The Role of Silicon Radiation Sensors In Medical Imaging - - PowerPoint PPT Presentation

The Role of Silicon Radiation Sensors In Medical Imaging Instrumentation.

Presented by P . Weilhammer

At HSTD8 in The Special Session In Honour Of Prof. Takashi Ohsugi

On the occasion of his retirement

1 HSTD8 5. Dec to 8. Dec 2011 Taipei

The contributions to the field of Si detector instrumentation of

• Prof. Ohsugi are discussed for many applications in this dedicated

session. His contributions over more than 3 decades in this field are

• immense. He has been one of the protagonists in using Si detectors

in tracking applications, at colliders, in fixed target physics and in space physics experiments. Out of his many hundred published papers a big number are devoted to silicon tracking detector development. His collaboration with industrial partners, in particular with Hamamatsu company, have resulted in many technical and design innovations, leading to fast progress in this field. I believe my task here is to discuss shortly in more general terms the role of silicon radiation sensors in Medical Imaging Instrumentation. The details are in the dedicated sessions.

2 HSTD8 5. Dec to 8. Dec 2011 Taipei

OUTLINE OF TALK

• 1. Introduction
• 2. Short Overview of present Medical Imaging

Methods and Detector T echnologies

• 3. A Couple of Examples of Silicon Detectors in

Medical Imaging Applications 3.Conclusion

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Medical Imaging in the 21st Century: “Multi Modality” The Famous Picture

While photographic emulsion was for a very long time without competition, important innovations in medical imaging were introduced over the last 50 to 60 years: Present Prevailing Imaging Methods :

• Anger Camera for SPECT
• First attempts on PET with Proportional Wire Chambers (1974)
• PET Scanners with High Z Scintillators and PM Readout using

Anger Logic ……..

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• MRI
• Attempts on Electronic Collimation in SPECT using Compton

Scattering of the Gamma Ray with Silicon or high Z semiconductor detectors Detectors

• XRAY
• CT with Silicon Photo Diode arrays in Current Mode
• XRAY
• CT with Silicon Photo Diode arrays in Counting Mode
• Ultrasound Scanners
• Etc……

With the exception of X-Ray CT where Silicon Photo Diodes Play a dominant role, Silicon Radiation Sensors are not very strongly represented in this field so far, at least what concerns industrialised products already in clinical environment. The dominant detector technologies clinically applied are:

• Scintillators
• PM

Tubes

• Maybe soon High Z semiconductors in Digital X-Ray CT
• SiPM Arrays (maybe a strong contender in the future)
• And more…….

7 HSTD8 5. Dec to 8. Dec 2011 Taipei

Position sensitive Si detectors in Medical Imaging Applications are still mostly in the development phase:

Just a few examples here

• Low Dose digital Mammography Scanner from SECTRA (single sided

strip detectors “edge on” and VLSI Front-end) See www.sectra.com Very promising for Screening in Mammography. Pruduct on the market since a number of years in several european countries.

• In this context I like to mention the very interesting proposal and

prototyping for another „edge on‟ configuration by S. Yoshida and Takashi Ohsugi using silicon strip detectors and tungsten plate

• ollimators:

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T

• p view of the imaging device.

The strips are parallel to each other in this figure but they have to be radial to detect X-rays from the point source. The device proposed by Prof. Ohsugi

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PET “Magnifying Glass”:

• Augment conventional

Scintillator PET ring with high resolution Insert made highly segmented silicon detectors.

• Very high resolution

possible in small FOV or close to detector (MADEIRA Project) A test set-up in Michigan for a lense with Si pads ( CIMA Collaboration)

HSTD8 5. Dec to 8. Dec 2011 Taipei 11

Axial PET Project

Readout of long LYSO scintillators (rods), aarranged axially and wavelength Shifter strips readout with SiPM (Hamamatsu MPPC.)

Orthogonal layers of LYSO crystals and Wave length shifting strips

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Typical results from tests with phantoms for these technologies shown so far

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Conclusions Reortss on more recent developments in Medical Application of silicon detectors will be presented during dedicated sessions in this symposium. Silicon radiation detectors are a fascinating field to work in.

• Prof. Ohsugi has contributed very importantly to this field in the

last decades and I am sure so that he will continue in this research field for a long time. The only difference will be that now he can ( hopefully) fully enjoy research and may be have less administrative duties. I wish Prof. Ohsugi much pleasure in the coming years. And I am sure I will certainly have the pleasure to meet him at the HSTD9 again.