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The Dosimetry Company

The use of ionizing radiation for diagnostic and therapeutic purposes is an integral part of today’s medicine. Since the discovery of X-rays by Wilhelm Röntgen in 1895, scientific and technological progress has led to better diagnostic testing and safer radiotherapy treatments.

As a pioneer in medical radiation measurement, PTW has always been – and will continue to be – at the forefront of advancing patient safety through innovation and cutting-edge measurement technology.

PTW - Our history of 100 Years

Making radiation safer - this is our mission that has driven us for 100 years now.
We invite you to dive with us into 100 years of PTW company history!

Our Company. Our Identity.

PTW is a global market leader for dosimetry solutions focusing on four markets – radiation therapy, diagnostic radiology, metrology and radiation monitoring. For almost a century, our innovations and technologies have contributed significantly to advance patient safety in modern radiation medicine. The precision of our measurement technology is legendary and has built PTW’s reputation as a quality and technology leader in medical radiation measurement.

From a backyard workshop to a global market leader

Our roots go back to 1922 when Dr. Wilhelm Hammer decided to market the first X-ray therapy dosemeter based on an electrostatic relay, a revolutionary new electromechanical component which he had invented three years earlier. He set out to establish his own company - Physikalisch-Technische Werkstätten. Hammer’s invention, which for the first time made it possible to accurately measure radiation dose on X-ray therapy units, marks an important milestone in making radiation treatments safer and laid the foundation for PTW’s success story.

In 1927, Hammer passed on the business to his former student. Under the pioneering leadership of Dr. Herbert Pychlau and his successors, PTW expanded into new markets and geographical areas and gradually grew from a six people backyard workshop to a worldwide operating company that continues to set standards in modern dosimetry.

A future-oriented, quality-driven family business

The entrepreneurial spirit, engineering excellence and strong commitment to quality through constant innovation of the early times are part of our culture and still guide our company to this very day.

Today, PTW is a key player in the dosimetry market, holding the No. 1 position in many countries and product categories. Supported by the largest sales and service network worldwide, PTW offers the most extensive portfolio of dosimetry technology in the industry – from detectors to water phantoms, from dosemeters and electrometers to intelligent solutions for quality assurance of complex clinical radiation equipment.

As a future-oriented family business, PTW is independent in its decisions and actions, aiming at organic growth and long-term partnerships with its many associates – customers, employees as well as business and research partners. More than 450 dedicated colleagues work at our headquarters in Freiburg, including two manufacturing sites, and at 12 international branch offices to deliver the best quality in technology and service to medical radiation experts in over 160 countries worldwide. Their commitment and passion has always been a key factor for our success.

Our promise to deliver first-class quality goes far beyond developing and manufacturing state-of-the-art technology in house. It is the essence of what drives us forward.

More than 12,000 calibrations per year

Quality starts with calibration. At its headquarters in Freiburg, PTW also operates one of the oldest and largest accredited dosimetry calibration laboratories in the field of ionizing radiation.

As a member of the IAEA / WHO/SSDL network, the PTW Calibration Lab provides calibrations directly traceable to national and international standards, thus ensuring that radiation instruments are always safe and compliant with current legislation.

Sharing knowledge, inspiring practice

As technology evolves and radiation treatments become more complex, the access to up-to-date knowledge in clinical dosimetry is vital. In 2014, PTW established THE DOSIMETRY SCHOOL to meet the need for basic and advanced dosimetry education.

True to its motto “Sharing knowledge, inspiring practice”, the Dosimetry School not only offers a great variety of training opportunities, but also provides a global platform where participants from all over the world are invited to share knowledge and experience, discuss topics of interest and engage in professional networking.

Our History. Our Heritage.

In 1919, Dr. Wilhelm Hammer, an associate physics professor at the Physics Institute of Freiburg University, invented the electrostatic relay which made it possible to precisely measure very small electrical charges.

Recognizing the importance of his invention for therapy X-ray applications, Hammer established a new company - Physikalisch-Technische Werkstätten. 

In 1922, he started producing the first ‘Hammer’ dosemeters based on his invention in his garden shed.

This is how the story of PTW began.

A History of Setting Standards in Dosimetry

Take a closer look at the milestones and inventions that shaped PTW’s history since 1922. Follow our timeline and learn how we became what we are today – The Dosimetry Company.


Pioneer Days

Invention of the ‘Electrostatic Relay”, a new revolutionary electromechanical component, by Dr. Wilhelm Hammer, associate physics professor, at the Physics Institute of Freiburg University. Hammer’s invention, which makes it possible to accurately measure radiation dose on X-ray therapy units, lays the foundation for the company’s success story.


To market the first dosemeter based on his invention, Hammer establishes his own company - Physikalisch-Technische Werkstätten. On 9 May 1922, the new company is incorporated. Its first registered address is Hammer’s private residence in Freiburg.

The Hammer Dosemeter

The ‘Hammer Dosemeter’ is the first X-ray therapy dosemeter based on an electrostatic relay, a technology that will build PTW’s reputation. Production starts from the garden shed at Hammer’s private residence.


A chance encounter shapes PTW’s future: Dr. Herbert Pychlau, a former PhD student of Hammer, meets Hammer on the street - and joins the company. Hammer is a full-blood scientist. He wants to resume his research at university and passes the business on to his former student. Under the pioneering leadership of Herbert Pychlau, PTW builds its reputation as a technology and quality leader for dosimetry equipment.


PTW needs more production space and moves into new rented premises located at Merzhauser Straße.

By the end of the 1920s, PTW has produced more than 30,000 electrostatic relays and sold more than 1,000 Hammer dosemeters.


The First Water Phantom

PTW launches the first commercial water phantom and water-proof ionization chambers. It marks the beginning of PTW’s market leadership in water phantom technology.


During wartime, the calibration laboratory, which has been in operation since the early times of the company, continues to provide calibration services for installed radiation instruments.


Technological Leadership

In the post-war era, PTW is part of the German Wirtschaftswunder (economic miracle). It grows steadily and initiates inventions that later become an industry standard.


The First Two-in-One Dosemeter

Introduction of DUPLEX, the first dosemeter worldwide that measures dose and dose rate. It marks a technology leap - from the electrostatic relay to the electron tube.


PTW makes a crucial investment: Supported by the Mayor of Freiburg, it purchases new premises of 7,044 m² and starts building. The new building at Lörracher Strasse 7 becomes the corporate headquarters of PTW.


The First DAP Meter

A breakthrough invention that sets the standard for an entire industry and underlines PTW’s reputation as a dosimetry expert: The legendary DIAMENTOR is the first dose area product (DAP) meter ever.


Growth and Expansion

Dr. Herbert Pychlau dies unexpectedly. He is succeeded by his son, Dr. Peter Pychlau, and Hans-Georg Löffler. Under their leadership, PTW develops into a full range supplier of dosimetry equipment for all major medical radiation applications.

The 1970s see a rapid succession of product developments based on new technologies. With the launch of one of the first dosemeters with field-effect transistors, DOSIMENTOR, and the first computer-controlled water phantom, MP2, PTW secures its leadership position and takes the next technology leap.


The PTW calibration laboratory is the first dosimetry calibration laboratory in the field of ionizing radiation to receive accreditation by PTB, Germany’s national institute of metrology.



Launch of the MP3 family of motorized 3D water phantoms with the largest variety of tank sizes in the industry. MP3 will become one of the most successful water phantom brands in the market and keep its position for years to come.



With the first microprocessor-controlled universal dosemeter that offers a 1fA measurement resolution, PTW sets a new technology standard for reference-class electrometers. The outstanding precision and reliability of the UNIDOS makes PTW an undisputed market leader for absolute dosimetry equipment.


PTW is growing steadily and expands portfolio and staff. It now employs more than 100 people. Dr. Edmund Schüle is appointed Managing Director and manages PTW jointly with Dr. Christian Pychlau. Under their leadership, PTW grows into one of the world’s leading dosimetry companies.


PTW expands globally. PTW-New York is the first branch office to open outside Germany. By 2012, PTW has established eight branch offices in key geographical areas – USA, Latin America, China, Asia Pacific, India, France, Iberia and UK.


Flat-Panel Ionization Chamber Arrays

Starting with the first liquid-filled linear array, L48, as early as 1996, PTW is the first company to develop high-resolution ionization chamber arrays to make dose verification and machine QC measurements more efficient. The 2D-Array seven29 and STARCHECK hit the market throughout the 2000s and become an immediate success. With OCTAVIUS 1000 SRS, the first liquid-filled 2D array for stereotactic applications enters the market three years later, initiating a new era in detector array development.


Our staff is growing rapidly. The PTW family now counts 200 dedicated employees in six international branch offices.



Launch of the first 4D patient QA system with a rotating, motorized phantom that allows measurements inside the entire phantom volume. Its new technology and modular design, which make it possible to exchange and upgrade detector arrays, makes OCTAVIUS 4D a highly successful product among users.


The First Synthetic Diamond Detector

Introduction of the first synthetic diamond detector, microDiamond. A breakthrough invention that confirms PTW’s leadership role in modern detector technology.


The PTW Dosimetry School starts off on 31 January 2014. Since then, it has held more than 70 courses in over 14 countries, welcoming more than 900 participants. 15 courses were held at 5 different Reference Sites.



With the launch of its cutting-edge 3D water phantom, Beamscan, which comes with a fully automated setup and wireless operation, our company sets a new benchmark in terms of technology, efficiency and ease of use.

PTW acquires FRATORIA, a highly specialized software developer, to expand its R&D capabilities.


Space for future growth: PTW expands its production capacities with a new production site in Umkirch, increasing the total production area to 7,900 m².


The next generation takes over: Dr. Tobias Schüle follows his father, Dr. Edmund Schüle, as Managing Director. He leads the company jointly with Dr. Christian Pychlau, the third generation of the owner family.


Investment for the future: With the acquisition of the two contiguous areas adjacent to PTW’s headquarters in Freiburg, the company doubles its premises to approx. 20,000 m². The staff increases to 300 people.


PTW acquires a share in phantom manufacturer QRM: The partnership brings together expertise in quality assurance for radiation therapy and diagnostic radiology.

Meanwhile, the PTW family counts 400 dedicated employees in 11 international branch offices. On March 1, 2022, PTW Netherlands changed its name to PTW Benelux and additionally took over the exclusive distribution rights for PTW products in Belgium and Luxembourg.

New Generation Electrometers

Nearly 100 years after PTW launched the first dosemeter, a new generation of electrometers is ready to set a global benchmark in terms of technology and usability: The new UNIDOS electrometers are the first generation to feature a 5-inch capacitive touchscreen and UNIDOS Tango is the first electrometer worldwide featuring Intelligent Detector Recognition (IDR), which automates detector management and identification.

UNIDOS Tango and UNIDOS Romeo Reference Class Electrometer

Change of Managing Director: Dr. Christian Pychlau retires after being a Managing Partner since 1996. Starting from February 2023, Bernd Allgaier takes over his position in the dual leadership of the dosimetry company and will lead PTW jointly with Dr. Tobias Schüle.

Stronger commitment to Africa: PTW opens the PTW Africa branch office in Cairo to strengthen its reach and responsiveness to customer demands in Africa. PTW Africa is a clear demonstration of our commitment to a growth market of the future and will act as a knowledge and service hub for the entire region.


Starting from January 2024, Oliver Ringleb joins the management team as the third Managing Director, with responsibility for the areas of Production, Supply Chain, and Digitalization.

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