Radiant energy – Source with recording detector – Using a stimulable phosphor
Patent
1996-09-24
1997-08-26
Fields, Carolyn E.
Radiant energy
Source with recording detector
Using a stimulable phosphor
250337, 250580, G01T 1105, G01T 1115
Patent
active
056613105
DESCRIPTION:
BRIEF SUMMARY
1. Technical Field
This invention relates to dose mapping of spacially variable radiation patterns, particularly of radiation patterns as are used in medical radiation treatment.
2. Background Art
Radiation therapy is used in the treatment of various medical conditions. In many cases such radiation treatments seek to apply a relatively greater dose of radiation at some specific location, for example, to a cancerous tumor located in a position within the human body. Therefore, it is usually necessary, prior to actual patient treatment, to design a radiation exposure plan or design which uses one or more radiation beams of varying shape, size, strength, intensity, convergence, orientation or duration. Such exposure plans can direct the various beam or beams at the specific region of tissue which is to be treated, while minimizing the radiation dose beamed to adjacent tissues. Avoiding radiation exposure of adjacent tissues becomes especially important where the tissues being treated are adjacent to tissues which are particularly sensitive to radiation injury, such as adjacent to optic nerves, brain tissues, and other tissues.
In an effort to minimize the radiation damage to surrounding tissues, the medical profession uses simulated human models; typically called phantoms. The phantoms are used to help devise and analyze proposed radiation dose plans prior to actual patient exposure. The phantoms are preferably three-dimensional models having dimensions similar to the person being treated. The materials used to make the phantoms are selected to simulate the radiation absorbance of the tissues of the body or body parts being modeled. This tissue-equivalency is important to good modeling and analysis. Despite using a great degree of care, the determination of radiation doses is a difficult science and requires interpretive and predictive judgment by the practicing radiologist.
Prior art radiation treatment dose mapping systems have utilized radiation sensitive photographic films such as X-ray films, which are positioned at appropriate locations within a phantom during administration of proposed radiation doses. Such films must be developed using relatively time consuming chemical procedures. This slows the treatment planning process and reduces the number of tests and the precision of treatment designs which might otherwise be obtained.
An alternative approach has been to utilize one or more discrete radiation intensity probes during test dose administration. This approach suffers from not providing two-dimensional or three-dimensional maps of radiation exposure over the areas or spaces of a phantom patient. A continuous distribution mapping is highly desirable in order to precisely identify spacial coordinates of radiation peaks and to more efficiently fine tune or adjust radiation sources to achieve desired dose concentrations at the desired spatial coordinates relative to the phantom and patient.
The invention described below provides a system for improved mapping of spacially variable radiation patterns such as used in medical radiation treatment. The apparatus and methods of the invention may find additional application in such fields as mapping of accelerator beam profiles and mapping of radiation patterns used to test electronic circuits and other devices for radiation hardness. The invention provides the advantages of substantially continuous field mapping, to provide dose images. Additionally, the dynamic range is improved in most instances as compared to prior technologies. The present invention may also help in eliminating other disadvantages of prior technologies. The apparatus and methods of the invention allow for high speed radiation dose mapping without the requirement of chemical processing while providing a dose image of good resolution and good dynamic range.
BRIEF DESCRIPTION OF THE DRAWINGS
One or more preferred forms of the invention are described herein with reference to the accompanying drawings. The drawings are briefly described below.
FIG. 1 is a front view of a dose map radiation
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Fields Carolyn E.
Glick Edward J.
Keithley Instruments Inc.
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