Development of a silicon detector for photon counting

Development of a silicon detector for photon counting to be used in dual energy radiography in the range 18 -40 Ke. V § § Digital Mammography X ray tests Phantoms spectra Bilateral Project (ICM-tube X-ray)

Digital Mammography Vantages: • • • Better resolution Image manipulation Image Inversion Identification of other tissues Reduction of time in studies (half)

Silicon strip detector

Characteristics of SD • • • Position identification Energy 8 -30 Ke. V Spatial resolution 50 -100 um Fast electronics Low noise Low dose

Key system issues Fully parallel signal processing for all channels. Only binary (yes/no) information is extracted from each strip. Data from each channel must be stored in a local buffer for the whole measurement period. Silicon strip detector 64 PC computer bond wires

First prototype (1 x. RX 64) 0. 6 1. 0 cm 2 detector RX 64

Detector Tests • Calibration through an internal pulse to obtain gain and noise estimation of the system • Calibration through radiactive sources to obtain gain, noise and the absolute energy scale • Detector test using a X ray tube at CINVESTAV and a mammograph at Hospital Juárez • Obtain spectra with phantoms made in laboratory and an official phantom (ACR).

Calibration with radiation sources

Gain of 64 channels

Hospital Juárez-México Fis. Enrique Gaona (UAM-Xochimilco)

Scanning system – 2 D image Advantages compare to 2 D-systems: -reduced scatter background, -small number of the electronics channel. scanning slit

Activities in Mexico 2004 - Caracterization and tests in hospital by A. Leyva (posdoc ALFA). - Simulation of the system by a portuguese student (ALFA). - Test with ACR phantom by Roxana de la Mora (Bil. Proj. Cuba)

Phantom 1 (First tests) Colimator: 250 um Steps: 2 Time: 3600 s/step Cd-109 (22, 24 ke. V)

Semiconductor diode Image Colimador: 1 mm Pasos: 16 Tiempo: 600 s/paso Cd-109 (22, 24 ke. V)

Internal image LED Collimator: 1 mm Steps: 26 Time: 3600 s/step Cd-109 (22, 24 ke. V)

Structures Images with Cd-109 Collimator: 0. 5 mm Steps: 26 Time: 2400 s/step Cd-109 (22, 24 ke. V)

ACR Phantom The ACR phantom has structures that simulate microcalcifications of several sizes.

Internal details

BEDE X ray Tube Anode: Cu, window: Be ICM Project

Spectrum (64 strips) phantom 1 X ray tube

Mass profile (13) X ray tube mass 1 mm

Characteristics of mammograph in Hospital Juárez • • • Elscint, made in Israel Model MAM-CH 225 X ray tube model : XRHAVA Range: 22 -35 k. V Automatic adjustment of current Anodo-filter: Mo/Mo

Detail 12 and phantom 1 First results mass 2 mm Phantom 1 Time: 0. 8 s, 28 k. V, 90 m. As

International Collaboration

Publication

Biological Tissue (uterus) Analysis in progress…

Activities-Ricardo • • • 1(*)- Estudio de: a) Interacción de las radiaciones con la materia. b) Detección de las radiaciones ionizantes. d) Detectores semiconductores de silicio 2 - Calibración 2 chips RX 64. a) Determinación de la linealidad de los contadores. • b) Determinar Ampl DAC y Shaper DAC para el sistema. • c) Medición de la ganancia, offset y el ruido.

Activities… • 3 - Calibración energética del sistema de detección empleando fuentes patrones radioactivas. • 4 - Obtención de imágenes de objetos en el laboratorio • 5 - Simulacion del sistema con Geant

Activities done so far • 1 - Study of radiation interaction with matter (silicon) (*) • 2 - Study simulation programs (Litrani, Geant) (*) • 3 - Measurement of gain, noise and offset through calibration pulse and radiation sources. (see report) • 4 - Programs to obtain mean and sigma of data (developed in C) (*) * Should be in the report

Future activities… • Most of the measurement done sofar with edge-on configuration • Poisson test. • Biológical tissues measurementwith both front and edge on configutations. • Measurements with X ray tube and Mammograph.