Optimal bladder volume at treatment planning for prostate cancer patients receiving volumetric modulated arc therapy

Anatomical changes in the male pelvis between the supine and upright positions-A feasibility study for prostate treatments in the upright position

Treating and imaging patients in the upright orientation is gaining acceptance in radiation oncology and radiology and has distinct advantages over the recumbent position. An IRB approved study to investigate the positions and orientations of the male pelvic organs between the supine and upright positions was conducted. The study comprised of scanning 15 male volunteers (aged 55-75 years) on a 0.6 T Fonar MRI scanner in the supine and upright positions with a full bladder and in the upright position with an empty bladder. The Pelvic study revealed that in the upright position the 1. Position and shape of the prostate are not impacted significantly by bladder fill. 2. Distance between the sacrum and the anterior bladder wall is significantly smaller. 3. Anterior-Posterior length and the bladder width is significantly larger. 4. Seminal vesicles are pushed down by the bladder. 5. Top of the penile bulb is further away from the apex of the prostate. These observed differences could positively impact upright prostate treatments by 1. Reducing the risk of small bowel approximating the treatment volume. 2. Prostate treatments can be done with a reduced focus on bladder fill. 3. Radiation beams for treating intermediate risk prostrate can be made smaller or a larger portion of the seminal vesicles can be treated with the same beam size than typically used for supine treatments. 4. Reducing the average dose to the penile bulb.

Multi-parametric MRI for radiotherapy simulation

Magnetic resonance imaging (MRI) has become an important imaging modality in the field of radiotherapy (RT) in the past decade, especially with the development of various novel MRI and image-guidance techniques. In this review article, we will describe recent developments and discuss the applications of multi-parametric MRI (mpMRI) in RT simulation. In this review, mpMRI refers to a general and loose definition which includes various multi-contrast MRI techniques. Specifically, we will focus on the implementation, challenges, and future directions of mpMRI techniques for RT simulation.

[Benefits and limitations of using a portable ultrasound scanner (bladderscan) in pelvic radiotherapy. Narrative review of the literature]

PURPOSE

The reproducibility of bladder filling influences the target volume position for pelvis radiotherapy. The objective of this study was to summarize the current knowledge on the use of portable echograph systems named Bladderscan (BS) in this context.

MATERIAL AND METHODS

Review of the PubMed and Google Scholar publication databases was performed between September 2020 and April 2021. Results of this research were filtered in accordance to a set of eligibility criterias and are presented in this article.

RESULTS

Keyword search yielded a total of 2407 publications, which filtered down to 10 relevant articles in accordance to the eligibility criterias. These publications described the viability of the BS measures as well as their clinical and organizational repercussions.

CONCLUSION

According to multiple studies, BS allows to measure the bladder volume before each radiotherapy session. The use of BS decreases the amount of Cone Beam Computer Tomography potentially rejected due to non-conformed bladder filling, and improve the throughput of patients.

[Usefulness of an Ultrasound System with Automatic Bladder Urine Volume Measurement Using Artificial Intelligence Technology in Radiotherapy]

PURPOSE

We aimed to investigate the usefulness of iViz air ver.4 Convex (FUJIFILM, Tokyo) as a tool to determine the bladder capacity before prostate radiotherapy by comparing it with the existing BladderScan BVI 6100 (Verathon Inc., Bothell, Washington).

METHODS

We investigated the usefulness of iViz air as a tool to determine the bladder capacity before prostate radiotherapy by comparing it with the current BladderScan.

RESULTS

The absolute value of each error rate was approximately 30.9%±27.2% and 26.4%±18.9% for the BladderScan and iViz air, respectively, with no significant differences between the instruments (p=0.16). Evaluated by urine volume, the mean error rates for bladder volumes >50 ml were 26.9%±19.0% and 26.1%±18.5% for the Bladder Scan and iViz air, respectively, with no significant differences (p=0.56). However, the BladderScan and iViz air had significantly higher error rates of 89.5%±52.5% and 31.5%±25.1%, respectively, if the bladder volume was <50 ml (p=0.005).

CONCLUSION

The iViz air has limited measurement error to confirm images, especially in limited volumes, suggesting that it is a useful bladder capacity measurement device in performing prostate radiotherapy.

Bladder filling in patients undergoing prostate radiotherapy on a MR-linac: The dosimetric impact

The implementation of adaptive radiotherapy for prostate cancer compensates for inter-fraction motion, at the penalty of increased time in room. The subsequent increase in bladder filling may impact dosimetry, which we have investigated on ten patients treated on the MR-linac. Patients drank water before treatment, to achieve a bladder volume of 200-300 cm3. Bladder and bowel were re-outlined offline on 140 images and plans recalculated. All mandatory bladder dose constraints and 99.1% of bowel constraints were achieved at time of treatment, despite varying bladder volumes and varying adherence to original bladder filling guidance.

Bladder filling volume variation between the first and second day of planning computed tomography for prostate cancer radiation therapy and correlation with renal function

AIM

During radiation therapy (RT) for prostate cancer, bladder filling helps exclude the organ from irradiation and reduces adverse effects. For RT planning, we performed computed tomography (CT) for 2 consecutive days to evaluate inter-day variations in organs such as the bladder. However, the patient factors that are associated with large intra-patient variations in bladder filling volume prior to RT are not known.

METHODS

This was a retrospective study of 97 prostate cancer patients who underwent CT for 2 consecutive days for RT planning between March 2015 and March 2020 and with confirmed water intake volume before the scans. Patients consumed 500 ml of water immediately after urination and underwent CT 30 min after the start of water intake; CT was performed under similar conditions over 2 consecutive days. Patient information was collected from the medical records taken before CT.

RESULTS

The median bladder filling volume was 102.8 cm³ (range: 31.7-774.0), and the median intra-patient bladder filling volume variation was 23.4 cm³ (range: 0.4-277.7). Univariate analysis revealed that the intra-patient variation was significantly larger in patients with an eGFR higher than the median (p = 0.003). No other factor showed correlations with the variation. As the larger bladder filling volume of the 2 consecutive days in patients increased (median 121.5 cm³ , range: 47.8-774.0), the intra-patient variation also increased.

CONCLUSION

Patients with a higher eGFR show greater variation in bladder filling volume, and caution should be exercised when applying RT in these patients.

An environmentally friendly alternative to single-use plastics for radiotherapy bladder preparation

More than 60,000 plastic cups were used annually for bladder preparation in one radiotherapy centre. As an alternative, patients were provided with a specifically designed reusable water bottle, aiming to reduce waste and improve bladder filling compliance. Cup usage and bladder volume at treatment were calculated pre- and post-implementation. Bladder volume was measured as a percentage of the planned volume and grouped for analysis. Cup usage halved from 12,000 cups to 6000 cups. Percentage of bladder volumes in the optimal group increased from 47% to 54%. The introduction of water bottles reduced plastic cup usage and increased bladder filling compliance.

Are simple verbal instructions sufficient to ensure that bladder volume does not deteriorate prostate position reproducibility during spot scanning proton therapy?

Objectives:

The purpose of this study is to investigate whether verbal instructions are sufficient for bladder volume (BV) control not to deteriorate prostate position reproducibility in image-guided spot scanning proton therapy (SSPT) for localized prostate cancer.

Methods:

A total of 268 treatment sessions in 12 consecutive prostate cancer patients who were treated with image-guided SSPT with fiducial markers were retrospectively analyzed. In addition to strict rectal volume control procedures, simple verbal instructions to void urine one hour before the treatment were used here. The BV was measured by a Bladder Scan just before the treatment, and the prostate motion was measured by intraprostatic fiducial markers and two sets of X-ray fluoroscopy images. The correlation between the BV change and prostate motion was assessed by linear mixed-effects models and systematic and random errors according to the reproducibility of the BV.

Results:

The mean absolute BV change during treatment was from −98.7 to 86.3 ml (median 7.1 ml). The mean absolute prostate motion of the patients in the left-right direction was −1.46 to 1.85 mm; in the cranial-caudal direction it was −6.10 to 3.65 mm, and in the anteroposterior direction −1.90 to 5.23 mm. There was no significant relationship between the BV change and prostate motion during SSPT. The early and late genitourinary and gastrointestinal toxicity was minimal with a minimum follow up of 4.57 years.

Conclusions:

Simple verbal instructions about urination was suggested to be sufficient to control the BV not to impact on the prostate motion and clinical outcomes in image-guided SSPT. Careful attention to BV change is still needed when the seminal vesicle is to be treated.

Advances in knowledge:

Our data demonstrated that there was no apparent relationship between BV changes and prostate position reproducibility and simple verbal instruction about urination could be sufficient for image-guided SSPT.

Impact of bladder volume on acute genitourinary toxicity in intensity modulated radiotherapy for localized and locally advanced prostate cancer

BACKGROUND AND PURPOSE

To evaluate the effect of changes in bladder volume during high-dose intensity-modulated-radiotherapy (IMRT) of prostate cancer on acute genitourinary (GU) toxicity and prospectively evaluate a simple biofeedback technique for reproducible bladder filling with the aim of reducing acute GU toxicity.

METHODS

One hundred ninety-three patients were trained via a biofeedback mechanism to maintain a partially filled bladder with a reproducible volume of 200-300 cc at planning CT and subsequently at each fraction of radiotherapy. We prospectively analyzed whether and to what extent the patients' ability to maintain a certain bladder filling influenced the degree of acute GU toxicity and whether cut-off values could be differentiated.

RESULTS

We demonstrated that the ability to reach a reproducible bladder volume above a threshold volume of 180 cc and maintain that volume via biofeedback throughout treatment predicts for a decrease in acute GU toxicity during curative high-dose IMRT of the prostate. Patients who were not able to reach a partial bladder filling to that cut-off value and were not able to maintain a partially filled bladder throughout treatment had a significantly higher risk of developing ≥grade 2 GU acute toxicity.

CONCLUSION

Our results support the hypothesis that a biofeedback training for the patient is an easy-to-apply, useful, and cost-effective tool for reducing acute GU toxicity in high-dose IMRT of the prostate. Patients who are not able to reach and maintain a certain bladder volume during planning and treatment-two independent risk factors-might need special consideration.

Reduction of intra-fraction prostate motion - Determining optimal bladder volume and filling for prostate radiotherapy using daily 4D TPUS and CBCT

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An optimal bladder volume and filling protocol is proposed.

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The current hydration protocol was well-accepted and tolerated.

Background and purpose

Inconsistent bladder and rectal volumes have been associated with motion uncertainties during prostate radiotherapy. This study investigates the impact of these volumes to determine the optimal bladder volume.

Materials and methods

60 patients from two Asian hospitals were recruited prospectively. 1887 daily cone-beam computed tomography (CBCT) images were analysed. Intra-fraction motion of the prostate was monitored real-time using a four-dimension transperineal ultrasound (4D TPUS) Clarity® system. The impact of planned bladder volume, adequacy of daily bladder filling, and rectum volume on mean intra-fraction motion of the prostate was analysed. Patients’ ability to comply with the full bladder hydration protocol and level of frustration was assessed using a questionaire. Acute side effects were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 and quality of life (QoL) assessed using the International Prostate Symptom Score (IPSS).

Results

The mean (SD) bladder and rectum volumes achieved during daily treatment were 139.7 cm³ (82.4 cm³) and 53.3 cm³ (18 cm³) respectively. Mean (SD) percentage change from planned CT volumes in bladder volume was reduced by 8.2% (48.7%) and rectum volume was increased by 12.4% (42.2%). Linear Mixed effect model analysis revealed a reduction in intra-fraction motion in both the Sup/Inf (p = 0.008) and Ant/Post (p = 0.0001) directions when the daily bladder was filled between 82 and 113% (3rd Quartiles) of the planned CT volumes. A reduction in intra-fraction motion of the prostate in the Ant/Post direction (z-plane) (p = 0.03) was observed when the planned bladder volume was greater than 200 ml. Patients complied well with the hydration protocol with minimal frustration (mean (SD) scores of 2.1 (1.4) and 1.8 (1.2) respectively). There was a moderate positive correlation (0.496) between mean bladder volume and IPSS reported post-treatment urinary straining (p = 0.001).

Conclusions

A planned bladder volume >200 cm³ and daily filling between 82 and 113%, reduced intra-fraction motion of the prostate. The hydration protocol was well tolerated.