PURPOSE: Intraoperative radiation therapy (IORT) with low-energy x-rays is used to treat the tumor bed during breast-conserving surgery. The purpose was to determine the relative biologic effectiveness (RBE) of 50-kV x-rays for inactivation of cells irradiated in a tumor-bed phantom. METHODS AND MATERIALS: The RBE was determined for clonogenic inactivation of human tumor and normal cells (MCF7, human umbilical vein endothelial cells, normal skin fibroblasts), and hamster V79 cells. The 50-kV x-rays from the Intrabeam machine (Carl Zeiss Surgical) with a spherical 4-cm applicator were used. Cells were irradiated in a water-equivalent phantom at defined distances (8.1-22.9 mm) from the applicator surface. The 50-kV x-rays from a surface therapy machine (Dermopan, Siemens) were included for comparison; 6-MV x-rays were used as reference radiation. RESULTS: At 8.1-mm depth in the phantom (dose rate 15.1 Gy/h), mean RBE values of 50-kV x-rays from Intrabeam were 1.26 to 1.42 for the 4 cell types at doses yielding surviving fractions in the range of 0.01 to 0.5. Confidence intervals were in the range of 1.2 and 1.5. Similar RBE values were found for 50-kV x-rays from Dermopan for V79 (1.30, CI 1.25-1.36, P=.74) and GS4 (1.42, CI 1.30-1.54, P=.67). No significant dependence of RBE on dose was found for Intrabeam, but RBE decreased at a larger distance (12.7 mm; 9.8 Gy/h). CONCLUSIONS: An increased clinically relevant RBE was found for cell irradiation with Intrabeam at depths in the tumor bed targeted by IORT. The reduced RBE values at larger distances may be related to increased repair of sublethal damage during protracted irradiation or to hardening of the photon beam energy.
PURPOSE: Intraoperative radiation therapy (IORT) with low-energy x-rays is used to treat the tumor bed during breast-conserving surgery. The purpose was to determine the relative biologic effectiveness (RBE) of 50-kV x-rays for inactivation of cells irradiated in a tumor-bed phantom. METHODS AND MATERIALS: The RBE was determined for clonogenic inactivation of humantumor and normal cells (MCF7, human umbilical vein endothelial cells, normal skin fibroblasts), and hamster V79 cells. The 50-kV x-rays from the Intrabeam machine (Carl Zeiss Surgical) with a spherical 4-cm applicator were used. Cells were irradiated in a water-equivalent phantom at defined distances (8.1-22.9 mm) from the applicator surface. The 50-kV x-rays from a surface therapy machine (Dermopan, Siemens) were included for comparison; 6-MV x-rays were used as reference radiation. RESULTS: At 8.1-mm depth in the phantom (dose rate 15.1 Gy/h), mean RBE values of 50-kV x-rays from Intrabeam were 1.26 to 1.42 for the 4 cell types at doses yielding surviving fractions in the range of 0.01 to 0.5. Confidence intervals were in the range of 1.2 and 1.5. Similar RBE values were found for 50-kV x-rays from Dermopan for V79 (1.30, CI 1.25-1.36, P=.74) and GS4 (1.42, CI 1.30-1.54, P=.67). No significant dependence of RBE on dose was found for Intrabeam, but RBE decreased at a larger distance (12.7 mm; 9.8 Gy/h). CONCLUSIONS: An increased clinically relevant RBE was found for cell irradiation with Intrabeam at depths in the tumor bed targeted by IORT. The reduced RBE values at larger distances may be related to increased repair of sublethal damage during protracted irradiation or to hardening of the photon beam energy.
Authors: Caroline Steenken; Jens Fleckenstein; Stefan Kegel; Lennart Jahnke; Anna Simeonova; Linda Hartmann; Jens Kübler; Marlon R Veldwijk; Frederik Wenz; Carsten Herskind; Frank Anton Giordano Journal: Strahlenther Onkol Date: 2015-03-13 Impact factor: 3.621
Authors: John A Vargo; Kristie M Sparks; Rahul Singh; Geraldine M Jacobson; Joshua D Hack; Christopher P Cifarelli Journal: J Neurooncol Date: 2018-08-09 Impact factor: 4.130
Authors: Basem A Dahshan; Joshua S Weir; Robert P Bice; Paul Renz; Daniel T Cifarelli; Linda Poplawski; Joshua Hack; John A Vargo; Christopher P Cifarelli Journal: Brachytherapy Date: 2021-01-14 Impact factor: 2.362
Authors: Christoph Weigel; Marlon R Veldwijk; Christopher C Oakes; Petra Seibold; Alla Slynko; David B Liesenfeld; Mariona Rabionet; Sabrina A Hanke; Frederik Wenz; Elena Sperk; Axel Benner; Christoph Rösli; Roger Sandhoff; Yassen Assenov; Christoph Plass; Carsten Herskind; Jenny Chang-Claude; Peter Schmezer; Odilia Popanda Journal: Nat Commun Date: 2016-03-11 Impact factor: 14.919
Authors: Jens Kübler; Stefanie Kirschner; Linda Hartmann; Grit Welzel; Maren Engelhardt; Carsten Herskind; Marlon R Veldwijk; Christian Schultz; Manuela Felix; Gerhard Glatting; Patrick Maier; Frederik Wenz; Marc A Brockmann; Frank A Giordano Journal: Oncotarget Date: 2016-07-19
Authors: Roxana Cristina Popescu; Diana Iulia Savu; Miriam Bierbaum; Adriana Grbenicek; Frank Schneider; Hiltraud Hosser; Bogdan Ștefan Vasile; Ecaterina Andronescu; Frederik Wenz; Frank A Giordano; Carsten Herskind; Marlon R Veldwijk Journal: Int J Mol Sci Date: 2021-06-24 Impact factor: 5.923