Radiation dose and image quality for paediatric interventional cardiology

Abstract

Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 microGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 microGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

Biplane interventional pediatric system with cone‐beam CT: dose and image quality characterization for the default protocols

“…Numerical assessments using test object images can help optimize these settings. These measurements and other values reported in the literature 4 , 8 , 25 , 26 should be communicated to cardiologists to help optimize clinical protocols.…”

“…An important aspect for cardiologists to consider is the three to twelvefold increase in the ESAK/frame when comparing cine with fluoroscopy frames. This system can store fluoroscopy runs in DICOM format; therefore, if high image quality is not required, a fluoroscopy run should be considered as an option for documenting part of the procedure (4) . For 22 cm FOV and 4 and 8 cm PMMA, the selection of Ped $<12\hspace{0.17em}\text{kg}$ instead of FL3040 will reduce the ESAK/frame for the cine mode threefold and 2.2‐fold, respectively, for the same fluoroscopy ESAK/frame.…”

“…These tests cover two main aspects: 1) the entrance surface air kerma (ESAK) of an appropriate phantom under normal operating conditions, simulating various patient thicknesses in the commonly used imaging modes: fluoroscopy, cine and, more recently, the three‐dimensional rotational angiography (3D‐RA), also known as cone‐beam CT (CBCT); and 2) image quality assessment (using test objects) for the various imaging protocols used in clinical practice. This physical characterization helps cardiologists select the best protocols and operation modes with sufficient image quality (and appropriate dose) to guide and document the procedures 4 , 5 . This part of the commissioning testing sets the baseline values as a reference for future routine quality control tests (constancy tests) to monitor the most significant system operation parameters to ensure their stability over time.…”

Optimization of dose and image quality of paediatric cardiac catheterization procedure

“…The purpose of this study is to assess the most favourable imaging parameters taking iodinebased contrast agent concentrations into account. A figure of merit (FOM) was defined and measured for a series of conditions [18,19]. Imaging modes were selected among the available modes for paediatric patients, constituting both tube peak voltage and ESAK for fluoroscopic exposures.…”

Estimation of eye lens doses received by pediatric interventional cardiologists

“…In pediatric interventional cardiologists eye lens dose measurement, some of these features may be particularly useful, such as high sensitivity, since patients have a high morphological variability, with generally smaller thickness than in procedures performed in adults. Usually longer interventions are observed, and this procedures are performed using equipment adjusted to low dose rates (Vano et al, 2008).…”