(2026) Limantoro | Ultra-low dose pediatric chest PCCT approaching chest radiograph doses

Daniel Stromer

In this feasibility study, an ultra-low-dose pediatric chest PCCT protocol was optimized to Sn100 kVp, 2 mAs, pitch 1.5, achieving a phantom effective dose of 14 µSv. In clinical use, the median total effective dose was 11.6 µSv, close to the 8.2 µSv median dose of a single chest radiograph.

The protocol was applied in 24 examinations in 20 children, median age 10 years, and every examination provided sufficient confidence to answer the immediate clinical question. Image quality was strongest for focal abnormalities, known-lesion follow-up, congenital diaphragmatic hernia follow-up, and assessment of ILD progression.

The trade-off is task specificity: readers were less confident when using this ultra-low-dose protocol to rule out previously unknown ILD or bronchiectasis. The authors therefore position it as a targeted follow-up tool rather than a replacement for standard-dose chest CT when subtle diffuse lung disease must be excluded.

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Figure 2. CT scans during follow-up of a patient known with a coiled pulmonary AV malformation in the left upper lobe (red arrow). Axial (a) and coronal (b) images obtained on energy-integrating-detector CT (with intravenous contrast) when the patient was 9 years old (CTDI 3.43 mGy, SSDE 6 mGy, WED 20.5 cm). Axial (c) and coronal (d) images obtained on PCCT using ULDCT protocol (without intravenous contrast) when the patient was 13 years old (CTDI 0.01 mGy, SSDE 0.02 mGy, WED 22.5 cm).

Protocol

Detail	Value
Scanner	NAEOTOM Alpha
Scan area	Pediatric chest
Acquisition mode	Ultra-low-dose PCCT
Contrast	Noncontrast
Tube voltage [kVp]	Sn100
Tube current-exposure product [mAs]	2
Pitch	1.5
Rotation time [s]	0.25
Detector z-coverage	144 × 0.4 mm
Focal spot [mm]	0.8 × 1.2
FOV [mm]	350
Matrix	512 × 512
Pixel size [mm]	0.68
Reconstruction energy	73-keV VMI
Lung kernel	Bl56
Soft-tissue kernel	Br40
Iterative reconstruction	QIR 4
Lung slice thickness [mm]	1
Soft-tissue slice thickness [mm]	3
Clinical CTDIvol [mGy]	~0.01
Clinical SSDE [mGy]	0.019 ± 0.002
Total effective dose [µSv]	Median 11.6 [IQR 10.9–12.8]
Scout contribution [µSv]	1.7 [IQR 1.5–1.8]
CT-series contribution [µSv]	9.9 [IQR 9.4–11.1]

Key Results

Parameter	Main finding
Clinical cohort	24 scans in 20 children; median age 10 years
Median total PCCT dose	11.6 µSv [IQR 10.9–12.8]
Chest radiograph dose	8.2 µSv [IQR 6.2–13.6], p = 0.007
Immediate diagnostic adequacy	All 24 scans sufficient without immediate repeat standard-dose CT
Best-rated indications	Focal abnormalities, known-lesion follow-up, congenital diaphragmatic hernia follow-up, ILD follow-up
Lower-confidence indications	Ruling out previously unknown ILD or bronchiectasis

Source:
Limantoro I, Torfs K, Binst J, Proesmans M, Breysem L, Bosmans H, Aertsen M. Next-gen paediatric imaging: ultra-low dose chest photon-counting CT approaching chest radiograph doses. European Radiology Experimental. 2026;10:119. doi:10.1186/s41747-026-00783-2.