GREENWATER 2.0: Reducing Iodinated Contrast Agents in Hospital Wastewater (GREENWATER 2)

May 27, 2026 updated by: I.R.C.C.S Ospedale Galeazzi-Sant'Ambrogio

GREENWATER 2.0: Cutting Edge Solution for Reducing Iodinated Contrast Agents Via Post-Administration Collection Device

The goal of this observational study is to learn if using a dedicated urine collection device after CT scans can help reduce the amount of iodinated contrast agent released into hospital wastewater in adult outpatients undergoing contrast-enhanced CT scans.

The main questions it aims to answer are:

  • Does the dedicated urine collection device improve patient acceptance and compliance with post-contrast urine collection?
  • How much iodinated contrast agent can be recovered from urine collected after CT scans?

Participants will:

  • Have their planned CT scan with iodinated contrast agent as part of their regular medical care.
  • Wait in the radiology department for about 60 minutes after the contrast injection.
  • Use a dedicated urine collection device before leaving the hospital.
  • Answer short questions about their experience with the device.

This does not change the CT scan, the contrast agent used, or the standard clinical imaging procedure. The only additional procedure is the use of the dedicated urine collection device after the scan.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

GREENWATER 2.0 is a single-center, prospective observational study with an additional urine collection procedure. The study will be conducted in the diagnostic imaging department of IRCCS Ospedale Galeazzi - Sant'Ambrogio and will include adult outpatients undergoing clinically indicated contrast-enhanced CT scans with iodinated contrast agents.

Iodinated contrast agents are widely used in CT imaging to improve diagnostic accuracy. After intravenous administration, these agents are predominantly eliminated unchanged through urine. Because conventional wastewater treatment may not fully remove iodinated contrast agent residues, urine collection shortly after contrast administration may represent a practical strategy to reduce their release into hospital wastewater.

The study builds on the previous GREENWATER study, which showed high patient willingness to participate in a sustainability-focused urine collection protocol after contrast-enhanced imaging. In GREENWATER 2.0, a dedicated urine collection device will be installed in the radiology department to make the collection process more practical and integrated into the clinical workflow.

Participants will undergo their scheduled CT scan according to standard clinical practice. The indication for the CT scan, the choice of iodinated contrast agent, the contrast dose, and the imaging protocol will not be modified for research purposes. After contrast injection, participants will be asked to remain in the radiology department for about 60 minutes and then use the dedicated urine collection device before leaving the hospital.

The study will evaluate whether this workflow is acceptable and feasible for patients in routine radiology practice. It will also assess the potential recovery of iodinated contrast agent residues from the collected urine. Additional information will be collected on the contrast agent administered, the volume of urine collected, the time between CT examination and device use, and patient-reported experience with the device, including comfort, ease of use, cleanliness, privacy, odor, waiting time perception, and clarity of instructions.

The study is expected to provide evidence on the feasibility of using a dedicated urine collection device in a hospital radiology department as a sustainability measure to reduce the environmental impact of iodinated contrast agents. The planned sample size is 416 participants, with recruitment expected to last approximately 12 months. The total study duration is expected to be approximately 18 months, including recruitment, data analysis, and preparation of the final study report.

Study Type

Observational

Enrollment (Estimated)

416

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Adult outpatients aged 18 years or older undergoing clinically indicated contrast-enhanced CT scans with iodinated contrast agents at IRCCS Ospedale Galeazzi - Sant'Ambrogio. Participants will receive standard clinical care, with no modification to the CT protocol or contrast administration. The only study-specific procedure is the post-contrast use of a dedicated urine collection device after an approximately 60-minute waiting period.

Description

Inclusion Criteria:

Adult patients aged 18 years or older. Patients scheduled for a clinically indicated contrast-enhanced CT scan with iodinated contrast agent.

Patients able to provide written informed consent. Patients willing to wait approximately 60 minutes after contrast injection before using the dedicated urine collection device.

Exclusion Criteria:

Patients unable to use the dedicated urine collection device for urine collection.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Adult Outpatients Undergoing Contrast-Enhanced CT
Adult outpatients scheduled for clinically indicated contrast-enhanced CT scans with iodinated contrast agents. Participants will undergo their standard CT examination with no change to the imaging protocol or contrast administration. After contrast injection, they will be asked to wait approximately 60 minutes in the radiology department and then use a dedicated urine collection device before leaving the hospital.
Device: Dedicated Urine Collection Device (Toilet)
A dedicated urine collection device installed in the radiology department for use after contrast-enhanced CT scans. Participants will undergo their CT scan according to standard clinical practice, with no change to the imaging protocol, contrast agent selection, or contrast administration. After iodinated contrast injection, participants will be asked to wait approximately 60 minutes and then use the dedicated device before leaving the hospital. The collected urine will be used to assess the potential recovery of iodinated contrast agent residues and the feasibility of this workflow in routine radiology practice.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Patient Acceptance and Compliance With Post-Contrast Urine Collection
Time Frame: At the time of the CT examination, up to 60 minutes after contrast injection
Proportion of eligible participants who agree to participate in the study and complete the post-contrast urine collection procedure using the dedicated urine collection device after contrast-enhanced CT.
At the time of the CT examination, up to 60 minutes after contrast injection

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Potential Recovery of Iodinated Contrast Agent From Collected Urine
Time Frame: At the time of the CT examination, up to 60 minutes after contrast injection
Amount or proportion of iodinated contrast agent recovered from urine collected using the dedicated urine collection device after contrast-enhanced CT, based on the administered contrast agent and urine analysis.
At the time of the CT examination, up to 60 minutes after contrast injection

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

I.R.C.C.S Ospedale Galeazzi-Sant'Ambrogio

Collaborators

Bracco Imaging S.p.A.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 10, 2026

Primary Completion (Estimated)

September 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

May 27, 2026

First Submitted That Met QC Criteria

May 27, 2026

First Posted (Actual)

June 2, 2026

Study Record Updates

Last Update Posted (Actual)

June 2, 2026

Last Update Submitted That Met QC Criteria

May 27, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • GREENWATER 2.0

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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