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

Abstract

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 (CTDIvol) 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 CTDIvol 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.

Diagnostic Reference Levels based on clinical indications in computed tomography: a literature review

“…The DRL ci for fracture was the clinical indication with more references found (six out of eight). The DLP values ranged from 300 mGy.cm [ 18 ] to 640 mGy.cm [ 15 ]. One publication presents DRL ci for head CT both for males and females [ 16 ], however, with similar values.…”

“…The DRL ci for liver metastasis and kidney stone/colic were the clinical indications with more references found (6 out of 12). For liver metastasis, the DLP values ranged from 400 mGy.cm [ 15 , 19 ] to 1423 mGy.cm [ 27 ]. For kidney stone/colic, the DLP values ranged from 200 mGy.cm [ 33 ] to 460 mGy.cm [ 18 ].…”

“…The DRL ci for abscess/lymphadenopathy was the clinical indication with more references found (four out of five). The DLP values ranged from 650 mGy.cm [ 11 , 15 , 34 ] to 750 mGy.cm [ 18 ].…”

“…The DRL ci for tumour and oncologic follow-up were the clinical indications with more references found (two out of three). For tumour, the DLP values ranged from 870 mGy.cm [ 15 ] to 950 mGy.cm [ 35 ]. For oncologic follow-up, the DLP values ranged from 605 mGy.cm [ 36 ] to 970 mGy.cm [ 34 ].…”

Radiation dose monitoring in computed tomography: Status, options and limitations

“…Finally, it should be noted than special low dose protocols for some clinical indication, e.g. renal stone CT [74,75] and pulmonary nodule follow-up CT, should be distinguished from other protocols that share the same anatomic scan region, otherwise they will constantly produce low dose outliers.…”