Consistency of Organ Geometries during Prostate Radiotherapy with Two Different Bladder and Bowel Regimens

Yaver, Mina; Foo, Ann; Larsen, Tessa; Fineberg, Heather; Zeng, Guanggen; McGowan, Thomas; Jones, Glenn

doi:10.1016/j.jmir.2015.09.001

Cited by 10 publications

(14 citation statements)

References 22 publications

(31 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although previous studies seeking to find an optimal bladder and rectal state for prostate radiotherapy have not found significant differences in the intra‐fractional prostate displacement between plans that were designed for patients with full and empty bladders, they have not investigated displacement and change in the dose to the prostate between extreme bladder states. Our results showed that changes in the bladder volume can lead to large, systematic displacements in the prostate and SVs.…”

Section: Discussionmentioning

confidence: 99%

Geometric and dosimetric impact of anatomical changes for MR‐only radiation therapy for the prostate

Nejad-Davarani¹,

Sevak

Moncion

et al. 2019

J Applied Clin Med Phys

View full text Add to dashboard Cite

Purpose With the move towards magnetic resonance imaging (MRI) as a primary treatment planning modality option for men with prostate cancer, it becomes critical to quantify the potential uncertainties introduced for MR‐only planning. This work characterized geometric and dosimetric intra‐fractional changes between the prostate, seminal vesicles (SVs), and organs at risk (OARs) in response to bladder filling conditions. Materials and methods T2‐weighted and mDixon sequences (3–4 time points/subject, at 1, 1.5 and 3.0 T with totally 34 evaluable time points) were acquired in nine subjects using a fixed bladder filling protocol (bladder void, 20 oz water consumed pre‐imaging, 10 oz mid‐session). Using mDixon images, Magnetic Resonance for Calculating Attenuation (MR‐CAT) synthetic computed tomography (CT) images were generated by classifying voxels as muscle, adipose, spongy, and compact bone and by assignment of bulk Hounsfield Unit values. Organs including the prostate, SVs, bladder, and rectum were delineated on the T2 images at each time point by one physician. The displacement of the prostate and SVs was assessed based on the shift of the center of mass of the delineated organs from the reference state (fullest bladder). Changes in dose plans at different bladder states were assessed based on volumetric modulated arc radiotherapy (VMAT) plans generated for the reference state. Results Bladder volume reduction of 70 ± 14% from the final to initial time point (relative to the final volume) was observed in the subject population. In the empty bladder condition, the dose delivered to 95% of the planning target volume (PTV) (D95%) reduced significantly for all cases (11.53 ± 6.00%) likely due to anterior shifts of prostate/SVs relative to full bladder conditions. D15% to the bladder increased consistently in all subjects (42.27 ± 40.52%). Changes in D15% to the rectum were patient‐specific, ranging from −23.93% to 22.28% (−0.76 ± 15.30%). Conclusions Variations in the bladder and rectal volume can significantly dislocate the prostate and OARs, which can negatively impact the dose delivered to these organs. This warrants proper preparation of patients during treatment and imaging sessions, especially when imaging required longer scan times such as MR protocols.

show abstract

Section: Discussionmentioning

confidence: 99%

Geometric and dosimetric impact of anatomical changes for MR‐only radiation therapy for the prostate

Nejad-Davarani¹,

Sevak

Moncion

et al. 2019

J Applied Clin Med Phys

View full text Add to dashboard Cite

show abstract

“…Diet as a method of managing rectal variation has been investigated with mixed results. [26][27][28][29] Looking to influence the rectal volume and the presence of gas with dietary advice proved unfeasible in our local, small group study of patients receiving bladder radiotherapy. In total, 80% of patients self-identified comorbidity that required them to follow a specific diet.…”

Section: Study Rationalementioning

confidence: 97%

“…– 25 Micro-enemas have been used as standard practice within the author’s department for 15 years, and the assessment of patient suitability is made using Patient Group Directives. Diet as a method of managing rectal variation has been investigated with mixed results 26 29 Looking to influence the rectal volume and the presence of gas with dietary advice proved unfeasible in our local, small group study of patients receiving bladder radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

A feasibility study for the introduction of micro-enema to improve organ consistency in patients receiving radiotherapy for urinary bladder cancer

et al. 2017

View full text Add to dashboard Cite

AimsThe aim of the study was to assess the effect on rectal consistency, of introducing a micro-enema in the preparation of patients receiving radiotherapy treatment of urinary bladder cancer.Materials and methodsThe treatment cone beam computed tomography (CBCT) images from patients receiving radiotherapy for bladder cancer were retrospectively assessed. CBCT datasets from nine patients treated without rectal preparation (97 CBCT), and 13 patients (134 CBCT) treated following micro-enema use before planning and treatment were evaluated. CBCT were compared with the planning computed tomography for rectal status, rectal diameter and presence of gas.ResultsReproducibility of an empty rectum was achieved in 70% of treatment fractions delivered using an enema protocol compared with 33% of fractions delivered without preparation. In total, 10% of fractions were delivered with the presence of faeces or faeces and gas, compared with 46% of fractions for the non-intervention group. Enemas did not affect the proportion of fractions delivered with gas, however, where gas was present, 65% of CBCT fractions had <5% gas for patients using enemas compared with 32% without.FindingsThe use of a micro-enema before planning scan and each fraction was well tolerated and proved effective in managing and reducing inter-fraction variations in rectal volume and contents.

show abstract

“…However, this protocol is not used in our department. Yaver et al indicated that bladder and rectum preparation can influence the geometries and volume of both organs and affect dose exposures and toxicities [17], and others indicated possible dosimetric variations affecting normal tissue complication probability [18,19,20]. The introduction of image guidance techniques using kilovoltage (kV/kV) and gold fiducial markers or kilovoltage conebeam computed tomography (kV-CBCT) imaging has brought about a reduction in toxicity [21] and help in finding out the daily variation in bladder and rectum volume due to variable filling during the course of treatment [22].…”

Section: Introductionmentioning

confidence: 99%

In vivo dosimetry for patients with prostate cancer to assess possible impact of bladder and rectum preparation

Fiagan

Bossuyt

Nevens

et al. 2020

Technical Innovations & Patient Support in Radiation Oncolo

View full text Add to dashboard Cite

In all treatment sites of our radiotherapy network, in vivo dosimetry (PerFRACTION TM) was fully implemented in February 2018. We hypothesized that additional help with bladder and rectum preparation by home nursing would improve patients' preparation and investigated if this could be assessed using in vivo dosimetry (IVD). Materials/methods: A retrospective study was conducted with a test group who received additional help with bladder and rectum preparation by home nurses and a control group who only received information on bladder and rectum preparation according to the standard protocol. Patients were treated with a 6 MV Volumetric Modulated Arc Therapy (VMAT) technique. Electronic portal imaging device (EPID)-based integrated transit dose images were acquired on the first 3 days of treatment and weekly thereafter or more if failed fractions (FF) occurred. Results were analyzed using a global gamma analysis with a threshold of 20%, tolerance of 5% (dose difference) and 5 mm (distance to agreement), and a passing level of 95%. Results: Data of 462 prostate patients was analyzed: 39 and 423 in a test and control group respectively with a comparable number of measurements (on average 8.0 (r = 4.8) and 7.1 (r = 4.5) respectively per treatment course). Of the FF, 39% and 31% were related to variations in bladder and rectum filling for the test and control group respectively. Subgroups were created based on the number of FF, no statistically significant differences were observed. Conclusion: Two dimensional EPID-based IVD successfully detected deviations due to variations in bladder and rectum filling, however it could not confirm the hypothesis.

show abstract

Consistency of Organ Geometries during Prostate Radiotherapy with Two Different Bladder and Bowel Regimens

Cited by 10 publications

References 22 publications

Geometric and dosimetric impact of anatomical changes for MR‐only radiation therapy for the prostate

Geometric and dosimetric impact of anatomical changes for MR‐only radiation therapy for the prostate

A feasibility study for the introduction of micro-enema to improve organ consistency in patients receiving radiotherapy for urinary bladder cancer

In vivo dosimetry for patients with prostate cancer to assess possible impact of bladder and rectum preparation

Contact Info

Product

Resources

About