Changes in prostate orientation due to removal of a Foley catheter

Litzenberg, Dale W.; Muenz, Daniel; Archer, Paul; Jackson, Will; Hamstra, Daniel A.; Hearn, Jason W.D.; Schipper, Matthew J.; Spratt, Daniel E.

doi:10.1002/mp.12830

Cited by 15 publications

(12 citation statements)

References 33 publications

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“…Other studies investigating the impact of prostate rotations have tended to focus on the dosimetric changes to the PTV and when we look at this data it does appear that these rotations have an effect on the dose coverage of the prostate [27][28][29] , with rotations in the pitch axis generally being the primary component. 30 However, the CTV-PTV margin is meant to take motions such as these, as well as other factors including delineation error, into account in order to ensure adequate coverage of the CTV. For delineation, the use of a single observer for all contouring with a known variation of approximately 1-2mm on MRI will reduce the impact of this error, and the control for real time translational error should also reduce uncertainty.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Wolf

Nicholls

Hunter

et al. 2019

Radiotherapy and Oncology

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Background & Purpose Accurate delivery of radiotherapy is critical to achieve optimal treatment outcomes. Interfraction translational IGRT is now standard, and intrafraction motion management is becoming accessible. Some platforms can report both translational and rotational movements in real time. This study aims to quantify the dosimetric impact of observed intrafraction rotation of the prostate measured using monitoring software. Materials & Methods A dose grid resampling algorithm was used to model the dosimetric impact of prostate rotations for 20 patients on a SBRT prostate clinical trial. Translations were corrected before and during treatment, but rotations were not. Real time rotation data was acquired using KIM and a cumulative histogram analysis performed. Prostate volumes were rotated by the range of observed angles and used to calculate DVH data. Results The pitch axis had a higher range of observed rotations resulting in only 7 patients spending at least 90% of the beam on time across all fractions within rotation angles resulting in PTV D95%≥36Gy in this axis. The yaw and roll axes saw 17 and 15 patients respectively achieving this criterion. All but one of 20 patients exceeded CTV D98% ≥36Gy for all observed rotation angles. Conclusions Current CTV-PTV margins do not result in compromised CTV dose coverage due to inter and intrafraction prostate rotations in the absence of other uncertainties. Reduced PTV dosing is due to the extremely conformal treatment delivery but is unlikely to be clinically deleterious. Prostate standard IGRT should continue to focus on correcting any observed translational movements. Margin reduction could be explored in conjunction with other uncertainties. Highlights • Prostate intrafraction rotations are typically non-symmetrical about the pitch axis • Observed rotations resulted in reduced PTV dose coverage for many patients • CTV coverage was maintained for virtually all observed rotations • Existing SBRT CTV-PTV margins sufficient to account for intrafraction rotations

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Section: Discussionmentioning

confidence: 99%

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Wolf

Nicholls

Hunter

et al. 2019

Radiotherapy and Oncology

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“…In addition, the results may have suggested that the Foley catheter in the urethra itself has changed the actual position of the urethra at rest. A recent study by Litzenberg et al showed that removing the Foley catheter from the urethra caused significant prostate rotation [12].…”

Section: Discussionmentioning

confidence: 99%

“…Recently, urethra-sparing radiotherapy (USRT) using IG-IMRT, in which the dose to the prostatic urethra (Fig. 1) is intentionally reduced, is attracting attention and reported as an attempt to minimize GU toxicities furthermore [9–12]. For example, Shimizu et al have proposed USRT for prostate cancer [10] using fluoroscopic real-time tracking technology, called real-time tumor-tracking radiotherapy, and three fiducial gold markers with the accuracy of ±1–2 mm [13–18].…”

Section: Introductionmentioning

confidence: 99%

“…The position of the Foley catheter in the prostate gland has also been used as the basis of the urethral position in CT planning [21, 22]. However, there is also a concern that the Foley catheter may rotate or shift the physiological position of the urethra from the actual position of the “urethra without the catheter” [12, 21]. As a result, if a Foley catheter is used in CT for treatment planning but not in the actual delivery of USRT, there is a risk of introducing discrepancies in the urethral position and dose distribution between the planned treatment and the actual treatment.…”

Section: Introductionmentioning

confidence: 99%

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The urethral position may shift due to urethral catheter placement in the treatment planning for prostate radiation therapy

et al. 2019

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PurposeTo determine the best method to contour the planning organ at risk volume (PRV) for the urethra, this study aimed to investigate the displacement of a Foley catheter in the urethra with a soft and thin guide-wire.MethodsFor each patient, the study used two sets of computed tomography (CT) images for radiation treatment planning (RT-CT): (1) set with a Foley urethral catheter (4.0 mm diameter) plus a guide-wire (0.46 mm diameter) in the first RT-CT and (2) set with a guide-wire alone in the second CT recorded 2 min after the first RT-CT. Using three fiducial markers in the prostate for image fusion, the displacement between the catheter and the guide-wire in the prostatic urethra was calculated. In 155 consecutive patients treated between 2011 and 2017, 5531 slices of RT-CT were evaluated.ResultsAssuming that ≥3.0 mm of difference between the catheter and the guide-wire position was a significant displacement, the urethra with the catheter was displaced significantly from the urethra with the guide-wire alone in > 20% of the RT-CT slices in 23.2% (36/155) of the patients. The number of patients who showed ≥3.0 mm anterior displacement with the catheter in ≥20% RT-CT slices was significantly larger at the superior segment (38/155) than at the middle (14/155) and inferior segments (18/155) of the prostatic urethra (p < 0.0167).ConclusionsThe urethral position with a Foley catheter is different from the urethral position with a thin and soft guide-wire in a significant proportion of the patients. This should be taken into account for the PRV of the urethra to ensure precise radiotherapy such as in urethra-sparing radiotherapy.

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“…However, this method must be done prior to each treatment, is invasive and can lead to infection. Additionally, the catheter can also rotate and deform the urethra, resulting in potential organ misalignment during each treatment delivery [ 8 , 9 , 10 ]. As a result, some physicians choose to contour the prostatic urethra on the planning CT based on prior experience and knowledge.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of T2-Weighted MRI for Visualization and Sparing of Urethra with MR-Guided Radiation Therapy (MRgRT) On-Board MRI

Pham

Savjani

Gao

et al. 2021

Cancers

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Purpose: To evaluate urethral contours from two optimized urethral MRI sequences with an MR-guided radiotherapy system (MRgRT). Methods: Eleven prostate cancer patients were scanned on a MRgRT system using optimized urethral 3D HASTE and 3D TSE. A resident radiation oncologist contoured the prostatic urethra on the patients’ planning CT, diagnostic 3T T2w MRI, and both urethral MRIs. An attending radiation oncologist reviewed/edited the resident’s contours and additionally contoured the prostatic urethra on the clinical planning MRgRT MRI (bSSFP). For each image, the resident radiation oncologist, attending radiation oncologist, and a senior medical physicist qualitatively scored the prostatic urethra visibility. Using MRgRT 3D HASTE-based contouring workflow as baseline, prostatic urethra contours drawn on CT, diagnostic MRI, clinical bSSFP and 3D TSE were evaluated relative to the contour on 3D HASTE using 95th percentile Hausdorff distance (HD95), mean-distance-to-agreement (MDA), and DICE coefficient. Additionally, prostatic urethra contrast-to-noise-ratios (CNR) were calculated for all images. Results: For two out of three observers, the urethra visibility score for 3D HASTE was significantly higher than CT, and clinical bSSFP, but was not significantly different from diagnostic MRI. The mean HD95/MDA/DICE values were 11.35 ± 3.55 mm/5.77 ± 2.69 mm/0.07 ± 0.08 for CT, 7.62 ± 2.75 mm/3.83 ± 1.47 mm/0.12 ± 0.10 for CT + diagnostic MRI, 5.49 ± 2.32 mm/2.18 ± 1.19 mm/0.35 ± 0.19 for 3D TSE, and 6.34 ± 2.89 mm/2.65 ± 1.31 mm/0.21 ± 0.12 for clinical bSSFP. The CNR for 3D HASTE was significantly higher than CT, diagnostic MRI, and clinical bSSFP, but was not significantly different from 3D TSE. Conclusion: The urethra’s visibility scores showed optimized urethral MRgRT 3D HASTE was superior to the other tested methodologies. The prostatic urethra contours demonstrated significant variability from different imaging and workflows. Urethra contouring uncertainty introduced by cross-modality registration and sub-optimal imaging contrast may lead to significant treatment degradation when urethral sparing is implemented to minimize genitourinary toxicity.

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Changes in prostate orientation due to removal of a Foley catheter

Cited by 15 publications

References 33 publications

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

The urethral position may shift due to urethral catheter placement in the treatment planning for prostate radiation therapy

Evaluation of T2-Weighted MRI for Visualization and Sparing of Urethra with MR-Guided Radiation Therapy (MRgRT) On-Board MRI

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