Compatibility of the Linear-Quadratic Formalism and Biologically Effective Dose Concept to High-Dose-Per-Fraction Irradiation in a Murine Tumor

2011 ◽  
Vol 81 (5) ◽  
pp. 1538-1543 ◽  
Author(s):  
Shinya Otsuka ◽  
Yuta Shibamoto ◽  
Hiromitsu Iwata ◽  
Rumi Murata ◽  
Chikao Sugie ◽  
...  
Keyword(s):  
Effective Dose ◽  
High Dose ◽  
Biologically Effective Dose ◽  
Linear Quadratic ◽  
Murine Tumor ◽  
Quadratic Formalism ◽  
Dose Per Fraction

Biologically effective dose distribution based on the linear quadratic model and its clinical relevance

1995 ◽  
Vol 33 (2) ◽  
pp. 375-389 ◽  
Author(s):  
Steve P. Lee ◽  
Min Y. Leu ◽  
James B. Smathers ◽  
William H. McBride ◽  
Robert G. Parker ◽  
...  
Keyword(s):  
Effective Dose ◽  
Dose Distribution ◽  
Clinical Relevance ◽  
Quadratic Model ◽  
Biologically Effective Dose ◽  
Linear Quadratic ◽  
Linear Quadratic Model

scholarly journals The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

2016 ◽  
Vol 125 (Supplement_1) ◽  
pp. 154-159 ◽  
Author(s):  
Benjamin H. Kann ◽  
James B. Yu ◽  
John M. Stahl ◽  
James E. Bond ◽  
Christopher Loiselle ◽  
...  
Keyword(s):  
Effective Dose ◽  
Dose Rate ◽  
Gamma Knife ◽  
Treatment Time ◽  
Gamma Knife Radiosurgery ◽  
High Dose ◽  
Biologically Effective Dose ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
Dose Rates

OBJECTIVEFunctional Gamma Knife radiosurgery (GKRS) procedures have been increasingly used for treating patients with tremor, trigeminal neuralgia (TN), and refractory obsessive-compulsive disorder. Although its rates of toxicity are low, GKRS has been associated with some, if low, risks for serious sequelae, including hemiparesis and even death. Anecdotal reports have suggested that even with a standardized prescription dose, rates of functional GKRS toxicity increase after replacement of an old cobalt-60 source with a new source. Dose rate changes over the course of the useful lifespan of cobalt-60 are not routinely considered in the study of patients treated with functional GKRS, but these changes may be associated with significant variation in the biologically effective dose (BED) delivered to neural tissue.METHODSThe authors constructed a linear-quadratic model of BED in functional GKRS with a dose-protraction factor to correct for intrafraction DNA-damage repair and used standard single-fraction doses for trigeminal nerve ablation for TN (85 Gy), thalamotomy for tremor (130 Gy), and capsulotomy for obsessive-compulsive disorder (180 Gy). Dose rate and treatment time for functional GKRS involving 4-mm collimators were derived from calibrations in the authors' department and from the cobalt-60 decay rate. Biologically plausible values for the ratio for radiosensitivity to fraction size (α/β) and double-strand break (DSB) DNA repair halftimes (τ) were estimated from published experimental data. The biphasic characteristics of DSB repair in normal tissue were accounted for in deriving an effective τ1 halftime (fast repair) and τ2 halftime (slow repair). A sensitivity analysis was performed with a range of plausible parameter values.RESULTSAfter replacement of the cobalt-60 source, the functional GKRS dose rate rose from 1.48 to 2.99 Gy/min, treatment time fell, and estimated BED increased. Assuming the most biologically plausible parameters, source replacement resulted in an immediate relative BED increase of 11.7% for GKRS-based TN management with 85 Gy, 15.6% for thalamotomy with 130 Gy, and 18.6% for capsulotomy with 180 Gy. Over the course of the 63-month lifespan of the cobalt-60 source, BED decreased annually by 2.2% for TN management, 3.0% for thalamotomy, and 3.5% for capsulotomy.CONCLUSIONSUse of a new cobalt-60 source after replacement of an old source substantially increases the predicted BED for functional GKRS treatments for the same physical dose prescription. Source age, dose rate, and treatment time should be considered in the study of outcomes after high-dose functional GKRS treatments. Animal and clinical studies are needed to determine how this potential change in BED contributes to GKRS toxicity and whether technical adjustments should be made to reduce dose rates or prescription doses with newer cobalt-60 sources.

The linear-quadratic model is inappropriate to model high dose per fraction effects in radiosurgery

2009 ◽  
Vol 36 (8) ◽  
pp. 3381-3384 ◽  
Author(s):  
John P. Kirkpatrick ◽  
David J. Brenner ◽  
Colin G. Orton
Keyword(s):  
Quadratic Model ◽  
High Dose ◽  
Linear Quadratic ◽  
Linear Quadratic Model ◽  
Dose Per Fraction

PO-0941 INADEQUACY OF USING THE LINEAR-QUADRATIC MODEL IN HIGH-DOSE-PER-FRACTION RADIOTHERAPY: IN VITRO AND IN VIVO STUDY

2012 ◽  
Vol 103 ◽  
pp. S371
Author(s):  
Y. Shibamoto ◽  
S. Otsuka ◽  
H. Iwata ◽  
A. Miyakawa ◽  
C. Sugie ◽  
...  
Keyword(s):  
In Vivo Study ◽  
Quadratic Model ◽  
High Dose ◽  
Linear Quadratic ◽  
Linear Quadratic Model ◽  
Dose Per Fraction
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