Advancing Radiotherapy QA at Gómez Ulla with Delta4 Phantom+

Interview with Francisco Javier San Miguel Avedillo, Head of the Medical Physics Department at Hospital Central de la Defensa ‘Gómez Ulla’ in Madrid, Spain.

As a ScandiDos reference center, Gómez Ulla integrates advanced QA solutions into its radiotherapy practice. We spoke with Francisco about his team’s QA workflow, the role of Delta4 in their daily work, and what drives him as a medical physicist.

Can you tell us about your team and the technology you use?

We have a small but highly skilled team of five medical physicists and four technicians.

In our radiotherapy department, we treat about 80 patients per day using two Elekta Versa HD linear accelerators and a high-dose-rate brachytherapy unit. The department is involved in Radiotherapy, Nuclear Medicine, X Ray Diagnostic Imaging and Radiation Safety.

We are continuously investing in technology to enhance treatment quality. The Delta4 Phantom+ has long been a part of our QA process, ensuring accurate pre-treatment verification.

More recently, we acquired two new linear accelerators with advanced features, along with various quality control systems, including Delta4 HexaMotion and Delta4 Insight. We’ve also integrated end-to-end phantoms to analyze treatment precision and optimize our safety margins.

Why Delta4 Phantom+?

When selecting a pre-treatment dosimetry system, several key factors were crucial to us:

• Reliability
• Speed & efficiency
• High spatial resolution
• Minimal setup time

The Delta4 Phantom+ met all these demands. Another important consideration was having an independent dose calculation system, preferably with a Monte Carlo algorithm, such as the Delta4 Insight software.

What stands out about Delta4 patient QA solutions?

The measurement phantom Delta4 Phantom+ is fast, efficient, and wireless, which makes setup much easier. It also measures dose distribution in two orthogonal planes, providing a true 3D verification of the treatment plan.

The motion platform Delta4 HexaMotion system allows us to study the impact of patient movement, such as respiratory or random prostate motion, on dose delivery.

We have also recently started using Delta4 Insight, a secondary dose calculation software that adds an independent verification of the dose calculation algorithm and verifies that the calculations the TPS makes are accurate.

Has anything about Delta4 Phantom+ surprised you?

The ability to measure without the need for an angle sensor is truly innovative and makes the task much easier!

What does your patient-specific QA process look like?

Once a treatment plan is approved by the physician, we begin the pre-treatment QA process:

• Dose Calculation: Our radiotherapy technicians calculate the dose on the Delta4 system.
• Data Transfer: The treatment plan and calculated dose are exported in DICOM format and imported into the Delta4 software.
• Phantom Positioning: The phantom is precisely positioned using laser alignment marks.
• Measurement and Analysis: The treatment dose is measured, and the Delta4 software automatically compares the measured and calculated dose using a 2% global, 2 mm gamma analysis.
• Documentation: If all values fall within tolerance, a PDF report is generated, printed, and uploaded to the record-and-verify network for seamless documentation and traceability.

How long does it take to complete a QA measurement?

The pre-treatment QA measurements, which are performed solely with the Delta4 Phantom+, take just over 5 minutes per patient.

The setup is quick and straightforward, the measurement duration matches the treatment delivery time, and the analysis is automatic.

The pre-treatment QA measurements, which are performed solely with the Delta4 Phantom+, take just over 5 minutes per patient.

In some cases we take dual measurements, either to enhance resolution or to expand the measured field.

If we need to assess motion effects, we use HexaMotion. This requires a longer setup and analysis time but provides valuable insights into how motion impacts dose distribution.

What do you enjoy most about your work as a medical physicist?

What I enjoy most about my work is the ability to combine physics with clinical practice.

I love the challenge of being in constant development to improve treatments for patients with complex pathology. The most rewarding part is that, through research in physics, we can significantly improve the survival of cancer patients through treatments that are very complex, yet at the same time, very simple.

How does Gómez Ulla collaborate as a ScandiDos reference center?

As a ScandiDos reference center, we not only use Delta4 Phantom+, HexaMotion, and Delta4 Insight in our daily workflows but also share our experiences with other institutions.

This knowledge exchange helps improve radiotherapy QA standards across multiple clinics. One example is the annual user meeting we host together with the Spanish ScandiDos distributor, Fimecorp, which is consistently well-attended.

A warm thank you to Francisco Javier San Miguel Avedillo for sharing his experience and insights!

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