autods_pet.imaging.normalization#

SUV normalization for PET images.

Converts raw PET activity concentration (Bq/mL) to SUV body-weight (SUVbw) using patient weight and injected dose. Includes helpers for parsing DICOM timing metadata and computing decay-corrected dose.

autods_pet.imaging.normalization.parse_dicom_time(tstr)[source]#

Parse a DICOM TM string into a datetime.time.

Handles missing leading zeros, fractional seconds, and hours >= 24 (wrapped modulo 24).

Parameters:

tstr (str) – DICOM TM-format string (e.g. "143012.123456").

Return type:

time

Raises:

ValueError – If tstr is empty.

Examples

>>> from autods_pet.imaging.normalization import parse_dicom_time
>>> parse_dicom_time("143012.000000")
datetime.time(14, 30, 12)
>>> parse_dicom_time("090000")
datetime.time(9, 0)
autods_pet.imaging.normalization.parse_dicom_date(dstr)[source]#

Parse a DICOM DA string (YYYYMMDD) into a datetime.date.

Parameters:

dstr (str) – DICOM DA-format string (e.g. "20230415").

Return type:

date

Raises:

ValueError – If dstr is too short or contains invalid month/day.

Examples

>>> from autods_pet.imaging.normalization import parse_dicom_date
>>> parse_dicom_date("20230415")
datetime.date(2023, 4, 15)
autods_pet.imaging.normalization.seconds_between(injection, acquisition, max_uptake_hours=6.0)[source]#

Seconds elapsed from injection to acquisition, handling midnight wrap.

If the elapsed time is slightly negative (0 to -max_uptake_hours), assumes the acquisition crossed midnight and adds 24 h. If more negative than -max_uptake_hours, still corrects but logs a warning.

Parameters:

  • injection (datetime) – Radiopharmaceutical injection time.

  • acquisition (datetime) – PET acquisition time.

  • max_uptake_hours (float (default: 6.0)) – Maximum expected injection-to-scan interval in hours. Negative elapsed times within this window are assumed to be midnight wraparounds. The default of 6 h is appropriate for standard 18F-FDG protocols (typical uptake ~60 min). Increase for tracers with longer uptake periods (e.g. 68Ga-DOTATATE).

Returns:

Elapsed seconds (always >= 0 after midnight correction).

Return type:

float

Examples

>>> from datetime import datetime
>>> from autods_pet.imaging.normalization import seconds_between
>>> seconds_between(datetime(2023, 1, 1, 9, 0), datetime(2023, 1, 1, 10, 0))
3600.0
autods_pet.imaging.normalization.decay_dose(dose_bq, half_life_s, elapsed_s)[source]#

Apply radioactive decay: dose * exp(-lambda * t).

Parameters:

  • dose_bq (float) – Initial dose in Bq.

  • half_life_s (float) – Radionuclide half-life in seconds.

  • elapsed_s (float) – Time elapsed since injection in seconds.

Returns:

Decayed dose in Bq.

Return type:

float

Examples

>>> from autods_pet.imaging.normalization import decay_dose
>>> round(decay_dose(370e6, 6586.2, 3600), 1)
253314180.2
autods_pet.imaging.normalization.effective_dose(total_dose_bq, half_life_s, elapsed_s, decay_correction)[source]#

Determine the effective reference dose depending on the DICOM DecayCorrection tag.

Parameters:

  • total_dose_bq (float) – Injected radionuclide dose in Bq.

  • half_life_s (float) – Radionuclide half-life in seconds.

  • elapsed_s (float) – Seconds between injection and acquisition.

  • decay_correction (str) – DICOM DecayCorrection value (e.g. "NONE", "START", "ADMIN").

Returns:

Dose in Bq to use as the SUV denominator.

Return type:

float

autods_pet.imaging.normalization.compute_suvbw(pet_bqml, weight_kg, dose_bq)[source]#

Convert a PET image from Bq/mL to SUV body-weight.

Parameters:

  • pet_bqml (Image) – PET image in Bq/mL units.

  • weight_kg (float) – Patient body weight in kg.

  • dose_bq (float) – Effective injected dose in Bq (after decay correction if needed).

Returns:

PET image in SUVbw units (float64).

Return type:

Image