Inter-fraction movements of the prostate and pelvic lymph nodes during IGRT

Björeland, Ulrika; Jönsson, Johan; Alm, Magnus; Beckman, L.; Nyholm, Tufve; Thellenberg‐Karlsson, Camilla

doi:10.1007/s13566-018-0366-3

Cited by 10 publications

(6 citation statements)

References 30 publications

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“…During review it was noted that the prostate bed can move independently to the lymph node volumes. This has been reported previously in definitive prostate radiotherapy [ 15 ]. Our matching technique priorities matching to the prostate bed and checking that the soft tissue delineated in the lymph node CTV on the planning CT scan is included in the lymph node PTV on the CBCT scan.…”

Section: Discussionsupporting

confidence: 82%

Intra-fraction displacement of the prostate bed during post-prostatectomy radiotherapy

et al. 2021

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Background To measure intra-fraction displacement (IFD) in post-prostatectomy patients treated with anisotropic margins and daily soft tissue matching. Methods Pre-treatment cone beam computed tomography (CBCT) scans were acquired daily and post-treatment CBCTs for the first week then weekly on 46 patients. The displacement between the scans was calculated retrospectively to measure IFD of the prostate bed (PB). The marginal miss (MM) rate, and the effect of time between imaging was assessed. Results A total of 392 post-treatment CBCT’s were reviewed from 46 patients. The absolute mean (95% CI) IFD was 1.5 mm (1.3–1.7 mm) in the AP direction, 1.0 mm (0.9–1.2 mm) SI, 0.8 mm (0.7–0.9 mm) LR, and 2.4 mm (2.2–2.5 mm) 3D displacement. IFD ≥ ± 3 mm and ≥ ± 5 mm was 24.7% and 5.4% respectively. MM of the PB was detected in 33 of 392 post-treatment CBCT (8.4%) and lymph nodes in 6 of 211 post-treatment CBCT images (2.8%). Causes of MM due to IFD included changes in the bladder (87.9%), rectum (66.7%) and buttock muscles (6%). A time ≥ 9 min between the pre and post-treatment CBCT demonstrated that movement ≥ 3 mm and 5 mm increased from 19.2 to 40.5% and 5 to 8.1% respectively. Conclusions IFD during PB irradiation was typically small, but was a major contributor to an 8.4% MM rate when using daily soft tissue match and tight anisotropic margins.

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Section: Discussionsupporting

confidence: 82%

Intra-fraction displacement of the prostate bed during post-prostatectomy radiotherapy

et al. 2021

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“…Tumour and reference VOIs were transferred automatically with r + DIR techniques, from baseline diffusion-weighted image b = 200 s/mm 2 to the examination three months later, after ADT. The r + DIR technique compensated for prostate motion [25] and deformation, but also image distortions. After visual inspection of the registrations and VOIs, 16 patients had an individualised optimisation of the Elastix parameters.…”

Section: Methodsmentioning

confidence: 99%

Impact of neoadjuvant androgen deprivation therapy on magnetic resonance imaging features in prostate cancer before radiotherapy

Björeland

Nyholm

Jönsson

et al. 2021

Physics and Imaging in Radiation Oncology

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Background and purpose In locally advanced prostate cancer (PC), androgen deprivation therapy (ADT) in combination with whole prostate radiotherapy (RT) is the standard treatment. ADT affects the prostate as well as the tumour on multiparametric magnetic resonance imaging (MRI) with decreased PC conspicuity and impaired localisation of the prostate lesion. Image texture analysis has been suggested to be of aid in separating tumour from normal tissue. The aim of the study was to investigate the impact of ADT on baseline defined MRI features in prostate cancer with the goal to investigate if it might be of use in radiotherapy planning. Materials and methods Fifty PC patients were included. Multiparametric MRI was performed before, and three months after ADT. At baseline, a tumour volume was delineated on apparent diffusion coefficient (ADC) maps with suspected tumour content and a reference volume in normal prostatic tissue. These volumes were transferred to MRIs after ADT and were analysed with first-order -and invariant Haralick -features. Results At baseline, the median value and several of the invariant Haralick features of ADC, showed a significant difference between tumour and reference volumes. After ADT, only ADC median value could significantly differentiate the two volumes. Conclusions Invariant Haralick -features could not distinguish between baseline MRI defined PC and normal tissue after ADT. First-order median value remained significantly different in tumour and reference volumes after ADT, but the difference was less pronounced than before ADT.

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“…During SBRT of lymph node oligometastases on CBCT-linacs, inter-fraction motion is accounted for by couch translations and sometimes also for rotations. These translations and rotations can compensate for rigid target motion, but not for non-rigid changes of the target such as changes in size or shape or, for multiple lymph nodes, independent motion of the targets [14,15]. Additionally, it is not possible to account for anatomical changes in the location of the target and OARs, as well as path length changes and tissue attenuation.…”

Section: Introductionmentioning

confidence: 99%

Target coverage and dose criteria based evaluation of the first clinical 1.5T MR-linac SBRT treatments of lymph node oligometastases compared with conventional CBCT-linac treatment

Winkel

Bol

Werensteijn-Honingh

et al. 2020

Radiotherapy and Oncology

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a b s t r a c tBackground and purpose: Patients were treated at our institute for single and multiple lymph node oligometastases on the 1.5T MR-linac since August 2018. The superior soft-tissue contrast and additional software features of the MR-linac compared to CBCT-linacs allow for online adaptive treatment planning. The purpose of this study was to perform a target coverage and dose criteria based evaluation of the clinically delivered online adaptive radiotherapy treatment compared with conventional CBCT-linac treatment. Materials and methods: Patient data was used from 14 patients with single lymph node oligometastases and 6 patients with multiple (2-3) metastases. All patients were treated on the 1.5T MR-linac with a prescribed dose of 5 Â 7 Gy to 95% of the PTV and a CBCT-linac plan was created for each patient. The difference in target coverage between these plans was compared and plans were evaluated based on dose criteria for each fraction after calculating the CBCT-plan on the daily anatomy. The GTV coverage was evaluated based on the online planning and the post-delivery MRI. Results: For both single and multiple lymph node oligometastases the GTV V 35Gy had a median value of 100% for both the MR-linac plans and CBCT-plans pre-and post-delivery and did not significantly differ. The percentage of plans that met all dose constraints was improved from 19% to 84% and 20% to 67% for single and multiple lymph node cases, respectively. Conclusion: Target coverage and dose criteria based evaluation of the first clinical 1.5T MR-linac SBRT treatments of lymph node oligometastases compared with conventional CBCT-linac treatment shows a smaller amount of unplanned violations of high dose criteria. The GTV coverage was comparable. Benefit is primarily gained in patients treated for multiple lymph node oligometastases: geometrical deformations are accounted for, dose can be delivered in one plan and margins can be reduced.

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Inter-fraction movements of the prostate and pelvic lymph nodes during IGRT

Cited by 10 publications

References 30 publications

Intra-fraction displacement of the prostate bed during post-prostatectomy radiotherapy

Intra-fraction displacement of the prostate bed during post-prostatectomy radiotherapy

Impact of neoadjuvant androgen deprivation therapy on magnetic resonance imaging features in prostate cancer before radiotherapy

Target coverage and dose criteria based evaluation of the first clinical 1.5T MR-linac SBRT treatments of lymph node oligometastases compared with conventional CBCT-linac treatment

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