuable tool for sellar region surgery in the future.

The Infundibular Recess Passes through the Entire Pituitary Stalk.

PubMed

Tsutsumi, S; Hori, M; Ono, H; Tabuchi, T; Aoki, S; Yasumoto, Y

2016-12-01

The infundibular recess (IR), commonly illustrated as a V-shaped hollow in the sagittal view, is recognized as a small extension of the third ventricle into the pituitary stalk. The precise morphology of the human IR is unknown. The present study sought to delineate the morphology of the IR using magnetic resonance imaging. Subjects included 100 patients without acute cerebral infarcts, intracranial hemorrhage, intrasellar or suprasellar cysts, hydrocephalus, inflammatory disease, or brain tumors. Patients with symptoms of increased intracranial pressure, intracranial hypotension, or pituitary dysfunction were excluded. Thin-sliced, seamless T2-weighted sequences involving the optic chiasm, entire pituitary stalk, and pituitary gland were performed in axial and sagittal planes for each patient. The numbers of slices delineating the pituitary stalk and IR were recorded from the axial images and quantified as ratios. The pituitary stalk consistently appeared as a styloid- or cone-shaped structure with variable inclinations toward the third ventricle floor. The IR was delineated as a smoothly tapering, tubular extension of the third ventricle located in the central portion of the pituitary stalk. In 81 % of patients, the IR passed through the entire length of the pituitary stalk and reached the upper surface of the pituitary gland, which was identified in 40 % of the midsagittal images. The IR is a cerebrospinal fluid-filled canal passing through the center of the pituitary stalk and connects the third ventricle to the pituitary gland. It may function in conjunction with the pituitary gland.

Hybrid Microscopic-Endoscopic Surgery for Craniopharyngioma in Neurosurgical Suite: Technical Notes.

PubMed

Ichikawa, Tomotsugu; Otani, Yoshihiro; Ishida, Joji; Fujii, Kentaro; Kurozumi, Kazuhiko; Ono, Shigeki; Date, Isao

2016-01-01

The best chance of curing craniopharyngioma is achieved by microsurgical total resection; however, its location adjacent to critical structures hinders complete resection without neurologic deterioration. Unrecognized residual tumor within microscopic blind spots might result in tumor recurrences. To improve outcomes, new techniques are necessary to visualize tissue within these blind spots. We examined the success of hybrid microscopic-endoscopic neurosurgery for craniopharyngioma in a neurosurgical suite. Four children with craniopharyngiomas underwent microscopic resection. When the neurosurgeon was confident that most of the visible tumor was removed but was suspicious of residual tumor within the blind spot, he or she used an integrated endoscope-holder system to inspect and remove any residual tumor. Two ceiling monitors were mounted side by side in front of the surgeon to display both microscopic and endoscopic views and to view both monitors simultaneously. Surgery was performed in all patients via the frontobasal interhemispheric approach. Residual tumors were observed in the sella (2 patients), on the ventral surface of the chiasm and optic nerve (1 patient), and in the third ventricle (1 patient) and were resected to achieve total resection. Postoperatively, visual function was improved in 2 patients and none exhibited deterioration related to the surgery. Simultaneous microscopic and endoscopic observation with the use of dual monitors in a neurosurgical suite was ergonomically optimal for the surgeon to perform microsurgical procedures and to avoid traumatizing surrounding vessels or neural tissues. Hybrid microscopic-endoscopic neurosurgery may contribute to safe, less-invasive, and maximal resection to achieve better prognosis in children with craniopharyngioma. Copyright © 2016 Elsevier Inc. All rights reserved.

Rapid Deterioration of Latent HBV Hepatitis during Cushing Disease and Posttraumatic Stress Disorder after Earthquake.

PubMed

Tashiro, Ryosuke; Ogawa, Yoshikazu; Tominaga, Teiji

2017-07-01

Reactivation of the hepatitis B virus (HBV) is a risk in the 350 million HBV carriers worldwide. HBV reactivation may cause hepatocellular carcinoma, cirrhosis, and fulminant hepatitis, and HBV reactivation accompanied with malignant tumor and/or chemotherapy is a critical problem for patients with chronic HBV infection. Multiple risk factors causing an immunosuppressive state can also induce HBV reactivation.We present a case of HBV reactivation during an immunosuppressive state caused by Cushing disease and physical and psychological stress after a disaster. A 47-year-old Japanese woman was an inactive HBV carrier until the Great East Japan Earthquake occurred and follow-up was discontinued. One year after the earthquake she had intractable hypertension, and her visual acuity gradually worsened. Head magnetic resonance imaging showed a sellar tumor compressing the optic chiasm, and hepatic dysfunction with HBV reactivation was identified. Endocrinologic examination established the diagnosis as Cushing disease. After normalization of hepatic dysfunction with antiviral therapy, transsphenoidal tumor removal was performed that resulted in subtotal removal except the right cavernous portion. Steroid hormone supplementation was discontinued after 3 days of administration, and gamma knife therapy was performed for the residual tumor. Eighteen months after the operation, adrenocorticotropic hormone and cortisol values returned to normal. The patient has been free from tumor regrowth and HBV reactivation throughout the postoperative course.Accomplishment of normalization with intrinsic steroid value with minimization of steroid supplementation should be established. Precise operative procedures and careful treatment planning are essential to avoid HBV reactivation in patients with this threatening condition. Georg Thieme Verlag KG Stuttgart · New York.

Pig brain stereotaxic standard space: mapping of cerebral blood flow normative values and effect of MPTP-lesioning.

PubMed

Andersen, Flemming; Watanabe, Hideaki; Bjarkam, Carsten; Danielsen, Erik H; Cumming, Paul

2005-07-15

The analysis of physiological processes in brain by position emission tomography (PET) is facilitated when images are spatially normalized to a standard coordinate system. Thus, PET activation studies of human brain frequently employ the common stereotaxic coordinates of Talairach. We have developed an analogous stereotaxic coordinate system for the brain of the Gottingen miniature pig, based on automatic co-registration of magnetic resonance (MR) images obtained in 22 male pigs. The origin of the pig brain stereotaxic space (0, 0, 0) was arbitrarily placed in the centroid of the pineal gland as identified on the average MRI template. The orthogonal planes were imposed using the line between stereotaxic zero and the optic chiasm. A series of mean MR images in the coronal, sagittal and horizontal planes were generated. To test the utility of the common coordinate system for functional imaging studies of minipig brain, we calculated cerebral blood flow (CBF) maps from normal minipigs and from minipigs with a syndrome of parkisonism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-poisoning. These maps were transformed from the native space into the common stereotaxic space. After global normalization of these maps, an undirected search for differences between the groups was then performed using statistical parametric mapping. Using this method, we detected a statistically significant focal increase in CBF in the left cerebellum of the MPTP-lesioned group. We expect the present approach to be of general use in the statistical parametric mapping of CBF and other physiological parameters in living pig brain.

An image-based model of brain volume biomarker changes in Huntington's disease.

PubMed

Wijeratne, Peter A; Young, Alexandra L; Oxtoby, Neil P; Marinescu, Razvan V; Firth, Nicholas C; Johnson, Eileanoir B; Mohan, Amrita; Sampaio, Cristina; Scahill, Rachael I; Tabrizi, Sarah J; Alexander, Daniel C

2018-05-01

Determining the sequence in which Huntington's disease biomarkers become abnormal can provide important insights into the disease progression and a quantitative tool for patient stratification. Here, we construct and present a uniquely fine-grained model of temporal progression of Huntington's disease from premanifest through to manifest stages. We employ a probabilistic event-based model to determine the sequence of appearance of atrophy in brain volumes, learned from structural MRI in the Track-HD study, as well as to estimate the uncertainty in the ordering. We use longitudinal and phenotypic data to demonstrate the utility of the patient staging system that the resulting model provides. The model recovers the following order of detectable changes in brain region volumes: putamen, caudate, pallidum, insula white matter, nonventricular cerebrospinal fluid, amygdala, optic chiasm, third ventricle, posterior insula, and basal forebrain. This ordering is mostly preserved even under cross-validation of the uncertainty in the event sequence. Longitudinal analysis performed using 6 years of follow-up data from baseline confirms efficacy of the model, as subjects consistently move to later stages with time, and significant correlations are observed between the estimated stages and nonimaging phenotypic markers. We used a data-driven method to provide new insight into Huntington's disease progression as well as new power to stage and predict conversion. Our results highlight the potential of disease progression models, such as the event-based model, to provide new insight into Huntington's disease progression and to support fine-grained patient stratification for future precision medicine in Huntington's disease.

Clinical outcomes in male patients with lactotroph adenomas who required pituitary surgery: a retrospective single center study.

PubMed

Liu, Winnie; Zahr, Roula Shraiky; McCartney, Shirley; Cetas, Justin S; Dogan, Aclan; Fleseriu, Maria

2018-06-23

Lactotroph adenomas (LA) are the most frequently encountered pituitary tumors. Although more frequently observed in women, LAs in men were recently included in a more aggressive category regardless of histological grading, by the WHO. We aimed to perform a rigorous retrospective review of a single center's pre-operative evaluation, patient characteristics and outcomes of male LAs patients requiring pituitary surgery. A retrospective review, over 11 years, of patients who underwent resection of a pituitary adenoma at a single center was conducted. Predictors of persistent disease in male LAs patients along with a comparison to predictors of silent corticotroph adenomas (SCAs) patients who also underwent surgery at the center was also conducted. Thirty-one male patients with LAs were identified. When compared to SCAs patients, LAs male patients were younger (41 vs. 50 years of age, p = 0.01). Men with LAs had more invasive tumors (75% vs. 44.7% p = 0.02). More LAs in men had residual tumor after surgery than patients with SCA (92.6% vs. 42.1%, p < 0.001). Male patients with LAs and patients with SCA had similar rates of requiring additional surgery (28.9% vs. 24.1%, p = NS) and radiation therapy (18.4% vs. 19.4%, p = NS). High rates of DA resistance, invasive tumors and postoperative residual disease in male patients with LA who required surgery are shown. Surgery improved optic chiasm compression, PRL level and central hypogonadism but, not surprisingly, failed to normalize other pituitary hormones and/or eliminate need for DA therapy.

Fraction-variant beam orientation optimization for non-coplanar IMRT

NASA Astrophysics Data System (ADS)

O'Connor, Daniel; Yu, Victoria; Nguyen, Dan; Ruan, Dan; Sheng, Ke

2018-02-01

Conventional beam orientation optimization (BOO) algorithms for IMRT assume that the same set of beam angles is used for all treatment fractions. In this paper we present a BOO formulation based on group sparsity that simultaneously optimizes non-coplanar beam angles for all fractions, yielding a fraction-variant (FV) treatment plan. Beam angles are selected by solving a multi-fraction fluence map optimization problem involving 500-700 candidate beams per fraction, with an additional group sparsity term that encourages most candidate beams to be inactive. The optimization problem is solved using the fast iterative shrinkage-thresholding algorithm. Our FV BOO algorithm is used to create five-fraction treatment plans for digital phantom, prostate, and lung cases as well as a 30-fraction plan for a head and neck case. A homogeneous PTV dose coverage is maintained in all fractions. The treatment plans are compared with fraction-invariant plans that use a fixed set of beam angles for all fractions. The FV plans reduced OAR mean dose and D 2 values on average by 3.3% and 3.8% of the prescription dose, respectively. Notably, mean OAR dose was reduced by 14.3% of prescription dose (rectum), 11.6% (penile bulb), 10.7% (seminal vesicle), 5.5% (right femur), 3.5% (bladder), 4.0% (normal left lung), 15.5% (cochleas), and 5.2% (chiasm). D 2 was reduced by 14.9% of prescription dose (right femur), 8.2% (penile bulb), 12.7% (proximal bronchus), 4.1% (normal left lung), 15.2% (cochleas), 10.1% (orbits), 9.1% (chiasm), 8.7% (brainstem), and 7.1% (parotids). Meanwhile, PTV homogeneity defined as D 95/D 5 improved from .92 to .95 (digital phantom), from .95 to .98 (prostate case), and from .94 to .97 (lung case), and remained constant for the head and neck case. Moreover, the FV plans are dosimetrically similar to conventional plans that use twice as many beams per fraction. Thus, FV BOO offers the potential to reduce delivery time for non-coplanar IMRT.

ON THE BENEFITS AND RISKS OF PROTON THERAPY IN PEDIATRIC CRANIOPHARYNGIOMA

PubMed Central

Beltran, Chris; Roca, Monica; Merchant, Thomas E.

2013-01-01

Purpose Craniopharyngioma is a pediatric brain tumor whose volume is prone to change during radiation therapy. We compared photon- and proton-based irradiation methods to determine the effect of tumor volume change on target coverage and normal tissue irradiation in these patients. Methods and Materials For this retrospective study, we acquired imaging and treatment-planning data from 14 children with craniopharyngioma (mean age, 5.1 years) irradiated with photons (54 Gy) and monitored by weekly magnetic resonance imaging (MRI) examinations during radiation therapy. Photon intensity-modulated radiation therapy (IMRT), double-scatter proton (DSP) therapy, and intensity-modulated proton therapy (IMPT) plans were created for each patient based on his or her pre-irradiation MRI. Target volumes were contoured on each weekly MRI scan for adaptive modeling. The measured differences in conformity index (CI) and normal tissue doses, including functional sub-volumes of the brain, were compared across the planning methods, as was target coverage based on changes in target volumes during treatment. Results CI and normal tissue dose values of IMPT plans were significantly better than those of the IMRT and DSP plans (p < 0.01). Although IMRT plans had a higher CI and lower optic nerve doses (p < 0.01) than did DSP plans, DSP plans had lower cochlear, optic chiasm, brain, and scanned body doses (p < 0.01). The mean planning target volume (PTV) at baseline was 54.8 cm3, and the mean increase in PTV was 11.3% over the course of treatment. The dose to 95% of the PTV was correlated with a change in the PTV; the R2 values for all models, 0.73 (IMRT), 0.38 (DSP), and 0.62 (IMPT), were significant (p < 0.01). Conclusions Compared with photon IMRT, proton therapy has the potential to significantly reduce whole-brain and -body irradiation in pediatric patients with craniopharyngioma. IMPT is the most conformal method and spares the most normal tissue; however, it is highly sensitive to target volume changes, whereas the DSP method is not. PMID:21570209

SU-E-T-581: Planning Evaluation of Step-And-Shoot IMRT, RapidArc and Helical TomoTherapy for Hippocampal-Avoidance Whole Brain Radiotherapy (HA-WBRT).

PubMed

Evans, J; Chen, Q; Wuthrick, E; Weldon, M; Rong, Y

2012-06-01

Several planning strategies are available for hippocampal- avoidance whole-brain radiotherapy (HA-WBRT) following RTOG protocol 0933, but have yet to be compared on a common set of patient data. In this inter-institutional investigation, we evaluate three modalities likely to be employed by protocol participants; step-and-shoot IMRT, volumetric modulated arc therapy, and helical tomotherapy. A common set of patients is used for comparison, including credentialing and successfully accrued patients. Eight patient datasets were selected and de-identified prior to planning. Structures were contoured by physicians per protocol using fused MRI datasets. Three plans were generated for each dataset: Philips Pinnacle 9-field non-coplanar IMRT using protocol recommended beam parameters, Varian's RapidArc using two coplanar arcs, and Accuray's TomoTherapy using a 1cm jaw width. With the goal of meeting the compliance criteria outlined in RTOG 0933 (target coverage and dose limits to the hippocampus and optic structures), three planners independently planned each modality without prior knowledge of the patient's other plans to reduce bias. The three plans for each patient were compared according to the protocol's dosimetric compliance criteria. A homogeneity index was also computed to compare target dose uniformity. All plans achieved the protocol dose criteria, except for one RapidArc plan with slightly inferior dose to the optic chiasm. TomoTherapy offered superior dose homogeneity for all patients. For the two linac based methods, RapidArc was found to provide dose homogeneity at least as good as, and in most cases superior to, 9-field step-and-shoot IMRT. Helical TomoTherapy offers superior dose homogeneity for HA-WBRT following RTOG 0933. Compared to step-and-shoot IMRT, volumetric modulated arc techniques, such as RapidArc, can offer improved homogeneity for HA- WBRT and are generally more efficient/expeditious to deliver than the noncoplanar 9-field arrangement recommended by the protocol, which uses 7 separate couch angles. © 2012 American Association of Physicists in Medicine.

GFAP-immunopositive structures in spiny dogfish, Squalus acanthias, and little skate, Raia erinacea, brains: differences have evolutionary implications.

PubMed

Kálmán, M; Gould, R M

2001-07-01

GFAP expression patterns were compared between the brains of a spiny dogfish (Squalus acanthias) and a little skate (Raia erinacea). After anesthesia, the animals were perfused with paraformaldehyde. Serial vibratome sections were immunostained against GFAP using the avidin-biotin method. Spiny dogfish brain contained mainly uniformly-distributed, radially arranged ependymoglia. From GFAP distribution, the layered organization in both the telencephalon and the tectum were visible. In the cerebellum, the molecular and granular layers displayed conspicuously different glial structures; in the former a Bergmann glia-like population was found. No true astrocytes (i.e., stellate-shaped cells) were found. Radial glial endfeet lined all meningeal surfaces. Radial fibers also seemed to form endfeet and en passant contacts on the vessels. Plexuses of fine perivascular glial fibers also contributed to the perivascular glia. Compared with spiny dogfish brain, GFAP expression in the little skate brain was confined. Radial glia were limited to a few areas, e.g., segments of the ventricular surface of the telencephalon, and the midline of the diencephalon and mesencephalon. Scarce astrocytes occurred in every brain part, but only the optic chiasm, and the junction of the tegmentum and optic tectum contained large numbers of astrocytes. Astrocytes formed the meningeal glia limitans and the perivascular glia. No GFAP-immunopositive Bergmann glia-like structure was found. Astrocytes seen in the little skate were clearly different from the mammalian and avian ones; they had a different process system - extra large forms were frequently seen, and the meningeal and perivascular cells were spread along the surface instead of forming endfeet by processes. The differences between Squalus and Raia astroglia were much like those found between reptiles versus mammals and birds. It suggests independent and parallel glial evolutionary processes in amniotes and chondrichthyans, seemingly correlated with the thickening of the brain wall, and the growing complexity of the brain. There is no strict correlation, however, between the replacement of radial ependymoglia with astrocytes, and the local thickness of the brain wall.

Predicting Patient-specific Dosimetric Benefits of Proton Therapy for Skull-base Tumors Using a Geometric Knowledge-based Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, David C.; Trofimov, Alexei V.; Winey, Brian A.

Purpose: To predict the organ at risk (OAR) dose levels achievable with proton beam therapy (PBT), solely based on the geometric arrangement of the target volume in relation to the OARs. A comparison with an alternative therapy yields a prediction of the patient-specific benefits offered by PBT. This could enable physicians at hospitals without proton capabilities to make a better-informed referral decision or aid patient selection in model-based clinical trials. Methods and Materials: Skull-base tumors were chosen to test the method, owing to their geometric complexity and multitude of nearby OARs. By exploiting the correlations between the dose and distance-to-targetmore » in existing PBT plans, the models were independently trained for 6 types of OARs: brainstem, cochlea, optic chiasm, optic nerve, parotid gland, and spinal cord. Once trained, the models could estimate the feasible dose–volume histogram and generalized equivalent uniform dose (gEUD) for OAR structures of new patients. The models were trained using 20 patients and validated using an additional 21 patients. Validation was achieved by comparing the predicted gEUD to that of the actual PBT plan. Results: The predicted and planned gEUD were in good agreement. Considering all OARs, the prediction error was +1.4 ± 5.1 Gy (mean ± standard deviation), and Pearson's correlation coefficient was 93%. By comparing with an intensity modulated photon treatment plan, the model could classify whether an OAR structure would experience a gain, with a sensitivity of 93% (95% confidence interval: 87%-97%) and specificity of 63% (95% confidence interval: 38%-84%). Conclusions: We trained and validated models that could quickly and accurately predict the patient-specific benefits of PBT for skull-base tumors. Similar models could be developed for other tumor sites. Such models will be useful when an estimation of the feasible benefits of PBT is desired but the experience and/or resources required for treatment planning are unavailable.« less

IMRT vs. 3D Noncoplanar Treatment Plans for Maxillary Sinus Tumors: A New Tool for Quantitative Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levin, Daphne; Menhel, Janna; Alezra, Dror

2008-01-01

We compared 9-field, equispaced intensity modulated radiation therapy (IMRT), 4- to 5-field, directionally optimized IMRT, and 3-dimensional (3D) noncoplanar planning approaches for tumors of the maxillary sinus. Ten patients were planned retrospectively to compare the different treatment techniques. Prescription doses were 60 to 70 Gy. Critical structures contoured included optic nerves and chiasm, lacrimal glands, lenses, and retinas. As an aid for plan assessment, we introduced a new tool: Critical Organ Scoring Index (COSI), which allows quantitative evaluation of the tradeoffs between target coverage and critical organ sparing. This index was compared with other, commonly used conformity indices. For amore » reliable assessment of both tumor coverage and dose to critical organs in the different planning techniques, we introduced a 2D, graphical representation of COSI vs. conformity index (CI). Dose-volume histograms and mean, maximum, and minimum organ doses were also compared. IMRT plans delivered lower doses to ipsilateral structures, but were unable to spare them. 3D plans delivered less dose to contralateral structures, and were more homogeneous, as well. Both IMRT approaches gave similar results. In cases where choice of optimal plan was difficult, the novel 2D COSI-CI representation gave an accurate picture of the tradeoffs between target coverage and organ sparing, even in cases where other conformity indices failed. Due to their unique anatomy, maxillary sinus tumors may benefit more from a noncoplanar approach than from IMRT. The new graphical representation proposed is a quick, visual, reliable tool, which may facilitate the physician's choice of best treatment plan for a given patient.« less

Elevated serum IGF-1 level enhances retinal and choroidal thickness in untreated acromegaly patients.

PubMed

Zhang, Xia; Ma, Jin; Wang, Yuhan; Li, Lüe; Gao, Lu; Guo, Xiaopeng; Xing, Bing; Zhong, Yong

2018-03-01

1) To compare the retinal, choroidal, Haller's layer, and Sattler's/choriocapillaris thicknesses of untreated acromegaly patients without chiasm compression or diabetes mellitus and healthy controls. 2) To evaluate the correlations of retinal and choroidal thicknesses with serum growth hormone (GH) and insulin-like growth factor 1 (IGF) burden. This prospective, case-control study included 27 untreated acromegaly patients and 27 sex-matched and age-matched controls. Subfoveal choroidal, Haller's layer and Sattler's/choriocapillaris thicknesses were determined by enhanced-depth imaging optical coherence tomography (EDI-OCT). Foveal and macular retinal thicknesses were determined with SD-OCT. GH and IGF-1 burdens were defined as the product of disease duration and treatment-naïve serum GH and IGF-1 levels. Compared with healthy controls, patients with acromegaly exhibited significantly increased foveal retinal (p = 0.003), subfoveal choroidal (p < 0.001), and Haller's layer (p < 0.001) thicknesses, with no differences in Sattler's/choriocapillaris layer thickness. Multiple point measurements in the posterior pole area showed equally increased nasal and temporal parts of the choroid. The retinal thickness maps of the two groups did not significantly differ. Correlation analysis indicated that choroidal thickness was significantly correlated with disease duration (p = 0.01), serum IGF-1 level (p = 0.03) and IGF-1 burden (p = 0.009). No significant correlations were detected between choroidal thickness and GH burden (p = 0.44). Retinal thickness was not significantly correlated with any factor. The choroidal thickness of acromegaly patients was greater than that of healthy controls and was significantly correlated with disease duration, IGF-1 level and IGF-1 burden, indicating that excessive serum IGF-1 and its exposure time have a combined effect on choroidal thickness.

Whole-Brain DTI Assessment of White Matter Damage in Children with Bilateral Cerebral Palsy: Evidence of Involvement beyond the Primary Target of the Anoxic Insult.

PubMed

Arrigoni, F; Peruzzo, D; Gagliardi, C; Maghini, C; Colombo, P; Iammarrone, F Servodio; Pierpaoli, C; Triulzi, F; Turconi, A C

2016-07-01

Cerebral palsy is frequently associated with both motor and nonmotor symptoms. DTI can characterize the damage at the level of motor tracts but provides less consistent results in nonmotor areas. We used a standardized pipeline of analysis to describe and quantify the pattern of DTI white matter abnormalities of the whole brain in a group of children with chronic bilateral cerebral palsy and periventricular leukomalacia. We also explored potential correlations between DTI and clinical scale metrics. Twenty-five patients (mean age, 11.8 years) and 25 healthy children (mean age, 11.8 years) were studied at 3T with a 2-mm isotropic DTI sequence. Differences between patients and controls were assessed both voxelwise and in ROIs obtained from an existing DTI atlas. Clinical metrics included the Gross Motor Function Classification System, the Manual Ability Classification System, and intelligence quotient. The voxel-level and ROI-level analyses demonstrated highly significant (P < .001) modifications of DTI measurements in patients at several levels: cerebellar peduncles, corticospinal tracts and posterior thalamic radiations, posterior corpus callosum, external capsule, anterior thalamic radiation, superior longitudinal fasciculi and corona radiata, optic nerves, and chiasm. The reduction of fractional anisotropy values in significant tracts was between 8% and 30%. Statistically significant correlations were found between motor impairment and fractional anisotropy in corticospinal tracts and commissural and associative tracts of the supratentorial brain. We demonstrated the involvement of several motor and nonmotor areas in the chronic damage associated with periventricular leukomalacia and showed new correlations between motor skills and DTI metrics. © 2016 by American Journal of Neuroradiology.

Water-filled balloon in the postoperative resection cavity improves dose distribution to target volumes in radiotherapy of maxillary sinus carcinoma.

PubMed

Zhang, Qun; Lin, Shi-Rong; He, Fang; Kang, De-Hua; Chen, Guo-Zhang; Luo, Wei

2011-11-01

Postoperative radiotherapy is a major treatment for patients with maxillary sinus carcinoma. However, the irregular resection cavity poses a technical difficulty for this treatment, causing uneven dose distribution to target volumes. In this study, we evaluated the dose distribution to target volumes and normal tissues in postoperative intensity-modulated radiotherapy (IMRT) after placing a water-filled balloon into the resection cavity. Three postoperative patients with advanced maxillary sinus carcinoma were selected in this trial. Water-filled balloons and supporting dental stents were fabricated according to the size of the maxillary resection cavity. Simulation CT scans were performed with or without water-filled balloons, IMRT treatment plans were established, and dose distribution to target volumes and organs at risk were evaluated. Compared to those in the treatment plan without balloons, the dose (D98) delivered to 98% of the gross tumor volume (GTV) increased by 2.1 Gy (P = 0.009), homogeneity index (HI) improved by 2.3% (P = 0.001), and target volume conformity index (TCI) of 68 Gy increased by 18.5% (P = 0.011) in the plan with balloons. Dosimetry endpoints of normal tissues around target regions in both plans were not significantly different (P > 0.05) except for the optic chiasm. In the plan without balloons, 68 Gy high-dose regions did not entirely cover target volumes in the ethmoid sinus, posteromedial wall of the maxillary sinus, or surgical margin of the hard palate. In contrast, 68 Gy high-dose regions entirely covered the GTV in the plan with balloons. These results suggest that placing a water-filled balloon in the resection cavity for postoperative IMRT of maxillary sinus carcinoma can reduce low-dose regions and markedly and simultaneously increase dose homogeneity and conformity of target volumes.

Endoscopic Endonasal Transplanum Transtuberculum Approach for the Resection of a Large Suprasellar Craniopharyngioma.

PubMed

Mangussi-Gomes, João; Vellutini, Eduardo A; Truong, Huy Q; Pahl, Felix H; Stamm, Aldo C

2018-04-01

Objectives  To demonstrate an endoscopic endonasal transplanum transtuberculum approach for the resection of a large suprasellar craniopharyngioma. Design  Single-case-based operative video. Setting  Tertiary center with dedicated skull base team. Participants  A 72-year-old male patient diagnosed with a suprasellar craniopharyngioma. Main Outcomes Measured  Surgical resection of the tumor and preservation of the normal surrounding neurovascular structures. Results  A 72-year-old male patient presented with a 1-year history of progressive bitemporal visual loss. He also referred symptoms suggestive of hypogonadism. Neurological examination was unremarkable and endocrine workup demonstrated mildly elevated prolactin levels. Magnetic resonance images demonstrated a large solid-cystic suprasellar lesion, consistent with the diagnosis of craniopharyngioma. The lesion was retrochiasmatic, compressed the optic chiasm, and extended into the interpeduncular cistern ( Fig. 1 ). Because of that, the patient underwent an endoscopic endonasal transplanum transtuberculum approach. 1 2 3 The nasal stage consisted of a transnasal transseptal approach, with complete preservation of the patient's left nasal cavity. 4 The cystic component of the tumor was decompressed and its solid part was resected. It was possible to preserve the surrounding normal neurovascular structures ( Fig. 2 ). Skull base reconstruction was performed with a dural substitute, a fascia lata graft, and a right nasoseptal flap ( Video 1 ). The patient did well after surgery and referred complete visual improvement. However, he also presented pan-hypopituitarism on long-term follow-up. Conclusions  The endoscopic endonasal route is a good alternative for the resection of suprasellar lesions. It permits tumor resection and preservation of the surrounding neurovascular structures while avoiding external incisions and brain retraction. The link to the video can be found at: https://youtu.be/zmgxQe8w-JQ .

Localization of connexin 43 gap junctions and hemichannels in tanycytes of adult mice.

PubMed

Szilvásy-Szabó, Anett; Varga, Edina; Beliczai, Zsuzsa; Lechan, Ronald M; Fekete, Csaba

2017-10-15

Tanycytes are specialized glial cells lining the lateral walls and the floor of the third ventricle behind the optic chiasm. In addition to functioning as barrier cells, they also have an important role in the regulation of neuroendocrine axes and energy homeostasis. To determine whether tanycytes communicate with each other via Connexin 43 (Cx43) gap junctions, individual tanycytes were loaded with Lucifer yellow (LY) through a patch pipette. In all cases, LY filled a larger group of tanycytes as well as blood vessels adjacent to tanycyte processes. The Cx43-blocker, carbenoxolone, inhibited spreading of LY. The greatest density of Cx43-immunoreactive spots was observed in the cell membrane of α-tanycyte cell bodies. Cx43-immunoreactivity was also present in the membrane of β-tanycyte cell bodies, but in lower density. Processes of both types of tanycytes also contained Cx43-immunoreactivity. At the ultrastructural level, Cx43-immunoreactivity was present in the cell membrane of all types of tanycytes including their ventricular surface, but gap junctions were more frequent among α-tanycytes. Cx43-immunoreactivity was also observed in the cell membrane between contacting tanycyte endfeet processes, and between tanycyte endfeet process and axon varicosities in the external zone of the median eminence and capillaries in the arcuate nucleus and median eminence. These results suggest that gap junctions are present not only among tanycytes, but also between tanycytes and the axons of hypophysiotropic neurons. Cx43 hemichannels may also facilitate the transport between tanycytes and extracellular fluids, including the cerebrospinal fluid, extracellular space of the median eminence and bloodstream. Copyright © 2017 Elsevier B.V. All rights reserved.

[Pituitary gland tumors].

PubMed

Jesser, J; Schlamp, K; Bendszus, M

2014-10-01

This article gives an overview of the most common tumors of the pituitary gland and the differential diagnostics with special emphasis on radiological diagnostic criteria. A selective search of the literature in PubMed was carried out. Pituitary adenomas constitute 10-15% of all intracranial tumors and are the most common tumors of the sellar region. Tumors smaller than 1 cm in diameter are called microadenomas while those larger than 1 cm in diameter are called macroadenomas. Approximately 65% of pituitary gland adenomas secrete hormones whereby approximately 50% secrete prolactin, 10% secrete growth hormone (somatotropin) and 6% secrete corticotropin. Other tumors located in the sella turcica can also cause endocrinological symptoms, such as an oversecretion of pituitary hormone or pituitary insufficiency by impinging on the pituitary gland or its stalk. When tumors spread into the space cranial to the sella turcica, they can impinge on the optic chiasm and cause visual disorders. A common differential diagnosis of a sellar tumor is a craniopharyngeoma. In children up to 10% of all intracranial tumors are craniopharyngeomas. Other differential diagnoses for sellar tumors are metastases, meningiomas, epidermoids and in rare cases astrocytomas, germinomas or Rathke cleft cysts As these tumors are located in an anatomically complex region of the skull base and are often very small, a highly focused imaging protocol is required. The currently favored modality is magnetic resonance imaging (MRI) with the administration of a contrast agent. The sellar region should be mapped in thin slices. In cases of suspected microadenoma the imaging protocol should also contain a sequence with dynamic contrast administration in order to assess the specific enhancement characteristics of the tumor and the pituitary gland.

Management of nonfunctioning pituitary incidentaloma.

PubMed

Galland, Françoise; Vantyghem, Marie-Christine; Cazabat, Laure; Boulin, Anne; Cotton, François; Bonneville, Jean-François; Jouanneau, Emmanuel; Vidal-Trécan, Gwénaelle; Chanson, Philippe

2015-07-01

Prevalence of pituitary incidentaloma is variable: between 1.4% and 27% at autopsy, and between 3.7% and 37% on imaging. Pituitary microincidentalomas (serendipitously discovered adenoma <1cm in diameter) may increase in size, but only 5% exceed 10mm. Pituitary macroincidentalomas (serendipitously discovered adenoma>1cm in diameter) show increased size in 20-24% and 34-40% of cases at respectively 4 and 8years' follow-up. Radiologic differential diagnosis requires MRI centered on the pituitary gland. Initial assessment of nonfunctioning (NF) microincidentaloma is firstly clinical, the endocrinologist looking for signs of hypersecretion (signs of hyperprolactinemia, acromegaly or Cushing's syndrome), followed up by systematic prolactin and IGF-1 assay. Initial assessment of NF macroincidentaloma is clinical, the endocrinologist looking for signs of hormonal hypersecretion or hypopituitarism, followed up by hormonal assay to screen for hypersecretion or hormonal deficiency and by ophthalmologic assessment (visual acuity and visual field) if and only if the lesion is near the optic chiasm (OC). NF microincidentaloma of less than 5mm requires no surveillance; those of≥5mm are not operated on but rather monitored on MRI at 6months and then 2years. Macroincidentaloma remote from the OC is monitored on MRI at 1year, with hormonal exploration (for anterior pituitary deficiency), then every 2years. When macroincidentaloma located near the OC is managed by surveillance rather than surgery, MRI is recommended at 6months, with hormonal and visual exploration, then annual MRI and hormonal and visual assessment every 6months. Surgery is indicated in the following cases: evolutive NF microincidentaloma, NF macroincidentaloma associated with hypopituitarism or showing progression, incidentaloma compressing the OC, possible malignancy, non-compliant patient, pregnancy desired in the short-term, or context at risk of apoplexy. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Volumetric Modulated Arc-Based Hypofractionated Stereotactic Radiotherapy for the Treatment of Selected Intracranial Arteriovenous Malformations: Dosimetric Report and Early Clinical Experience

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subramanian, Sai; Srinivas, Chilukuri; Ramalingam, K.

2012-03-01

Purpose: To evaluate, with a dosimetric and clinical feasibility study, RapidArc (a volumetric modulated arc technique) for hypofractionated stereotactic radiotherapy treatment of large arteriovenous malformations (AVMs). Methods and Materials: Nine patients were subject to multimodality imaging (magnetic resonance, computed tomography, and digital subtraction angiography) to determine nidus and target volumes, as well as involved organs at risk (optical structures, inner ear, brain stem). Plans for multiple intensity-modulated arcs with a single isocenter were optimized for a fractionation of 25 Gy in 5 fractions. All plans were optimized for 6-MV photon beams. Dose-volume histograms were analyzed to assess plan quality. Deliverymore » parameters were reported to appraise technical features of RapidArc, and pretreatment quality assurance measurements were carried out to report on quality of delivery. Results: Average size of AVM nidus was 26.2 cm{sup 3}, and RapidArc plans provided complete target coverage with minimal overdosage (V{sub 100%} = 100% and V{sub 110%} < 1%) and excellent homogeneity (<6%). Organs at risk were highly spared. The D{sub 1%} to chiasm, eyes, lenses, optic nerves, and brainstem (mean {+-} SD) was 6.4 {+-} 8.3, 1.9 {+-} 3.8, 2.3 {+-} 2.2, 0.7 {+-} 0.9, 4.4 {+-} 7.2, 12.2 {+-} 9.6 Gy, respectively. Conformity index (CI{sub 95%}) was 2.2 {+-} 0.1. The number of monitor units per gray was 277 {+-} 45, total beam-on time was 2.5 {+-} 0.3 min. Planning vs. delivery {gamma} pass rate was 98.3% {+-} 0.9%. None of the patients developed acute toxicity. With a median follow-up of 9 months, 3 patients presented with deterioration of symptoms and were found to have postradiation changes but responded symptomatically to steroids. These patients continue to do well on follow-up. One patient developed headache and seizures, which was attributed to intracranial bleed, confirmed on imaging. Conclusion: Hypofractionated stereotactic radiotherapy can be successfully delivered using the RapidArc form of volumetric arc technology for intracranial AVMs. The quality of delivery and calculated parameters are in agreement with each other and are in line with published reports for other sites.« less

Total dural irradiation: RapidArc versus static-field IMRT: A case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelly, Paul J., E-mail: paulj.kelly@hse.ie; Mannarino, Edward; Lewis, John Henry

2012-07-01

The purpose of this study was to compare conventional fixed-gantry angle intensity-modulated radiation therapy (IMRT) with RapidArc for total dural irradiation. We also hypothesize that target volume-individualized collimator angles may produce substantial normal tissue sparing when planning with RapidArc. Five-, 7-, and 9-field fixed-gantry angle sliding-window IMRT plans were generated for comparison with RapidArc plans. Optimization and normal tissue constraints were constant for all plans. All plans were normalized so that 95% of the planning target volume (PTV) received at least 100% of the dose. RapidArc was delivered using 350 Degree-Sign clockwise and counterclockwise arcs. Conventional collimator angles of 45more » Degree-Sign and 315 Degree-Sign were compared with 90 Degree-Sign on both arcs. Dose prescription was 59.4 Gy in 33 fractions. PTV metrics used for comparison were coverage, V{sub 107}%, D1%, conformality index (CI{sub 95}%), and heterogeneity index (D{sub 5}%-D{sub 95}%). Brain dose, the main challenge of this case, was compared using D{sub 1}%, Dmean, and V{sub 5} Gy. Dose to optic chiasm, optic nerves, globes, and lenses was also compared. The use of unconventional collimator angles (90 Degree-Sign on both arcs) substantially reduced dose to normal brain. All plans achieved acceptable target coverage. Homogeneity was similar for RapidArc and 9-field IMRT plans. However, heterogeneity increased with decreasing number of IMRT fields, resulting in unacceptable hotspots within the brain. Conformality was marginally better with RapidArc relative to IMRT. Low dose to brain, as indicated by V5Gy, was comparable in all plans. Doses to organs at risk (OARs) showed no clinically meaningful differences. The number of monitor units was lower and delivery time was reduced with RapidArc. The case-individualized RapidArc plan compared favorably with the 9-field conventional IMRT plan. In view of lower monitor unit requirements and shorter delivery time, RapidArc was selected as the optimal solution. Individualized collimator angle solutions should be considered by RapidArc dosimetrists for OARs dose reduction. RapidArc should be considered as a treatment modality for tumors that extensively involve in the skull, dura, or scalp.« less

WE-F-304-03: Optic Nerve/Chiasm Hypofractionated SRS/SRT Dose Tolerance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milano, M.

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT’s work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe andmore » effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes. 1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60. Learning Objectives: Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures. Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation. One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data. No others have relevant conflicts of interest.« less

SU-F-T-539: Dosimetric Comparison of Volumetric Modulated Arc Therapy and Intensity Modulated Radiation Therapy for Whole Brain Hippocampal Sparing Radiation Therapy Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kendall, E; Higby, C; Algan, O

2016-06-15

Purpose: To compare the treatment plan quality and dose gradient near the hippocampus between VMAT (RapidArc) and IMRT delivery techniques for whole brain radiation therapy. Methods: Fifteen patients were evaluated in this retrospective study. All treatments were planned on Varian Eclipse TPS, using 3-Arc VMAT and 9-Field IMRT, following NRG Oncology protocol NRG-CC001 guidelines evaluated by a single radiation oncologist. Prescribed doses in all plans were 30 Gy delivered over 10 fractions normalized to a minimum of 100% of the dose covering 95% of the target volume. Identical contour sets and dose-volume constraints following protocol guidelines were also applied inmore » all plans. A paired t-test analysis was used to compare VMAT and IMRT plans. Results: NRG-CC001 protocol dose-volume constraints were met for all VMAT and IMRT plans. For the planning target volume (PTV), the average values for D2% and D98% were 6% lower and 4% higher in VMAT than in IMRT, respectively. The average mean and maximum hippocampus doses in Gy for VMAT vs IMRT plans were (11.85±0.81 vs. 12.24±0.56, p=0.10) and (16.27±0.78 vs. 16.59±0.71, p=0.24), respectively. In VMAT, the average mean and maximum chiasm doses were 3% and 1% higher than in IMRT plans, respectively. For the left optic nerve, the average mean and maximum doses were 10% and 5% higher in VMAT than in IMRT plans, respectively. These values were 12% and 3% for the right optic nerve. The average percentage of dose gradient around the hippocampus in the 0–5mm and 5–10mm abutted regions for VMAT vs. IMRT were (4.42%±2.22% /mm vs. 3.95%±2.61% /mm, p=0.43) and (4.54%±1.50% /mm vs. 4.39%±1.28% /mm, p=0.73), respectively. Conclusion: VMAT plans can achieve higher hippocampus sparing with a faster dose fall-off than IMRT plans. Though statistically insignificant, VMAT offers better PTV coverage with slightly higher doses to OARs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Amy T.Y., E-mail: changty@ha.org.hk; Hung, Albert W.M.; Cheung, Fion W.K.

Purpose: Intensity modulated radiation therapy (IMRT) is widely used to achieve a highly conformal dose and improve treatment outcome. However, plan quality and planning time are institute and planner dependent, and no standardized tool exists to recognize an optimal plan. RapidPlan, a knowledge-based algorithm, can generate constraints to assist optimization and produce high-quality IMRT plans. This report evaluated the quality and efficiency of using RapidPlan in nasopharyngeal carcinoma (NPC) IMRT planning. Methods and Materials: RapidPlan was configured using 79 radical IMRT plans for NPC; 20 consecutive NPC patients indicated for radical radiation therapy between October 2014 and May 2015 weremore » then recruited to assess its performance. The ability of RapidPlan to produce acceptable plans was evaluated. For plans that could not achieve clinical acceptance, manual touch-up was performed. The IMRT plans produced without RapidPlan (manual plans) and with RapidPlan (RP-2 plans, including those with manual touch-up) were compared in terms of dosimetric quality and planning efficiency. Results: RapidPlan by itself could produce clinically acceptable plans for 9 of the 20 patients; manual touch-up increased the number of acceptable plans (RP-2 plans) to 19. The target dose coverage and conformity were very similar. No difference was found in the maximum dose to the brainstem and optic chiasm. RP-2 plans delivered a higher maximum dose to the spinal cord (46.4 Gy vs 43.9 Gy, P=.002) but a lower dose to the parotid (mean dose to right parotid, 37.3 Gy vs 45.4 Gy; left, 34.4 Gy vs 43.1 Gy; P<.001) and the right cochlea (mean dose, 48.6 Gy vs 52.6 Gy; P=.02). The total planning time for RP-2 plans was significantly less than that for manual plans (64 minutes vs 295 minutes, P<.001). Conclusions: This study shows that RapidPlan can significantly improve planning efficiency and produce quality IMRT plans for NPC patients.« less

A modular approach to intensity-modulated arc therapy optimization with noncoplanar trajectories

NASA Astrophysics Data System (ADS)

Papp, Dávid; Bortfeld, Thomas; Unkelbach, Jan

2015-07-01

Utilizing noncoplanar beam angles in volumetric modulated arc therapy (VMAT) has the potential to combine the benefits of arc therapy, such as short treatment times, with the benefits of noncoplanar intensity modulated radiotherapy (IMRT) plans, such as improved organ sparing. Recently, vendors introduced treatment machines that allow for simultaneous couch and gantry motion during beam delivery to make noncoplanar VMAT treatments possible. Our aim is to provide a reliable optimization method for noncoplanar isocentric arc therapy plan optimization. The proposed solution is modular in the sense that it can incorporate different existing beam angle selection and coplanar arc therapy optimization methods. Treatment planning is performed in three steps. First, a number of promising noncoplanar beam directions are selected using an iterative beam selection heuristic; these beams serve as anchor points of the arc therapy trajectory. In the second step, continuous gantry/couch angle trajectories are optimized using a simple combinatorial optimization model to define a beam trajectory that efficiently visits each of the anchor points. Treatment time is controlled by limiting the time the beam needs to trace the prescribed trajectory. In the third and final step, an optimal arc therapy plan is found along the prescribed beam trajectory. In principle any existing arc therapy optimization method could be incorporated into this step; for this work we use a sliding window VMAT algorithm. The approach is demonstrated using two particularly challenging cases. The first one is a lung SBRT patient whose planning goals could not be satisfied with fewer than nine noncoplanar IMRT fields when the patient was treated in the clinic. The second one is a brain tumor patient, where the target volume overlaps with the optic nerves and the chiasm and it is directly adjacent to the brainstem. Both cases illustrate that the large number of angles utilized by isocentric noncoplanar VMAT plans can help improve dose conformity, homogeneity, and organ sparing simultaneously using the same beam trajectory length and delivery time as a coplanar VMAT plan.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruan, D; Shao, W; Low, D

Purpose: To evaluate and test the hypothesis that plan quality may be systematically affected by treatment delivery techniques and target-tocritical structure geometric relationship in radiotherapy for brain tumor. Methods: Thirty-four consecutive brain tumor patients treated between 2011–2014 were analyzed. Among this cohort, 10 were planned with 3DCRT, 11 with RadipArc, and 13 with helical IMRT on TomoTherapy. The selected dosimetric endpoints (i.e., PTV V100, maximum brainstem/chiasm/ optic nerve doses) were considered as a vector in a highdimensional space. A Pareto analysis was performed to identify the subset of Pareto-efficient plans.The geometric relationships, specifically the overlapping volume and centroid-of-mass distance betweenmore » each critical structure to the PTV were extracted as potential geometric features. The classification-tree analyses were repeated using these geometric features with and without the treatment modality as an additional categorical predictor. In both scenarios, the dominant features to prognosticate the Pareto membership were identified and the tree structures to provide optimal inference were recorded. The classification performance was further analyzed to determine the role of treatment modality in affecting plan quality. Results: Seven Pareto-efficient plans were identified based on dosimetric endpoints (3 from 3DCRT, 3 from RapicArc, 1 from Tomo), which implies that the evaluated treatment modality may have a minor influence on plan quality. Classification trees with/without the treatment modality as a predictor both achieved accuracy of 88.2%: with 100% sensitivity and 87.1% specificity for the former, and 66.7% sensitivity and 96.0% specificity for the latter. The coincidence of accuracy from both analyses further indicates no-to-weak dependence of plan quality on treatment modality. Both analyses have identified the brainstem to PTV distance as the primary predictive feature for Pareto-efficiency. Conclusion: Pareto evaluation and classification-tree analyses have indicated that plan quality depends strongly on geometry for brain tumor, specifically PTV-tobrain-stem-distance but minimally on treatment modality.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, D; Trofimov, A; Winey, B

Purpose: We developed a knowledge-based model that can predict the patient-specific benefits of proton therapy based upon geometric considerations. The model could also aid patient selection in model-based clinical trials or help justify clinical decisions to insurance companies. Methods: The knowledge-based method trains a model upon existing proton treatment plans, exploiting correlations between dose and distance-to-target. Each OAR is split into concentric subvolumes surrounding the target volume, and a skew-normal PDF is fit to the dose distribution found within each shell. The model learns from shared trends in how the best-fit skew-normal parameters depend upon distance-to-target. It can then predictmore » feasible OAR DVHs for a new patient (without a proton plan) based upon their geometry. The expected benefits of proton therapy are assessed by comparing the predicted DVHs to those of an IMRT plan, using a metric such as the equivalent uniform dose (EUD). Results: A model was trained for clival chordoma, owing to its geometric complexity and the multitude of nearby OARs. The model was trained using 20 patients and validated with a further 20 patients, and considers several different OARs. The predicted EUD was in good agreement with that of the actual proton plan. The coefficient of determination (R-squared) was 85% overall, 92% for cochleas, 80% for optic chiasm and 79% for spinal cord. The model exhibited no signs of bias or overfitting. When compared to an IMRT plan, the model could classify whether a patient will experience a gain or a loss with an accuracy between 75% and 95%, depending upon the OAR. Conclusion: We developed a model that can quickly and accurately predict the patient-specific benefits of proton therapy in clival chordoma patients, though models could be trained for other tumor sites. This work is funded by National Cancer Institute grant U19 CA 021239.« less

Alterations in diurnal rhythmicity in patients treated for nonfunctioning pituitary macroadenoma: a controlled study and literature review.

PubMed

Joustra, S D; Thijs, R D; van den Berg, R; van Dijk, M; Pereira, A M; Lammers, G J; van Someren, E J W; Romijn, J A; Biermasz, N R

2014-08-01

Patients treated for nonfunctioning pituitary macroadenomas (NFMAs) have fatigue and alterations in sleep characteristics and sleep-wake rhythmicity frequently. As NFMAs often compress the optic chiasm, these complaints might be related to dysfunction of the adjacent suprachiasmatic nucleus (SCN). We aimed to explore whether indirect indices of SCN functioning are altered in the long term after surgery for NFMAs. We studied 17 NFMA patients in long-term remission after transsphenoidal surgery, receiving adequate and stable hormone replacement for hypopituitarism, and 17 control subjects matched for age, gender, and BMI. Indirect indices of SCN function were assessed from 24-h ambulatory recordings of skin and core body temperatures, blood pressure, and salivary melatonin levels. Altered melatonin secretion was defined as an absence of evening rise, considerable irregularity, or daytime values >3 pg/ml. We additionally studied eight patients treated for craniopharyngioma. Distal-proximal skin temperature gradient did not differ between NFMAs and control subjects, but proximal skin temperature was decreased during daytime (P=0.006). Core body temperature and non-dipping of blood pressure did not differ, whereas melatonin secretion was often altered in NFMAs (OR 5.3, 95% CI 0.9-30.6). One or more abnormal parameters (≥2.0 SDS of control subjects) were observed during nighttime in 12 NFMA patients and during daytime in seven NFMA patients. Similar patterns were observed in craniopharyngioma patients. Heterogeneous patterns of altered diurnal rhythmicity in skin temperature and melatonin secretion parameters were observed in the majority of patients treated for NFMAs. On a group level, both NFMA and craniopharyngioma patients showed a lower daytime proximal skin temperature than control subjects, but other group averages were not significantly different. The observations suggest altered function of central (or peripheral) clock machinery, possibly by disturbed entrainment or damage of the hypothalamic SCN by the suprasellar macroadenoma or its treatment. © 2014 European Society of Endocrinology.

A rare challenging case of co-existent craniopharyngioma, acromegaly and squamous cell lung cancer.

PubMed

Fountas, Athanasios; Chai, Shu Teng; Ayuk, John; Gittoes, Neil; Chavda, Swarupsinh; Karavitaki, Niki

2018-01-01

Co-existence of craniopharyngioma and acromegaly has been very rarely reported. A 65-year-old man presented with visual deterioration, fatigue and frontal headaches. Magnetic resonance imaging revealed a suprasellar heterogeneous, mainly cystic, 1.9 × 2 × 1.9 cm mass compressing the optic chiasm and expanding to the third ventricle; the findings were consistent with a craniopharyngioma. Pituitary hormone profile showed hypogonadotropic hypogonadism, mildly elevated prolactin, increased insulin-like growth factor 1 (IGF-1) and normal thyroid function and cortisol reserve. The patient had transsphenoidal surgery and pathology of the specimen was diagnostic of adamantinomatous craniopharyngioma. Post-operatively, he had diabetes insipidus, hypogonadotropic hypogonadism and adrenocorticotropic hormone and thyroid-stimulating hormone deficiency. Despite the hypopituitarism, his IGF-1 levels remained elevated and subsequent oral glucose tolerance test did not show complete growth hormone (GH) suppression. Further review of the pre-operative imaging revealed a 12 × 4 mm pituitary adenoma close to the right carotid artery and no signs of pituitary hyperplasia. At that time, he was also diagnosed with squamous cell carcinoma of the left upper lung lobe finally managed with radical radiotherapy. Treatment with long-acting somatostatin analogue was initiated leading to biochemical control of the acromegaly. Latest imaging has shown no evidence of craniopharyngioma regrowth and stable adenoma. This is a unique case report of co-existence of craniopharyngioma, acromegaly and squamous lung cell carcinoma that highlights diagnostic and management challenges. Potential effects of the GH hypersecretion on the co-existent tumours of this patient are also briefly discussed. Although an extremely rare clinical scenario, craniopharyngioma and acromegaly can co-exist; aetiopathogenic link between these two conditions is unlikely.Meticulous review of unexpected biochemical findings is vital for correct diagnosis of dual pituitary pathology.The potential adverse impact of GH excess due to acromegaly in a patient with craniopharyngioma (and other neoplasm) mandates adequate biochemical control of the GH hypersecretion.

TH-EF-BRB-01: BEST IN PHYSICS (THERAPY): Dosimetric Comparison of 4π and Clinical IMRT for Cortex-Sparing High-Grade Glioma Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woods, K; Tran, A; Yu, V

Purpose: Thinning of the cerebral cortex has been observed in patients treated with fractionated partial brain radiation therapy and may contribute to cognitive decline following treatment. The extent of this thinning is dose-dependent, and was shown comparable to that of neurodegenerative diseases such as Alzheimer’s disease at one year post-therapy. This study investigates whether 4π radiotherapy can enable better sparing of the cortex and other critical structures when compared to conventional clinical IMRT plans. Methods: Clinical cortex-sparing IMRT plans for 15 high-grade glioma patients were included in this study. 4π radiotherapy plans were created for each patient with 20 intensity-modulatedmore » non-coplanar fields selected with a greedy column-generation optimization. All plans were normalized to deliver 100% of the prescribed dose to 95% of the planning target volume (PTV). The mean and maximum dose to the cerebral cortex and other organs at risk (OARs) were compared for the two plan types, as well as the conformity index (CI), homogeneity index (HI), and 50% dose spillage volume (R50). Results: The 4π plans significantly reduced the mean cortex dose by an average of 16% (range 6% to 27%) compared to the clinical plans. The mean dose to every other OAR compared was also reduced by 15% to 43%, with statistically significant reductions to the brainstem, chiasm, eyes, optic nerves, subcortical whit, and hippocampus. The average maximum doses were also reduced for 10/12 OARs. The R50 was significantly reduced with the 4π plans (>14%) and the homogeneity index was significantly improved. Conclusion: 4π enables significant sparing of the cerebral cortex when treating high-grade gliomas with fractionated partial brain radiation therapy, potentially reducing the risk of harmful dose-dependent cortical thinning. NIH R43CA183390, NIH R01CA188300, Varian Medical Systems.« less

Callosal Influence on Visual Receptive Fields Has an Ocular, an Orientation-and Direction Bias.

PubMed

Conde-Ocazionez, Sergio A; Jungen, Christiane; Wunderle, Thomas; Eriksson, David; Neuenschwander, Sergio; Schmidt, Kerstin E

2018-01-01

One leading hypothesis on the nature of visual callosal connections (CC) is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs) at the vertical midline (Berlucchi and Rizzolatti, 1968), and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a strong cardinal bias.

SU-D-BRB-01: A Predictive Planning Tool for Stereotactic Radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palefsky, S; Roper, J; Elder, E

Purpose: To demonstrate the feasibility of a predictive planning tool which provides SRS planning guidance based on simple patient anatomical properties: PTV size, PTV shape and distance from critical structures. Methods: Ten framed SRS cases treated at Winship Cancer Institute of Emory University were analyzed to extract data on PTV size, sphericity (shape), and distance from critical structures such as the brainstem and optic chiasm. The cases consisted of five pairs. Each pair consisted of two cases with a similar diagnosis (such as pituitary adenoma or arteriovenous malformation) that were treated with different techniques: DCA, or IMRS. A Naive Bayesmore » Classifier was trained on this data to establish the conditions under which each treatment modality was used. This model was validated by classifying ten other randomly-selected cases into DCA or IMRS classes, calculating the probability of each technique, and comparing results to the treated technique. Results: Of the ten cases used to validate the model, nine had their technique predicted correctly. The three cases treated with IMRS were all identified as such. Their probabilities of being treated with IMRS ranged between 59% and 100%. Six of the seven cases treated with DCA were correctly classified. These probabilities ranged between 51% and 95%. One case treated with DCA was incorrectly predicted to be an IMRS plan. The model’s confidence in this case was 91%. Conclusion: These findings indicate that a predictive planning tool based on simple patient anatomical properties can predict the SRS technique used for treatment. The algorithm operated with 90% accuracy. With further validation on larger patient populations, this tool may be used clinically to guide planners in choosing an appropriate treatment technique. The prediction algorithm could also be adapted to guide selection of treatment parameters such as treatment modality and number of fields for radiotherapy across anatomical sites.« less

Serotonin immunoreactive interneurons in the brain of the Remipedia: new insights into the phylogenetic affinities of an enigmatic crustacean taxon

PubMed Central

2012-01-01

Background Remipedia, a group of homonomously segmented, cave-dwelling, eyeless arthropods have been regarded as basal crustaceans in most early morphological and taxonomic studies. However, molecular sequence information together with the discovery of a highly differentiated brain led to a reconsideration of their phylogenetic position. Various conflicting hypotheses have been proposed including the claim for a basal position of Remipedia up to a close relationship with Malacostraca or Hexapoda. To provide new morphological characters that may allow phylogenetic insights, we have analyzed the architecture of the remipede brain in more detail using immunocytochemistry (serotonin, acetylated α-tubulin, synapsin) combined with confocal laser-scanning microscopy and image reconstruction techniques. This approach allows for a comprehensive neuroanatomical comparison with other crustacean and hexapod taxa. Results The dominant structures of the brain are the deutocerebral olfactory neuropils, which are linked by the olfactory globular tracts to the protocerebral hemiellipsoid bodies. The olfactory globular tracts form a characteristic chiasm in the center of the brain. In Speleonectes tulumensis, each brain hemisphere contains about 120 serotonin immunoreactive neurons, which are distributed in distinct cell groups supplying fine, profusely branching neurites to 16 neuropilar domains. The olfactory neuropil comprises more than 300 spherical olfactory glomeruli arranged in sublobes. Eight serotonin immunoreactive neurons homogeneously innervate the olfactory glomeruli. In the protocerebrum, serotonin immunoreactivity revealed several structures, which, based on their position and connectivity resemble a central complex comprising a central body, a protocerebral bridge, W-, X-, Y-, Z-tracts, and lateral accessory lobes. Conclusions The brain of Remipedia shows several plesiomorphic features shared with other Mandibulata, such as deutocerebral olfactory neuropils with a glomerular organization, innervations by serotonin immunoreactive interneurons, and connections to protocerebral neuropils. Also, we provided tentative evidence for W-, X-, Y-, Z-tracts in the remipedian central complex like in the brain of Malacostraca, and Hexapoda. Furthermore, Remipedia display several synapomorphies with Malacostraca supporting a sister group relationship between both taxa. These homologies include a chiasm of the olfactory globular tract, which connects the olfactory neuropils with the lateral protocerebrum and the presence of hemiellipsoid bodies. Even though a growing number of molecular investigations unites Remipedia and Cephalocarida, our neuroanatomical comparison does not provide support for such a sister group relationship. PMID:22947030

SU-E-T-183: Feasibility of Extreme Dose Escalation for Glioblastoma Multiforme Using 4π Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, D; Rwigema, J; Yu, V

Purpose: GBM recurrence primarily occurs inside or near the high-dose radiation field of original tumor site requiring greater than 100 Gy to significantly improve local control. We utilize 4π non-coplanar radiotherapy to test the feasibility of planning target volume (PTV) margin expansions or extreme dose escalations without incurring additional radiation toxicities. Methods: 11 GBM patients treated with VMAT to a prescription dose of 59.4 Gy or 60 Gy were replanned with 4π. Original VMAT plans were created with 2 to 4 coplanar or non-coplanar arcs using 3 mm hi-res MLC. The 4π optimization, using 5 mm MLC, selected and inversemore » optimized 30 beams from a candidate pool of 1162 beams evenly distributed through 4π steradians. 4π plans were first compared to clinical plans using the same prescription dose. Two more studies were then performed to respectively escalate the GTV and PTV doses to 100 Gy, followed by a fourth plan expanding the PTV by 5 mm and maintaining the prescription dose. Results: The standard 4π plan significantly reduced (p<0.01) max and mean doses to critical structures by a range of 47.0–98.4% and 61.0–99.2%, respectively. The high dose PTV/high dose GTV/expanded PTV studies showed a reduction (p<0.05) or unchanged* (p>0.05) maximum dose of 72.1%/86.7%/77.1% (chiasm), 7.2%*/27.7%*/30.7% (brainstem), 39.8%*/84.2%/51.9%* (spinal cord), 69.0%/87.0%/66.9% (L eye), 76.2%/88.1%/84.1% (R eye), 95.0%/98.6%/97.5% (L lens), 93.9%/98.8%/97.6% (R lens), 74.3%/88.5%/72.4% (L optical nerve), 80.4%/91.3%/75.7% (R optical nerve), 64.8%/84.2%/44.9%* (L cochlea), and 85.2%/93.0%/78.0% (R cochlea), respectively. V30 and V36 for both brain and (brain - PTV) were reduced for all cases except the high dose PTV plan. PTV dose coverage increased for all 4π plans. Conclusion: Extreme dose escalation or further margin expansion is achievable using 4π, maintaining or reducing OAR doses. This study indicates that clinical trials employing 4π delivery using prescription doses up to 100 Gy are feasible. Funding support partially contributed by Varian.« less

Multimodal Navigation in Endoscopic Transsphenoidal Resection of Pituitary Tumors using Image-based Vascular and Cranial Nerve Segmentation: A Prospective Validation Study

PubMed Central

Dolati, Parviz; Eichberg, Daniel; Golby, Alexandra; Zamani, Amir; Laws, Edward

2016-01-01

Introduction Transsphenoidal surgery (TSS) is a well-known approach for the treatment of pituitary tumors. However, lateral misdirection and vascular damage, intraoperative CSF leakage, and optic nerve and vascular injuries are all well-known complications, and the risk of adverse events is more likely in less experienced hands. This prospective study was conducted to validate the accuracy of image-based segmentation in localization of neurovascular structures during TSS. Methods Twenty-five patients with pituitary tumors underwent preoperative 3TMRI, which included thin-sectioned 3D space T2, 3D Time of Flight and MPRAGE sequences. Images were reviewed by an expert independent neuroradiologist. Imaging sequences were loaded in BrainLab iPlanNet (16/25 cases) or Stryker (9/25 cases) image guidance platforms for segmentation and pre-operative planning. After patient registration into the neuronavigation system and subsequent surgical exposure, each segmented neural or vascular element was validated by manual placement of the navigation probe on or as close as possible to the target. The audible pulsations of the bilateral ICA were confirmed using a micro-Doppler probe. Results Pre-operative segmentation of the ICA and cavernous sinus matched with the intra-operative endoscopic and micro-Doppler findings in all cases (Dice Similarity Coefficient =1). This information reassured the surgeons with regard to the lateral extent of bone removal at the sellar floor and the limits of lateral exploration. Excellent correspondence between image-based segmentation and the endoscopic view was also evident at the surface of the tumor and at the tumor-normal gland interfaces. This assisted in preventing unnecessary removal of the normal pituitary gland. Image-guidance assisted the surgeons in localizing the optic nerve and chiasm in 64% of the cases and the diaphragma sella in 52% of cases, which helped to determine the limits of upward exploration and to decrease the risk of CSF leakage. The accuracy of the measurements was 1.20 + 0.21 mm (mean +/−SD). Conclusion Image-based pre-operative vascular and neural element segmentation, especially with 3D reconstruction, is highly informative preoperatively and potentially could assist less experienced neurosurgeons in preventing vascular and neural injury during TSS. Additionally, the accuracy found in this study is comparable to previously reported neuronavigation measurements. This novel preliminary study is encouraging for future prospective intraoperative validation with larger numbers of patients. PMID:27302558

Helical tomotherapy with dynamic running-start-stop delivery compared to conventional tomotherapy delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rong, Yi, E-mail: yi.rong@osumc.edu; Chen, Yu; Lu, Weiguo

Purpose: Despite superior target dose uniformity, helical tomotherapy{sup ®} (HT) may involve a trade-off between longitudinal dose conformity and beam-on time (BOT), due to the limitation of only three available jaw sizes with the conventional HT (1.0, 2.5, and 5.0 cm). The recently introduced dynamic running-start-stop (RSS) delivery allows smaller jaw opening at the superior and inferior ends of the target when a sharp penumbra is needed. This study compared the dosimetric performance of RSS delivery with the fixed jaw HT delivery. Methods: Twenty patient cases were selected and deidentified prior to treatment planning, including 16 common clinical cases (brain,more » head and neck (HN), lung, and prostate) and four special cases of whole brain with hippocampus avoidance (WBHA) that require a high degree of dose modulation. HT plans were generated for common clinical cases using the fixed 2.5 cm jaw width (HT2.5) and WBHA cases using 1.0 cm (HT1.0). The jaw widths for RSS were preset with a larger size (RSS5.0 vs HT2.5 and RSS2.5 vs HT1.0). Both delivery techniques were planned based on identical contours, prescriptions, and planning objectives. Dose indices for targets and critical organs were compared using dose-volume histograms, BOT, and monitor units. Results: The average BOT was reduced from 4.8 min with HT2.5 to 2.5 min with RSS5.0. Target dose homogeneity with RSS5.0 was shown comparable to HT2.5 for common clinical sites. Superior normal tissue sparing was observed in RSS5.0 for optic nerves and optic chiasm in brain and HN cases. RSS5.0 demonstrated improved dose sparing for cord and esophagus in lung cases, as well as penile bulb in prostate cases. The mean body dose was comparable for both techniques. For the WBHA cases, the target homogeneity was significantly degraded in RSS2.5 without distinct dose sparing for hippocampus, compared to HT1.0. Conclusions: Compared to the fixed jaw HT delivery, RSS combined with a larger jaw width provides faster treatment delivery and improved cranial-caudal target dose conformity. The target coverage achieved by RSS with a large jaw width is comparable to the fixed jaw HT delivery for common cancer sites, but may deteriorate for cases where complex geometry is present in the middle part of the target.« less

Olfactory projection neuron pathways in two species of marine Isopoda (Peracarida, Malacostraca, Crustacea).

PubMed

Stemme, Torben; Eickhoff, René; Bicker, Gerd

2014-08-01

The neuroanatomy of the olfactory pathway has been intensely studied in many representatives of Malacostraca. Nevertheless, the knowledge about bilateral olfactory integration pathways is mainly based on Decapoda. Here, we investigated the olfactory projection neuron pathway of two marine isopod species, Saduria entomon and Idotea emarginata, by lipophilic dye injections into the olfactory neuropil. We show that both arms of the olfactory globular tract form a chiasm in the center of the brain, as known from several other crustaceans. Furthermore, the olfactory projection neurons innervate both the medulla terminalis and the hemiellipsoid body of the ipsi- and the contralateral hemisphere. Both protocerebral neuropils are innervated to a comparable extent. This is reminiscent of the situation in the basal decapod taxon Dendrobranchiata. Thus, we propose that an innervation by the olfactory globular tract of both the medulla terminalis and the hemiellipsoid body is characteristic of the decapod ground pattern, but also of the ground pattern of Caridoida. Copyright © 2014 Elsevier Ltd. All rights reserved.

SU-F-T-613: Multi-Lesion Cranial SRS VMAT Plan Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ballangrud, A; Kuo, L; Happersett, L

Purpose: Cranial SRS VMAT plans must have steep dose gradient around each target to reduce dose to normal brain. This study reports on the correlation between gradient index (GI=V50%/V100%), target size and target dose heterogeneity index (HI=PTV Dmax/prescription dose) for multi-lesion cranial SRS VMAT plans. Methods: VMAT plans for 10 cranial cases with 3 to 6 lesions (total 39 lesions) generated in Varian Eclipse V11.0.47 with a fine-tuned AAA beam model and 0.125 cm dose grid were analyzed. One or two iso centers were used depending on the spatial distribution of lesions. Two to nine coplanar and non-coplanar arcs weremore » used per isocenter. Conformity index (CI= V100%/VPTV), HI, and GI were determined for each lesion. Dose to critical structures were recorded. Results: Lesion size ranged from 0.05–11.00 cm3. HI ranged from 1.2–1.4, CI ranged from 1.0–2.8 and GI from 3.1–8.4. Maximum dose to brainstem, chiasm, lenses, optic nerves and eyes ranged from 120–1946 cGy, 47–463 cGy, 9–121 cGy, 14–512 cGy, and 17–294 cGy, respectively. Brain minus PTV (Brain-PTV) V7Gy was in the range 1.1–6.5%, and Brain-PTV Dmean was in the range 94–324 cGy. Conclusion: This work shows that a GI < 5 can be achieved for lesions > 0.4cc. For smaller lesions, GI increases rapidly. GI is lower when HI is increased. Based on this study, recommend HI is 1.4, and recommended GI is for volumes <0.1cc GI<9, 0.1–0.4cc GI<6, 0.4–0.1.0cc GI<5, and for volumes >1.0cc GI<4. CI is < 1.3 for all lesions except for targets < 0.1cc. Cranial SRS VMAT plans must be optimized to lower the GI to reduce the dose to normal brain tissue.« less

Linear energy transfer incorporated intensity modulated proton therapy optimization

NASA Astrophysics Data System (ADS)

Cao, Wenhua; Khabazian, Azin; Yepes, Pablo P.; Lim, Gino; Poenisch, Falk; Grosshans, David R.; Mohan, Radhe

2018-01-01

The purpose of this study was to investigate the feasibility of incorporating linear energy transfer (LET) into the optimization of intensity modulated proton therapy (IMPT) plans. Because increased LET correlates with increased biological effectiveness of protons, high LETs in target volumes and low LETs in critical structures and normal tissues are preferred in an IMPT plan. However, if not explicitly incorporated into the optimization criteria, different IMPT plans may yield similar physical dose distributions but greatly different LET, specifically dose-averaged LET, distributions. Conventionally, the IMPT optimization criteria (or cost function) only includes dose-based objectives in which the relative biological effectiveness (RBE) is assumed to have a constant value of 1.1. In this study, we added LET-based objectives for maximizing LET in target volumes and minimizing LET in critical structures and normal tissues. Due to the fractional programming nature of the resulting model, we used a variable reformulation approach so that the optimization process is computationally equivalent to conventional IMPT optimization. In this study, five brain tumor patients who had been treated with proton therapy at our institution were selected. Two plans were created for each patient based on the proposed LET-incorporated optimization (LETOpt) and the conventional dose-based optimization (DoseOpt). The optimized plans were compared in terms of both dose (assuming a constant RBE of 1.1 as adopted in clinical practice) and LET. Both optimization approaches were able to generate comparable dose distributions. The LET-incorporated optimization achieved not only pronounced reduction of LET values in critical organs, such as brainstem and optic chiasm, but also increased LET in target volumes, compared to the conventional dose-based optimization. However, on occasion, there was a need to tradeoff the acceptability of dose and LET distributions. Our conclusion is that the inclusion of LET-dependent criteria in the IMPT optimization could lead to similar dose distributions as the conventional optimization but superior LET distributions in target volumes and normal tissues. This may have substantial advantages in improving tumor control and reducing normal tissue toxicities.

Comparison of Planning Quality and Efficiency Between Conventional and Knowledge-based Algorithms in Nasopharyngeal Cancer Patients Using Intensity Modulated Radiation Therapy.

PubMed

Chang, Amy T Y; Hung, Albert W M; Cheung, Fion W K; Lee, Michael C H; Chan, Oscar S H; Philips, Helen; Cheng, Yung-Tang; Ng, Wai-Tong

2016-07-01

Intensity modulated radiation therapy (IMRT) is widely used to achieve a highly conformal dose and improve treatment outcome. However, plan quality and planning time are institute and planner dependent, and no standardized tool exists to recognize an optimal plan. RapidPlan, a knowledge-based algorithm, can generate constraints to assist optimization and produce high-quality IMRT plans. This report evaluated the quality and efficiency of using RapidPlan in nasopharyngeal carcinoma (NPC) IMRT planning. RapidPlan was configured using 79 radical IMRT plans for NPC; 20 consecutive NPC patients indicated for radical radiation therapy between October 2014 and May 2015 were then recruited to assess its performance. The ability of RapidPlan to produce acceptable plans was evaluated. For plans that could not achieve clinical acceptance, manual touch-up was performed. The IMRT plans produced without RapidPlan (manual plans) and with RapidPlan (RP-2 plans, including those with manual touch-up) were compared in terms of dosimetric quality and planning efficiency. RapidPlan by itself could produce clinically acceptable plans for 9 of the 20 patients; manual touch-up increased the number of acceptable plans (RP-2 plans) to 19. The target dose coverage and conformity were very similar. No difference was found in the maximum dose to the brainstem and optic chiasm. RP-2 plans delivered a higher maximum dose to the spinal cord (46.4 Gy vs 43.9 Gy, P=.002) but a lower dose to the parotid (mean dose to right parotid, 37.3 Gy vs 45.4 Gy; left, 34.4 Gy vs 43.1 Gy; P<.001) and the right cochlea (mean dose, 48.6 Gy vs 52.6 Gy; P=.02). The total planning time for RP-2 plans was significantly less than that for manual plans (64 minutes vs 295 minutes, P<.001). This study shows that RapidPlan can significantly improve planning efficiency and produce quality IMRT plans for NPC patients. Copyright © 2016 Elsevier Inc. All rights reserved.

TH-CD-206-05: Machine-Learning Based Segmentation of Organs at Risks for Head and Neck Radiotherapy Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibragimov, B; Pernus, F; Strojan, P

Purpose: Accurate and efficient delineation of tumor target and organs-at-risks is essential for the success of radiotherapy. In reality, despite of decades of intense research efforts, auto-segmentation has not yet become clinical practice. In this study, we present, for the first time, a deep learning-based classification algorithm for autonomous segmentation in head and neck (HaN) treatment planning. Methods: Fifteen HN datasets of CT, MR and PET images with manual annotation of organs-at-risk (OARs) including spinal cord, brainstem, optic nerves, chiasm, eyes, mandible, tongue, parotid glands were collected and saved in a library of plans. We also have ten super-resolution MRmore » images of the tongue area, where the genioglossus and inferior longitudinalis tongue muscles are defined as organs of interest. We applied the concepts of random forest- and deep learning-based object classification for automated image annotation with the aim of using machine learning to facilitate head and neck radiotherapy planning process. In this new paradigm of segmentation, random forests were used for landmark-assisted segmentation of super-resolution MR images. Alternatively to auto-segmentation with random forest-based landmark detection, deep convolutional neural networks were developed for voxel-wise segmentation of OARs in single and multi-modal images. The network consisted of three pairs of convolution and pooing layer, one RuLU layer and a softmax layer. Results: We present a comprehensive study on using machine learning concepts for auto-segmentation of OARs and tongue muscles for the HaN radiotherapy planning. An accuracy of 81.8% in terms of Dice coefficient was achieved for segmentation of genioglossus and inferior longitudinalis tongue muscles. Preliminary results of OARs regimentation also indicate that deep-learning afforded an unprecedented opportunities to improve the accuracy and robustness of radiotherapy planning. Conclusion: A novel machine learning framework has been developed for image annotation and structure segmentation. Our results indicate the great potential of deep learning in radiotherapy treatment planning.« less

Xanthogranulomatous hypophysitis: a rare and often mistaken pituitary lesion

PubMed Central

Gopal-Kothandapani, Jaya Sujatha; Bagga, Veejay; Wharton, Stephen B; Connolly, Daniel J; Sinha, Saurabh

2015-01-01

Summary Xanthogranulomatous hypophysitis (XGH) is a very rare form of pituitary hypophysitis that may present both clinically and radiologically as a neoplastic lesion. It may either be primary with an autoimmune aetiology and can occur in isolation or as a part of autoimmune systemic disease or secondary as a reactive degenerative response to an epithelial lesion (e.g. craniopharyngioma (CP), Rathke's cleft cyst, germinoma and pituitary adenomas) or as a part of a multiorgan systemic involvement such as tuberculosis, sarcoidosis or granulomatosis. It may also present with a variation of symptoms in children and adults. Our case series compares the paediatric and adult presentations of XGH and the differential diagnoses considered in one child and two adult patients, highlighting the wide spectrum of this condition. Endocrine investigations suggested panhypopituitarism in all three patients and imaging revealed a suprasellar mass compressing the optic chiasm suggestive of CP or Rathke's cleft cyst in one patient and non-functioning pituitary macroadenoma in two patients. Magnetic resonance imaging (MRI) demonstrated mixed signal intensities on T1- and T2-weighted sequences. Following endoscopic transsphenoidal surgery, histological analysis revealed necrotic material with a xanthogranulomatous reaction confirming XGH in two patients and a necrobiotic granulomatous chronic inflammatory infiltrate with neutrophils in one patient, which is not typical of current descriptions of this disorder. This case series describes the wide spectrum of XGH disease that is yet to be defined. Mixed signal intensities on T1- and T2-weighted MRI sequences may indicate XGH and diagnosis is confirmed by histology. Histological variation may indicate an underlying systemic process. Learning points XGH is a rare form of pituitary hypophysitis with a wide clinical and histological spectrum and can mimic a neoplastic lesion.XGH primarily presents with growth arrest in children and pubertal arrest in adolescents. In adults, the presentation may vary.A combination of hypopituitarism and mixed signal intensity lesion on MRI is suggestive of XGH and should be considered in the differential diagnosis of sellar lesions.Radical surgery is the treatment of choice and carries an excellent prognosis with no recurrence. PMID:25759759

SU-F-T-388: Comparison of Biophysical Indices in Hippocampal-Avoidance Whole Brain VMAT and IMRT Radiation Therapy Treatment Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kendall, E; Ahmad, S; Algan, O

2016-06-15

Purpose: To compare biophysical indices of Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT) treatment plans for whole brain radiation therapy following the NRG-CC001 protocol. Methods: In this retrospective study, a total of fifteen patients were planned with Varian Eclipse Treatment Planning System using VMAT (RapidArc) and IMRT techniques. The planning target volume (PTV) was defined as the whole brain volume excluding a uniform three-dimensional 5mm expansion of the hippocampus volume. Prescribed doses in all plans were 30 Gy delivered over 10 fractions normalized to a minimum of 95% of the target volume receiving 100% of themore » prescribed dose. The NRG Oncology protocol guidelines were followed for contouring and dose-volume constraints. A single radiation oncologist evaluated all treatment plans. Calculations of statistical significance were performed using Student’s paired t-test. Results: All VMAT and IMRT plans met the NRG-CC001 protocol dose-volume criteria. The average equivalent uniform dose (EUD) for the PTV for VMAT vs. IMRT was respectively (19.05±0.33 Gy vs. 19.38±0.47 Gy) for α/β of 2 Gy and (19.47±0.30 Gy vs. 19.84±0.42 Gy) for α/β of 10 Gy. For the PTV, the average mean and maximum doses were 2% and 5% lower in VMAT plans than in IMRT plans, respectively. The average EUD and the normal tissue complication probability (NTCP) for the hippocampus in VMAT vs. IMRT plans were (15.28±1.35 Gy vs. 15.65±0.99 Gy, p=0.18) and (0.305±0.012 Gy vs. 0.308±0.008 Gy, p=0.192), respectively. The average EUD and NTCP for the optic chiasm were both 2% higher in VMAT than in IMRT plans. Conclusion: Though statistically insignificant, VMAT plans indicate a lower hippocampus EUD than IMRT plans. Also, a small variation in NTCP was found between plans.« less

SU-E-T-395: Evaluation of Multiple Brain Metastases Stereotactic Treatment Planning in Cyberknife Versus Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vikraman, S; Rajesh, Thiyagarajan; Karrthick, Kp

2015-06-15

Purpose: The purpose of this study was to evaluate multiple brain metastases stereotactic treatment planning of Cyberknife versus linac using dose volume based indices. Methods: Fifteen multiple brain metastases patients were taken for this study from Cyberknife Multiplan TPSv4.6.0. All these patients underwent stereotactic treatment in Cyberknife. For each patient VMAT stereotactic treatment plan was generated in MONACO TPSv5.0 using Elekta beam modulator MLC and matched the delivered plan. A median dose of 8.5Gy(range 7–12Gy) per fraction was prescribed. Tumor volume was in the range of 0.06–4.33cc. Treatment plan quality was critically evaluated by comparing DVH indices such as D98,more » D95, CI, and HI for target volumes. Maximum point doses and volume doses were evaluated for critical organs. Results: For each case, target coverage of D98 was achieved with 100% prescription dose with SD of 0.29% and 0.41% in Linac and Cyberknife respectively. The average conformity index(CI) of 1.26±0.0796 SD for Cyberknife and 1.92±0.60SD for linac were observed. Better homogeneity Index (HI) of 1.17±0.09SD was observed in linac as compared to Cyberknife HI of 1.24±0.05SD.All the critical organ doses were well within tolerance limit in both linac and Cyberknife plans. There is no significant difference of maximum point doses for brainstem and optic chiasm. Treatment time and number of monitor units are more in Cyberknife compared to linac. The average volume receiving 12Gy in whole brain was 6% and 12% for Cyberknife and linac respectively. 1000cc of whole brain received 60% lesser dose in Linac compared to Cyberknife in all cases. Conclusion: The study shows that dosimetrically comparable plans are achievable Cyberknife and Linac. However, a better conformity, target coverage, lesser OAR dose is achieved with Cyberknife due to greater degrees of freedom with robotic gantry and smaller collimator for multiple targets.« less

SU-E-T-587: Optimal Volumetric Modulated Arc Radiotherapy Treatment Planning Technique for Multiple Brain Metastases with Increasing Number of Arcs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keeling, V; Hossain, S; Hildebrand, K

Purpose: To show improvements in dose conformity and normal brain tissue sparing using an optimal planning technique (OPT) against clinically acceptable planning technique (CAP) in the treatment of multiple brain metastases. Methods: A standardized international benchmark case with12 intracranial tumors was planned using two different VMAT optimization methods. Plans were split into four groups with 3, 6, 9, and 12 targets each planned with 3, 5, and 7 arcs using Eclipse TPS. The beam geometries were 1 full coplanar and half non-coplanar arcs. A prescription dose of 20Gy was used for all targets. The following optimization criteria was used (OPTmore » vs. CAP): (No upper limit vs.108% upper limit for target volume), (priority 140–150 vs. 75–85 for normal-brain-tissue), and (selection of automatic sparing Normal-Tissue-Objective (NTO) vs. Manual NTO). Both had priority 50 to critical structures such as brainstem and optic-chiasm, and both had an NTO priority 150. Normal-brain-tissue doses along with Paddick Conformity Index (PCI) were evaluated. Results: In all cases PCI was higher for OPT plans. The average PCI (OPT,CAP) for all targets was (0.81,0.64), (0.81,0.63), (0.79,0.57), and (0.72,0.55) for 3, 6, 9, and 12 target plans respectively. The percent decrease in normal brain tissue volume (OPT/CAP*100) achieved by OPT plans was (reported as follows: V4, V8, V12, V16, V20) (184, 343, 350, 294, 371%), (192, 417, 380, 299, 360%), and (235, 390, 299, 281, 502%) for the 3, 5, 7 arc 12 target plans, respectively. The maximum brainstem dose decreased for the OPT plan by 4.93, 4.89, and 5.30 Gy for 3, 5, 7 arc 12 target plans, respectively. Conclusion: Substantial increases in PCI, critical structure sparing, and decreases in normal brain tissue dose were achieved by eliminating upper limits from optimization, using automatic sparing of normal tissue function with high priority, and a high priority to normal brain tissue.« less

A treatment planning comparison between a novel rotating gamma system and robotic linear accelerator based intracranial stereotactic radiosurgery/radiotherapy

NASA Astrophysics Data System (ADS)

Fareed, Muhammad M.; Eldib, Ahmed; Weiss, Stephanie E.; Hayes, Shelly B.; Li, Jinsheng; C-M Ma, Charlie

2018-02-01

To compare the dosimetric parameters of a novel rotating gamma ray system (RGS) with well-established CyberKnife system (CK) for treating malignant brain lesions. RGS has a treatment head of 16 cobalt-60 sources focused to the isocenter, which can rotate 360° on the ring gantry and swing 35° in the superior direction. We compared several dosimetric parameters in 10 patients undergoing brain stereotactic radiosurgery including plan normalization, number of beams and nodes for CK and shots for RGS, collimators used, estimated treatment time, D 2 cm and conformity index (CI) among two modalities. The median plan normalization for RGS was 56.7% versus 68.5% (p  =  0.002) for CK plans. The median number of shots from RGS was 7.5 whereas the median number of beams and nodes for CK was 79.5 and 46. The median collimator’s diameter used was 3.5 mm for RGS as compared to 5 mm for CK (p  =  0.26). Mean D 2 cm was 5.57 Gy for CyberKnife whereas it was 3.11 Gy for RGS (p  =  0.99). For RGS plans, the median CI was 1.4 compared to 1.3 for the CK treatment plans (p  =  0.98). The average minimum and maximum doses to optic chiasm were 21 and 93 cGy for RGS as compared to 32 and 209 cGy for CK whereas these were 0.5 and 364 cGy by RGS and 18 and 399 cGy by CK to brainstem. The mean V12 Gy for brain predicting for radionecrosis with RGS was 3.75 cm3 as compared to 4.09 cm3 with the CK (p  =  0.41). The dosimetric parameters of a novel RGS with a ring type gantry are comparable with CyberKnife, allowing its use for intracranial lesions and is worth exploring in a clinical setting.

Computerized tomography versus magnetic resonance imaging: a comparative study in hypothalamic-pituitary and parasellar pathology.

PubMed

Webb, S M; Ruscalleda, J; Schwarzstein, D; Calaf-Alsina, J; Rovira, A; Matos, G; Puig-Domingo, M; de Leiva, A

1992-05-01

We wished to analyse the relative value of computerized tomography and magnetic resonance in patients referred for evaluation of pituitary and parasellar lesions. We performed a separate evaluation by two independent neuroradiologists of computerized tomography and magnetic resonance images ordered numerically and anonymously, with no clinical data available. We studied 40 patients submitted for hypothalamic-pituitary study; 31 were carried out preoperatively, of which histological confirmation later became available in 14. The remaining nine patients were evaluated postoperatively. Over 40 parameters relating to the bony margins, cavernous sinuses, carotid arteries, optic chiasm, suprasellar cisterns, pituitary, pituitary stalk and extension of the lesion were evaluated. These reports were compared with the initial ones offered when the scans were ordered, and with the final diagnosis. Concordance between initial computerized tomography and magnetic resonance was observed in 27 cases (67.5%); among the discordant cases computerized tomography showed the lesion in two, magnetic resonance in 10, while in the remaining case reported to harbour a microadenoma on computerized tomography the differential diagnosis between a true TSH-secreting microadenoma and pituitary resistance to thyroid hormones is still unclear. Both neuroradiologists coincided in their reports in 32 patients (80%); when the initial report was compared with those of the neuroradiologists, concordance was observed with at least one of them in 34 instances (85%). Discordant results were observed principally in microadenomas secreting ACTH or PRL and in delayed puberty. In the eight patients with Cushing's disease (histologically confirmed in six) magnetic resonance was positive in five and computerized tomography in two; the abnormal image correctly identified the side of the lesion at surgery. In patients referred for evaluation of Cushing's syndrome or hyperprolactinaemia (due to microadenomas) or after surgery, magnetic resonance is clearly preferable to computerized tomography. In macroadenomas both scans are equally diagnostic but magnetic resonance offers more information on pituitary morphology and neighbouring structures. Nevertheless, there are cases in which the results of computerized tomography and magnetic resonance will complement each other, since different parameters are analysed with each examination and discordant results are encountered.

The suprachiasmatic nucleus in the sheep: retinal projections and cytoarchitectural organization.

PubMed

Tessonneaud, A; Cooper, H M; Caldani, M; Locatelli, A; Viguier-Martinez, M C

1994-10-01

The retinal innervation, cytoarchitectural, and immunohistochemical organization of the suprachiasmatic nucleus (SCN) was studied in the domestic sheep. The SCN is a large elongated nucleus extending rostrocaudally for roughly 3 mm in the hypothalamus. The morphology is unusual in that the rostral part of the nucleus extends out of the main mass of the hypothalamus onto the dorsal aspect of the optic chiasm. Following intraocular injection of wheat-germ agglutinin-horseradish peroxidase or tritiated amino acids, anterograde label is distributed throughout the SCN. Retinal innervation of the SCN is bilaterally symmetric or predominantly ipsilateral. Quantitative image analysis demonstrates that, although the amount of autoradiographic label is greatest in the ventral and central parts of the nucleus, density varies progressively between different regions. In addition to the SCN, retinal fibers are also seen in the medial preoptic area, the anterior and lateral hypothalamic area, the dorsomedial hypothalamus, the retrochiasmatic area, and the basal telencephalon. Whereas the SCN can be identified using several techniques, complete delineation of the nucleus requires combined tract tracing, cytoarchitectural, and histochemical criteria. Compared with the surrounding hypothalamic regions, the SCN contains smaller, more densely packed neurons, and is largely devoid of myelinated fibers. Cell soma sizes are smaller in the ventral SCN than in the dorsal or lateral parts, but an obvious regional transition is lacking. Using Nissl, myelin, acetylcholinesterase, and cytochrome oxidase staining, the SCN can be clearly distinguished in the rostral and medial regions, but is less differentiated toward the caudal pole. Immunohistochemical demonstration of several neuropeptides shows that the neurochemical organization of the sheep SCN is heterogeneous, but that it lacks a distinct compartmental organization. Populations of different neuropeptide-containing cells are found throughout the nucleus, although perikarya positive for vasoactive intestinal polypeptide and fibers labeled for methionine-enkephalin are predominant ventrally; neurophysin-immunoreactive cells are more prominent in the dorsal region and toward the caudal pole. The results suggest that the intrinsic organization of the sheep SCN is characterized by gradual regional transitions between different zones.

Critical appraisal of RapidArc radiosurgery with flattening filter free photon beams for benign brain lesions in comparison to GammaKnife: a treatment planning study.

PubMed

Abacioglu, Ufuk; Ozen, Zeynep; Yilmaz, Meltem; Arifoglu, Alptekin; Gunhan, Basri; Kayalilar, Namik; Peker, Selcuk; Sengoz, Meric; Gurdalli, Salih; Cozzi, Luca

2014-05-21

To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique. Twelve patients with vestibular schwannoma (VS, n = 6) or cavernous sinus meningioma (CSM, n = 6) were planned for both SRS using volumetric modulated arc therapy (VMAT) by RA. 104 MV flattening filter free photon beams with a maximum dose rate of 2400 MU/min were selected. Data were compared against plans optimised for GK. A single dose of 12.5 Gy was prescribed. The primary objective was to assess treatment plan quality. Secondary aim was to appraise treatment efficiency. For VS, comparing best GK vs. RA plans, homogeneity was 51.7 ± 3.5 vs. 6.4 ± 1.5%; Paddick conformity Index (PCI) resulted 0.81 ± 0.03 vs. 0.84 ± 0.04. Gradient index (PGI) was 2.7 ± 0.2 vs. 3.8 ± 0.6. Mean target dose was 17.1 ± 0.9 vs. 12.9 ± 0.1 Gy. For the brain stem, D(1cm3) was 5.1 ± 2.0 Gy vs 4.8 ± 1.6 Gy. For the ipsilateral cochlea, D(0.1cm3) was 1.7 ± 1.0 Gy vs. 1.8 ± 0.5 Gy. For CSM, homogeneity was 52.3 ± 2.4 vs. 12.4 ± 0.6; PCI: 0.86 ± 0.05 vs. 0.88 ± 0.05; PGI: 2.6 ± 0.1 vs. 3.8 ± 0.5; D(1cm3) to brain stem was 5.4 ± 2.8 Gy vs. 5.2 ± 2.8 Gy; D(0.1cm3) to ipsi-lateral optic nerve was 4.2 ± 2.1 vs. 2.1 ± 1.5 Gy; D(0.1cm3) to optic chiasm was 5.9 ± 3.1 vs. 4.5 ± 2.1 Gy. Treatment time was 53.7 ± 5.8 (64.9 ± 24.3) minutes for GK and 4.8 ± 1.3 (5.0 ± 0.7) minutes for RA for schwannomas (meningiomas). SRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency.

Surgical Strategies in Childhood Craniopharyngioma

PubMed Central

Flitsch, Jörg; Müller, Hermann Lothar; Burkhardt, Till

2011-01-01

Craniopharyngiomas are biologically benign lesions (WHO Grade 1) of the sellar and suprasellar region, associated with a serious morbidity. About 50% of these tumors become clinically apparent during childhood. Clinical symptoms include headaches, chiasm syndrome, hydrocephalus, pituitary insufficiencies, and obesity. Growth arrest is a typical symptom in children. The treatment of craniopharyngiomas includes surgery as well as radiotherapy. The goal of surgery varies according to the tumor location and extension and may range from complete resection to biopsy. Surgical complications are well known and cause constant evaluation of surgical strategies. Diencephalic obesity is related to surgical manipulation of hypothalamic tissue. Therefore, a classification system for craniopharyngiomas based on preoperative MRI is suggested by the authors. Recurrences are frequent in craniopharyngiomas, even after complete or gross-total resection. Radiotherapy is therefore recommended to patients with incomplete resections. However, the ideal time for radiotherapy after surgery is under discussion. The treatment of craniopharyngiomas requires an interdisciplinary and multimodal approach. Each patient should receive an individually tailored treatment. Surgically, different approaches as well as different degrees of resection can be considered, depending on tumor location and tumor extension. PMID:22645514

Heuristic knowledge-based planning for single-isocenter stereotactic radiosurgery to multiple brain metastases.

PubMed

Ziemer, Benjamin P; Sanghvi, Parag; Hattangadi-Gluth, Jona; Moore, Kevin L

2017-10-01

Single-isocenter, volumetric-modulated arc therapy (VMAT) stereotactic radiosurgery (SRS) for multiple brain metastases (multimets) can deliver highly conformal dose distributions and reduce overall patient treatment time compared to other techniques. However, treatment planning for multimet cases is highly complex due to variability in numbers and sizes of brain metastases, as well as their relative proximity to organs-at-risk (OARs). The purpose of this study was to automate the VMAT planning of multimet cases through a knowledge-based planning (KBP) approach that adapts single-target SRS dose predictions to multiple target predictions. Using a previously published artificial neural network (ANN) KBP system trained on single-target, linac-based SRS plans, 3D dose distribution predictions for multimet patients were obtained by treating each brain lesion as a solitary target and subsequently combining individual dose predictions into a single distribution. Spatial dose distributions di(r→) for each of the i = 1…N lesions were merged using the combination function d(r→)=∑iNdin(r→)1/n. The optimal value of n was determined by minimizing root-mean squared (RMS) difference between clinical multimet plans and predicted dose per unit length along the line profile joining each lesion in the clinical cohort. The gradient measure GM=[3/4π]1/3V50%1/3-V100%1/3 is the primary quality metric for SRS plan evaluation at our institution and served as the main comparative metric between clinical plans and the KBP results. A total of 41 previously treated multimet plans, with target numbers ranging from N = 2-10, were used to validate the ANN predictions and subsequent KBP auto-planning routine. Fully deliverable KBP plans were developed by converting predicted dose distribution into patient-specific optimization objectives for the clinical treatment planning system (TPS). Plan parity was maintained through identical arc configuration and target normalization. Overall plan quality improvements were quantified by calculating the difference between SRS quality metrics (QMs): ΔQM = QM clinical  - QM KBP . In addition to GM, investigated QMs were: volume of brain receiving ≥ 10 Gy (V 10 Gy ), volume of brain receiving ≥ 5 Gy (ΔV 5 Gy ), heterogeneity index (HI), dose to 0.1 cc of the brainstem (D 0.1 cc ), dose to 1% of the optic chiasm (D 1% ), and interlesion dose (D IL ). In addition to this quantitative analysis, overall plan quality was assessed via blinded plan comparison of the manual and KBP treatment plans by SRS-specializing physicians. A dose combination factor of n = 8 yielded an integrated dose profile RMS difference of 2.9% across the 41-patient cohort. Multimet dose predictions exhibited ΔGM = 0.07 ± 0.10 cm against the clinical sample, implying either further normal tissue sparing was possible or that dose predictions were slightly overestimating achievable dose gradients. The latter is the more likely explanation, as this bias vanished when dose predictions were converted to deliverable KBP plans ΔGM = 0.00 ± 0.08 cm. Remaining QMs were nearly identical or showed modest improvements in the KBP sample. Equivalent QMs included: ΔV 10 Gy  = 0.37 ± 3.78 cc, ΔHI = 0.02 ± 0.08 and ΔD IL  = -2.22 ± 171.4 cGy. The KBP plans showed a greater degree of normal tissue sparing as indicated by brain ΔV 5 Gy  = 4.11± 24.05 cc, brainstem ΔD 0.1 cc  = 42.8 ± 121.4 cGy, and chiasm ΔD 1%  = 50.8 ± 83.0 cGy. In blinded review by SRS-specializing physicians, KBP-generated plans were deemed equivalent or superior in 32/41(78.1%) of the cases. Heuristic KBP-driven automated planning in linac-based, single-isocenter treatments for multiple brain metastases maintained or exceeded overall plan quality. © 2017 American Association of Physicists in Medicine.

Critical appraisal of RapidArc radiosurgery with flattening filter free photon beams for benign brain lesions in comparison to GammaKnife: a treatment planning study

PubMed Central

2014-01-01

Background To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique. Methods Twelve patients with vestibular schwannoma (VS, n = 6) or cavernous sinus meningioma (CSM, n = 6) were planned for both SRS using volumetric modulated arc therapy (VMAT) by RA. 104 MV flattening filter free photon beams with a maximum dose rate of 2400 MU/min were selected. Data were compared against plans optimised for GK. A single dose of 12.5 Gy was prescribed. The primary objective was to assess treatment plan quality. Secondary aim was to appraise treatment efficiency. Results For VS, comparing best GK vs. RA plans, homogeneity was 51.7 ± 3.5 vs. 6.4 ± 1.5%; Paddick conformity Index (PCI) resulted 0.81 ± 0.03 vs. 0.84 ± 0.04. Gradient index (PGI) was 2.7 ± 0.2 vs. 3.8 ± 0.6. Mean target dose was 17.1 ± 0.9 vs. 12.9 ± 0.1 Gy. For the brain stem, D1cm3 was 5.1 ± 2.0 Gy vs 4.8 ± 1.6 Gy. For the ipsilateral cochlea, D0.1cm3 was 1.7 ± 1.0 Gy vs. 1.8 ± 0.5 Gy. For CSM, homogeneity was 52.3 ± 2.4 vs. 12.4 ± 0.6; PCI: 0.86 ± 0.05 vs. 0.88 ± 0.05; PGI: 2.6 ± 0.1 vs. 3.8 ± 0.5; D1cm3 to brain stem was 5.4 ± 2.8 Gy vs. 5.2 ± 2.8 Gy; D0.1cm3 to ipsi-lateral optic nerve was 4.2 ± 2.1 vs. 2.1 ± 1.5 Gy; D0.1cm3 to optic chiasm was 5.9 ± 3.1 vs. 4.5 ± 2.1 Gy. Treatment time was 53.7 ± 5.8 (64.9 ± 24.3) minutes for GK and 4.8 ± 1.3 (5.0 ± 0.7) minutes for RA for schwannomas (meningiomas). Conclusions SRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency. PMID:24884967

[Structural CNS abnormalities responsible for coincidental occurrence of endocrine disorders, epilepsy and psychoneurologic disorders in children and adolescents].

PubMed

Starzyk, Jerzy; Kwiatkowski, Stanisław; Kaciński, Marek; Kroczka, Sławomir; Wójcik, Małgorzata

2010-01-01

In the population of children and adolescents, epilepsy affects 0.5-1% of individuals; approximately 3% of general population suffer from non-epileptic seizures, while endocrine disorders are several times more frequent. All of the above factors result in a relatively common non-accidental occurrence of endocrine disorders, epilepsy and neuropsychiatric disorders. However, structural central nervous system (CNS) abnormalities that cause both endocrine and neurologic disorders seem to be markedly less common. No reports addressing this problem are available in the literature. 1) Assessment of the frequency of non-coincidental occurrence of epilepsy and endocrine disorders in inpatients and outpatients with structural CSN abnormalities managed in Department Endocrinology. 2) Presentation of diagnostic and therapeutic difficulties in these patients, and 3) An attempt at defining a common etiology of both disorders. A retrospective analysis of the medical records of the patients with coincidence of endocrine disorders and epilepsy and psycho-neurologic disorders (treated in Chair and Department of Children's and Adolescents Neurology, University Children's Hospital of Krakow or in another pediatric neurology center) and with organic CNS abnormalities (treated or followed up as inpatients and outpatient of Department of Pediatric Surgery, Children's University Hospital of Krakow, was performed. The patients were selected from among several thousands of children treated as inpatients and outpatients of the Department. Various forms of symptomatic and idiopathic epilepsy and other psychoneurological disorders (disorders of behavior and emotions, obsession-compulsion syndromes, stereotypias, aggression, compulsive ideas and movements, anorexia or hypothalamic obesity) coincident with one or more endocrine disorders such as precocious or delayed puberty, multihormonal pituitary deficiency, panhypopituitarism and secondary hypothyroidism were detected in 42 patients with suprasellar arachnoid cyst (7 patients), septo-optic dysplasia (8 patients), craniopharyngioma (15 patients), glioma of the optic chiasm in neurofibromatosis type 1 (NF-1) (12 patients). There were no endocrine disorders in any of the ten patients with hamartoma of the hypothalamus and CPP. Endocrine and/ or neurological disorders did not resolve or were progressive after neurosurgery. Of 42 patients, a group of seven children representative for individual disorders was selected. In those patients, the etiology of both endocrine disorders, epilepsy and neuropsychiatric disorders was suspected to be common. 1. Various structural CNS abnormalities are the cause of concomitant epilepsy and endocrinopathy, although in some cases a direct impact of a genetic factor on the occurrence of both disorders or a mere coincidence cannot be ruled out. 2. Psychoneurological disorders usually precede the onset of endocrinopathy. 3. For this reason, MR or CT CNS imaging should be performed in any case of central neurological disorders, disorders of behavior, epilepsy, obsessive-compulsive syndrome, but also in patients with delayed psycho-motor development, delayed or accelerated growth and pubertal development. All of the above-mentioned manifestations may be symptoms of structural CNS abnormalities and their early treatment determines the child's future.

Assessment and quantification of patient set-up errors in nasopharyngeal cancer patients and their biological and dosimetric impact in terms of generalized equivalent uniform dose (gEUD), tumour control probability (TCP) and normal tissue complication probability (NTCP).

PubMed

Boughalia, A; Marcie, S; Fellah, M; Chami, S; Mekki, F

2015-06-01

The aim of this study is to assess and quantify patients' set-up errors using an electronic portal imaging device and to evaluate their dosimetric and biological impact in terms of generalized equivalent uniform dose (gEUD) on predictive models, such as the tumour control probability (TCP) and the normal tissue complication probability (NTCP). 20 patients treated for nasopharyngeal cancer were enrolled in the radiotherapy-oncology department of HCA. Systematic and random errors were quantified. The dosimetric and biological impact of these set-up errors on the target volume and the organ at risk (OARs) coverage were assessed using calculation of dose-volume histogram, gEUD, TCP and NTCP. For this purpose, an in-house software was developed and used. The standard deviations (1SDs) of the systematic set-up and random set-up errors were calculated for the lateral and subclavicular fields and gave the following results: ∑ = 0.63 ± (0.42) mm and σ = 3.75 ± (0.79) mm, respectively. Thus a planning organ at risk volume (PRV) margin of 3 mm was defined around the OARs, and a 5-mm margin used around the clinical target volume. The gEUD, TCP and NTCP calculations obtained with and without set-up errors have shown increased values for tumour, where ΔgEUD (tumour) = 1.94% Gy (p = 0.00721) and ΔTCP = 2.03%. The toxicity of OARs was quantified using gEUD and NTCP. The values of ΔgEUD (OARs) vary from 0.78% to 5.95% in the case of the brainstem and the optic chiasm, respectively. The corresponding ΔNTCP varies from 0.15% to 0.53%, respectively. The quantification of set-up errors has a dosimetric and biological impact on the tumour and on the OARs. The developed in-house software using the concept of gEUD, TCP and NTCP biological models has been successfully used in this study. It can be used also to optimize the treatment plan established for our patients. The gEUD, TCP and NTCP may be more suitable tools to assess the treatment plans before treating the patients.

Macro- and microadenoma of thyrotropin secreting pituitary tumors--two clinical cases.

PubMed

Hubalewska-Hola, Alicja; Fröss, Katarzyna; Kostecka-Matyja, Marta; Sowa-Staszczak, Anna; Szybiński, Zbigniew; Huszno, Bohdan; Ptak, Marzena

2003-01-01

Thyrotropin secreting adenoma, thyrotropinoma (TSH-oma), is a rare cause of hyperthyroidism--called secondary hyperthyroidism. The hormonal profile in pituitary hyperthyroidism is characterized by a nonsuppressed TSH in the presence of high levels of free thyroid hormones (fT4, fT3) reflecting an abnormal feedback. The diagnosis of TSH-oma is often made at the stage of macroadenoma because of the aggressive nature of the tumor and due to the fact that patients are mistakenly treated for more common primary hyperthyroidism for a long time. Two cases of TSH-secreting adenoma were detected in Chair and Department of Endocrinology, Collegium Medicum of the Jagiellonian University in Krakow for the last twenty years. Case 1: 49 year old woman was admitted to the Clinic of Endocrinology in 1999 with recurring hyperthyroidism treated with surgical thyroid ablation in 1992 and thyreostatics for the previous nine years. On admission to the Clinic her thyroid panel presented with elevated free hormone levels (mainly fT3-14.8 pmol/l) and not suppressed TSH-0.7 mIU/l suggesting central hyperthyroidism. MRI scan of the pituitary gland revealed microadenoma of 5 mm in diameter. She was qualified to transsphenoidal resection of the tumor. Histopathology revealed acidophilic adenoma with positive TSH staining. Thyroid hormones 8 days after the operation suggested full effectiveness of the surgery. Case 2: 65 year old man treated for one year with L-Thyroxin because of elevated TSH (60 mIU/l) and then with thyreostatics for elevated fT3 and fT4 was admitted to the Clinic of Endocrinology in 2000 with suspected thyrotropinoma. On admission to the Clinic thyroid panel suggested hyperthyroidism with fT4-40 pmol/l, FT3-11.2 pmol/l without suppression of TSH 2.2 mIU/l. MRI scan revealed a pituitary tumor 20 x 18 x 20 mm, compressing the optic chiasm. He was administered octreotide as a preparation for the operation. The patient underwent trans-sphenoidal resection of the adenoma (histopathologically a chromophobic adenoma). The example of presented patients suggests that clinical course of the pituitary tumor producing TSH and the rate of the tumor growth may differ significantly. Surgical resection of TSH producing adenoma is the most effective therapy. It should be proceeded by octreotide administration in patients with macroadenoma.

TU-EF-304-11: Therapeutic Benefits of Collimation in Spot Scanning Proton Therapy in the Treatment of Brain Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moignier, A; Gelover, E; Wang, D

Purpose: A dynamic collimation system (DCS) based on two orthogonal pairs of mobile trimmer blades has recently been proposed to reduce the lateral penumbra in spot scanning proton therapy (SSPT). The purpose of this work is to quantify the therapeutic benefit of using the DCS for SSPT of brain cancer by comparing un-collimated and collimated treatment plans. Methods: Un-collimated and collimated brain treatment plans were created for five patients, previously treated with SSPT, using an in-house treatment planning system capable of modeling collimated and un-collimated beamlets. Un-collimated plans reproduced the clinically delivered plans in terms of target coverage and organ-at-riskmore » (OAR) sparing, whereas collimated plans were re-optimized to improve the organ-at-risk sparing while maintaining target coverage. Physical and biological comparison metrics such as dose distribution conformity, mean and maximum doses, normal tissue complication probability (NTCP) and risk of secondary brain cancer were used to evaluate the plans. Results: The DCS systematically improved the dose distribution conformity while preserving the target coverage. The average reduction of the mean dose to the 10-mm ring surrounding the target and the healthy brain were 7.1% (95% CI: 4.2%–9.9%; p<0.01) and 14.3% (95% CI: 7.8%–20.8%; p<0.01), respectively. This yielded an average reduction of 12.0% (95% CI: 8.2%–15.7%; p<0.01) for the brain necrosis NTCP using the Flickinger model, and 14.2% (95% CI: 7.7%–20.8%; p<0.01) for the risk of secondary brain cancer. The average maximum dose reductions for the brainstem, chiasm, optic nerves, cochleae and pituitary gland when comparing un-collimated and collimated plans were 14.3%, 10.4%, 11.2%, 13.0%, 12.9% and 3.4%, respectively. Evaluating individual plans using the Lyman-Kutcher-Burman NTCP model also yielded improvements. Conclusion: The lateral penumbra reduction performed by the DCS increases the normal tissue sparing capabilities of SSPT for brain tumor treatment while preserving the target coverage. This research was financially supported by Ion Beam Applications S.A. (IBA, Louvain-La-Neuve, Belgium)« less

Assessment and quantification of patient set-up errors in nasopharyngeal cancer patients and their biological and dosimetric impact in terms of generalized equivalent uniform dose (gEUD), tumour control probability (TCP) and normal tissue complication probability (NTCP)

PubMed Central

Marcie, S; Fellah, M; Chami, S; Mekki, F

2015-01-01

Objective: The aim of this study is to assess and quantify patients' set-up errors using an electronic portal imaging device and to evaluate their dosimetric and biological impact in terms of generalized equivalent uniform dose (gEUD) on predictive models, such as the tumour control probability (TCP) and the normal tissue complication probability (NTCP). Methods: 20 patients treated for nasopharyngeal cancer were enrolled in the radiotherapy–oncology department of HCA. Systematic and random errors were quantified. The dosimetric and biological impact of these set-up errors on the target volume and the organ at risk (OARs) coverage were assessed using calculation of dose–volume histogram, gEUD, TCP and NTCP. For this purpose, an in-house software was developed and used. Results: The standard deviations (1SDs) of the systematic set-up and random set-up errors were calculated for the lateral and subclavicular fields and gave the following results: ∑ = 0.63 ± (0.42) mm and σ = 3.75 ± (0.79) mm, respectively. Thus a planning organ at risk volume (PRV) margin of 3 mm was defined around the OARs, and a 5-mm margin used around the clinical target volume. The gEUD, TCP and NTCP calculations obtained with and without set-up errors have shown increased values for tumour, where ΔgEUD (tumour) = 1.94% Gy (p = 0.00721) and ΔTCP = 2.03%. The toxicity of OARs was quantified using gEUD and NTCP. The values of ΔgEUD (OARs) vary from 0.78% to 5.95% in the case of the brainstem and the optic chiasm, respectively. The corresponding ΔNTCP varies from 0.15% to 0.53%, respectively. Conclusion: The quantification of set-up errors has a dosimetric and biological impact on the tumour and on the OARs. The developed in-house software using the concept of gEUD, TCP and NTCP biological models has been successfully used in this study. It can be used also to optimize the treatment plan established for our patients. Advances in knowledge: The gEUD, TCP and NTCP may be more suitable tools to assess the treatment plans before treating the patients. PMID:25882689

SU-F-303-12: Implementation of MR-Only Simulation for Brain Cancer: A Virtual Clinical Trial

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glide-Hurst, C; Zheng, W; Kim, J

2015-06-15

Purpose: To perform a retrospective virtual clinical trial using an MR-only workflow for a variety of brain cancer cases by incorporating novel imaging sequences, tissue segmentation using phase images, and an innovative synthetic CT (synCT) solution. Methods: Ten patients (16 lesions) were evaluated using a 1.0T MR-SIM including UTE-DIXON imaging (TE = 0.144/3.4/6.9ms). Bone-enhanced images were generated from DIXON-water/fat and inverted UTE. Automated air segmentation was performed using unwrapped UTE phase maps. Segmentation accuracy was assessed by calculating intersection and Dice similarity coefficients (DSC) using CT-SIM as ground truth. SynCTs were generated using voxel-based weighted summation incorporating T2, FLAIR, UTE1,more » and bone-enhanced images. Mean absolute error (MAE) characterized HU differences between synCT and CT-SIM. Dose was recalculated on synCTs; differences were quantified using planar gamma analysis (2%/2 mm dose difference/distance to agreement) at isocenter. Digitally reconstructed radiographs (DRRs) were compared. Results: On average, air maps intersected 80.8 ±5.5% (range: 71.8–88.8%) between MR-SIM and CT-SIM yielding DSCs of 0.78 ± 0.04 (range: 0.70–0.83). Whole-brain MAE between synCT and CT-SIM was 160.7±8.8 HU, with the largest uncertainty arising from bone (MAE = 423.3±33.2 HU). Gamma analysis revealed pass rates of 99.4 ± 0.04% between synCT and CT-SIM for the cohort. Dose volume histogram analysis revealed that synCT tended to yield slightly higher doses. Organs at risk such as the chiasm and optic nerves were most sensitive due to their proximities to air/bone interfaces. DRRs generated via synCT and CT-SIM were within clinical tolerances. Conclusion: Our approach for MR-only simulation for brain cancer treatment planning yielded clinically acceptable results relative to the CT-based benchmark. While slight dose differences were observed, reoptimization of treatment plans and improved image registration can address this limitation. Future work will incorporate automated registration between setup images (cone-beam CT and kilovoltage images) for synCT and CT-SIM. Submitting institution holds research agreements with Philips HealthCare, Best, Netherlands and Varian Medical Systems, Palo Alto, CA. Research partially sponsored via an Internal Mentored Research Grant.« less

Prospective randomized double-blind study of atlas-based organ-at-risk autosegmentation-assisted radiation planning in head and neck cancer.

PubMed

Walker, Gary V; Awan, Musaddiq; Tao, Randa; Koay, Eugene J; Boehling, Nicholas S; Grant, Jonathan D; Sittig, Dean F; Gunn, Gary Brandon; Garden, Adam S; Phan, Jack; Morrison, William H; Rosenthal, David I; Mohamed, Abdallah Sherif Radwan; Fuller, Clifton David

2014-09-01

Target volumes and organs-at-risk (OARs) for radiotherapy (RT) planning are manually defined, which is a tedious and inaccurate process. We sought to assess the feasibility, time reduction, and acceptability of an atlas-based autosegmentation (AS) compared to manual segmentation (MS) of OARs. A commercial platform generated 16 OARs. Resident physicians were randomly assigned to modify AS OAR (AS+R) or to draw MS OAR followed by attending physician correction. Dice similarity coefficient (DSC) was used to measure overlap between groups compared with attending approved OARs (DSC=1 means perfect overlap). 40 cases were segmented. Mean ± SD segmentation time in the AS+R group was 19.7 ± 8.0 min, compared to 28.5 ± 8.0 min in the MS cohort, amounting to a 30.9% time reduction (Wilcoxon p<0.01). For each OAR, AS DSC was statistically different from both AS+R and MS ROIs (all Steel-Dwass p<0.01) except the spinal cord and the mandible, suggesting oversight of AS/MS processes is required; AS+R and MS DSCs were non-different. AS compared to attending approved OAR DSCs varied considerably, with a chiasm mean ± SD DSC of 0.37 ± 0.32 and brainstem of 0.97 ± 0.03. Autosegmentation provides a time savings in head and neck regions of interest generation. However, attending physician approval remains vital. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Craniopharyngioma adherence: a comprehensive topographical categorization and outcome-related risk stratification model based on the methodical examination of 500 tumors.

PubMed

Prieto, Ruth; Pascual, José María; Rosdolsky, Maria; Castro-Dufourny, Inés; Carrasco, Rodrigo; Strauss, Sewan; Barrios, Laura

2016-12-01

OBJECTIVE Craniopharyngioma (CP) adherence strongly influences the potential for achieving a radical and safe surgical treatment. However, this factor remains poorly addressed in the scientific literature. This study provides a rational, comprehensive description of CP adherence that can be used for the prediction of surgical risks associated with the removal of these challenging lesions. METHODS This study retrospectively analyzes the evidence provided in pathological, neuroradiological, and surgical CP reports concerning 3 components of the CP attachment: 1) the intracranial structures attached to the tumor; 2) the morphology of the adhesion; and 3) the adhesion strength. From a total of 1781 CP reports published between 1857 and 2016, a collection of 500 CPs providing the best information about the type of CP attachment were investigated. This cohort includes autopsy studies (n = 254); surgical studies with a detailed description or pictorial evidence of CP adherence (n = 298); and surgical CP videos (n = 61) showing the technical steps for releasing the attachment. A predictive model of CP adherence in hierarchical severity levels correlated with surgical outcomes was generated by multivariate analysis. RESULTS The anatomical location of the CP attachment occurred predominantly at the third ventricle floor (TVF) (54%, n = 268), third ventricle walls (23%, n = 114), and pituitary stalk (19%, n = 94). The optic chiasm was involved in 56% (n = 281). Six morphological patterns of CP attachment were identified: 1) fibrovascular pedicle (5.4%); 2) sessile or patch-like (21%); 3) cap-like (over the CP top, 14%); 4) bowl-like (around the CP bottom, 13.5%); 5) ring-like (encircling central band, 19%); and 6) circumferential (enveloping the entire CP, 27%). Adhesion strength was classified in 4 grades: 1) loose (easily dissectible, 8%); 2) tight (requires sharp dissection, 32%); 3) fusion (no clear cleavage plane, 40%); and 4) replacement (loss of brain tissue integrity, 20%). The types of CP attachment associated with the worst surgical outcomes are the ring-like, bowl-like, and circumferential ones with fusion to the TVF or replacement of this structure (p < 0.001). The CP topography is the variable that best predicts the type of CP attachment (p < 0.001). Ring-like and circumferential attachments were observed for CPs invading the TVF (secondary intraventricular CPs) and CPs developing within the TVF itself (infundibulo-tuberal CPs). Brain invasion and peritumoral gliosis occurred predominantly in the ring-like and circumferential adherence patterns (p < 0.001). A multivariate model including the variables CP topography, tumor consistency, and the presence of hydrocephalus, infundibulo-tuberal syndrome, and/or hypothalamic dysfunction accurately predicts the severity of CP attachment in 87% of cases. CONCLUSIONS A comprehensive descriptive model of CP adherence in 5 hierarchical levels of increased severity-mild, moderate, serious, severe, and critical-was generated. This model, based on the location, morphology, and strength of the attachment can be used to anticipate the surgical risk of hypothalamic injury and to plan the degree of removal accordingly.

Fever produced by endotoxin injected into the hypothalamus of the monkey and its antagonism by salicylate

PubMed Central

Myers, R. D.; Rudy, T. A.; Yaksh, T. L.

1974-01-01

1. A suspension of the killed cell bodies of either E. coli, S. dysenteriae or S. typhosa was micro-injected through cannulae implanted chronically at specific sites within the diencephalon and mid-brain of the unanaesthetized monkey. A biphasic, monophasic or an undifferentiated fever could be induced by each type of micro-organism, but the type of response depended solely upon the locus of injection. 2. Although little difference in the potency of the three pyrogens was found, the rise in body temperature was in each instance dependent upon the concentration of the endotoxin. A more intense fever was accompanied by shivering, vasoconstriction of the ear vessels, piloerection and huddling behaviour. Tolerance to the pyrexic effect of repeated injections of endotoxin did not develop. 3. The febrile response having the shortest latency, greatest maximum rise in temperature and largest 10-hr fever index was evoked by micro-injections into the anterior hypothalamic, preoptic area. The incidence of biphasic fevers was also greater after endotoxin was injected into this same region. Endotoxin given similarly in the posterior hypothalamus or in the mesencephalon had either no effect or produced a smaller elevation in temperature after a longer latency. The distance of an injection site from the coronal plane formed by the optic chiasm and anterior commissure correlated significantly with the latency and magnitude of the temperature change as well as the fever index. 4. When given intravenously, endotoxin in a quantity at least 100 times greater was required to evoke a fever similar to that produced when the pyrogen was micro-injected into the anterior hypothalamic, preoptic region. However, a biphasic fever was evoked with a latency of from 3 to 15 min when a larger amount of endotoxin was injected intravenously. Tolerance developed rapidly to the febrile effect of endotoxin administered by this route although toxic reactions were not observed. 5. After the fever evoked by the hypothalamic injection of endotoxin had reached a plateau, 300-1200 mg sodium salicylate administered intragastrically produced a dose-dependent fall in temperature, but had no effect on the body temperature of an afebrile monkey. 6. It is concluded that in the rhesus monkey, a bacterial pyrogen can evoke a fever which is mediated entirely by an action on the central nervous system, the principal site being the anterior hypothalamic, preoptic area. The first phase of a biphasic fever caused by bacteria acting either by the central or peripheral route seems to be due either to a direct action of the pyrogen on the cells of the anterior hypothalamus, or to the secondary release within this region of an intermediary thermogenic substance such as 5-hydroxytryptamine or prostaglandin. The finding that sodium salicylate counteracts a centrally evoked fever is not compatible with the hypothesis that an antipyretic exerts its action by preventing a pyrogen that is circulating in the blood stream from entering the central nervous system. PMID:4615138

Practical aspects and applications of the biological effective dose three-dimensional calculation for multi-phase radiotherapy treatment plans

NASA Astrophysics Data System (ADS)

Kauweloa, Kevin Ikaika

The approximate BED (BEDA) is calculated for multi-phase cases due to current treatment planning systems (TPSs) being incapable of performing BED calculations. There has been no study on the mathematical accuracy and precision of BEDA relative to the true BED (BEDT), and how that might negatively impact patient care. The purpose of the first aim was to study the mathematical accuracy and precision in both hypothetical and clinical situations, while the next two aims were to create multi-phase BED optimization ideas for both multi-target liver stereotactic body radiation therapy (SBRT) cases, and gynecological cases where patients are treated with high-dose rate (HDR) brachytherapy along with external beam radiotherapy (EBRT). MATLAB algorithms created for this work were used to mathematically analyze the accuracy and precision of BEDA relative to BEDT in both hypothetical and clinical situations on a 3D basis. The organs-at-risk (OARs) of ten head & neck and ten prostate cancer patients were studied for the clinical situations. The accuracy of BEDA was shown to vary between OARs as well as between patients. The percentage of patients with an overall BEDA percent error less than 1% were, 50% for the Optic Chiasm and Brainstem, 70% for the Left and Right Optic Nerves, as well as the Rectum and Bladder, and 80% for the Normal Brain and Spinal Cord. As seen for each OAR among different patients, there were always cases where the percent error was greater than 1%. This is a cause for concern since the goal of radiation therapy is to reduce the overall uncertainty of treatment, and calculating BEDA distributions increases the treatment uncertainty with percent errors greater than 1%. The revealed inaccuracy and imprecision of BEDA supports the argument to use BEDT. The multi-target liver study involved applying BEDT in order to reduce the number of dose limits to one rather than have one for each fractionation scheme in multi-target liver SBRT treatments. A BEDT limit was found using the current, clinically accepted dose limits, allowing the BEDT distributions to be calculated, which could be used to determine whether at least 700 cc of the healthy liver did not receive the BEDT limit. Three previously multi-target liver cancer patients were studied. For each case, it was shown that the conventional treatment plans were relatively conservative and that more than 700 cc of the healthy liver received less than the BED T limit. These results show that greater doses can be delivered to the targets without exceeding the BEDT limit to the healthy tissue, which typically causes radiation toxicity. When applying BEDT to gynecological cases, the BEDT can reveal the relative effect each treatment would have individually hence the cumulative BEDT would better inform the physician of the potential results with the patient's treatment. The problem presented for these cases, however, is the method in summing dose distributions together when there is significant motion between treatments and the presence of applicators for the HDR phase. One way to calculate the cumulative BEDT is to use structure guided deformable image registration (SG-DIR) that only focuses on the anatomical contours, to avoid errors introduced by the applicators. Eighteen gynecological patients were studied and VelocityAI was used to perform this SG- DIR. In addition, formalism was developed to assess and characterize the remnant dose-mapping error from this approach, from the shortest distance between contour points (SDBP). The results revealed that warping errors rendered relatively large normal tissue complication probability (NTCP) values which are certainly non negligible and does render this method not clinically viable. However, a more accurate SG-DIR algorithm could improve the accuracy of BEDT distributions in these multi-phase cases.

Topographic Diagnosis of Craniopharyngiomas: The Accuracy of MRI Findings Observed on Conventional T1 and T2 Images.

PubMed

Prieto, R; Pascual, J M; Barrios, L

2017-11-01

The topography of craniopharyngiomas has proved fundamental in predicting the involvement of vital brain structures and the possibility of achieving a safe radical resection. Beyond the imprecise term "suprasellar," indiscriminately used for craniopharyngiomas, an accurate definition of craniopharyngioma topography should be assessed by preoperative MR imaging. The objective of this study was to investigate the MRI findings that help define craniopharyngioma topography. This study retrospectively investigated a cohort of 200 surgically treated craniopharyngiomas with their corresponding preoperative midsagittal and coronal conventional T1- and T2-weighted MR images, along with detailed descriptions of the surgical findings. Radiologic variables related to the occupation of the tumor of intracranial compartments and the distortions of anatomic structures along the sella turcica-third ventricle axis were analyzed and correlated with the definitive craniopharyngioma topography observed during the surgical procedures. A predictive model for craniopharyngioma topography was generated by multivariate analysis. Five major craniopharyngioma topographies can be defined according to the degree of hypothalamic distortion caused by the tumor: sellar-suprasellar, pseudointraventricular, secondary intraventricular, not strictly intraventricular, and strictly intraventricular. Seven key radiologic variables identified on preoperative MRI allowed a correct overall prediction of craniopharyngioma topography in 86% of cases: 1) third ventricle occupation, 2) pituitary stalk distortion, 3) relative level of the hypothalamus in relation to the tumor, 4) chiasmatic cistern occupation, 5) mammillary body angle, 6) type of chiasm distortion, and 7) tumor shape. Systematic assessment of these 7 variables on conventional preoperative T1 and T2 MRI is a useful and reliable method to ascertain individual craniopharyngioma topography. © 2017 by American Journal of Neuroradiology.

Delayed Diagnosis of Acromegaly in the Context of Post-Traumatic Stress Disorder due to Symptoms Mimicking Known Psychotropic Medication Side Effects.

PubMed

Portier, Ray-Bernard; Afarin, Afshin; Pope, Sara

2017-07-01

Acromegaly is caused by elevated secretion of human growth hormone, which is frequently because of intracranial tumors. This diagnosis is fairly uncommon with an incidence of 3 to 4 cases per million patients per year. We are presenting a case of acromegaly diagnosed in an active duty Chief Petty Officer. A 38-year-old male Chief Petty Officer with no previous mental health diagnosis experienced post-traumatic stress disorder (PTSD)-like symptoms in early 2012 after deploying to Iraq and Afghanistan from 2010 to 2011. Initially he self-managed his symptoms, but in July 2012 he required a reduction mammoplasty because of gynecomastia. The metabolic workup revealed elevated prolactin, but this was not further investigated. His recovery from anesthesia was complicated by intensified PTSD-like symptoms, which continued to worsen after the surgery. On self-referral to mental health, he was diagnosed with PTSD and managed for 6 months with cognitive behavioral therapy. Because of persistent and worsening symptoms, his therapy was augmented to include continued cognitive behavioral therapy, alpha-blockers, antidepressants, antihistamines, and sleep aids. Because of night sweats, the selective serotonin reuptake inhibitors doses were modified. Night sweats persisted, and the patient was re-evaluated for other potential etiologies. On evaluation, the patient endorsed a history of obstructive sleep apnea, cervicalgia, visual changes, depressed mood, as well as multiple physical symptoms including coarsened facial features, large hands/feet, and increased interdental distance. On laboratory analysis, insulin-like growth factor 1 was noted to be 3 times the upper limit of normal, and a prolactin level was five times the upper limit of normal. A brain magnetic resonance imaging revealed a cystic pituitary lesion with suprasellar extension, compression of the infundibulum without invasion of the cavernous sinus, or displacement of the optic chiasm. Based on clinical history, physical examination, laboratory data, and the pituitary lesion, this patient was diagnosed with acromegaly. He was referred to neurosurgery for further evaluation and management. This case shows that side effects of medications can easily mimic some medical conditions. The possibility of unrecognized disease should not be overlooked simply because a patient's symptoms that develop after starting a medication correspond well the side effect profile of the prescribed medications. This is especially true if side effects do not stop with alteration of medication dose, cessation of the medication, or changing to another medication. Pituitary adenomas are rare in patients treated for PTSD. However, attribution of PTSD patient's symptoms to the side effects of selective serotonin reuptake inhibitors therapy without considering a broader differential may lead to a missed diagnosis of an endocrine disease. In this case, the presence of an undiagnosed pituitary lesion resulted in ineffective medical management of PTSD in the patient. Mental health providers should remain allied with their primary care counterparts and consider directing patients to primary care for periodic physical re-evaluation to provide the most effective approach to symptom evaluation and management. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

[Non-structural abnormalities of CNS function resulting in coincidence of endocrinopathies, epilepsy and psychoneurologic disorders in children and adolescents].

PubMed

Starzyk, Jerzy; Pituch-Noworolska, Anna; Pietrzyk, Jacek A; Urbanik, Andrzej; Kroczka, Sławomir; Drozdz, Ryszard; Wójcik, Małgorzata

2010-01-01

In the population of children and adolescents, epilepsy affects approximately 1% of cases, nonepileptic seizures are seen in approximately 3%, and endocrine disorders are several times more common. For this reason, coincidence of endocrine disorders and epilepsy and psychoneurologic disorders is frequent. Much less common are structural abnormalities (tumors, developmental abnormalities), and especially non-structural CNS abnormalities, resulting in coincidence of both disorders. There are no reports available in the literature that would address the problem. 1) Assessment of the frequency of coincidental epilepsy and endocrine disorders in patients without structural CSN abnormalities treated as outpatients and inpatients of Department of Endocrinology University Children's Hospital of Krakow. 2) Presentation of diagnostic and therapeutic difficulties in these patients, and 3) An attempt at defining the common etiology of both disorders. On the basis of ICD code patients with coincidance of endocrine disorders, epilepsy and psychoneurologic disorders were selected from several thousands of children treated between 2000 and 2009 in Pediatric Endocrinology Department. The neurologic disorders were diagnosed and treated in Chair and Department of Children's and Adolescents Neurology or in another pediatric neurology center. Various forms of epilepsy (symptomatic or idiopathic) and other psychoneurological disorders (disorders of behavior and emotions, obsession-compulsion syndromes, stereotypias, aggression, autoaggression, or hypothalamic obesity) coincident with one or more endocrine disorders, such as growth disorders, disorders of pubertal development, obesity, thyroid diseases, adrenal diseases, hyperprolactinemia, hypoparathyroidism and ion metabolism disorders were diagnosed in 49 patients. The group included: i) children after cranial irradiation and chemotherapy due to medulloblastoma (3 patients), oligodenroglioma (1 patient), ependymoma (1 patient), optic chiasm glioma (2 patients), suprasellar germinal tumor (1 patient), ii) children with Hashimoto encephalopathy (2 patients), iii) children with Prader-Willi syndrome (20 patients), with Klinefelter syndrome (10 patients), with Albright syndrome (9 patients). Of the 49 patients, a group of 6 children representative for individual disorders was selected. In those patients, the etiology of both endocrine disorders, epilepsy and neuropsychiatric disorders was suspected to be common, and the diagnosis was usually delayed. 1. Cranial irradiation and chemotherapy, encephalopathy associated with Hashimoto disease and some of the syndromes with the chromosomal and genetic background are the causes of non-structural CNS abnormalities and coincidence of endocrinopathies, epilepsy and psychoneurologic disorders. 2. MR/CT CNS imaging should be performed in any case of central neurological disorders, disorders of behavior, epilepsy or seizures, but also in patients with delayed psycho-motor development, delayed or accelerated growth and pubertal development. All of the above-mentioned manifestations may be symptoms of structural CNS abnormalities and their early treatment determines the child's future. 3. Excluding structural CNS abnormalities allows for forming suspicions associated with diseases resulting in non-structural disorders of the CNS function, predisposing to coincidence of endocrine and neurological disorders. 4. In the diagnosis of Hashimoto's encephalopathy, a decisive factor is exclusion of structural, infectious, traumatic and metabolic causes, intoxications, epilepsy and presence of neuropsychiatric symptoms in patients with high level of against TPO antibodies. In cases of steroids resistance, a good therapeutic effect may be achieved by plasmapheresis, Rituximab therapy and progestagene inhibition of the menstrual cycle.

WE-AB-209-09: Optimization of Rotational Arc Station Parameter Optimized Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, P; Xing, L; Ungun, B

Purpose: To develop a fast optimization method for station parameter optimized radiation therapy (SPORT) and show that SPORT is capable of improving VMAT in both plan quality and delivery efficiency. Methods: The angular space from 0° to 360° was divided into 180 station points (SPs). A candidate aperture was assigned to each of the SPs based on the calculation results using a column generation algorithm. The weights of the apertures were then obtained by optimizing the objective function using a state-of-the-art GPU based Proximal Operator Graph Solver (POGS) within seconds. Apertures with zero or low weight were thrown out. Tomore » avoid being trapped in a local minimum, a stochastic gradient descent method was employed which also greatly increased the convergence rate of the objective function. The above procedure repeated until the plan could not be improved any further. A weighting factor associated with the total plan MU also indirectly controlled the complexities of aperture shapes. The number of apertures for VMAT and SPORT was confined to 180. The SPORT allowed the coexistence of multiple apertures in a single SP. The optimization technique was assessed by using three clinical cases (prostate, H&N and brain). Results: Marked dosimetric quality improvement was demonstrated in the SPORT plans for all three studied cases. Prostate case: the volume of the 50% prescription dose was decreased by 22% for the rectum. H&N case: SPORT improved the mean dose for the left and right parotids by 15% each. Brain case: the doses to the eyes, chiasm and inner ears were all improved. SPORT shortened the treatment time by ∼1 min for the prostate case, ∼0.5 min for brain case, and ∼0.2 min for the H&N case. Conclusion: The superior dosimetric quality and delivery efficiency presented here indicates that SPORT is an intriguing alternative treatment modality.« less

Modules and methods for all photonic computing

DOEpatents

Schultz, David R.; Ma, Chao Hung

2001-01-01

A method for all photonic computing, comprising the steps of: encoding a first optical/electro-optical element with a two dimensional mathematical function representing input data; illuminating the first optical/electro-optical element with a collimated beam of light; illuminating a second optical/electro-optical element with light from the first optical/electro-optical element, the second optical/electro-optical element having a characteristic response corresponding to an iterative algorithm useful for solving a partial differential equation; iteratively recirculating the signal through the second optical/electro-optical element with light from the second optical/electro-optical element for a predetermined number of iterations; and, after the predetermined number of iterations, optically and/or electro-optically collecting output data representing an iterative optical solution from the second optical/electro-optical element.

Soft optics in intelligent optical networks

NASA Astrophysics Data System (ADS)

Shue, Chikong; Cao, Yang

2001-10-01

In addition to the recent advances in Hard-optics that pushes the optical transmission speed, distance, wave density and optical switching capacity, Soft-optics provides the necessary intelligence and control software that reduces operational costs, increase efficiency, and enhances revenue generating services by automating optimal optical circuit placement and restoration, and enabling value-added new services like Optical VPN. This paper describes the advances in 1) Overall Hard-optics and Soft-optics 2) Layered hierarchy of Soft-optics 3) Component of Soft-optics, including hard-optics drivers, Management Soft-optics, Routing Soft-optics and System Soft-optics 4) Key component of Routing and System Soft-optics, namely optical routing and signaling (including UNI/NNI and GMPLS signaling). In summary, the soft-optics on a new generation of OXC's enables Intelligent Optical Networks to provide just-in-time service delivery and fast restoration, and real-time capacity management that eliminates stranded bandwidth. It reduces operational costs and provides new revenue opportunities.

Chip-to-chip optical link by using optical wiring method

NASA Astrophysics Data System (ADS)

Cho, In-Kui; Ahn, Seoung Ho; Jeong, Myung-Yung; Rho, Byung Sup; Park, Hyo Hoon

2008-01-01

A practical optical link system was prepared with a transmitter (Tx) and receiver (Rx). The optical TRx module consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a VCSEL/PD array, and an optical link block composed of plastic optical fiber (POF). For the optical interconnection between the light-sources and detectors, an optical wiring method has been proposed to enable easy assembly. This paper provides a method for optical interconnection between an optical Tx and an optical Rx, comprising the following steps: (a) forming a light source device, an optical detection device, and an optical transmission unit on a substrate (metal optical bench (MOB)); (b) preparing a flexible optical transmission-connection medium (optical wiring link) to optically connect the light source device formed on the substrate with the optical detection device; and (c) directly connecting one end of the surface-finished optical transmission connection medium with the light source device and the other end with the optical detection device. A chip-to-chip optical link system constructed with TRx modules was fabricated and the optical characteristics were measured. The results clearly demonstrate that the use of an optical wiring method can provide robust and cost-effective assembly for vertical-cavity surface-emitting lasers (VCSELs) and photodiodes (PDs). We successfully achieved a 5 Gb/s data transmission rate with this optical link.

Optical link by using optical wiring method for reducing EMI

NASA Astrophysics Data System (ADS)

Cho, In-Kui; Kwon, Jong-Hwa; Choi, Sung-Woong; Bondarik, Alexander; Yun, Je-Hoon; Kim, Chang-Joo; Ahn, Seung-Beom; Jeong, Myung-Yung; Park, Hyo Hoon

2008-12-01

A practical optical link system was prepared with a transmitter (Tx) and receiver (Rx) for reducing EMI (electromagnetic interference). The optical TRx module consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a VCSEL/PD array, and an optical link block composed of plastic optical fiber (POF). For the optical interconnection between the light-sources and detectors, an optical wiring method has been proposed to enable easy assembly. The key benefit of fiber optic link is the absence of electromagnetic interference (EMI) noise creation and susceptibility. This paper provides a method for optical interconnection between an optical Tx and an optical Rx, comprising the following steps: (i) forming a light source device, an optical detection device, and an optical transmission unit on a substrate (metal optical bench (MOB)); (ii) preparing a flexible optical transmission-connection medium (optical wiring link) to optically connect the light source device formed on the substrate with the optical detection device; and (iii) directly connecting one end of the surface-finished optical transmission connection medium with the light source device and the other end with the optical detection device. Electronic interconnections have uniquely electronic problems such as EMI, shorting, and ground loops. Since these problems only arise during transduction (electronics-to-optics or opticsto- electronics), the purely optical part and optical link(interconnection) is free of these problems. 1 An optical link system constructed with TRx modules was fabricated and the optical characteristics about data links and EMI levels were measured. The results clearly demonstrate that the use of an optical wiring method can provide robust and cost-effective assembly for reducing EMI of inter-chip interconnect. We successfully achieved a 4.5 Gb/s data transmission rate without EMI problems.

Optical integrator for optical dark-soliton detection and pulse shaping.

PubMed

Ngo, Nam Quoc

2006-09-10

The design and analysis of an Nth-order optical integrator using the digital filter technique is presented. The optical integrator is synthesized using planar-waveguide technology. It is shown that a first-order optical integrator can be used as an optical dark-soliton detector by converting an optical dark-soliton pulse into an optical bell-shaped pulse for ease of detection. The optical integrators can generate an optical step function, staircase function, and paraboliclike functions from input optical Gaussian pulses. The optical integrators may be potentially used as basic building blocks of all-optical signal processing systems because the time integrals of signals may sometimes be required for further use or analysis. Furthermore, an optical integrator may be used for the shaping of optical pulses or in an optical feedback control system.

Controlling lightwave in Riemann space by merging geometrical optics with transformation optics.

PubMed

Liu, Yichao; Sun, Fei; He, Sailing

2018-01-11

In geometrical optical design, we only need to choose a suitable combination of lenses, prims, and mirrors to design an optical path. It is a simple and classic method for engineers. However, people cannot design fantastical optical devices such as invisibility cloaks, optical wormholes, etc. by geometrical optics. Transformation optics has paved the way for these complicated designs. However, controlling the propagation of light by transformation optics is not a direct design process like geometrical optics. In this study, a novel mixed method for optical design is proposed which has both the simplicity of classic geometrical optics and the flexibility of transformation optics. This mixed method overcomes the limitations of classic optical design; at the same time, it gives intuitive guidance for optical design by transformation optics. Three novel optical devices with fantastic functions have been designed using this mixed method, including asymmetrical transmissions, bidirectional focusing, and bidirectional cloaking. These optical devices cannot be implemented by classic optics alone and are also too complicated to be designed by pure transformation optics. Numerical simulations based on both the ray tracing method and full-wave simulation method are carried out to verify the performance of these three optical devices.

Laser interlock system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodruff, Steven D; Mcintyre, Dustin L

2015-01-13

A method and device for providing a laser interlock having a first optical source, a first beam splitter, a second optical source, a detector, an interlock control system, and a means for producing dangerous optical energy. The first beam splitter is optically connected to the first optical source, the first detector and the second optical source. The detector is connected to the interlock control system. The interlock control system is connected to the means for producing dangerous optical energy and configured to terminate its optical energy production upon the detection of optical energy at the detector from the second opticalmore » source below a predetermined detector threshold. The second optical source produces an optical energy in response to optical energy from the first optical source. The optical energy from the second optical source has a different wavelength, polarization, modulation or combination thereof from the optical energy of the first optical source.« less

Nonlinear Optical Acrylic Polymers and Use Thereof in Optical and Electro-Optic Devices

DTIC Science & Technology

1992-01-07

COVERED 4. TITLE AND SUBTITLE Nonlinear Optical Acrylic Polymers and Use Thereof in Optical and Electro - Optic Devices 5a. CONTRACT NUMBER 5b. GRANT...generators, computational devices and the like. 15. SUBJECT TERMS optical devices, electro - optical devices, optical signal processing...THEREOF IN OPTICAL AND ELECTRO - OPTIC DEVICES [75] Inventors: Le*lie H. Sperling, Bethlehem; Clarence J. Murphy, Stroudsburg; Warren A. Rosen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tauke-Pedretti, Anna; Skogen, Erik J; Vawter, Gregory A

An optical sampler includes a first and second 1.times.n optical beam splitters splitting an input optical sampling signal and an optical analog input signal into n parallel channels, respectively, a plurality of optical delay elements providing n parallel delayed input optical sampling signals, n photodiodes converting the n parallel optical analog input signals into n respective electrical output signals, and n optical modulators modulating the input optical sampling signal or the optical analog input signal by the respective electrical output signals, and providing n successive optical samples of the optical analog input signal. A plurality of output photodiodes and eADCsmore » convert the n successive optical samples to n successive digital samples. The optical modulator may be a photodiode interconnected Mach-Zehnder Modulator. A method of sampling the optical analog input signal is disclosed.« less

A novel all-optical label processing based on multiple optical orthogonal codes sequences for optical packet switching networks

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun; Xu, Bo; Ling, Yun

2008-05-01

This paper proposes an all-optical label processing scheme that uses the multiple optical orthogonal codes sequences (MOOCS)-based optical label for optical packet switching (OPS) (MOOCS-OPS) networks. In this scheme, each MOOCS is a permutation or combination of the multiple optical orthogonal codes (MOOC) selected from the multiple-groups optical orthogonal codes (MGOOC). Following a comparison of different optical label processing (OLP) schemes, the principles of MOOCS-OPS network are given and analyzed. Firstly, theoretical analyses are used to prove that MOOCS is able to greatly enlarge the number of available optical labels when compared to the previous single optical orthogonal code (SOOC) for OPS (SOOC-OPS) network. Then, the key units of the MOOCS-based optical label packets, including optical packet generation, optical label erasing, optical label extraction and optical label rewriting etc., are given and studied. These results are used to verify that the proposed MOOCS-OPS scheme is feasible.

Recent Advances in Photonic Devices for Optical Computing and the Role of Nonlinear Optics-Part II

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin; Frazier, Donald O.; Witherow, William K.; Banks, Curtis E.; Paley, Mark S.

2007-01-01

The twentieth century has been the era of semiconductor materials and electronic technology while this millennium is expected to be the age of photonic materials and all-optical technology. Optical technology has led to countless optical devices that have become indispensable in our daily lives in storage area networks, parallel processing, optical switches, all-optical data networks, holographic storage devices, and biometric devices at airports. This chapters intends to bring some awareness to the state-of-the-art of optical technologies, which have potential for optical computing and demonstrate the role of nonlinear optics in many of these components. Our intent, in this Chapter, is to present an overview of the current status of optical computing, and a brief evaluation of the recent advances and performance of the following key components necessary to build an optical computing system: all-optical logic gates, adders, optical processors, optical storage, holographic storage, optical interconnects, spatial light modulators and optical materials.

State-of-the-art of optics in China reviewed

NASA Astrophysics Data System (ADS)

Wang, Daheng; Wo, Xinneng

1985-06-01

The state-of-the-art of optics and applied optics in China is reviewed. Developments in lasers, infrared and opto-electronic techniques, optical metrology, high-speed photography, holography and information processing, nonlinear optics, optical fiber communications and optical techniques are described. Further development of optics and applied optics in China are proposed.

Experimental demonstration of tunable multiple optical orthogonal codes sequences-based optical label for optical packets switching

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun; Zhou, Heng; Ling, Yun; Wang, Yawei; Xu, Bo

2010-03-01

In this paper, the tunable multiple optical orthogonal codes sequences (MOOCS)-based optical label for optical packet switching (OPS) (MOOCS-OPS) is experimentally demonstrated for the first time. The tunable MOOCS-based optical label is performed by using fiber Bragg grating (FBG)-based optical en/decoders group and optical switches configured by using Field Programmable Gate Array (FPGA), and the optical label is erased by using Semiconductor Optical Amplifier (SOA). Some waveforms of the MOOCS-based optical label, optical packet including the MOOCS-based optical label and the payloads are obtained, the switching control mechanism and the switching matrix are discussed, the bit error rate (BER) performance of this system is also studied. These experimental results show that the tunable MOOCS-OPS scheme is effective.

Universal method for constructing N-port non-blocking optical router based on 2 × 2 optical switch for photonic networks-on-chip.

PubMed

Chen, Qiaoshan; Zhang, Fanfan; Ji, Ruiqiang; Zhang, Lei; Yang, Lin

2014-05-19

We propose a universal method for constructing N-port non-blocking optical router for photonic networks-on-chip, in which all microring (MR) optical switches or Mach-Zehnder (M-Z) optical switches behave as 2 × 2 optical switches. The optical router constructed by the proposed method has minimum optical switches, in which the number of the optical switches is reduced about 50% compared to the reported optical routers based on MR optical switches and more than 30% compared to the reported optical routers based on M-Z optical switches, and therefore is more compact in footprint and more power-efficient. We also present a strict mathematical proof of the non-blocking routing of the proposed N-port optical router.

International Conference on Integrated Optical Circuit Engineering, 1st, Cambridge, MA, October 23-25, 1984, Proceedings

NASA Astrophysics Data System (ADS)

Ostrowsky, D. B.; Sriram, S.

Aspects of waveguide technology are explored, taking into account waveguide fabrication techniques in GaAs/GaAlAs, the design and fabrication of AlGaAs/GaAs phase couplers for optical integrated circuit applications, ion implanted GaAs integrated optics fabrication technology, a direct writing electron beam lithography based process for the realization of optoelectronic integrated circuits, and advances in the development of semiconductor integrated optical circuits for telecommunications. Other subjects examined are related to optical signal processing, optical switching, and questions of optical bistability and logic. Attention is given to acousto-optic techniques in integrated optics, acousto-optic Bragg diffraction in proton exchanged waveguides, optical threshold logic architectures for hybrid binary/residue processors, integrated optical modulation and switching, all-optic logic devices for waveguide optics, optoelectronic switching, high-speed photodetector switching, and a mechanical optical switch.

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

NASA Technical Reports Server (NTRS)

Depaula, Ramon P. (Editor); Udd, Eric (Editor)

1991-01-01

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Electro-optic and acousto-optic scanning and deflection

NASA Astrophysics Data System (ADS)

Gottlieb, M.; Ireland, C. L. M.; Ley, J. M.

This book attempts to cover sufficient electro- and acousto-optic theory for the reader to understand and appreciate the design and application of solid state optical deflectors. It is also hoped that for the more experienced engineer the book will serve as a useful reference book covering the most important work in this field of engineering. The theory of the electro-optic effect is considered along with the properties and selection of electro-optic materials, the principles of electro-optic deflectors, electro-optic deflector designs, and applications for electro-optic deflectors. Attention is given to EM wave propagation in a crystal, the linear electro-optic effect, the quadratic electro-optic effect in crystals and in liquids, electro-optic ceramics in the (Pb,La)(Zr,Ti)O3 system, and digital and analog light deflectors. Aspects related to acousto-optic deflectors are discussed, taking into account acousto-optic interactions, materials for acousto-optic scanning, acoustic techniques, scanning systems, and acousto-optic light diffraction in thin films.

Temporal laser pulse manipulation using multiple optical ring-cavities

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

2010-01-01

An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

Performance Evaluation of Titanium Ion Optics for the NASA 30 cm Ion Thruster

NASA Technical Reports Server (NTRS)

Soulas, George C.

2001-01-01

The results of performance tests with titanium ion optics were presented and compared to those of molybdenum ion optics. Both titanium and molybdenum ion optics were initially operated until ion optics performance parameters achieved steady state values. Afterwards, performance characterizations were conducted. This permitted proper performance comparisons of titanium and molybdenum ion optics. Ion optics' performance A,as characterized over a broad thruster input power range of 0.5 to 3.0 kW. All performance parameters for titanium ion optics of achieved steady state values after processing 1200 gm of propellant. Molybdenum ion optics exhibited no burn-in. Impingement-limited total voltages for titanium ion optics where up to 55 V greater than those for molybdenum ion optics. Comparisons of electron backstreaming limits as a function of peak beam current density for molybdenum and titanium ion optics demonstrated that titanium ion optics operated with a higher electron backstreaming limit than molybdenum ion optics for a given peak beam current density. Screen grid ion transparencies for titanium ion optics were as much as 3.8 percent lower than those for molybdenum ion optics. Beam divergence half-angles that enclosed 95 percent of the total beam current for titanium ion optics were within 1 to 3 deg. of those for molybdenum ion optics. All beam divergence thrust correction factors for titanium ion optics were within 1 percent of those with molybdenum ion optics.

Nonlinear and non-Hermitian optical systems applied to the development of filters and optical sensors

NASA Astrophysics Data System (ADS)

Amaro de Faria Júnior, A. C.

2015-09-01

In this work we present a method of investigation of nonlinear optical beams generated from non-Hermitian optical systems1 . This method can be applied in the development of optical filters and optical sensors to process, analyze and choose the passband of the propagation modes of an optical pulse from an non-Hermitian optical system. Non-Hermitian optical systems can be used to develop optical fiber sensors that suppress certain propagation modes of optical pulses that eventually behave as quantum noise. Such systems are described by the Nonlinear Schrödinger-like Equation with Parity-Time (PT) Symmetric Optical Potentials. There are optical fiber sensors that due to high laser intensity and frequency can produce quantum noise, such as Raman and Brillouin scattering. However, the optical fiber, for example, can be designed so that its geometry suppress certain propagation modes of the beam. We apply some results of non- Hermitian optical systems with PT symmetry to simulate optical lattice by a appropriate potential function, which among other applications, can naturally suppress certain propagation modes of an optical beam propagating through a waveguide. In other words, the optical system is modeled by a potential function in the Nonlinear Schrödinger-like Equation that one relates with the geometric aspects of the wave guides and with the optical beam interacting with the waveguide material. The paper is organized as follows: sections 1 and 2 present a brief description about nonlinear optical systems and non-Hermitian optical systems with PT symmetry. Section 3 presents a description of the dynamics of nonlinear optical pulses propagating through optical networks described by a optical potential non-Hermitian. Sections 4 and 5 present a general description of this non-Hermitian optical systems and how to get them from a more general model. Section 6 presents some conclusions and comment and the final section presents the references. Begin the abstract two lines below author names and addresses.

Highly Reliable PON Optical Splitters for Optical Access Networks in Outside Environments

NASA Astrophysics Data System (ADS)

Watanabe, Hiroshi; Araki, Noriyuki; Fujimoto, Hisashi

Broadband optical access services are spreading throughout the world, and the number of fiber to the home (FTTH) subscribers is increasing rapidly. Telecom operators are constructing passive optical networks (PONs) to provide optical access services. Externally installed optical splitters for PONs are very important passive devices in optical access networks, and they must provide satisfactory performance as outdoor plant over long periods. Therefore, we calculate the failure rate of optical access networks and assign a failure rate to the optical splitters in optical access networks. The maximum cumulative failure rate of 1 × 8 optical splitters was calculated as 0.025 for an optical access fiber length of 2.1km and a 20-year operating lifetime. We examined planar lightwave circuit (PLC) type optical splitters for use as outside plant in terms of their optical characteristics and environmental reliability. We confirmed that PLC type optical splitters have sufficient optical performance for a PON splitter and sufficient reliability as outside plant in accordance with ITU-T standard values. We estimated the lifetimes of three kinds of PLC type optical splitters by using accelerated aging tests. The estimated failure rate of these splitters installed in optical access networks was below the target value for the cumulative failure rate, and we confirmed that they have sufficient reliability to maintain the quality of the network service. We developed 1 × 8 optical splitter modules with plug and socket type optical connectors and optical fiber cords for optical aerial closures designed for use as outside plant. These technologies make it easy to install optical splitters in an aerial optical closure. The optical splitter modules have sufficient optical performance levels for PONs because the insertion loss at the commercially used wavelengths of 1.31 and 1.55µm is less than the criterion established by ITU-T Recommendation G.671 for optical splitters. We performed a temperature cycling test, and a low temperature storage and damp heat test to confirm the long-term reliability of these modules. They exhibited sufficient reliability as regards heat and moisture because the maximum loss change was less than 0.3dB.

Longitudinal evidence for anterograde trans-synaptic degeneration after optic neuritis

PubMed Central

Goodkin, Olivia; Altmann, Daniel R.; Jenkins, Thomas M.; Miszkiel, Katherine; Mirigliani, Alessia; Fini, Camilla; Gandini Wheeler-Kingshott, Claudia A. M.; Thompson, Alan J.; Ciccarelli, Olga; Toosy, Ahmed T.

2016-01-01

Abstract In multiple sclerosis, microstructural damage of normal-appearing brain tissue is an important feature of its pathology. Understanding these mechanisms is vital to help develop neuroprotective strategies. The visual pathway is a key model to study mechanisms of damage and recovery in demyelination. Anterograde trans-synaptic degeneration across the lateral geniculate nuclei has been suggested as a mechanism of tissue damage to explain optic radiation abnormalities seen in association with demyelinating disease and optic neuritis, although evidence for this has relied solely on cross-sectional studies. We therefore aimed to assess: (i) longitudinal changes in the diffusion properties of optic radiations after optic neuritis suggesting trans-synaptic degeneration; (ii) the predictive value of early optic nerve magnetic resonance imaging measures for late optic radiations changes; and (iii) the impact on visual outcome of both optic nerve and brain post-optic neuritis changes. Twenty-eight consecutive patients with acute optic neuritis and eight healthy controls were assessed visually (logMAR, colour vision, and Sloan 1.25%, 5%, 25%) and by magnetic resonance imaging, at baseline, 3, 6, and 12 months. Magnetic resonance imaging sequences performed (and metrics obtained) were: (i) optic nerve fluid-attenuated inversion-recovery (optic nerve cross-sectional area); (ii) optic nerve proton density fast spin-echo (optic nerve proton density-lesion length); (iii) optic nerve post-gadolinium T 1 -weighted (Gd-enhanced lesion length); and (iv) brain diffusion-weighted imaging (to derive optic radiation fractional anisotropy, radial diffusivity, and axial diffusivity). Mixed-effects and multivariate regression models were performed, adjusting for age, gender, and optic radiation lesion load. These identified changes over time and associations between early optic nerve measures and 1-year global optic radiation/clinical measures. The fractional anisotropy in patients’ optic radiations decreased ( P = 0.018) and radial diffusivity increased ( P = 0.002) over 1 year following optic neuritis, whereas optic radiation measures were unchanged in controls. Also, smaller cross-sectional areas of affected optic nerves at 3 months post-optic neuritis predicted lower fractional anisotropy and higher radial diffusivity at 1 year ( P = 0.007) in the optic radiations, whereas none of the inflammatory measures of the optic nerve predicted changes in optic radiations. Finally, greater Gd-enhanced lesion length at baseline and greater optic nerve proton density-lesion length at 1 year were associated with worse visual function at 1 year ( P = 0.034 for both). Neither the cross-sectional area of the affected optic nerve after optic neuritis nor the damage in optic radiations was associated with 1-year visual outcome. Our longitudinal study shows that, after optic neuritis, there is progressive damage to the optic radiations, greater in patients with early residual optic nerve atrophy, even after adjusting for optic radiation lesions. These findings provide evidence for trans-synaptic degeneration. PMID:26912640

Fiber optic crossbar switch for automatically patching optical signals

NASA Technical Reports Server (NTRS)

Bell, C. H. (Inventor)

1983-01-01

A system for automatically optically switching fiber optic data signals between a plurality of input optical fibers and selective ones of a plurality of output fibers is described. The system includes optical detectors which are connected to each of the input fibers for converting the optic data signals appearing at the respective input fibers to an RF signal. A plurality of RF to optical signal converters are arranged in rows and columns. The output of each of the optical detectors are each applied to a respective row of optical signal converted for being converters back to an optical signal when the particular optical signal converter is selectively activated by a dc voltage.

Optical system design, analysis, and production; Proceedings of the Meeting, Geneva, Switzerland, April 19-22, 1983

NASA Astrophysics Data System (ADS)

Rogers, P. J.; Fischer, R. E.

1983-01-01

Topics considered include: optical system requirements, analysis, and system engineering; optical system design using microcomputers and minicomputers; optical design theory and computer programs; optical design methods and computer programs; optical design methods and philosophy; unconventional optical design; diffractive and gradient index optical system design; optical production and system integration; and optical systems engineering. Particular attention is given to: stray light control as an integral part of optical design; current and future directions of lens design software; thin-film technology in the design and production of optical systems; aspherical lenses in optical scanning systems; the application of volume phase holograms to avionic displays; the effect of lens defects on thermal imager performance; and a wide angle zoom for the Space Shuttle.

Athermalization of resonant optical devices via thermo-mechanical feedback

DOEpatents

Rakich, Peter; Nielson, Gregory N.; Lentine, Anthony L.

2016-01-19

A passively athermal photonic system including a photonic circuit having a substrate and an optical cavity defined on the substrate, and passive temperature-responsive provisions for inducing strain in the optical cavity of the photonic circuit to compensate for a thermo-optic effect resulting from a temperature change in the optical cavity of the photonic circuit. Also disclosed is a method of passively compensating for a temperature dependent thermo-optic effect resulting on an optical cavity of a photonic circuit including the step of passively inducing strain in the optical cavity as a function of a temperature change of the optical cavity thereby producing an elasto-optic effect in the optical cavity to compensate for the thermo-optic effect resulting on an optical cavity due to the temperature change.

Optical cavity furnace for semiconductor wafer processing

DOEpatents

Sopori, Bhushan L.

2014-08-05

An optical cavity furnace 10 having multiple optical energy sources 12 associated with an optical cavity 18 of the furnace. The multiple optical energy sources 12 may be lamps or other devices suitable for producing an appropriate level of optical energy. The optical cavity furnace 10 may also include one or more reflectors 14 and one or more walls 16 associated with the optical energy sources 12 such that the reflectors 14 and walls 16 define the optical cavity 18. The walls 16 may have any desired configuration or shape to enhance operation of the furnace as an optical cavity 18. The optical energy sources 12 may be positioned at any location with respect to the reflectors 14 and walls defining the optical cavity. The optical cavity furnace 10 may further include a semiconductor wafer transport system 22 for transporting one or more semiconductor wafers 20 through the optical cavity.

Optic Nerve Lymphoma. Report of Two Cases and Review of the Literature

PubMed Central

Kim, Jennifer L.; Mendoza, Pia; Rashid, Alia; Hayek, Brent; Grossniklaus, Hans E.

2014-01-01

Lymphoma may involve the optic nerve as isolated optic nerve lymphoma or in association with CNS or systemic lymphoma. We present two biopsy-proven non-Hodgkin lymphomas of the optic nerve and compare our findings with previously reported cases. We discuss the mechanism of metastasis, classification of optic nerve involvement, clinical features, radiologic findings, optic nerve biopsy indications and techniques, histologic features, and treatments. We propose a classification system of optic nerve lymphoma: isolated optic nerve involvement, optic nerve involvement with CNS disease, optic nerve involvement with systemic disease, and optic nerve involvement with primary intraocular lymphoma. Although it is an uncommon cause of infiltrative optic neuropathy, optic nerve metastasis should be considered in patients with a history of lymphoma. The recommended approach to a patient with presumed optic nerve lymphoma includes neuroimaging, and cerebrospinal fluid evaluation as part of the initial work-up, then judicious use of optic nerve biopsy, depending on the clinical situation. PMID:25595061

All-semiconductor metamaterial-based optical circuit board at the microscale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Min, Li; Huang, Lirong, E-mail: lrhuang@hust.edu.cn

2015-07-07

The newly introduced metamaterial-based optical circuit, an analogue of electronic circuit, is becoming a forefront topic in the fields of electronics, optics, plasmonics, and metamaterials. However, metals, as the commonly used plasmonic elements in an optical circuit, suffer from large losses at the visible and infrared wavelengths. We propose here a low-loss, all-semiconductor metamaterial-based optical circuit board at the microscale by using interleaved intrinsic GaAs and doped GaAs, and present the detailed design process for various lumped optical circuit elements, including lumped optical inductors, optical capacitors, optical conductors, and optical insulators. By properly combining these optical circuit elements and arrangingmore » anisotropic optical connectors, we obtain a subwavelength optical filter, which can always hold band-stop filtering function for various polarization states of the incident electromagnetic wave. All-semiconductor optical circuits may provide a new opportunity in developing low-power and ultrafast components and devices for optical information processing.« less

Development of optical sciences in Poland

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.

2013-10-01

Research and technical communities for optics, photonics and optoelectronics is grouped in this country in several organizations and institutions. These are: Photonics Society of Poland (PSP), Polish Committee of Optoelectronics of SEP, Photonics Section of KEiT PAN, Laser Club at WAT, and Optics Section of PTF. Each of these communities keeps slightly different specificity. PSP publishes a quarterly journal Photonics Letters of Poland, stimulates international cooperation, and organizes conferences during Industrial Fairs on Innovativeness. PKOpto SEP organizes didactic diploma competitions in optoelectronics. KEiT PAN takes patronage over national conferences in laser technology, optical fiber technology and communications, and photonics applications. SO-PTF has recently taken a decision to organize a cyclic event "Polish Optical Conference". The third edition of this conference PKO'2013 was held in Sandomierz on 30.06-04.07.2013. The conference scientific and technical topics include: quantum and nonlinear optics, photon physics, optic and technology of lasers and other sources of coherent radiation, optoelectronics, optical integrated circuits, optical fibers, medical optics, instrumental optics, optical spectroscopy, optical metrology, new optical materials, applications of optics, teaching in optics. This paper reviews chosen works presented during the III Polish Optical Conference (PKO'2013), representing the research efforts at different national institutions.

Optical technology for flight control systems

NASA Technical Reports Server (NTRS)

Mayanagi, M.

1986-01-01

Optical applications to the flight control system including optical data bus, sensors, and transducers are analyzed. Examples of optical data bus include airborne light optical fiber technology (ALOFT), F-5E, YA-7D, MIL-STD-1553 fiber optic data bus and NAL-optic data bus. This NAL-optic data bus is applied to STOL, and its characteristics are stressed. Principles and advantages of optical pulse-digital transducers are discussed.

Photonic band gap materials: towards an all-optical transistor

NASA Astrophysics Data System (ADS)

Florescu, Marian

2002-05-01

The transmission of information as optical signals encoded on light waves traveling through optical fibers and optical networks is increasingly moving to shorter and shorter distance scales. In the near future, optical networking is poised to supersede conventional transmission over electric wires and electronic networks for computer-to-computer communications, chip-to-chip communications, and even on-chip communications. The ever-increasing demand for faster and more reliable devices to process the optical signals offers new opportunities in developing all-optical signal processing systems (systems in which one optical signal controls another, thereby adding "intelligence" to the optical networks). All-optical switches, two-state and many-state all-optical memories, all-optical limiters, all-optical discriminators and all-optical transistors are only a few of the many devices proposed during the last two decades. The "all-optical" label is commonly used to distinguish the devices that do not involve dissipative electronic transport and require essentially no electrical communication of information. The all-optical transistor action was first observed in the context of optical bistability [1] and consists in a strong differential gain regime, in which, for small variations in the input intensity, the output intensity has a very strong variation. This analog operation is for all-optical input what transistor action is for electrical inputs.

Design of freeform optics for an ophthalmological application

NASA Astrophysics Data System (ADS)

Sieber, Ingo; Yi, Allen; Li, Likai; Beckert, Erik; Steinkopf, Ralf; Gengenbach, Ulrich

2014-05-01

Optical freeform surfaces are gaining importance in different optical applications. A huge demand arises e.g. in the fields of automotive and medical engineering. Innovative systems often need high-quality and high-volume optics. Injectionmoulded polymer optics represents a cost-efficient solution. However, it has to be ensured that the tight requirements with respect to the system's performance are met by the replicated freeform optics. To reach this goal, it is not sufficient to only characterise the manufactured optics by peak-to-valley or rms data describing a deviation from the nominal surface. Instead, optical performance of the manufactured freeform optics has to be analysed and compared with the performance of the nominal surface. This can be done by integrating the measured surface data of the manufactured freeform optics into the optical simulation model. The feedback of the measured surface data into the model allows for a simulation of the optical performance of the optical subsystem containing the real freeform optics manufactured. Hence, conclusions can be drawn as to whether the specifications with respect to e.g. imaging quality are met by the real manufactured optics. This approach will be presented using an Alvarez-Humphrey optics as an example of a tuneable optics of an ophthalmological application. The focus of this article will be on design for manufacturing the freeform optics, the integration of the measured surface data into the optical simulation model, simulation of the optical performance, and analysis in comparison to the nominal surface.

Development of New Electro-Optic and Acousto-Optic Materials.

DTIC Science & Technology

1983-11-01

Improved materials are required for active optical devices, including electro - optic and acousto-optic modulators, switches and tunable filters, as...many microwave applications. In addition, electro - optic and acousto-optic devices are materials limited because the materials currently available are...these materials for applications involving the electro - optic effect, degenerate four-wave mixing and surface acoustic wave technology.

Role of optical computers in aeronautical control applications

NASA Technical Reports Server (NTRS)

Baumbick, R. J.

1981-01-01

The role that optical computers play in aircraft control is determined. The optical computer has the potential high speed capability required, especially for matrix/matrix operations. The optical computer also has the potential for handling nonlinear simulations in real time. They are also more compatible with fiber optic signal transmission. Optics also permit the use of passive sensors to measure process variables. No electrical energy need be supplied to the sensor. Complex interfacing between optical sensors and the optical computer is avoided if the optical sensor outputs can be directly processed by the optical computer.

Plasmon-assisted optical vias for photonic ASICS

DOEpatents

Skogen, Erik J.; Vawter, Gregory A.; Tauke-Pedretti, Anna

2017-03-21

The present invention relates to optical vias to optically connect multilevel optical circuits. In one example, the optical via includes a surface plasmon polariton waveguide, and a first optical waveguide formed on a first substrate is coupled to a second optical waveguide formed on a second substrate by the surface plasmon polariton waveguide. In some embodiments, the first optical waveguide includes a transition region configured to convert light from an optical mode to a surface plasmon polariton mode or from a surface plasmon polariton mode to an optical mode.

Research Studies on Advanced Optical Module/Head Designs for Optical Data Storage

NASA Technical Reports Server (NTRS)

1992-01-01

Preprints are presented from the recent 1992 Optical Data Storage meeting in San Jose. The papers are divided into the following topical areas: Magneto-optical media (Modeling/design and fabrication/characterization/testing); Optical heads (holographic optical elements); and Optical heads (integrated optics). Some representative titles are as follow: Diffraction analysis and evaluation of several focus and track error detection schemes for magneto-optical disk systems; Proposal for massively parallel data storage system; Transfer function characteristics of super resolving systems; Modeling and measurement of a micro-optic beam deflector; Oxidation processes in magneto-optic and related materials; and A modal analysis of lamellar diffraction gratings in conical mountings.

Optical analog-to-digital converter

DOEpatents

Vawter, G Allen [Corrales, NM; Raring, James [Goleta, CA; Skogen, Erik J [Albuquerque, NM

2009-07-21

An optical analog-to-digital converter (ADC) is disclosed which converts an input optical analog signal to an output optical digital signal at a sampling rate defined by a sampling optical signal. Each bit of the digital representation is separately determined using an optical waveguide interferometer and an optical thresholding element. The interferometer uses the optical analog signal and the sampling optical signal to generate a sinusoidally-varying output signal using cross-phase-modulation (XPM) or a photocurrent generated from the optical analog signal. The sinusoidally-varying output signal is then digitized by the thresholding element, which includes a saturable absorber or at least one semiconductor optical amplifier, to form the optical digital signal which can be output either in parallel or serially.

Optical data latch

DOEpatents

Vawter, G Allen [Corrales, NM

2010-08-31

An optical data latch is formed on a substrate from a pair of optical logic gates in a cross-coupled arrangement in which optical waveguides are used to couple an output of each gate to an photodetector input of the other gate. This provides an optical bi-stability which can be used to store a bit of optical information in the latch. Each optical logic gate, which can be an optical NOT gate (i.e. an optical inverter) or an optical NOR gate, includes a waveguide photodetector electrically connected in series with a waveguide electroabsorption modulator. The optical data latch can be formed on a III-V compound semiconductor substrate (e.g. an InP or GaAs substrate) from III-V compound semiconductor layers. A number of optical data latches can be cascaded to form a clocked optical data shift register.

Fiber optic monitoring device

DOEpatents

Samborsky, James K.

1993-01-01

A device for the purpose of monitoring light transmissions in optical fibers comprises a fiber optic tap that optically diverts a fraction of a transmitted optical signal without disrupting the integrity of the signal. The diverted signal is carried, preferably by the fiber optic tap, to a lens or lens system that disperses the light over a solid angle that facilitates viewing. The dispersed light indicates whether or not the monitored optical fiber or system of optical fibers is currently transmitting optical information.

Gregorian optical system with non-linear optical technology for protection against intense optical transients

DOEpatents

Ackermann, Mark R [Albuquerque, NM; Diels, Jean-Claude M [Albuquerque, NM

2007-06-26

An optical system comprising a concave primary mirror reflects light through an intermediate focus to a secondary mirror. The secondary mirror re-focuses the image to a final image plane. Optical limiter material is placed near the intermediate focus to optically limit the intensity of light so that downstream components of the optical system are protected from intense optical transients. Additional lenses before and/or after the intermediate focus correct optical aberrations.

The Tuning of Optical Properties of Nanoscale MOFs-Based Thin Film through Post-Modification.

PubMed

Yin, Wenchang; Tao, Cheng-An; Zou, Xiaorong; Wang, Fang; Qu, Tianlian; Wang, Jianfang

2017-08-29

Optical properties, which determine the application of optical devices in different fields, are the most significant properties of optical thin films. In recent years, Metal-organic framework (MOF)-based optical thin films have attracted increasing attention because of their novel optical properties and important potential applications in optical and photoelectric devices, especially optical thin films with tunable optical properties. This study reports the first example of tuning the optical properties of a MOF-based optical thin film via post-modification. The MOF-based optical thin film was composed of NH₂-MIL-53(Al) nanorods (NRs) (MIL: Materials from Institute Lavoisier), and was constructed via a spin-coating method. Three aldehydes with different lengths of carbon chains were chosen to modify the MOF optical thin film to tune their optical properties. After post-modification, the structural color of the NH₂-MIL-53(Al) thin film showed an obvious change from purple to bluish violet and cyan. The reflection spectrum and the reflectivity also altered in different degrees. The effective refractive index ( n eff ) of MOFs thin film can also be tuned from 1.292 to 1.424 at a wavelength of 750 nm. The success of tuning of the optical properties of MOFs thin films through post-modification will make MOFs optical thin films meet different needs of optical properties in various optical and optoelectronic devices.

The Tuning of Optical Properties of Nanoscale MOFs-Based Thin Film through Post-Modification

PubMed Central

Zou, Xiaorong; Wang, Fang; Qu, Tianlian; Wang, Jianfang

2017-01-01

Optical properties, which determine the application of optical devices in different fields, are the most significant properties of optical thin films. In recent years, Metal-organic framework (MOF)-based optical thin films have attracted increasing attention because of their novel optical properties and important potential applications in optical and photoelectric devices, especially optical thin films with tunable optical properties. This study reports the first example of tuning the optical properties of a MOF-based optical thin film via post-modification. The MOF-based optical thin film was composed of NH2-MIL-53(Al) nanorods (NRs) (MIL: Materials from Institute Lavoisier), and was constructed via a spin-coating method. Three aldehydes with different lengths of carbon chains were chosen to modify the MOF optical thin film to tune their optical properties. After post-modification, the structural color of the NH2-MIL-53(Al) thin film showed an obvious change from purple to bluish violet and cyan. The reflection spectrum and the reflectivity also altered in different degrees. The effective refractive index (neff) of MOFs thin film can also be tuned from 1.292 to 1.424 at a wavelength of 750 nm. The success of tuning of the optical properties of MOFs thin films through post-modification will make MOFs optical thin films meet different needs of optical properties in various optical and optoelectronic devices. PMID:28850057

Improving the Total Impulse Capability of the NSTAR Ion Thruster With Thick-Accelerator-Grid Ion Optics

NASA Technical Reports Server (NTRS)

Soulas, George C.

2001-01-01

The results of performance tests with thick-accelerator-grid (TAG) ion optics are presented. TAG ion optics utilize a 50 percent thicker accelerator grid to double ion optics' service life. NSTAR ion optics were also tested to provide a baseline performance for comparison. Impingement-limited total voltages for the TAG ion optics were only 0 to 15 V higher than those of the NSTAR ion optics. Electron backstreaming limits for the TAG ion optics were 3 to 9 V higher than those for the NSTAR optics due to the increased accelerator grid thickness for the TAG ion optics. Screen grid ion transparencies for the TAG ion optics were only about 2 percent lower than those for the NSTAR optics, reflecting the lower physical screen grid open area fraction of the TAG ion optics. Accelerator currents for the TAG ion optics were 19 to 43 percent greater than those for the NSTAR ion optics due, in part, to a sudden increase in accelerator current during TAG ion optics' performance tests for unknown reasons and to the lower-than-nominal accelerator aperture diameters. Beam divergence half-angles that enclosed 95 percent of the total beam current and beam divergence thrust correction factors for the TAG ion optics were within 2 degrees and 1 percent, respectively, of those for the NSTAR ion optics.

Optical properties of mouse brain tissue after optical clearing with FocusClear™

NASA Astrophysics Data System (ADS)

Moy, Austin J.; Capulong, Bernard V.; Saager, Rolf B.; Wiersma, Matthew P.; Lo, Patrick C.; Durkin, Anthony J.; Choi, Bernard

2015-09-01

Fluorescence microscopy is commonly used to investigate disease progression in biological tissues. Biological tissues, however, are strongly scattering in the visible wavelengths, limiting the application of fluorescence microscopy to superficial (<200 μm) regions. Optical clearing, which involves incubation of the tissue in a chemical bath, reduces the optical scattering in tissue, resulting in increased tissue transparency and optical imaging depth. The goal of this study was to determine the time- and wavelength-resolved dynamics of the optical scattering properties of rodent brain after optical clearing with FocusClear™. Light transmittance and reflectance of 1-mm mouse brain sections were measured using an integrating sphere before and after optical clearing and the inverse adding doubling algorithm used to determine tissue optical scattering. The degree of optical clearing was quantified by calculating the optical clearing potential (OCP), and the effects of differing OCP were demonstrated using the optical histology method, which combines tissue optical clearing with optical imaging to visualize the microvasculature. We observed increased tissue transparency with longer optical clearing time and an analogous increase in OCP. Furthermore, OCP did not vary substantially between 400 and 1000 nm for increasing optical clearing durations, suggesting that optical histology can improve ex vivo visualization of several fluorescent probes.

Refractive index retrieving of polarization maintaining optical fibers

NASA Astrophysics Data System (ADS)

Ramadan, W. A.; Wahba, H. H.; Shams El-Din, M. A.; Abd El-Sadek, I. G.

2018-01-01

In this paper, the cross-section images, of two different types of polarization maintaining (PM) optical fibers, are employed to estimate the optical phase variation due to transverse optical rays passing through these optical fibers. An adaptive algorithm is proposed to recognize the different areas constituting the PM optical fibers cross-sections. These areas are scanned by a transverse beam to calculate the optical paths for given values of refractive indices. Consequently, the optical phases across the PM optical fibers could be recovered. PM optical fiber is immersed in a matching fluid and set in the object arm of Mach-Zehnder interferometer. The produced interferograms are analyzed to extract the optical phases caused by the PM optical fibers. The estimated optical phases could be optimized to be in good coincidence with experimentally extracted ones. This has been achieved through changing of the PM optical fibers refractive indices to retrieve the correct values. The correct refractive indices values are confirmed by getting the best fit between the estimated and the extracted optical phases. The presented approach is a promising one because it provides a quite direct and accurate information about refractive index, birefringence and beat length of PM optical fibers comparing with different techniques handle the same task.

A novel all-optical label processing for OPS networks based on multiple OOC sequences from multiple-groups OOC

NASA Astrophysics Data System (ADS)

Qiu, Kun; Zhang, Chongfu; Ling, Yun; Wang, Yibo

2007-11-01

This paper proposes an all-optical label processing scheme using multiple optical orthogonal codes sequences (MOOCS) for optical packet switching (OPS) (MOOCS-OPS) networks, for the first time to the best of our knowledge. In this scheme, the multiple optical orthogonal codes (MOOC) from multiple-groups optical orthogonal codes (MGOOC) are permuted and combined to obtain the MOOCS for the optical labels, which are used to effectively enlarge the capacity of available optical codes for optical labels. The optical label processing (OLP) schemes are reviewed and analyzed, the principles of MOOCS-based optical labels for OPS networks are given, and analyzed, then the MOOCS-OPS topology and the key realization units of the MOOCS-based optical label packets are studied in detail, respectively. The performances of this novel all-optical label processing technology are analyzed, the corresponding simulation is performed. These analysis and results show that the proposed scheme can overcome the lack of available optical orthogonal codes (OOC)-based optical labels due to the limited number of single OOC for optical label with the short code length, and indicate that the MOOCS-OPS scheme is feasible.

Fibre-optic nonlinear optical microscopy and endoscopy.

PubMed

Fu, L; Gu, M

2007-06-01

Nonlinear optical microscopy has been an indispensable laboratory tool of high-resolution imaging in thick tissue and live animals. Rapid developments of fibre-optic components in terms of growing functionality and decreasing size provide enormous opportunities for innovations in nonlinear optical microscopy. Fibre-based nonlinear optical endoscopy is the sole instrumentation to permit the cellular imaging within hollow tissue tracts or solid organs that are inaccessible to a conventional optical microscope. This article reviews the current development of fibre-optic nonlinear optical microscopy and endoscopy, which includes crucial technologies for miniaturized nonlinear optical microscopy and their embodiments of endoscopic systems. A particular attention is given to several classes of photonic crystal fibres that have been applied to nonlinear optical microscopy due to their unique properties for ultrashort pulse delivery and signal collection. Furthermore, fibre-optic nonlinear optical imaging systems can be classified into portable microscopes suitable for imaging behaving animals, rigid endoscopes that allow for deep tissue imaging with minimally invasive manners, and flexible endoscopes enabling imaging of internal organs. Fibre-optic nonlinear optical endoscopy is coming of age and a paradigm shift leading to optical microscope tools for early cancer detection and minimally invasive surgery.

Optical bistability for optical signal processing and computing

NASA Astrophysics Data System (ADS)

Peyghambarian, N.; Gibbs, H. M.

1985-02-01

Optical bistability (OB) is a phenomenon in which a nonlinear medium responds to an optical input beam by changing its transmission abruptly from one value to another. A 'nonlinear medium' is a medium in which the index of refraction depends on the incident light intensity. A device is said to be optically bistable if two stable output states exist for the same value of the input. Optically bistable devices can perform a number of logic functions related to optical memory, optical transistor, optical discriminator, optical limiter, optical oscillator, and optical gate. They also have the potential for subpicosecond switching, greatly exceeding the capability of electronics. This potential is one of several advantages of optical data processing over electronic processing. Other advantages are greater immunity to electromagnetic interference and crosstalk, and highly parallel processing capability. The present investigation is mainly concerned with all-optical etalon devices. The considered materials, include GaAs, ZnS and ZnSe, CuCl, InSb, InAs, and CdS.

Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.

2016-03-29

A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

Micro-Fresnel Zone Plate Optical Devices Using Densely Accumulated Ray Points

NASA Technical Reports Server (NTRS)

Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2011-01-01

An embodiment generally relates to an optical device suitable for use with an optical medium for the storage and retrieval of data. The optical device includes an illumination means for providing a beam of optical radiation of wavelength .lamda. and an optical path that the beam of optical radiation follows. The optical device also includes a diffractive optical element defined by a plurality of annular sections. The plurality of annular sections having a first material alternately disposed with a plurality of annular sections comprising a second material. The diffractive optical element generates a plurality of focal points and densely accumulated ray points with phase contrast phenomena and the optical medium is positioned at a selected focal point or ray point of the diffractive optical element.

Optical computing and neural networks; Proceedings of the Meeting, National Chiao Tung Univ., Hsinchu, Taiwan, Dec. 16, 17, 1992

NASA Technical Reports Server (NTRS)

Hsu, Ken-Yuh (Editor); Liu, Hua-Kuang (Editor)

1992-01-01

The present conference discusses optical neural networks, photorefractive nonlinear optics, optical pattern recognition, digital and analog processors, and holography and its applications. Attention is given to bifurcating optical information processing, neural structures in digital halftoning, an exemplar-based optical neural net classifier for color pattern recognition, volume storage in photorefractive disks, and microlaser-based compact optical neuroprocessors. Also treated are the optical implementation of a feature-enhanced optical interpattern-associative neural network model and its optical implementation, an optical pattern binary dual-rail logic gate module, a theoretical analysis for holographic associative memories, joint transform correlators, image addition and subtraction via the Talbot effect, and optical wavelet-matched filters. (No individual items are abstracted in this volume)

Optical computing and neural networks; Proceedings of the Meeting, National Chiao Tung Univ., Hsinchu, Taiwan, Dec. 16, 17, 1992

NASA Astrophysics Data System (ADS)

Hsu, Ken-Yuh; Liu, Hua-Kuang

The present conference discusses optical neural networks, photorefractive nonlinear optics, optical pattern recognition, digital and analog processors, and holography and its applications. Attention is given to bifurcating optical information processing, neural structures in digital halftoning, an exemplar-based optical neural net classifier for color pattern recognition, volume storage in photorefractive disks, and microlaser-based compact optical neuroprocessors. Also treated are the optical implementation of a feature-enhanced optical interpattern-associative neural network model and its optical implementation, an optical pattern binary dual-rail logic gate module, a theoretical analysis for holographic associative memories, joint transform correlators, image addition and subtraction via the Talbot effect, and optical wavelet-matched filters. (No individual items are abstracted in this volume)

Optical NAND gate

DOEpatents

Skogen, Erik J [Albuquerque, NM; Raring, James [Goleta, CA; Tauke-Pedretti, Anna [Albuquerque, NM

2011-08-09

An optical NAND gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator and a photodetector. One pair of the optical waveguide devices is electrically connected in parallel to operate as an optical AND gate; and the other pair of the optical waveguide devices is connected in series to operate as an optical NOT gate (i.e. an optical inverter). The optical NAND gate utilizes two digital optical inputs and a continuous light input to provide a NAND function output. The optical NAND gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers.

PubMed

Su, Hui; Kondratko, Piotr; Chuang, Shun L

2006-05-29

We investigate variable optical delay of a microwave modulated optical beam in semiconductor optical amplifier/absorber waveguides with population oscillation (PO) and nearly degenerate four-wave-mixing (NDFWM) effects. An optical delay variable between 0 and 160 ps with a 1.0 GHz bandwidth is achieved in an InGaAsP/InP semiconductor optical amplifier (SOA) and shown to be electrically and optically controllable. An analytical model of optical delay is developed and found to agree well with the experimental data. Based on this model, we obtain design criteria to optimize the delay-bandwidth product of the optical delay in semiconductor optical amplifiers and absorbers.

Micro-optics technology and sensor systems applications

NASA Technical Reports Server (NTRS)

Gal, George; Herman, B.; Anderson, W.; Whitney, R.; Morrow, H.

1993-01-01

The current generation of electro-optical sensors utilizing refractive and reflective optical elements require sophisticated, complex, and expensive designs. Advanced-technology-based electro-optical sensors of minimum size and weight require miniaturization of optical, electrical, and mechanical devices with an increasing trend toward integration of various components. Micro-optics technology has the potential in a number of areas to simplify optical design with improved performance. This includes internally cooled apertures, hybrid optical design, microlenses, dispersive multicolor microlenses, active dither, electronically controlled optical beam steer, and microscopic integration of micro-optics, detectors, and signal processing layers. This paper describes our approach to the development of micro-optics technology with our main emphasis for sensors applications.

Systems and methods for enhancing optical information

DOEpatents

DeVore, Peter Thomas Setsuda; Chou, Jason T.

2018-01-02

An Optical Information Transfer Enhancer System includes a first system for producing an information bearing first optical wave that is impressed with a first information having a first information strength wherein the first optical wave has a first shape. A second system produces a second optical wave. An information strength enhancer module receives the first and said second optical waves and impresses the first optical wave upon the second optical wave via cross-phase modulation (XPM) to produce an information-strength-enhanced second optical wave having a second information strength that is greater than the first information strength of the first optical wave. Following a center-wavelength changer by an Optical Information Transfer Enhancer System improves its performance.

Microwave assisted reconstruction of optical interferograms for distributed fiber optic sensing.

PubMed

Huang, Jie; Hua, Lei; Lan, Xinwei; Wei, Tao; Xiao, Hai

2013-07-29

This paper reports a distributed fiber optic sensing technique through microwave assisted separation and reconstruction of optical interferograms in spectrum domain. The approach involves sending a microwave-modulated optical signal through cascaded fiber optic interferometers. The microwave signal was used to resolve the position and reflectivity of each sensor along the optical fiber. By sweeping the optical wavelength and detecting the modulation signal, the optical spectrum of each sensor can be reconstructed. Three cascaded fiber optic extrinsic Fabry-Perot interferometric sensors were used to prove the concept. Their microwave-reconstructed interferogram matched well with those recorded individually using an optical spectrum analyzer. The application in distributed strain measurement has also been demonstrated.

Observation of orbital angular momentum transfer between acoustic and optical vortices in optical fiber.

PubMed

Dashti, Pedram Z; Alhassen, Fares; Lee, Henry P

2006-02-03

Acousto-optic interaction in optical fiber is examined from the perspective of copropagating optical and acoustic vortex modes. Calculation of the acousto-optic coupling coefficient between different optical modes leads to independent conservation of spin and orbital angular momentum of the interacting photons and phonons. We show that the orbital angular momentum of the acoustic vortex can be transferred to a circularly polarized fundamental optical mode to form a stable optical vortex in the fiber carrying orbital angular momentum. The technique provides a useful way of generating stable optical vortices in the fiber medium.

Method of lightening radiation darkened optical elements

DOEpatents

Reich, Frederich R.; Schwankoff, Albert R.

1980-01-01

A method of lightening a radiation-darkened optical element in wich visible optical energy or electromagnetic radiation having a wavelength in the range of from about 2000 to about 20,000 angstroms is directed into the radiation-darkened optical element; the method may be used to lighten radiation-darkened optical element in-situ during the use of the optical element to transmit data by electronically separating the optical energy from the optical output by frequency filtering, data cooling, or interlacing the optic energy between data intervals.

The Optics Option: Preparing For A Career In Optics

NASA Astrophysics Data System (ADS)

Hartmann, Rudolf

1989-04-01

We live in a visual world. Without vision, our perception of the environment would be severely limited. Visual stimuli are seen, recorded, and processed in many different ways. Astronomy, the process of imaging distant objects, and microscopy, the process of magnifying minute detail, are extensions of vision. Other extensions of vision include seeing things in different spectra, processing images for enhancement, making decisions automatically, and guiding and controlling sophisticated, complex industrial and military equipment. Optics is the study of this vision and its applications. Optics is a fascinating field that is growing rapidly. Students and practitioners of optics are attracted to the field for a variety of reasons. Hobbies such as photography, astronomy, and video recording, as well as academic pursuits, such as a high school physics or science project, may spawn an interest in optics; however, college training is the cornerstone of an optics career. Optics is part of physics, and as such, requires coursework in the areas of geometrical optics, physical optics, spectroscopy, electricity, magnetism, and solid state physics. In addition, mathematics is extremely important for optics design, analysis, and modeling. Optics is the successful synergism of these many disciplines. Many colleges and universities offer undergraduate and graduate optics curricula. Rochester University's Institute of Optics and the Optical Sciences Center of the University of Arizona are the most prestigious of these institutions. Further, such societies as the Optical Society of America (OSA) and the International Society for Optical Engineering (SPIE) offer a wide variety of valuable short courses, tutorials, seminars, and papers at conferences that are held several times a year. Traditional optics fields, such as optometry, the examination of the eye and correction of its defects, or ophthalmology, the study of disease and treatment of the eye, are optics-oriented careers. Exciting new fields, such as optical communication, optical computing, Phase conjugation, adaptive optics, and holography, are expanding the scope of optics technologies. Development of sophisticated military EO systems presents one of the greatest opportunities and challenges in the optics world today.

Thermal/structural/optical integrated design for optical sensor mounted on unmanned aerial vehicle

NASA Astrophysics Data System (ADS)

Zhang, Gaopeng; Yang, Hongtao; Mei, Chao; Wu, Dengshan; Shi, Kui

2016-01-01

With the rapid development of science and technology and the promotion of many local wars in the world, altitude optical sensor mounted on unmanned aerial vehicle is more widely applied in the airborne remote sensing, measurement and detection. In order to obtain high quality image of the aero optical remote sensor, it is important to analysis its thermal-optical performance on the condition of high speed and high altitude. Especially for the key imaging assembly, such as optical window, the temperature variation and temperature gradient can result in defocus and aberrations in optical system, which will lead to the poor quality image. In order to improve the optical performance of a high speed aerial camera optical window, the thermal/structural/optical integrated design method is developed. Firstly, the flight environment of optical window is analyzed. Based on the theory of aerodynamics and heat transfer, the convection heat transfer coefficient is calculated. The temperature distributing of optical window is simulated by the finite element analysis software. The maximum difference in temperature of the inside and outside of optical window is obtained. Then the deformation of optical window under the boundary condition of the maximum difference in temperature is calculated. The optical window surface deformation is fitted in Zernike polynomial as the interface, the calculated Zernike fitting coefficients is brought in and analyzed by CodeV Optical Software. At last, the transfer function diagrams of the optical system on temperature field are comparatively analyzed. By comparing and analyzing the result, it can be obtained that the optical path difference caused by thermal deformation of the optical window is 138.2 nm, which is under PV ≤1 4λ . The above study can be used as an important reference for other optical window designs.

Applications of Nano-optics.

PubMed

Zhou, Changhe; Fainman, Yeshaiahu; Sheng, Yunlong

2011-11-01

As nanoscale fabrication techniques advance, nano-optics continues to offer enabling solutions to numerous practical applications for information optics. This Applied Optics feature issue focuses on the Application of Nano-optics. © 2011 Optical Society of America

Attenuator And Conditioner

DOEpatents

Anderson, Gene R.; Armendariz, Marcelino G.; Carson, Richard F.; Bryan, Robert P.; Duckett, III, Edwin B.; Kemme, Shanalyn Adair; McCormick, Frederick B.; Peterson, David W.

2006-04-04

An apparatus and method of attenuating and/or conditioning optical energy for an optical transmitter, receiver or transceiver module is disclosed. An apparatus for attenuating the optical output of an optoelectronic connector including: a mounting surface; an array of optoelectronic devices having at least a first end; an array of optical elements having at least a first end; the first end of the array of optical elements optically aligned with the first end of the array of optoelectronic devices; an optical path extending from the first end of the array of optoelectronic devices and ending at a second end of the array of optical elements; and an attenuator in the optical path for attenuating the optical energy emitted from the array of optoelectronic devices. Alternatively, a conditioner may be adapted in the optical path for conditioning the optical energy emitted from the array of optoelectronic devices.

Reconfigurable optical-to-optical frequency conversion method and apparatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zortman, William A.; Lentine, Anthony L.

A photonic device is provided for impressing a modulation pattern on an optical carrier. The device includes a unit in which a photodetector and an optical microresonator are monolithically integrated. The device further includes an optical waveguide evanescently coupled to the optical microresonator and having at least an upstream portion configured to carry at least one optical carrier toward the microresonator. The optical microresonator is tunable so as to resonate with the optical carrier frequency. The optical microresonator and the photodetector are mutually coupled such that in operation, charge carriers photogenerated in the photodetector are injected into the microresonator, wheremore » the photocurrent changes the resonant conditions. In some embodiments the device is operable as an optical-to-optical frequency converter. In other embodiments the device is operable as an oscillator.« less

Time-reversed wave mixing in nonlinear optics

PubMed Central

Zheng, Yuanlin; Ren, Huaijin; Wan, Wenjie; Chen, Xianfeng

2013-01-01

Time-reversal symmetry is important to optics. Optical processes can run in a forward or backward direction through time when such symmetry is preserved. In linear optics, a time-reversed process of laser emission can enable total absorption of coherent light fields inside an optical cavity of loss by time-reversing the original gain medium. Nonlinearity, however, can often destroy such symmetry in nonlinear optics, making it difficult to study time-reversal symmetry with nonlinear optical wave mixings. Here we demonstrate time-reversed wave mixings for optical second harmonic generation (SHG) and optical parametric amplification (OPA) by exploring this well-known but underappreciated symmetry in nonlinear optics. This allows us to observe the annihilation of coherent beams. Our study offers new avenues for flexible control in nonlinear optics and has potential applications in efficient wavelength conversion, all-optical computing. PMID:24247906

Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

NASA Technical Reports Server (NTRS)

Carman, Gregory P. (Inventor); Mohanchandra, Panduranga K. (Inventor); Emmons, Michael C. (Inventor); Richards, William Lance (Inventor)

2016-01-01

The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

Baseline demographics, clinical features, and treatment protocols of 240 patients with optic neuropathy: experiences from a neuro-ophthalmological clinic in the Aegean region of Turkey.

PubMed

Karti, Omer; Karti, Dilek Top; Kilic, İlay Hilal; Gokcay, Figen; Celebisoy, Nese

2017-12-19

To analyze the demographic patterns, clinical characteristics, and treatment protocols of optic neuropathies. The hospital data of patients with optic neuropathy admitted to the Department of Neuro-ophthalmology in a tertiary referral center in Turkey between January 2010 to January 2017 were retrospectively analyzed. Demographic patterns, clinical features, treatment protocols, and the natural disease courses were assessed. The total number of patients with optic neuropathy seen over this period was 240, which consist of 43 with idiopathic optic neuritis (17.9%), 40 with multiple sclerosis-related optic neuritis (16.7%), 12 with chronic relapsing inflammatory optic neuritis (5.0%), 12 with atypical optic neuritis (5.0%), 11 with neuromyelitis optica spectrum disorders-related optic neuritis (4.6%), 90 with non-arteritic ischemic optic neuropathy (37.5%), 4 with arteritic ischemic optic neuropathy (1.7%), 10 with traumatic optic neuropathy (4.1%), 6 with compressive optic neuropathy (2.5%), and 12 with mitochondrial optic neuropathy [9 with toxic optic neuropathy (3.7%) and 3 with Leber's hereditary optic neuropathy (1.2%)]. There were 101 males (42%) and 139 females (58%). The mean age was 43.34 ± 15.86 years. This study reported the demographics, clinical characteristics, and treatment protocols of optic neuropathies in a neuro-ophthalmology specialty clinic at a tertiary referral center in Turkey during the past decade. The data may be useful in assessing the global status of optic neuropathies.

Fiber-handling robot and optical connection mechanisms for automatic cross-connection of multiple optical connectors

NASA Astrophysics Data System (ADS)

Mizukami, Masato; Makihara, Mitsuhiro

2013-07-01

Conventionally, in intelligent buildings in a metropolitan area network and in small-scale facilities in the optical access network, optical connectors are joined manually using an optical connection board and a patch panel. In this manual connection approach, mistakes occur due to discrepancies between the actual physical settings of the connections and their management because these processes are independent. Moreover, manual cross-connection is time-consuming and expensive because maintenance personnel must be dispatched to remote places to correct mistakes. We have developed a fiber-handling robot and optical connection mechanisms for automatic cross-connection of multiple optical connectors, which are the key elements of automatic optical fiber cross-connect equipment. We evaluate the performance of the equipment, such as its optical characteristics and environmental specifications. We also devise new optical connection mechanisms that enable the automated optical fiber cross-connect module to handle and connect angled physical contact (APC) optical connector plugs. We evaluate the performance of the equipment, such as its optical characteristics. The evaluation results confirm that the automated optical fiber cross-connect equipment can connect APC connectors with low loss and high return loss, indicating that the automated optical fiber cross-connect equipment is suitable for practical use in intelligent buildings and optical access networks.

Comparison of primary optics in amonix CPV arrays

NASA Astrophysics Data System (ADS)

Nayak, Aditya; Kinsey, Geoffrey S.; Liu, Mingguo; Bagienski, William; Garboushian, Vahan

2012-10-01

The Amonix CPV system utilizes an acrylic Fresnel lens Primary Optical Element (POE) and a reflective Secondary Optical Element (SOE). Improvements in the optical design have contributed to more than 10% increase in rated power last year. In order to further optimize the optical power path, Amonix is looking at various trade-offs in optics, including, concentration, optical materials, reliability, and cost. A comparison of optical materials used for manufacturing the primary optical element and optical design trade off's used to maximize power output will be presented. Optimization of the power path has led to the demonstration of a module lens-area efficiency of 35% in outdoor testing at Amonix.

Large optics inspection, tilting, and washing stand

DOEpatents

Ayers, Marion Jay [Brentwood, CA; Ayers, Shannon Lee [Brentwood, CA

2010-08-24

A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

Large optics inspection, tilting, and washing stand

DOEpatents

Ayers, Marion Jay; Ayers, Shannon Lee

2012-10-09

A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

Active optical zoom system

DOEpatents

Wick, David V.

2005-12-20

An active optical zoom system changes the magnification (or effective focal length) of an optical imaging system by utilizing two or more active optics in a conventional optical system. The system can create relatively large changes in system magnification with very small changes in the focal lengths of individual active elements by leveraging the optical power of the conventional optical elements (e.g., passive lenses and mirrors) surrounding the active optics. The active optics serve primarily as variable focal-length lenses or mirrors, although adding other aberrations enables increased utility. The active optics can either be LC SLMs, used in a transmissive optical zoom system, or DMs, used in a reflective optical zoom system. By appropriately designing the optical system, the variable focal-length lenses or mirrors can provide the flexibility necessary to change the overall system focal length (i.e., effective focal length), and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses. The active optics can provide additional flexibility by allowing magnification to occur anywhere within the FOV of the system, not just on-axis as in a conventional system.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, J.D.

1997-05-06

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion. 3 figs.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, Jeffrey D.

1997-01-01

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion.

Interchip link system using an optical wiring method.

PubMed

Cho, In-Kui; Ryu, Jin-Hwa; Jeong, Myung-Yung

2008-08-15

A chip-scale optical link system is presented with a transmitter/receiver and optical wire link. The interchip link system consists of a metal optical bench, a printed circuit board module, a driver/receiver integrated circuit, a vertical cavity surface-emitting laser/photodiode array, and an optical wire link composed of plastic optical fibers (POFs). We have developed a downsized POF and an optical wiring method that allows on-site installation with a simple annealing as optical wiring technologies for achieving high-density optical interchip interconnection within such devices. Successful data transfer measurements are presented.

Current developments in optical engineering and diffraction phenomena; Proceedings of the Meeting, San Diego, CA, Aug. 21, 22, 1986

NASA Astrophysics Data System (ADS)

Fischer, Robert E.; Smith, Warren J.; Harvey, James

1986-01-01

Papers dealing with current materials for gradient-index optics, an intelligent data-base system for optical designers; tilted mirror systems; a null-lens design approach for centrally obscured components; the use of the vector aberration theory to optimize an unobscured optical system; multizone bifocal contact lens design; and the concentric meniscus element are presented. Topics discussed include optical manufacturing in the Far East; the optical performance of molded-glass lenses for optical memory applications; through-wafer optical interconnects for multiwafer wafer-scale integrated architecture; optical thin-flim monitoring using optical fibers; aerooptical testing; optical inspection; and a system analysis program for a 32K microcomputer. Consideration is given to various theories, algorithms, and applications of diffraction, a vector formulation of a ray-equivalent method for Gaussian beam propagation; Fourier optical analysis of aberrations in focused laser beams; holography and moire interferometry; and phase-conjugate optical correctors for diffraction-limited applications.

Chemical, biochemical, and environmental fiber sensors III; Proceedings of the Meeting, Boston, MA, Sept. 4, 5, 1991

NASA Astrophysics Data System (ADS)

Lieberman, Robert A.

Various papers on chemical, biochemical, and environmental fiber sensors are presented. Individual topics addressed include: fiber optic pressure sensor for combustion monitoring and control, viologen-based fiber optic oxygen sensors, renewable-reagent fiber optic sensor for ocean pCO2, transition metal complexes as indicators for a fiber optic oxygen sensor, fiber optic pH measurements using azo indicators, simple reversible fiber optic chemical sensors using solvatochromic dyes, totally integrated optical measuring sensors, integrated optic biosensor for environmental monitoring, radiation dosimetry using planar waveguide sensors, optical and piezoelectric analysis of polymer films for chemical sensor characterization, source polarization effects in an optical fiber fluorosensor, lens-type refractometer for on-line chemical analysis, fiber optic hydrocarbon sensor system, chemical sensors for environmental monitoring, optical fibers for liquid-crystal sensing and logic devices, suitability of single-mode fluoride fibers for evanescent-wave sensing, integrated modules for fiber optic sensors, optoelectronic sensors based on narrowband A3B5 alloys, fiber Bragg grating chemical sensor.

Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

NASA Astrophysics Data System (ADS)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

2015-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)

2006-01-01

Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

Compound semiconductor optical waveguide switch

DOEpatents

Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

2003-06-10

An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

Optical system and method for gas detection and monitoring

NASA Technical Reports Server (NTRS)

Polzin, Kurt A. (Inventor); Sinko, John Elihu (Inventor); Korman, Valentin (Inventor); Witherow, William K. (Inventor); Hendrickson, Adam Gail (Inventor)

2011-01-01

A free-space optical path of an optical interferometer is disposed in an environment of interest. A light beam is guided to the optical interferometer using a single-mode optical fiber. The light beam traverses the interferometer's optical path. The light beam guided to the optical path is combined with the light beam at the end of the optical path to define an output light. A temporal history of the output light is recorded.

Microsystem enabled photovoltaic modules and systems

DOEpatents

Nielson, Gregory N; Sweatt, William C; Okandan, Murat

2015-05-12

A microsystem enabled photovoltaic (MEPV) module including: an absorber layer; a fixed optic layer coupled to the absorber layer; a translatable optic layer; a translation stage coupled between the fixed and translatable optic layers; and a motion processor electrically coupled to the translation stage to controls motion of the translatable optic layer relative to the fixed optic layer. The absorber layer includes an array of photovoltaic (PV) elements. The fixed optic layer includes an array of quasi-collimating (QC) micro-optical elements designed and arranged to couple incident radiation from an intermediate image formed by the translatable optic layer into one of the PV elements such that it is quasi-collimated. The translatable optic layer includes an array of focusing micro-optical elements corresponding to the QC micro-optical element array. Each focusing micro-optical element is designed to produce a quasi-telecentric intermediate image from substantially collimated radiation incident within a predetermined field of view.

All-optical clocked flip-flops and random access memory cells using the nonlinear polarization rotation effect of low-polarization-dependent semiconductor optical amplifiers

NASA Astrophysics Data System (ADS)

Wang, Yongjun; Liu, Xinyu; Tian, Qinghua; Wang, Lina; Xin, Xiangjun

2018-03-01

Basic configurations of various all-optical clocked flip-flops (FFs) and optical random access memory (RAM) based on the nonlinear polarization rotation (NPR) effect of low-polarization-dependent semiconductor optical amplifiers (SOA) are proposed. As the constituent elements, all-optical logic gates and all-optical SR latches are constructed by taking advantage of the SOA's NPR switch. Different all-optical FFs (AOFFs), including SR-, D-, T-, and JK-types as well as an optical RAM cell were obtained by the combination of the proposed all-optical SR latches and logic gates. The effectiveness of the proposed schemes were verified by simulation results and demonstrated by a D-FF and 1-bit RAM cell experimental system. The proposed all-optical clocked FFs and RAM cell are significant to all-optical signal processing.

Manufacturing plastic injection optical molds

NASA Astrophysics Data System (ADS)

Bourque, David

2008-08-01

ABCO Tool & Die, Inc. is a mold manufacturer specializing in the manufacturing of plastic injection molds for molded optical parts. The purpose of this presentation is to explain the concepts and procedures required to build a mold that produces precision optical parts. Optical molds can produce a variety of molded parts ranging from safety eyewear to sophisticated military lens parts, which must meet precise optical specifications. The manufacturing of these molds begins with the design engineering of precision optical components. The mold design and the related optical inserts are determined based upon the specific optical criteria and optical surface geometry. The mold manufacturing techniques will be based upon the optical surface geometry requirements and specific details. Manufacturing processes used will be specific to prescribed geometrical surface requirements of the molded part. The combined efforts result in a robust optical mold which can produce molded parts that meet the most precise optical specifications.

Holography and optical information processing; Proceedings of the Soviet-Chinese Joint Seminar, Bishkek, Kyrgyzstan, Sept. 21-26, 1991

NASA Astrophysics Data System (ADS)

Mikaelian, Andrei L.

Attention is given to data storage, devices, architectures, and implementations of optical memory and neural networks; holographic optical elements and computer-generated holograms; holographic display and materials; systems, pattern recognition, interferometry, and applications in optical information processing; and special measurements and devices. Topics discussed include optical immersion as a new way to increase information recording density, systems for data reading from optical disks on the basis of diffractive lenses, a new real-time optical associative memory system, an optical pattern recognition system based on a WTA model of neural networks, phase diffraction grating for the integral transforms of coherent light fields, holographic recording with operated sensitivity and stability in chalcogenide glass layers, a compact optical logic processor, a hybrid optical system for computing invariant moments of images, optical fiber holographic inteferometry, and image transmission through random media in single pass via optical phase conjugation.

Novel optoelectronic devices; Proceedings of the Meeting, The Hague, Netherlands, Mar. 31-Apr. 2, 1987

NASA Technical Reports Server (NTRS)

Adams, Michael J. (Editor)

1987-01-01

The present conference on novel optoelectronics discusses topics in the state-of-the-art in this field in the Netherlands, quantum wells, integrated optics, nonlinear optical devices and fiber-optic-based devices, ultrafast optics, and nonlinear optics and optical bistability. Attention is given to the production of fiber-optics for telecommunications by means of PCVD, lifetime broadening in quantum wells, nonlinear multiple quantum well waveguide devices, tunable single-wavelength lasers, an Si integrated waveguiding polarimeter, and an electrooptic light modulator using long-range surface plasmons. Also discussed are backward-wave couplers and reflectors, a wavelength-selective all-fiber switching matrix, the impact of ultrafast optics in high-speed electronics, the physics of low energy optical switching, and all-optical logical elements for optical processing.

Electro-Optic Computing Architectures. Volume I

DTIC Science & Technology

1998-02-01

The objective of the Electro - Optic Computing Architecture (EOCA) program was to develop multi-function electro - optic interfaces and optical...interconnect units to enhance the performance of parallel processor systems and form the building blocks for future electro - optic computing architectures...Specifically, three multi-function interface modules were targeted for development - an Electro - Optic Interface (EOI), an Optical Interconnection Unit (OW

Coherent Beam Combining of Fiber Amplifiers via LOCSET (Postprint)

DTIC Science & Technology

2012-07-10

load on final optics , and atmospheric turbulence compensation [20]. More importantly, tiled array systems are being investigated for extension to...compactness, near diffraction limited beam quality, superior thermal- optical properties, and high optical to optical conversion efficiencies. Despite...including: compactness, near diffraction limited beam quality, superior thermal- optical properties, and high optical to optical conversion efficiencies

Optical domain analog to digital conversion methods and apparatus

DOEpatents

Vawter, Gregory A

2014-05-13

Methods and apparatus for optical analog to digital conversion are disclosed. An optical signal is converted by mapping the optical analog signal onto a wavelength modulated optical beam, passing the mapped beam through interferometers to generate analog bit representation signals, and converting the analog bit representation signals into an optical digital signal. A photodiode receives an optical analog signal, a wavelength modulated laser coupled to the photodiode maps the optical analog signal to a wavelength modulated optical beam, interferometers produce an analog bit representation signal from the mapped wavelength modulated optical beam, and sample and threshold circuits corresponding to the interferometers produce a digital bit signal from the analog bit representation signal.

128×128 three-dimensional MEMS optical switch module with simultaneous optical path connection for optical cross-connect systems.

PubMed

Mizukami, Masato; Yamaguchi, Joji; Nemoto, Naru; Kawajiri, Yuko; Hirata, Hirooki; Uchiyama, Shingo; Makihara, Mitsuhiro; Sakata, Tomomi; Shimoyama, Nobuhiro; Oda, Kazuhiro

2011-07-20

A 128×128 three-dimensional MEMS optical switch module and a switching-control algorithm for high-speed connection and optical power stabilization are described. A prototype switch module enables the simultaneous switching of all optical paths. The insertion loss is less than 4.6 dB and is 2.3 dB on average. The switching time is less than 38 ms and is 8 ms on average. We confirmed that the maximum optical power can be obtained and optical power stabilization control is possible. The results confirm that the module is suitable for practical use in optical cross-connect systems. © 2011 Optical Society of America

Optical and mechanical response of high temperature optical fiber sensors

NASA Technical Reports Server (NTRS)

Sirkis, Jim

1991-01-01

The National Aerospace Plane (NASP) will experience temperatures as high as 2500 F at critical locations in its structure. Optical fiber sensors were proposed as a means of monitoring the temperature in these critical regions by either bonding the optical fiber to, or embedding the optical fiber in, metal matrix composite (MMC) components. Unfortunately, the anticipated NASP temperature ranges exceed the glass transition region of the optical fiber glass. The attempt is made to define the operating temperature range of optical fiber sensors from both optical and mechanical perspectives. A full non-linear optical analysis was performed by modeling the optical response of an isolated sensor cyclically driven through the glass transition region.

Electro-optic crystal mosaics for the generation of terahertz radiation

DOEpatents

Carrig, Timothy J.; Taylor, Antoinette J.; Stewart, Kevin R.

1996-01-01

Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification.

Electro-optic crystal mosaics for the generation of terahertz radiation

DOEpatents

Carrig, T.J.; Taylor, A.J.; Stewart, K.R.

1996-08-06

Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.

Research studies on advanced optical module/head designs for optical devices

NASA Technical Reports Server (NTRS)

Burke, James J.

1991-01-01

A summary is presented of research in optical data storage materials and of research at the center. The first section contains summary reports under the general headings of: (1) Magnetooptic media: modeling, design, fabrication, characterization, and testing; (2) Optical heads: holographic optical elements; and (3) Optical heads: integrated optics. The second section consist of a proposal entitled, Signal Processing Techniques for Optical Data Storage. And section three presents various publications prepared by the center.

RxGen General Optical Model Prescription Generator

NASA Technical Reports Server (NTRS)

Sigrist, Norbert

2012-01-01

RxGen is a prescription generator for JPL's in-house optical modeling software package called MACOS (Modeling and Analysis for Controlled Optical Systems), which is an expert optical analysis software package focusing on modeling optics on dynamic structures, deformable optics, and controlled optics. The objectives of RxGen are to simplify and automate MACOS prescription generations, reducing errors associated with creating such optical prescriptions, and improving user efficiency without requiring MACOS proficiency. RxGen uses MATLAB (a high-level language and interactive environment developed by MathWorks) as the development and deployment platform, but RxGen can easily be ported to another optical modeling/analysis platform. Running RxGen within the modeling environment has the huge benefit that variations in optical models can be made an integral part of the modeling state. For instance, optical prescription parameters determined as external functional dependencies, optical variations by controlling the in-/exclusion of optical components like sub-systems, and/or controlling the state of all components. Combining the mentioned capabilities and flexibilities with RxGen's optical abstraction layer completely eliminates the hindering aspects for requiring proficiency in writing/editing MACOS prescriptions, allowing users to focus on the modeling aspects of optical systems, i.e., increasing productivity and efficiency. RxGen provides significant enhancements to MACOS and delivers a framework for fast prototyping as well as for developing very complex controlled optical systems.

PREFACE: 3rd International Symposium ''Optics and its Applications''

NASA Astrophysics Data System (ADS)

Calvo, M. L.; Dolganova, I. N.; Gevorgyan, N.; Guzman, A.; Papoyan, A.; Sarkisyan, H.; Yurchenko, S.

2016-01-01

The SPIE.FOCUS Armenia: 3rd International Symposium ''Optics and its Applications'' (OPTICS-2015) http://rau.am/optics2015/ was held in Yerevan, Armenia, in the period October 1 - 5, 2015. The symposium was organized by the International Society for Optics and Photonics (SPIE), the Armenian SPIE student chapter with collaboration of the Armenian TC of ICO, the Russian-Armenian University (RAU), the Institute for Physical Research of National Academy of Sciences of Armenia (IPR of NAS), the Greek-Armenian industrial company LT-PYRKAL, and the Yerevan State University (YSU). The Symposium was co-organized by the SPIE & OSA student chapters of BMSTU, the Armenian OSA student chapter, and the SPIE student chapters of Lund University and Wroclaw University of Technology. The symposium OPTICS-2015 was dedicated to the International Year of Light and Light-Based Technologies. OPTICS-2015 was devoted to modern topics and optical technologies such as: optical properties of nanostructures, silicon photonics, quantum optics, singular optics & its applications, laser spectroscopy, strong field optics, biomedical optics, nonlinear & ultrafast optics, photonics & fiber optics, and mathematical methods in optics. OPTICS-2015 was attended by 100 scientists and students representing 17 countries: Armenia, China, Czech Republic, France, Georgia, Germany, India, Iran, Italy, Latvia, Mexico, Poland, Russia, Saudi Arabia, Sweden, Ukraine, and USA. Such a broad international community confirmed the important mission of science to be a uniting force between different countries, religions, and nations. We hope that OPTICS-2015 inspired and motivated students and young scientists to work in optics and in science in general. The present volume of Journal of Physics: Conference Series includes proceedings of the symposium covering various aspects of modern problems in optics. We are grateful to all people who were involved in the organization process. We gratefully acknowledge support from SPIE under the Federation of Optics College and University Students (FOCUS) conference grant, as well as contributions from other organizations: the Abdus Salam International Center for Theoretical Physics (ICTP), the Optical Society (OSA), the Laboratory of Terahertz Technology of Bauman Moscow State Technical University (BMSTU), the RAU, the LT-Pyrkal, the King Abdullah University of Science and Technology (KAUST), IPR of NAS, and Ritea.

High bandwidth electro-optic technology for intersatellite optical communications

NASA Technical Reports Server (NTRS)

Krainak, Michael A.

1992-01-01

The research and development of electronic and electro-optic components for geosynchronous and low earth orbiting satellite optical high bandwidth communications at the NASA-Goddard Space Flight Center is reviewed. Intersatellite optical communications retains a strong reliance on microwave circuit technology in several areas - the microwave to optical interface, the laser transmitter modulation driver and the optical receiver. A microwave to optical interface is described requiring high bandwidth electronic downconverters and demodulators. Electrical bandwidth and current drive requirements for the laser modulation driver for three laser alternatives are discussed. Bandwidth and noise requirements are presented for optical receiver architectures.

Research on Retro-reflecting Modulation in Space Optical Communication System

NASA Astrophysics Data System (ADS)

Zhu, Yifeng; Wang, Guannan

2018-01-01

Retro-reflecting modulation space optical communication is a new type of free space optical communication technology. Unlike traditional free space optical communication system, it applys asymmetric optical systems to reduce the size, weight and power consumption of the system and can effectively solve the limits of traditional free space optical communication system application, so it can achieve the information transmission. This paper introduces the composition and working principle of retro-reflecting modulation optical communication system, analyzes the link budget of this system, reviews the types of optical system and optical modulator, summarizes this technology future research direction and application prospects.

Development of integrated optical tracking sensor by planar optics

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sasagawa, Tomohiro; Nishimae, Junichi; Sato, Yukio

1999-03-01

A compact and light weight optical tracking sensor for a large capacity flexible disk drive is demonstrated. The size of the optical element is no larger than 5.4 mm in length X 3.6 mm in width X 1.2 mm in height and the weight is only 18 mg. The application of the planar optical technique makes it possible to integrate all passive optical elements onto one transparent substrate. These features are useful for high- speed access, easy optical alignment, mass production, and miniaturization. The design and optical characteristics of the optical tracking sensor are described.

Analysis of optical route in a micro high-speed magneto-optic switch

NASA Astrophysics Data System (ADS)

Weng, Zihua; Yang, Guoguang; Huang, Yuanqing; Chen, Zhimin; Zhu, Yun; Wu, Jinming; Lin, Shufen; Mo, Weiping

2005-02-01

A novel micro high-speed 2x2 magneto-optic switch and its optical route, which is used in high-speed all-optical communication network, is designed and analyzed in this paper. The study of micro high-speed magneto-optic switch mainly involves the optical route and high-speed control technique design. The optical route design covers optical route design of polarization in optical switch, the performance analysis and material selection of magneto-optic crystal and magnetic path design in Faraday rotator. The research of high-speed control technique involves the study of nanosecond pulse generator, high-speed magnetic field and its control technique etc. High-speed current transients from nanosecond pulse generator are used to switch the magnetization of the magneto-optic crystal, which propagates a 1550nm optical beam. The optical route design schemes and electronic circuits of high-speed control technique are both simulated on computer and test by the experiments respectively. The experiment results state that the nanosecond pulse generator can output the pulse with rising edge time 3~35ns, voltage amplitude 10~90V and pulse width 10~100ns. Under the control of CPU singlechip, the optical beam can be stably switched and the switching time is less than 1μs currently.

Highly Non-Linear Optical (NLO) organic crystals and films. Electrooptical organic materials

NASA Technical Reports Server (NTRS)

Mcmanus, Samuel P.; Rosenberger, Franz; Matthews, John

1987-01-01

Devices employing nonlinear optics (NLO) hold great promise for important applications in integrated optics, optical information processing and telecommunications. Properly designed organics possess outstanding optical and electrooptical properties which will substantially advance many technologies including electrooptical switching, optical amplification for communications, and parallel processing for hybrid optical computers. A brief comparison of organic and inorganic materials is given.

Optical apparatus for forming correlation spectrometers and optical processors

DOEpatents

Butler, Michael A.; Ricco, Antonio J.; Sinclair, Michael B.; Senturia, Stephen D.

1999-01-01

Optical apparatus for forming correlation spectrometers and optical processors. The optical apparatus comprises one or more diffractive optical elements formed on a substrate for receiving light from a source and processing the incident light. The optical apparatus includes an addressing element for alternately addressing each diffractive optical element thereof to produce for one unit of time a first correlation with the incident light, and to produce for a different unit of time a second correlation with the incident light that is different from the first correlation. In preferred embodiments of the invention, the optical apparatus is in the form of a correlation spectrometer; and in other embodiments, the apparatus is in the form of an optical processor. In some embodiments, the optical apparatus comprises a plurality of diffractive optical elements on a common substrate for forming first and second gratings that alternately intercept the incident light for different units of time. In other embodiments, the optical apparatus includes an electrically-programmable diffraction grating that may be alternately switched between a plurality of grating states thereof for processing the incident light. The optical apparatus may be formed, at least in part, by a micromachining process.

Optical apparatus for forming correlation spectrometers and optical processors

DOEpatents

Butler, M.A.; Ricco, A.J.; Sinclair, M.B.; Senturia, S.D.

1999-05-18

Optical apparatus is disclosed for forming correlation spectrometers and optical processors. The optical apparatus comprises one or more diffractive optical elements formed on a substrate for receiving light from a source and processing the incident light. The optical apparatus includes an addressing element for alternately addressing each diffractive optical element thereof to produce for one unit of time a first correlation with the incident light, and to produce for a different unit of time a second correlation with the incident light that is different from the first correlation. In preferred embodiments of the invention, the optical apparatus is in the form of a correlation spectrometer; and in other embodiments, the apparatus is in the form of an optical processor. In some embodiments, the optical apparatus comprises a plurality of diffractive optical elements on a common substrate for forming first and second gratings that alternately intercept the incident light for different units of time. In other embodiments, the optical apparatus includes an electrically-programmable diffraction grating that may be alternately switched between a plurality of grating states thereof for processing the incident light. The optical apparatus may be formed, at least in part, by a micromachining process. 24 figs.

MSFC Optical Metrology: A National Resource

NASA Technical Reports Server (NTRS)

Burdine, Robert

1998-01-01

A national need exists for Large Diameter Optical Metrology Services. These services include the manufacture, testing, and assurance of precision and control necessary to assure the success of large optical projects. "Best Practices" are often relied on for manufacture and quality controls while optical projects are increasingly more demanding and complex. Marshall Space Flight Center (MSFC) has acquired unique optical measurement, testing and metrology capabilities through active participation in a wide variety of NASA optical programs. An overview of existing optical facilities and metrology capabilities is given with emphasis on use by other optical projects. Cost avoidance and project success is stressed through use of existing MSFC facilities and capabilities for measurement and metrology controls. Current issues in large diameter optical metrology are briefly reviewed. The need for a consistent and long duration Large Diameter Optical Metrology Service Group is presented with emphasis on the establishment of a National Large Diameter Optical Standards Laboratory. Proposals are made to develop MSFC optical standards and metrology capabilities as the primary national standards resource, providing access to MSFC Optical Core Competencies for manufacturers and researchers. Plans are presented for the development of a national lending library of precision optical standards with emphasis on cost avoidance while improving measurement assurance.

Silicon photonics thermal phase shifter with reduced temperature range

DOEpatents

Lentine, Anthony L; Kekatpure, Rohan D; DeRose, Christopher; Davids, Paul; Watts, Michael R

2013-12-17

Optical devices, phased array systems and methods of phase-shifting an input signal are provided. An optical device includes a microresonator and a waveguide for receiving an input optical signal. The waveguide includes a segment coupled to the microresonator with a coupling coefficient such that the waveguide is overcoupled to the microresonator. The microresonator received the input optical signal via the waveguide and phase-shifts the input optical signal to form an output optical signal. The output optical signal is coupled into the waveguide via the microresonator and transmitted by the waveguide. At an operating point of the optical device, the coupling coefficient is selected to reduce a change in an amplitude of the output optical signal and to increase a change in a phase of the output optical signal, relative to the input optical signal.

Optical-microwave interactions in semiconductor devices

NASA Astrophysics Data System (ADS)

Figueroa, L.; Slayman, C.; Yen, H. W.

1980-02-01

GaAs FETs with built-in optical waveguides are being developed. The purpose is to allow optical signals to be coupled into the active region of the devices efficiently. These FETs will be useful for optical mixing, optical injection locking, and optical detection purposes.

Electro-Optic Modulator and Method

DTIC Science & Technology

An optical intensity modulator which uses a Sagnac interferometer having an electro - optic phase modulator therein. An electric modulation signal is...modulating the optical signals by the electrical signal, the electro - optic effect in the modulator phase shifts the optical signals with respect to one another

1984 European Conference on Optics, Optical Systems and Applications, Amsterdam, Netherlands, October 9-12, 1984, Proceedings

NASA Astrophysics Data System (ADS)

Boelger, B.; Ferwerda, H. A.

Various papers on optics, optical systems, and their applications are presented. The general topics addressed include: laser systems, optical and electrooptical materials and devices; novel spectroscopic techniques and applications; inspection, remote sensing, velocimetry, and gauging; optical design and image formation; holography, image processing, and storage; and integrated and fiber optics. Also discussed are: nonlinear optics; nonlinear photorefractive materials; scattering and diffractions applications in materials processing, deposition, and machining; medical and biological applications; and focus on industry.

Board-to-board optical interconnection using novel optical plug and slot

NASA Astrophysics Data System (ADS)

Cho, In K.; Yoon, Keun Byoung; Ahn, Seong H.; Kim, Jin Tae; Lee, Woo Jin; Shin, Kyoung Up; Heo, Young Un; Park, Hyo Hoon

2004-10-01

A novel optical PCB with transmitter/receiver system boards and optical bakcplane was prepared, which is board-to-board interconnection by optical plug and slot. We report an 8Gb/s PRBS NRZ data transmission between transmitter system board and optical backplane embedded multimode polymeric waveguide arrays. The basic concept of ETRI's optical PCB is as follows; 1) Metal optical bench is integrated with optoelectronic devices, driver and receiver circuits, polymeric waveguide and access line PCB module. 2) Multimode polymeric waveguide inside an optical backplane, which is embedded into PCB. 3) Optical slot and plug for high-density(channel pitch : 500um) board-to-board interconnection. The polymeric waveguide technology can be used for transmission of data on transmitter/ receiver system boards and for backplane interconnections. The main components are low-loss tapered polymeric waveguides and a novel optical plug and slot for board-to-board interconnections, respectively. The optical PCB is characteristic of low coupling loss, easy insertion/extraction of the boards and, especially, reliable optical coupling unaffected from external environment after board insertion.

Optical nulling apparatus and method for testing an optical surface

NASA Technical Reports Server (NTRS)

Olczak, Eugene (Inventor); Hannon, John J. (Inventor); Dey, Thomas W. (Inventor); Jensen, Arthur E. (Inventor)

2008-01-01

An optical nulling apparatus for testing an optical surface includes an aspheric mirror having a reflecting surface for imaging light near or onto the optical surface under test, where the aspheric mirror is configured to reduce spherical aberration of the optical surface under test. The apparatus includes a light source for emitting light toward the aspheric mirror, the light source longitudinally aligned with the aspheric mirror and the optical surface under test. The aspheric mirror is disposed between the light source and the optical surface under test, and the emitted light is reflected off the reflecting surface of the aspheric mirror and imaged near or onto the optical surface under test. An optical measuring device is disposed between the light source and the aspheric mirror, where light reflected from the optical surface under test enters the optical measuring device. An imaging mirror is disposed longitudinally between the light source and the aspheric mirror, and the imaging mirror is configured to again reflect light, which is first reflected from the reflecting surface of the aspheric mirror, onto the optical surface under test.

Highlights of the ASPE 2004 Winter Topical Meeting on Free-Form Optics: Design, Fabrication, Metrology, Assembly

NASA Technical Reports Server (NTRS)

Ohl, Raymond G.; Dow, Thomas A.; Sohn, alex

2004-01-01

We present highlights from the American Society for Precision Engineering's 2004 winter topical meeting entitled Free-Form Optics: Design, Fabrication, Metrology, Assembly. We emphasize those papers that are most relevant to astronomical optics. Optical surfaces that transcend the bounds of rotational symmetry have been implemented in novel optical systems with fantastic results since the release of Polaroid's first instant camera. Despite these successes, free-form optics have found only a few niche applications and have yet to enter the mainstream. The purpose of this meeting is to identify the state of the art of free-form optics design, fabrication, metrology and assembly and to identify the technical and logistical challenges that inhibit their widespread use. Issues that will be addressed include: What are free-form optics? How can optical systems be made better with free-form optics? How can designers use free-form optics? How can free-form optics be fabricated? How can they be measured? How are free-form optical systems assembled? Control of multi-axis systems.

Cultivation mode research of practical application talents for optical engineering major

NASA Astrophysics Data System (ADS)

Liu, Zhiying

2017-08-01

The requirements on science and technology graduates are more and higher with modern science progress and society market economy development. Because optical engineering major is with very long practicality, practice should be paid more attention from analysis of optical engineering major and students' foundation. To play role of practice to a large amount, the practice need be systemic and correlation. It should be combination of foundation and profundity. Modern foundation professional knowledge is studied with traditional optical concept and technology at the same time. Systemic regularity and correlation should be embodied in the contents. Start from basic geometrical optics concept, the optical parameter of optical instrument is analyzed, the optical module is built and ray tracing is completed during geometrical optics practice. With foundation of primary aberration calculation, the optical system is further designed and evaluated during optical design practice course. With the optical model and given instrument functions and requirements, the optical-mechanism is matched. The accuracy is calculated, analyzed and distributed in every motion segment. And the mechanism should guarantee the alignment and adjustment. The optical mechanism is designed during the instrument and element design practice. When the optical and mechanism drawings are completed, the system is ready to be fabricated. Students can complete grinding, polishing and coating process by themselves through optical fabricating practice. With the optical and mechanical elements, the system can be assembled and aligned during the thesis practice. With a set of correlated and logical practices, the students can acquire the whole process knowledge about optical instrument. All details are contained in every practice process. These practical experiences provide students working ability. They do not need much adaption anymore when they go to work after graduation. It is favorable to both student talents and employer.

Hybrid RF / Optical Communication Terminal with Spherical Primary Optics for Optical Reception

NASA Technical Reports Server (NTRS)

Charles, Jeffrey R.; Hoppe, Daniel H.; Sehic, Asim

2011-01-01

Future deep space communications are likely to employ not only the existing RF uplink and downlink, but also a high capacity optical downlink. The Jet Propulsion Laboratory (JPL) is currently investigating the benefits of a ground based hybrid RF and deep space optical terminal based on limited modification of existing 34 meter antenna designs. The ideal design would include as large an optical aperture as technically practical and cost effective, cause minimal impact to RF performance, and remain cost effective even when compared to a separate optical terminal of comparable size. Numerous trades and architectures have been considered, including shared RF and optical apertures having aspheric optics and means to separate RF and optical signals, plus, partitioned apertures in which various zones of the primary are dedicated to optical reception. A design based on the latter is emphasized in this paper, employing spherical primary optics and a new version of a "clamshell" corrector that is optimized to fit within the limited space between the antenna sub-reflector and the existing apex structure that supports the subreflector. The mechanical design of the hybrid accommodates multiple spherical primary mirror panels in the central 11 meters of the antenna, and integrates the clamshell corrector and optical receiver modules with antenna hardware using existing attach points to the maximum extent practical. When an optical collection area is implemented on a new antenna, it is possible to design the antenna structure to accommodate the additional weight of optical mirrors providing an equivalent aperture of several meters diameter. The focus of our near term effort is to use optics with the 34 meter DSS-13 antenna at Goldstone to demonstrate spatial optical acquisition and tracking capability using an optical system that is temporarily integrated into the antenna.

Two to the sixth and counting: a lifetime of optical experiences

NASA Astrophysics Data System (ADS)

Mayo, Jim

2014-12-01

This presentation will cover 64 years of experience with telescopes, optical components, optical coatings, large optics, optical fabrication, lasers and related subjects. It will focus on five topic areas paying special attention to critical lessons learned in these areas. Part 1 will cover contributions and inherent value of mentoring in optical and astronomical sciences. This will include specific personal experiences and valuable lessons learned from teachers and mentors going back to the beginning of the space age and the first satellites. It will also cover selected examples from the author's mentoring and community optics and astronomy outreach efforts. Part 2 will delineate the lessons learned from the investigation and independent expert review and assessment of optical damage incidents over a period of five decades. It will also recount frequent optical misconceptions that have negatively impacted efficient system development and implementation over the years and how to avoid them. Part 3 will consist of a short tutorial on the tools, techniques, and the "how and why" of optical inspection. This will be interlinked with the previous optical damage and mistakes topic, where possible. Part 4 will consist of the author's involvement and experiences in optical education with emphasis on the founding and early years of the University of Arizona Optical Sciences Center, now the College of Optical Sciences. Part 5 will cover the enduring issues and challenges for managers, planners and contributing scientists for large optics and telescope projects. This brief overview will follow up and expand upon the author's presentation on this topic at the 1985 "SPIE Optical Fabrication and Testing Workshop: Large Telescope Optics", Albuquerque, NM. Throughout all topic areas presented, the author will stress the lessons learned and the value of these lessons to the planning, management and successful execution of future optics projects and programs.

An Optical Receiver Post Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administrations (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

An Optical Receiver Post-Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

Characterization on Smart Optics Using Ellipsometry

NASA Technical Reports Server (NTRS)

Song, Kyo D.

2002-01-01

Recently, NASA Langley Research Center developed a smart active optical concept to filter narrow band pass or to control optical intensity. To characterize developed smart optics materials, we have measured thickness and reflection properties of the materials using a WVASE32 ellipsometry. This project allowed us to: (1) prepare the smart optical materials for measurement of thickness and optical properties at NASA Langley Research Center; (2) measure thickness and optical properties of the smart optical materials; (3) evaluate the measured properties in terms of applications for narrow band-pass filters. The outcomes of this research provide optical properties and physical properties of the smart optics on a selected spectral range. The applications of this development were used for field-controlled spectral smart filters.

Methods and apparatus for optical switching using electrically movable optical fibers

DOEpatents

Peterson, Kenneth A [Albuquerque, NM

2007-03-13

Methods and apparatuses for electrically controlled optical switches are presented. An electrically controlled optical switch includes a fixture formed using a laminated dielectric material, a first optical fiber having a fixed segment supported by the fixture and a movable segment extending into a cavity, a second optical fiber having a fixed segment supported by the fixture and an extended segment where an optical interconnect may be established between the first optical fiber and the second optical fiber, and a first electrical actuator functionally coupled to the fixture and the first fiber which alters a position of the moveable segment, based upon a control signal, for changing a state of the optical interconnect between one of two states.

Multilayered metal-insulator nanocavities: toward tunable multi-resonance nano-devices for integrated optics

NASA Astrophysics Data System (ADS)

Song, Junyeob; Zhou, Wei

2017-02-01

Plasmonic nanocavities can control light flows and enhance light-mater interactions at subwavelength scale, and thus can potentially be used as nanoscale components in integrated optics systems either for passive optical coupling, or for active optical modulation and emission. In this work, we investigated a new type of multilayered metal-insulator optical nanocavities that can support multiple localized plasmon resonances with ultra-small mode volumes. The total number of resonance peaks and their resonance wavelengths can be freely and accurately controlled by simple geometric design rules. Multi-resonance plasmonic nanocavities can serve as a nanoscale wavelength-multiplexed optical components in integrated optics systems, such as optical couplers, light emitters, nanolasers, optical sensors, and optical modulators.

Fully optical backplane system using novel optical plug and slot

NASA Astrophysics Data System (ADS)

Cho, In-Kui; Ahn, Seung-Ho; Lee, Woo-Jin; Han, Sang-Pil; Kim, Jin-Tae; Choi, Chun-Ki; Shin, Kyung-Up; Yoon, Keun Byoung; Jeong, Myung-Yung; Park, Hyo Hoon

2005-10-01

A fully optical PCB with transmitter/receiver system boards and optical bakcplane was prepared, which is board-to-board interconnection by an optical slot. We report a 10 Gb/s PRBS NRZ data transmission between transmitter system board and optical backplane embedded multimode polymeric waveguide arrays. The basic concept of the optical PCB is as follows; 1) Metal optical bench is integrated with optoelectronic devices, driver and receiver circuits, polymeric waveguide and access line PCB module. 2) Multimode polymeric waveguide inside an optical backplane, which is embedded into PCB, 3) Optical slot and plug for high-density (channel pitch : 500 um) board-to-board interconnection. The polymeric waveguide technology can be used for transmission of data between transmitter/receiver processing boards and backplane boards. The main components are low-loss tapered polymeric waveguides and a novel optical plug and slot for board-to-board interconnections, respectively. The transmitter/receiver processing boards are designed as plug types, and can be easily plugged-in and -out at an optical backplane board. The optical backplane boards are prepared by employing the lamination processes for conventional electrical PCBs. A practical optical backplane system was implemented with two processing boards and an optical backplane. As connection components between the transmitter/receiver processing boards and backplane board, optical slots made of a 90°-bending structure-embedded optical plug was used. A 10 Gb/s data link was successfully demonstrated. The bit error rate (BER) was determined and is 5.6×10 -9(@10Gb/s) and the BER of 8 Gb/s is < 10 -12.

Multi-channel measurement for hetero-core optical fiber sensor by using CMOS camera

NASA Astrophysics Data System (ADS)

Koyama, Yuya; Nishiyama, Michiko; Watanabe, Kazuhiro

2015-07-01

Fiber optic smart structures have been developed over several decades by the recent fiber optic sensor technology. Optical intensity-based sensors, which use LD or LEDs, can be suitable for the monitor system to be simple and cost effective. In this paper, a novel fiber optic smart structure with human-like perception has been demonstrated by using intensity-based hetero-core optical fiber sensors system with the CMOS detector. The optical intensity from the hetero-core optical fiber bend sensor is obtained as luminance spots indicated by the optical power distributions. A number of optical intensity spots are simultaneously readout by taking a picture of luminance pattern. To recognize the state of fiber optic smart structure with the hetero-core optical fibers, the template matching process is employed with Sum of Absolute Differences (SAD). A fiber optic smart glove having five optic fiber nerves have been employed to monitor hand postures. Three kinds of hand postures have been recognized by means of the template matching process. A body posture monitoring has also been developed by placing the wearable hetero-core optical fiber bend sensors on the body segments. In order for the CMOS system to be a human brain-like, the luminescent spots in the obtained picture were arranged to make the pattern corresponding to the position of body segments. As a result, it was successfully demonstrated that the proposed fiber optic smart structure could recognize eight kinds of body postures. The developed system will give a capability of human brain-like processing to the existing fiber optic smart structures.

Development of optical fiber technology in Poland 2015

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.; Wójcik, Waldemar

2015-12-01

The paper is a digest of works presented during the XVIth National Symposium on Optical Fibres and Their Applications. The Symposium is organized since 1976. OFTA 2015 was organized by Optical Fibre Laboratory of the Faculty of Chemistry at University of Maria Curie Skłodowska, and Institute of Electronics and Information Technology of Lublin University of Technology, in Nałęczów on 22-25 September 2015. The meeting has gathered around 120 participants who presented 85 research and technical papers. The Symposium organized every 18 months is a good portrait of optical fibre technology development in Poland at university laboratories, governmental institutes, company R&D laboratories, etc. Topical tracks of the Symposium were: optical and photonic materials, technology of classical, tailored and structural photonic optical fibres, light propagation physics in optical fibres, passive and active optical fibre components, optical fibre sensors, passive and active optical fibre networks, optical fibre amplifiers and lasers, optical fibre network issues: modulation, architectures, economy, etc.

Wide field strip-imaging optical system

NASA Technical Reports Server (NTRS)

Vaughan, Arthur H. (Inventor)

1994-01-01

A strip imaging wide angle optical system is provided. The optical system is provided with a 'virtual' material stop to avoid aberrational effects inherent in wide angle optical systems. The optical system includes a spherical mirror section for receiving light from a 180-degree strip or arc of a target image. Light received by the spherical mirror section is reflected to a frusto-conical mirror section for subsequent rereflection to a row of optical fibers. Each optical fiber transmits a portion of the received light to a detector. The optical system exploits the narrow cone of acceptance associated with optical fibers to substantially eliminate vignetting effects inherent in wide-angle systems. Further, the optical system exploits the narrow cone of acceptance of the optical fibers to substantially limit spherical aberration. The optical system is ideally suited for any application wherein a 180-degree strip image need be detected, and is particularly well adapted for use in hostile environments such as in planetary exploration.

Optical Circuit Switched Protocol

NASA Technical Reports Server (NTRS)

Monacos, Steve P. (Inventor)

2000-01-01

The present invention is a system and method embodied in an optical circuit switched protocol for the transmission of data through a network. The optical circuit switched protocol is an all-optical circuit switched network and includes novel optical switching nodes for transmitting optical data packets within a network. Each optical switching node comprises a detector for receiving the header, header detection logic for translating the header into routing information and eliminating the header, and a controller for receiving the routing information and configuring an all optical path within the node. The all optical path located within the node is solely an optical path without having electronic storage of the data and without having optical delay of the data. Since electronic storage of the header is not necessary and the initial header is eliminated by the first detector of the first switching node. multiple identical headers are sent throughout the network so that subsequent switching nodes can receive and read the header for setting up an optical data path.

Femtosecond Timekeeping: Slip-Free Clockwork for Optical Timescales

NASA Astrophysics Data System (ADS)

Herman, D.; Droste, S.; Baumann, E.; Roslund, J.; Churin, D.; Cingoz, A.; Deschênes, J.-D.; Khader, I. H.; Swann, W. C.; Nelson, C.; Newbury, N. R.; Coddington, I.

2018-04-01

The generation of true optical time standards will require the conversion of the highly stable optical-frequency output of an optical atomic clock to a high-fidelity time output. We demonstrate a comb-based clockwork that phase-coherently integrates ˜7 ×1020 optical cycles of an input optical frequency to create a coherent time output. We verify the underlying stability of the optical timing system by comparing two comb-based clockworks with a common input optical frequency and show <20 fs total time drift over the 37-day measurement period. Both clockworks also generate traditional timing signals including an optical pulse per second and a 10-MHz rf reference. The optical pulse-per-second time outputs remain synchronized to 240 attoseconds (240 as) at 1000 s. The phase-coherent 10-MHz rf outputs are stable to near a part in 1019 . Fault-free timekeeping from an optical clock to femtosecond level over months is an important step in replacing the current microwave time standard by an optical standard.

Resource Letter: LBOT-1: Laser-based optical tweezers

PubMed Central

Lang, Matthew J.; Block, Steven M.

2006-01-01

This Resource Letter provides a guide to the literature on optical tweezers, also known as laser-based, gradient-force optical traps. Journal articles and books are cited for the following main topics: general papers on optical tweezers, trapping instrument design, optical detection methods, optical trapping theory, mechanical measurements, single molecule studies, and sections on biological motors, cellular measurements and additional applications of optical tweezers. PMID:16971965

Resource Letter: LBOT-1: Laser-based optical tweezers.

PubMed

Lang, Matthew J; Block, Steven M

2003-03-01

This Resource Letter provides a guide to the literature on optical tweezers, also known as laser-based, gradient-force optical traps. Journal articles and books are cited for the following main topics: general papers on optical tweezers, trapping instrument design, optical detection methods, optical trapping theory, mechanical measurements, single molecule studies, and sections on biological motors, cellular measurements and additional applications of optical tweezers.

Electro-Optic Computing Architectures: Volume II. Components and System Design and Analysis

DTIC Science & Technology

1998-02-01

The objective of the Electro - Optic Computing Architecture (EOCA) program was to develop multi-function electro - optic interfaces and optical...interconnect units to enhance the performance of parallel processor systems and form the building blocks for future electro - optic computing architectures...Specifically, three multi-function interface modules were targeted for development - an Electro - Optic Interface (EOI), an Optical Interconnection Unit

Method and device for detecting impact events on a security barrier which includes a hollow rebar allowing insertion and removal of an optical fiber

DOEpatents

Pies, Ross E.

2016-03-29

A method and device for the detection of impact events on a security barrier. A hollow rebar is farmed within a security barrier, whereby the hollow rebar is completely surrounded by the security barrier. An optical fiber passes through the interior of the hollow rebar. An optical transmitter and an optical receiver are both optically connected to the optical fiber and connected to optical electronics. The optical electronics are configured to provide notification upon the detection of an impact event at the security barrier based on the detection of disturbances within the optical fiber.

Magneto-optic current sensor

DOEpatents

Lanagan, Michael T.; Valsko-Vlasov, Vitalii K.; Fisher, Brandon L.; Welp, Ulrich

2003-10-07

An optical current transducer configured to sense current in the conductor is disclosed. The optical current transducer includes a light source and a polarizer that generates linearly polarized light received from a the light source. The light is communicated to a magneto-optic garnet that includes, among other elements, bismuth, iron and oxygen and is coupled to the conductor. The magneto-optic garnet is configured to rotate the polarization of the linearly polarized light received from the polarizer. The optical current transducer also includes an analyzer in optical communication with the magneto-optic garnet. The analyzer detects the rotation of the linearly polarized light caused by the magneto-optic garnet.

Optical signal processing

NASA Technical Reports Server (NTRS)

Casasent, D.

1978-01-01

The article discusses several optical configurations used for signal processing. Electronic-to-optical transducers are outlined, noting fixed window transducers and moving window acousto-optic transducers. Folded spectrum techniques are considered, with reference to wideband RF signal analysis, fetal electroencephalogram analysis, engine vibration analysis, signal buried in noise, and spatial filtering. Various methods for radar signal processing are described, such as phased-array antennas, the optical processing of phased-array data, pulsed Doppler and FM radar systems, a multichannel one-dimensional optical correlator, correlations with long coded waveforms, and Doppler signal processing. Means for noncoherent optical signal processing are noted, including an optical correlator for speech recognition and a noncoherent optical correlator.

Optical multi-species gas monitoring sensor and system

NASA Technical Reports Server (NTRS)

Korman, Valentin (Inventor); Polzin, Kurt A. (Inventor)

2012-01-01

The system includes at least one light source generating light energy having a corresponding wavelength. The system's sensor is based on an optical interferometer that receives light energy from each light source. The interferometer includes a free-space optical path disposed in an environment of interest. The system's sensor includes an optical device disposed in the optical path that causes light energy of a first selected wavelength to continue traversing the optical path whereas light energy of at least one second selected wavelength is directed away from the optical path. The interferometer generates an interference between the light energy of the first selected wavelength so-traversing the optical path with the light energy at the corresponding wavelength incident on the optical interferometer. A first optical detector detects the interference. At least one second detector detects the light energy at the at least one second selected wavelength directed away from the optical path.

Method and system for processing optical elements using magnetorheological finishing

DOEpatents

Menapace, Joseph Arthur; Schaffers, Kathleen Irene; Bayramian, Andrew James; Molander, William A

2012-09-18

A method of finishing an optical element includes mounting the optical element in an optical mount having a plurality of fiducials overlapping with the optical element and obtaining a first metrology map for the optical element and the plurality of fiducials. The method also includes obtaining a second metrology map for the optical element without the plurality of fiducials, forming a difference map between the first metrology map and the second metrology map, and aligning the first metrology map and the second metrology map. The method further includes placing mathematical fiducials onto the second metrology map using the difference map to form a third metrology map and associating the third metrology map to the optical element. Moreover, the method includes mounting the optical element in the fixture in an MRF tool, positioning the optical element in the fixture; removing the plurality of fiducials, and finishing the optical element.

Magneto-optical non-reciprocal devices in silicon photonics

PubMed Central

Shoji, Yuya; Mizumoto, Tetsuya

2014-01-01

Silicon waveguide optical non-reciprocal devices based on the magneto-optical effect are reviewed. The non-reciprocal phase shift caused by the first-order magneto-optical effect is effective in realizing optical non-reciprocal devices in silicon waveguide platforms. In a silicon-on-insulator waveguide, the low refractive index of the buried oxide layer enhances the magneto-optical phase shift, which reduces the device footprints. A surface activated direct bonding technique was developed to integrate a magneto-optical garnet crystal on the silicon waveguides. A silicon waveguide optical isolator based on the magneto-optical phase shift was demonstrated with an optical isolation of 30 dB and insertion loss of 13 dB at a wavelength of 1548 nm. Furthermore, a four port optical circulator was demonstrated with maximum isolations of 15.3 and 9.3 dB in cross and bar ports, respectively, at a wavelength of 1531 nm. PMID:27877640

Optical to optical interface device

NASA Technical Reports Server (NTRS)

Oliver, D. S.; Vohl, P.; Nisenson, P.

1972-01-01

The development, fabrication, and testing of a preliminary model of an optical-to-optical (noncoherent-to-coherent) interface device for use in coherent optical parallel processing systems are described. The developed device demonstrates a capability for accepting as an input a scene illuminated by a noncoherent radiation source and providing as an output a coherent light beam spatially modulated to represent the original noncoherent scene. The converter device developed under this contract employs a Pockels readout optical modulator (PROM). This is a photosensitive electro-optic element which can sense and electrostatically store optical images. The stored images can be simultaneously or subsequently readout optically by utilizing the electrostatic storage pattern to control an electro-optic light modulating property of the PROM. The readout process is parallel as no scanning mechanism is required. The PROM provides the functions of optical image sensing, modulation, and storage in a single active material.

Detecting light in whispering-gallery-mode resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor); Mohageg, Makan (Inventor); Le, Thanh M. (Inventor)

2012-01-01

An optical device including a whispering gallery mode (WGM) optical resonator configured to support one or more whispering gallery modes; and a photodetector optically coupled to an exterior surface of the optical resonator to receive evanescent light from the optical resonator to detect light inside the optical resonator.

All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

PubMed Central

Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

2016-01-01

In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

NASA Astrophysics Data System (ADS)

Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

2016-08-01

In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal.

PubMed

Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

2016-08-05

In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature 'prototype' PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

1996-01-01

In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.

Optical properties of armchair (7, 7) single walled carbon nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gharbavi, K.; Badehian, H., E-mail: hojatbadehian@gmail.com

2015-07-15

Full potential linearized augmented plane waves method with the generalized gradient approximation for the exchange-correlation potential was applied to calculate the optical properties of (7, 7) single walled carbon nanotubes. The both x and z directions of the incident photons were applied to estimate optical gaps, dielectric function, electron energy loss spectroscopies, optical conductivity, optical extinction, optical refractive index and optical absorption coefficient. The results predict that dielectric function, ε (ω), is anisotropic since it has higher peaks along z-direction than x-direction. The static optical refractive constant were calculated about 1.4 (z-direction) and 1.1 (x- direction). Moreover, the electron energymore » loss spectroscopy showed a sharp π electron plasmon peaks at about 6 eV and 5 eV for z and x-directions respectively. The calculated reflection spectra show that directions perpendicular to the tube axis have further optical reflection. Moreover, z-direction indicates higher peaks at absorption spectra in low range energies. Totally, increasing the diameter of armchair carbon nanotubes cause the optical band gap, static optical refractive constant and optical reflectivity to decrease. On the other hand, increasing the diameter cause the optical absorption and the optical conductivity to increase. Moreover, the sharp peaks being illustrated at optical spectrum are related to the 1D structure of CNTs which confirm the accuracy of the calculations.« less

Polycrystalline PLZT/ITO Ceramic Electro-Optic Phase Gratings: Electro- Optically Reconfigurable Diffractive Devices for Free-Space and In-Wafer Interconnects

DTIC Science & Technology

1994-09-01

free-space and waveguide interconnects is investigated through the fabrication, testing and modeling of polycrystalline PLZT/ITO ceramic electro - optic phase...only gratings. PLZT Diffraction grating, Electro - optic diffraction grating, Optical switching, Optical interconnects, Reconfigurable interconnect

Precision Cleaning and Protection of Coated Optical Components for NIF Small Optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phelps, Jim

The purpose of this procedure shall be to define the precision cleaning of finished, coated, small optical components for NIF at Lawrence Livermore National Laboratories. The term “small optical components” includes coated optics that are set into simple mounts, as well as coated, un-mounted optics.

Overview of microoptics: Past, present, and future

NASA Technical Reports Server (NTRS)

Veldkamp, Wilfrid B.

1993-01-01

Through advances in semiconductor miniaturization technology, microrelief patterns, with characteristic dimensions as small as the wavelength of light, can now be mass reproduced to form high-quality and low-cost optical components. In a unique example of technology transfer, from electronics to optics, this capability is allowing optics designers to create innovative optical components that promise to solve key problems in optical sensors, optical communication channels, and optical processors.

Optical interconnection and packaging technologies for advanced avionics systems

NASA Astrophysics Data System (ADS)

Schroeder, J. E.; Christian, N. L.; Cotti, B.

1992-09-01

An optical backplane developed to demonstrate the advantages of high-performance optical interconnections and supporting technologies and designed to be compatible with standard avionics racks is described. The hardware demonstrates the three basic components of optical interconnects: optical sources, an optical signal distribution network, and optical receivers. Results from characterization and environmental tests, including a demonstration of the reliable transmission of serial data at a 1 Gb/s, are reported.

Metal-Coated Optical Fibers for High Temperature Applications

NASA Technical Reports Server (NTRS)

Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

1996-01-01

This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

Optical fiber end-facet polymer suspended-mirror devices

NASA Astrophysics Data System (ADS)

Yao, Mian; Wu, Jushuai; Zhang, A. Ping; Tam, Hwa-Yaw; Wai, P. K. A.

2017-04-01

This paper presents a novel optical fiber device based on a polymer suspended mirror on the end facet of an optical fiber. With an own-developed optical 3D micro-printing technology, SU-8 suspended-mirror devices (SMDs) were successfully fabricated on the top of a standard single-mode optical fiber. Optical reflection spectra of the fabricated SU- 8 SMDs were measured and compared with theoretical analysis. The proposed technology paves a way towards 3D microengineering of the small end-facet of optical fibers to develop novel fiber-optic sensors.

Optical design and testing: introduction.

PubMed

Liang, Chao-Wen; Koshel, John; Sasian, Jose; Breault, Robert; Wang, Yongtian; Fang, Yi Chin

2014-10-10

Optical design and testing has numerous applications in industrial, military, consumer, and medical settings. Assembling a complete imaging or nonimage optical system may require the integration of optics, mechatronics, lighting technology, optimization, ray tracing, aberration analysis, image processing, tolerance compensation, and display rendering. This issue features original research ranging from the optical design of image and nonimage optical stimuli for human perception, optics applications, bio-optics applications, 3D display, solar energy system, opto-mechatronics to novel imaging or nonimage modalities in visible and infrared spectral imaging, modulation transfer function measurement, and innovative interferometry.

Realization of arbitrarily long focus-depth optical vortices with spiral area-varying zone plates

NASA Astrophysics Data System (ADS)

Zheng, Chenglong; Zang, Huaping; Du, Yanli; Tian, Yongzhi; Ji, Ziwen; Zhang, Jing; Fan, Quanping; Wang, Chuanke; Cao, Leifeng; Liang, Erjun

2018-05-01

We provide a methodology to realize an optical vortex with arbitrarily long focus-depth. With a technique of varying each zone area of a phase spiral zone plate one can obtain optics capable of generating ultra-long focus-depth optical vortex from a plane wave. The focal property of such optics was analysed using the Fresnel diffraction theory, and an experimental demonstration was performed to verify its effectiveness. Such optics may bring new opportunity and benefits for optical vortex application such as optical manipulation and lithography.

Received optical power calculations for optical communications link performance analysis

NASA Technical Reports Server (NTRS)

Marshall, W. K.; Burk, B. D.

1986-01-01

The factors affecting optical communication link performance differ substantially from those at microwave frequencies, due to the drastically differing technologies, modulation formats, and effects of quantum noise in optical communications. In addition detailed design control table calculations for optical systems are less well developed than corresponding microwave system techniques, reflecting the relatively less mature state of development of optical communications. Described below are detailed calculations of received optical signal and background power in optical communication systems, with emphasis on analytic models for accurately predicting transmitter and receiver system losses.

Fiber optics: A research paper

NASA Technical Reports Server (NTRS)

Drone, Melinda M.

1987-01-01

Some basic aspects concerning fiber optics are examined. Some history leading up to the development of optical fibers which are now used in the transmission of data in many areas of the world is discussed. Basic theory of the operation of fiber optics is discussed along with methods for improving performance of the optical fiber through much research and design. Splices and connectors are compared and short haul and long haul fiber optic networks are discussed. Fiber optics plays many roles in the commercial world. The use of fiber optics for communication applications is emphasized.

Enhancement of the transverse magneto-optical Kerr effect via resonant tunneling in trilayers containing magneto-optical metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Girón-Sedas, J. A.; Centro de Investigación e Innovación en Bioinformática y Fotónica - CIBioFI, AA 25360 Cali; Mejía-Salazar, J. R., E-mail: jrmejia3146@gmail.com

We propose a way to enhance the transverse magneto-optical Kerr effect, by the excitation of resonant tunneling modes, in subwavelength trilayer structures featuring a dielectric slab sandwiched between two magneto-optical metallic layers. Depending on the magneto-optical layer widths, the proposed system may exhibit an extraordinary transverse magneto-optical Kerr effect, which makes it very attractive for the design and engineering of thin-film magneto-optical-based devices for future photonic circuits or fiber optical-communication systems.

Optical computing research

NASA Astrophysics Data System (ADS)

Goodman, Joseph W.

1987-10-01

Work Accomplished: OPTICAL INTERCONNECTIONS - the powerful interconnect abilities of optical beams have led much optimism about the possible roles for optics in solving interconnect problems at various levels of computer architecture. Examined were the powerful requirements of optical interconnects at the gate-to-gate and chip-to-chip levels. OPTICAL NEUTRAL NETWORKS - basic studies of the convergence properties on the Holfield model, based on mathematical approach - graph theory. OPTICS AND ARTIFICIAL INTELLIGENCE - review the field of optical processing and artificial intelligence, with the aim of finding areas that might be particularly attractive for future investigation(s).

Optical XOR gate

DOEpatents

Vawter, G. Allen

2013-11-12

An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Optical NOR gate

DOEpatents

Skogen, Erik J [Albuquerque, NM; Tauke-Pedretti, Anna [Albuquerque, NM

2011-09-06

An optical NOR gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical NOR gate utilizes two digital optical inputs and a continuous light input to provide a NOR function digital optical output. The optical NOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Method and apparatus for use of III-nitride wide bandgap semiconductors in optical communications

DOEpatents

Hui, Rongqing [Lenexa, KS; Jiang, Hong-Xing [Manhattan, KS; Lin, Jing-Yu [Manhattan, KS

2008-03-18

The present disclosure relates to the use of III-nitride wide bandgap semiconductor materials for optical communications. In one embodiment, an optical device includes an optical waveguide device fabricated using a III-nitride semiconductor material. The III-nitride semiconductor material provides for an electrically controllable refractive index. The optical waveguide device provides for high speed optical communications in an infrared wavelength region. In one embodiment, an optical amplifier is provided using optical coatings at the facet ends of a waveguide formed of erbium-doped III-nitride semiconductor materials.

Ultra Compact Optical Pickup with Integrated Optical System

NASA Astrophysics Data System (ADS)

Nakata, Hideki; Nagata, Takayuki; Tomita, Hironori

2006-08-01

Smaller and thinner optical pickups are needed for portable audio-visual (AV) products and notebook personal computers (PCs). We have newly developed an ultra compact recordable optical pickup for Mini Disc (MD) that measures less than 4 mm from the disc surface to the bottom of the optical pickup, making the optical system markedly compact. We have integrated all the optical components into an objective lens actuator moving unit, while fully satisfying recording and playback performance requirements. In this paper, we propose an ultra compact optical pickup applicable to portable MD recorders.

Fiber optic connector

DOEpatents

Rajic, Slobodan; Muhs, Jeffrey D.

1996-01-01

A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled.

A Practical Guide to Experimental Geometrical Optics

NASA Astrophysics Data System (ADS)

Garbovskiy, Yuriy A.; Glushchenko, Anatoliy V.

2017-12-01

Preface; 1. Markets of optical materials, components, accessories, light sources and detectors; 2. Introduction to optical experiments: light producing, light managing, light detection and measuring; 3. Light detectors based on semiconductors: photoresistors, photodiodes in a photo-galvanic regime. Principles of operation and measurements; 4. Linear light detectors based on photodiodes; 5. Basic laws of geometrical optics: experimental verification; 6. Converging and diverging thin lenses; 7. Thick lenses; 8. Lens systems; 9. Simple optical instruments I: the eye and the magnifier, eyepieces and telescopes; 10. Simple optical instruments II: light illuminators and microscope; 11. Spherical mirrors; 12. Introduction to optical aberrations; 13. Elements of optical radiometry; 14. Cylindrical lenses and vials; 15. Methods of geometrical optics to measure refractive index; 16. Dispersion of light and prism spectroscope; 17. Elements of computer aided optical design; Index.

Surface figure control for coated optics

DOEpatents

Ray-Chaudhuri, Avijit K.; Spence, Paul A.; Kanouff, Michael P.

2001-01-01

A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The optic section has an optical section thickness.sup.2 /optical section diameter ratio of between about 5 to 10 mm, and a thickness variation between front and back surfaces of less than about 10%. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

Transforming Mesoscopic (Bio)materials with Holographic Optical Tweezers

NASA Astrophysics Data System (ADS)

Grier, David

2004-03-01

An optical tweezer uses the forces exerted by a strongly focused beam of light to trap and move objects ranging in size from tens of nanometers to tens of micrometers. Since their introduction in 1986, optical tweezers have become a mainstay of research in biology, physical chemistry, and soft condensed matter physics. This talk highlights recent advances made possible by new classes of optical traps created with computer-designed holograms, a technique we call holographic optical trapping. Holographic optical tweezers can trap hundreds of mesoscopic objects simultaneously and move them independently in three dimensions. Arrays of optical traps can be used to continuously sort heterogeneous samples into selected fractions, a process we call optical fractionation. The same holograms can transform optical traps into optical scalpels and scissors that photochemically transform mesoscopic samples with exquisite spatial resolution. They also can impose arbitrary phase profiles onto the trapping beams, thereby creating optical vortices and related optical machines capable of actuating MEMS devices and driving mesoscale pumps and mixers. These new applications for laser light promise to take optical tweezers out of the laboratory and into real-world applications including manufacturing, diagnostics, and even consumer products. The unprecedented access to the mesoscopic world provided by holographic optical tweezers also offers revolutionary new opportunities for fundamental and applied research.

System and method for ultrafast optical signal detecting via a synchronously coupled anamorphic light pulse encoded laterally

DOEpatents

Heebner, John E [Livermore, CA

2010-08-03

In one general embodiment, a method for ultrafast optical signal detecting is provided. In operation, a first optical input signal is propagated through a first wave guiding layer of a waveguide. Additionally, a second optical input signal is propagated through a second wave guiding layer of the waveguide. Furthermore, an optical control signal is applied to a top of the waveguide, the optical control signal being oriented diagonally relative to the top of the waveguide such that the application is used to influence at least a portion of the first optical input signal propagating through the first wave guiding layer of the waveguide. In addition, the first and the second optical input signals output from the waveguide are combined. Further, the combined optical signals output from the waveguide are detected. In another general embodiment, a system for ultrafast optical signal recording is provided comprising a waveguide including a plurality of wave guiding layers, an optical control source positioned to propagate an optical control signal towards the waveguide in a diagonal orientation relative to a top of the waveguide, at least one optical input source positioned to input an optical input signal into at least a first and a second wave guiding layer of the waveguide, and a detector for detecting at least one interference pattern output from the waveguide, where at least one of the interference patterns results from a combination of the optical input signals input into the first and the second wave guiding layer. Furthermore, propagation of the optical control signal is used to influence at least a portion of the optical input signal propagating through the first wave guiding layer of the waveguide.

Defining the uncertainty of electro-optical identification system performance estimates using a 3D optical environment derived from satellite

NASA Astrophysics Data System (ADS)

Ladner, S. D.; Arnone, R.; Casey, B.; Weidemann, A.; Gray, D.; Shulman, I.; Mahoney, K.; Giddings, T.; Shirron, J.

2009-05-01

Current United States Navy Mine-Counter-Measure (MCM) operations primarily use electro-optical identification (EOID) sensors to identify underwater targets after detection via acoustic sensors. These EOID sensors which are based on laser underwater imaging by design work best in "clear" waters and are limited in coastal waters especially with strong optical layers. Optical properties and in particular scattering and absorption play an important role on systems performance. Surface optical properties alone from satellite are not adequate to determine how well a system will perform at depth due to the existence of optical layers. The spatial and temporal characteristics of the 3d optical variability of the coastal waters along with strength and location of subsurface optical layers maximize chances of identifying underwater targets by exploiting optimum sensor deployment. Advanced methods have been developed to fuse the optical measurements from gliders, optical properties from "surface" satellite snapshot and 3-D ocean circulation models to extend the two-dimensional (2-D) surface satellite optical image into a three-dimensional (3-D) optical volume with subsurface optical layers. Modifications were made to an EOID performance model to integrate a 3-D optical volume covering an entire region of interest as input and derive system performance field. These enhancements extend present capability based on glider optics and EOID sensor models to estimate the system's "image quality". This only yields system performance information for a single glider profile location in a very large operational region. Finally, we define the uncertainty of the system performance by coupling the EOID performance model with the 3-D optical volume uncertainties. Knowing the ensemble spread of EOID performance field provides a new and unique capability for tactical decision makers and Navy Operations.

Characterization of transimpedance amplifier as optical to electrical converter on designing optical instrumentation

NASA Astrophysics Data System (ADS)

Hanto, D.; Ula, R. K.

2017-05-01

Optical to electrical converter is the main components for designing of the optical instrumentations. In addition, this component is also used as signal conditioning. This component usually consists of a photo detector and amplifier. In this paper, characteristics of commercial amplifiers from Thorlabs PDA50B-EC has been observed. The experiment was conducted by diode laser with power of -5 dBm and wavelength 1310 nm; the optical attenuator to vary optical power from 0 to 60 dB, optical to electrical converter from Thorlabs Amplifier PDA50B-EC; multimode optical fiber to guide the laser; and digital voltmeter to measure the output of converter. The results of the characterization indicate that each channel amplification has a non-linear correlation between optical and electrical parameter; optical conversion measurement range of 20-23 dB to full scale; and different measurement coverage area. If this converter will be used as a part component of optical instrumentation so it should be adjusted suitably with the optical power source. Then, because of the correlation equation is not linear so calculation to determine the interpretation also should be considered in addition to the transfer function of the optical sensor.

Recent advancements in robotic micro-optical assembly at the Lockheed Martin Optical Payload Center of Excellence

NASA Astrophysics Data System (ADS)

Hwang, David; Larson, Thomas M.

2017-08-01

Lockheed Martin Space Systems Company Optical Payloads Center of Excellence is in process of standing up the Robotic Optical Assembly System (ROAS) capability at Lockheed Martin Coherent Technologies in Colorado. This currently implemented Robotic Optical Assembly has enabled Lockheed Martin to create world-leading, ultra-lowSWAP photonic devices using a closed-loop control robot to precisely position and align micro-optics with a potential fill factor of >25 optics per square inch. This paper will discuss the anticipated applications and optical capability when ROAS is fully operational, as well as challenge the audience to update their "rules of thumb" and best practices when designing low-SWAP optical-mechanical systems that take advantage of Lockheed Martin's ROAS capability. This paper will reveal demonstrated optical pointing and stability performance achievable with ROAS and why we believe these optical specifications are relevant for the majority of anticipated applications. After a high level overview of the ROAS current state, this paper will focus in on recent results of the "Reworkable Micro-Optics Mounting IRAD". Results from this IRAD will correlate to the anticipated optical specifications required for relevant applications.

Optical information-processing systems and architectures II; Proceedings of the Meeting, San Diego, CA, July 9-13, 1990

NASA Astrophysics Data System (ADS)

Javidi, Bahram

The present conference discusses topics in the fields of neural networks, acoustooptic signal processing, pattern recognition, phase-only processing, nonlinear signal processing, image processing, optical computing, and optical information processing. Attention is given to the optical implementation of an inner-product neural associative memory, optoelectronic associative recall via motionless-head/parallel-readout optical disk, a compact real-time acoustooptic image correlator, a multidimensional synthetic estimation filter, and a light-efficient joint transform optical correlator. Also discussed are a high-resolution spatial light modulator, compact real-time interferometric Fourier-transform processors, a fast decorrelation algorithm for permutation arrays, the optical interconnection of optical modules, and carry-free optical binary adders.

Optical systems engineering - A tutorial

NASA Technical Reports Server (NTRS)

Wyman, C. L.

1979-01-01

The paper examines the use of the systems engineering approach in the design of optical systems, noting that the use of such an approach which involves an integrated interdisciplinary approach to the development of systems is most appropriate for optics. It is shown that the high precision character of optics leads to complex and subtle effects on optical system performance, resulting from structural, thermal dynamical, control system, and manufacturing and assembly considerations. Attention is given to communication problems that often occur among users and optical engineers due to the unique factors of optical systems. It is concluded that it is essential that the optics community provide leadership to resolve communication problems and fully formalize the field of optical systems engineering.

Optical application of electrowetting

NASA Astrophysics Data System (ADS)

He, Mei; Peng, Runling; Chen, Jiabi

2017-02-01

Since electrowetting has been proposed, researchers began to apply eletrowetting into different fields, such as lab-on-chip systems, display technologies, printings and optics etc. This paper mainly introduced structure, theory and application of optical devices based on electrowetting. The optical devices include liquid optical prism, liquid optical lens and display. The paper introduced their principle, specific application and many advantages in optical applications. When they are applied to optical system, production and experiment, they can reduce mechanical moving parts, simplify the structure, operate easily, decrease manufacturing cost and energy consumption, improve working efficiency, and so on. We learn and research them in detail that will contribute to research and develop optical eletrowetting in the future.

Optical probe

DOEpatents

Hencken, Kenneth; Flower, William L.

1999-01-01

A compact optical probe is disclosed particularly useful for analysis of emissions in industrial environments. The instant invention provides a geometry for optically-based measurements that allows all optical components (source, detector, rely optics, etc.) to be located in proximity to one another. The geometry of the probe disclosed herein provides a means for making optical measurements in environments where it is difficult and/or expensive to gain access to the vicinity of a flow stream to be measured. Significantly, the lens geometry of the optical probe allows the analysis location within a flow stream being monitored to be moved while maintaining optical alignment of all components even when the optical probe is focused on a plurality of different analysis points within the flow stream.

Optical Sensors Using Stimulated Brillouin Scattering

NASA Technical Reports Server (NTRS)

Christensen, Caleb A (Inventor); Zavriyev, Anton (Inventor)

2017-01-01

A method for enhancing a sensitivity of an optical sensor having an optical cavity counter-propagates beams of pump light within the optical cavity to produce scattered light based on Stimulated Brillouin Scattering (SBS). The properties of the pump light are selected to generate fast-light conditions for the scattered light, such that the scattered light includes counter-propagating beams of fast light. The method prevents the pump light from resonating within the optical cavity, while allowing the scattered light to resonate within the optical cavity. At least portions of the scattered light are interfered outside of the optical cavity to produce a beat note for a measurement of the optical sensor. The disclosed method is particularly applicable to optical gyroscopes.

Silicon optical modulators for optical digital and analog communications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Lin; Ding, Jianfeng; Zhang, Lei; Shao, Sizu

2017-02-01

Silicon photonics is considered as a promising technology to overcome the difficulties of the existing digital and analog optical communication systems, such as low integration, high cost, and high power consumption. Silicon optical modulator, as a component to transfer data from electronic domain to optical one, has attracted extensive attentions in the past decade. In this paper, we review the statuses of the silicon optical modulators for digital and analog optical communications and introduce our efforts on these topics. We analyze the relationship between the performance and the structural parameters of the silicon optical modulator and present how to optimize its performance including electro-optical bandwidth, modulation efficiency, optical bandwidth and insertion loss. The fabricated silicon optical modulator has an electro-optical bandwidth of 30 GHz. Its extinction ratios are 14.0 dB, 11.2 dB and 9.0 dB at the speeds of 40 Gbps, 50 Gbps and 64 Gbps for OOK modulation. The high extinction ratio of the silicon optical modulator at the high speed makes it very appropriate for the application of optical coherent modulation, such as QPSK and 16-QAM. The fabricated silicon optical modulator also can be utilized for analog optical communication. With respect to a noise floor of -165 dBc, the dynamic ranges for the second-order harmonic and the third-order intermodulation distortion are 90.8 dB and 110.5 dB respectively. By adopting a differential driving structure, the dynamic range for the second-order harmonic can be further improved to 100.0 dB while the third-order intermodulation distortion remains the same level.

Optical pumping in a whispering mode optical waveguide

DOEpatents

Kurnit, Norman A.

1984-01-01

A device and method for optical pumping in a whispering mode optical waveguide. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction pathlengths which are achieved in a small volume.

Fiber distributed feedback laser

NASA Technical Reports Server (NTRS)

Elachi, C.; Evans, G. A.; Yeh, C. (Inventor)

1976-01-01

Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs.

Integrated optics technology study

NASA Technical Reports Server (NTRS)

Chen, B.; Findakly, T.; Innarella, R.

1982-01-01

The status and near term potential of materials and processes available for the fabrication of single mode integrated electro-optical components are discussed. Issues discussed are host material and orientation, waveguide formation, optical loss mechanisms, wavelength selection, polarization effects and control, laser to integrated optics coupling fiber optic waveguides to integrated optics coupling, sources, and detectors. Recommendations of the best materials, technology, and processes for fabrication of integrated optical components for communications and fiber gyro applications are given.

Improved Electro-Optical Switches

NASA Technical Reports Server (NTRS)

Nelson, Bruce N.; Cooper, Ronald F.

1994-01-01

Improved single-pole, double-throw electro-optical switches operate in switching times less than microsecond developed for applications as optical communication systems and networks of optical sensors. Contain no moving parts. In comparison with some prior electro-optical switches, these are simpler and operate with smaller optical losses. Beam of light switched from one output path to other by applying, to electro-optical crystal, voltage causing polarization of beam of light to change from vertical to horizontal.

New Light Sources and Concepts for Electro-Optic Sampling

DTIC Science & Technology

1994-03-01

Research to improve electro - optic sampling led to the development of several high performance optical phase modulators. These phase modulators serve...method of optical pulse shape measurement was demonstrated with 3 ps time resolution, excellent power sensitivity and relative system simplicity. These experiments have opened up the field of temporal optics. Electro - optic sampling.

Center for Adaptive Optics | Home

Science.gov Websites

Center for Adaptive Optics A University of California Science and Technology Center Adaptive distortions in optical systems ... Announcements: The CfAO Summer School on Adaptive Optics 2018 will be held mission of the UC Center for Adaptive Optics is to develop, apply, and disseminate adaptive optics science

Submillisecond Optical Knife-Edge Testing

NASA Technical Reports Server (NTRS)

Thurlow, P.

1983-01-01

Fast computer-controlled sampling of optical knife-edge response (KER) signal increases accuracy of optical system aberration measurement. Submicrosecond-response detectors in optical focal plane convert optical signals to electrical signals converted to digital data, sampled and feed into computer for storage and subsequent analysis. Optical data are virtually free of effects of index-of-refraction gradients.

Development of optical packet and circuit integrated ring network testbed.

PubMed

Furukawa, Hideaki; Harai, Hiroaki; Miyazawa, Takaya; Shinada, Satoshi; Kawasaki, Wataru; Wada, Naoya

2011-12-12

We developed novel integrated optical packet and circuit switch-node equipment. Compared with our previous equipment, a polarization-independent 4 × 4 semiconductor optical amplifier switch subsystem, gain-controlled optical amplifiers, and one 100 Gbps optical packet transponder and seven 10 Gbps optical path transponders with 10 Gigabit Ethernet (10GbE) client-interfaces were newly installed in the present system. The switch and amplifiers can provide more stable operation without equipment adjustments for the frequent polarization-rotations and dynamic packet-rate changes of optical packets. We constructed an optical packet and circuit integrated ring network testbed consisting of two switch nodes for accelerating network development, and we demonstrated 66 km fiber transmission and switching operation of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10GbE frames. Error-free (frame error rate < 1×10(-4)) operation was achieved with optical packets of various packet lengths and packet rates, and stable operation of the network testbed was confirmed. In addition, 4K uncompressed video streaming over OPS links was successfully demonstrated. © 2011 Optical Society of America

Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

NASA Astrophysics Data System (ADS)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

2016-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

Low jitter RF distribution system

DOEpatents

Wilcox, Russell; Doolittle, Lawrence; Huang, Gang

2012-09-18

A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal. An rf phase detect and correct signal circuit outputs a signal corresponding to a phase stabilized rf signal based on the data signal and the frequency received from the receiver box.

Studies in optical parallel processing. [All optical and electro-optic approaches

NASA Technical Reports Server (NTRS)

Lee, S. H.

1978-01-01

Threshold and A/D devices for converting a gray scale image into a binary one were investigated for all-optical and opto-electronic approaches to parallel processing. Integrated optical logic circuits (IOC) and optical parallel logic devices (OPA) were studied as an approach to processing optical binary signals. In the IOC logic scheme, a single row of an optical image is coupled into the IOC substrate at a time through an array of optical fibers. Parallel processing is carried out out, on each image element of these rows, in the IOC substrate and the resulting output exits via a second array of optical fibers. The OPAL system for parallel processing which uses a Fabry-Perot interferometer for image thresholding and analog-to-digital conversion, achieves a higher degree of parallel processing than is possible with IOC.

Optical Computers and Space Technology

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin A.; Frazier, Donald O.; Penn, Benjamin; Paley, Mark S.; Witherow, William K.; Banks, Curtis; Hicks, Rosilen; Shields, Angela

1995-01-01

The rapidly increasing demand for greater speed and efficiency on the information superhighway requires significant improvements over conventional electronic logic circuits. Optical interconnections and optical integrated circuits are strong candidates to provide the way out of the extreme limitations imposed on the growth of speed and complexity of nowadays computations by the conventional electronic logic circuits. The new optical technology has increased the demand for high quality optical materials. NASA's recent involvement in processing optical materials in space has demonstrated that a new and unique class of high quality optical materials are processible in a microgravity environment. Microgravity processing can induce improved orders in these materials and could have a significant impact on the development of optical computers. We will discuss NASA's role in processing these materials and report on some of the associated nonlinear optical properties which are quite useful for optical computers technology.

Fiber optic multiplex optical transmission system

NASA Technical Reports Server (NTRS)

Bell, C. H. (Inventor)

1977-01-01

A multiplex optical transmission system which minimizes external interference while simultaneously receiving and transmitting video, digital data, and audio signals is described. Signals are received into subgroup mixers for blocking into respective frequency ranges. The outputs of these mixers are in turn fed to a master mixer which produces a composite electrical signal. An optical transmitter connected to the master mixer converts the composite signal into an optical signal and transmits it over a fiber optic cable to an optical receiver which receives the signal and converts it back to a composite electrical signal. A de-multiplexer is coupled to the output of the receiver for separating the composite signal back into composite video, digital data, and audio signals. A programmable optic patch board is interposed in the fiber optic cables for selectively connecting the optical signals to various receivers and transmitters.

Time-resolved analysis of nonlinear optical limiting for laser synthesized carbon nanoparticles

NASA Astrophysics Data System (ADS)

Chen, G. X.; Hong, M. H.

2010-11-01

Nonlinear optical limiting materials have attracted much research interest in recent years. Carbon nanoparticles suspended in liquids show a strong nonlinear optical limiting function. It is important to investigate the nonlinear optical limiting process of carbon nanoparticles for further improving their nonlinear optical limiting performance. In this study, carbon nanoparticles were prepared by laser ablation of a carbon target in tetrahydrofuran (THF). Optical limiting properties of the samples were studied with 532-nm laser light, which is in the most sensitive wavelength band for human eyes. The shape of the laser pulse plays an important role for initializing the nonlinear optical limiting effect. Time-resolved analysis of laser pulses discovered 3 fluence stages of optical limiting. Theoretical simulation indicates that the optical limiting is initialized by a near-field optical enhancement effect.

Vertically-tapered optical waveguide and optical spot transformer formed therefrom

DOEpatents

Bakke, Thor; Sullivan, Charles T.

2004-07-27

An optical waveguide is disclosed in which a section of the waveguide core is vertically tapered during formation by spin coating by controlling the width of an underlying mesa structure. The optical waveguide can be formed from spin-coatable materials such as polymers, sol-gels and spin-on glasses. The vertically-tapered waveguide section can be used to provide a vertical expansion of an optical mode of light within the optical waveguide. A laterally-tapered section can be added adjacent to the vertically-tapered section to provide for a lateral expansion of the optical mode, thereby forming an optical spot-size transformer for efficient coupling of light between the optical waveguide and a single-mode optical fiber. Such a spot-size transformer can also be added to a III-V semiconductor device by post processing.

Optical data transmission technology for fixed and drag-on STS payloads umbilicals. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

St.denis, R. W.

1981-01-01

The feasibility of using optical data handling methods to transmit payload checkout and telemetry is discussed. Optical communications are superior to conventional communication systems for the following reasons: high data capacity optical channels; small and light weight optical cables; and optical signal immunity to electromagnetic interference. Task number one analyzed the ground checkout data requirements that may be expected from the payload community. Task number two selected the optical approach based on the interface requirements, the location of the interface, the amount of time required to reconfigure hardware, and the method of transporting the optical signal. Task number three surveyed and selected optical components for the two payload data link. Task number four makes a qualitative comparison of the conventional electrical communication system and the proposed optical communication system.

A method which can enhance the optical-centering accuracy

NASA Astrophysics Data System (ADS)

Zhang, Xue-min; Zhang, Xue-jun; Dai, Yi-dan; Yu, Tao; Duan, Jia-you; Li, Hua

2014-09-01

Optical alignment machining is an effective method to ensure the co-axiality of optical system. The co-axiality accuracy is determined by optical-centering accuracy of single optical unit, which is determined by the rotating accuracy of lathe and the optical-centering judgment accuracy. When the rotating accuracy of 0.2um can be achieved, the leading error can be ignored. An axis-determination tool which is based on the principle of auto-collimation can be used to determine the only position of centerscope is designed. The only position is the position where the optical axis of centerscope is coincided with the rotating axis of the lathe. Also a new optical-centering judgment method is presented. A system which includes the axis-determination tool and the new optical-centering judgment method can enhance the optical-centering accuracy to 0.003mm.

Mini-lidar sensor for the remote stand-off sensing of chemical/biological substances and method for sensing same

DOEpatents

Ray, Mark D.; Sedlacek, Arthur J.

2003-08-19

A method and apparatus for remote, stand-off, and high efficiency spectroscopic detection of biological and chemical substances. The apparatus including an optical beam transmitter which transmits a beam having an axis of transmission to a target, the beam comprising at least a laser emission. An optical detector having an optical detection path to the target is provided for gathering optical information. The optical detection path has an axis of optical detection. A beam alignment device fixes the transmitter proximal to the detector and directs the beam to the target along the optical detection path such that the axis of transmission is within the optical detection path. Optical information gathered by the optical detector is analyzed by an analyzer which is operatively connected to the detector.

High pulse rate high resolution optical radar system

NASA Technical Reports Server (NTRS)

Goss, W. C.; Burns, R. H.; Chi, K. (Inventor)

1973-01-01

The system is composed of an optical cavity with a laser and a mode locking means to build up an optical pulse. An optical switch is also provided within the cavity to convert the polarization of the optical pulse generated within the cavity. The optical switch comprises an electro-optical crystal driven by a time delayed driver circuit which is triggered by a coincident signal made from an optical pulse signal and a gating pulse signal. The converted optical pulse strikes a polarization sensitive prism and is deflected out of the cavity toward the pending target in the form of a pulse containing most of the optical energy generated by the laser in the pulse build-up period. After striking the target, the reflected energy is picked up by a transceiver with the total travel time of the pulse being recorded.

On-chip broadband silicon thermo-optic 2☓2 four-mode optical switch for optical space and local mode switching.

PubMed

Zhou, Ting; Jia, Hao; Ding, Jianfeng; Zhang, Lei; Fu, Xin; Yang, Lin

2018-04-02

We present a silicon thermo-optic 2☓2 four-mode optical switch optimized for optical space switching plus local optical mode switching. Four asymmetric directional couplers are utilized for mode multiplexing and de-multiplexing. Sixteen 2☓2 single-mode optical switches based on balanced thermally tunable Mach-Zehnder interferometers are exploited for switching function. The measured insertion losses are 8.0~12.2 dB and the optical signal-to-noise ratios are larger than 11.2 dB in the wavelength range of 1525~1565 nm. The optical links in "all-bar" and "all-cross" states exhibit less than 2.0 dB and 1.4 dB power penalties respectively below 10 -9 bit error rates for 40 Gbps data transmission.

Optical design of an athermalised dual field of view step zoom optical system in MWIR

NASA Astrophysics Data System (ADS)

Kucukcelebi, Doruk

2017-08-01

In this paper, the optical design of an athermalised dual field of view step zoom optical system in MWIR (3.7μm - 4.8μm) is described. The dual field of view infrared optical system is designed based on the principle of passive athermalization method not only to achieve athermal optical system but also to keep the high image quality within the working temperature between -40°C and +60°C. The infrared optical system used in this study had a 320 pixel x 256 pixel resolution, 20μm pixel pitch size cooled MWIR focal plane array detector. In this study, the step zoom mechanism, which has the axial motion due to consisting of a lens group, is considered to simplify mechanical structure. The optical design was based on moving a single lens along the optical axis for changing the optical system's field of view not only to reduce the number of moving parts but also to athermalize for the optical system. The optical design began with an optimization process using paraxial optics when first-order optics parameters are determined. During the optimization process, in order to reduce aberrations, such as coma, astigmatism, spherical and chromatic aberrations, aspherical surfaces were used. As a result, athermalised dual field of view step zoom optical design is proposed and the performance of the design using proposed method was verified by providing the focus shifts, spot diagrams and MTF analyzes' plots.

Nonlinear Optics and Applications

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

2007-01-01

Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

Perspective and potential of smart optical materials

NASA Astrophysics Data System (ADS)

Choi, Sang H.; Duzik, Adam J.; Kim, Hyun-Jung; Park, Yeonjoon; Kim, Jaehwan; Ko, Hyun-U.; Kim, Hyun-Chan; Yun, Sungryul; Kyung, Ki-Uk

2017-09-01

The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from micro-scale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro convex lens are reviewed, along with the newly discovered pseudo-focal point not predicted with conventional optics modeling. Micron-sized solid state beam scanner chips for laser waveguides are reviewed as well.

A modular optical sensor

NASA Astrophysics Data System (ADS)

Conklin, John Albert

This dissertation presents the design of a modular, fiber-optic sensor and the results obtained from testing the modular sensor. The modular fiber-optic sensor is constructed in such manner that the sensor diaphragm can be replaced with different configurations to detect numerous physical phenomena. Additionally, different fiber-optic detection systems can be attached to the sensor. Initially, the modular sensor was developed to be used by university of students to investigate realistic optical sensors and detection systems to prepare for advance studies of micro-optical mechanical systems (MOMS). The design accomplishes this by doing two things. First, the design significantly lowers the costs associated with studying optical sensors by modularizing the sensor design. Second, the sensor broadens the number of physical phenomena that students can apply optical sensing techniques to in a fiber optics sensor course. The dissertation is divided into seven chapters covering the historical development of fiber-optic sensors, a theoretical overview of fiber-optic sensors, the design, fabrication, and the testing of the modular sensor developed in the course of this work. Chapter 1 discusses, in detail, how this dissertation is organized and states the purpose of the dissertation. Chapter 2 presents an historical overview of the development of optical fibers, optical pressure sensors, and fibers, optical pressure sensors, and optical microphones. Chapter 3 reviews the theory of multi-fiber optic detection systems, optical microphones, and pressure sensors. Chapter 4 presents the design details of the modular, optical sensor. Chapter 5 delves into how the modular sensor is fabricated and how the detection systems are constructed. Chapter 6 presents the data collected from the microphone and pressure sensor configurations of the modular sensor. Finally, Chapter 7 discusses the data collected and draws conclusions about the design based on the data collected. Chapter 7 also presents future work needed to expand the functionality and utility of the modular sensor.

All optical logic for optical pattern recognition and networking applications

NASA Astrophysics Data System (ADS)

Khoury, Jed

2017-05-01

In this paper, we propose architectures for the implementation 16 Boolean optical gates from two inputs using externally pumped phase- conjugate Michelson interferometer. Depending on the gate to be implemented, some require single stage interferometer and others require two stages interferometer. The proposed optical gates can be used in several applications in optical networks including, but not limited to, all-optical packet routers switching, and all-optical error detection. The optical logic gates can also be used in recognition of noiseless rotation and scale invariant objects such as finger prints for home land security applications.

Fiber optic connector

DOEpatents

Rajic, S.; Muhs, J.D.

1996-10-22

A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded are disclosed. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled. 3 figs.

Optimization of x-ray capillary optics for mammography

NASA Astrophysics Data System (ADS)

Ross, Richard E.; Bradford, Carla D.; Peppler, Walter W.

2002-05-01

The purpose of this study is to develop a full-field digital mammography system utilizing capillary optics. Specific aims are to identify optic properties that affect image quality and to optimize those properties in the design of a multi-element capillary array. It has been shown that polycapillary optics significantly improve mammographic image quality through increased resolution and reduced x-ray scatter. For practical clinical application much larger multi-element optics will be required. This study quantified the contributing factors to the multi-element optic MTF and investigated methods to determine optimal parameters for a practical design. Individual and a prototype multi-element array of linearly tapered optics with a common focal point were investigated. A conventional (MO/MO) mammography tube and computed radiography system were used. The system and optic MTF were measured using the angled slit method with a slit camera (10 micron slit). MTF measurements were performed with both stationary and scanned optics. Contributions to MTF included: distortion within individual optics, misalignment between optics, capillary channel size, and vibration. Measurement techniques used to identify and quantify the contributions to optic MTF included a phantom chosen specifically for polycapillary optics. This phantom provided a method for assessing the coherence among capillaries within an optic as well as the relative alignment of the optics within the array. In addition, modifications to the scanning procedure allowed for the isolation and quantification of several contributors to the system MTF. Specifically, measurements were made using a stationary optic, a scanning optic, and an optic placed at multiple locations within the imaged field of view. These techniques yielded the optic MTF, the degradation of MTF due to loss of coherence within the optic, and the degradation of MTF due to vibration of the scanning mechanism. Distortion within individual optics was, typically, quite small. However, MTF degradation resulting from twist was significant in some optics. MTF degradation due to misalignment was relatively large in the prototype triad. Modeling found that misalignment up to 50 microns reduced MTF by less than 10 percent up to 3 cycles/mm. Channel diameters of 52 microns and 85 microns reduced MTF by 9 percent to 20 percent at 5 cycles/mm and provided an optimal tradeoff between transmission and MTF. Vibration was identified as a significant degradation to MTF but can easily reduced with simple modifications. In spite of some reduced optic MTF values, system MTF has always been significantly improved - in some cases almost by the magnification ratio. These results allow for accurate modeling of optic performance and optimization of design parameters. This study demonstrates that a multi-element array can be produced with nearly optimal properties. A large area array suitable for clinical trial is feasible and is the next step in this program.

A novel optical system design of light field camera

NASA Astrophysics Data System (ADS)

Wang, Ye; Li, Wenhua; Hao, Chenyang

2016-01-01

The structure of main lens - Micro Lens Array (MLA) - imaging sensor is usually adopted in optical system of light field camera, and the MLA is the most important part in the optical system, which has the function of collecting and recording the amplitude and phase information of the field light. In this paper, a novel optical system structure is proposed. The novel optical system is based on the 4f optical structure, and the micro-aperture array (MAA) is used to instead of the MLA for realizing the information acquisition of the 4D light field. We analyze the principle that the novel optical system could realize the information acquisition of the light field. At the same time, a simple MAA, line grating optical system, is designed by ZEMAX software in this paper. The novel optical system is simulated by a line grating optical system, and multiple images are obtained in the image plane. The imaging quality of the novel optical system is analyzed.

Wide-angle imaging system with fiberoptic components providing angle-dependent virtual material stops

NASA Technical Reports Server (NTRS)

Vaughan, Arthur H. (Inventor)

1993-01-01

A strip imaging wide angle optical system is provided. The optical system is provided with a 'virtual' material stop to avoid aberrational effects inherent in wide angle optical systems. The optical system includes a spherical mirror section for receiving light from a 180 deg strip or arc of a target image. Light received by the spherical mirror section is reflected to a frustoconical mirror section for subsequent rereflection to a row of optical fibers. Each optical fiber transmits a portion of the received light to a detector. The optical system exploits the narrow cone of acceptance associated with optical fibers to substantially eliminate vignetting effects inherent in wide angle systems. Further, the optical system exploits the narrow cone of acceptance of the optical fibers to substantially limit spherical aberration. The optical system is ideally suited for any application wherein a 180 deg strip image need be detected, and is particularly well adapted for use in hostile environments such as in planetary exploration.

Pedestal substrate for coated optics

DOEpatents

Hale, Layton C.; Malsbury, Terry N.; Patterson, Steven R.

2001-01-01

A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

Simple online recognition of optical data strings based on conservative optical logic

NASA Astrophysics Data System (ADS)

Caulfield, H. John; Shamir, Joseph; Zavalin, Andrey I.; Silberman, Enrique; Qian, Lei; Vikram, Chandra S.

2006-06-01

Optical packet switching relies on the ability of a system to recognize header information on an optical signal. Unless the headers are very short with large Hamming distances, optical correlation fails and optical logic becomes attractive because it can handle long headers with Hamming distances as low as 1. Unfortunately, the only optical logic gates fast enough to keep up with current communication speeds involve semiconductor optical amplifiers and do not lend themselves to the incorporation of large numbers of elements for header recognition and would consume a lot of power as well. The ideal system would operate at any bandwidth with no power consumption. We describe how to design and build such a system by using passive optical logic. This too leads to practical problems that we discuss. We show theoretically various ways to use optical interferometric logic for reliable recognition of long data streams such as headers in optical communication. In addition, we demonstrate one particularly simple experimental approach using interferometric coinc gates.

All-optical retro-modulation for free-space optical communication.

PubMed

Born, Brandon; Hristovski, Ilija R; Geoffroy-Gagnon, Simon; Holzman, Jonathan F

2018-02-19

This work presents device and system architectures for free-space optical and optical wireless communication at high data rates over multidirectional links. This is particularly important for all-optical networks, with high data rates, low latencies, and network protocol transparency, and for asymmetrical networks, with multidirectional links from one transceiver to multiple distributed transceivers. These two goals can be met by implementing a passive uplink via all-optical retro-modulation (AORM), which harnesses the optical power from an active downlink to form a passive uplink through retroreflection. The retroreflected optical power is modulated all-optically to ideally achieve terabit-per-second data rates. The proposed AORM architecture, for passive uplinks, uses high-refractive-index S-LAH79 hemispheres to realize effective retroreflection and an interior semiconductor thin film of CuO nanocrystals to realize ultrafast all-optical modulation on a timescale of approximately 770 fs. The AORM architecture is fabricated and tested, and ultimately shown to be capable of enabling multidirectional free-space optical communication with terabit-per-second aggregate data rates.

OAM-labeled free-space optical flow routing.

PubMed

Gao, Shecheng; Lei, Ting; Li, Yangjin; Yuan, Yangsheng; Xie, Zhenwei; Li, Zhaohui; Yuan, Xiaocong

2016-09-19

Space-division multiplexing allows unprecedented scaling of bandwidth density for optical communication. Routing spatial channels among transmission ports is critical for future scalable optical network, however, there is still no characteristic parameter to label the overlapped optical carriers. Here we propose a free-space optical flow routing (OFR) scheme by using optical orbital angular moment (OAM) states to label optical flows and simultaneously steer each flow according to their OAM states. With an OAM multiplexer and a reconfigurable OAM demultiplexer, massive individual optical flows can be routed to the demanded optical ports. In the routing process, the OAM beams act as data carriers at the same time their topological charges act as each carrier's labels. Using this scheme, we experimentally demonstrate switching, multicasting and filtering network functions by simultaneously steer 10 input optical flows on demand to 10 output ports. The demonstration of data-carrying OFR with nonreturn-to-zero signals shows that this process enables synchronous processing of massive spatial channels and flexible optical network.

High-stability 48-core bendable and movable optical cable for FAST telescope optical transmission system

NASA Astrophysics Data System (ADS)

Liu, Hongfei; Pan, Gaofeng; Lin, Zhong; Liu, Cheng; Zhu, Wenbai; Nan, Rendong; Li, Chunsheng; Gao, Guanjun; Luo, Wenyong; Jin, Chengjin; Song, Jinyou

2017-11-01

The construction of FAST telescope was completed in Guizhou province of China in September 2016, and a kind of novel high-stability 48-core bendable and movable optical cable was developed and applied in analog data optical transmission system of FAST. Novel structure and selective material of this optical cable ensure high stability of optical power in the process of cables round-trip motion when telescope is tracking a radio source. The 105 times bend and stretch accelerated experiment for this optical cable was implemented, and real-time optical and RF signal power fluctuation were measured. The physical structure of optical cables after 105 times round-trip motion is in good condition; the real-time optical power attenuation fluctuation is smaller than 0.044 dB; the real-time RF power fluctuation is smaller than 0.12 dB. The optical cable developed in this letter meets the requirement of FAST and has been applied in FAST telescope.

Integrated design course of applied optics focusing on operating and maintaining abilities

NASA Astrophysics Data System (ADS)

Xu, Zhongjie; Ning, Yu; Jiang, Tian; Cheng, Xiangai

2017-08-01

The abilities of operating and maintaining optical instruments are crucial in modern society. Besides the basic knowledge in optics, the optics courses in the National University of Defense Technology also focus on the training on handling typical optical equipment. As the link between classroom courses on applied optics and the field trips, the integrated design course of applied optics aims to give the students a better understanding on several instantly used optical equipment, such as hand-held telescope and periscope, etc. The basic concepts of optical system design are also emphasized as well. The course is arranged rightly after the classroom course of applied optics and composed of experimental and design tasks. The experimental tasks include the measurements of aberrations and major parameters of a primitive telescope, while in the design parts, the students are asked to design a Keplerian telescope. The whole course gives a deepened understandings on the concepts, assembling, and operating of telescopes. The students are also encouraged to extend their interests on other typical optical instruments.

Compensation of power drops in reflective semiconductor optical amplifier-based passive optical network with upstream data rate adjustment

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Chow, Chi-Wai; Chiang, Ming-Feng; Shih, Fu-Yuan; Pan, Ci-Ling

2011-09-01

In a wavelength division multiplexed-passive optical network (WDM-PON), different fiber lengths and optical components would introduce different power budgets to different optical networking units (ONUs). Besides, the power decay of the distributed optical carrier from the optical line terminal owing to aging of the optical transmitter could also reduce the injected power into the ONU. In this work, we propose and demonstrate a carrier distributed WDM-PON using a reflective semiconductor optical amplifier-based ONU that can adjust its upstream data rate to accommodate different injected optical powers. The WDM-PON is evaluated at standard-reach (25 km) and long-reach (100 km). Bit-error rate measurements at different injected optical powers and transmission lengths show that by adjusting the upstream data rate of the system (622 Mb/s, 1.25 and 2.5 Gb/s), error-free (<10-9) operation can still be achieved when the power budget drops.

Glass-based integrated optical splitters: engineering oriented research

NASA Astrophysics Data System (ADS)

Hao, Yinlei; Zheng, Weiwei; Yang, Jianyi; Jiang, Xiaoqing; Wang, Minghua

2010-10-01

Optical splitter is one of most typical device heavily demanded in implementation of Fiber To The Home (FTTH) system. Due to its compatibility with optical fibers, low propagation loss, flexibility, and most distinguishingly, potentially costeffectiveness, glass-based integrated optical splitters made by ion-exchange technology promise to be very attractive in application of optical communication networks. Aiming at integrated optical splitters applied in optical communication network, glass ion-exchange waveguide process is developed, which includes two steps: thermal salts ion-exchange and field-assisted ion-diffusion. By this process, high performance optical splitters are fabricated in specially melted glass substrate. Main performance parameters of these splitters, including maximum insertion loss (IL), polarization dependence loss (PDL), and IL uniformity are all in accordance with corresponding specifications in generic requirements for optic branching components (GR-1209-CORE). In this paper, glass based integrated optical splitters manufacturing is demonstrated, after which, engineering-oriented research work results on glass-based optical splitter are presented.

Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating

PubMed Central

Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

2015-01-01

Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing. PMID:26349444

Nanoimprint of a 3D structure on an optical fiber for light wavefront manipulation.

PubMed

Calafiore, Giuseppe; Koshelev, Alexander; Allen, Frances I; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

2016-09-16

Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. In this paper we report the fabrication of a three-dimensional structure achieved by direct nanoimprint lithography on the facet of an optical fiber. Nanoimprint processes and tools were specifically developed to enable a high lithographic accuracy and coaxial alignment of the optical device with respect to the fiber core. To demonstrate the capability of this new approach, a 3D beam splitter has been designed, imprinted and optically characterized. Scanning electron microscopy and optical measurements confirmed the good lithographic capabilities of the proposed approach as well as the desired optical performance of the imprinted structure. The inexpensive solution presented here should enable advancements in areas such as integrated optics and sensing, achieving enhanced portability and versatility of fiber optic components.

Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating

NASA Astrophysics Data System (ADS)

Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

2015-09-01

Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing.

Acousto-Optic and Linear Electro-Optic Properties of Organic Polymeric Materials

DTIC Science & Technology

1989-04-27

Naval Research Laboratory Washington, DC 20375-5000 NRL Memorandum Report 6454 od I3 Acousto - Optic and Linear Electro-Optic Properties of Organic...PROGRAM P1RC;EC7 ASK Arlington, VA 22217-5000 ELEMENT NO NO1 I1I TITLE (Include Security Classification) Acousto - Optic and Linear Electro-Optic...briefly discussing the important molecular properties for enhanced acousto ~ optic and electro-Ooptic ef fects and then relating these to "current

Feasibility of Optical Instruments Based on Multiaperture Optics.

DTIC Science & Technology

1984-10-16

system may be configured. The optical elements may be nonimaging concentrators (light horns), the field of view (FOV) of which may be controlled by a...RD-RI58 868 FEASIBILITY OF OPTICAL INSTRUMENTS BASED ON i/I MULTIAPERTURE OPTICS (U) FLORIDA UNIV GAINESVILLE DEPT OF NUCLEAR ENGINEERING SCIENCES J D...d Subtitle) 5. TYPE OF REPORT & PERIOD COVERED ’ 0 Feasibility of Optical Instruments Based on Final Report * CD Multiaperature Optics 615/83 to 9/30

High-speed, Low Voltage, Miniature Electro-optic Modulators Based on Hybrid Photonic-Crystal/Polymer/Sol-Gel Technology

DTIC Science & Technology

2012-02-01

code) 01/02/2012 FINAL 15/11/2008 - 15/11/2011 High-speed, Low Voltage, Miniature Electro - optic Modulators Based on Hybrid Photonic-Crystal/Polymer... optic modulator, silicon photonics, integrated optics, electro - optic polymer, avionics, optical communications, sol-gel, nanotechnology U U U UU 25...2011 Program Manager: Dr. Charles Y-C Lee High-speed, Low Voltage, Miniature Electro - optic Modulators Based on Hybrid Photonic-Crystal/Polymer/Sol

Polyhedral integrated and free space optical interconnection

DOEpatents

Erteza, I.A.

1998-01-06

An optical communication system uses holographic optical elements to provide guided wave and non-guided communication, resulting in high bandwidth, high connectivity optical communications. Holograms within holographic optical elements route optical signals between elements and between nodes connected to elements. Angular and wavelength multiplexing allow the elements to provide high connectivity. The combination of guided and non-guided communication allows compact polyhedral system geometries. Guided wave communications provided by multiplexed substrate-mode holographic optical elements eases system alignment. 7 figs.

Optical pumping in a whispering-mode optical waveguide

DOEpatents

Kurnit, N.A.

1981-08-11

A device and method for optical pumping in a whispering mode optical waveguide are described. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction path lengths which are achieved in a small volume.

Polyhedral integrated and free space optical interconnection

DOEpatents

Erteza, Ireena A.

1998-01-01

An optical communication system uses holographic optical elements to provide guided wave and non-guided communication, resulting in high bandwidth, high connectivity optical communications. Holograms within holographic optical elements route optical signals between elements and between nodes connected to elements. Angular and wavelength multiplexing allow the elements to provide high connectivity. The combination of guided and non-guided communication allows compact polyhedral system geometries. Guided wave communications provided by multiplexed substrate-mode holographic optical elements eases system alignment.

Center for Adaptive Optics | Publications

Science.gov Websites

Text-Only Version Adaptive Optics, Center for Home Page CfAO Logo Search The Center Adaptive Optics for Adaptive Optics | Search | Sitemap | The Center | Adaptive Optics | Research | Education/HR

Optical Eigenvector.

DTIC Science & Technology

1984-10-01

it necessary and identify by blckci -. mbrr, ’At tile bneginninp, of this contract , bot], -,-j- .lc the rest of the optical community imagined * that...simple analog optical computer,, could produce satisfactory solutions to elgenproblems. Earl’ - in this contract we improved optical computing... contract both we and the rest of the optical community imagined that simple analog optical computers could produce . satisfactory solutions to

Injection-seeded optical parametric oscillator and system

DOEpatents

Lucht, Robert P.; Kulatilaka, Waruna D.; Anderson, Thomas N.; Bougher, Thomas L.

2007-10-09

Optical parametric oscillators (OPO) and systems are provided. The OPO has a non-linear optical material located between two optical elements where the product of the reflection coefficients of the optical elements are higher at the output wavelength than at either the pump or idler wavelength. The OPO output may be amplified using an additional optical parametric amplifier (OPA) stage.

Optically Driven Q-Switches For Lasers

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

1994-01-01

Optically driven Q-switches for pulsed lasers proposed, taking place of acousto-optical, magneto-optical, and electro-optical switches. Optical switching beams of proposed Q-switching most likely generated in pulsed diode lasers or light-emitting diodes, outputs of which are amplitude-modulated easily by direct modulation of relatively small input currents. Energy efficiencies exceed those of electrically driven Q-switches.

Cryo-Infrared Optical Characterization at NASA GSFC

NASA Technical Reports Server (NTRS)

Boucarut, Ray; Quijada, Manuel A.; Henry, Ross M.

2004-01-01

The development of large space infrared optical systems, such as the Next Generation Space Telescope (NGST), has increased requirements for measurement accuracy in the optical properties of materials. Many materials used as optical components in infrared optical systems, have strong temperature dependence in their optical properties. Unfortunately, data on the temperature dependence of most of these materials is sparse. In this paper, we provide a description of the capabilities existing in the Optics Branch at the Goddard Space Flight Center that enable the characterization of the refractive index and absorption coefficient changes and other optical properties in infrared materials at cryogenic temperatures. Details of the experimental apparatus, which include continuous flow liquid helium optical cryostat, and a Fourier Transform Infrared (FTIR) spectrometer are discussed.

Study on multiple-hops performance of MOOC sequences-based optical labels for OPS networks

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun; Ma, Chunli

2009-11-01

In this paper, we utilize a new study method that is under independent case of multiple optical orthogonal codes to derive the probability function of MOOCS-OPS networks, discuss the performance characteristics for a variety of parameters, and compare some characteristics of the system employed by single optical orthogonal code or multiple optical orthogonal codes sequences-based optical labels. The performance of the system is also calculated, and our results verify that the method is effective. Additionally it is found that performance of MOOCS-OPS networks would, negatively, be worsened, compared with single optical orthogonal code-based optical label for optical packet switching (SOOC-OPS); however, MOOCS-OPS networks can greatly enlarge the scalability of optical packet switching networks.

Laser Safety Method For Duplex Open Loop Parallel Optical Link

DOEpatents

Baumgartner, Steven John; Hedin, Daniel Scott; Paschal, Matthew James

2003-12-02

A method and apparatus are provided to ensure that laser optical power does not exceed a "safe" level in an open loop parallel optical link in the event that a fiber optic ribbon cable is broken or otherwise severed. A duplex parallel optical link includes a transmitter and receiver pair and a fiber optic ribbon that includes a designated number of channels that cannot be split. The duplex transceiver includes a corresponding transmitter and receiver that are physically attached to each other and cannot be detached therefrom, so as to ensure safe, laser optical power in the event that the fiber optic ribbon cable is broken or severed. Safe optical power is ensured by redundant current and voltage safety checks.

Micro benchtop optics by bulk silicon micromachining

DOEpatents

Lee, Abraham P.; Pocha, Michael D.; McConaghy, Charles F.; Deri, Robert J.

2000-01-01

Micromachining of bulk silicon utilizing the parallel etching characteristics of bulk silicon and integrating the parallel etch planes of silicon with silicon wafer bonding and impurity doping, enables the fabrication of on-chip optics with in situ aligned etched grooves for optical fibers, micro-lenses, photodiodes, and laser diodes. Other optical components that can be microfabricated and integrated include semi-transparent beam splitters, micro-optical scanners, pinholes, optical gratings, micro-optical filters, etc. Micromachining of bulk silicon utilizing the parallel etching characteristics thereof can be utilized to develop miniaturization of bio-instrumentation such as wavelength monitoring by fluorescence spectrometers, and other miniaturized optical systems such as Fabry-Perot interferometry for filtering of wavelengths, tunable cavity lasers, micro-holography modules, and wavelength splitters for optical communication systems.

Optical source and apparatus for remote sensing

NASA Technical Reports Server (NTRS)

Coyle, Donald Barry (Inventor)

2011-01-01

An optical amplifier is configured to amplify an injected seed optical pulse. The optical amplifier may include two or more gain sections coupled to form a continuous solid waveguide along a primary optical path. Each gain section may include: (i) an optical isolator forming an input to that gain section; (ii) a doped optical fiber having a first end coupled to the optical isolator and having a second end; (iii) a plurality of pump laser diodes; (iv) a controller providing drive signals to each of the plurality, the controller being configured to provide at least pulsed drive signals; and (v) an optical coupler having a first input port coupled to the second end, and a second input port coupled to the plurality and an output port.

Multifocal visual evoked potential in optic neuritis, ischemic optic neuropathy and compressive optic neuropathy

PubMed Central

Jayaraman, Manju; Gandhi, Rashmin Anilkumar; Ravi, Priya; Sen, Parveen

2014-01-01

Purpose: To investigate the effect of optic neuritis (ON), ischemic optic neuropathy (ION) and compressive optic neuropathy (CON) on multifocal visual evoked potential (mfVEP) amplitudes and latencies, and to compare the parameters among three optic nerve disorders. Materials and Methods: mfVEP was recorded for 71 eyes of controls and 48 eyes of optic nerve disorders with subgroups of optic neuritis (ON, n = 21 eyes), ischemic optic neuropathy (ION, n = 14 eyes), and compressive optic neuropathy (CON, n = 13 eyes). The size of defect in mfVEP amplitude probability plots and relative latency plots were analyzed. The pattern of the defect in amplitude probability plot was classified according to the visual field profile of optic neuritis treatment trail (ONTT). Results: Median of mfVEP amplitude (log SNR) averaged across 60 sectors were reduced in ON (0.17 (0.13-0.33)), ION (0.14 (0.12-0.21)) and CON (0.21 (0.14-0.30)) when compared to controls. The median mfVEP relative latencies compared to controls were significantly prolonged in ON and CON group of 10.53 (2.62-15.50) ms and 5.73 (2.67-14.14) ms respectively compared to ION group (2.06 (-4.09-13.02)). The common mfVEP amplitude defects observed in probability plots were diffuse pattern in ON, inferior altitudinal defect in ION and temporal hemianopia in CON eyes. Conclusions: Optic nerve disorders cause reduction in mfVEP amplitudes. The extent of delayed latency noted in ischemic optic neuropathy was significantly lesser compared to subjects with optic neuritis and compressive optic neuropathy. mfVEP amplitudes can be used to objectively assess the topography of the visual field defect. PMID:24088641

Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures.

PubMed

Wang, Congjun; Ohodnicki, Paul R; Su, Xin; Keller, Murphy; Brown, Thomas D; Baltrus, John P

2015-02-14

Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices.

RGC Neuroprotection Following Optic Nerve Trauma Mediated By Intranasal Delivery of Amnion Cell Secretome

PubMed Central

Grinblat, Gabriela A.; Khan, Reas S.; Dine, Kimberly; Wessel, Howard; Brown, Larry; Shindler, Kenneth S.

2018-01-01

Purpose Intranasally delivered ST266, the biological, proteinaceous secretome of amnion-derived multipotent progenitor cells, reduces retinal ganglion cell (RGC) loss, optic nerve inflammation, and demyelination in experimental optic neuritis. This unique therapy and novel administration route delivers numerous cytokines and growth factors to the eye and optic nerve, suggesting a potential to also treat other optic neuropathies. Thus, ST266-mediated neuroprotection was examined following traumatic optic nerve injury. Methods Optic nerve crush injury was surgically induced in C57BL/6J mice. Mice were treated daily with intranasal PBS or ST266. RGC function was assessed by optokinetic responses (OKRs), RGCs were counted, and optic nerve sections were stained with luxol fast blue and anti-neurofilament antibodies to assess myelin and RGC axon damage. Results Intranasal ST266 administered daily for 5 days, beginning at the time that a 1-second optic nerve crush was performed, significantly attenuated OKR decreases. Furthermore, ST266 treatment reduced damage to RGC axons and myelin within optic nerves, and blocked RGC loss. Following a 4-second optic nerve crush, intranasal ST266 increased RGC survival and showed a trend toward reduced RGC axon and myelin damage. Ten days following optic nerve crush, ST266 prevented myelin damage, while also inducing a trend toward increased RGC survival and visual function. Conclusions ST266 significantly attenuates traumatic optic neuropathy. Neuroprotective effects of this unique combination of biologic molecules observed here and previously in optic neuritis suggest potential broad application for preventing neuronal damage in multiple optic nerve disorders. Furthermore, results support intranasal delivery as a novel, noninvasive therapeutic modality for eyes and optic nerves. PMID:29847652

Optical Vector Near-Field Imaging for the Design of Impedance Matched Optical Antennas and Devices

NASA Astrophysics Data System (ADS)

Olmon, Robert L.

Antennas control and confine electromagnetic energy, transforming free-space propagating modes to localized regions. This is not only true for the traditional classical radio antenna, but also for structures that interact resonantly at frequencies throughout the visible regime, that are on the micro- and nanometer size scales. The investigation of these optical antennas has increased dramatically in recent years. They promise to bring the transformative capabilities of radio antennas to the nanoscale in fields such as plasmonics, photonics, spectroscopy, and microscopy. However, designing optical antennas with desired properties is not straightforward due to different material properties and geometric considerations in the optical regime compared to the RF. New antenna characterization tools and techniques must be developed for the optical frequency range. Here, the optical analogue of the vector network analyzer, based on a scattering-type scanning near-field optical microscope, is described and demonstrated for the investigation of the electric and magnetic properties of optical antennas through their electromagnetic vector near-field. Specifically, bringing this microwave frequency tool to the optical regime enables the study of antenna resonant length scaling, optical frequency electromagnetic parameters including current density and impedance, optical antenna coupling to waveguides and nanoloads, local electric field enhancement, and electromagnetic duality of complementary optical antenna geometries.

Optical field encryption for secure transmission of data

NASA Astrophysics Data System (ADS)

Fraser, Colin B.; Harvey, Andrew R.

2004-12-01

The growing awareness of the vulnerability of information transmitted on communication systems within the government, military and commercial sectors, has stimulated a number of areas of research within the optical community to design optical hardware encryption systems providing inherent immunity to espionage techniques. This paper describes a hardware optical encryption technique that utilises off the shelf telecommunication equipment and negates the necessity for an independent key distribution system with respect to the data transmission system, as is common with alternative encryption system implementations. This method also lends itself easily to fiber optic or free space communication and is applicable within any optical waveband. The encryption-decryption of the optical signal is achieved through low coherence optical interferometry. This requires the instantaneous processing and analysis of the signal, optically, to retrieve the relevant optical phase information hidden in the transmitted optical noise. This technology allows an authorised user to transmit encrypted information at a high data rate securely, while maintaining opaqueness to an unauthorised observer that data transmission is occurring. As the instantaneous optical field properties of the signals present in the system are essential to the optical encryption - decryption process, the system is inherently protected against electronic recording and advances in computational decryption algorithms. For organisations wishing to protect sensitive data and levels of communication activity these are highly desirable features.

Optics detection and laser countermeasures on a combat vehicle

NASA Astrophysics Data System (ADS)

Sjöqvist, Lars; Allard, Lars; Pettersson, Magnus; Börjesson, Per; Lindskog, Nils; Bodin, Johan; Widén, Anders; Persson, Hâkan; Fredriksson, Jan; Edström, Sten

2016-10-01

Magnifying optical assemblies used for weapon guidance or rifle scopes may possess a threat for a combat vehicle and its personnel. Detection and localisation of optical threats is consequently of interest in military applications. Typically a laser system is used in optics detection, or optical augmentation, to interrogate a scene of interest to localise retroreflected laser radiation. One interesting approach for implementing optics detection on a combat vehicle is to use a continuous scanning scheme. In addition, optics detection can be combined with laser countermeasures, or a laser dazzling function, to efficiently counter an optical threat. An optics detection laser sensor demonstrator has been implemented on a combat vehicle. The sensor consists of a stabilised gimbal and was integrated together with a LEMUR remote electro-optical sight. A narrow laser slit is continuously scanned around the horizon to detect and locate optical threats. Detected threats are presented for the operator within the LEMUR presentation system, and by cueing a countermeasure laser installed in the LEMUR sensor housing threats can be defeated. Results obtained during a field demonstration of the optics detection sensor and the countermeasure laser will be presented. In addition, results obtained using a dual-channel optics detection system designed for false alarm reduction are also discussed.

Modified-Signed-Digit Optical Computing Using Fan-Out

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang; Zhou, Shaomin; Yeh, Pochi

1996-01-01

Experimental optical computing system containing optical fan-out elements implements modified signed-digit (MSD) arithmetic and logic. In comparison with previous optical implementations of MSD arithmetic, this one characterized by larger throughput, greater flexibility, and simpler optics.

Nonlinear optical whispering gallery mode resonators

NASA Technical Reports Server (NTRS)

Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor)

2005-01-01

Whispering gallery mode (WGM) optical resonators comprising nonlinear optical materials, where the nonlinear optical material of a WGM resonator includes a plurality of sectors within the optical resonator and nonlinear coefficients of two adjacent sectors are oppositely poled.

Review of optical memory technologies

NASA Technical Reports Server (NTRS)

Chen, D.

1972-01-01

Optical technologies for meeting the demands of large capacity fast access time memory are discussed in terms of optical phenomena and laser applications. The magneto-optic and electro-optic approaches are considered to be the most promising memory approaches.

Method and device for remotely monitoring an area using a low peak power optical pump

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.; Jain, Jinesh C.

2014-07-22

A method and device for remotely monitoring an area using a low peak power optical pump comprising one or more pumping sources, one or more lasers; and an optical response analyzer. Each pumping source creates a pumping energy. The lasers each comprise a high reflectivity mirror, a laser media, an output coupler, and an output lens. Each laser media is made of a material that emits a lasing power when exposed to pumping energy. Each laser media is optically connected to and positioned between a corresponding high reflectivity mirror and output coupler along a pumping axis. Each output coupler is optically connected to a corresponding output lens along the pumping axis. The high reflectivity mirror of each laser is optically connected to an optical pumping source from the one or more optical pumping sources via an optical connection comprising one or more first optical fibers.

Cloud and aerosol optical depths

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Russell, P. B.; Ackerman, Thomas P.; Colburn, D. C.; Wrigley, R. C.; Spanner, M. A.; Livingston, J. M.

1988-01-01

An airborne Sun photometer was used to measure optical depths in clear atmospheres between the appearances of broken stratus clouds, and the optical depths in the vicinity of smokes. Results show that (human) activities can alter the chemical and optical properties of background atmospheres to affect their spectral optical depths. Effects of water vapor adsorption on aerosol optical depths are apparent, based on data of the water vapor absorption band centered around 940 nm. Smoke optical depths show increases above the background atmosphere by up to two orders of magnitude. When the total optical depths measured through clouds were corrected for molecular scattering and gaseous absorption by subtracting the total optical depths measured through the background atmosphere, the resultant values are lower than those of the background aerosol at short wavelengths. The spectral dependence of these cloud optical depths is neutral, however, in contrast to that of the background aerosol or the molecular atmosphere.

Method and apparatus for optical phase error correction

DOEpatents

DeRose, Christopher; Bender, Daniel A.

2014-09-02

The phase value of a phase-sensitive optical device, which includes an optical transport region, is modified by laser processing. At least a portion of the optical transport region is exposed to a laser beam such that the phase value is changed from a first phase value to a second phase value, where the second phase value is different from the first phase value. The portion of the optical transport region that is exposed to the laser beam can be a surface of the optical transport region or a portion of the volume of the optical transport region. In an embodiment of the invention, the phase value of the optical device is corrected by laser processing. At least a portion of the optical transport region is exposed to a laser beam until the phase value of the optical device is within a specified tolerance of a target phase value.

Optical CDMA components requirements

NASA Astrophysics Data System (ADS)

Chan, James K.

1998-08-01

Optical CDMA is a complementary multiple access technology to WDMA. Optical CDMA potentially provides a large number of virtual optical channels for IXC, LEC and CLEC or supports a large number of high-speed users in LAN. In a network, it provides asynchronous, multi-rate, multi-user communication with network scalability, re-configurability (bandwidth on demand), and network security (provided by inherent CDMA coding). However, optical CDMA technology is less mature in comparison to WDMA. The components requirements are also different from WDMA. We have demonstrated a video transport/switching system over a distance of 40 Km using discrete optical components in our laboratory. We are currently pursuing PIC implementation. In this paper, we will describe the optical CDMA concept/features, the demonstration system, and the requirements of some critical optical components such as broadband optical source, broadband optical amplifier, spectral spreading/de- spreading, and fixed/programmable mask.

Characterization of light transmissions in various optical fibers with proton beam

NASA Astrophysics Data System (ADS)

Song, Young Beom; Kim, Hye Jin; Kim, Mingeon; Lee, Bongsoo; Shin, Sang Hun; Yoo, Wook Jae; Jang, Kyoung Won; Hwang, Sung Won

2017-12-01

As a feasibility study on the development of a fiber-optic radiation sensor for proton therapy dosimetry, we characterized light transmissions of various commercial optical fibers such as silica and plastic based optical fibers by the irradiation of proton beams. In this study, we measured light transmission spectra of optical fibers as a function of absorbed doses of proton beams using a deuterium & tungsten halogen lamps and a spectrometer. To be used as a fiber-optic radiation sensor, the optical fibers should have the radiation resistant characteristics and provide stable output signals during the proton beam irradiation. In this study, we could select suitable optical fibers to be used in the fiber-optic radiation sensor without quenching effects for proton therapy dosimetry. As a result, the light transmittance of the optical fibers had decreasing trends with increasing absorbed dose as expected.

Photonic-powered cable assembly

DOEpatents

Sanderson, Stephen N.; Appel, Titus James; Wrye, IV, Walter C.

2013-01-22

A photonic-cable assembly includes a power source cable connector ("PSCC") coupled to a power receive cable connector ("PRCC") via a fiber cable. The PSCC electrically connects to a first electronic device and houses a photonic power source and an optical data transmitter. The fiber cable includes an optical transmit data path coupled to the optical data transmitter, an optical power path coupled to the photonic power source, and an optical feedback path coupled to provide feedback control to the photonic power source. The PRCC electrically connects to a second electronic device and houses an optical data receiver coupled to the optical transmit data path, a feedback controller coupled to the optical feedback path to control the photonic power source, and a photonic power converter coupled to the optical power path to convert photonic energy received over the optical power path to electrical energy to power components of the PRCC.

Photonic-powered cable assembly

DOEpatents

Sanderson, Stephen N; Appel, Titus James; Wrye, IV, Walter C

2014-06-24

A photonic-cable assembly includes a power source cable connector ("PSCC") coupled to a power receive cable connector ("PRCC") via a fiber cable. The PSCC electrically connects to a first electronic device and houses a photonic power source and an optical data transmitter. The fiber cable includes an optical transmit data path coupled to the optical data transmitter, an optical power path coupled to the photonic power source, and an optical feedback path coupled to provide feedback control to the photonic power source. The PRCC electrically connects to a second electronic device and houses an optical data receiver coupled to the optical transmit data path, a feedback controller coupled to the optical feedback path to control the photonic power source, and a photonic power converter coupled to the optical power path to convert photonic energy received over the optical power path to electrical energy to power components of the PRCC.

Microfiber Optical Sensors: A Review

PubMed Central

Lou, Jingyi; Wang, Yipei; Tong, Limin

2014-01-01

With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, fast response, high flexibility and low optical power consumption. Here we review recent progress in microfiber optical sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber optical sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber optical sensors. PMID:24670720

On the development status of high performance silicon pore optics for future x-ray telescopes

NASA Astrophysics Data System (ADS)

Kraft, Stefan; Collon, M.; Günther, R.; Partapsing, R.; Beijersbergen, M.; Bavdaz, M.; Lumb, D.; Peacock, A.; Wallace, K.

2017-11-01

Silicon pore optics have been proposed earlier as modular optical X-ray units in large Wolter-I telescopes that would match effective area and resolution requirements imposed by missions such as XEUS. Since then the optics have been developed further and the feasibility of the production of high-performance pore optics has been demonstrated. Optimisation of both the production and the assembly process allowed the generation of optics with larger areas with improved imaging performance. Silicon pore optics can now be manufactured with properties required for future X-ray telescopes. A suitable design that allows the implementation of pore optics into X-ray Optical Units in Wolter-I configuration was recently derived including an appropriate telescope mounting structure with interfaces for the individual components. The development status, the achieved performance and the requirements regarding future mirror production, optics assembly and related metrology for its characterisation are presented.

All-optical virtual private network and ONUs communication in optical OFDM-based PON system.

PubMed

Zhang, Chongfu; Huang, Jian; Chen, Chen; Qiu, Kun

2011-11-21

We propose and demonstrate a novel scheme, which enables all-optical virtual private network (VPN) and all-optical optical network units (ONUs) inter-communications in optical orthogonal frequency-division multiplexing-based passive optical network (OFDM-PON) system using the subcarrier bands allocation for the first time (to our knowledge). We consider the intra-VPN and inter-VPN communications which correspond to two different cases: VPN communication among ONUs in one group and in different groups. The proposed scheme can provide the enhanced security and a more flexible configuration for VPN users compared to the VPN in WDM-PON or TDM-PON systems. The all-optical VPN and inter-ONU communications at 10-Gbit/s with 16 quadrature amplitude modulation (16 QAM) for the proposed optical OFDM-PON system are demonstrated. These results verify that the proposed scheme is feasible. © 2011 Optical Society of America

A multi-ring optical packet and circuit integrated network with optical buffering.

PubMed

Furukawa, Hideaki; Shinada, Satoshi; Miyazawa, Takaya; Harai, Hiroaki; Kawasaki, Wataru; Saito, Tatsuhiko; Matsunaga, Koji; Toyozumi, Tatuya; Wada, Naoya

2012-12-17

We newly developed a 3 × 3 integrated optical packet and circuit switch-node. Optical buffers and burst-mode erbium-doped fiber amplifiers with the gain flatness are installed in the 3 × 3 switch-node. The optical buffer can prevent packet collisions and decrease packet loss. We constructed a multi-ring optical packet and circuit integrated network testbed connecting two single-ring networks and a client network by the 3 × 3 switch-node. For the first time, we demonstrated 244 km fiber transmission and 5-node hopping of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10 Gigabit Ethernet frames on the testbed. Error-free (frame error rate < 1 × 10(-4)) operation was achieved with optical packets of various packet lengths. In addition, successful avoidance of packet collisions by optical buffers was confirmed.

Evaluation of insertion characteristics of less invasive Si optoneural probe with embedded optical fiber

NASA Astrophysics Data System (ADS)

Morikawa, Takumi; Harashima, Takuya; Kino, Hisashi; Fukushima, Takafumi; Tanaka, Tetsu

2017-04-01

A less invasive Si optoneural probe with an embedded optical fiber was proposed and successfully fabricated. The diameter of the optical fiber was completely controlled by hydrogen fluoride etching, and the thinned optical fiber can propagate light without any leakage. This optical fiber was embedded in a trench formed inside a probe shank, which causes less damage to tissues. In addition, it was confirmed that the optical fiber embedded in the probe shank successfully irradiated light to optically stimulate gene transfected neurons. The electrochemical impedance of the probe did not change despite the light irradiation. Furthermore, probe insertion characteristics were evaluated in detail and less invasive insertion was clearly indicated for the Si optoneural probe with the embedded optical fiber compared with conventional optical neural probes. This neural probe with the embedded optical fiber can be used as a simple and easy tool for optogenetics and brain science.

Absolute calibration of optical flats

DOEpatents

Sommargren, Gary E.

2005-04-05

The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

Piezo-optic and elasto-optic properties of monoclinic triglycine sulfate crystals.

PubMed

Mytsyk, Bogdan; Demyanyshyn, Natalya; Erba, Alessandro; Shut, Viktor; Mozzharov, Sergey; Kost, Yaroslav; Mys, Oksana; Vlokh, Rostyslav

2017-12-01

For the first time, to the best of our knowledge, we have experimentally determined all of the components of the piezo-optic tensor for monoclinic crystals. This has been implemented on a specific example of triglycine sulfate crystals. Based on the results obtained, the complete elasto-optic tensor has been calculated. Acousto-optic figures of merit (AOFMs) have been estimated for the case of acousto-optic interaction occurring in the principal planes of the optical indicatrix ellipsoid and for geometries in which the highest elasto-optic coefficients are involved as effective parameters. It has been found that the highest AOFM value is equal to 6.8×10 -15   s 3 /kg for the case of isotropic acousto-optic interaction with quasi-longitudinal acoustic waves in the principal planes. This AOFM is higher than the corresponding values typical for canonic acousto-optic materials, which are transparent in the deep ultraviolet spectral range.

Evaluation of acute radiation optic neuropathy by B-scan ultrasonography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovato, A.A.; Char, D.H.; Quivey, J.M.

1990-09-15

We studied the accuracy of B-scan ultrasonography to diagnose radiation-induced optic neuropathy in 15 patients with uveal melanoma. Optic neuropathy was diagnosed by an observer masked as to clinical and photographic data. We analyzed planimetry area measurements of the retrobulbar nerve before and after irradiation. The retrobulbar area of the optic nerve shadow on B-scan was quantitated with a sonic digitizer. Increased optic nerve shadow area was confirmed in 13 of 15 patients who had radiation optic neuropathy (P less than .004). The correct diagnosis was confirmed when the results of ultrasound were compared to fundus photography and fluorescein angiography.more » In 13 patients there was acute radiation optic neuropathy. Two patients did not show an enlarged retrobulbar optic nerve, and the clinical appearance suggested early progression to optic atrophy. Ultrasonography documents the enlargement of the optic nerve caused by acute radiation changes.« less

3D printing of tissue-simulating phantoms as a traceable standard for biomedical optical measurement

NASA Astrophysics Data System (ADS)

Dong, Erbao; Wang, Minjie; Shen, Shuwei; Han, Yilin; Wu, Qiang; Xu, Ronald

2016-01-01

Optical phantoms are commonly used to validate and calibrate biomedical optical devices in order to ensure accurate measurement of optical properties in biological tissue. However, commonly used optical phantoms are based on homogenous materials that reflect neither optical properties nor multi-layer heterogeneities of biological tissue. Using these phantoms for optical calibration may result in significant bias in biological measurement. We propose to characterize and fabricate tissue simulating phantoms that simulate not only the multi-layer heterogeneities but also optical properties of biological tissue. The tissue characterization module detects tissue structural and functional properties in vivo. The phantom printing module generates 3D tissue structures at different scales by layer-by-layer deposition of phantom materials with different optical properties. The ultimate goal is to fabricate multi-layer tissue simulating phantoms as a traceable standard for optimal calibration of biomedical optical spectral devices.

Synthetic-lattice enabled all-optical devices based on orbital angular momentum of light.

PubMed

Luo, Xi-Wang; Zhou, Xingxiang; Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can; Zhang, Chuanwei; Zhou, Zheng-Wei

2017-07-14

All-optical photonic devices are crucial for many important photonic technologies and applications, ranging from optical communication to quantum information processing. Conventional design of all-optical devices is based on photon propagation and interference in real space, which may rely on large numbers of optical elements, and the requirement of precise control makes this approach challenging. Here we propose an unconventional route for engineering all-optical devices using the photon's internal degrees of freedom, which form photonic crystals in such synthetic dimensions for photon propagation and interference. We demonstrate this design concept by showing how important optical devices such as quantum memory and optical filters can be realized using synthetic orbital angular momentum (OAM) lattices in degenerate cavities. The design route utilizing synthetic photonic lattices may significantly reduce the requirement for numerous optical elements and their fine tuning in conventional design, paving the way for realistic all-optical photonic devices with novel functionalities.

Thermal casting of polymers in centrifuge for producing X-ray optics

DOEpatents

Hill, Randy M [Livermore, CA; Decker, Todd A [Livermore, CA

2012-03-27

An optic is produced by the steps of placing a polymer inside a rotateable cylindrical chamber, the rotateable cylindrical chamber having an outside wall, rotating the cylindrical chamber, heating the rotating chamber forcing the polymer to the outside wall of the cylindrical chamber, allowing the rotateable cylindrical chamber to cool while rotating producing an optic substrate with a substrate surface, sizing the optic substrate, and coating the substrate surface of the optic substrate to produce the optic with an optic surface.

Improved Optical Fiber Chemical Sensors

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

Calculations, based on exact theory of optical fiber, have shown how to increase optical efficiency sensitivity of active-core, step-index-profile optical-fiber fluorosensor. Calculations result of efforts to improve efficiency of optical-fiber chemical sensor of previous concept described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525). Optical fiber chemical detector of enhanced sensitivity made in several configurations. Portion of fluorescence or chemiluminescence generated in core, and launched directly into bound electromagnetic modes that propagate along core to photodetector.

Piezo-optic, photoelastic, and acousto-optic properties of SrB4O7 crystals.

PubMed

Mytsyk, Bohdan; Demyanyshyn, Natalia; Martynyuk-Lototska, Irina; Vlokh, Rostyslav

2011-07-20

On the basis of studies of the piezo-optic effect, it has been shown that SrB(4)O(7) crystals can be used as efficient acousto-optic materials in the vacuum ultraviolet spectral range. The full matrices of piezo-optic and photoelastic coefficients have been experimentally obtained for these crystals. The acousto-optic figure of merit and the diffraction efficiency have been estimated for both the visible and deep ultraviolet spectral ranges. © 2011 Optical Society of America

Preparation, optical and non-linear optical power limiting properties of Cu, CuNi nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Udayabhaskar, R.; Karthikeyan, B., E-mail: bkarthik@nitt.edu; Ollakkan, Muhamed Shafi

2014-01-06

Metallic nanowires show excellent Plasmon absorption which is tunable based on its aspect ratio and alloying nature. We prepared Cu and CuNi metallic nanowires and studied its optical and nonlinear optical behavior. Optical properties of nanowires are theoretically explained using Gans theory. Nonlinear optical behavior is studied using a single beam open aperture z-scan method with the use of 5 ns Nd: YAG laser. Optical limiting is found to arise from two-photon absorption.

Preparation, optical and non-linear optical power limiting properties of Cu, CuNi nanowires

NASA Astrophysics Data System (ADS)

Udayabhaskar, R.; Ollakkan, Muhamed Shafi; Karthikeyan, B.

2014-01-01

Metallic nanowires show excellent Plasmon absorption which is tunable based on its aspect ratio and alloying nature. We prepared Cu and CuNi metallic nanowires and studied its optical and nonlinear optical behavior. Optical properties of nanowires are theoretically explained using Gans theory. Nonlinear optical behavior is studied using a single beam open aperture z-scan method with the use of 5 ns Nd: YAG laser. Optical limiting is found to arise from two-photon absorption.

Analysis of Polarizing Optical Systems for Digital Optical Computing with Symmetric Self Electrooptic Devices

DTIC Science & Technology

1991-03-31

I AD-A232 768 I Annual Report Analysis of Polarizing Optical Systems for Digital Optical Computing with I ’ Symmetric Self Electrooptic Devices I To...TTU AND SuSiIU S. PUNDIN mUMBERS Polarizing Optical Systems for Digital Optical Computing with Symmetric Self Electrooptic Devices AFOSR-89-0542 C...UTION COO$ UNLIMITED 13. ABSTRACT (MAxnum00woUw Two architectural approaches have dominated the field of optical computing . The first appAch uses

Navigation-guided optic canal decompression for traumatic optic neuropathy: Two case reports.

PubMed

Bhattacharjee, Kasturi; Serasiya, Samir; Kapoor, Deepika; Bhattacharjee, Harsha

2018-06-01

Two cases of traumatic optic neuropathy presented with profound loss of vision. Both cases received a course of intravenous corticosteroids elsewhere but did not improve. They underwent Navigation guided optic canal decompression via external transcaruncular approach, following which both cases showed visual improvement. Postoperative Visual Evoked Potential and optical coherence technology of Retinal nerve fibre layer showed improvement. These case reports emphasize on the role of stereotactic navigation technology for optic canal decompression in cases of traumatic optic neuropathy.

Method And Apparatus For Coupling Optical Elements To Optoelectronic Devices For Manufacturing Optical Transceiver Modules

DOEpatents

Anderson, Gene R.; Armendariz, Marcelino G.; Bryan, Robert P.; Carson, Richard F.; Chu, Dahwey; Duckett, III, Edwin B.; Giunta, Rachel Knudsen; Mitchell, Robert T.; McCormick, Frederick B.; Peterson, David W.; Rising, Merideth A.; Reber, Cathleen A.; Reysen, Bill H.

2005-06-14

A process is provided for aligning and connecting at least one optical fiber to at least one optoelectronic device so as to couple light between at least one optical fiber and at least one optoelectronic device. One embodiment of this process comprises the following steps: (1) holding at least one optical element close to at least one optoelectronic device, at least one optical element having at least a first end; (2) aligning at least one optical element with at least one optoelectronic device; (3) depositing a first non-opaque material on a first end of at least one optoelectronic device; and (4) bringing the first end of at least one optical element proximate to the first end of at least one optoelectronic device in such a manner that the first non-opaque material contacts the first end of at least one optoelectronic device and the first end of at least one optical element. The optical element may be an optical fiber, and the optoelectronic device may be a vertical cavity surface emitting laser. The first non-opaque material may be a UV optical adhesive that provides an optical path and mechanical stability. In another embodiment of the alignment process, the first end of at least one optical element is brought proximate to the first end of at least one optoelectronic device in such a manner that an interstitial space exists between the first end of at least one optoelectronic device and the first end of at least one optical element.

Design principles and realization of electro-optical circuit boards

NASA Astrophysics Data System (ADS)

Betschon, Felix; Lamprecht, Tobias; Halter, Markus; Beyer, Stefan; Peterson, Harry

2013-02-01

The manufacturing of electro-optical circuit boards (EOCB) is based to a large extent on established technologies. First products with embedded polymer waveguides are currently produced in series. The range of applications within the sensor and data communication markets is growing with the increasing maturity level. EOCBs require design flows, processes and techniques similar to existing printed circuit board (PCB) manufacturing and appropriate for optical signal transmission. A key aspect is the precise and automated assembly of active and passive optical components to the optical waveguides which has to be supported by the technology. The design flow is described after a short introduction into the build-up of EOCBs and the motivation for the usage of this technology within the different application fields. Basis for the design of EOCBs are the required optical signal transmission properties. Thereafter, the devices for the electro-optical conversion are chosen and the optical coupling approach is defined. Then, the planar optical elements (waveguides, splitters, couplers) are designed and simulated. This phase already requires co-design of the optical and electrical domain using novel design flows. The actual integration of an optical system into a PCB is shown in the last part. The optical layer is thereby laminated to the purely electrical PCB using a conventional PCB-lamination process to form the EOCB. The precise alignment of the various electrical and optical layers is thereby essential. Electrical vias are then generated, penetrating also the optical layer, to connect the individual electrical layers. Finally, the board has to be tested electrically and optically.

Research Studies on Advanced Optical Module/Head Designs for Optical Disk Recording Devices

NASA Technical Reports Server (NTRS)

Burke, James J.; Seery, Bernard D.

1993-01-01

The Annual Report of the Optical Data Storage Center of the University of Arizona is presented. Summary reports on continuing projects are presented. Research areas include: magneto-optic media, optical heads, and signal processing.

Stem Cell Ophthalmology Treatment Study II

ClinicalTrials.gov

2018-02-01

Retinal Disease; Age-Related Macular Degeneration; Retinitis Pigmentosa; Stargardt Disease; Optic Neuropathy; Nonarteritic Ischemic Optic Neuropathy; Optic Atrophy; Optic Nerve Disease; Glaucoma; Leber Hereditary Optic Neuropathy; Blindness; Vision Loss Night; Vision Loss Partial; Vision, Low; Retinopathy; Maculopathy; Macular Degeneration; Retina Atrophy

Simulation, Measurements and Image Processing for Capillary Optical Digital Mammography

DTIC Science & Technology

2000-07-01

is the length of the optic. For a point P on the film, scattered radiation could come from any direction in the solid angle Qpatient , which is the...optic p .’optic - N, = T + npatient (13) where Ns-optic is the number of scattered x rays with the optic, N, is the number of scattered x rays without

Deoxyribonucleic acid (DNA)-based optical materials

NASA Astrophysics Data System (ADS)

Grote, James G.; Heckman, Emily M.; Hagen, Joshua A.; Yaney, Perry P.; Subramanyam, Guru; Clarson, Stephen J.; Diggs, Darnell E.; Nelson, Robert L.; Zetts, John S.; Hopkins, F. Kenneth; Ogata, Naoya

2004-12-01

Optical materials for waveguiding applications must possess the desired optical and electromagnetic properties for optimal device performance. Purified deoxyribonucleic acid (DNA), derived from salmon sperm, has been investigated for use as an optical waveguide material. In this paper we present the materials processing and optical and electromagnetic characterization of this purified DNA to render a high quality, low loss optical waveguide material.

Optical Neural Interfaces

PubMed Central

Warden, Melissa R.; Cardin, Jessica A.; Deisseroth, Karl

2014-01-01

Genetically encoded optical actuators and indicators have changed the landscape of neuroscience, enabling targetable control and readout of specific components of intact neural circuits in behaving animals. Here, we review the development of optical neural interfaces, focusing on hardware designed for optical control of neural activity, integrated optical control and electrical readout, and optical readout of population and single-cell neural activity in freely moving mammals. PMID:25014785

Optical alignment of high resolution Fourier transform spectrometers

NASA Technical Reports Server (NTRS)

Breckinridge, J. B.; Ocallaghan, F. G.; Cassie, A. G.

1980-01-01

Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

Research in Optical Symbolic Tasks

DTIC Science & Technology

1989-11-29

November 1989. Specifically, we have concentrated on the following topics: complexity studies for optical neural and digital systems, architecture and...1989. Specifically, we hav, concentrated on the following topics: complexity studies for optical neural and digital systems, architecture and models for...Digital Systems 1.1 Digital Optical Parallel System Complexity Our study of digital optical system complexity has included a comparison of optical and

System and method for attitude determination based on optical imaging

NASA Technical Reports Server (NTRS)

Junkins, John L. (Inventor); Pollock, Thomas C. (Inventor); Mortari, Daniele (Inventor)

2003-01-01

A method and apparatus is provide for receiving a first set of optical data from a first field of view and receiving a second set of optical data from a second field of view. A portion of the first set of optical data is communicated and a portion of the second set of optical data is reflected, both toward an optical combiner. The optical combiner then focuses the portions onto the image plane such that information at the image plane that is associated with the first and second fields of view is received by an optical detector and used to determine an attitude characteristic.

Current developments in optical engineering and commercial optics; Proceedings of the Meeting, San Diego, CA, Aug. 7-11, 1989

NASA Technical Reports Server (NTRS)

Fischer, Robert E. (Editor); Pollicove, Harvey M. (Editor); Smith, Warren J. (Editor)

1989-01-01

Various papers on current developments in optical engineering and commercial optics are presented. Individual topics addressed include: large optics fabrication technology drivers and new manufacturing techniques, new technology for beryllium mirror production, design examples of hybrid refractive-diffractive lenses, optical sensor designs for detecting cracks in optical materials, retroreflector field-of-view properties for open and solid cube corners, correction of misalignment-dependent aberrations of the HST via phase retrieval, basic radiometry review for seeker test set, radiation effects on visible optical elements, and nonlinear simulation of efficiency for large-orbit nonwiggler FELs.

Method and apparatus for bistable optical information storage for erasable optical disks

DOEpatents

Land, Cecil E.; McKinney, Ira D.

1990-01-01

A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in an lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk.

Method and apparatus for bistable optical information storage for erasable optical disks

DOEpatents

Land, C.E.; McKinney, I.D.

1988-05-31

A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in a lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk. 10 figs.

Optics & Materials Science & Technology (OMST) Organization at LLNL

ScienceCinema

Suratwala,; Tayyab,; Nguyen, Hoang; Bude, Jeff; Dylla-Spears, Rebecca

2018-06-13

The Optics and Materials Science & Technology (OMST) organization at Lawrence Livermore National Laboratory (LLNL) supplies optics, recycles optics, and performs the materials science and technology to advance optics and optical materials for high-power and high-energy lasers for a variety of missions. The organization is a core capability at LLNL. We have a strong partnership with many optical fabricators, universities and national laboratories to accomplish our goals. The organization has a long history of performing fundamental optical materials science, developing them into useful technologies, and transferring them into production both on-site and off-site. We are successfully continuing this same strategy today.

Optical-fiber-connected 300-GHz FM-CW radar system

NASA Astrophysics Data System (ADS)

Kanno, Atsushi; Sekine, Norihiko; Kasamatsu, Akifumi; Yamamoto, Naokatsu; Kawanishi, Tetsuya

2017-05-01

300-GHz frequency-modulated continuous-wave (FM-CW) radar system operated by radio over fiber technologies is configured and demonstrated. Centralized signal generator, which is based on an optical frequency comb generation, provides high-precise FM-CW radar signal. The optical signal is easy to be transported to radar heads through an optical fiber network. Optical-modulator-based optical frequency comb generator is utilized as an optical frequency multiplier from a microwave signal to a 300-GHz terahertz signal by an optical modulation technique. In the study, we discuss the configuration of the network, signal generator and remote radar head for terahertz-wave multi-static radar system.

Optical registration of spaceborne low light remote sensing camera

NASA Astrophysics Data System (ADS)

Li, Chong-yang; Hao, Yan-hui; Xu, Peng-mei; Wang, Dong-jie; Ma, Li-na; Zhao, Ying-long

2018-02-01

For the high precision requirement of spaceborne low light remote sensing camera optical registration, optical registration of dual channel for CCD and EMCCD is achieved by the high magnification optical registration system. System integration optical registration and accuracy of optical registration scheme for spaceborne low light remote sensing camera with short focal depth and wide field of view is proposed in this paper. It also includes analysis of parallel misalignment of CCD and accuracy of optical registration. Actual registration results show that imaging clearly, MTF and accuracy of optical registration meet requirements, it provide important guarantee to get high quality image data in orbit.

3D two-photon lithographic microfabrication system

DOEpatents

Kim, Daekeun [Cambridge, MA; So, Peter T. C. [Boston, MA

2011-03-08

An imaging system is provided that includes a optical pulse generator for providing an optical pulse having a spectral bandwidth and includes monochromatic waves having different wavelengths. A dispersive element receives a second optical pulse associated with the optical pulse and disperses the second optical pulse at different angles on the surface of the dispersive element depending on wavelength. One or more focal elements receives the dispersed second optical pulse produced on the dispersive element. The one or more focal element recombine the dispersed second optical pulse at a focal plane on a specimen where the width of the optical pulse is restored at the focal plane.

Optics & Materials Science & Technology (OMST) Organization at LLNL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suratwala,; Tayyab,; Nguyen, Hoang

The Optics and Materials Science & Technology (OMST) organization at Lawrence Livermore National Laboratory (LLNL) supplies optics, recycles optics, and performs the materials science and technology to advance optics and optical materials for high-power and high-energy lasers for a variety of missions. The organization is a core capability at LLNL. We have a strong partnership with many optical fabricators, universities and national laboratories to accomplish our goals. The organization has a long history of performing fundamental optical materials science, developing them into useful technologies, and transferring them into production both on-site and off-site. We are successfully continuing this same strategymore » today.« less

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor)

2000-01-01

A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

1999-01-01

A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

The research and development of the adaptive optics in ophthalmology

NASA Astrophysics Data System (ADS)

Wu, Chuhan; Zhang, Xiaofang; Chen, Weilin

2015-08-01

Recently the combination of adaptive optics and ophthalmology has made great progress and become highly effective. The retina disease is diagnosed by retina imaging technique based on scanning optical system, so the scanning of eye requires optical system characterized by great ability of anti-moving and optical aberration correction. The adaptive optics possesses high level of adaptability and is available for real time imaging, which meets the requirement of medical retina detection with accurate images. Now the Scanning Laser Ophthalmoscope and the Optical Coherence Tomography are widely used, which are the core techniques in the area of medical retina detection. Based on the above techniques, in China, a few adaptive optics systems used for eye medical scanning have been designed by some researchers from The Institute of Optics And Electronics of CAS(The Chinese Academy of Sciences); some foreign research institutions have adopted other methods to eliminate the interference of eye moving and optical aberration; there are many relevant patents at home and abroad. In this paper, the principles and relevant technique details of the Scanning Laser Ophthalmoscope and the Optical Coherence Tomography are described. And the recent development and progress of adaptive optics in the field of eye retina imaging are analyzed and summarized.

Phase change material based tunable reflectarray for free-space optical inter/intra chip interconnects.

PubMed

Zou, Longfang; Cryan, Martin; Klemm, Maciej

2014-10-06

The concept of phase change material (PCM) based optical antennas and antenna arrays is proposed for dynamic beam shaping and steering utilized in free-space optical inter/intra chip interconnects. The essence of this concept lies in the fact that the behaviour of PCM based optical antennas will change due to the different optical properties of the amorphous and crystalline state of the PCM. By engineering optical antennas or antenna arrays, it is feasible to design dynamic optical links in a desired manner. In order to illustrate this concept, a PCM based tunable reflectarray is proposed for a scenario of a dynamic optical link between a source and two receivers. The designed reflectarray is able to switch the optical link between two receivers by switching the two states of the PCM. Two types of antennas are employed in the proposed tunable reflectarray to achieve full control of the wavefront of the reflected beam. Numerical studies show the expected binary beam steering at the optical communication wavelength of 1.55 μm. This study suggests a new research area of PCM based optical antennas and antenna arrays for dynamic optical switching and routing.

Peptide Integrated Optics.

PubMed

Handelman, Amir; Lapshina, Nadezda; Apter, Boris; Rosenman, Gil

2018-02-01

Bio-nanophotonics is a wide field in which advanced optical materials, biomedicine, fundamental optics, and nanotechnology are combined and result in the development of biomedical optical chips. Silk fibers or synthetic bioabsorbable polymers are the main light-guiding components. In this work, an advanced concept of integrated bio-optics is proposed, which is based on bioinspired peptide optical materials exhibiting wide optical transparency, nonlinear and electrooptical properties, and effective passive and active waveguiding. Developed new technology combining bottom-up controlled deposition of peptide planar wafers of a large area and top-down focus ion beam lithography provides direct fabrication of peptide optical integrated circuits. Finding a deep modification of peptide optical properties by reconformation of biological secondary structure from native phase to β-sheet architecture is followed by the appearance of visible fluorescence and unexpected transition from a native passive optical waveguiding to an active one. Original biocompatibility, switchable regimes of waveguiding, and multifunctional nonlinear optical properties make these new peptide planar optical materials attractive for application in emerging technology of lab-on-biochips, combining biomedical photonic and electronic circuits toward medical diagnosis, light-activated therapy, and health monitoring. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical characteristics of waste stabilization ponds: recommendations for monitoring.

PubMed

Davies-Colley, R J; Craggs, R J; Park, J; Nagels, J W

2005-01-01

The optical character of waste stabilization ponds (WSPs) is of concern for several reasons. Algal photosynthesis, which produces oxygen for waste oxidation in WSPs, is influenced by attenuation of sunlight in ponds. Disinfection in WSPs is influenced by optical characteristics because solar UV exposure usually dominates inactivation. The optical nature of WSPs effluent also affects assimilation by receiving waters. Despite the importance of light behaviour in WSPs, few studies have been made of their optical characteristics. We discuss simple optical measures suitable for routine monitoring of WSPs (including at sites remote from laboratories): optical density of filtrates - an index of dissolved coloured organic (humic) matter, visual clarity - to provide an estimate of the beam attenuation coefficient (a fundamental quantity needed for optical modelling) colour (hue) - as an indicator of general WSP 'condition' and irradiance attenuation quantifying depth of light penetration. The value of optical characterisation of WSPs is illustrated with reference to optical data for WSPs in NZ (including high-rate algal ponds) treating dairy cattle wastewater versus domestic sewage. We encourage increased research on optical characteristics of WSPs and the incorporation of optical measures in monitoring and modelling of WSP performance.

Study of 3D printing method for GRIN micro-optics devices

NASA Astrophysics Data System (ADS)

Wang, P. J.; Yeh, J. A.; Hsu, W. Y.; Cheng, Y. C.; Lee, W.; Wu, N. H.; Wu, C. Y.

2016-03-01

Conventional optical elements are based on either refractive or reflective optics theory to fulfill the design specifications via optics performance data. In refractive optical lenses, the refractive index of materials and radius of curvature of element surfaces determine the optical power and wavefront aberrations so that optical performance can be further optimized iteratively. Although gradient index (GRIN) phenomenon in optical materials is well studied for more than a half century, the optics theory in lens design via GRIN materials is still yet to be comprehensively investigated before realistic GRIN lenses are manufactured. In this paper, 3D printing method for manufacture of micro-optics devices with special features has been studied based on methods reported in the literatures. Due to the additive nature of the method, GRIN lenses in micro-optics devices seem to be readily achievable if a design methodology is available. First, derivation of ray-tracing formulae is introduced for all possible structures in GRIN lenses. Optics simulation program is employed for characterization of GRIN lenses with performance data given by aberration coefficients in Zernike polynomial. Finally, a proposed structure of 3D printing machine is described with conceptual illustration.

Optical elements design of optical pick-up with characteristics of read-out spot for high density optical storage

NASA Astrophysics Data System (ADS)

Li, Lihua; Ma, Jianshe; Liu, Lin; Pan, Longfa; Zhang, Jianyong; Lu, Junhui

2005-09-01

It is well known that the optical pick-up (OPU) plays a very important role in optical storage system. And the quality of OPU can be measured by the characteristics of OPU read-out spot for high density optical storage. Therefore this paper mainly designs an OPU model for high density optical storage to study the characteristics of OPU read-out spot. Firstly it analyses the optical read-out principle in OPU and contrives an optical read-out system based on the hereinbefore theory. In this step it chiefly designs the grating, splitter, collimator lens and objective lens. Secondly based on the aberrations analysis and theory involved by the splitter, the collimator lens and the optical lens, the paper uses the software CODE V to calculate the aberrations and to optimize the optical read-out system. Then the author can receive an ideal OPU read-out spot for high density optical storage and obtain the characteristics of the ideal OPU read-out spot. At the same time this paper analyses some influence factors which can directly affect the characteristics of the OPU read-out spot. Thirdly according to the up data the author practically manufactures a real optical pick-up to validate the hereinbefore designed optical read-out system. And it uses the Optical Spot Analyzer to get the image of the read-out spot. Comparing the ideal image to the actual image of the designed optical read-out system, the author finds out that the upwards analyses and design is suitable for high density storage and can be used in the actual production. And the author also receives the conclusion that the mostly influences on characteristics of OPU read-out spot for high density optical storage factors is not only the process of designing the grating, splitter, collimator lens and objective lens, but also the assembling work precision

Initial Performance Evaluation of Optical Fibers and Sensors Under High-Energy Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Palmer, Matthew E.; Slusher, David; Fielder, Robert S.

2006-01-01

In this paper, recent work on the performance of optical fiber, fiber optic sensors, and fiber optic connectors under the influence of a high-energy electron beam is presented. Electron beam irradiation is relevant for the Jupiter Icy Moons Orbiter (JIMO) mission due to the high electron radiation environment surrounding Jupiter. As an initial feasibility test, selected optical fiber components were exposed to dose levels relevant to the Jupiter environment. Three separate fiber types were used: one series consisted of pure silica core fiber, two other series consisted of different levels of Germania-doped fiber. Additionally, a series of fused silica Extrinsic Fabry-Perot Interferometer (EFPI)-based fiber optic sensors and two different types of fiber optic connectors were tested. Two types of fiber coatings were evaluated: acrylate and polyimide. All samples were exposed to three different dose levels: 2 MRad, 20 MRad, and 50 MRad. Optical loss measurements were made on the optical fiber spools as a function of wavelength between 750 and 1750nm at periodic intervals up to 75 hrs after exposure. Attenuation is minimal and wavelength-dependent. Fiber optic sensors were evaluated using a standard EFPI sensor readout and diagnostic system. Optical connectors and optical fiber coatings were visually inspected for degradation. Additionally, tensile testing and minimum bend radius testing was conducted on the fibers. Initial loss measurements indicate a low-level of induced optical attenuation in the fiber which recovers with time. The fiber optic sensors exhibited no observable degradation after exposure. The optical fiber connectors and coatings also showed no observable degradation. In addition to harsh environment survivability, fiber optic sensors offer a number of intrinsic advantages for space nuclear power applications including extremely low mass, immunity to electromagnetic interference, self diagnostics / prognostics, and smart sensor capability. Deploying fiber optic sensors on future space exploration missions would provide a substantial improvement in spacecraft instrumentation.

All-Optical Fibre Networks For Coal Mines

NASA Astrophysics Data System (ADS)

Zientkiewicz, Jacek K.

1987-09-01

A topic of the paper is fiber-optic integrated network (FOIN) suited to the most hostile environments existing in coal mines. The use of optical fibres for transmission of mine instrumentation data offers the prospects of improved safety and immunity to electromagnetic interference (EMI). The feasibility of optically powered sensors has opened up new opportunities for research into optical signal processing architectures. This article discusses a new fibre-optic sensor network involving a time domain multiplexing(TDM)scheme and optical signal processing techniques. The pros and cons of different FOIN topologies with respect to coal mine applications are considered. The emphasis has been placed on a recently developed all-optical fibre network using spread spectrum code division multiple access (COMA) techniques. The all-optical networks have applications in explosive environments where electrical isolation is required.

Techniques for writing and reading data on an optical disk which include formation of holographic optical gratings in plural locations on the optical disk

NASA Technical Reports Server (NTRS)

Liu, Tsuen-Hsi (Inventor); Psaltis, Demetri (Inventor); Mok, Fai H. (Inventor); Zhou, Gan (Inventor)

2005-01-01

An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created, and subsequently detected, at plural locations within the disk by an electro-optical head. Creation and detection of holographic gratings with variable diffraction efficiency is possible with the electro-optical head. Multiple holographic gratings can also be created at each one of the plural locations via a beam of light which has a different wavelength or point of focus. These data elements can be read by the electro-optical head using a beam of light sequentially varied in wavelength or point of focus to correspond to the multiple holographic gratings to be recorded.

Review of optical freeform surface representation technique and its application

NASA Astrophysics Data System (ADS)

Ye, Jingfei; Chen, Lu; Li, Xinhua; Yuan, Qun; Gao, Zhishan

2017-11-01

Modern advanced manufacturing and testing technologies allow the application of freeform optical elements. Compared with traditional spherical surfaces, an optical freeform surface has more degrees of freedom in optical design and provides substantially improved imaging performance. In freeform optics, the representation technique of a freeform surface has been a fundamental and key research topic in recent years. Moreover, it has a close relationship with other aspects of the design, manufacturing, testing, and application of optical freeform surfaces. Improvements in freeform surface representation techniques will make a significant contribution to the further development of freeform optics. We present a detailed review of the different types of optical freeform surface representation techniques and their applications and discuss their properties and differences. Additionally, we analyze the future trends of optical freeform surface representation techniques.

High bandwidth optical mount

DOEpatents

Bender, Donald A.; Kuklo, Thomas

1994-01-01

An optical mount, which directs a laser beam to a point by controlling the position of a light-transmitting optic, is stiffened so that a lowest resonant frequency of the mount is approximately one kilohertz. The optical mount, which is cylindrically-shaped, positions the optic by individually moving a plurality of carriages which are positioned longitudinally within a sidewall of the mount. The optical mount is stiffened by allowing each carriage, which is attached to the optic, to move only in a direction which is substantially parallel to a center axis of the optic. The carriage is limited to an axial movement by flexures or linear bearings which connect the carriage to the mount. The carriage is moved by a piezoelectric transducer. By limiting the carriage to axial movement, the optic can be kinematically clamped to a carriage.

Analysis of the influence of manufacturing and alignment related errors on an optical tweezer system

NASA Astrophysics Data System (ADS)

Kampmann, R.; Sinzinger, S.

2014-12-01

In this work we present the design process as well as experimental results of an optical system for trapping particles in air. For positioning applications of micro-sized objects onto a glass wafer we developed a highly efficient optical tweezer. The focus of this paper is the iterative design process where we combine classical optics design software with a ray optics based force simulation tool. Thus we can find the best compromise which matches the optical systems restrictions with stable trapping conditions. Furthermore we analyze the influence of manufacturing related tolerances and errors in the alignment process of the optical elements on the optical forces. We present the design procedure for the necessary optical elements as well as experimental results for the aligned system.