CT dose reduction: approaches, strategies and results from a province-wide program in Quebec

Abstract

Many studies have shown a statistically significant increase of life-time risk of radiation-induced cancer from CT examinations. In this context, in Canada, the Quebec's provincial clinical center of expertise in radiation safety (CECR) has led a province-wide tour of 180 CT installations in order to: (i) evaluate the technical and functional performance of CT scanners, (ii) evaluate and improve radiation safety practices and (iii) initiate, with local teams, a CT dose optimization process. The CT tour consisted of a two day visit of CT installations by a CECR multidisciplinary team of medical physicists, engineers and medical imaging technologists (MITs) carried out in close collaboration with local teams composed of MITs, radiologists, physicists, engineers and managers. The CECR has evaluated 112 CT scanners since 2011. Optimization of CT protocols was performed in all centers visited. The average dose reduction obtained from optimization was [Formula: see text], [Formula: see text] and [Formula: see text] for adult head, thorax and abdomen-pelvis, respectively. The main recommendations often made by the CECR experts were: (1) the implementation of low-dose protocols for the follow-up of pulmonary nodules and for renal calculi, (2) the compliance to the prescribed scan range as defined by local guidelines, (3) the correct positioning of patients and (4) the use of bismuth shielding to reduce the dose to radiosensitive organs. The CECR approach to optimize CT doses to patients is based on the active participation of local stakeholders and takes into account the performance of CT scanners. The clinical requirements as expressed by radiologists remain at the core of the optimization process.

Effects of dose reduction on bone strength prediction using finite element analysis

“…However, the accuracy and reliability of FE-predicted bone strength have been demonstrated in several studies162945. Also, this study only considered CT dose reduction via the variation of tube current but dose can also be reduced by reducing tube voltage or increasing pitch38 for instance. Nevertheless, variation of tube current is the most prevalent method for CT dose reduction22.…”

“…In developed countries, the use of CT is known to account for almost 17% of all radiological examinations, but is attributed to 47% or higher of medical radiation dose38. With such an alarming contribution, it is necessary to evaluate the efficacy of routine CT imaging.…”

An Environmental Scan of the National and Provincial Diagnostic Reference Levels in Canada for Common Adult Computed Tomography Scans

“…DRLs were obtained for British Columbia [16], Quebec [17,18], Saskatchewan [19,20], Nova Scotia [21], Manitoba [22], and Ontario [23]. HC13 includes data from all provinces, Yukon Territory, and Northwest Territories.…”

“…Redundant data (such as that from Saskatchewan and Quebec) was maintained to allow for visualization of any changes within the years. Furthermore, QC10 was a study that used only 2 hospitals' data [17], while QC08 and QC14 were for the entirety of the province [18]. ON13's data was gathered from only one site at St. Michael's Hospital in Toronto [23].…”

“…Consistent monitoring can assist in reaching a DRL reflective of the ALARA principle. New technology including iterative reconstruction algorithms including adaptive iterative reconstruction and model-based iterative reconstruction [29], high detective quantum efficiency detectors [18], noise reduction filters [30], and automatic exposure control [30] can dramatically decrease the dose associated with an imaging exam and yield much more acceptable doses. Sites with better technology can have lower local DRLs, so long as they are used.…”