Active, Not Recruiting

NCT Number: NCT07083648

Magnetic Resonance Imaging-guided Online Adaptive Radiotherapy of Pelvic Lymph Node Metastases

In this study, the investigators want to investigate whether online-adapted radiotherapy using a special magnetic resonance imaging (MRI) simulator and computed tomography (CT)-guided radiation therapy, is feasible and offers advantages for the treatment of pelvic lymph node metastases.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

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Key information

Conditions

Pelvic and Para-aortic Lymph Node Metastases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Zurich University Hospital, Department of Radiation Oncology

Zurich, Canton of Zurich, 8091, Switzerland

About this study

MR-guided online adaptive radiotherapy has been implemented recently using MR-linac technology, where MR-imaging is combined with linac technology in hybrid systems. These systems offer MR imaging for online adaptive radiotherapy (RT) within the treatment room and with the patient in treatment position. Despite results regarding technical and clinical feasibility being promising, the high costs of MR-linacs systems and the high demands for staffing resources of MR-linacs are limiting a boarder implementation of this technology. At the Department of Radiation Oncology, University Hospital Zurich, MRI-simulations for RT planning using a dedicated scanner have been performed since 2023. The investigators have developed and implemented an MRI-only RT planning workflow followed by RT delivered at a CBCT-guided, conventional linac. The aim to expand the MRI-only workflow to online adaptive RT. This study will investigate the feasibility of MRI-guided, online adaptive SBRT for pelvic and para-aortic lymph node metastases using a dedicated MR simulator and treatment delivery using conventional CBCT-linac technology.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Intra-pelvic and para-aortic lymph node metastases from a histologically confirmed malignancy;
Indication for SBRT based on a multidisciplinary tumor board recommendation and / or clinical practice guideline;
Intra-pelvic and para-aortic lymph node metastases confirmed by imaging and amenable for SBRT

Exclusion criteria

Large body size that would not fit the MRI-simulator bore;
Contraindications for MRI including but not limited to

electronic devices such as pacemakers, defibrillators, deep brain stimulators, cochlear implants that are labeled as MR unsafe. Electronic devices labeled as MR safe or MR conditional are not a contraindication;
metallic foreign body in the eye or aneurysm clips in the brain;
severe claustrophobia;
hip prosthesis that are labeled as MR unsafe;
More than 5 pelvic lymph node metastasis
Previous radiation therapy directly overlapping with SBRT in this study and leading to exceeding tolerance of OARs;
History of Crohn's disease, ulcerative colitis

Treatment and study plan

Magnetic resonance Imaging-guided online adaptive radiotherapy

Radiation

On each day of treatment, a new MRI scan in the treatment position will be acquired using the dedicated MR simulator, co-registered with the original one. The original target and organ at risk (OAR) contours will be propagated to the new image set using rigid and deformable image registration. The contours will be adapted to changes detected with MRI of the day. The original SBRT treatment plan will be adapted to the changed and hence adapted anatomy of targets and OARs by plan optimization. Dose calculation will be performed on the newly generated synthetic CT (preferred) or, if there is a contra-indication for synthetic CT, on the original image.

Primary outcomes

Rate of successfully delivered fractions

Time frame: during treatment, 1-2 weeks

Feasibility is measured as a successful delivery of an MRI-adapted plan using CBCT image-guidance in another room in 90% of the SBRT fractions.

Secondary outcomes

Average improvement of coverage of planning target volume

Time frame: During treatment, 1-2 weeks

Dosimetric advantage is defined as >5% improvement in coverage of the planning target volume (PTV) or >5% better sparing of one of the organs at risk (bowel, sigma , rectum, bladder).
Adverse Events

Time frame: during SBRT, 3 months and 24 months of follow-up

Common Terminology Criteria for Adverse Events (CTCAE), version 5.0

Sponsors and collaborators

Lead sponsor

University of Zurich

Other

Registry information

Official study title

Magnetic Resonance Imaging-guided Online Adaptive Radiotherapy Using a Dedicated MR-simulator and a Cone Beam CT Based Treatment Delivery for Stereotactic Body Radiation Therapy of Pelvic Lymph Node Metastases (MACULA-Trial)

Acronym: MACULA

Important dates

Study start: 2025
Primary completion: 2026
Study completion: 2028
First posted: Jul 24, 2025
Registry last updated: May 11, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.