Biomedical subjects

Lisa Forrest

Publications and source records attributed to Lisa Forrest.

5 recordsLinked to original sources

PubMed2006

Clinical implementation of adaptive helical tomotherapy: a unique approach to image-guided intensity modulated radiotherapy.

Image-guided IMRT is a revolutionary concept whose clinical implementation is rapidly evolving. Methods of executing beam intensity modulation have included individually designed compensators, static multi-leaf collimators (MLC), dynamic MLC, and sequential (serial) tomotherapy. We have developed helical tomotherapy as an innovative solution to overcome some of the limitations of other IMRT systems. The unique physical design of helical tomotherapy allows the realization of the concepts of adaptive radiotherapy and conformal avoidance. In principle, these advances should improve normal tissue sparing and permit dose reconstruction and verification, thereby allowing significant biologically effective dose escalation. Recent radiobiological findings can be translated into altered fractionation schemes that aim to improve the local control and long-term survival. This strategy is being tested at the University of Wisconsin using helical tomotherapy with its highly precise delivery and verification system along with meticulous and practical forms of immobilization. Innovative techniques such optical guidance, respiratory gating, and ultrasound assessments are being designed and tailored for helical tomotherapy use. The intrinsic capability of helical tomotherapy for megavoltage CT (MVCT) imaging for IMRT image-guidance is being optimized. The unique features of helical tomotherapy might allow implementation of image-guided IMRT that was previously impossible or impractical. Here we review the technological, physical, and radiobiological rationale for the ongoing and upcoming clinical trials that will use image-guided IMRT in the form of helical tomotherapy; and we describe our plans for testing our hypotheses in a rigorous prospective fashion.

Humans↗

PubMed2003

Image guidance for precise conformal radiotherapy.

PURPOSE: To review the state of the art in image-guided precision conformal radiotherapy and to describe how helical tomotherapy compares with the image-guided practices being developed for conventional radiotherapy. MATERIALS AND METHODS: Image guidance is beginning to be the fundamental basis for radiotherapy planning, delivery, and verification. Radiotherapy planning requires more precision in the extension and localization of disease. When greater precision is not possible, conformal avoidance methodology may be indicated whereby the margin of disease extension is generous, except where sensitive normal tissues exist. Radiotherapy delivery requires better precision in the definition of treatment volume, on a daily basis if necessary. Helical tomotherapy has been designed to use CT imaging technology to plan, deliver, and verify that the delivery has been carried out as planned. The image-guided processes of helical tomotherapy that enable this goal are described. RESULTS: Examples of the results of helical tomotherapy processes for image-guided intensity-modulated radiotherapy are presented. These processes include megavoltage CT acquisition, automated segmentation of CT images, dose reconstruction using the CT image set, deformable registration of CT images, and reoptimization. CONCLUSIONS: Image-guided precision conformal radiotherapy can be used as a tool to treat the tumor yet spare critical structures. Helical tomotherapy has been designed from the ground up as an integrated image-guided intensity-modulated radiotherapy system and allows new verification processes based on megavoltage CT images to be implemented.

Animals↗

PubMed2002

Projection neurons in lamina I of rat spinal cord with the neurokinin 1 receptor are selectively innervated by substance p-containing afferents and respond to noxious stimulation.

Lamina I of the spinal cord is densely innervated by nociceptive primary afferents, many of which contain substance P. It contains numerous projection neurons: the majority of these respond to noxious stimuli, however some are activated by cooling. In the rat, approximately 80% of the projection neurons express the neurokinin 1 (NK1) receptor, on which substance P acts, and most cells with this receptor are activated by noxious stimuli. Lamina I neurons can be classified morphologically into pyramidal, multipolar, and fusiform types. It has been reported in the cat that pyramidal neurons are activated only by cooling and that in monkey relatively few pyramidal cells are NK1 receptor-immunoreactive. We have used immunocytochemistry to examine the innervation of lamina I projection neurons in the rat by substance P-containing primary afferents and their responses to a noxious stimulus (subcutaneous formalin injection). NK1 receptor-immunoreactive projection cells received a significantly higher density of contacts from substance P-containing afferents than neurons that lacked the receptor. Most contacts on NK1 receptor-immunoreactive cells were associated with synapses. Formalin injection induced c-Fos in approximately 80% of projection neurons with the NK1 receptor and in 25-45% of those without it. More than 80% of pyramidal neurons expressed the receptor, and for both substance P innervation and c-Fos expression there were no significant differences among different morphological types of NK1 receptor-immunoreactive neuron. We conclude that presence or absence of the NK1 receptor is a better indicator of function than morphology for lamina I projection neurons in the rat.

Animals↗

PubMed2002

Eyelid lymphatics I: histochemical comparisons between the monkey and human.

PURPOSE: To study the lymphatic drainage of the cynomolgus monkey and human eyelid and periocular tissue by means of histochemistry. METHODS: Eyelid and periocular tissue from three cynomolgus monkeys undergoing sacrifice for glaucoma and retina research purposes and discarded tissue from a wedge resection of one human eyelid were used for histochemical analysis. Lymphatic capillaries were distinguished histochemically in monkey and human eyelids by light microscopy with a 5'-nucleotidase (5'-Nase) staining method. Identification of lymphatic vessels was based on strict morphologic criteria combined with specific 5'-Nase staining. RESULTS: Histochemical analysis with 5'-nucleotidase revealed a subcutaneous and pretarsal lymphatic plexus in both the human and monkey. CONCLUSIONS: Histochemical results demonstrate similar lymphatic plexi in the monkey and human. Future studies will help to clarify the lymphatic drainage pathways of monkey and human eyelids.

5'-Nucleotidase↗

PubMed2002

Eyelid lymphatics II: a search for drainage patterns in the monkey and correlations with human lymphatics.

PURPOSE: To study the lymphatic drainage of the cynomolgus monkey through the use of lymphoscintigraphy. METHODS: Lymphoscintigraphy with 500 microCi of 99mTechnetium sulfur colloid injected at specific sites around the eyelids was performed with five cynomolgus monkeys in lateral and ventral positions. RESULTS: Lymphoscintigraphy of the monkey eyelid and periocular tissue revealed lymphatic drainage to the parotid lymph nodes from the entire upper eyelid, medial canthus, and lateral lower eyelid and drainage to the submandibular lymph nodes from the medial and central lower eyelid. In addition to draining to the parotid lymph nodes, the central upper eyelid was also seen to drain to the submandibular lymph nodes. CONCLUSIONS: Lymphoscintigraphy of the cynomolgus monkey eyelids reveals discrete lymphatic drainage pathways for the upper and lower eyelids and a dual pathway for the central upper eyelid. Future studies will help to clarify the lymphatic drainage pathways of human eyelids.

Animals↗