Scintillator detector characterization for laser-driven proton beam imaging.

The spatial resolution and imaging characteristics of plastic scintillators are characterized using laser-driven proton beams. Laser-driven proton beams typically have broad energy spectra and are accompanied by relativistic electrons and high-energy photons, both potentially contributing to background noise. Different types and thicknesses of Eljen Technology scintillators are compared to determine their intrinsic point spread function. Point-projection imaging of a mesh is used to compare the imaging resolution of the scintillator to the usual imaging detector, radiochromic film, and is found to be reasonably comparable and sufficient for many experimental applications.

Enhanced spatial resolution of Eljen-204 plastic scintillators for use in rep-rated proton diagnostics.

A pixelated scintillator has been designed, fabricated, and tested using a laser-accelerated proton source for use in proton diagnostics at rep-rated laser facilities. The work presented here demonstrates the enhanced spatial resolution of thin, organic scintillators through a novel pixelation technique. Experimental measurements using laser-generated protons incident onto 130 µm-thick scintillators indicate a >20% reduction in the scintillator point spread function (PSF) for the detectors tested. The best performing pixelated detector reduced the ∼200 µm PSF of the stock material to ∼150 µm. The fabrication technique may be tailored to reduce the pixel size and achieve higher spatial resolutions.

Magnetic Signatures of Radiation-Driven Double Ablation Fronts.

In experiments performed with the OMEGA EP laser system, magnetic field generation in double ablation fronts was observed. Proton radiography measured the strength, spatial profile, and temporal dynamics of self-generated magnetic fields as the target material was varied between plastic, aluminum, copper, and gold. Two distinct regions of magnetic field are generated in mid-Z targets-one produced by gradients from electron thermal transport and the second from radiation-driven gradients. Extended magnetohydrodynamic simulations including radiation transport reproduced key aspects of the experiment, including field generation and double ablation front formation.

Size at birth in an inner-city population.

Recent comparisons of growth curves and incidence of low birth weight are available for Caucasians and African-Americans or Hispanics. To compare size at birth in Hispanics with African-Americans in an inner-city population, we analyzed data on mother-infant pairs admitted to Jacobi Medical Center from January 1, 1995 until May 31, 1997 and those with a gestational age less than 34 weeks admitted from June 1, 1997 until December 31, 1997. The population mostly included mothers covered by Medicaid. The study sample included 2852 infants (1641 Hispanics and 1211 African-Americans). Among singletons, the incidence of teenage pregnancy was higher and those of premature delivery and low birth weight were lower in Hispanics than in African-Americans. Among full-term singletons, boys were heavier than girls (difference 116 g, confidence interval (CI) 57,174, p < 0.001 after adjusting for gestational age, gender, and teenage pregnancy), and Hispanics were heavier than African-Americans (adjusted difference 70 g, Confidence Interval (CI) 11,128, p = 0.019). Additional studies are needed to assess the effect of race on neonatal size after adjusting for differences in prepregnancy weight, weight gain, parity, social class, or other factors.

Relationship between perinatal counseling and incidence of breastfeeding in an inner-city population.

OBJECTIVE: We hypothesized that the cost of a lactation program can be reduced without significantly affecting the incidence of breastfeeding. STUDY DESIGN: We conducted a retrospective analysis of breastfeeding among all 7942 mothers whose neonates were admitted to the well baby nursery at Jacobi Medical Center (JMC) over a 44-month period. We used multiway frequency analysis to compare the incidence of breastfeeding in three successive models of counseling: (1) full-time lactation coordinator, (2) obstetric personnel trained in breastfeeding counseling and full-time lactation coordinator, and (3) obstetric personnel and half-time lactation coordinator. Mothers were further classified into three groups according to location of prenatal care and attendance at breastfeeding education sessions. RESULTS: Breastfeeding increased with the initiation of education and the involvement of obstetric personnel and did not significantly decrease when the lactation coordinator became half-time. The transition to model 3 resulted in decreased costs without significantly affecting the incidence of breastfeeding. Breastfeeding was significantly associated with counseling by obstetric personnel, with prenatal care at JMC, and with breastfeeding education sessions. CONCLUSION: Involving obstetric personnel in breastfeeding counseling may enhance the effectiveness of a lactation program. In our population, the most cost-conscious model included counseling by trained obstetric personnel and a half-time lactation coordinator.

Percutaneous catheter placement for cyst drainage in the subarachnoid space.

A technique for percutaneous catheter drainage of cystic masses in the subarachnoid space was developed and shown to be safe and effective in an 18-year-old boy with life-threatening, recurrent neuroenteric cysts that compressed the brain stem, cerebellum, and spinal cord. Percutaneous drainage through a C1-C2 approach was performed on 11 separate occasions. Decompression was always accomplished and no infection or other complication occurred, even with continuous catheter drainage for 9 months. This technique provides opportunities for interventional neuroradiologic therapy in the subarachnoid space. It appears to be suited for percutaneous drainage of intraspinal and intracranial cysts when surgery is not indicated due to intractability or inaccessibility.