Phillip Prior1, An Tai1, Beth Erickson1, X Allen Li2. 1. Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin. 2. Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin. Electronic address: ali@mcw.edu.
Abstract
PURPOSE: To consolidate duodenum and small bowel toxicity data from clinical studies with different dose fractionation schedules using the modified linear quadratic (MLQ) model. A methodology of adjusting the dose-volume (D,v) parameters to different levels of normal tissue complication probability (NTCP) was presented. METHODS AND MATERIALS: A set of NTCP model parameters for duodenum toxicity were estimated by the χ(2) fitting method using literature-based tolerance dose and generalized equivalent uniform dose (gEUD) data. These model parameters were then used to convert (D,v) data into the isoeffective dose in 2 Gy per fraction, (D(MLQED2),v) and convert these parameters to an isoeffective dose at another NTCP (D(MLQED2'),v). RESULTS: The literature search yielded 5 reports useful in making estimates of duodenum and small bowel toxicity. The NTCP model parameters were found to be TD50(1)(model) = 60.9 ± 7.9 Gy, m = 0.21 ± 0.05, and δ = 0.09 ± 0.03 Gy(-1). Isoeffective dose calculations and toxicity rates associated with hypofractionated radiation therapy reports were found to be consistent with clinical data having different fractionation schedules. Values of (D(MLQED2'),v) between different NTCP levels remain consistent over a range of 5%-20%. CONCLUSIONS: MLQ-based isoeffective calculations of dose-response data corresponding to grade ≥2 duodenum toxicity were found to be consistent with one another within the calculation uncertainty. The (D(MLQED2),v) data could be used to determine duodenum and small bowel dose-volume constraints for new dose escalation strategies.
PURPOSE: To consolidate duodenum and small bowel toxicity data from clinical studies with different dose fractionation schedules using the modified linear quadratic (MLQ) model. A methodology of adjusting the dose-volume (D,v) parameters to different levels of normal tissue complication probability (NTCP) was presented. METHODS AND MATERIALS: A set of NTCP model parameters for duodenum toxicity were estimated by the χ(2) fitting method using literature-based tolerance dose and generalized equivalent uniform dose (gEUD) data. These model parameters were then used to convert (D,v) data into the isoeffective dose in 2 Gy per fraction, (D(MLQED2),v) and convert these parameters to an isoeffective dose at another NTCP (D(MLQED2'),v). RESULTS: The literature search yielded 5 reports useful in making estimates of duodenum and small bowel toxicity. The NTCP model parameters were found to be TD50(1)(model) = 60.9 ± 7.9 Gy, m = 0.21 ± 0.05, and δ = 0.09 ± 0.03 Gy(-1). Isoeffective dose calculations and toxicity rates associated with hypofractionated radiation therapy reports were found to be consistent with clinical data having different fractionation schedules. Values of (D(MLQED2'),v) between different NTCP levels remain consistent over a range of 5%-20%. CONCLUSIONS: MLQ-based isoeffective calculations of dose-response data corresponding to grade ≥2 duodenum toxicity were found to be consistent with one another within the calculation uncertainty. The (D(MLQED2),v) data could be used to determine duodenum and small bowel dose-volume constraints for new dose escalation strategies.
Authors: Daniel L P Holyoake; Marianne Aznar; Somnath Mukherjee; Mike Partridge; Maria A Hawkins Journal: Radiother Oncol Date: 2017-06-06 Impact factor: 6.280