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Schell, M.C., Bova, F.J., Larson, D.A., Leavitt, D.D., Lutz, W.R., Podgorsak, E.B. and Wu, A. (1995) Stereotactic Radiosurgery: Report of Task Group 42, AAPM Radiation Therapy Committee American Institute of Physics, Woodbury.
https://doi.org/10.37206/53

has been cited by the following article:

• TITLE: A Statistical Index for Evaluating the CTV Coverage Loss of Brain Stereotactic Radiosurgery When the PTV Margin Is Zero

  AUTHORS: Jenghwa Chang

  KEYWORDS: Stereotactic Radiosurgery, PTV Margin, Coverage Probability

  JOURNAL NAME: International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, Vol.11 No.1, February 28, 2022

  ABSTRACT: Purpose: To develop a new statistical index “percent CTV (clinical target vo-lume) coverage probability” (%CCP), defined as the probability that a specific percent (e.g., 95%) of the CTV can be reliably covered by the prescription dose, for evaluating the coverage loss of brain (fractionated) stereotactic radiosurgery (SRS/fSRS) when the PTV (planning target volume) margin is zero. Methods: The random variable Q for CTV percent coverage was derived using a previously developed model for CTV random motion that follows a three-dimensional (3D) independent normal distribution with a zero mean and a standard deviation of ????(for translation) or ????(for rotation). Assuming both CTV and PTV are spherical with the same diameter dCTV, the cumulative distribution function of Q could be obtained analytically using the relation of sphere-sphere intersection. The %CCP was then derived as the reliability function of Q and was used to quantify the coverage loss for selected dCTV. Results: The 95%-95% clinical goal (95% of the times, at least 95% of the CTV is covered) is not achievable with dCTV mm. For common CTVs (dCTV mm) encountered in SRS/fSRS, only 60%-90% of the CTV could be reliably covered by the prescription dose 95% of the time. For ????=0.5mm and ???? =0.4?, the 95% CCP was the highest when the distance between the CTV and the isocenter ???????=0 and gradually decreased with the increasing ???????. Conclusions: The %CCP was successfully derived for evaluating the CTV coverage loss for brain SRS/fSRS. When the PTV margin is zero, the 95%-95% clinical goal cannot be achieved for most targets (dCTV mm).