Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer

Ditte Sloth Møller; Marianne Marquard Knap; Tine Bisballe Nyeng; Azza Ahmed Khalil; Marianne Ingerslev Holt; Maria Kandi; Lone Hoffmann

doi:10.1080/0284186X.2017.1373848

Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer

Ditte Sloth Møller, Marianne Marquard Knap, Tine Bisballe Nyeng, Azza Ahmed Khalil, Marianne Ingerslev Holt, Maria Kandi, Lone Hoffmann

Department of Clinical Medicine - The Department of Oncology

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

12 Citations (Scopus)

Abstract

Introduction: Minimizing the planning target volume (PTV) while ensuring sufficient target coverage during the entire respiratory cycle is essential for free-breathing radiotherapy of lung cancer. Different methods are used to incorporate the respiratory motion into the PTV. Material and methods: Fifteen patients were analyzed. Respiration can be included in the target delineation process creating a respiratory GTV, denoted iGTV. Alternatively, the respiratory amplitude (A) can be measured based on the 4D-CT and A can be incorporated in the margin expansion. The GTV expanded by A yielded GTV + resp, which was compared to iGTV in terms of overlap. Three methods for PTV generation were compared. PTV _del (delineated iGTV expanded to CTV plus PTV margin), PTV _σ (GTV expanded to CTV and A was included as a random uncertainty in the CTV to PTV margin) and PTV _∑ (GTV expanded to CTV, succeeded by CTV linear expansion by A to CTV + resp, which was finally expanded to PTV _∑). Results: Deformation of tumor and lymph nodes during respiration resulted in volume changes between the respiratory phases. The overlap between iGTV and GTV + resp showed that on average 7% of iGTV was outside the GTV + resp implying that GTV + resp did not capture the tumor during the full deformable respiration cycle. A comparison of the PTV volumes showed that PTV _σ was smallest and PTV _Σ largest for all patients. PTV _σ was in mean 14% (31 cm ³) smaller than PTV _del, while PTV _del was 7% (20 cm ³) smaller than PTV _Σ. Conclusions: PTV _σ yields the smallest volumes but does not ensure coverage of tumor during the full respiratory motion due to tumor deformation. Incorporating the respiratory motion in the delineation (PTV _del) takes into account the entire respiratory cycle including deformation, but at the cost, however, of larger treatment volumes. PTV _Σ should not be used, since it incorporates the disadvantages of both PTV _del and PTV _σ.

Original language	English
Journal	Acta Oncologica
Volume	56
Issue	11
Pages (from-to)	1604-1609
Number of pages	6
ISSN	0284-186X
DOIs	https://doi.org/10.1080/0284186X.2017.1373848
Publication status	Published - 2 Nov 2017

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@article{e23194a4db3541e2894b4148b61f447e,

title = "Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer",

abstract = "Introduction: Minimizing the planning target volume (PTV) while ensuring sufficient target coverage during the entire respiratory cycle is essential for free-breathing radiotherapy of lung cancer. Different methods are used to incorporate the respiratory motion into the PTV. Material and methods: Fifteen patients were analyzed. Respiration can be included in the target delineation process creating a respiratory GTV, denoted iGTV. Alternatively, the respiratory amplitude (A) can be measured based on the 4D-CT and A can be incorporated in the margin expansion. The GTV expanded by A yielded GTV + resp, which was compared to iGTV in terms of overlap. Three methods for PTV generation were compared. PTV del (delineated iGTV expanded to CTV plus PTV margin), PTV σ (GTV expanded to CTV and A was included as a random uncertainty in the CTV to PTV margin) and PTV ∑ (GTV expanded to CTV, succeeded by CTV linear expansion by A to CTV + resp, which was finally expanded to PTV ∑). Results: Deformation of tumor and lymph nodes during respiration resulted in volume changes between the respiratory phases. The overlap between iGTV and GTV + resp showed that on average 7% of iGTV was outside the GTV + resp implying that GTV + resp did not capture the tumor during the full deformable respiration cycle. A comparison of the PTV volumes showed that PTV σ was smallest and PTV Σ largest for all patients. PTV σ was in mean 14% (31 cm 3) smaller than PTV del, while PTV del was 7% (20 cm 3) smaller than PTV Σ. Conclusions: PTV σ yields the smallest volumes but does not ensure coverage of tumor during the full respiratory motion due to tumor deformation. Incorporating the respiratory motion in the delineation (PTV del) takes into account the entire respiratory cycle including deformation, but at the cost, however, of larger treatment volumes. PTV Σ should not be used, since it incorporates the disadvantages of both PTV del and PTV σ.",

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author = "{Sloth M{\o}ller}, Ditte and Knap, {Marianne Marquard} and Nyeng, {Tine Bisballe} and Khalil, {Azza Ahmed} and Holt, {Marianne Ingerslev} and Maria Kandi and Lone Hoffmann",

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doi = "10.1080/0284186X.2017.1373848",

language = "English",

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Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer. / Sloth Møller, Ditte; Knap, Marianne Marquard; Nyeng, Tine Bisballe et al.
In: Acta Oncologica, Vol. 56, No. 11, 02.11.2017, p. 1604-1609.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer

AU - Sloth Møller, Ditte

AU - Knap, Marianne Marquard

AU - Nyeng, Tine Bisballe

AU - Khalil, Azza Ahmed

AU - Holt, Marianne Ingerslev

AU - Kandi, Maria

AU - Hoffmann, Lone

PY - 2017/11/2

Y1 - 2017/11/2

N2 - Introduction: Minimizing the planning target volume (PTV) while ensuring sufficient target coverage during the entire respiratory cycle is essential for free-breathing radiotherapy of lung cancer. Different methods are used to incorporate the respiratory motion into the PTV. Material and methods: Fifteen patients were analyzed. Respiration can be included in the target delineation process creating a respiratory GTV, denoted iGTV. Alternatively, the respiratory amplitude (A) can be measured based on the 4D-CT and A can be incorporated in the margin expansion. The GTV expanded by A yielded GTV + resp, which was compared to iGTV in terms of overlap. Three methods for PTV generation were compared. PTV del (delineated iGTV expanded to CTV plus PTV margin), PTV σ (GTV expanded to CTV and A was included as a random uncertainty in the CTV to PTV margin) and PTV ∑ (GTV expanded to CTV, succeeded by CTV linear expansion by A to CTV + resp, which was finally expanded to PTV ∑). Results: Deformation of tumor and lymph nodes during respiration resulted in volume changes between the respiratory phases. The overlap between iGTV and GTV + resp showed that on average 7% of iGTV was outside the GTV + resp implying that GTV + resp did not capture the tumor during the full deformable respiration cycle. A comparison of the PTV volumes showed that PTV σ was smallest and PTV Σ largest for all patients. PTV σ was in mean 14% (31 cm 3) smaller than PTV del, while PTV del was 7% (20 cm 3) smaller than PTV Σ. Conclusions: PTV σ yields the smallest volumes but does not ensure coverage of tumor during the full respiratory motion due to tumor deformation. Incorporating the respiratory motion in the delineation (PTV del) takes into account the entire respiratory cycle including deformation, but at the cost, however, of larger treatment volumes. PTV Σ should not be used, since it incorporates the disadvantages of both PTV del and PTV σ.

AB - Introduction: Minimizing the planning target volume (PTV) while ensuring sufficient target coverage during the entire respiratory cycle is essential for free-breathing radiotherapy of lung cancer. Different methods are used to incorporate the respiratory motion into the PTV. Material and methods: Fifteen patients were analyzed. Respiration can be included in the target delineation process creating a respiratory GTV, denoted iGTV. Alternatively, the respiratory amplitude (A) can be measured based on the 4D-CT and A can be incorporated in the margin expansion. The GTV expanded by A yielded GTV + resp, which was compared to iGTV in terms of overlap. Three methods for PTV generation were compared. PTV del (delineated iGTV expanded to CTV plus PTV margin), PTV σ (GTV expanded to CTV and A was included as a random uncertainty in the CTV to PTV margin) and PTV ∑ (GTV expanded to CTV, succeeded by CTV linear expansion by A to CTV + resp, which was finally expanded to PTV ∑). Results: Deformation of tumor and lymph nodes during respiration resulted in volume changes between the respiratory phases. The overlap between iGTV and GTV + resp showed that on average 7% of iGTV was outside the GTV + resp implying that GTV + resp did not capture the tumor during the full deformable respiration cycle. A comparison of the PTV volumes showed that PTV σ was smallest and PTV Σ largest for all patients. PTV σ was in mean 14% (31 cm 3) smaller than PTV del, while PTV del was 7% (20 cm 3) smaller than PTV Σ. Conclusions: PTV σ yields the smallest volumes but does not ensure coverage of tumor during the full respiratory motion due to tumor deformation. Incorporating the respiratory motion in the delineation (PTV del) takes into account the entire respiratory cycle including deformation, but at the cost, however, of larger treatment volumes. PTV Σ should not be used, since it incorporates the disadvantages of both PTV del and PTV σ.

KW - Journal Article

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JO - Acta Oncologica

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Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer

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