TY - JOUR
T1 - Impact of the high-definition multileaf collimator on linear accelerator-based intracranial stereotactic radiosurgery
AU - Tanyi, J. A.
AU - Kato, C. M.
AU - Chen, Y.
AU - Chen, Z.
AU - Fuss, M.
PY - 2011/7
Y1 - 2011/7
N2 - Objectives: The impact of two multileaf collimator (MLC) systems for linear accelerator-based intracranial stereotactic radiosurgery (SRS) was assessed. Methods: 68 lesions formed the basis of this study. 2.5 mm leaf width plans served as reference. Comparative plans, with identical planning parameters, were based on a 5 mm leaf width MLC system. Two collimation strategies, with collimation fixed at 0° or 90° and optimised per arc or beam, were also assessed. Dose computation was based on the pencil beam algorithm with allowance for tissue heterogeneity. Plan normalisation was such that 100% of the prescription dose covered 95% of the planning target volume. Plan evaluation was based on target coverage and normal tissue avoidance criteria. Results: The median conformity index difference between the MLC systems ranged between 0.8% and 14.2%; the 2.5 mm MLC exhibited better dose conformation. The median reduction of normal tissue exposed to ≥100%, ≥50% and ≥25% of the prescription dose ranged from 13.4% to 29.7%, favouring the 2.5 mm MLC system. Dose fall-off was steeper for the 2.5 mm MLC system with an overall median absolute difference ranging from 0.4 to 1.2 mm. The use of collimation optimisation resulted in a decrease in differences between the MLC systems. The results demonstrated the dosimetric merit of the 2.5 mm leaf width MLC system over the 5 mm leaf width system, albeit small, for the investigated range of intracranial SRS targets. Conclusion: The clinical significance of these results warrants further investigation to determine whether the observed dosimetric advantages translate into outcome improvements.
AB - Objectives: The impact of two multileaf collimator (MLC) systems for linear accelerator-based intracranial stereotactic radiosurgery (SRS) was assessed. Methods: 68 lesions formed the basis of this study. 2.5 mm leaf width plans served as reference. Comparative plans, with identical planning parameters, were based on a 5 mm leaf width MLC system. Two collimation strategies, with collimation fixed at 0° or 90° and optimised per arc or beam, were also assessed. Dose computation was based on the pencil beam algorithm with allowance for tissue heterogeneity. Plan normalisation was such that 100% of the prescription dose covered 95% of the planning target volume. Plan evaluation was based on target coverage and normal tissue avoidance criteria. Results: The median conformity index difference between the MLC systems ranged between 0.8% and 14.2%; the 2.5 mm MLC exhibited better dose conformation. The median reduction of normal tissue exposed to ≥100%, ≥50% and ≥25% of the prescription dose ranged from 13.4% to 29.7%, favouring the 2.5 mm MLC system. Dose fall-off was steeper for the 2.5 mm MLC system with an overall median absolute difference ranging from 0.4 to 1.2 mm. The use of collimation optimisation resulted in a decrease in differences between the MLC systems. The results demonstrated the dosimetric merit of the 2.5 mm leaf width MLC system over the 5 mm leaf width system, albeit small, for the investigated range of intracranial SRS targets. Conclusion: The clinical significance of these results warrants further investigation to determine whether the observed dosimetric advantages translate into outcome improvements.
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U2 - 10.1259/bjr/19726857
DO - 10.1259/bjr/19726857
M3 - Article
C2 - 20923911
AN - SCOPUS:79959620158
SN - 0007-1285
VL - 84
SP - 629
EP - 638
JO - British Journal of Radiology
JF - British Journal of Radiology
IS - 1003
ER -