Biomedical subjects

Daniel Fried

Publications and source records attributed to Daniel Fried.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Light scattering properties of natural and artificially demineralized dental enamel at 1310 nm.

A fundamental understanding of how near-IR light propagates through sound and carious dental hard tissues is essential for the development of clinically useful optical diagnostic systems, since image contrast is based on changes in the optical properties of these tissues on demineralization. During the caries (decay) process, micropores are formed in the lesion due to partial dissolution of the individual mineral crystals. Such small pores behave as scattering centers, strongly scattering visible and near-IR light. The optical properties of enamel can be quantitatively described by the absorption and scattering coefficients, and the scattering phase function. Our aim is to measure the optical scattering behavior of natural and artificial enamel caries. Near-IR attenuation measurements and angular-resolved goniometer measurements coupled with Monte Carlo simulations are used to determine changes in the scattering coefficient and the scattering anisotropy on demineralization at 1310 nm. An ultra-high resolution digital microradiography system is used to quantify the lesion severity by measurement of the relative mineral loss for comparison with optical scattering measurements. The scattering coefficient increases exponentially with increasing mineral loss. Natural and artificial demineralization increases the scattering coefficient more than two orders of magnitude at 1310 nm, and the scattering is highly forward directed.

Dental Caries↗

PubMedDate not supplied

Rapid and conservative ablation and modification of enamel, dentin, and alveolar bone using a high repetition rate transverse excited atmospheric pressure CO2 laser operating at lambda=9.3 micro.

Transverse excited atmospheric pressure (TEA) CO(2) lasers tuned to the strong mineral absorption of hydroxyapatite near lambda=9 microm are well suited for the efficient ablation of dental hard tissues if the laser pulse is stretched to greater than 5 to 10 micros to avoid plasma shielding phenomena. Such CO(2) lasers are capable of operating at high repetition rates for the rapid removal of dental hard tissues. The purpose of this study was to test the hypothesis that stretched lambda=9.3-microA CO(2) laser pulses can produce lateral incisions in enamel, dentin, and alveolar bone for dental restorations and implants at repetition rates as high as 400 Hz without peripheral thermal damage. The single pulse ablation rates through enamel, dentin, and bone were determined for incident fluence ranging from (1 to 160 J/m(2)) for laser pulses from 5 to 18 mus in duration. Lateral incisions were produced in hard tissue samples using a computer-controlled scanning stage and water spray, and the crater morphology and chemical composition were measured using optical microscopy and high-resolution synchrotron radiation infrared spectromicroscopy. The residual energy remaining in tooth samples was measured to be 30 to 40% for enamel and 20 to 30% for dentin without water cooling, under optimum irradiation intensities, significantly lower than for longer CO(2) laser pulses. The transmission through 2-m length 300-, 500-, 750-, and 1000-microm silica hollow waveguides was measured and 80% transmission was achieved with 40 mJ per pulse. These results suggest that high repetition rate TEA CO(2) laser systems operating at lambda=9.3 microm with pulse durations of 10 to 20 micros are well suited for dental applications.

Animals↗

PubMedDate not supplied

Combined modality therapy for stage III non-small cell lung cancer.

Lung cancer remains the leading cause of cancer death in the U.S. among both men and women. Approximately 45% of patients present with stage III disease. A proportion of these patients is amenable to surgical resection; however, the majority are "unresectable." For patients with unresectable stage IIIA/B disease, thoracic radiation therapy (TRT) was considered the standard of care until the late 1980s despite a very poor 5-year survival rate. Several clinical trials demonstrated that the combination of chemotherapy and TRT was superior to TRT alone. Based on these data, combined modality therapy became the standard of care for patients with good performance status. Recent trials have shown that concurrent chemoradiotherapy offers a significant survival advantage over sequential chemoradiotherapy. Despite a substantial number of clinical trials, important questions on the optimal treatment paradigm remain. The most effective chemotherapy combination, the use of induction or consolidation chemotherapy in addition to the concurrent portion of therapy, and the optimal dose of chemotherapy with concurrent TRT have yet to be determined. The optimal total dose, fractionation, acceleration, treatment volume, and tumor targeting remain questions related to the TRT portion of therapy. Although significant progress has been made, the majority of patients experience locoregional or distant progression of their disease and die within 5 years of diagnosis. Thus, continued development and participation in clinical trials is crucial to further improvements in the treatment of patients with stage III disease.

Antineoplastic Combined Chemotherapy Protocols↗