Limits...
Effect of a urinary catheter on seed position and rectal and bladder doses in CT-based post-implant dosimetry for prostate cancer brachytherapy.

Kunogi H, Yamaguchi N, Wakumoto Y, Sasai K - J Contemp Brachytherapy (2015)

Bottom Line: We compared the rectal and bladder doses in 18 patients on each CT series.Radiation doses to the bladder with a catheter were significantly lower than those without a catheter (p = 0.027).Post-implant dosimetry (PID) with no catheter showed significantly lower rectal doses and higher bladder doses than those of PID with a catheter.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology.

ABSTRACT

Purpose: To assess the variability in rectal and bladder dosimetric parameters determined according to post-implant computed tomography (CT) images in patients with or without a urethral catheter.

Material and methods: Patients with prostate cancer who were scheduled to undergo CT after brachytherapy between October 2012 and January 2014 were included. We obtained CT series with and without a urinary catheter in each patient. We compared the rectal and bladder doses in 18 patients on each CT series.

Results: The shifts in the seed positions between with and without a catheter in place were 1.3 ± 0.3 mm (mean ± standard deviation). The radiation doses to the rectum, as determined on the CT series, with a urethral catheter were higher than those on CT without a catheter (p < 0.001). Radiation doses to the bladder with a catheter were significantly lower than those without a catheter (p = 0.027).

Conclusions: Post-implant dosimetry (PID) with no catheter showed significantly lower rectal doses and higher bladder doses than those of PID with a catheter. We recommend the PID procedure for CT images in patients without a catheter. Use of CT with a catheter is limited to identifying urethral position.

No MeSH data available.


Related in: MedlinePlus

Example of isodose distributions in the sagittal plane (left) and transverse plane (right) on each PID. In the two upper images, the prostate (red), urethra (green), bladder (yellow), and rectum (dark blue) are contoured on CT images with a catheter. On the two lower images, the prostate (blue), urethra (lemon), bladder (light green), and rectum (light yellow) are contoured on CT images without a catheter. Each red source image indicates each seed source position (the bright image) on each CT image. The seeds move with the target, and a shift in the dose distribution is apparent. The overlay of the 100% isodose area and rectum volume on PID without a catheter is less than that on PID with a catheter
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4499521&req=5

Figure 0001: Example of isodose distributions in the sagittal plane (left) and transverse plane (right) on each PID. In the two upper images, the prostate (red), urethra (green), bladder (yellow), and rectum (dark blue) are contoured on CT images with a catheter. On the two lower images, the prostate (blue), urethra (lemon), bladder (light green), and rectum (light yellow) are contoured on CT images without a catheter. Each red source image indicates each seed source position (the bright image) on each CT image. The seeds move with the target, and a shift in the dose distribution is apparent. The overlay of the 100% isodose area and rectum volume on PID without a catheter is less than that on PID with a catheter

Mentions: The prostate was contoured with and without a urinary catheter. The D90 (i.e., minimum dose received by 90% of the prostate volume expressed as a percentage of the prescription dose) and V100 values (i.e., percentage of the prostate volume covered by 100% of the prescription dose) were estimated to verify the validity of the prostate dose coverage in this study. The prostatic urethra was contoured with and without a urinary catheter. The urethra on PID with the catheter was contoured as a circular structure 4 mm in diameter based on a urinary catheter position from the prostatic base to the apex (Figure 1), and the urethra on PID without the catheter was contoured as a circular structure of the same diameter (4 mm) by adequately adjusting the position of the urethra on fusing CT images with the catheter considering the shift of the seeds located close to the catheter.


Effect of a urinary catheter on seed position and rectal and bladder doses in CT-based post-implant dosimetry for prostate cancer brachytherapy.

Kunogi H, Yamaguchi N, Wakumoto Y, Sasai K - J Contemp Brachytherapy (2015)

Example of isodose distributions in the sagittal plane (left) and transverse plane (right) on each PID. In the two upper images, the prostate (red), urethra (green), bladder (yellow), and rectum (dark blue) are contoured on CT images with a catheter. On the two lower images, the prostate (blue), urethra (lemon), bladder (light green), and rectum (light yellow) are contoured on CT images without a catheter. Each red source image indicates each seed source position (the bright image) on each CT image. The seeds move with the target, and a shift in the dose distribution is apparent. The overlay of the 100% isodose area and rectum volume on PID without a catheter is less than that on PID with a catheter
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4499521&req=5

Figure 0001: Example of isodose distributions in the sagittal plane (left) and transverse plane (right) on each PID. In the two upper images, the prostate (red), urethra (green), bladder (yellow), and rectum (dark blue) are contoured on CT images with a catheter. On the two lower images, the prostate (blue), urethra (lemon), bladder (light green), and rectum (light yellow) are contoured on CT images without a catheter. Each red source image indicates each seed source position (the bright image) on each CT image. The seeds move with the target, and a shift in the dose distribution is apparent. The overlay of the 100% isodose area and rectum volume on PID without a catheter is less than that on PID with a catheter
Mentions: The prostate was contoured with and without a urinary catheter. The D90 (i.e., minimum dose received by 90% of the prostate volume expressed as a percentage of the prescription dose) and V100 values (i.e., percentage of the prostate volume covered by 100% of the prescription dose) were estimated to verify the validity of the prostate dose coverage in this study. The prostatic urethra was contoured with and without a urinary catheter. The urethra on PID with the catheter was contoured as a circular structure 4 mm in diameter based on a urinary catheter position from the prostatic base to the apex (Figure 1), and the urethra on PID without the catheter was contoured as a circular structure of the same diameter (4 mm) by adequately adjusting the position of the urethra on fusing CT images with the catheter considering the shift of the seeds located close to the catheter.

Bottom Line: We compared the rectal and bladder doses in 18 patients on each CT series.Radiation doses to the bladder with a catheter were significantly lower than those without a catheter (p = 0.027).Post-implant dosimetry (PID) with no catheter showed significantly lower rectal doses and higher bladder doses than those of PID with a catheter.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology.

ABSTRACT

Purpose: To assess the variability in rectal and bladder dosimetric parameters determined according to post-implant computed tomography (CT) images in patients with or without a urethral catheter.

Material and methods: Patients with prostate cancer who were scheduled to undergo CT after brachytherapy between October 2012 and January 2014 were included. We obtained CT series with and without a urinary catheter in each patient. We compared the rectal and bladder doses in 18 patients on each CT series.

Results: The shifts in the seed positions between with and without a catheter in place were 1.3 ± 0.3 mm (mean ± standard deviation). The radiation doses to the rectum, as determined on the CT series, with a urethral catheter were higher than those on CT without a catheter (p < 0.001). Radiation doses to the bladder with a catheter were significantly lower than those without a catheter (p = 0.027).

Conclusions: Post-implant dosimetry (PID) with no catheter showed significantly lower rectal doses and higher bladder doses than those of PID with a catheter. We recommend the PID procedure for CT images in patients without a catheter. Use of CT with a catheter is limited to identifying urethral position.

No MeSH data available.


Related in: MedlinePlus