CT - dectectors

Biomedical Engineering System

Dedicated to:Sir Fahad Akbar Ali.

From:Muhammad Ovais Ur Rehman2011/BM/20

Fb: www.facebook.com/muhammad.ovais.56

PARTS OF CT:

GantryDASComputerStorage

DAS (data acquizition system)DETECTORS

CURRENT TO VOLTAGE CONVERTERS

PRE AMPLIFIER

INTEGRATOR

ADC

To computer world

DETECTORS:

1)Scintillation2)Gas filled.

1) Cyntillation:Early cyntillation detectors are array

contained cyntillation crystal & PMT assemblies.

Drawbacks:Cannot be packed very tightly together.

(Might be chance of image loss.)

PMT require separate power supply for each one.

(require more power,Area,cost,etc).

Problem Over Come:PMT’s were replaced by Photo cathode

assembly.

Advantage:

Smaller in sizeCheaper in cost.No need of separate supply.

CRYSTAL MATERIALS:

1) Sodium iodide (Na I).2)Bismuth Germinate (BGO).3)Cesium iodide (CI).4)Cadmium thungstate

(CdWO4).

2) Gas FILLED:It has the same Efficiency as Scintillation

crystal .

We have to do it Air lock.

* They are constructed with large metallic chambers,

With baffles space approximately 1mm.

* Each small chamber function as a separate radiation detector.

GASES:

I. XENON gas.II. KRYPTON gas.III. XENON KRYPTON gas.

Manufacturer: Toshiba Model: Aquilion

Thank you