Assessing small-volume spinal cord dose for repeat spinal stereotactic body radiotherapy treatments

Lijun Ma, Neil Kirby, Renee Korol, David A. Larson, Arjun Sahgal

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Spinal cord biologically effective dose (BED) limits are critical to safe spine stereotactic body radiotherapy (SBRT) delivery. In particular, when repeating SBRT to the same site, the problem of adding non-uniform BED distributions within small volumes of spinal cord has yet to be solved. We report a probability-based generalized BED (gBED) model to guide repeat spine SBRT treatment planning. The gBED was formulated by considering the sequential damaging probabilities of repeat spine SBRT treatments. Parameters from the standard linear-quadratic model, such as α/β = 2 Gy for the spinal cord, were applied. We tested the model based on SBRT specific spinal cord tolerance using a simulated and ten clinical repeat SBRT cases. The gBED provides a consistent solution for superimposing non-uniform dose distributions from different fractionation schemes, analogous to the BED for uniform dose distributions. Based on ten clinical cases, the gBED was observed to eliminate discrepancies in the cumulative BED of approximately 5% to 20% within small volumes (e.g. 0.1-2.0 cc) of spinal cord, as compared to a conventional calculation method. When assessing spinal cord tolerance for repeat spinal SBRT treatments, caution should be exercised when applying conventional BED calculations for small volumes of spinal cord irradiated, and the gBED potentially provides more conservative and consistently derived dose surrogates to guide safe treatment planning and treatment outcome modeling.

Original languageEnglish (US)
Article number7843
JournalPhysics in Medicine and Biology
Volume57
Issue number23
DOIs
StatePublished - Dec 7 2012
Externally publishedYes

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Radiosurgery
Spinal Cord
Spine
Therapeutics
Linear Models

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

Assessing small-volume spinal cord dose for repeat spinal stereotactic body radiotherapy treatments. / Ma, Lijun; Kirby, Neil; Korol, Renee; Larson, David A.; Sahgal, Arjun.

In: Physics in Medicine and Biology, Vol. 57, No. 23, 7843, 07.12.2012.

Research output: Contribution to journalArticle

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