Daily Bulletin 2015

How Low Can You Go? New IR System Drops Dose by Nearly 96 Percent in Pediatric Patients

Monday, Nov. 30, 2015

With the help of new imaging protocols and a state-of-the-art interventional radiology (IR) system, researchers at Cincinnati Children's Hospital have reduced radiation dose to pediatric patients during IR venous procedures by as much as 96 percent, according to the presenter of a Sunday session.

Timothy Singewald, M.D.

Timothy Singewald, M.D.

Timothy Singewald, M.D., conducted a retrospective review of (IR) venous procedures performed on pediatric and young adult patients using two different imaging systems manufactured by Philips Healthcare: the new low-dose IR radiology system AlluraClarity and the hospital's former system, AlluraXper.

The AlluraClarity system, including more aggressive beam filtration and a lower tube current, demonstrated a dose reduction of 75 percent in adult populations. Before the system was on the market, Dr. Singewald and colleagues were able to work with the new low-dose system in the hospital's Interventional Translational Research and Simulation Lab to drop the rate even further.

"We were able to develop new protocols using this AlluraCalarity system that further reduced radiation dose to up to 95 percent, without degrading image quality," said Dr. Singewald, a fellow in pediatric interventional radiology at Cincinnati Children's Hospital.

To evaluate the new acquisition settings — which included additional Cu filtration, further decreasing mA and a small focal spot to compensate for image noise and improve sharpness — Dr.Singewald analyzed retrospective data on 12 patients who underwent 19 IVC filter placement and/or retrieval (between 9 and 35 years of age) procedures and 7 patients (between the ages of 15 and 18) undergoing 12 extremity thrombolysis procedures on the new low-dose system.

"We chose to evaluate the doses for a relatively low-dose venous procedure, the IVC filter placement/retrieval, and the relatively high-dose lower extremity thrombolysis, to show the spectrum of potential dose reduction," he said.

A comparable cohort of patients who had undergone the same procedures on the hospital's former IR system comprised 14 patients who had a total of 21 IVC filter placements or retrievals and five patients who underwent 12 thrombolysis procedures. Comparisons were then made between the groups, including total procedure dose, as measured by cumulative dose area product (DAP), DAP for the fluoroscopy portion of the procedure and DAP for the digital subtraction angiography (DSA) portion of each procedure.

Total procedure radiation doses were substantially reduced using the enhanced low-dose system compared to the reference system for both the IVC filter placement/retrieval and thrombolysis procedures. For IVC filter placement/retrieval, the median DAP was 3.5 Gy.cm2 for the low-dose system versus 30.9 Gy.cm2 for the reference system, yielding an 89 percent dose reduction with the new system. For thrombolysis, the median cumulative DAP was 25 Gy.cm2 using the low-dose system versus 409 Gy.cm2 for the reference system, resulting in a 94 percent dose reduction.

"With new low-dose systems, dramatic dose reduction with no loss in diagnostic quality is possible for pediatric patients and young adults, which is good for patients and everyone in the IR room," Dr. Singewald said.

Historically, DSA has accounted for a greater portion of the radiation dose during venous IR procedures. But with the new low-dose system, the dose during the DSA portion was reduced below that of the fluoroscopic portion of the exam, he said.

Dose reductions were reported for both the fluoroscopic and DSA portions of both procedures on the new system, with the greatest reductions — 96 percent for each — achieved during the DSA portions of the procedures.

Images from Digital Subtraction Angiography (DSA) runs acquired during IVC filter placement and thrombolysis in four different patients. Use of the enhanced low-dose interventional system (AlluraClarity, Philips Healthcare, Best, The Netherlands) resulted in dose reductions of 96 percent for IVC filter placement and 93 percent for thrombolysis when compared to similar cases performed on a former interventional system as a reference (AlluraXper, Philips Healthcare, Best, The Netherlands).

Question of the Day:

We just purchased a new CT scanner from a different vendor and it's like trying to learn a new language to understand their parameters. How do I learn the new nomenclature?

Tip of the day:

Even if it is your personal lead apron, if it is stored on-site at the clinic, it must be checked annually as part of a quality assurance program.

The RSNA 2015 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Oak Brook, IL 60523.