Patient dose evaluation in computed tomography: A French national study based on clinical indications

Purpose: A national survey was performed to assess patient dose indicators based on clinical indication and on patient morphology for most common adult computed tomography (CT) examinations in France.

Methods: Seventeen groups of clinical indications (GCIs) for diagnostic CT in adult patients were considered based on their frequency and on image quality requirements. Data was collected for 15-30 consecutive examinations performed between 2015 and 2017, per CT scanner and GCI. Distributions of total examination Dose-Length Product (DLP) and Volume CT Dose Index (CTDI_vol) were assessed for each GCI as a function of patient gender or patient Body Mass Index (BMI) for head/neck and trunk examinations, respectively.

Results: 6610 examinations were analysed. Median total exam DLP values were higher for men compared to women patients for head and neck examinations: difference ranged from 6% for ear trauma indication (577 vs 543 mGy·cm, p = 0.01) to 35% for brain tumour GCI (1472 vs 1093 mGy·cm, p < 0.01). For trunk examinations, total exam DLP increased consistently with patient's BMI. For normal-BMI patients, median CTDI_vol and DLP differed significantly between different GCIs for single-phase CT of the chest (3 mGy and 112 mGy·cm, respectively, for chronic obstructive pulmonary disease group vs 5.8 mGy and 207 mGy·cm for pulmonary embolism group, p < 0.05) and of the abdomen-pelvis (5.6 mGy and 284 mGy·cm, respectively, in renal colic group vs 9.5 mGy and 463 mGy·cm in occlusive syndrome group, p < 0.05).

Conclusion: This study provides morphological- and clinical-based patient dose indicators in CT as a practical tool for clinical practices optimisation.