This preprint is under consideration at Radiation Oncology. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
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Research
Rianne de Jong
Amsterdam Universitair Medische Centra
Corresponding Author
ORCiD: https://orcid.org/0000-0003-3833-3479
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Online adaptive radiotherapy has the potential to reduce toxicity for patients treated for rectal cancer because smaller planning target volumes (PTV) margins around the entire clinical target volume (CTV) are required. The aim of this study is to describe the first clinical experience of a Conebeam CT(CBCT)-based online adaptive workflow, evaluating timing of different steps in the workflow, plan quality, target coverage and patient compliance.
Methods
Twelve consecutive patients eligible for 5 x 5 Gy pre-operative radiotherapy were treated on a ring-based linear accelerator with a multidisciplinary team present at the treatment machine for each fraction. The accelerator is operated using an integrated software platform for both treatment planning and delivery. In all directions for all CTVs a PTV margin of 5 mm was used, except for the cranial/caudal borders of the total CTV where a margin of 8mm was applied. A reference plan was generated based on a single planning CT. After aligning the patient the online adaptive procedure started with acquisition of a CBCT. The planning CT scan was registered to the CBCT using deformable registration and a synthetic CT scan was generated. With the support of artificial intelligence, structure guided deformation and the synthetic CT scan contours were adapted by the system to match the anatomy on the CBCT. If necessary, these contours were adjusted before a new plan was generated. A second and third CBCT were acquired to validate the new plan with respect to CTV coverage just before and after treatment delivery, respectively. Treatment was delivered using volumetric modulated arc treatment (VMAT). All steps in this process defined and timed.
Results
On average the timeslot needed at the treatment machine was 34 minutes. The process of acquiring a CBCT, evaluating and adjusting the contours, creating the new plan and verifying the CTV on the CBCT scan took on average 20 minutes. Including delivery and post treatment verification this was 26 minutes. Manual adjustments of the target volumes were necessary in 50% of fractions. Plan quality, target coverage and patient compliance were excellent.
Conclusions
First clinical experience with CBCT-based online adaptive radiotherapy shows it is feasible for rectal cancer.
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 (W21_087 # 21.097; Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, The Netherlands).
Keywords
Adaptive radiotherapy, Adaptive treatment, Rectal cancer, Conebeam CT
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- Supplement1.docx
Supplement 1: Check list online adaptive radiotherapy used to manage and order the steps in de workflow.
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This preprint is under consideration at Radiation Oncology. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Rianne de Jong
Amsterdam Universitair Medische Centra
Corresponding Author
ORCiD: https://orcid.org/0000-0003-3833-3479
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 1
Posted 12 Mar, 2021
No community comments so far
Review #1 received
Received 29 Mar, 2021
Reviewer #2 agreed
On 15 Mar, 2021
Reviewer #1 agreed
On 08 Mar, 2021
Reviewers invited
Invitations sent on 08 Mar, 2021
Review #? received
Received 08 Mar, 2021
First submitted
On 02 Mar, 2021
Editor assigned
On 01 Mar, 2021
Submission checks complete
On 01 Mar, 2021
Editor invited
On 01 Mar, 2021
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Online adaptive radiotherapy has the potential to reduce toxicity for patients treated for rectal cancer because smaller planning target volumes (PTV) margins around the entire clinical target volume (CTV) are required. The aim of this study is to describe the first clinical experience of a Conebeam CT(CBCT)-based online adaptive workflow, evaluating timing of different steps in the workflow, plan quality, target coverage and patient compliance.
Methods
Twelve consecutive patients eligible for 5 x 5 Gy pre-operative radiotherapy were treated on a ring-based linear accelerator with a multidisciplinary team present at the treatment machine for each fraction. The accelerator is operated using an integrated software platform for both treatment planning and delivery. In all directions for all CTVs a PTV margin of 5 mm was used, except for the cranial/caudal borders of the total CTV where a margin of 8mm was applied. A reference plan was generated based on a single planning CT. After aligning the patient the online adaptive procedure started with acquisition of a CBCT. The planning CT scan was registered to the CBCT using deformable registration and a synthetic CT scan was generated. With the support of artificial intelligence, structure guided deformation and the synthetic CT scan contours were adapted by the system to match the anatomy on the CBCT. If necessary, these contours were adjusted before a new plan was generated. A second and third CBCT were acquired to validate the new plan with respect to CTV coverage just before and after treatment delivery, respectively. Treatment was delivered using volumetric modulated arc treatment (VMAT). All steps in this process defined and timed.
Results
On average the timeslot needed at the treatment machine was 34 minutes. The process of acquiring a CBCT, evaluating and adjusting the contours, creating the new plan and verifying the CTV on the CBCT scan took on average 20 minutes. Including delivery and post treatment verification this was 26 minutes. Manual adjustments of the target volumes were necessary in 50% of fractions. Plan quality, target coverage and patient compliance were excellent.
Conclusions
First clinical experience with CBCT-based online adaptive radiotherapy shows it is feasible for rectal cancer.
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 (W21_087 # 21.097; Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, The Netherlands).
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
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