Management of Localized Prostate Cancer in Men With Human Immunodeficiency Virus: Analysis of a Large Retrospective Cohort

INTRODUCTION

We aimed to characterize the clinicopathological characteristics and outcomes of HIV-positive patients with clinically localized, prostate cancer (PCa).

METHODS

A retrospective study was conducted of HIV-positive patients from a single institution with elevated PSA and diagnosis of PCa by biopsy. PCa features, HIV characteristics, treatment type, toxicities, and outcomes were analyzed by descriptive statistics. Kaplan-Meier analysis was used to determine progression-free survival (PFS).

RESULTS

Seventy-nine HIV-positive patients were included with a median age at PCa diagnosis of 61 years-old and median duration from HIV infection to PCa diagnosis of 21 years. The median PSA level at diagnosis and Gleason Score was 6.85 ng/mL and 7, respectively. The 5-year PFS was 82.5% with the lowest survival observed in patients treated with radical prostatectomy (RP) + radiation therapy (RT), followed by cryosurgery (CS). There were no reports of PCa-specific deaths, and the 5-year overall survival was 97.5%. CD4 count declined post-treatment in pooled treatment groups that included RT (P = .02).

CONCLUSION

We present the characteristics and outcomes of the largest cohort of HIV-positive men with prostate cancer in published literature. RP and RT ± ADT is well-tolerated in HIV-positive patients with PCa as seen by the adequate biochemical control and mild toxicity. CS resulted in worse PFS compared to alternative treatments for patients within the same PCa risk group. A decline in CD4 counts was observed in patients treated RT, and further studies are needed to investigate this relationship. Our findings support the use of standard-of-care treatment for localized PCa in HIV-positive patients.

Utility of the "All of Us" Database for Radiation Oncology Research

PURPOSE/OBJECTIVE(S)

We provide an overview the All of Us Research Program, a National Institutes of Health funded research database, and report on the utility of this database for Radiation Oncology research.

MATERIALS/METHODS

The All of Us Research Program aims to create a large and diverse health database with participants from across the US. Patients consent to join the database and agree to share electronic health records, complete surveys, provide physical measurements, and donate at least one biospecimen. In this observational study, we used the public data browser feature of the All of Us Dataset to evaluate utility for future radiation oncology research. Within the database, we report on the number of cases of common cancers in the US, using ICD10 codes, and also the number of patients treated with common radiotherapy procedures, using CPT4 codes. We then qualitatively report on additional data of interest. Of note, public patient counts in All of Us is rounded to the nearest interval of 20. Additional tiers of data access exist, including individual level data, which were not used in this survey of public data.

RESULTS

The database includes 372,380 participants, of which 46,380 patients have a diagnosis of cancer. Within the identified top 10 cancers according to ACS, there were a total of 26,540 primary malignant cancers. The most common type of cancers were breast cancer (ICD10 - c50 [n = 6,960]), Prostate (ICD10 - c61 [n = 4,500]), Non-Hodgkin lymphoma (ICD10 - c85 [n = 2860]), Lung & bronchus (ICD10 - c34 [n = 2000]), Colon (ICD10 - c18 [n = 1940]), Melanoma of the skin (ICD10 - c43 [n = 1740]), Thyroid(ICD10 - c73 [n = 1720]), Kidney (ICD10 - c64 [n = 1300]), Urinary bladder (ICD10 - c67 [n = 1140]). The most common radiation therapy procedures were Computerized Tomography simulation (CPT - 77290 [n = 4,040]), Intensity Modulated Radiation Therapy (CPT - 77386 [n = 780]), 3D conformal radiation therapy (CPT - 77412 [n = 1,720]), Stereotactic Body Radiation Therapy (CPT - 77373 [n = 400]), Brachytherapy (CPT - 77770- 77772 [n = 240]), and Proton Therapy (CPT - 77520-77525 [n = 140]). Qualitatively, other data within All of Us include labs values, drug exposures, comorbidities, other procedures, physical measurements, and wearable biometrics (Fitbit) data. Genomic data typically includes germline testing using whole genome sequencing or genotyping array. Patient surveys include data on personal medical history, family health history, lifestyle, social determinants of health, COVID19 experience, and overall health. Potential outcome variables of interest to oncology research in the database include survival, cause of death, additional procedures or diagnoses after cancer treatment, and quality of life metrics derived from the survey instruments.

CONCLUSION

The All Of Us Research Database includes a large number of cancer cases, of which a substantial number received radiotherapy. Future work will focus on focused hypothesis-driven research questions.

Focal Boosted IMRT Treatment of Prostate Cancer to 84 Gy in 28 Fractions: Preliminary Clinical Outcomes and Dosimetry

PURPOSE/OBJECTIVE(S)

The FLAME trial reported that focal boosting of prostate tumor to 95 Gy in 35 fractions improves biochemical control. However, this treatment is not commonly used in the United States. We investigated a focally boosted treatment of 84 Gy in 28 fractions (EQD2 108 Gy, BED 252 Gy).

MATERIALS/METHODS

Between 2019-2022, men with unfavorable intermediate risk (uIR) and high risk (HR) prostate cancer were enrolled on a prospective registry and received a novel IMRT regimen. The dose levels were 84 Gy to the gross tumor volume (GTV) as defined on mpMRI (T2W and ADC) with no added margin, 70 Gy to the prostate and proximal seminal vesicles, and optional 50.4 Gy to elective pelvic lymph nodes (all 28 fractions). Patients received fiducial markers and hydrogel spacer. The treatment planning goal was to cover 95% of the GTV at 84 Gy, and also meet the target and normal tissue dosimetry criteria of the hypofractionated treatment arm of NRG-GU005. VMAT was used for treatment delivery. ADT was given at the discretion of the treating physician.

RESULTS

A total of 20 men were included in the study, 2 (10%) uIR and 18 (90%) HR. 9 (45%) tumors were GS 7, 7 (35%) were GS 8, and 4 (20%) were GS 9. There were 13 (65%) stage cT1, 4 (20%) cT2 and 3 (15%) cT3. One (5%) patient received short term ADT, 18 (95%) long term ADT, and 1 (5%) refused ADT. 18 (90%) men received elective nodal radiation. The mean baseline PSA was 25.1 (range 4.2-73.4). The median baseline IPSS score was 11.1 (IQR 4.5-12), and 4 patients had severe baseline urinary symptoms (IPSS ≥20). The mean baseline prostate volume was 57.4 cc (range 26.8-198.3). The mean volume of the 84 Gy boost target was 7.1 cc (range 2.3-15.0) and the mean proportion of the prostate boosted was 14.8% (range 2% - 47%). There were 10 (50%) men with 1 boost target, 6 (30%) with two, 3 (15%) with three, and 1 (5%) had 4 boost targets. Targets were located in peripheral zone (85%), transition zone (30%), and central zone (5%). Patients met all per-protocol normal tissue criteria of NRG-GU005, except for bladder D0.03cc. The mean±SD (Gy) rectum D15%, D25%, and D30% were 51±5, 45±5, 42±4. The mean±SD (Gy) bladder D0.03cc, D30%, D50% were 79±4, 50±8, 38±10. At a median follow up time of 21.3 months (range 7.1-38.2), no patients have developed biochemical progression, local recurrence, distant progression, or death from prostate cancer. One patient died at 18 months from metastatic colorectal cancer, unrelated to prostate cancer treatment. Acute grade 1-2 GU toxicity occurred in 13 (65%) patients, and acute grade 1-2 GI toxicity occurred in 4 (20%) patients. No patients developed grade 3+ acute or late GU or GI toxicity. Two patients required temporary foley catheter for obstruction during RT, and both had IPSS >20 at baseline. The patient who refused ADT had a PSA bounce of magnitude 2.2 ng/mL at 14 months, PSA values declined without additional treatment.

CONCLUSION

A novel 28-fraction focal boosted IMRT treatment is feasible and has an acceptable early toxicity profile. Oncologic results are promising but require longer follow up.

Prediction of Progression After Cervix Cancer Radiotherapy Using a Machine-Learning Model on Pre-Treatment MRI

PURPOSE/OBJECTIVE(S)

MRI may be useful to identify women with cervical cancer at high risk of disease progression to test strategies of treatment intensification. The purpose of this study was to determine the value of a machine-learning model built on pre-treatment MRI for prediction of risk of progression after radiation therapy.

MATERIALS/METHODS

MagneticResonance Imaging (MRI) data for women with cervical cancer was collected from The Cancer Genome Atlas Cervical Squamous Cell Carcinoma and Endocervical Adenocarcinoma Collection (TCGA-CESC) on the Cancer Imaging Archive (TCIA), which reported clinical, treatment, and imaging data from a single institution. 27 patients who had received radiation for cervical cancer were selected for input into a custom 3-D Residual Neural Network (ResNet) model with added custom layers specific to DICOM data in tensorflow python package. One T2 MRI per patient was used to predict recurrence free survival after radiation treatment, where patients were predicted to be "high risk" or "low risk" for disease recurrence as the output of the model. All slices of the T2 MRI were used. The model was validated using five-fold cross validation; 80% of the data was used to train each fold and 20% was used for testing. Final model statistical significance was confirmed through shuffle test at the p < 0.01 level. The clinical outcomes of patients and the model's "low-risk" and "high-risk" prediction were compared.

RESULTS

There were 27 patients in the study with mean age of 51 years (range 29-79). 20 patients had squamous cell carcinoma and 7 patients had adenocarcinoma. The stage breakdown consisted of 9 women IB, 2 IIA, 9 IIB, 2 IIIA, 2 IIIB, and 3 stage IV. 10 women were treated with radiation alone and 17 with chemo-radiation. 5 women received surgery in addition to radiation or chemoradiation. 21 patients received brachytherapy. Median follow-up of patients was 29 months (range 3-64). The model predicted 7 patients as "high risk" for recurrence; all 7 developed a recurrence during follow up. None of the 20 patients predicted to be "low risk" developed disease recurrence. Among all patients in the study, the two-year progression free survival (PFS) was 82.0%. Patients identified as "low risk" and "high risk" by model had two-year PFS of 100% and 43%, respectively. Among patients with recurrence, 3 developed local recurrence and 4 developed distant metastases. The ResNet model achieved cross-validated accuracy of 92% for prediction of progression-free survival (p<0.01).

CONCLUSION

A 3-D ResNet machine-learning model using pretreatment MRI image data can accurately predict clinical outcomes for cervical cancer following radiation therapy. Future work to confirm generalizability should focus on validation with a larger clinical dataset.

Interplay of Immunosuppression and Immunotherapy Among Patients With Cancer and COVID-19

Importance

Cytokine storm due to COVID-19 can cause high morbidity and mortality and may be more common in patients with cancer treated with immunotherapy (IO) due to immune system activation.

Objective

To determine the association of baseline immunosuppression and/or IO-based therapies with COVID-19 severity and cytokine storm in patients with cancer.

Design, Setting, and Participants

This registry-based retrospective cohort study included 12 046 patients reported to the COVID-19 and Cancer Consortium (CCC19) registry from March 2020 to May 2022. The CCC19 registry is a centralized international multi-institutional registry of patients with COVID-19 with a current or past diagnosis of cancer. Records analyzed included patients with active or previous cancer who had a laboratory-confirmed infection with SARS-CoV-2 by polymerase chain reaction and/or serologic findings.

Exposures

Immunosuppression due to therapy; systemic anticancer therapy (IO or non-IO).

Main Outcomes and Measures

The primary outcome was a 5-level ordinal scale of COVID-19 severity: no complications; hospitalized without requiring oxygen; hospitalized and required oxygen; intensive care unit admission and/or mechanical ventilation; death. The secondary outcome was the occurrence of cytokine storm.

Results

The median age of the entire cohort was 65 years (interquartile range [IQR], 54-74) years and 6359 patients were female (52.8%) and 6598 (54.8%) were non-Hispanic White. A total of 599 (5.0%) patients received IO, whereas 4327 (35.9%) received non-IO systemic anticancer therapies, and 7120 (59.1%) did not receive any antineoplastic regimen within 3 months prior to COVID-19 diagnosis. Although no difference in COVID-19 severity and cytokine storm was found in the IO group compared with the untreated group in the total cohort (adjusted odds ratio [aOR], 0.80; 95% CI, 0.56-1.13, and aOR, 0.89; 95% CI, 0.41-1.93, respectively), patients with baseline immunosuppression treated with IO (vs untreated) had worse COVID-19 severity and cytokine storm (aOR, 3.33; 95% CI, 1.38-8.01, and aOR, 4.41; 95% CI, 1.71-11.38, respectively). Patients with immunosuppression receiving non-IO therapies (vs untreated) also had worse COVID-19 severity (aOR, 1.79; 95% CI, 1.36-2.35) and cytokine storm (aOR, 2.32; 95% CI, 1.42-3.79).

Conclusions and Relevance

This cohort study found that in patients with cancer and COVID-19, administration of systemic anticancer therapies, especially IO, in the context of baseline immunosuppression was associated with severe clinical outcomes and the development of cytokine storm.

Trial Registration

ClinicalTrials.gov Identifier: NCT04354701.

Prostate Cancer Outcomes in Patients Living with HIV/AIDS Treated with Radiation Therapy: A Systematic Review

Purpose

A consensus has not been reached regarding the treatment and outcomes of prostate cancer (PCa) in people living with HIV/AIDS (PLWHA). This systematic review aims to summarize the evidence on the management of PCa with radiation therapy (RT) in PLWHA diagnosed with PCa.

Methods and Materials

Searches were conducted in the PubMed, Cochrane Library, and Scopus databases during September 2021 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Articles reporting on outcomes of PLWHA treated for PCa with definitive RT were sought for inclusion.

Results

A total of 9 studies with 187 patients with HIV who received diagnoses of PCa met inclusion criteria. The duration of HIV infection to PCa diagnosis ranged from 8.5 to 18.6 years with 69% to 100% of patients on highly active antiretroviral therapy at the time of diagnosis. Patients’ prostate-specific antigen levels ranged from 8 to 82 ng/mL. The majority of patients (59%) were treated with external beam RT, followed by brachytherapy (20.5%). The 4- or 5-year biochemical failure–free rate was reported to be between 87% and 97% in 3 studies, and 2 studies reported an 84% to 97% 5-year cancer-specific survival. Using Common Terminology Criteria for Adverse Events criteria, 3 studies reported toxicities and grade 3 toxicity was observed in only 2 patients.

Conclusions

RT is efficacious and well tolerated in PLWHA as supported by the comparable biochemical control, clinical outcome, and mortality to the general population as well as by the mild reports of radiotoxicity. There is mixed evidence regarding the effect of RT on CD4 count and viral load, and further studies are needed to better understand this relationship. These findings support the use of definitive RT in PLWHA with PCa.

Incidence, Mortality, and Treatment Patterns of Synchronous Lower Genital Tract Squamous Cell Carcinoma

OBJECTIVE

The aim of the study was to define the incidence, prognosis, and treatment patterns associated with synchronous lower genital tract squamous cell carcinoma (LGTSCC) among women diagnosed with any LGTSCC.

MATERIALS AND METHODS

Surveillance, Epidemiology, and End Results (SEER) database patients diagnosed with synchronous cervical, vaginal, vulvar, and/or anal SCC from 2000 to 2016 were included. Incidence and mortality were evaluated using Kaplan-Meier curves. Multivariable Cox proportional hazards regression was used to identify treatment patterns, risk factors, and mortality associated with LGTSCC.

RESULTS

Among 15,424 women with LGTSCC, 138 had synchronous LGTSCC (0.89%). Vulvar and vaginal SCC was the most common combination (49.3%), and cervical with anal SCC was the least common (1.4%). Only one patient had 3 or more primary LGTSCC. Synchronous LGTSCC was independently associated with higher mortality compared with single-site LGTSCC (adjusted hazards ratio [aHR] = 1.67; p < .001). Synchronous LGTSCC was significantly associated with older age (63 vs. 58 years, p < .001) and lower stage (adjusted odds ratio [aOR] = 0.38; p < .001) and grade of disease (aOR = 0.32; p < .001). Patients with synchronous LGTSCC were more likely to receive radiation (aOR = 1.74; p = .005) and were more likely to receive adjuvant radiation after primary surgical resection compared with single-site LGTSCC (aOR = 1.88; p = .007). Receipt of any treatment including radiation (aHR = 0.85; p < .001), chemotherapy (aHR = 0.50; p < .001), and surgery (aHR = 0.70; p < .001) was independently associated with decreased mortality hazard.

CONCLUSIONS

Synchronous LGTSCC is rare but is associated with increased mortality and higher rates of adjuvant radiation compared with single-site LGTSCC despite lower stage and grade at diagnosis. More research is needed to define optimal therapy for these patients.

A feasibility study to evaluate early treatment response of brain metastases one week after stereotactic radiosurgery using perfusion weighted imaging

Background

To explore if early perfusion-weighted magnetic resonance imaging (PWI) may be a promising imaging biomarker to predict local recurrence (LR) of brain metastases after stereotactic radiosurgery (SRS).

Methods

This is a prospective pilot study of adult brain metastasis patients who were treated with SRS and imaged with PWI before and 1 week later. Relative cerebral blood volume (rCBV) parameter maps were calculated by normalizing to the mean value of the contralateral white matter on PWI. Cox regression was conducted to explore factors associated with time to LR, with Bonferroni adjusted p<0.0006 for multiple testing correction. LR rates were estimated with the Kaplan-Meier method and compared using the log-rank test.

Results

Twenty-three patients were enrolled from 2013 through 2016, with 22 evaluable lesions from 16 patients. After a median follow-up of 13.1 months (range: 3.0–53.7), 5 lesions (21%) developed LR after a median of 3.4 months (range: 2.3–5.7). On univariable analysis, larger tumor volume (HR 1.48, 95% CI 1.02–2.15, p = 0.04), lower SRS dose (HR 0.45, 95% CI 0.21–0.97, p = 0.04), and higher rCBV at week 1 (HR 1.07, 95% CI 1.003–1.14, p = 0.04) had borderline association with shorter time to LR. Tumors >2.0cm³ had significantly higher LR than if ≤2.0cm³: 54% vs 0% at 1 year, respectively, p = 0.008. A future study to confirm the association of early PWI and LR of the high-risk cohort of lesions >2.0cm³ is estimated to require 258 patients.

Conclusions

PWI at week 1 after SRS may have borderline association with LR. Tumors <2.0cm³ have low risk of LR after SRS and may be low-yield for predictive biomarker studies. Information regarding sample size and potential challenges for future imaging biomarker studies may be gleaned from this pilot study.

Machine Learning Detects Pattern of Differences in Functional Magnetic Resonance Imaging (fMRI) Data between Chronic Fatigue Syndrome (CFS) and Gulf War Illness (GWI)

BACKGROUND

Gulf War Illness (GWI) and Chronic Fatigue Syndrome (CFS) are two debilitating disorders that share similar symptoms of chronic pain, fatigue, and exertional exhaustion after exercise. Many physicians continue to believe that both are psychosomatic disorders and to date no underlying etiology has been discovered. As such, uncovering objective biomarkers is important to lend credibility to criteria for diagnosis and to help differentiate the two disorders.

METHODS

We assessed cognitive differences in 80 subjects with GWI and 38 with CFS by comparing corresponding fMRI scans during 2-back working memory tasks before and after exercise to model brain activation during normal activity and after exertional exhaustion, respectively. Voxels were grouped by the count of total activity into the Automated Anatomical Labeling (AAL) atlas and used in an "ensemble" series of machine learning algorithms to assess if a multi-regional pattern of differences in the fMRI scans could be detected.

RESULTS

A K-Nearest Neighbor (70%/81%), Linear Support Vector Machine (SVM) (70%/77%), Decision Tree (82%/82%), Random Forest (77%/78%), AdaBoost (69%/81%), Naïve Bayes (74%/78%), Quadratic Discriminant Analysis (QDA) (73%/75%), Logistic Regression model (82%/82%), and Neural Net (76%/77%) were able to differentiate CFS from GWI before and after exercise with an average of 75% accuracy in predictions across all models before exercise and 79% after exercise. An iterative feature selection and removal process based on Recursive Feature Elimination (RFE) and Random Forest importance selected 30 regions before exercise and 33 regions after exercise that differentiated CFS from GWI across all models, and produced the ultimate best accuracies of 82% before exercise and 82% after exercise by Logistic Regression or Decision Tree by a single model, and 100% before and after exercise when selected by any six or more models. Differential activation on both days included the right anterior insula, left putamen, and bilateral orbital frontal, ventrolateral prefrontal cortex, superior, inferior, and precuneus (medial) parietal, and lateral temporal regions. Day 2 had the cerebellum, left supplementary motor area and bilateral pre- and post-central gyri. Changes between days included the right Rolandic operculum switching to the left on Day 2, and the bilateral midcingulum switching to the left anterior cingulum.

CONCLUSION

We concluded that CFS and GWI are significantly differentiable using a pattern of fMRI activity based on an ensemble machine learning model.

Radiologic Assessment of Groin Lymph Nodes in Pelvic Malignancies

INTRODUCTION

Metastatic involvement of groin nodes can alter radiation therapy planning for pelvic tumors. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) can identify nodal metastases; however, interpretation of PET/CT-positive nodes can be complicated by non-malignant processes. We evaluated quantitative metrics as methods to identify groin metastases in patients with pelvic tumors by comparison with standard subjective interpretive criteria, with pathology as the reference standard.

METHODS

We retrospectively identified patients with vulvar, vaginal, or anal cancers who underwent ¹⁸F-FDG PET/CT before pathologic evaluation of groin nodes between 2007 and 2017. Because patho-radiologic correlation was not possible for every node, one index node identified on imaging was selected for each groin. For each index node, standardized uptake value measurements, total lesion glycolysis, metabolic tumor volume, CT-based volume, and short and long axes were measured. Multivariate logistic regression was used to identify metrics predictive for pathologically positive groins and generate a probabilistic model. Area under the receiver-operating characteristic curves (AUCs) for the model were compared with clinical interpretation from the diagnostic report via a Wald's χ² test.

RESULTS

Of 55 patients identified for analysis, 75 groins had pathologic evaluation resulting in 75 index groin nodes for analysis with 35 groins pathologically positive for malignancy. Logistic regression identified mean standardized-uptake-value (50% threshold) and short-axis length as the most predictive imaging metrics for metastatic nodal involvement. The probabilistic model performed better at predicting pathologic involvement compared with standard clinical interpretation on analysis (AUC 0.91, 95% CI 0.84 to 0.97 vs 0.80, 95% CI 0.71 to 0.89; p<0.01).

DISCUSSION

Accuracy of ¹⁸F-FDG PET/CT for detecting groin nodal metastases in patients with pelvic tumors may be improved with the use of quantitative metrics. Improving prediction of nodal metastases can aid with appropriate selection of patients for pathologic node evaluation and guide radiation volumes and doses.

Impact of concurrent versus adjuvant chemotherapy on the severity and duration of lymphopenia in glioma patients treated with radiation therapy

Prolonged severe lymphopenia has been shown to persist beyond a year in glioma patients after radiation therapy (RT) with concurrent and adjuvant chemotherapy. This study examines the differential impact of concurrent versus adjuvant chemotherapy on lymphopenia after RT. WHO grade II-III glioma patients who received RT with concurrent and/or adjuvant chemotherapy from 2007 to 2016 were retrospectively analyzed. Concurrent chemotherapy was temozolomide (TMZ), and adjuvant chemotherapy was either TMZ or procarbazine/lomustine/vincristine (PCV). Absolute lymphocyte count (ALC) was analyzed at baseline, 1.5, 3, 6, and 12 months after the start of RT. Univariable and multivariable logistic regression were used to identify the clinical variables in predicting acute or late lymphopenia. There were 151 patients with evaluable ALC: 91 received concurrent and adjuvant TMZ (CRT + ADJ), 32 received only concurrent TMZ (CRT), and 28 received only adjuvant TMZ or PCV (ADJ). There were 9 (10%) versus 6 (19%) versus 0 (0%) cases of grade 3 lymphopenia (ALC < 500/mm³) at 6 weeks and 4 (6%) versus 0 (0%) versus 3 (17%) cases at 12 months in CRT + ADJ, CRT and ADJ groups, respectively. On multivariable analyses, concurrent chemotherapy (odds ratio [OR] 72.3, p < 0.001), female sex (OR 10.8, p < 0.001), and older age (OR 1.06, p = 0.002) were the most significant predictors for any grade ≥ 1 lymphopenia (ALC < 1000/mm³) at 1.5 months. Older age (OR 1.08, p = 0.02) and duration of adjuvant chemotherapy (OR 1.19, p = 0.003) were significantly associated with grade ≥ 1 lymphopenia at 12 months. Thus, concurrent chemotherapy appears as the dominant contributor to the severity of acute lymphopenia after RT in WHO grade II-III glioma patients, and duration of adjuvant chemotherapy appears as the key factor to prolonged lymphopenia.

Patterns of care and outcomes of proton and eye plaque brachytherapy for uveal melanoma: Review of the National Cancer Database

PURPOSE

To examine national practice patterns and outcomes of eye plaque brachytherapy compared to proton external beam radiotherapy in the treatment of choroid melanoma.

METHODS AND MATERIALS

Demographic and clinical data for 1224 patients with choroid melanoma treated with either brachytherapy or proton beam therapy from 2004 to 2013 were obtained from the National Cancer Database. Logistic regression and propensity score matching was used to create a 1:1 matched cohort. Kaplan-Meier and Cox regression analyses were performed to evaluate survival in brachytherapy and proton groups.

RESULTS

Median followup was 37 and 29 months for brachytherapy and protons, respectively. Most patients were treated with brachytherapy (n = 996) vs. protons (n = 228). Proton patients came from more urban, affluent, and educated zip codes, and they were more likely to be treated at an academic center (all p < 0.004). In the propensity-score matched cohort, 2-year overall survival was 97% vs. 93%, and 5-year overall survival was 77% vs. 51% for brachytherapy and protons, respectively (p = 0.008). Multivariate Cox regression found older age (hazard ratio [HR] = 1.06, 95% confidence interval (CI) = 1.03-1.09), larger tumor diameter (12-18 mm, HR = 2.48, 95% CI = 1.40-4.42, >18 mm, HR = 6.41, 95% CI = 1.45-28.35), and protons (HR = 1.89, 95% CI = 1.06-3.37) were negative prognosticators of survival.

CONCLUSIONS

Patients selected for proton treatment have inferior survival outcomes compared to brachytherapy in this retrospective analysis. There may be unaccounted variables that influence survival, warranting further prospective studies.

Graphene Q-switched distributed feedback fiber lasers with narrow linewidth approaching the transform limit

A compact all-in-line graphene-based distributed feedback Bragg-grating fiber laser (GDFB-FL) with narrow linewidth of hundreds kHz is demonstrated and investigated in this study. Performing as an optical saturable absorber, graphene oscillates the initially kHz linewidth DFB-FL, and generates high-quality passively Q-switched pulses. Pumped with a 980 nm continuous-wave laser, the Q-switched GDFB-FL observes ~1 μs pulse durations, with pulse energies up to ~10 nJ and approaching the transform limit. The peak power is ~600 times higher than the original DFB-FL laser. By optimizing the cavity design and the graphene material, it is predicted that fast Q-switched pulses with more than MHz repetition rates and sub-100 ns pulse durations are achievable. Such transform-limited Q-switched GDFB-FLs with narrow linewidth of sub-MHz have long coherence length, good tunability, stability, compactness and robustness, with potential impact in optical coherent communications, metrology and sensing.

Quasi mode-locking of coherent feedback random fiber laser

Mode-locking is a milestone in the history of lasers that allows the generation of short light pulses and stabilization of lasers. This phenomenon is known to occur only in standard ordered lasers for long time and until recently it is found that it also occurs in disordered random lasers formed by nanoscale particles. Here, we report the realization of a so-called quasi mode-locking of coherent feedback random fiber laser which consists of a partially disordered linear cavity formed between a point reflector and a random distributed fiber Bragg grating array with an inserted graphene saturable absorber. We show that multi-groups of regular light pulses/sub-pulses with different repetition frequencies are generated within the quasi mode-locking regime through the so-called collective resonances phenomenon in such a random fiber laser. This work may provide a platform to study mode locking as well as pulse dynamic regulation of random lasing emission of coherent feedback disordered structures and pave the way to the development of novel multi-frequency pulse fiber lasers with potentially wide frequency tuning range.

Impact of Time Interval between Radiation and Free Autologous Breast Reconstruction

Background To evaluate whether the timing of surgery after radiation in autologous breast reconstruction affects major complications. Methods We performed a retrospective review of 454 free flaps (331 patients) for breast reconstruction at a single institution from 2003 to 2014. Charts were reviewed for age, BMI, laterality, flap type (TRAM, msTRAM, DIEP), surgeon, donor vessels (IMA, TD), chemotherapy, smoking, diabetes, hypertension, DVT, venous anastomoses, vein size, and time from radiation (none, < 12 months, or ≥ 12 months). The primary outcome of major complications was defined as partial/total flap loss, thrombosis, ischemia, or hematoma requiring return to the operating room. To identify independent predictors of major complications, a multivariate logistic regression was constructed. Alpha = 0.05 indicated significance in all tests. Results Average age was 47.4 ± 8.4. Free flaps consisted of msTRAM (41.1%), TRAM (29.6%), or DIEP (29.3%). The donor vessel was IMA in 66.9% of flaps or TD in 33.0% of patients with 90.7% using only one vein and 9.3% with two veins. The average IMA/TDV size was 2.5 cm ± 0.5. Preoperative radiation occurred in 31.2% of flaps. There were 54 flaps with at least one major complication (11.7%). On multivariate regression, only flap type (OR =4.04, p < .01) and vein size (OR = 0.13, p = 0.02) independently predicted major complications. Conclusion There was no significant difference in major complications between flaps who had reconstruction within 12 months and greater than 12 months after radiation. Only having a more muscle sparing technique or smaller vein size were independent risk factors for major complications.

Graphene based widely-tunable and singly-polarized pulse generation with random fiber lasers

Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse formation also demonstrates robust pulse-to-pulse stability and wide-wavelength operation due to the cavity-less feature. Such a graphene-based architecture not only provides a tunable pulsed random laser for fiber-optic sensing, speckle-free imaging, and laser-material processing, but also a new way for the non-random CW fiber lasers to generate widely tunable and singly-polarized pulses.

All optical mode controllable Er-doped random fiber laser with distributed Bragg gratings

An all-optical method to control the lasing modes of Er-doped random fiber lasers (RFLs) is proposed and demonstrated. In the RFL, an Er-doped fiber (EDF) recoded with randomly separated fiber Bragg gratings (FBG) is used as the gain medium and randomly distributed reflectors, as well as the controllable element. By combining random feedback of the FBG array and Fresnel feedback of a cleaved fiber end, multi-mode coherent random lasing is obtained with a threshold of 14 mW and power efficiency of 14.4%. Moreover, a laterally-injected control light is used to induce local gain perturbation, providing additional gain for certain random resonance modes. As a result, active mode selection of the RFL is realized by changing locations of the laser cavity that is exposed to the control light.

Stark effect induced microcavity polariton solitons

This paper proposes a way of generating polariton solitons (PSs) in a semiconductor microcavity using Stark effect as the trigger mechanism. A Stark pulse performing as the writing beam is used to excite non-resonant fluctuations of polariton, which finally evolves into bright PSs. It is found that a branch of PS solutions versus pump parameters could be found through optimizing parameters of the Stark pulse, and polarization of the generated PS is dependent on the writing beam.

Long-range and high-precision correlation optical time-domain reflectometry utilizing an all-fiber chaotic source

We propose a long range, high precision optical time domain reflectometry (OTDR) based on an all-fiber supercontinuum source. The source simply consists of a CW pump laser with moderate power and a section of fiber, which has a zero dispersion wavelength near the laser's central wavelength. Spectrum and time domain properties of the source are investigated, showing that the source has great capability in nonlinear optics, such as correlation OTDR due to its ultra-wide-band chaotic behavior, and mm-scale spatial resolution is demonstrated. Then we analyze the key factors limiting the operational range of such an OTDR, e. g., integral Rayleigh backscattering and the fiber loss, which degrades the optical signal to noise ratio at the receiver side, and then the guideline for counter-act such signal fading is discussed. Finally, we experimentally demonstrate a correlation OTDR with 100km sensing range and 8.2cm spatial resolution (1.2 million resolved points), as a verification of theoretical analysis.

Graphene enhanced evanescent field in microfiber multimode interferometer for highly sensitive gas sensing

Graphene based new physics phenomena are leading to a variety of stimulating graphene-based photonic devices. In this study, the enhancement of surface evanescent field by graphene cylindrical cladding is observed, for the first time, by using a graphene-coated microfiber multi-mode interferometer (GMMI). It is found theoretically and experimentally that the light transmitting in the fiber core is efficiently dragged by the graphene, hence significantly enhancing the evanescent fields, and subsequently improving the sensitivity of the hybrid waveguide. The experimental results for gas sensing verified the theoretical prediction, and ultra-high sensitivities of ~0.1 ppm for NH(3) gas detection and ~0.2 ppm for H(2)O vapor detection are achieved, which could be used for trace analysis. The enhancement of surface evanescent field induced by graphene may pave a new way for developing novel graphene-based all-fiber devices with compactness, low cost, and temperature immunity.

Graphene-based D-shaped fiber multicore mode interferometer for chemical gas sensing

In this Letter, a graphene-coated D-shaped fiber (GDF) chemical gas sensor is proposed and demonstrated. Taking advantage of both the graphene-induced evanescent field enhancement and the in-fiber multimode interferometer, the GDF shows very high sensitivity for polar gas molecule adsorptions. An extinction ratio of up to 28 dB within the free spectrum range of ~30  nm in the transmission spectrum is achieved. The maximum sensitivities for NH₃ and H₂O gas detections are ~0.04 and ~0.1  ppm, respectively. A hybrid sensing scheme with such compactness, high sensitivity, and online monitoring capabilities may pave the way for others to explore a series of graphene-based lab-on-fiber devices for biochemical sensing.

Ultra-long phase-sensitive OTDR with hybrid distributed amplification

A phase-sensitive optical time-domain reflectometry (Φ-OTDR) with 175 km sensing range and 25 m spatial resolution is demonstrated, using the combination of co-pumping second-order Raman amplification based on random fiber lasing, counter-pumping first-order Raman amplification, and counter-pumping Brillouin amplification. With elaborate arrangements, each pumping scheme is responsible for the signal amplification in one particular segment of all three. To the best of our knowledge, this is the first time that distributed vibration sensing is realized over such a long distance without inserting repeaters. The novel hybrid amplification scheme in this work can also be incorporated in other fiber-optic sensing systems for extension of sensing distance.

Graphene Bragg gratings on microfiber

Graphene Bragg gratings (GBGs) on microfiber are proposed and investigated in this paper. Numerical analysis and simulated results show that the mode distribution, transmission loss, and central wavelength of the GBG are controllable by changing the diameter of the microfiber or the refractive index of graphene. Such type of GBGs with tunability may find important applications in optical fiber communication and sensing as all-fiber in-line devices.

Phase-sensitive optical time-domain reflectometry with Brillouin amplification

We propose a phase-sensitive optical time-domain reflectometry (Φ-OTDR) scheme with counterpumping fiber Brillouin amplification (FBA). High-sensitivity perturbation detection over 100 km is experimentally demonstrated as an example. FBA significantly enhances the probe pulse signal, especially at the second half of the sensing fiber, with only 6.4 dBm pump power. It is confirmed that its amplification efficiency is much higher than 28.0 dBm counterpumping fiber Raman amplification. The FBA Φ-OTDR scheme demonstrated in this work can also be incorporated into other distributed fiber-optic sensing systems for extension of sensing distance or enhancement of sensing signal level.

Effectiveness of olfactory ensheathing cell transplantation for treatment of spinal cord injury

The aim of this study was to determine the effectiveness and safety of transplantation of olfactory ensheathing cells for functional repair of the spinal cord. An olfactory bulb was obtained from a 4- to 5-month-old aborted fetus, and it was digested into single olfactory ensheathing cells and then cultured and purified for 1 to 2 weeks. Under general anesthesia, these single-cell suspensions of olfactory ensheathing cells were injected into the corresponding spinal injury site with 0.45-mm-diameter injections. The American Spinal Injury Association (ASIA) Impairment Scale was used to evaluate spinal function. A total of 15 patients (12 men, 3 women; age range, 18-56 years; mean age, 40) were admitted for obsolete spinal injuries. Spinal functions of the 15 patients were observed and followed postoperatively for a period ranging from 2 weeks to 1 month. All the 15 patients exhibited improvements in spinal function, and the improvement tendencies continued. Twelve patients had obvious spinal function improvement, and three had slight improvement according to the ASIA scale, with an obvious difference between preoperation and postoperation measures (P < 0.05). No fevers, infections, functional deteriorations, or deaths were seen. Thus, transplantation of olfactory ensheathing cells promoted spinal and neurofunctional recovery in patients with malignant spinal injuries, and this therapeutic method was safe.

Random fiber laser formed by mixing dispersion compensated fiber and single mode fiber

Taking advantage of relatively strong Rayleigh scattering and Raman gain of dispersion compensated fiber (DCF), three configurations to form efficient random fiber lasers (RFL) are proposed in this paper. Compared with the reported RFL formed by single-mode fiber (SMF) solely, lasing threshold and length of the proposed RFL are effectively reduced through combination of DCF and SMF. In addition, FBGs with central wavelengths at the 1st and 2nd -order Raman Stokes wavelengths are also added to the hybrid SMF/DCF cavity to further reduce the lasing threshold, leading to realization of a new kind of 2nd-order RFL.

Hybrid lasing in an ultra-long ring fiber laser

In this paper, we reported the realization of an ultra-long ring fiber laser (RFL) with hybrid emission related to both random lasing and cavity resonance. Compared with a linear random fiber laser (LRFL), the Rayleigh scattering (RS) inducting distributed feedback effect and the cavity inducting resonance effect exist simultaneously in the laser, which reduces the lasing threshold considerably and provides a hybrid way to form random lasing (RL). The laser output can be purely modeless RL when pump power is high enough. It is also discovered that the laser is insensitive to temperature variation and mechanical disturbance, this is unique and quite different from conventional RFLs which are environmentally unstable due to existence of the cavity modes.

Long-distance fiber-optic point-sensing systems based on random fiber lasers

We find that the random fiber laser (RFL) without point-reflectors is a temperature-insensitive distributed lasing system for the first time. Inspired by such thermal stability, we propose the novel concept of utilizing the RFL to achieve long-distance fiber-optic remote sensing, in which the RFL offers high-fidelity and long-distance transmission for the sensing signal. Two 100 km fiber Bragg grating (FBG) point-sensing schemes based on RFLs are experimentally demonstrated using the first-order and the second-order random lasing, respectively, to verify the concept. Each sensing scheme can achieve >20 dB optical signal-to-noise ratio (OSNR) over 100 km distance. It is found that the second-order random lasing scheme has much better OSNR than that of the first-order random lasing scheme due to enhanced lasing efficiency, by incorporating a 1455 nm FBG into the lasing cavity.

All-fiber bandwidth-tunable band-rejection filter based on a composite grating induced by CO2 laser pulses

We propose an all-fiber band-rejection filter with a tunable bandwidth, which is realized by putting a normal long-period fiber grating in series with a rotary long-period fiber grating written in a twisted single-mode fiber by CO(2) laser pulses. Bandwidth tuning is achieved by applying torsion to the composite grating. Our experimental filter shows a bandwidth tuning of approximately 16.3 nm at a rejection level of approximately 15 dB and a polarization-dependent loss lower than approximately 0.9 dB.

ERK phosphorylation mediates sildenafil-induced myocardial protection against ischemia-reperfusion injury in mice

Sildenafil, a selective inhibitor of phosphodiesterase type 5, induces powerful protection against myocardial ischemia-reperfusion injury through activation of cGMP-dependent protein kinase (PKG). We further hypothesized that PKG-dependent activation of survival kinase ERK may play a causative role in sildenafil-induced cardioprotection via induction of endothelial nitric oxide synthase (eNOS)/inducible nitric oxide synthase (iNOS) and Bcl-2. Our results show that acute intracoronary infusion of sildenafil in Langendorff isolated mouse hearts before global ischemia-reperfusion significantly reduced myocardial infarct size (from 29.4 +/- 2.4% to 15.9 +/- 3.0%; P < 0.05). Cotreatment with ERK inhibitor PD98059 abrogated sildenafil-induced protection (31.8 +/- 4.4%). To further evaluate the role of ERK in delayed cardioprotection, mice were treated with sildenafil (ip) 24 h before global ischemia-reperfusion. PD98059 was administered (ip) 30 min before sildenafil treatment. Infarct size was reduced from 27.6 +/- 3.3% in controls to 7.1 +/- 1.5% in sildenafil-treated mice (P < 0.05). The delayed protective effect of sildenafil was also abolished by PD98059 (22.5 +/- 2.3%). Western blots revealed that sildenafil significantly increased phosphorylation of ERK1/2 and GSK-3beta and induced iNOS, eNOS, Bcl-2, and PKG activity in the heart 24 h after treatment. PD98059 inhibited the enhanced expression of iNOS, eNOS, and Bcl-2 and the phosphorylation of GSK-3beta. PD98059 had no effect on the sildenafil-induced activation of PKG. We conclude that these studies provide first direct evidence that PKG-dependent ERK phosphorylation is indispensable for the induction of eNOS/iNOS and Bcl-2 and the resulting cardioprotection by sildenafil.

Laser-micromachined Fabry-Perot optical fiber tip sensor for high-resolution temperature-independent measurement of refractive index

We propose and demonstrate a Fabry-Perot (F-P) optical fiber tip sensor for high-resolution refractive-index measurement fabricated by using 157-nm laser micromachining, for the first time to our knowledge. The sensor head consists of a short air F-P cavity near the tip of a single-mode fiber and the fiber tip. The external refractive index is determined according to the maximum fringe contrast of the interference fringes in the reflective spectrum of the sensor. Such a sensor can provide temperature-independent measurement of practically any refractive index larger than that of air and offers a refractive-index resolution of ~4 x 10(-5) in its linear operating range. The experimental data agree well with the theoretical results.

Miniature in-line photonic crystal fiber etalon fabricated by 157 nm laser micromachining

A miniature in-line fiber-optic Fabry-Perot etalon is fabricated on a photonic crystal fiber (PCF) by using 157 nm laser micromachining for the first time to our knowledge. Experimental results show that such a PCF-based etalon has an excellent fringe visibility of up to approximately 26 dB due to the mirror-finish quality of the two cavity surfaces inside the PCF. This etalon can be used as an ideal sensor for precise strain measurement under high temperature of up to 800 degrees C. It can also offer some other outstanding advantages, such as fast and easy fabrication, high reproducibility, capacity of mass production, low cost, low temperature-strain cross-sensitivity, and high signal-to-noise ratio.

In-line fiber-optic etalon formed by hollow-core photonic crystal fiber

A novel fiber-optic in-line etalon formed by splicing a section of hollow-core photonic crystal fiber (HCPCF) in between two single-mode fibers is proposed and demonstrated, for the first time to our knowledge. Such a HCPCF-based etalon acts as an excellent optical waveguide to form a Fabry-Perot interferometer and hence allows the cavity length to be as long as several centimeters with good visibility as the transmission loss of the HCPCF is much smaller than that of a hollow core fiber; this offers great potential to generate a practical dense fiber-optic sensor network with spatial frequency division-multiplexing. This novel etalon is demonstrated for strain measurement, and the experimental results show that a good visibility of 0.3 and a strain accuracy of better than +/- 5 microepsilon are achieved.

All-fiber dynamic gain equalizer based on a twisted long-period grating written by high-frequency CO2 laser pulses

A novel dynamic gain equalizer for flattening Er-doped fiber amplifiers based on a twisted long-period fiber grating (LPFG) induced by high-frequency CO(2) laser pulses is reported for the first time to our knowledge. Experimental results show that its transverse-load sensitivity is up to 0.34 dB/(g.mm(-1)), while the twist ratio of the twisted LPFG is approximately 20 rad/m, which is 7 times higher than that of a torsion-free LPFG. In addition, it is found that the strong orientation dependence of the transverse-load sensitivity of the torsion-free LPFG reported previously has been weakened considerably. Therefore such a dynamic gain equalizer based on the unique transverse-load characteristics of the twisted LPFG provides a much larger adjustable range and makes packaging of the gain equalizer much easier. A demonstration has been carried out to flatten an Er-doped fiber amplifier to +/-0.5 dB over a 32 nm bandwidth.

Fiber-optic Fabry-Perot sensors based on a combination of spatial-frequency division multiplexing and wavelength division multiplexing formed by chirped fiber Bragg grating pairs

Effective multiplexing for a very large number of fiber-optic fiber-Bragg-grating-based Fabry-Perot (FBGFP) sensors is proposed that is based on wavelength division multiplexing (WDM) and spatial-frequency division multiplexing (SFDM). For WDM, FBGFP sensors are arranged in different wavelength domains formed by a series of chirped fiber Bragg gratings with different central wavelengths while the sensors with different cavity lengths within the same wavelength domain are multiplexed by use of SFDM because they have different spatial frequencies as a result of their different cavity lengths. In principle, a thousand FBGFP sensors could be multiplexed with such an approach. The experimental results show that a strain accuracy of better than +/-10 microepsilon has been achieved with little cross talk.

Demodulation algorithm for spatial-frequency-division-multiplexed fiber-optic Fizeau strain sensor networks

A demodulation algorithm for spatial-frequency-division-multiplexed fiber-optic Fizeau strain sensor networks with a large number of sensors is proposed to effectively reduce the cross talk between any two adjacent sensors and hence substantially enhance the multiplexing capability of the network, which is based on the Pisarenko algorithm. The cross talk between two fiber-optic Fizeau sensors is investigated experimentally. The experimental results show that a strain accuracy of better than +/-10 micro permittivity can be achieved even when the cavity length difference is approximately 100 microm. It was demonstrated that the multiplexing capability of the spatial-frequency-division-multiplexed fiber-optic Fizeau sensor network can be approximately 5 times greater than that of the conventional fast-Fourier-transform algorithm, and this can lead to achievement of a sensing network with a multiplexing capability of as many as 1000 Fizeau sensors.

Optical in-fiber bragg grating sensor systems for medical applications

Two in-fiber Bragg grating (FBG) temperature sensor systems for medical applications are demonstrated: (1) an FBG flow-directed thermodilution catheter based on interferometric detection of wavelength shift that is used for cardiac monitoring; and (2) an FBG sensor system with a tunable Fabry-Perot filter for in vivo temperature profiling in nuclear magnetic resonance (NMR) machines. Preliminary results show that the FBG sensor is in good agreement with electrical sensors that are widely used in practice. A field test shows that the FBG sensor system is suitable for in situ temperature profiling in NMR machines for medical applications. © 1998 Society of Photo-Optical Instrumentation Engineers.

Dual-cavity interferometric wavelength-shift detection for in-fiber Bragg grating sensors

A dual-cavity interrogation method used to enhance the unambiguous measurement range of in-fiber Bragg grating sensors with high-resolution interferometric wavelength-shift detection is described. This novel technique is based on the use of two sets of fringes obtained with a stepped interferometric wavelength scanner with dual cavity lengths. We demonstrate the concept by interrogating an in-fiber grating temperature sensor with a stepped Michelson wavelength scanner.

Strain sensing of modern composite materials with a spatial/wavelength-division multiplexed fiber grating network

A spatial/wavelength-division multiplexing topology with combination of a tunable-wavelength filter and an interferometric wavelength scanner is used to interrogate a range of fiber Bragg grating (FBG) strain sensors embedded in modern composite materials. A nine-element FBG sensor system based on this topology is demonstrated for quasi-static strain sensing of a carbon fiber reinforced plastic plate for aerospace applications. Preliminary experimental results show that a strain resolution of ~1.8micro rms with an ~30-Hz bandwidth (~0.32micro/ radicalHz) for quasi-static strain measurement has been achieved.

Time-and-spatial-multiplexing tree topology for fiber-optic Bragg-grating sensors with interferometric wavelength-shift detection

A combined time-and-spatial-division-multiplexed tree topology with eight fiber-optic Bragg-grating sensors operating at the 830-nm wavelength was constructed and tested for both quasistatic and periodic strain and temperature measurements. The system uses a interferometric wavelength-shift discriminator and incorporates a reference channel for thermal drift compensation in the output. Dynamic sensor sensitivity, as determined by primary noise sources, is evaluated, and numerical results are presented and compared with experimental results.

Combined spatial- and time-division-multiplexing scheme for fiber grating sensors with drift-compensated phase-sensitive detection

A combined spatial- and time-division-multiplexing topology with drift-compensated high-resolution wavelength-shift detection is reported for fiber Bragg grating sensors. An eight-element grating sensor array is demonstrated based on this topology. A resolution of ~1.2 microepsilon over a range of ~1.5 mepsilon with a measurement bandwidth of 30 Hz (~0.22 microepsilon/ radicalHz) has been achieved for quasi-static strain measurement.

Delusions of parasitosis with fatal outcome

The case of a 40-year-old man with delusions of parasitosis as the presentation of a monodelusional psychosis is reported. In spite of treatment with pimozide and depot neuroleptics the patient committed suicide. Since the introduction of pimozide, this drug has come to be regarded as the specific treatment for this disorder; this case is presented to emphasize the fact that not all cases respond, and that the disorder can have a fatal outcome.

Prototype fiber-optic-based pressure probe with built-in temperature compensation with signal recovery by coherence reading

A prototype multimode fiber-based Fabry-Perot interferometric pressure probe utilizing a corrugated diaphragm with built-in temperature compensation, with signal recovery by coherence reading, has been constructed and demonstrated. A separate fiber-optic-based temperature sensor was incorporated into the pressure sensor to permit the pressure measurement to be corrected for the temperature dependence of the pressure probe. A measurement range to resolution of 3.6 × 10(4) - 1 and an overall measurement accuracy of ±0.15% have been achieved. This system represents a practical approach for industrial use.

Synthesized source for white-light sensing systems

We report a novel technique in which by combining the output from two multimode laser diodes a synthesized source with an extremely short coherence length is produced for use in white-light interferometric sensing systems. Experimentally and theoretically it is demonstrated that, by summing the autocorrelation function of two multimode laser diodes with a wavelength difference of 108 nm, a synthesized source with an equivalent coherence length of ~4 microm is generated, greatly reducing the signal-to-noise ratio required to identify the central fringe position.