man m-ecat (Fichiers spéciaux) - CTI ECAT 6/7 medical image format (MedCon)

NAME

m-ecat - CTI ECAT 6/7 medical image format (MedCon)

DESCRIPTION

This is a painful format. You should check the source code for more info. There is only read support for ECAT 7. Below you will find the specs for the ECAT 6 format. The ECAT 7 format differs a little in header definitions and there is only one matrix entry per volume, while for ECAT 6 files there is one matrix entry per plane. All ECAT 6 image data is written in one file with `.img' extension.

----------------------------------------------------------------------- Important Definitions -----------------------------------------------------------------------

typedef struct mat_main_header {
        char            original_file_name[20];
        Int16           sw_version;
        Int16           data_type;
        Int16           system_type;
        Int16           file_type;
        char            node_id[10];
        Int16           scan_start_day,
                        scan_start_month,
                        scan_start_year,
                        scan_start_hour,
                        scan_start_minute,
                        scan_start_second;
        char            isotope_code[8];
        float           isotope_halflife;
        char            radiopharmaceutical[32];
        float           gantry_tilt,
                        gantry_rotation,
                        bed_elevation;
        Int16           rot_source_speed,
                        wobble_speed,
                        transm_source_type;
        float           axial_fov,
                        transaxial_fov;
        Int16           transaxial_samp_mode,
                        coin_samp_mode,
                        axial_samp_mode;
        float           calibration_factor;
        Int16           calibration_units,
                        compression_code;
        char            study_name[12],
                        patient_id[16],
                        patient_name[32],
                        patient_sex,
                        patient_age[10],
                        patient_height[10],
                        patient_weight[10],
                        patient_dexterity,
                        physician_name[32],
                        operator_name[32],
                        study_description[32];
        Int16           acquisition_type,
                        bed_type,
                        septa_type;
        char            facility_name[20];
        Int16           num_planes,
                        num_frames,
                        num_gates,
                        num_bed_pos;
        float           init_bed_position,
                        bed_offset[15],
                        plane_separation;
        Int16           lwr_sctr_thres,
                        lwr_true_thres,
                        upr_true_thres;
        float           collimator;
        char            user_process_code[10];
        Int16           acquisition_mode;

} Main_header;

#define MH_64_SIZE 446

typedef struct mat_scan_subheader { Int16 data_type, dimension_1, dimension_2, smoothing, processing_code; float sample_distance, isotope_halflife; Int16 frame_duration_sec; Int32 gate_duration, r_wave_offset; float scale_factor; Int16 scan_min, scan_max; Int32 prompts, delayed, multiples, net_trues; float cor_singles[16], uncor_singles[16], tot_avg_cor, tot_avg_uncor; Int32 total_coin_rate, frame_start_time, frame_duration; float loss_correction_fctr; Int32 phy_planes[8];

} Scan_subheader;

#define SSH_64_SIZE 236

typedef struct mat_image_subheader { Int16 data_type, num_dimensions, dimension_1, dimension_2; float x_origin, y_origin, recon_scale, /* Image ZOOM from reconstruction */ quant_scale; /* Scale Factor */ Int16 image_min, image_max; float pixel_size, slice_width; Int32 frame_duration, frame_start_time; Int16 slice_location, recon_start_hour, recon_start_minute, recon_start_sec; Int32 gate_duration; Int16 filter_code; Int32 scan_matrix_num, norm_matrix_num, atten_cor_matrix_num; float image_rotation, plane_eff_corr_fctr, decay_corr_fctr, loss_corr_fctr, intrinsic_tilt ; Int16 processing_code, quant_units, recon_start_day, recon_start_month, recon_start_year; float ecat_calibration_fctr, well_counter_cal_fctr, filter_params[6]; char annotation[40];

} Image_subheader;

#define ISH_64_SIZE 172

typedef struct mat_norm_subheader { Int16 data_type, dimension_1, dimension_2; float scale_factor; Int16 norm_hour, norm_minute, norm_second, norm_day, norm_month, norm_year; float fov_source_width; float ecat_calib_factor;

} Norm_subheader;

#define NSH_64_SIZE 30

typedef struct mat_attn_subheader { Int16 data_type, attenuation_type, dimension_1, dimension_2; float scale_factor, x_origin, y_origin, x_radius, y_radius, tilt_angle, attenuation_coeff, sample_distance;

} Attn_subheader;

#define ASH_64_SIZE 40

-----------------------------------------------------------------------

What does the format support or not support:

===========================================================================
Item            Supported                             Not Supported
===========================================================================
Color Map     : grayscale                                   -
File Endian   : big                                       little
Pixeltypes    : VAX Int16 (write)  | All (read)             -
===========================================================================
Scaling factors  : quantify & calibrate factors/image  are supported
---------------------------------------------------------------------------
Dimensions/Image : different dimensions for each image are NOT supported
---------------------------------------------------------------------------
Pixeltypes/Image : different pixeltypes for each image are NOT supported
===========================================================================

NOTES

The MedCon program also supports the reading of sinogram, attenuation and normalization files for conversion purposes but it does not support writing those file types. In fact, they will be considered as reconstructed data!

The format supports more pixeltypes. The reason for our restriction of writing only the Int16 type was our ECAT software that only supports the Int16 type.

We consider three kinds of images (planes) in an ECAT file:

(1) plain pixel values [no unit] (ppv = ppv) - the planes/images are NOT normalized

(2) quantified values [counts/second/pixel] (qpv = ppv * quant_scale) - the planes/images are normalized

(3) calibrated values [uCi/ml] (cpv = qpv * calibr_fctr) - the planes/images are normalized

The float values in the header are stored as VAX format.

FILES

/usr/local/xmedcon/source/m-ecat64.h      The header file.
/usr/local/xmedcon/source/m-ecat64.c      The source file.
/usr/local/xmedcon/source/m-matrix64.h    CTI header file.
/usr/local/xmedcon/source/m-matrix64.c    CTI source file.

SEE ALSO

AUTHOR

(X)MedCon project was written by Erik Nolf (eNlf) for the PET-Centre at Ghent University (Belgium).

tab(=); lB l lB l. e-mail:=enlf-at-users.sourceforge.net=www:=http://xmedcon.sourceforge.net