The Delta4 Phantom+ for MR-linacs

The Delta4 Phantom+ MR is an innovative device for addressing pre-treatment quality assurance (QA) for highly modulated radiotherapy treatment plans in MR-linacs.

It is the ONLY system that measures the dose distribution in the isocentric region and not simply in one single flat or wrapped plane.

The patented geometric, dual orthogonal detector planes and the nature of the detectors make the Delta4 Phantom+ MR a unique quality assurance system.

MR-compliant for field strengths up to 1.5T

Fulfills the requirements in TG-218


What our customers say

The Delta4 Phantom+ MR is quick and easy to use and gives us confidence that our treatments are delivered just as they are intended.

Wilfred de Vries Clinical Physicist Engineer, UMC Utrecht

After good results of a number of tests, we decided to expand our existing Delta4 Phantom+ portfolio with the MR-compatible Delta4 Phantom+ MR.

Ulf Isacsson Chief Physicist, Uppsala University Hospital

We are very much looking forward to using the MR-compatible Delta4 Phantom+ at our Viewray MRIdian Linac as well as at our Elekta and Tomotherapy Linacs to further advance and streamline our patient QA.

Sebastian Klüter, PhD Medical Physicist, Department of Radiation Oncology, Heidelberg University Hospital

Delta4 software

Streamline your workflow

Integrated software

Keep up an efficient clinical workflow, thanks to well-integrated software. TPS plans can be easily imported together with TPS doses and structures.

Intuitive interface

Easily navigate between patients, measurements, and analysis. All the information you need is just a click away. The QA analysis is performed automatically as soon as the dose has been delivered, instantly indicating pass or fail.

Delta4 software

Instant and accurate analysis

Instant results

Your QA results, including dose deviation, distance to agreement (DTA), and gamma index, become available instantly—no further processing required. Easily customize QA reports to meet your specific needs.

Powerful analysis

The unique 4D measurements yield the data needed to analyze the delivered dose for fraction, beam arc, or control point. The delivered 4D dose can also be analyzed in the patient’s anatomy. The Delta4DVH suite of software modules provide unique analysis tools for finding the clinical significance of a deviation.

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Let us show you the full potential of Delta4 Phantom+ MR

Features and Benefits

Delta4 Phantom+ MR

Next-generation technology that works for your benefit

MR compatible

  • Up to 1.5T MRI
  • Compatible with Elekta Unity
  • Compatible with Viewray MRIdian

Intuitive software

  • Easy to use
  • Fully automated
  • Instant results in one place
  • Powerful analytic tools
  • Clear and modifiable reporting

Fast and easy calibration

  • Only absolute dose calibration needed
  • Fast absolute dose calibration in phantom
  • Optional independent check of absolute point dose with ionization chamber

Highest accuracy

  • Isocentric measurements in two orthogonal detector planes
  • 1069 p-type silicon diodes
  • Resolution 5 mm at isocenter, can be increased to 2.5 mm by merging
  • Measures where it matters

Superior detectors

  • Longterm stability
  • No re-calibration of relative sensitivity
  • Isotropic response
  • FFF compatible

Quick and easy setup

  • Setup and alignment done within seconds
  • Trolley eliminates all lifting
  • Trolley available for all types of treatment tables
  • Roll-and-store

Delta4 Software

Instant Results

Instant display of dose deviation, distance to agreement, gamma pass rate, and plan pass/fail status.

Wide range of analysis tools including profile display, isodoses, structure overlaying, continuous dose display, and dose volume histograms.

Possibility to calculate continuous dose distributions within the phantom.

Watch Webinars On-Demand

Patient QA for daily adaptive RT with an Elekta Unity MR Linac

Dr. Tilly from the Uppsala University Hospital provides an in-depth picture of the daily workflow when working in a magnetic field, including challenges encountered with plan adaptation. Dr. Tilly also explains how Patient QA is carried out in this environment.

Delta4 Phantom+ MR: Development, Acceptance and First Clinical Results

Wilfred de Vries, UMC Utrecht, reviews the following:

  • Development of a new generation Delta4 Phantom+
  • Challenges for QA in MRI-Linac
  • Acceptance results for Delta4 Phantom+ MR
  • First clinical results with Delta4 Phantom+ MR


Delta4 Phantom+ MR

Cylinder Phantom

Material PMMA, optional Plastic Water DT
Diameter 22 cm
Length / Total Length / Total Weight 40 cm / 71 cm / 25 kg
Control Unit Total Length / Total Weight 17 cm / 3 kg
Ion chamber insert in cylinder Inserts for common cylindrical ion chambers available


Type p-Si
Total number 1069
Layout Distributed on coronal and sagittal plane
Max field size 20 x 38 cm2 (when merging two consecutive measurements, otherwise 20 x 20 cm2)

Distance between detectors

Central area (6 x 6cm2) 5 mm (or 2.5 mm in longitudinal direction with merging of two consecutive measurements)
Outer area 10 mm
Size (radial x axial) 1 x 0.05mm3= 0,00004 cm3
Detector stability (6MV beam) Better than 0.1% per kGy, typically 0.04%/kGy


Modalities Photon beams, with and without flattening filter
Treatment plan import Any treatment planning system that can export DICOM RT plan, RT Dose, and RT Structure

MR compatibility

Fully compatible with all MR-linacs, no Faraday Cage issues

Power and communication

Ethernet connector (RJ-45) for communication
Power adaptor is included
Cables between remote unit and measurement phantom


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