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

Pang, Eric Pei Ping; Knight, Kellie; Hussain, Ashik; Fan, Qiao; Baird, Marilyn; Tan, Sheena Xue Fei; Mui, Wing Ho; Leung, R; Seah, Irene Kai Ling; Master, Zubin; Tuan, Jeffrey Kit Loong

doi:10.1016/j.tipsro.2018.01.003

Cited by 17 publications

(19 citation statements)

References 24 publications

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“…While the prostate is shifted anteriorly in most cases as the bladder volume is reduced, in some cases, posterior shift is observed. These findings match the results of a recent study based on analysis of CBCT and four‐dimensional (4D) trans‐perineal ultrasound (4D TPUS) measurements of 60 patients that showed intra‐fractional motion of the prostate in the A‐P and S‐I directions . In this study, reduction of A‐P motion of the prostate was observed when the planned bladder volume was greater than 200 ml.…”

Section: Discussionsupporting

confidence: 90%

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

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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.

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Section: Discussionsupporting

confidence: 90%

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

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“…Ensure adequate bladder filling (>200 cm 3 ) (practice is dependent on departmental workflow). 13 8. Reduce the time lapse between the CT/TPUS images by acquiring the TPUS images immediately before or immediately after the final CT scan to avoid gross movement which may affect subsequent registration of the CT/TPUS images.…”

Section: Perform a Cone-down Volume Of The Ct Scan To Checkmentioning

confidence: 99%

Technical considerations for positioning and placement of a transperineal ultrasound probe during prostate radiotherapy

Pang

Knight

Leung

et al. 2020

J of Medical Radiation Sci

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This technical evaluation aims to provide practice 'how to' guidelines for radiation therapists (RTs) when positioning a transperineal ultrasound (TPUS) probe during prostate radiotherapy. Recommendations and practical tips will be provided for the best practice in TPUS-guided workflow to obtain optimal ultrasound images for accurate interpretation and registration of the prostate gland. This will assist the RTs in making consistent and accurate clinical decision in an ultrasound-guided radiotherapy workflow for prostate treatment. The implementation process and the associated successes and challenges will also be described to assist institutions who may be investigating the potential of implementing this system.

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“…In addition, the impact of UV changes on prostate position during radiotherapy is not commonly agreed on. Some studies have concluded that the UV changes during treatment correlated with the displacement of the prostate [7][8][9][10][11][12], while others found no such correlation [4,[17][18][19]. We hypothesized that the prostate volume (PV) could also be related to the susceptibility of prostate movement due to changes in UV, however, there is no report of details of this relationship.…”

Section: Introductionmentioning

confidence: 96%

“…One of the main factors in the changes of the position of the prostate during radiotherapy is the change in urinary volume (UV) in the bladder [7][8][9][10][11][12]. Considerations to keep UV constant during radiotherapy are widely recommended [6,[13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

The Impact of Daily Urinary Volume Variations and Prostate Volume on Prostate Position During Radiotherapy

Nishioka¹,

Hashimoto²,

Abe³

et al. 2020

Preprint

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BackgroundDaily variations in bladder volumes are thought to be a major cause of prostate position changes during radiotherapy, however, the impact of such changes on prostate position is not fully established. We hypothesized that prostate volume (PV) could also be related to the susceptibility of prostate movement to changes in urinary volume (UV). The purpose of this study is to investigate the impact of daily UV variations and PV on the prostate position during radiotherapy.MethodsA total of 268 treatment sessions in 12 consecutive prostate cancer patients who were treated with proton beam therapy in our hospital were retrospectively analyzed. All patients were instructed to void urine and feces one hour before the treatment and the UV was measured by a portable ultrasound device just before the treatment. After the positional registration based on bone structure, the prostate positional difference from the planned position was measured using fiducial markers in the prostate and a real-time tumor tracking system. The measurements were for the differences in the left-right (LR), cranial-caudal (CC), and anterior-posterior (AP) directions. The PV was measured by ultrasound imaging before every treatment. The impact of the UV variations on the prostate position was evaluated by the linear mixed effect model, and including PV (<20ml and ≥20ml) as covariates. ResultsThere was significant movement of the prostate in the posterior direction with increasing UV in patients with PV ≥ 20 ml (p=0.04, estimated coefficient of regression -0.436 mm/100ml, 95% CI from -0.854 to -0.018). However, there was no significant correlation between UV changes and movement of the prostate in either of the LR, CC, or AP directions in all cases and patients with PV < 20 ml.ConclusionsOur results suggest that the increase of UV could result in posterior prostate movement in patients with prostatic hyperplasia, however, the clinical impact is thought to be small. There is however a need for further research to identify other factors that could affect the daily changes in prostate position as well as a need for a more ideal preparation protocol to improve the reproducibility of the treatment-planning CT.

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

Cited by 17 publications

References 24 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

Technical considerations for positioning and placement of a transperineal ultrasound probe during prostate radiotherapy

The Impact of Daily Urinary Volume Variations and Prostate Volume on Prostate Position During Radiotherapy

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