Planned versus ‘delivered’ bladder dose reconstructed using solid and hollow organ models during prostate cancer IMRT

Tara Rosewall, Janelle Wheat, Geoffrey Currie, Vickie Kong, Andrew J. Bayley, Joanne Moseley, Peter Chung, Charles Catton, Tim Craig, Michael Milosevic

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Abstract

Background and purpose All studies to date have evaluated the dosimetric effect of bladder deformation using an organ model that includes the dose to the urine. This research reconstructed bladder dose using both hollow and solid organ models, to determine if dose/volume differences exist. Materials and methods 35 prostate IMRT patients were selected, who had received 78 Gy in 39 fractions and full bladder instructions. Biomechanical modelling and finite element analysis were used to reconstruct bladder dose (solid and hollow organ model) using every third CBCT throughout the treatment course. Results Reconstructed dose (ReconDose) was 11.3 Gy greater than planned dose (planDose) with a hollow bladder model (p < 0.001) and 12.3 Gy greater with a solid bladder model (p < 0.0001). Median reconstructed volumes within the 30 Gy, 65 Gy and 78 Gy isodoses were 3–4 times larger with the solid organ model (p < 0.0001). The difference between planning bladder volume and median treatment volume was associated with the difference between the planDose and reconDose below 78 Gy (R2 > 0.61). Conclusions Substantial differences exist between planned and reconstructed bladder dose, associated with the differences in bladder filling between planning and treatment. Dose reconstructed using a solid bladder model over-reports the volume of bladder within key isodose levels and overestimates the differences between planned and reconstructed dose. Dose reconstruction with a hollow organ model is recommended if the goal is to associate that dose with toxicity.

Original languageEnglish
Pages (from-to)417-422
Number of pages6
JournalRadiotherapy and Oncology
Volume119
Issue number3
DOIs
Publication statusPublished - 01 Jun 2016

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Prostatic Neoplasms
Urinary Bladder
Finite Element Analysis
Prostate
Urine
Therapeutics
Research

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Rosewall, Tara ; Wheat, Janelle ; Currie, Geoffrey ; Kong, Vickie ; Bayley, Andrew J. ; Moseley, Joanne ; Chung, Peter ; Catton, Charles ; Craig, Tim ; Milosevic, Michael. / Planned versus ‘delivered’ bladder dose reconstructed using solid and hollow organ models during prostate cancer IMRT. In: Radiotherapy and Oncology. 2016 ; Vol. 119, No. 3. pp. 417-422.
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abstract = "Background and purpose All studies to date have evaluated the dosimetric effect of bladder deformation using an organ model that includes the dose to the urine. This research reconstructed bladder dose using both hollow and solid organ models, to determine if dose/volume differences exist. Materials and methods 35 prostate IMRT patients were selected, who had received 78 Gy in 39 fractions and full bladder instructions. Biomechanical modelling and finite element analysis were used to reconstruct bladder dose (solid and hollow organ model) using every third CBCT throughout the treatment course. Results Reconstructed dose (ReconDose) was 11.3 Gy greater than planned dose (planDose) with a hollow bladder model (p < 0.001) and 12.3 Gy greater with a solid bladder model (p < 0.0001). Median reconstructed volumes within the 30 Gy, 65 Gy and 78 Gy isodoses were 3–4 times larger with the solid organ model (p < 0.0001). The difference between planning bladder volume and median treatment volume was associated with the difference between the planDose and reconDose below 78 Gy (R2 > 0.61). Conclusions Substantial differences exist between planned and reconstructed bladder dose, associated with the differences in bladder filling between planning and treatment. Dose reconstructed using a solid bladder model over-reports the volume of bladder within key isodose levels and overestimates the differences between planned and reconstructed dose. Dose reconstruction with a hollow organ model is recommended if the goal is to associate that dose with toxicity.",
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Planned versus ‘delivered’ bladder dose reconstructed using solid and hollow organ models during prostate cancer IMRT. / Rosewall, Tara; Wheat, Janelle; Currie, Geoffrey; Kong, Vickie; Bayley, Andrew J.; Moseley, Joanne; Chung, Peter; Catton, Charles; Craig, Tim; Milosevic, Michael.

In: Radiotherapy and Oncology, Vol. 119, No. 3, 01.06.2016, p. 417-422.

Research output: Contribution to journalArticle

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T1 - Planned versus ‘delivered’ bladder dose reconstructed using solid and hollow organ models during prostate cancer IMRT

AU - Rosewall, Tara

AU - Wheat, Janelle

AU - Currie, Geoffrey

AU - Kong, Vickie

AU - Bayley, Andrew J.

AU - Moseley, Joanne

AU - Chung, Peter

AU - Catton, Charles

AU - Craig, Tim

AU - Milosevic, Michael

PY - 2016/6/1

Y1 - 2016/6/1

N2 - Background and purpose All studies to date have evaluated the dosimetric effect of bladder deformation using an organ model that includes the dose to the urine. This research reconstructed bladder dose using both hollow and solid organ models, to determine if dose/volume differences exist. Materials and methods 35 prostate IMRT patients were selected, who had received 78 Gy in 39 fractions and full bladder instructions. Biomechanical modelling and finite element analysis were used to reconstruct bladder dose (solid and hollow organ model) using every third CBCT throughout the treatment course. Results Reconstructed dose (ReconDose) was 11.3 Gy greater than planned dose (planDose) with a hollow bladder model (p < 0.001) and 12.3 Gy greater with a solid bladder model (p < 0.0001). Median reconstructed volumes within the 30 Gy, 65 Gy and 78 Gy isodoses were 3–4 times larger with the solid organ model (p < 0.0001). The difference between planning bladder volume and median treatment volume was associated with the difference between the planDose and reconDose below 78 Gy (R2 > 0.61). Conclusions Substantial differences exist between planned and reconstructed bladder dose, associated with the differences in bladder filling between planning and treatment. Dose reconstructed using a solid bladder model over-reports the volume of bladder within key isodose levels and overestimates the differences between planned and reconstructed dose. Dose reconstruction with a hollow organ model is recommended if the goal is to associate that dose with toxicity.

AB - Background and purpose All studies to date have evaluated the dosimetric effect of bladder deformation using an organ model that includes the dose to the urine. This research reconstructed bladder dose using both hollow and solid organ models, to determine if dose/volume differences exist. Materials and methods 35 prostate IMRT patients were selected, who had received 78 Gy in 39 fractions and full bladder instructions. Biomechanical modelling and finite element analysis were used to reconstruct bladder dose (solid and hollow organ model) using every third CBCT throughout the treatment course. Results Reconstructed dose (ReconDose) was 11.3 Gy greater than planned dose (planDose) with a hollow bladder model (p < 0.001) and 12.3 Gy greater with a solid bladder model (p < 0.0001). Median reconstructed volumes within the 30 Gy, 65 Gy and 78 Gy isodoses were 3–4 times larger with the solid organ model (p < 0.0001). The difference between planning bladder volume and median treatment volume was associated with the difference between the planDose and reconDose below 78 Gy (R2 > 0.61). Conclusions Substantial differences exist between planned and reconstructed bladder dose, associated with the differences in bladder filling between planning and treatment. Dose reconstructed using a solid bladder model over-reports the volume of bladder within key isodose levels and overestimates the differences between planned and reconstructed dose. Dose reconstruction with a hollow organ model is recommended if the goal is to associate that dose with toxicity.

KW - Bladder wall

KW - Deformable registration

KW - Dose accumulation

KW - Intensity Modulated Radiation Therapy

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