open access

Vol 21, No 6 (2016)
Original research articles
Published online: 2016-11-01
Submitted: 2015-11-19
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Target volume definition for post prostatectomy radiotherapy: Do the consensus guidelines correctly define the inferior border of the CTV?

Mo Manji, Juanita Crook, Matt Schmid, Rasika Rajapakshe
DOI: 10.1016/j.rpor.2016.07.003
·
Rep Pract Oncol Radiother 2016;21(6):525-531.

open access

Vol 21, No 6 (2016)
Original research articles
Published online: 2016-11-01
Submitted: 2015-11-19

Abstract

Aim

We compare urethrogram delineation of the caudal aspect of the anastomosis to the recommended guidelines of post prostatectomy radiotherapy.

Background

Level one evidence has established the indications for, and importance of, adjuvant radiotherapy following radical prostatectomy. Several guidelines have recently addressed delineation of the prostate bed target volume including identification of the vesico-urethral anastomosis, taken as the first CT slice caudal to visible urine in the bladder neck. The inferior border of clinical target volume is then variably defined 5–12[[ce:hsp sp="0.25"/]]mm below this anastomosis or 15[[ce:hsp sp="0.25"/]]mm cranial to the penile bulb.

Methods and materials

Thirty-three patients who received adjuvant radiotherapy following radical prostatectomy were reviewed. All underwent planning CT with urethrogram. The authors (MM, JC) independently identified the CT slice caudal to the last slice showing urine in the bladder neck (called the CT Reference Slice), and measured the distance between this and the tip of the urethrogram cone. Five patients also had a diagnostic MRI at the time of CT planning to better visualize the anatomy.

Results

Sixty-six readings were obtained. The mean distance between the Bladder CT Reference Slice and the most cranial urethrogram contrast slice was 16.1[[ce:hsp sp="0.25"/]]mm (MM 16.4[[ce:hsp sp="0.25"/]]mm, JC 15.8[[ce:hsp sp="0.25"/]]mm), range: 6.8–34.2[[ce:hsp sp="0.25"/]]mm. The mean distance between the urethrogram tip and the ischial tuberosities was 19.9[[ce:hsp sp="0.25"/]]mm (range 12.5–29.8[[ce:hsp sp="0.25"/]]mm). The mean distance between the CT Reference Slice and the ischial tuberosities was 36.9[[ce:hsp sp="0.25"/]]mm (range 28.3–52.4[[ce:hsp sp="0.25"/]]mm).

Conclusions

Guidelines for prostate bed radiation post prostatectomy have been developed after publication of the trials proving benefit of such treatment, and are thus untested. The anastomosis is a frequent site of local relapse but is variably defined by the existing guidelines, none of which take into account anatomic patient variation and all of which are at variance with urethrogram data. We recommend the use of planning urethrogram to better delineate the vesico-urethral junction and minimize the potential for geographic misses.

Abstract

Aim

We compare urethrogram delineation of the caudal aspect of the anastomosis to the recommended guidelines of post prostatectomy radiotherapy.

Background

Level one evidence has established the indications for, and importance of, adjuvant radiotherapy following radical prostatectomy. Several guidelines have recently addressed delineation of the prostate bed target volume including identification of the vesico-urethral anastomosis, taken as the first CT slice caudal to visible urine in the bladder neck. The inferior border of clinical target volume is then variably defined 5–12[[ce:hsp sp="0.25"/]]mm below this anastomosis or 15[[ce:hsp sp="0.25"/]]mm cranial to the penile bulb.

Methods and materials

Thirty-three patients who received adjuvant radiotherapy following radical prostatectomy were reviewed. All underwent planning CT with urethrogram. The authors (MM, JC) independently identified the CT slice caudal to the last slice showing urine in the bladder neck (called the CT Reference Slice), and measured the distance between this and the tip of the urethrogram cone. Five patients also had a diagnostic MRI at the time of CT planning to better visualize the anatomy.

Results

Sixty-six readings were obtained. The mean distance between the Bladder CT Reference Slice and the most cranial urethrogram contrast slice was 16.1[[ce:hsp sp="0.25"/]]mm (MM 16.4[[ce:hsp sp="0.25"/]]mm, JC 15.8[[ce:hsp sp="0.25"/]]mm), range: 6.8–34.2[[ce:hsp sp="0.25"/]]mm. The mean distance between the urethrogram tip and the ischial tuberosities was 19.9[[ce:hsp sp="0.25"/]]mm (range 12.5–29.8[[ce:hsp sp="0.25"/]]mm). The mean distance between the CT Reference Slice and the ischial tuberosities was 36.9[[ce:hsp sp="0.25"/]]mm (range 28.3–52.4[[ce:hsp sp="0.25"/]]mm).

Conclusions

Guidelines for prostate bed radiation post prostatectomy have been developed after publication of the trials proving benefit of such treatment, and are thus untested. The anastomosis is a frequent site of local relapse but is variably defined by the existing guidelines, none of which take into account anatomic patient variation and all of which are at variance with urethrogram data. We recommend the use of planning urethrogram to better delineate the vesico-urethral junction and minimize the potential for geographic misses.

Get Citation

Keywords

Prostate cancer; Post-operative radiotherapy; Adjuvant radiotherapy; Salvage radiotherapy; Planning urethrogram

About this article
Title

Target volume definition for post prostatectomy radiotherapy: Do the consensus guidelines correctly define the inferior border of the CTV?

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 21, No 6 (2016)

Pages

525-531

Published online

2016-11-01

DOI

10.1016/j.rpor.2016.07.003

Bibliographic record

Rep Pract Oncol Radiother 2016;21(6):525-531.

Keywords

Prostate cancer
Post-operative radiotherapy
Adjuvant radiotherapy
Salvage radiotherapy
Planning urethrogram

Authors

Mo Manji
Juanita Crook
Matt Schmid
Rasika Rajapakshe

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