In 1957 Herbert Pychlau had the idea of a new diagnostic measuring device determining the patient load during medical X-ray examinations. This measuring device was meant to show young radiologists working in teaching hospitals the patient dose consequences of radiological procedures also considering minimizing techniques like collimation or filtration adjustment. Herbert Pychlau invented a new measuring quantity based on the inverse square law, which he named the "Dose Area Product (DAP)". The DAP is the product of the multiplication of the entrance dose and the area of the irradiated field. Doubling the distance increases the radiation area by factor four, while the dose decreases simultaneously by factor four. Both effects cancel out each other and therefore the new unit [R*cm²] was ideal for educational measurements as it is independent of the focus patient distance.
DIAMENTOR - The Story of the Dose Area Product Meter
In 1959 PTW-Freiburg released the first DAP meter worldwide called DIAMENTOR. The measuring principle: An ionization chamber installed to the X-ray collimator determines the patient radiation load during X-ray examinations while the DIAMENTOR electronics measure and display the DAP value. The following years Herbert Pychlau and his son Peter struggled with a host of problems introducing the DIAMENTOR into routine clinical work. Starting with technical issues (non-transparency of the first original chamber) and continuing through user handling difficulties (chamber maintenance and problems in understanding the meaning of the new measuring quantity) up to difficulties with public authority acceptance.
In 1964 the study "Messung der Patientendosis in der Röntgendiagnostik" was published by E. Bunde and Peter Pychlau, showing the correlation between the DAP and the patient load. This work found such a great national and international recognition that a working group was founded with the aim to define a national German standard establishing legal rules on how to use DAP meters in X-ray diagnostic departments.
In 1987 the first German "X-Ray Directive" called "Röntgenverordnung" was published, having the ultimate objective to keep radiation levels in general and especially during high dose and high risk X-ray examinations such as fluoroscopy as low as possible. This was the breakthrough for the use of the DIAMENTOR.
In 1987 the first German "X-Ray Directive" called "Röntgenverordnung" was published, having the ultimate objective to keep radiation levels in general and especially during high dose and high risk X-ray examinations such as fluoroscopy as low as possible. This was the breakthrough for the use of the DIAMENTOR.
Another milestone came up when the FDA issued the final rule to amend the “Federal performance standard for diagnostic x-ray systems and their major components". FDA 21 CFR Part 1020 Federal Register became effective in June 2006 stating that fluoroscopic equipment manufactured on or after June 10, 2006 has to display the dose values during the examination.
Today, the DIAMENTOR is going stronger than ever before. It is a must in X-ray diagnostics worldwide, not only helping to reduce patient exposure, but also being an independent quality control tool, informing the operator about any deviation of the X-ray unit constancy. For more than six decades the measuring principle is still the same while the PTW DIAMENTOR product portfolio of course changed: PTW provides integrated, built-in, multi channel and combined dose and DAP DIAMENTOR solutions. Over the years PTW as pioneer of the DAP meter has delivered many thousands of reliable instruments to satisfied customers worldwide.
