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Strahlentherapie und Onkologie

Published in:

01-02-2019 | Original Article

Penile bulb sparing in prostate cancer radiotherapy

Dose analysis of an in-house MRI system to improve contouring

Authors: F. Böckelmann, M. Hammon, S. Lettmaier, R. Fietkau, Prof. Dr. C. Bert, F. Putz

Published in: Strahlentherapie und Onkologie | Issue 2/2019

Abstract

Objective

This study aimed to assess the reduction in dose to the penile bulb (PB) achieved by MRI-based contouring following drinking and endorectal balloon (ERB) instructions.

Patients and methods

A total of 17 prostate cancer patients were treated with intensity-modulated radiation therapy (IMRT) and interstitial brachytherapy (IBT). CT and MRI datasets were acquired back-to-back based on a 65 cm³ air-filled ERB and drinking instructions. After rigid co-registration of the imaging data, the CT-based planning target volume (PTV) used for treatment planning was retrospectively compared to an MRI-based adaptive PTV and the dose to the PB was determined in each case. The adapted PTV encompassed a caudally cropped CT-based PTV which was defined on the basis of the MRI-based prostate contour plus an additional 5 mm safety margin.

Results

In the seven-field IMRT treatment plans, the MRI-based adapted PTV achieved mean (D_mean) and maximum (D_max) doses to the PB which were significantly lower (by 7.6 Gy and 10.9 Gy, respectively; p <0.05) than those of the CT-contoured PTV. For 6 patients, the estimated PB D_max (seven-field IMRT and IBT) for the adapted PTV was <70 Gy, whereas only 1 patient fulfilled this criterium with the CT-based PTV.

Conclusion

MRI-based contouring and seven-field IMRT-based treatment planning achieved dose sparing to the PB. Whereas the comparison of MRI and CT contouring only relates to external beam radiotherapy (EBRT) sparing, considering EBRT and IBT shows the improvement in PB sparing for the total treatment.

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Title: Penile bulb sparing in prostate cancer radiotherapy
Dose analysis of an in-house MRI system to improve contouring
Authors: F. Böckelmann
M. Hammon
S. Lettmaier
R. Fietkau
Prof. Dr. C. Bert
F. Putz
Publication date: 01-02-2019
Publisher: Springer Berlin Heidelberg
Published in: Strahlentherapie und Onkologie / Issue 2/2019
Print ISSN: 0179-7158
Electronic ISSN: 1439-099X
DOI: https://doi.org/10.1007/s00066-018-1377-0

Keynote webinar | Spotlight on medication adherence

Springer Medicine

Penile bulb sparing in prostate cancer radiotherapy

Dose analysis of an in-house MRI system to improve contouring

Abstract

Objective

Patients and methods

Results

Conclusion

Keynote webinar | Spotlight on medication adherence

Springer Medicine

Abstract

Objective

Patients and methods

Results

Conclusion

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