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Title: Intraocular radiation blocking

Abstract

Iodine-based liquid radiographic contrast agents were placed in normal and tumor-bearing (Greene strain) rabbit eyes to evaluate their ability to block iodine-125 radiation. This experiment required the procedures of tumor implantation, vitrectomy, air-fluid exchange, and 125I plaque and thermoluminescent dosimetry (TLD) chip implantation. The authors quantified the amount of radiation attenuation provided by intraocularly placed contrast agents with in vivo dosimetry. After intraocular insertion of a blocking agent or sham blocker (saline) insertion, episcleral 125I plaques were placed across the eye from episcleral TLD dosimeters. This showed that radiation attenuation occurred after blocker insertion compared with the saline controls. Then computed tomographic imaging techniques were used to describe the relatively rapid transit time of the aqueous-based iohexol compared with the slow transit time of the oil-like iophendylate. Lastly, seven nontumor-bearing eyes were primarily examined for blocking agent-related ocular toxicity. Although it was noted that iophendylate induced intraocular inflammation and retinal degeneration, all iohexol-treated eyes were similar to the control eyes at 7 and 31 days of follow-up. Although our study suggests that intraocular radiopaque materials can be used to shield normal ocular structures during 125I plaque irradiation, a mechanism to keep these materials from exiting the eye must be devisedmore » before clinical application.« less

Authors:
; ; ; ; ; ;  [1]
  1. (North Shore Univ. Hospital, Manhasset, NY (USA))
Publication Date:
OSTI Identifier:
6141673
Resource Type:
Journal Article
Resource Relation:
Journal Name: Investigative Ophthalmology and Visual Science; (USA); Journal Volume: 31:9
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; CONTRAST MEDIA; RADIOSENSITIVITY EFFECTS; EYES; EXPERIMENTAL NEOPLASMS; COMPUTERIZED TOMOGRAPHY; IODINE 125; RABBITS; THERMOLUMINESCENT DOSIMETRY; ANIMALS; BETA DECAY RADIOISOTOPES; BODY; BODY AREAS; DAYS LIVING RADIOISOTOPES; DIAGNOSTIC TECHNIQUES; DOSIMETRY; ELECTRON CAPTURE RADIOISOTOPES; FACE; HEAD; INTERMEDIATE MASS NUCLEI; IODINE ISOTOPES; ISOTOPES; MAMMALS; NUCLEI; ODD-EVEN NUCLEI; ORGANS; RADIOISOTOPES; SENSE ORGANS; TOMOGRAPHY; VERTEBRATES; 550603* - Medicine- External Radiation in Therapy- (1980-)

Citation Formats

Finger, P.T., Ho, T.K., Fastenberg, D.M., Hyman, R.A., Stroh, E.M., Packer, S., and Perry, H.D. Intraocular radiation blocking. United States: N. p., 1990. Web.
Finger, P.T., Ho, T.K., Fastenberg, D.M., Hyman, R.A., Stroh, E.M., Packer, S., & Perry, H.D. Intraocular radiation blocking. United States.
Finger, P.T., Ho, T.K., Fastenberg, D.M., Hyman, R.A., Stroh, E.M., Packer, S., and Perry, H.D. 1990. "Intraocular radiation blocking". United States. doi:.
@article{osti_6141673,
title = {Intraocular radiation blocking},
author = {Finger, P.T. and Ho, T.K. and Fastenberg, D.M. and Hyman, R.A. and Stroh, E.M. and Packer, S. and Perry, H.D.},
abstractNote = {Iodine-based liquid radiographic contrast agents were placed in normal and tumor-bearing (Greene strain) rabbit eyes to evaluate their ability to block iodine-125 radiation. This experiment required the procedures of tumor implantation, vitrectomy, air-fluid exchange, and 125I plaque and thermoluminescent dosimetry (TLD) chip implantation. The authors quantified the amount of radiation attenuation provided by intraocularly placed contrast agents with in vivo dosimetry. After intraocular insertion of a blocking agent or sham blocker (saline) insertion, episcleral 125I plaques were placed across the eye from episcleral TLD dosimeters. This showed that radiation attenuation occurred after blocker insertion compared with the saline controls. Then computed tomographic imaging techniques were used to describe the relatively rapid transit time of the aqueous-based iohexol compared with the slow transit time of the oil-like iophendylate. Lastly, seven nontumor-bearing eyes were primarily examined for blocking agent-related ocular toxicity. Although it was noted that iophendylate induced intraocular inflammation and retinal degeneration, all iohexol-treated eyes were similar to the control eyes at 7 and 31 days of follow-up. Although our study suggests that intraocular radiopaque materials can be used to shield normal ocular structures during 125I plaque irradiation, a mechanism to keep these materials from exiting the eye must be devised before clinical application.},
doi = {},
journal = {Investigative Ophthalmology and Visual Science; (USA)},
number = ,
volume = 31:9,
place = {United States},
year = 1990,
month = 9
}
  • It had been previously observed that if the crystalline minimum which were determined by growth on a Petri dish in 2% agar. A definite amount of intact bacteriophage T-4 was added to the control and irradiated solutions, and the number of bacteriophage particles was determined by the agar layer method of Gratsii. The results show that bacteria lose their ability to fission after irradiation with large doses, but retain their ability to reproduce bacteriophage. The ability of irradiated bacteria to reproduce bacteriophage after having lost their ability to fission is proof of the radio-resistance of ferment systems. (TTT).
  • Hyperthermia and radiation were used in combination to treat four patients with choroidal malignant melanoma. This technique uses ultrasonically induced hyperthermia synergistically with radiation to destroy tumor cells. The lower levels of radiation used should avoid the late vascular and inflammatory complications seen in conventional radiation therapy. Tumors were scanned by a computerized diagnostic ultrasound system before treatment and assigned an acoustic tissue type on the basis of a statistical comparison of their ultrasound backscatter spectrum with spectra of tumors of known pathologic status. During the follow-up period, the longest of which was 15 months, all tumors demonstrated regression patternsmore » consistent with choroidal tumors of the same acoustic tissue types treated with conventional radiation therapy.« less
  • Purpose: To study the optimization of proton beam arrangements for various intraocular tumor locations; and to correlate isodose distributions with various target and nontarget structures. Methods and materials: We considered posterior-central, nasal, and temporal tumor locations, with straight, intrarotated, or extrarotated eye positions. Doses of 46 cobalt grey equivalent (CGE) to gross tumor volume (GTV) and 40 CGE to clinical target volume (CTV) (2 CGE per fraction) were assumed. Using three-dimensional planning, we compared isodose distributions for lateral, anterolateral oblique, and anteromedial oblique beams and dose-volume histograms of CTVs, GTVs, lens, lacrimal gland, bony orbit, and soft tissues. Results: Allmore » beam arrangements fully covered GTVs and CTVs with optimal lens sparing. Only 15% of orbital bone received doses {>=}20 CGE with a lateral beam, with 20-26 CGE delivered to two of three growth centers. The anterolateral oblique approach with an intrarotated eye resulted in additional reduction of bony volume and exposure of only one growth center. No appreciable dose was delivered to the contralateral eye, brain tissue, or pituitary gland. Conclusions: Proton therapy achieved homogeneous target coverage with true lens sparing. Doses to orbit structures, including bony growth centers, were minimized with different beam arrangements and eye positions. Proton therapy could reduce the risks of second malignancy and cosmetic and functional sequelae.« less