Biomedical subjects

T McNutt

Publications and source records attributed to T McNutt.

6 recordsLinked to original sources

PubMed1999

Tomotherapy.

Tomotherapy is delivery of intensity-modulated, rotational radiation therapy using a fan-beam delivery. The NOMOS (Sewickley, PA) Peacock system is an example of sequential (or serial) tomotherapy that uses a fast-moving, actuator-driven multileaf collimator attached to a conventional C-arm gantry to modulate the beam intensity. In helical tomotherapy, the patient is continuously translated through a ring gantry as the fan beam rotates. The beam delivery geometry is similar to that of helical computed tomography (CT) and requires the use of slip rings to transmit power and data. A ring gantry provides a stable and accurate platform to perform tomographic verification using an unmodulated megavoltage beam. Moreover, megavoltage tomograms have adequate tissue contrast and resolution to provide setup verification. Assuming only translational and rotational offset errors, it is also possible to determine the offsets directly from tomographic projections, avoiding the time-consuming image reconstruction operation. The offsets can be used to modify the leaf delivery pattern to match the beam to the patient's anatomy on each day of a course of treatment. If tomographic representations of the patient are generated, this information can also be used to perform dose reconstruction. In this way, the actual dose distribution delivered can be superimposed onto the tomographic representation of the patient obtained at the time of treatment. The results can be compared with the planned isodose on the planning CT. This comparison may be used as an accurate basis for adaptive radiotherapy whereby the optimized delivery is modified before subsequent fractions. The verification afforded tomotherapy allows more precise conformal therapy. It also enables conformal avoidance radiotherapy, the complement to conformal therapy, for cases in which the tumor volume is ill-defined, but the locations of sensitive structures are adequately determined. A clinical tomotherapy unit is under construction at the University of Wisconsin.

Dose Fractionation, Radiation↗

PubMed1999

Assessment of the strength of individual 192Ir seeds in ribbons.

Assessing the strength of individual seed-type sources in ribbon assembles remains a challenge in brachytherapy quality assurance. Geometries to measure a single source in the ribbon usually fail because of low signals if using very thick shielding to block the radiation from the other sources, or contributions from all the other sources if they are not shielded well. A normal well-type chamber with partial lead shielding forming a small slot provides a differential response along the chamber axis that, through a deconvolution/simultaneous-equations technique, sorts the contributions from each source, allowing the derivation of each source's strength.

Brachytherapy↗

PubMed1996

A consistency monitor for radiation therapy treatments.

A thin, large area transparent transmission chamber mounted below the accessory tray is described and its suitability for daily treatment delivery consistency is investigated. The sensitivity of the detector to changes in monitor unit setting, field size, wedge size, missing blocks, and wedges is presented. Some of the other potential applications are also discussed.

Humans↗

PubMed1992

Adsorption of oviductal fluid proteins by the bovine sperm membrane during in vitro capacitation.

125I-labeled oviductal fluid (ODF) proteins and antiserum to ODF were used to determine whether ODF proteins associate with the sperm membrane during in vitro capacitation. Luteal and nonluteal pools of ODF were obtained from oviduct catheters during the estrous cycle. Washed sperm (50 x 10(6) sperm/ml) were incubated up to 4 h in a protein-free modified Tyrode's medium (MTM), or MTM supplemented with 40% ODF, or 0.5 ng 125I-labeled ODF proteins. Solubilized sperm membrane proteins and incubation media containing ODF proteins were separated by gel electrophoresis. Membranes isolated from bovine sperm, previously incubated with ODF, adsorbed five 125I-proteins: A doublet at 85-95 kDa, and others at 24, 34, 53, and 66 kDa. The amount of 66 kDA 125I-protein associated with the sperm decreased during the incubation, whereas the amount of 85 to 95-kDa protein did not. Western blot analyses also detected the presence of ODF proteins (53, 66, 85-95, and 116 kDa) in solubilized membranes from sperm incubated in ODF. The 85 to 95-kDa protein in ODF decreased in apparent molecular weight by 5 kDa when associated with the sperm membrane. At 53 kDa, ODF proteins which associated with sperm were transformed from two to three separate proteins. These studies indicate that the surface of sperm is modified by adsorption of ODF proteins to the membrane during in vitro capacitation.

Adsorption↗

PubMed1989

Evaluation of butylated hydroxytoluene as a cryopreservative added to whole or skim milk diluent for bull semen.

Effect of five concentrations of butylated hydroxytoluene on the percent motility and percent intact acrosomes was evaluated for bull sperm frozen and thawed in whole and skim milk diluents. Twelve ejaculates were frozen in .5-ml straws in moving nitrogen vapor after each ejaculate was split among the five butylated hydroxytoluene treatments within the two diluents. Prefreeze and postthaw percent motility and postthaw percent intact acrosomes were evaluated at 0 and 4 h. Before freezing, sperm motilities were similar in whole or skim milk diluents with and without butylated hydroxytoluene. Upon thawing, sperm motility was 10 percentage points higher in whole milk diluent containing .5 and .75 mM butylated hydroxytoluene than in samples without it. After 4 h, percentage motile sperm was similar among all whole milk treatments. Sperm motility was similar among all skim milk treatments at both 0 and 4 h. Percent intact acrosomes were similar among all treatments for each diluent. Oxidation in whole milk diluent stored at 4 degrees C for 1 wk was reduced in the presence of 1.0, 2.0, and 4.0 mM butylated hydroxytoluene.

Acrosome↗

PubMed1989

Oral trauma in adolescent athletes: a study of mouth protectors.

The purpose of this study was to determine the extent of mouth protector use, as well as the amount and type of oral trauma associated with and without mouth guard wear in adolescent athletes. Coaches' perceptions and regulations involving the use of mouth protectors also were examined. Interviews were collected from 2470 junior and senior high school football players with all oral trauma being documented, regardless of the sport during which the injury occurred. Nine per cent of all players suffered from some form of oral injury while another 3% reported a loss of consciousness. Seventy-five per cent of the injuries occurred while not wearing mouth guards, and of this total 40% occurred during baseball and basketball. Fifty-six per cent of all concussions were suffered while not wearing mouth guards. Despite the ability of mouth protectors to significantly help reduce oral injuries, trauma related to sports is more prevalent than previously reported. This study supports the recommendation of mandatory mouth guards in baseball and basketball.

Adolescent↗