Kengo Ogura1, Yasuhiro Kosaka2, Toshiyuki Imagumbai2, Kazuhito Ueki2, Ryo Narukami2, Takayuki Hattori2, Masaki Kokubo2. 1. Department of Radiation Oncology, Kobe City Medical Center General Hospital, 2-1-1 Minatojima-Minamimachi Chuo-ku, Kobe, 6500047, Japan. oguken@kuhp.kyoto-u.ac.jp. 2. Department of Radiation Oncology, Kobe City Medical Center General Hospital, 2-1-1 Minatojima-Minamimachi Chuo-ku, Kobe, 6500047, Japan.
Abstract
PURPOSE: When treating large metastatic brain tumors with stereotactic radiotherapy (SRT), high dose conformity to target is difficult to achieve. Employing a modified planning target volume (mPTV) instead of the original PTV may be one way to improve the dose distribution in linear accelerator-based SRT using a dynamic conformal technique. In this study, we quantitatively analyzed the impact of a mPTV on dose distribution. MATERIALS AND METHODS: Twenty-four tumors with a maximum diameter of >2 cm were collected. For each tumor, two plans were created: one used a mPTV and the other did not. The mPTV was produced by shrinking or enlarging the original PTV according to the dose distribution in the original plan. The dose conformity was evaluated and compared between the plans using a two-sided paired t test. RESULTS: The conformity index defined by the Radiation Therapy Oncology Group was 1.34 ± 0.10 and 1.41 ± 0.13, and Paddick's conformity index was 0.75 ± 0.05 and 0.71 ± 0.06, for the plans with and without a mPTV, respectively. All of these improvements were statistically significant (P < 0.05). CONCLUSION: The use of a mPTV can improve target conformity when planning SRT for large metastatic brain tumors.
PURPOSE: When treating large metastatic brain tumors with stereotactic radiotherapy (SRT), high dose conformity to target is difficult to achieve. Employing a modified planning target volume (mPTV) instead of the original PTV may be one way to improve the dose distribution in linear accelerator-based SRT using a dynamic conformal technique. In this study, we quantitatively analyzed the impact of a mPTV on dose distribution. MATERIALS AND METHODS: Twenty-four tumors with a maximum diameter of >2 cm were collected. For each tumor, two plans were created: one used a mPTV and the other did not. The mPTV was produced by shrinking or enlarging the original PTV according to the dose distribution in the original plan. The dose conformity was evaluated and compared between the plans using a two-sided paired t test. RESULTS: The conformity index defined by the Radiation Therapy Oncology Group was 1.34 ± 0.10 and 1.41 ± 0.13, and Paddick's conformity index was 0.75 ± 0.05 and 0.71 ± 0.06, for the plans with and without a mPTV, respectively. All of these improvements were statistically significant (P < 0.05). CONCLUSION: The use of a mPTV can improve target conformity when planning SRT for large metastatic brain tumors.
Authors: E Shaw; C Scott; L Souhami; R Dinapoli; R Kline; J Loeffler; N Farnan Journal: Int J Radiat Oncol Biol Phys Date: 2000-05-01 Impact factor: 7.038
Authors: E Shaw; R Kline; M Gillin; L Souhami; A Hirschfeld; R Dinapoli; L Martin Journal: Int J Radiat Oncol Biol Phys Date: 1993-12-01 Impact factor: 7.038
Authors: Mark E Linskey; David W Andrews; Anthony L Asher; Stuart H Burri; Douglas Kondziolka; Paula D Robinson; Mario Ammirati; Charles S Cobbs; Laurie E Gaspar; Jay S Loeffler; Michael McDermott; Minesh P Mehta; Tom Mikkelsen; Jeffrey J Olson; Nina A Paleologos; Roy A Patchell; Timothy C Ryken; Steven N Kalkanis Journal: J Neurooncol Date: 2009-12-04 Impact factor: 4.130