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Original article
peer-reviewed

Targeting the Tumor: Assessing the Impact of Bladder Volume and Position on Accuracy of Radiation Delivery for Patients with Bladder Cancer



Abstract

Context

Daily variations in bladder size and position can negatively impact the ability to accurately deliver radiation.

Aims

We attempted to quantify how bladder volumes and positions change over the course of radiotherapy for muscle invasive bladder cancer and the planning target volume (PTV) margins required to account for such changes.

Methods and material

Cone-beam computed tomography (CT) images of 28 patients during their first, second, and third fractions and weekly thereafter were acquired. Bladders were contoured and the volume, centre of mass, and the maximal positions were recorded and compared to the planning CT scan.

Statistical analysis

Bladder parameters were analysed using regression analysis examining for time trends and correlation to the patient, tumour, or treatment-related factors.

Results

There was great variability in the mean bladder volumes during the radiotherapy courses (154.17 +/- 129.38 cm3). There were no statistically significant trends for volume changes. Deviations in bladder positions were seen but were small in magnitude. No patient factors were identified which could help predict bladder changes clinically. Bladder variability resulted in a high percentage of fractions (39.6%) in which part of the bladder was outside the PTV. Calculated PTV margins (for 90% of the population to receive 95% of the prescription dose) were 1.48 cm right, 1.15 cm left, 2.13 cm posterior, 1.52 cm anterior, 2.23 cm superior, and 0.52 cm inferior.

Conclusions

Because of random bladder changes, a significant number of fractions were treated in which the clinical target volume (CTV) fell outside of the PTV. Methods to minimize the amount of CTV that is missed on a fraction to fraction basis should be explored.



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Original article
peer-reviewed

Targeting the Tumor: Assessing the Impact of Bladder Volume and Position on Accuracy of Radiation Delivery for Patients with Bladder Cancer


Author Information

Andrew Kochan Corresponding Author

Faculty of Medicine, University of Manitoba

Ryan Rivest

Radiation Oncology, Cancercare Manitoba

Katie Galloway

Epidemiology and Cancer Registry, Cancercare Manitoba

Pascal Lambert

Epidemiology and Cancer Registry, Cancercare Manitoba

Aldrich Ong

Radiation Oncology, Cancercare Manitoba

Rashmi Koul

Radiation Oncology, CancerCare Manitoba, University of Manitoba

Shahida Ahmed

Radiation Oncology, CancerCare Manitoba, CancerCare Manitoba, University of Manitoba

Bashir Bashir

Radiation Oncology, CancerCare Manitoba, University of Manitoba

Harvey Quon

Radiation Oncology, Tom Baker Cancer Centre


Ethics Statement and Conflict of Interest Disclosures

Human subjects: Consent was obtained by all participants in this study. University of Manitoba Research Ethics Board issued approval H2015:173 (HS 18588). Animal subjects: This study did not involve animal subjects or tissue. Conflicts of interest: The authors have declared that no conflicts of interest exist.


Original article
peer-reviewed

Targeting the Tumor: Assessing the Impact of Bladder Volume and Position on Accuracy of Radiation Delivery for Patients with Bladder Cancer


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Original article
peer-reviewed

Targeting the Tumor: Assessing the Impact of Bladder Volume and Position on Accuracy of Radiation Delivery for Patients with Bladder Cancer

  • Author Information
    Andrew Kochan Corresponding Author

    Faculty of Medicine, University of Manitoba

    Ryan Rivest

    Radiation Oncology, Cancercare Manitoba

    Katie Galloway

    Epidemiology and Cancer Registry, Cancercare Manitoba

    Pascal Lambert

    Epidemiology and Cancer Registry, Cancercare Manitoba

    Aldrich Ong

    Radiation Oncology, Cancercare Manitoba

    Rashmi Koul

    Radiation Oncology, CancerCare Manitoba, University of Manitoba

    Shahida Ahmed

    Radiation Oncology, CancerCare Manitoba, CancerCare Manitoba, University of Manitoba

    Bashir Bashir

    Radiation Oncology, CancerCare Manitoba, University of Manitoba

    Harvey Quon

    Radiation Oncology, Tom Baker Cancer Centre


    Ethics Statement and Conflict of Interest Disclosures

    Human subjects: Consent was obtained by all participants in this study. University of Manitoba Research Ethics Board issued approval H2015:173 (HS 18588). Animal subjects: This study did not involve animal subjects or tissue. Conflicts of interest: The authors have declared that no conflicts of interest exist.

    Acknowledgements


    Article Information

    Published: September 01, 2017

    DOI

    10.7759/cureus.1638

    Cite this article as:

    Kochan A, Rivest R, Galloway K, et al. (September 01, 2017) Targeting the Tumor: Assessing the Impact of Bladder Volume and Position on Accuracy of Radiation Delivery for Patients with Bladder Cancer. Cureus 9(9): e1638. doi:10.7759/cureus.1638

    Publication history

    Received by Cureus: April 04, 2017
    Peer review began: April 12, 2017
    Peer review concluded: August 23, 2017
    Published: September 01, 2017

    Copyright

    © Copyright 2017
    Kochan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 3.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    License

    This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Context

Daily variations in bladder size and position can negatively impact the ability to accurately deliver radiation.

Aims

We attempted to quantify how bladder volumes and positions change over the course of radiotherapy for muscle invasive bladder cancer and the planning target volume (PTV) margins required to account for such changes.

Methods and material

Cone-beam computed tomography (CT) images of 28 patients during their first, second, and third fractions and weekly thereafter were acquired. Bladders were contoured and the volume, centre of mass, and the maximal positions were recorded and compared to the planning CT scan.

Statistical analysis

Bladder parameters were analysed using regression analysis examining for time trends and correlation to the patient, tumour, or treatment-related factors.

Results

There was great variability in the mean bladder volumes during the radiotherapy courses (154.17 +/- 129.38 cm3). There were no statistically significant trends for volume changes. Deviations in bladder positions were seen but were small in magnitude. No patient factors were identified which could help predict bladder changes clinically. Bladder variability resulted in a high percentage of fractions (39.6%) in which part of the bladder was outside the PTV. Calculated PTV margins (for 90% of the population to receive 95% of the prescription dose) were 1.48 cm right, 1.15 cm left, 2.13 cm posterior, 1.52 cm anterior, 2.23 cm superior, and 0.52 cm inferior.

Conclusions

Because of random bladder changes, a significant number of fractions were treated in which the clinical target volume (CTV) fell outside of the PTV. Methods to minimize the amount of CTV that is missed on a fraction to fraction basis should be explored.



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Create a free account to continue reading this article.

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Andrew Kochan

Faculty of Medicine, University of Manitoba

For correspondence:
akochan@shaw.ca

Ryan Rivest

Radiation Oncology, Cancercare Manitoba

Katie Galloway

Epidemiology and Cancer Registry, Cancercare Manitoba

Pascal Lambert

Epidemiology and Cancer Registry, Cancercare Manitoba

Aldrich Ong

Radiation Oncology, Cancercare Manitoba

Rashmi Koul

Radiation Oncology, CancerCare Manitoba, University of Manitoba

Shahida Ahmed

Radiation Oncology, CancerCare Manitoba, CancerCare Manitoba, University of Manitoba

Bashir Bashir

Radiation Oncology, CancerCare Manitoba, University of Manitoba

Harvey Quon

Radiation Oncology, Tom Baker Cancer Centre

Andrew Kochan

Faculty of Medicine, University of Manitoba

For correspondence:
akochan@shaw.ca

Ryan Rivest

Radiation Oncology, Cancercare Manitoba

Katie Galloway

Epidemiology and Cancer Registry, Cancercare Manitoba

Pascal Lambert

Epidemiology and Cancer Registry, Cancercare Manitoba

Aldrich Ong

Radiation Oncology, Cancercare Manitoba

Rashmi Koul

Radiation Oncology, CancerCare Manitoba, University of Manitoba

Shahida Ahmed

Radiation Oncology, CancerCare Manitoba, CancerCare Manitoba, University of Manitoba

Bashir Bashir

Radiation Oncology, CancerCare Manitoba, University of Manitoba

Harvey Quon

Radiation Oncology, Tom Baker Cancer Centre