Feature | July 23, 2013| Dave Fornell

Not Everyone is on the Same Page to Lower Radiation Dose

Finding ways to lower patient radiation dose from both medical imaging and interventional cardiology has become a major trend. However, when vendors start talking dose, it is important to realize there are no set industry standards agreed upon by manufacturers to calculate dose. For this reason, I call into question vendors’ statistics of how much their technology can lower dose by up to 20, 50 or even 80 percent.  While new technologies such as iterative reconstruction, more sensitive detectors and ECG gating do indeed lower dose, quantifying it can be a moving target. 

DAIC created a comparison chart for technologies to help lower computed tomography (CT) dose (see Page 34).  Vendors were asked, “How does your system calculate estimated dose?” As an example, we asked what they use as a conversion factor to calculate dose in MilliSieverts (mSv) based on dose-length product (DLP) or CT dose index volume (CTDlvol) found on a scan’s DICOM header.  To our surprise, this central question of how vendors arrive at their dose statistics was not answered by anyone. I wrote back posing this question again and only received responses from GE and Philips — the rest declined to comment.  The bottom line is that there are no industry standards agreed upon by manufacturers. 

“There have been publications to estimate effective dose from DLP or CTDI through conversion factors and there are organ dose simulations you can calculate using Monte Carlo techniques, however each method has its own level of uncertainty,” said Leslie Lakis, Philips senior public relations manager, imaging systems. “Therefore, physicists are left to use whatever effective dose conversion they prefer until the scientific community formally adopts a standard method for effective dose conversion.”

Ken Denison, global marketing director, CT, global MICT dose leader, GE Healthcare, said each manufacturer takes measurements on 16 and 32 cm water phantoms for a range of parameters (kVp, mA, slice thickness, pitch, etc.) and this allows them to then estimate the exposure using CTDIvol. However, he said GE does not provide an estimate for whole-body effective dose on its systems. “This is because there are different k-factors that may be used to convert DLP to and estimate of whole-body effective dose. Different users may choose which factors to use differently,” he said. 

Due to the variability cited, I often wonder if true apples-to-apples comparisons between vendors’ technologies are possible. Also, as more states consider laws requiring providers to record patient dose, what measure is being used?  It must be realized that all dose calculations are based on 16 and 32 cm phantoms, which are are not real people and most patients are 16 or 32 cm across. In addition, each patient body habitus impacts the individual level of dose, so all dose measures are really a best guess, not an exact science.

Related Content

3-D-printed Model of Stenotic Intracranial Artery Enables Vessel-Wall MRI Standardization
News | 3-D Printing| April 18, 2017
A collaboration between stroke neurologists at the Medical University of South Carolina (MUSC) and bioengineers at the...

Physicians will need to use a CMS-certified appropriate use criteria (AUC) clinical decision support software that documents the appropriateness of an imaging order to receive full reimbursement for Medicare patients starting Jan. 1, 2018.

Feature | Cardiac Imaging| April 18, 2017 | Dave Fornell
As part of U.S. healthcare reform efforts, starting Jan.
3-D Printed Patch Can Help Mend a ‘Broken’ Heart

This photo shows the 3D-bioprinted cell patch in comparison to a mouse heart. When the patch was placed on a live mouse following a simulated heart attack, the researchers saw significant increase in functional capacity after just four weeks. Image courtesy of Patrick O’Leary, University of Minnesota.

News | Stem Cell Therapies| April 18, 2017
April 18, 2017 — A team of biomedical engineering researchers, led by the University of Minnesota, has created a revo
University of California Study Searches for Consistent CT Dose Best Practices
News | Radiation Dose Management| April 17, 2017
A new study led by UC San Francisco has found that radiation doses can be safely and effectively reduced – and more...
cardiac CT showing a severe right coronary artery lesion on a Toshiba Aquillion One

A cardiac CT showing a severe right coronary artery lesion on both 3-D and curved multiplanar reconstructions from a Toshiba Aquilion One CT system. The newest generation of CT scanners have very fast gantry speeds to freeze cardiac motion, improved image quality and much lower doses than previous generation scanners from a decade ago.

Feature | CT Angiography (CTA)| April 13, 2017 | Dave Fornell
Cardiac computed tomography (CT) imaging really took off a decade ago with the introduction of 64-slice scanners, whi
Toshiba Medical Launches Aquilion Lightning CT System
News | Computed Tomography (CT)| April 12, 2017
April 12, 2017 — Providers can now offer enhanced care and safe imaging to patients with a compact and economical sol
FDA Clears Siemens Somatom go. CT platform
Technology | Computed Tomography (CT)| April 11, 2017
The U.S. Food and Drug Administration (FDA) has cleared the Somatom go. computed tomography (CT) platform from Siemens...
SCCT, Toshiba Medical, partnership, residents-in-training
News | Computed Tomography (CT)| April 05, 2017
The Society of Cardiovascular Computed Tomography (SCCT) and Toshiba Medical announced a new partnership dedicated to...
Bayer, Radimetrics Enterprise Platform, radiation dose management, Connecticut Hospital Association, statewide repository
News | Radiation Dose Management| March 30, 2017
The Connecticut Hospital Association (CHA) and Bayer announced an alliance to establish the United States' first-ever...
Toshiba, Aquilion One CT, model-based iterative reconstruction, MBIR, ACC 2017, FIRST, RSNA 2017
News | Computed Tomography (CT)| March 21, 2017
March 21, 2017 — Toshiba Medical demonstrated its Forward projected model-based Iterative Reconstruction SoluTion (FI
Overlay Init