Delineating the inner bladder surface using uniform contractions from the outer surface under variable bladder filling conditions

Tara Rosewall, Andrew Bayley, Charles Catton, Peter Chung, Geoffrey Currie, Robert Heaton, Janelle Wheat, Michael Milosevic

Research output: Contribution to journalArticle

1 Citation (Scopus)
2 Downloads (Pure)

Abstract

Objective: To evaluate the methods to delineate the inner bladder (IB) surface using a uniform contraction from the outer bladder (OB) surface, assuming the bladder wall (BW) is either of constant thickness, constant volume or variable volume. Methods: 14 prostate intensity-modulated radiotherapy patients with 2 planning CTs were identified. For both CTs, OB was delineated using model-based segmentation. IB was delineated manually. Then, using uniform contractions from OB, the position of IB was approximated using a: 2.5-mm contraction, patient-specific contraction, patient specific constant wall volume method and variable wall volume method. The structures created using those strategies were compared against the manual IB contours using geometric and dosimetric indices. Results: In the presence of variable bladder filling, use of a generic or patient-specific constant contraction resulted in a significant overestimation of IB volume (112 and 113 cm3, respectively; p,0.001) that was inversely correlated with the difference in urine volume between the scans (R2.0.86). Mean differences across 95% of IB surfaces were #2mm for methods using either constant or variable wall volume. Mean dose-volume histogram (DVH) differences were ,1cm3 across the whole BW DVH when using the method that assumed a variable wall volume. Conclusion: The variable volume BW model provided the best approximation of the IB surface position under varying filling conditions, based on geometric and dosimetric indices. Advances in knowledge: Use of the equation derived in this research provides a quick and accurate method to delineate the hollow BWon serial imaging for the purposes of dose reconstruction.
Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalBritish Journal of Radiology
Volume88
Issue number1053
DOIs
Publication statusPublished - Sep 2015

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Urinary Bladder
Intensity-Modulated Radiotherapy
Prostate
Urine

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Rosewall, Tara ; Bayley, Andrew ; Catton, Charles ; Chung, Peter ; Currie, Geoffrey ; Heaton, Robert ; Wheat, Janelle ; Milosevic, Michael. / Delineating the inner bladder surface using uniform contractions from the outer surface under variable bladder filling conditions. In: British Journal of Radiology. 2015 ; Vol. 88, No. 1053. pp. 1-9.
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abstract = "Objective: To evaluate the methods to delineate the inner bladder (IB) surface using a uniform contraction from the outer bladder (OB) surface, assuming the bladder wall (BW) is either of constant thickness, constant volume or variable volume. Methods: 14 prostate intensity-modulated radiotherapy patients with 2 planning CTs were identified. For both CTs, OB was delineated using model-based segmentation. IB was delineated manually. Then, using uniform contractions from OB, the position of IB was approximated using a: 2.5-mm contraction, patient-specific contraction, patient specific constant wall volume method and variable wall volume method. The structures created using those strategies were compared against the manual IB contours using geometric and dosimetric indices. Results: In the presence of variable bladder filling, use of a generic or patient-specific constant contraction resulted in a significant overestimation of IB volume (112 and 113 cm3, respectively; p,0.001) that was inversely correlated with the difference in urine volume between the scans (R2.0.86). Mean differences across 95{\%} of IB surfaces were #2mm for methods using either constant or variable wall volume. Mean dose-volume histogram (DVH) differences were ,1cm3 across the whole BW DVH when using the method that assumed a variable wall volume. Conclusion: The variable volume BW model provided the best approximation of the IB surface position under varying filling conditions, based on geometric and dosimetric indices. Advances in knowledge: Use of the equation derived in this research provides a quick and accurate method to delineate the hollow BWon serial imaging for the purposes of dose reconstruction.",
keywords = "Bladder capacity, Bladder contraction, Bladder filling, Bladder wall, Bladder wall thickness, Clinical article, Cone beam computed tomography, Dosimetry, EMTREE medical terms: Article, Experimental design, Histogram, Human, Inner bladder surface, Intensity modulated radiation therapy, Male, Prostate cancer, Radiation dose, Radiotherapy planning system, Urine volume, Urogenital system parameters",
author = "Tara Rosewall and Andrew Bayley and Charles Catton and Peter Chung and Geoffrey Currie and Robert Heaton and Janelle Wheat and Michael Milosevic",
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Delineating the inner bladder surface using uniform contractions from the outer surface under variable bladder filling conditions. / Rosewall, Tara; Bayley, Andrew; Catton, Charles; Chung, Peter; Currie, Geoffrey; Heaton, Robert; Wheat, Janelle; Milosevic, Michael.

In: British Journal of Radiology, Vol. 88, No. 1053, 09.2015, p. 1-9.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Delineating the inner bladder surface using uniform contractions from the outer surface under variable bladder filling conditions

AU - Rosewall, Tara

AU - Bayley, Andrew

AU - Catton, Charles

AU - Chung, Peter

AU - Currie, Geoffrey

AU - Heaton, Robert

AU - Wheat, Janelle

AU - Milosevic, Michael

N1 - Includes bibliographical references.

PY - 2015/9

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N2 - Objective: To evaluate the methods to delineate the inner bladder (IB) surface using a uniform contraction from the outer bladder (OB) surface, assuming the bladder wall (BW) is either of constant thickness, constant volume or variable volume. Methods: 14 prostate intensity-modulated radiotherapy patients with 2 planning CTs were identified. For both CTs, OB was delineated using model-based segmentation. IB was delineated manually. Then, using uniform contractions from OB, the position of IB was approximated using a: 2.5-mm contraction, patient-specific contraction, patient specific constant wall volume method and variable wall volume method. The structures created using those strategies were compared against the manual IB contours using geometric and dosimetric indices. Results: In the presence of variable bladder filling, use of a generic or patient-specific constant contraction resulted in a significant overestimation of IB volume (112 and 113 cm3, respectively; p,0.001) that was inversely correlated with the difference in urine volume between the scans (R2.0.86). Mean differences across 95% of IB surfaces were #2mm for methods using either constant or variable wall volume. Mean dose-volume histogram (DVH) differences were ,1cm3 across the whole BW DVH when using the method that assumed a variable wall volume. Conclusion: The variable volume BW model provided the best approximation of the IB surface position under varying filling conditions, based on geometric and dosimetric indices. Advances in knowledge: Use of the equation derived in this research provides a quick and accurate method to delineate the hollow BWon serial imaging for the purposes of dose reconstruction.

AB - Objective: To evaluate the methods to delineate the inner bladder (IB) surface using a uniform contraction from the outer bladder (OB) surface, assuming the bladder wall (BW) is either of constant thickness, constant volume or variable volume. Methods: 14 prostate intensity-modulated radiotherapy patients with 2 planning CTs were identified. For both CTs, OB was delineated using model-based segmentation. IB was delineated manually. Then, using uniform contractions from OB, the position of IB was approximated using a: 2.5-mm contraction, patient-specific contraction, patient specific constant wall volume method and variable wall volume method. The structures created using those strategies were compared against the manual IB contours using geometric and dosimetric indices. Results: In the presence of variable bladder filling, use of a generic or patient-specific constant contraction resulted in a significant overestimation of IB volume (112 and 113 cm3, respectively; p,0.001) that was inversely correlated with the difference in urine volume between the scans (R2.0.86). Mean differences across 95% of IB surfaces were #2mm for methods using either constant or variable wall volume. Mean dose-volume histogram (DVH) differences were ,1cm3 across the whole BW DVH when using the method that assumed a variable wall volume. Conclusion: The variable volume BW model provided the best approximation of the IB surface position under varying filling conditions, based on geometric and dosimetric indices. Advances in knowledge: Use of the equation derived in this research provides a quick and accurate method to delineate the hollow BWon serial imaging for the purposes of dose reconstruction.

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KW - Dosimetry

KW - EMTREE medical terms: Article

KW - Experimental design

KW - Histogram

KW - Human

KW - Inner bladder surface

KW - Intensity modulated radiation therapy

KW - Male

KW - Prostate cancer

KW - Radiation dose

KW - Radiotherapy planning system

KW - Urine volume

KW - Urogenital system parameters

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DO - 10.1259/bjr.20140818

M3 - Article

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JO - British Journal of Radiology

JF - British Journal of Radiology

SN - 0007-1285

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