Associations between volume changes and spatial dose metrics for the urinary bladder during local versus pelvic irradiation for prostate cancer

Casares-Magaz, Oscar; Moiseenko, Vitali; Hopper, Austin; Pettersson, Niclas; Thor, Maria; Knopp, Rick; Deasy, Joseph O.; Muren, L.P.; Einck, John

doi:10.1080/0284186x.2017.1312014

Cited by 24 publications

(28 citation statements)

References 29 publications

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“…And MR-biomonitoring and adaptive treatment are currently evolving in prostate cancer and other tumor entities [7]. Reduction of the planning target volume (PTV) margins due to improved definition of the prostate including dominant lesions, i.e., the intraprostatic tumor by MRI or PET [8], is impeded by inter-and intrafractional organ movements of prostate and surrounding organs at risk (OAR) like bowel and bladder volume changes [9,10].…”

Section: Introductionmentioning

confidence: 99%

Precision of T2 TSE MRI-CT-image fusions based on gold fiducials and repetitive T2 TSE MRI-MRI-fusions for adaptive IGRT of prostate cancer by using phantom and patient data

et al. 2018

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2019) Precision of T2 TSE MRI-CT-image fusions based on gold fiducials and repetitive T2 TSE MRI-MRI-fusions for adaptive IGRT of prostate cancer by using phantom and patient data, Acta Oncologica, 58:1, 88-94, ABSTRACT Introduction: To increase precision of radiation treatment (RT) delivery in prostate cancer, MRI-based RT as well as the use of fiducials like gold markers (GMs) have shown promising results. Their combined use is currently under investigation in clinical trials. Here, we aimed to evaluate a workflow of image registration based on GMs between CT and MRI as well as weekly MRI-MRI adaption based on T2 TSE sequence. Material and methods: A gel-phantom with two inserted GMs was scanned with CT and three different MR-scanners of 1.5 and 3 T (T2 TSE and T1 VIBE-Dixon, isotropic, voxel size 2 Â 2 Â 2 mm). After image fusion, deviations for fiducial and gel match were measured and artifacts were evaluated. Additionally, CT-MRI-match deviations and MRI-MRI-match deviations of 10 Patients from the M-basePro study using GMs were assessed. Results: GMs were visible in all imaging modalities. The outer gel contours were matched with <1 mm deviation, contour volumes varied between 0 and 1%. The deviations of the GMs were less than 2 mm in any direction of MRI/CT. Shifts of peripherally or centrally located GMs were randomly distributed. The average MRI-CT-match precision of 10 patients with GMs was 1.9 mm (range 1.1-3.1 mm). Conclusions: Match inaccuracies for GMs between reference CT and voxel-isotropic T2-TSE sequences are small. Spatial deviations of CT-and MR-contoured fiducials were less than 2 mm, i.e., below SLT of the applied modalities. In patients, the average CT-MRI-match precision for GMs was 1.9 mm supporting their use in MR-guided high precision RT. ARTICLE HISTORY

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Section: Introductionmentioning

confidence: 99%

Precision of T2 TSE MRI-CT-image fusions based on gold fiducials and repetitive T2 TSE MRI-MRI-fusions for adaptive IGRT of prostate cancer by using phantom and patient data

et al. 2018

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“…On the other hand, changes in bladder filling, shape and position during the RT course have been extensively reported [12,14,16,30], and are major reasons for the differences between planned and delivered DVH metrics [13]. In the previous study, we also demonstrated that the posterior/inferior bladder wall tended to move towards the high dose region when the bladder volume increased [22]. In the present study, we observed larger delivered bladder volumes compared to planned for cases, and smaller delivered compared to planned for controls (Fig.…”

Section: Discussionmentioning

confidence: 54%

A case-control study using motion-inclusive spatial dose-volume metrics to account for genito-urinary toxicity following high-precision radiotherapy for prostate cancer

Casares-Magaz

Muren

Pettersson

et al. 2018

Physics and Imaging in Radiation Oncology

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Background and purpose: The risk of genitourinary (GU) toxicity is dose-limiting in radiotherapy (RT) for prostate cancer. This study investigated whether motion-inclusive spatial dose/volume metrics explain the GU toxicity manifesting after high-precision RT for prostate cancer. Material and methods: A matched case-control was performed within a cohort of 258 prostate cancer patients treated with daily cone-beam CT (CBCT)-guided RT (prescription doses of 77.4-81.0 Gy). Twenty-seven patients (10.5%) presented late RTOG GU ≥ Grade 2 toxicity and those without symptoms of toxicity prior treatment (N = 7) were selected as cases. Each case was matched with three controls based on pre-treatment GU symptoms, age, Gleason score, follow-up time, and hormone therapy. Thirteen CBCTs per patient were rigidly registered to the planning CT using the recorded treatment shifts, and the bladder was manually contoured on each CBCT. Planned and actually delivered dose/volume metrics (the latter averaged across the CBCTs) were extracted from the bladder and its subsectors, and compared between cases and controls (two-way ANOVA test). Results: There were no significant differences between planned and delivered dose/volume metrics; also, there were no significant differences between cases and controls at any dose level, neither for planned nor delivered doses. The cases tended to have larger bladder volumes during treatment than controls (221 ± 71 cm 3 vs 166 ± 73 cm 3 ; p = 0.09). Conclusions: High-precision RT for prostate cancer eliminates differences between planned and delivered dose distributions. Neither planned nor delivered bladder dose/volume metrics were associated to the remaining low risk of developing GU toxicity after high-precision radiotherapy for prostate cancer.

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“…Treatment could be interrupted or adapted if intra-fraction motion exceeded a certain threshold. This could be addressed by electromagnetic transponders, for example using the Calypso system for prostate radiotherapy, or by MRI-delivered treatments such as the MR-Linac [37,56]. However, the additional equipment and need for implantation may limit more general use of electromagnetic transponders and the complexities of rapid daily adaptive replanning at present represents a challenge to the routine use of the MR-Linac.…”

Section: Discussionmentioning

confidence: 99%

“…In prostate radiotherapy, implanted electromagnetic transponders such as the Calypso 4D localisation system (Calypso Medical Technologies, Seattle, USA) can monitor for interfractional changes in prostate position [37]. In addition, these also permit real time tracking, providing the potential to correct for intra-fractional prostate motion and gating of the radiation beam if intra-fraction motion exceeds a certain threshold.…”

Section: Electromagnetic Transpondersmentioning

confidence: 99%

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Overview of patient preparation strategies to manage internal organ motion during radiotherapy in the pelvis

Slevin

Beasley²,

Speight³

et al. 2019

J Radiother Pract

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Introduction:Pelvic internal organs change in volume and position during radiotherapy. This may compromise the efficacy of treatment or worsen its toxicity. There may be limitations to fully correcting these changes using online image guidance; therefore, effective and consistent patient preparation and positioning remain important. This review aims to provide an overview of the extent of pelvic organ motion and strategies to manage this motion.Methods and Materials:Given the breadth of this topic, a systematic review was not undertaken. Instead, existing systematic reviews and individual high-quality studies addressing strategies to manage pelvic organ motion have been discussed. Suggested levels of evidence and grades of recommendation for each strategy have been applied.Results:Various strategies to manage rectal changes have been investigated including diet and laxatives, enemas and rectal emptying tubes and rectal displacement with endorectal balloons (ERBs) and rectal spacers. Bladder-filling protocols and bladder ultrasound have been used to try to standardise bladder volume. Positioning the patient supine, using a full bladder and positioning prone with or without a belly board, has been examined in an attempt to reduce the volume of irradiated small bowel. Some randomised trials have been performed, with evidence to support the use of ERBs, rectal spacers, bladder-filling protocols and the supine over prone position in prostate radiotherapy. However, there was a lack of consistent high-quality evidence that would be applicable to different disease sites within the pelvis. Many studies included small numbers of patients were non-randomised, used less conformal radiotherapy techniques or did not report clinical outcomes such as toxicity.Conclusions:There is uncertainty as to the clinical benefit of many of the commonly adopted interventions to minimise pelvic organ motion. Given this and the limitations in online image guidance compensation, further investigation of adaptive radiotherapy strategies is required.

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Associations between volume changes and spatial dose metrics for the urinary bladder during local versus pelvic irradiation for prostate cancer

Cited by 24 publications

References 29 publications

Precision of T2 TSE MRI-CT-image fusions based on gold fiducials and repetitive T2 TSE MRI-MRI-fusions for adaptive IGRT of prostate cancer by using phantom and patient data

Precision of T2 TSE MRI-CT-image fusions based on gold fiducials and repetitive T2 TSE MRI-MRI-fusions for adaptive IGRT of prostate cancer by using phantom and patient data

A case-control study using motion-inclusive spatial dose-volume metrics to account for genito-urinary toxicity following high-precision radiotherapy for prostate cancer

Overview of patient preparation strategies to manage internal organ motion during radiotherapy in the pelvis

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