Spine stereotactic body radiation therapy plans: Achieving dose coverage, conformity, and dose falloff

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Abstract

We report our experience of establishing planning objectives to achieve dose coverage, conformity, and dose falloff for spine stereotactic body radiation therapy (SBRT) plans. Patients with spine lesions were treated using SBRT in our institution since September 2009. Since September 2011, we established the following planning objectives for our SBRT spine plans in addition to the cord dose constraints: (1) dose coverage-prescription dose (PD) to cover at least 95% planning target volume (PTV) and 90% PD to cover at least 99% PTV; (2) conformity index (CI)-ratio of prescription isodose volume (PIV) to the PTV < 1.2; (3) dose falloff-ratio of 50% PIV to the PTV (R<inf>50%</inf>); (4) and maximum dose in percentage of PD at 2cm from PTV in any direction (D<inf>2cm</inf>) to follow Radiation Therapy Oncology Group (RTOG) 0915. We have retrospectively reviewed 66 separate spine lesions treated between September 2009 and December 2012 (31 treated before September 2011 [group 1] and 35 treated after [group 2]). The χ<sup>2</sup> test was used to examine the difference in parameters between groups. The PTV V<inf>100% PD</inf> ≥ 95% objective was met in 29.0% of group 1 vs 91.4% of group 2 (p < 0.01) plans. The PTV V<inf>90% PD</inf> ≥ 99% objective was met in 38.7% of group 1 vs 88.6% of group 2 (p < 0.01) plans. Overall, 4 plans in group 1 had CI > 1.2 vs none in group 2 (p = 0.04). For D<inf>2cm</inf>, 48.3% plans yielded a minor violation of the objectives and 16.1% a major violation for group 1, whereas 17.1% exhibited a minor violation and 2.9% a major violation for group 2 (p < 0.01). Spine SBRT plans can be improved on dose coverage, conformity, and dose falloff employing a combination of RTOG spine and lung SBRT protocol planning objectives.

Original languageEnglish (US)
Pages (from-to)181-185
Number of pages5
JournalMedical Dosimetry
Volume40
Issue number3
DOIs
StatePublished - Feb 3 2015

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Spine
Radiotherapy
Prescriptions
Radiation Oncology
Lung

Keywords

  • Spine SBRT plans

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

@article{fd23d9d3677948f49886f7e2de116867,
title = "Spine stereotactic body radiation therapy plans: Achieving dose coverage, conformity, and dose falloff",
abstract = "We report our experience of establishing planning objectives to achieve dose coverage, conformity, and dose falloff for spine stereotactic body radiation therapy (SBRT) plans. Patients with spine lesions were treated using SBRT in our institution since September 2009. Since September 2011, we established the following planning objectives for our SBRT spine plans in addition to the cord dose constraints: (1) dose coverage-prescription dose (PD) to cover at least 95{\%} planning target volume (PTV) and 90{\%} PD to cover at least 99{\%} PTV; (2) conformity index (CI)-ratio of prescription isodose volume (PIV) to the PTV < 1.2; (3) dose falloff-ratio of 50{\%} PIV to the PTV (R50{\%}); (4) and maximum dose in percentage of PD at 2cm from PTV in any direction (D2cm) to follow Radiation Therapy Oncology Group (RTOG) 0915. We have retrospectively reviewed 66 separate spine lesions treated between September 2009 and December 2012 (31 treated before September 2011 [group 1] and 35 treated after [group 2]). The χ2 test was used to examine the difference in parameters between groups. The PTV V100{\%} PD ≥ 95{\%} objective was met in 29.0{\%} of group 1 vs 91.4{\%} of group 2 (p < 0.01) plans. The PTV V90{\%} PD ≥ 99{\%} objective was met in 38.7{\%} of group 1 vs 88.6{\%} of group 2 (p < 0.01) plans. Overall, 4 plans in group 1 had CI > 1.2 vs none in group 2 (p = 0.04). For D2cm, 48.3{\%} plans yielded a minor violation of the objectives and 16.1{\%} a major violation for group 1, whereas 17.1{\%} exhibited a minor violation and 2.9{\%} a major violation for group 2 (p < 0.01). Spine SBRT plans can be improved on dose coverage, conformity, and dose falloff employing a combination of RTOG spine and lung SBRT protocol planning objectives.",
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author = "Hong, {Linda X.} and Shankar Viswanathan and Jin Shen and Hsiang-Chi Kuo and Dinesh Mynampati and Ravindra Yaparpalvi and Lee Goddard and Amar Basavatia and Fox, {Jana L.} and Garg, {Madhur K.} and Shalom Kalnicki and Tome, {Wolfgang A.}",
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T1 - Spine stereotactic body radiation therapy plans

T2 - Achieving dose coverage, conformity, and dose falloff

AU - Hong, Linda X.

AU - Viswanathan, Shankar

AU - Shen, Jin

AU - Kuo, Hsiang-Chi

AU - Mynampati, Dinesh

AU - Yaparpalvi, Ravindra

AU - Goddard, Lee

AU - Basavatia, Amar

AU - Fox, Jana L.

AU - Garg, Madhur K.

AU - Kalnicki, Shalom

AU - Tome, Wolfgang A.

PY - 2015/2/3

Y1 - 2015/2/3

N2 - We report our experience of establishing planning objectives to achieve dose coverage, conformity, and dose falloff for spine stereotactic body radiation therapy (SBRT) plans. Patients with spine lesions were treated using SBRT in our institution since September 2009. Since September 2011, we established the following planning objectives for our SBRT spine plans in addition to the cord dose constraints: (1) dose coverage-prescription dose (PD) to cover at least 95% planning target volume (PTV) and 90% PD to cover at least 99% PTV; (2) conformity index (CI)-ratio of prescription isodose volume (PIV) to the PTV < 1.2; (3) dose falloff-ratio of 50% PIV to the PTV (R50%); (4) and maximum dose in percentage of PD at 2cm from PTV in any direction (D2cm) to follow Radiation Therapy Oncology Group (RTOG) 0915. We have retrospectively reviewed 66 separate spine lesions treated between September 2009 and December 2012 (31 treated before September 2011 [group 1] and 35 treated after [group 2]). The χ2 test was used to examine the difference in parameters between groups. The PTV V100% PD ≥ 95% objective was met in 29.0% of group 1 vs 91.4% of group 2 (p < 0.01) plans. The PTV V90% PD ≥ 99% objective was met in 38.7% of group 1 vs 88.6% of group 2 (p < 0.01) plans. Overall, 4 plans in group 1 had CI > 1.2 vs none in group 2 (p = 0.04). For D2cm, 48.3% plans yielded a minor violation of the objectives and 16.1% a major violation for group 1, whereas 17.1% exhibited a minor violation and 2.9% a major violation for group 2 (p < 0.01). Spine SBRT plans can be improved on dose coverage, conformity, and dose falloff employing a combination of RTOG spine and lung SBRT protocol planning objectives.

AB - We report our experience of establishing planning objectives to achieve dose coverage, conformity, and dose falloff for spine stereotactic body radiation therapy (SBRT) plans. Patients with spine lesions were treated using SBRT in our institution since September 2009. Since September 2011, we established the following planning objectives for our SBRT spine plans in addition to the cord dose constraints: (1) dose coverage-prescription dose (PD) to cover at least 95% planning target volume (PTV) and 90% PD to cover at least 99% PTV; (2) conformity index (CI)-ratio of prescription isodose volume (PIV) to the PTV < 1.2; (3) dose falloff-ratio of 50% PIV to the PTV (R50%); (4) and maximum dose in percentage of PD at 2cm from PTV in any direction (D2cm) to follow Radiation Therapy Oncology Group (RTOG) 0915. We have retrospectively reviewed 66 separate spine lesions treated between September 2009 and December 2012 (31 treated before September 2011 [group 1] and 35 treated after [group 2]). The χ2 test was used to examine the difference in parameters between groups. The PTV V100% PD ≥ 95% objective was met in 29.0% of group 1 vs 91.4% of group 2 (p < 0.01) plans. The PTV V90% PD ≥ 99% objective was met in 38.7% of group 1 vs 88.6% of group 2 (p < 0.01) plans. Overall, 4 plans in group 1 had CI > 1.2 vs none in group 2 (p = 0.04). For D2cm, 48.3% plans yielded a minor violation of the objectives and 16.1% a major violation for group 1, whereas 17.1% exhibited a minor violation and 2.9% a major violation for group 2 (p < 0.01). Spine SBRT plans can be improved on dose coverage, conformity, and dose falloff employing a combination of RTOG spine and lung SBRT protocol planning objectives.

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