Patient radiation exposure and image quality evaluation with the use of iDose4 iterative reconstruction algorithm in chest-abdomen-pelvis CT examinations

Abstract

The aim of this study is to evaluate the effect of iDose(4) iterative reconstruction algorithm on radiation dose and imaging quality at chest-abdomen-pelvis (CAP) CT examinations. Seventeen patients were considered; all patients had a previous CT scan with the standard filter back-projection (FBP) protocol and a follow-up scan with the iDose(4) protocol at the same scanner. Image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were objectively calculated. Two radiologists evaluated noise, sharpness, contrast, diagnostic confidence and artefacts. Radiation exposure quantities were calculated. iDose(4) resulted in 46 % dose reduction combined with significantly lower noise and higher SNR and CNR compared with FBP. iDose(4) images had significantly lower subjective image noise and enhanced sharpness and contrast. Diagnostic confidence was high and image artefacts were minor for both algorithms. iDose(4) provides great potential for reducing patient radiation burden while improving imaging quality in CAP CT examinations.

Iterative Reconstructions in Reduced-Dose CT

“…An evaluation of the 50% dose CT protocol by our four readers confirmed these findings, as diagnostic confidence was maintained and the subjective image quality of the reduced-dose images was still above average when compared to the reference, 100% dose images. Thus, in agreement with other authors (9,10,16,17,20,21,24,29), we think that routine follow-up in oncology patients with 50% reduced-dose CT is feasible, provided that IR algorithms are employed. We are the first to prospectively compare reduced-dose MBIR and ASIR images in young oncology patients, for whom the decrease in overall cumulative radiation exposure represents a major concern.…”

“…The pixelated blotchy appearance is a unique feature resulting from the MBIR mode and appears on CT images as small steps at tissue interfaces. This may affect the sharpness of the anatomical structures upon visualization (10,15,26). Finally, the overall diagnostic confidence of each thoracic and abdominal CT acquisition was evaluated using a 4-point scale (1 = fully confident, 2 = probably confident for diagnostic interpretation, 3 = confident only under limited conditions for visualization of abnormalities, and 4 = unacceptable).…”

“…These methods do not blend with FBP and provide a greater noise reduction than firstgeneration IR methods. Thus, MBIR (VEO, GE Healthcare) enables a greater reduction of the associated radiation dose (7)(8)(9)(10)(11)(12).…”

“…The potential for dose reduction using IR while preserving image quality has already been the subject of several publications (8,11,(13)(14)(15)(16)(17), but only a few studies have analyzed both chest and abdominal CT images (10,(18)(19)(20)(21)(22)(23)(24) and none have focused on young patients. As young patients represent the most radiosensitive population (25), they most urgently require an optimized radiation exposure, especially when they frequently undergo CT examinations, such as for follow-up of oncological disease.…”

Submilisievert ultralow-dose CT colonography using iterative reconstruction technique: a feasibility study

“…For supine (standard dose) acquisition, reconstruction filter C with HIR (iDose 4 , Philips Healthcare, Best, The Netherlands) level 4 was used as this was a routine reconstruction for abdominal scans (6). For prone ultralow-dose series, filter A and either filtered back projection (FBP) or HIR set on the highest level (level 6) were used.…”