A new variable for SRS plan quality evaluation based on normal tissue sparing

The effect of prescription isodose levels

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Objective: A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.

Methods: 40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing.

Results: Among all plans, the DDS was found to be the lowest for the prescription at 90% IDL and the highest for the prescription at 60% or 70%. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings.

Conclusion: A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60% and 70% IDLs were found to provide best normal tissue sparing.

Advances in knowledge: A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.

Original languageEnglish (US)
Article number20140362
JournalBritish Journal of Radiology
Volume87
Issue number1043
DOIs
StatePublished - Nov 1 2014

Fingerprint

Radiosurgery
Prescriptions

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

@article{9c0b1aa134e3425da3126fc96144924d,
title = "A new variable for SRS plan quality evaluation based on normal tissue sparing: The effect of prescription isodose levels",
abstract = "Objective: A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.Methods: 40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50{\%} to 90{\%} in 10{\%} increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing.Results: Among all plans, the DDS was found to be the lowest for the prescription at 90{\%} IDL and the highest for the prescription at 60{\%} or 70{\%}. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings.Conclusion: A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60{\%} and 70{\%} IDLs were found to provide best normal tissue sparing.Advances in knowledge: A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.",
author = "Q. Zhang and Dandan Zheng and Y. Lei and B. Morgan and J. Driewer and M. Zhang and Sicong Li and Sumin Zhou and Weining Zhen and Thompson, {Robert Bruce} and Wahl, {Andrew O} and Chi Lin and Enke, {Charles Arthur}",
year = "2014",
month = "11",
day = "1",
doi = "10.1259/bjr.20140362",
language = "English (US)",
volume = "87",
journal = "British Journal of Radiology",
issn = "0007-1285",
publisher = "British Institute of Radiology",
number = "1043",

}

TY - JOUR

T1 - A new variable for SRS plan quality evaluation based on normal tissue sparing

T2 - The effect of prescription isodose levels

AU - Zhang, Q.

AU - Zheng, Dandan

AU - Lei, Y.

AU - Morgan, B.

AU - Driewer, J.

AU - Zhang, M.

AU - Li, Sicong

AU - Zhou, Sumin

AU - Zhen, Weining

AU - Thompson, Robert Bruce

AU - Wahl, Andrew O

AU - Lin, Chi

AU - Enke, Charles Arthur

PY - 2014/11/1

Y1 - 2014/11/1

N2 - Objective: A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.Methods: 40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing.Results: Among all plans, the DDS was found to be the lowest for the prescription at 90% IDL and the highest for the prescription at 60% or 70%. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings.Conclusion: A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60% and 70% IDLs were found to provide best normal tissue sparing.Advances in knowledge: A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.

AB - Objective: A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.Methods: 40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing.Results: Among all plans, the DDS was found to be the lowest for the prescription at 90% IDL and the highest for the prescription at 60% or 70%. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings.Conclusion: A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60% and 70% IDLs were found to provide best normal tissue sparing.Advances in knowledge: A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.

UR - http://www.scopus.com/inward/record.url?scp=84908688782&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84908688782&partnerID=8YFLogxK

U2 - 10.1259/bjr.20140362

DO - 10.1259/bjr.20140362

M3 - Article

VL - 87

JO - British Journal of Radiology

JF - British Journal of Radiology

SN - 0007-1285

IS - 1043

M1 - 20140362

ER -