In order to assess the place of computed tomography (CT) in radiotherapy planning, the tumor volumes are localized both by conventional techniques and with CT scanning under conditions simulating the ...radiotherapy. A comparison between the two methods has been made in a group of 55 patients with tumors in the pelvis. CT scanning was found to be of such value in 64% of the treatment series, in improving both the accuracy of localization of the target volume (48% of the patients) and the calculation of the dose distribution (31% of the patients) that its use is recommended during the radiotherapy planning of pelvic tumors.
Computed tomography can provide precise information for radiation therapy treatment planning. However, inaccuracies in radiation field design may occur when the radiation oncologist attempts to ...transfer information about tumor location from the transverse plane of the CT scan to the longitudinal plane of the simulation film. This report describes a new computer program, LOCATE, which addresses this problem. The program uses operator generated information from the cross sectional CT images to draw an outline of tumor on AP and lateral longitudinal scanned projection radiographs. The resultant images are useful because they are in the same plane as radiographs obtained on a therapy simulator. The impact of LOCATE on radiation treatment planning for 26 patients is discussed along with several cases in which LOCATE was particularly helpful.
In radiation therapy of patients with breast carcinoma, the ipsilateral internal mammary lymph nodes are either irradiated by a separate anterior field or included by isocentric opposing tangential ...fields, which also treat the breast and chest wall. To determine the acceptability of a particular treatment setup, the positions of the nodes must be determined with respect to the treatment fields. For the anterior field technique the problem is two-dimensional and is solved by simply superimposing the treatment field onto an anterior lymphoscintigram. For treatment by opposing tangential fields the problem is three-dimensional and more complex. The solution described in this note is to project the three-dimensional lymph node positions, obtained by a stereo-lymphoscintigraphic procedure, onto the tangential field radiographs. A mathematical expression is given to perform the required projection of the node positions onto the radiographs.
The administration of adequate doses of radiation to tumors involving the orbit and surrounding facial structures and sinuses is often complicated by the need to protect the sensitive ocular ...components, the lens and cornea. A technique has been devised that uses four photon beam fields and an optional electron field to treat the contents of both orbits and adjacent sinuses with effective, reproducible protection of cornea and lens. Essential features include: alignment of the corneal surfaces with the central plane of rotation of the treatment machine, use of a narrow eye block across the entire beam to shield a strip equal to the width of the cornea, positioned symmetrically across the central plane of rotation, fine alignment of the eye block with both corneal surfaces by altering pedestal angle, treatment with paired, wedged, anterior oblique fields to encompass desired orbital and sinus volumes with additional blocking placed as needed, and complementary, lateral strip fields using collimators set to eye block thickness to equalize dose in the posterior orbit shielded by the strip eye block. A similar anterior electron beam strip field may be added to boost the medial orbit and ethmoid regions covered by the eye block. Bite block head immobilization and easy, direct daily visualization of block position assures eye protection for each treatment and provides substantial reduction in dose to the cornea, lens and iris. Additional blocking may be incorporated to provide partial lacrimal and parotid sparing.
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GEOZS, IJS, NUK, OILJ, UL, UM, UPUK
Computer generated images for medical applications Sunguroff, Alexander; Greenberg, Donald
Proceedings of the 5th annual conference on Computer graphics and interactive techniques,
08/1978
Conference Proceeding
Two computer graphics systems for the presentation of biomedical information for diagnosis and treatment planning are described. Both systems presented utilize computer tomographic (CT) data as ...input. One of the systems produces three-dimensional surface representations of organs and anatomical features found within the body. The other system is a radiation treatment planning aid which uses tomographic data in its computations.
