.svg){kind=logo}
.jpg)
Powering X-ray Detectors - the Role of High and Low Voltage Power Supplies
Posted March 17, 2025 by Dr. Simone Baer-Lang
Blog Summary
1. Critical Role of Detectors: Detectors in modern digital X-ray devices are essential for converting incoming X-rays into electrical signals, which are then processed to generate clinical images used for diagnosis and treatment in medical settings. These detectors are also used in various industrial applications.
2. Conversion Methods: There are two primary methods for converting X-rays into electrical signals: indirect and direct. Indirect detectors convert X-ray photons into visible light before converting them into electrical signals, while direct detectors convert X-ray photons directly into electrical charges.
3. Importance of Power Supplies: The performance of power supplies driving these detectors is crucial for image quality. High voltage supply considerations, such as noise, ripple, and thermal stability, significantly impact the final signal or image quality. Efficient power conversion improves reliability and reduces system temperatures, enhancing overall performance.
1. Critical Role of Detectors: Detectors in modern digital X-ray devices are essential for converting incoming X-rays into electrical signals, which are then processed to generate clinical images used for diagnosis and treatment in medical settings. These detectors are also used in various industrial applications.
2. Conversion Methods: There are two primary methods for converting X-rays into electrical signals: indirect and direct. Indirect detectors convert X-ray photons into visible light before converting them into electrical signals, while direct detectors convert X-ray photons directly into electrical charges.
3. Importance of Power Supplies: The performance of power supplies driving these detectors is crucial for image quality. High voltage supply considerations, such as noise, ripple, and thermal stability, significantly impact the final signal or image quality. Efficient power conversion improves reliability and reduces system temperatures, enhancing overall performance.
Detectors in modern digital X-ray devices are highly critical components that convert incoming X-rays into electrical signals. In medical X-ray, these signals are then processed by computer hardware and software to generate relevant images.
Medical devices utilizing X-rays include digital Bucky systems, catheterization laboratories, surgical C-arms with flat panels, and digital mammography units. Clinical images generated by these X-ray devices are used by radiologists to diagnose and potentially treat a specific condition inside the body. In addition, X-ray technology is used in several industrial inspection applications, ranging from semiconductor manufacturing to food production and oil and gas leakage detection. In many cases, the performance of the power supplies used to drive these detectors is highly critical to the signal or image quality of the X-ray systems.
Converting X-rays to electrical signals
The “golden standard” today is still solid-state detectors using semiconductor materials. There are two different methods (and two different types of hardware) used to convert X-rays into electrical signals – indirect and direct.
Indirect detectors require an extra step, i.e., converting X-ray photons into visible light in a scintillator layer. The light is then captured by an array of photodiodes that are light absorbing (usually Photomultiplier Tubes, PMT, which have an integrated high voltage (HV) DC-DC – these integrated products are beyond the focus of this blog). These photodiodes will turn the light into carriers of electrical charge (electron-hole pairs). The electrical signals from the photodiodes are proportional to the amount of light. These electrical signals are then amplified and encoded by additional electronics.
Indirect flat panel detectors for standard medical X-rays usually run at 18 VDC. Manufacturers of portable flat panel detectors face the challenge of fitting additional electronics into the frame, which must be both highly compact and thermally stable.
Direct detectors use photoconductive material to convert X-ray photons directly into an electrical charge (electron hole pairs) via the photoelectric effect. With a bias voltage, the electrodes quickly draw the charge, and the generated current is directly proportional to the X-ray intensity. The current values are then interpreted by the signal and data processing electronics. The bias voltage is usually depending on the detector material and thickness. The HV DC-DC product generating the bias voltage, which often uses a 12 or a 24 VDC input, must produce very low ripple and noise.
High voltage supply considerations
In any imaging system, the noise and ripple on the output of the high voltage supply are critical as they compromise the image quality. Any ripple present at the point of detection will degrade signal integrity and then become amplified before being analyzed and ultimately displayed. To achieve the best possible image quality, defining and managing this power source parameter is crucial to successfully implementing the system.
The size of the equipment is also important as there is growing pressure to reduce size, especially in portable systems. Functions requiring higher power in a physically smaller volume is a primary challenge. Efficiency performance of power conversion is essential to address this challenge. Higher efficiency of power conversion produces lower dissipated power from the power converters and requires less volume.
Additionally, if there is lower dissipated power in a system, its thermal stability is inherently improved. This ensures that the equipment maintains its performance level regardless of the duration of its operation. Thermal drift and change in power supply noise and ripple characteristics can affect image resolution and quality if not carefully managed.
Benefits of highly efficient power conversion
Highly efficient power conversion can improve the reliability of the end system. The resulting reduction in power dissipation leads to lower system temperatures and increased reliability levels.
Regardless of the detector technology used, the requirements from a manufacturer and end-user perspective are the same. A cost-effective solution that is as sensitive as possible and offers the highest possible accuracy and reliability is desirable. This allows for the best possible resolution while – especially in medical Imaging adhering to the as low as reasonably achievable (ALARA) dose principle while maintaining a high image quality.
Conclusion
No matter the functionality required for the additional electronics in x-ray detector applications, the power supplies are still essential components. Their noise and ripple, thermal dissipation and stability during examinations, and input and output operating ranges are critical. Any compromise in these areas may have a direct impact on the final signal or image quality.
In addition, physically small, highly efficient and reliable power converters that have good thermal stability enable X-ray systems suppliers to target a broad range of highly reliable and precise stationery and portable applications.
Figure 2
With the broadest portfolio of AC-DCs (internal and external), low voltage and high voltage DC-DC standard and modified products and platforms, coupled with extensive applications and compliance experience, Advanced Energy offers systems designers an unrivalled range of proven power solutions for any detector power supply design.
For more information about Advanced Energy’s detector power supplies, visit Medical Imaging Power Supplies | Advanced Energy.
References:
1. Radiation Detection Systems, Sensor materials, Systems, Technology and Characterization Measurements (Jan S. Iwanczyk; Krzysztof Iniewski, doi:10.1201/9781003147633
2. Introduction to Medical Imaging - Physics, Engineering and Clinical Applications Nadine Barrie Smith Pennsylvania State University & Andrew Webb Leiden University Medical Center 9780521190657_frontmatter.pdf
3. Kump, K; Grantors, P; Pla, F; Gobert, P (December 1998). "Digital X-ray detector technology". RBM-News. 20 (9): 221–226. doi:10.1016/S0222-0776(99)80006-6.
4. Kotter, E.; Langer, M. (19 March 2002). "Digital radiography with large-area flat-panel detectors". European Radiology. 12 (10): 2562–2570. doi:10.1007/s00330-002-1350-1. PMID 12271399. S2CID 16677678
5. Direct vs. Indirect Conversion Archived January 2, 2010, at the Wayback Machine
6. Digital Detectors for Industrial Applications, Nityanand Gopalika (Digital Detectors for Industrial Applications-Nityanand Gopalika | PPT)
7. https://www.radiation-dosimetry.org/what-is-alara-definition/
1. Radiation Detection Systems, Sensor materials, Systems, Technology and Characterization Measurements (Jan S. Iwanczyk; Krzysztof Iniewski, doi:10.1201/9781003147633
2. Introduction to Medical Imaging - Physics, Engineering and Clinical Applications Nadine Barrie Smith Pennsylvania State University & Andrew Webb Leiden University Medical Center 9780521190657_frontmatter.pdf
3. Kump, K; Grantors, P; Pla, F; Gobert, P (December 1998). "Digital X-ray detector technology". RBM-News. 20 (9): 221–226. doi:10.1016/S0222-0776(99)80006-6.
4. Kotter, E.; Langer, M. (19 March 2002). "Digital radiography with large-area flat-panel detectors". European Radiology. 12 (10): 2562–2570. doi:10.1007/s00330-002-1350-1. PMID 12271399. S2CID 16677678
5. Direct vs. Indirect Conversion Archived January 2, 2010, at the Wayback Machine
6. Digital Detectors for Industrial Applications, Nityanand Gopalika (Digital Detectors for Industrial Applications-Nityanand Gopalika | PPT)
7. https://www.radiation-dosimetry.org/what-is-alara-definition/
Dr. Simone Baer-Lang
Advanced Energy
Simone Baer-Lang is a Senior Strategic Marketing Manager, Medical Power Products at Advanced Energy dedicated for medical Imaging. She joined Advanced Energy in 2023 and has previously held a number of senior roles in product& BusinessLine management, product & technical marketing, and business development in a number of leading medical technology and Imaging companies. Simone holds a Higher Diploma and PhD in Physics from RWTH Aachen University, during those times she was doing research at DESY as well at the Forschungszentrum Jülich.
More posts by Dr. Simone Baer-Lang