What do Dosimetric Errors Encountered in Prostate Implant Brachytherapy tell us about ÃÂ±/ÃÂ²?Paul Mobit1,3*, Ephraim Agyingi2, Satyaseelan Packianathan1 and Claus Chunli Yang1
- *Corresponding Author:
- Paul Mobit
Department of Radiation Oncology
University of Mississippi Medical Center
350 West Woodrow Wilson
Dr, Jackson, MS 39213, USA
Tel: 001 601 815 6930
E-mail: [email protected]
Received date: January 06, 2015, Accepted date: February 13, 2015, Publication February 17, 2015
Citation: Mobit P, Agyingi E, Packianathan S, Yang CC (2015) What do Dosimetric Errors Encountered in Prostate Implant Brachytherapy tell us about α/β?. J Nucl Med Radiat Ther 6:214. doi:10.4172/2155-9619.1000214
Copyright: © 2015 Mobit P, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Objective: To determine the α/β ratio of prostate cancer using the linear quadratic model taking into account different radiation prescription doses and RBE for low energy gamma rays.
Methods and material: The linear quadratic model was used to evaluate the α/β ratio for prostate cancer taking into account the dosimetric errors resulting from seed displacements in prostate permanent implant brachytherapy with 125I and 103Pd. The study assessed the variability of the α/β ratio with different prescribed external beam radiation therapy doses and published values of the relative biological effectiveness (RBE) for both 125I and 103Pd. The biological effective dose (BED) for prostate implant brachytherapy was equated to the external beam radiation therapy dose to derive an equation for α/β ratio.
Results: The results showed that the α/β ratio for prostate cancer varied between 1 and 4.5 for an RBE of 1.0 when an external beam dose of 78.0 Gy was prescribed. When published values of RBEs were incorporated into the analysis, the α/β ratio varied between 0.37 and 4.4. The α/β ratio changed by 30% when the external beam radiation dose was increased from 72 Gy to 80 Gy.
Conclusions: Assuming an average reduction in implanted seeds brachytherapy dose between 10–20% using 125I or 103Pd, the realistic value of the α/β ratio for prostate tumors likely lies between 0.7 and 2.0.