We have located links that may give you full text access.
The width of margins in radiotherapy treatment plans.
Physics in Medicine and Biology 2000 November
Publication of ICRU Reports 50 and 62 has highlighted the need to devise protocols for the process of drawing the planning target volume (PTV) around the clinical target volume (CTV). The margin surrounding the CTV should be wide enough to account for all geometric errors so that no part of the CTV accumulates a dose less than, for instance, 95% of that prescribed. One approach to the problem has been to draw a margin around the CTV delineated at the treatment preparation stage which is sufficiently wide that the mean position of the CTV will be encompassed in a specific percentage of cases, for example 90%. This accounts for the systematic errors. A further margin is then drawn to account for random set-up and organ-motion uncertainties during treatment. The width of this second margin has previously been shown to be 1.64(sigma - sigmap). Here sigma, a vector quantity, is the standard deviation which results from convolving the penumbra spread function of standard deviation sigmap with the Gaussian distributions of the daily positional uncertainties of organ motion and set-up error. However, it is shown in this paper that the calculation should take into account the beam configuration of the treatment plan. In a typical coplanar multibeam plan, usually in the transverse plane, any given edge of the target volume is normally defined by a single beam or two parallel and opposed beams. However, because of the presence of the other beams, the effect of the blurring of the edge-defining beam(s) is reduced, which changes the value of the required margin to beta (sigma - sigmap) where, for example, beta can be as low as 1.04 in the transverse plane of a three-beam plan. The width of the required margins is calculated for up to six beams and presented in a table. It is shown that, while the table was derived using an idealized plan of equally weighted plane beams irradiating a spherical target, it is also valid for non-uniform beam weightings, wedged-beam plans, target volumes of general shape and intensity-modulated radiotherapy (IMRT).
Full text links
Related Resources
Trending Papers
Heart failure with preserved ejection fraction: diagnosis, risk assessment, and treatment.Clinical Research in Cardiology : Official Journal of the German Cardiac Society 2024 April 12
Proximal versus distal diuretics in congestive heart failure.Nephrology, Dialysis, Transplantation 2024 Februrary 30
World Health Organization and International Consensus Classification of eosinophilic disorders: 2024 update on diagnosis, risk stratification, and management.American Journal of Hematology 2024 March 30
Efficacy and safety of pharmacotherapy in chronic insomnia: A review of clinical guidelines and case reports.Mental Health Clinician 2023 October
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app