Target volume shape variation during irradiation of rectal cancer patients in supine position: Comparison with prone position

Nijkamp, Jasper; Jong, Rianne de; Sonke, Jan‐Jakob; Vliet, Corine van; Marijnen, Corrie A.M.

doi:10.1016/j.radonc.2009.08.007

Cited by 54 publications

(41 citation statements)

References 22 publications

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“…Since the bladder position, bladder shape, and the bladder deformation vary between both the gender of the patient and its treatment position, 7,29,31 the data of these patients were divided into four equally sized subgroups based on gender and treatment position (Table I). Each patient had a median (min-max) of seven (5-9) CBCT images, all acquired for position verification purposes.…”

Section: A Patient Datamentioning

confidence: 99%

“…The pelvic region contains several organs, e.g., bladder, rectum, and cervix-uterus or prostate, with large daily variation in size and position during fractionated radiation therapy (RT). [3][4][5][6][7] To compensate for these geometrical uncertainties, large safety margins around the target volume have to be applied. 8,9 However, these margins result in a high dose to surrounding healthy tissue and are in some cases even insufficient.…”

Section: Introductionmentioning

confidence: 99%

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Generic method for automatic bladder segmentation on cone beam CT using a patient‐specific bladder shape model

et al. 2014

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Section: A Patient Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Generic method for automatic bladder segmentation on cone beam CT using a patient‐specific bladder shape model

et al. 2014

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“…Due to the inevitable dose to organs at risk (OAR) such as the small bowel and bladder, radiation therapy for rectum cancer is associated with toxicity [1]. While treatmentplanning techniques with intensity modulation (IMRT/ VMAT) make it possible to reduce the dose to OARs by steep dose gradients, the benefit is counteracted by the large population-based margins that are necessary to compensate for large inter-fraction shape-changes caused by changing rectum and bladder filling [2][3][4][5][6]. Drinking protocols to stabilize the volume of the bladder have had only limited success [7,8].…”

Section: Introductionmentioning

confidence: 99%

Dosimetric benefit of an adaptive treatment by means of plan selection for rectal cancer patients in both short and long course radiation therapy

et al. 2020

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Background: To compare target coverage and dose to the organs at risk in two approaches to rectal cancer: a clinically implemented adaptive radiotherapy (ART) strategy using plan selection, and a non-adaptive (non-ART) strategy. Methods: The inclusion of the first 20 patients receiving adaptive radiotherapy produced 10 patients with a long treatment schedule (25x2Gy) and 10 patients with a short schedule (5X5Gy). We prepared a library of three plans with different anterior PTV margins to the upper mesorectum, and selected the most appropriate plan on daily Conebeam CT scans (CBCT). We also created a non-adaptive treatment plan with a 20 mm margin. Bowel bag, bladder and target volume were delineated on CBCT. Daily DHVs were calculated based on the dose distribution of the selected and non-adaptive plans. Coverage of the target volume was compared per fraction between the ART and non-ART plans, as was the dose to the bladder and small bowel, assessing the following dose levels: V15Gy, V30Gy, V40Gy, V15Gy and V95% for long treatment schedules, and V15Gy and V95% for short ones. Results: Target volume coverage was maintained from 98.3% (non-ART) to 99.0% (ART)(p = 0.878). In the small bowel, ART appeared to have produced significant reductions in the long treatment schedule at V15Gy, V40Gy, V45Gy and V95% (p < 0.05), but with small absolute differences. The DVH parameters tested for the short treatment schedule did not differ significantly. In the bladder, all DVH parameters in both schedules showed significant reductions (p < 0.05), also with small absolute differences. Conclusions: The adaptive treatment maintained target coverage and reduced dose to the organs at risk. Trial registration: Medical Research Involving Human Subjects Act (WMO) does not apply to this study and was retrospectively approved by the Medical Ethics review Committee of the Academic Medical Center, W19_194 # 19.233.

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“…A remark must been made that the data Nijkamp et al reported was based on patients lying prone, clinically our patients where lying supine. Nijkamp concluded in another study that there are differences between supine and prone orientation, but they are small [25].…”

Section: Discussionmentioning

confidence: 95%

Pre-clinical experience of an adaptive plan library strategy in radiotherapy of rectal cancer: An inter-observer study

Beek

Betgen

Buijs

et al. 2018

Physics and Imaging in Radiation Oncology

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Background and purpose: The clinical target volume (CTV) in radiotherapy of rectal cancer is subject to large deformations. With a plan library strategy, the treatment may be adapted to these deformations. The purpose of this study was to determine feasibility and consistency in plan selection for a plan library strategy in radiotherapy of rectal cancer. Material and methods: Thirty rectal cancer patients were included in this retrospective study with in total 150 CBCT scans. A library of CTVs was constructed with in-house built software using population statistics on daily rectal deformations. The library consisted of five plans based on: the original CTV, two larger, and two smaller CTVs. An inter-observer study (study-I) was performed to test the consistency in plan choices between four observers (all RTTs). After five months the observers were asked to re-evaluate (study-II) the same set of scans based on refined guidelines. Results: In study-I the observers reached accordance with the majority choice in 69% of cases. This improved to 87% in study-II. The consensus meeting revealed that inconsistency in choices mainly arose from inadequate instructions, which were later clarified and formulated more accurately. Conclusion: Plan selection based on daily CBCT scans for rectal cancer patients is feasible, and can be performed consistently by well-trained RTTs.

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Target volume shape variation during irradiation of rectal cancer patients in supine position: Comparison with prone position

Cited by 54 publications

References 22 publications

Generic method for automatic bladder segmentation on cone beam CT using a patient‐specific bladder shape model

Generic method for automatic bladder segmentation on cone beam CT using a patient‐specific bladder shape model

Dosimetric benefit of an adaptive treatment by means of plan selection for rectal cancer patients in both short and long course radiation therapy

Pre-clinical experience of an adaptive plan library strategy in radiotherapy of rectal cancer: An inter-observer study

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