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Use of a prospective cohort study in the development of a bladder scanning protocol to assist in bladder filling consistency for prostate cancer patients receiving radiation therapy

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Evidence of variations in bladder filling effecting prostate stability and therefore treatment and side‐effects is well established with intensity modulated radiation therapy (IMRT). This study aimed to increase bladder volume reproducibility for prostate radiation therapy by implementing a bladder scanning (BS) protocol that could assist patients' bladder filling at computed tomography (CT) simulation and treatment.

Methods: Based on a retrospective review of 524 prostate cancer patients, a bladder volume of 250–350 mL was adopted as ‘ideal’ for achieving planning dose constraints. A prospective cohort study was conducted to assess the clinical utility of measuring patients' bladder volumes at CT simulation using an ultrasound bladder scanner (Verathon 9400 BladderScan®). A revised bladder preparation protocol was utilised by a bladder scan group (BS) and a non‐BS group followed the standard departmental bladder preparation protocol. Time and volume data for the BS group (n = 17) were compared with the non‐BS group (n = 17).

Results: The BS cohort had a CT bladder volume range of 221–588 mL; mean 379 mL, SD 125 mL. The non‐BS group had a larger range: 184–757 mL; mean 373 mL, SD 160 mL (P = 0.9171). There was a positive correlation between CT volume and BS volume in the BS group (r = 0.797; P = 0.0002) although BS volumes were smaller: range 160–420 mL; mean 251 mL; SD 91 mL; P < 0.0001). The maximum bladder volume receiving 50 Gy (V50) from the BS group was 46.4%, mean 24.5%. The maximum bladder V50 from the non‐BS group was 50.9%, mean 27.3% (P = 0.5178). Treatment data from weekly cone beam CT scans were also compared over 6 weeks. They were assessed as being a pass if bladder and bowel requirements were acceptable. The BS group proceeded to treatment on the basis of a pass 92.7% of the time, whereas the pass rate for non‐BS group was 75%; difference 17.7% (P < 0.0001).

Conclusion: The BS is a useful tool for achieving consistent, appropriately sized bladder volumes in prostate cancer patients.

No MeSH data available.


Protocol for bladder filling using the BS at simulation during the prospective study. BS, bladder scanner; CT, computed tomography.
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jmrs162-fig-0003: Protocol for bladder filling using the BS at simulation during the prospective study. BS, bladder scanner; CT, computed tomography.

Mentions: All patients were treated with curative intent and standard dose of 81 Gy in 45# for high and intermediate prostates and 66 Gy/33# for post‐prostatectomies. Sequentially allocated, seventeen cases, referred to as the non‐BS group followed the standard departmental bladder and bowel preparation. Patients were asked to empty their bladder and bowels one hour prior to their simulation appointment and to drink 600 mL (3 cups) of water immediately. Patients were CT scanned at their appointment time if they verbally confirmed their bladder felt full. The seventeen cases in the BS group followed the same protocol as the feasible study. The first BS was performed 30 min post‐drinking and repeated as per Figure 3. The same volume and time data points collected during the feasibility study were recorded for the prospective study in an Excel spread sheet. Based on experiences from the feasibility study, it was deemed necessary to generalise the treatment comments to render them useful for analysis. Staff were re‐educated in the required CBCT review process and then asked to consistently format the CBCT comments according to the following template: ‘Bladder = (1/4, 1/2, ¾, more than or =) planned, rectum = (good; too much gas; too much matter), move = (>, < or =) 3 mm, (+/− Patient. re‐educated)’. The CBCT comments were categorised into either a ‘pass’ or ‘fail’ status based on treatment acceptability as referred to in the results section. The CBCT review process had already been established as a quick subjective assessment of key parameters of isocentre position, rectum status and bladder status. The requirements of the BS study added further formalisation of the CBCT review process and provided a more rigorous documentation and categorisation which became normal clinical practice. The image assessment is still a subjective interpretation and is not a hard measurement based process nor is one needed, as it is not critical to the BS study outcomes. Comments were then categorised into five groups (Table 2) with three groups proceeding to treatment (a ‘pass’) and two groups classified as a ‘fail’.


Use of a prospective cohort study in the development of a bladder scanning protocol to assist in bladder filling consistency for prostate cancer patients receiving radiation therapy
Protocol for bladder filling using the BS at simulation during the prospective study. BS, bladder scanner; CT, computed tomography.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016618&req=5

jmrs162-fig-0003: Protocol for bladder filling using the BS at simulation during the prospective study. BS, bladder scanner; CT, computed tomography.
Mentions: All patients were treated with curative intent and standard dose of 81 Gy in 45# for high and intermediate prostates and 66 Gy/33# for post‐prostatectomies. Sequentially allocated, seventeen cases, referred to as the non‐BS group followed the standard departmental bladder and bowel preparation. Patients were asked to empty their bladder and bowels one hour prior to their simulation appointment and to drink 600 mL (3 cups) of water immediately. Patients were CT scanned at their appointment time if they verbally confirmed their bladder felt full. The seventeen cases in the BS group followed the same protocol as the feasible study. The first BS was performed 30 min post‐drinking and repeated as per Figure 3. The same volume and time data points collected during the feasibility study were recorded for the prospective study in an Excel spread sheet. Based on experiences from the feasibility study, it was deemed necessary to generalise the treatment comments to render them useful for analysis. Staff were re‐educated in the required CBCT review process and then asked to consistently format the CBCT comments according to the following template: ‘Bladder = (1/4, 1/2, ¾, more than or =) planned, rectum = (good; too much gas; too much matter), move = (>, < or =) 3 mm, (+/− Patient. re‐educated)’. The CBCT comments were categorised into either a ‘pass’ or ‘fail’ status based on treatment acceptability as referred to in the results section. The CBCT review process had already been established as a quick subjective assessment of key parameters of isocentre position, rectum status and bladder status. The requirements of the BS study added further formalisation of the CBCT review process and provided a more rigorous documentation and categorisation which became normal clinical practice. The image assessment is still a subjective interpretation and is not a hard measurement based process nor is one needed, as it is not critical to the BS study outcomes. Comments were then categorised into five groups (Table 2) with three groups proceeding to treatment (a ‘pass’) and two groups classified as a ‘fail’.

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Evidence of variations in bladder filling effecting prostate stability and therefore treatment and side&#8208;effects is well established with intensity modulated radiation therapy (IMRT). This study aimed to increase bladder volume reproducibility for prostate radiation therapy by implementing a bladder scanning (BS) protocol that could assist patients' bladder filling at computed tomography (CT) simulation and treatment.

Methods: Based on a retrospective review of 524 prostate cancer patients, a bladder volume of 250&ndash;350 mL was adopted as &lsquo;ideal&rsquo; for achieving planning dose constraints. A prospective cohort study was conducted to assess the clinical utility of measuring patients' bladder volumes at CT simulation using an ultrasound bladder scanner (Verathon 9400 BladderScan&reg;). A revised bladder preparation protocol was utilised by a bladder scan group (BS) and a non&#8208;BS group followed the standard departmental bladder preparation protocol. Time and volume data for the BS group (n = 17) were compared with the non&#8208;BS group (n = 17).

Results: The BS cohort had a CT bladder volume range of 221&ndash;588 mL; mean 379 mL, SD 125 mL. The non&#8208;BS group had a larger range: 184&ndash;757 mL; mean 373 mL, SD 160 mL (P = 0.9171). There was a positive correlation between CT volume and BS volume in the BS group (r = 0.797; P = 0.0002) although BS volumes were smaller: range 160&ndash;420 mL; mean 251 mL; SD 91 mL; P &lt; 0.0001). The maximum bladder volume receiving 50 Gy (V50) from the BS group was 46.4%, mean 24.5%. The maximum bladder V50 from the non&#8208;BS group was 50.9%, mean 27.3% (P = 0.5178). Treatment data from weekly cone beam CT scans were also compared over 6 weeks. They were assessed as being a pass if bladder and bowel requirements were acceptable. The BS group proceeded to treatment on the basis of a pass 92.7% of the time, whereas the pass rate for non&#8208;BS group was 75%; difference 17.7% (P &lt; 0.0001).

Conclusion: The BS is a useful tool for achieving consistent, appropriately sized bladder volumes in prostate cancer patients.

No MeSH data available.