Practical Lessons on Improving Safety, Reproducibility and Efficiency Using a Dose Management Software

Radiology Insights Practical lessons on improving safety, reproducibility and efficiency using a dose management software

Sebastian T. Schindera, MD

Sebastian T. Schindera, MD Clinic of Radiology and Nuclear Medicine at the University Hospital Basel, Switzerland Practical lessons on improving safety, reproducibility and efficiency using a dose management software

>> Compliance While the industry is largely 1. CT Procedure Growth, Implications and Dose self-regulating, new legislation Responsibility introduced by the European Union in 2013 (coming into force in 2018), will Since the introduction by Hounsfield and Based on the rapidly rising frequency of mean that radiologists and clinicians Cormack in 1972, computed tomography CT examinations and the potential risk of will be obligated to document patient (CT) has become one of the most impor- cancer induction, it is the great respon- dose for every diagnostic study with tant modalities in diagnostic imaging sibility of the radiological community, ionizing radiation. due to its strong positive impact on pa- including radiologists, technologists, tient outcome and patient flow. medical physicists and the CT manufacturers, to participate in dose optimization As a result, its utilization increased rap- (Figure 1). idly over the last decades, especially in the industrialized world. For example, in Also, while the industry is largely self- the USA the number of CT investigations regulating, new legislation introduced grew on average 10% annually during by the European Union in 2013 (coming the last 15 years (1) and in Switzerland into force in 2018), will mean that radi- the number of CT examinations rose by ologists and clinicians will be obligated 142% between 1998 and 2008 (2). CT to document patient dose for every di- was responsible for 68% of the yearly agnostic study with ionizing radiation. medical radiation exposure of the Swiss Therefore, besides a rigorous review of population in 2008, although CT only the justification for each CT exam, the contributed 6% of medical studies with radiologist should ensure that patients ionizing radiation (2). undergo a CT examination in accordance with the ALARA principle (as low as rea- Current knowledge on the biological ef- sonably achievable). fects of low level radiation (<100 mSv), which is mostly applied in medical imag- Over the last few years, CT manufacturers ing, and the attributable risk of develop- have focused on the development of very ing cancer by radiation exposure are still effective technologies for dose reduction mainly based on studies on survivors of (e.g. iterative reconstruction, automatic the atomic bomb attacks on Japan in tube current modulation, dose-efficient 1945 (3). However, two recent retrospec- detectors) while preserving the diagnos- tive epidemiologic cohort-studies showed tic information. a correlation between radiation exposure by CT and a slightly increased cancer risk in children and young adults (4, 5).

2 Accordingly, radiology departments have rics, dose tracking can now be done in a spent considerable resources (e.g. time comprehensive and fully automated way. for evaluation and training, financial The analysis of this valuable data offers investment for state-of-the-art equip- radiologists, medical physicists and ad- ment) to improve patient safety in CT. ministrators an opportunity to monitor Unfortunately, the systematic and com- the actual CT dose distributions and helps prehensive measurement of the quality plan evidence based future investments outcome through meaningful indicators (e.g. continuous quality improvement such as CT dose metrics (e.g. volumetric programs, technical developments). CT dose index (CTDIvol), size-specific dose estimate (SSDE), effective dose) has been Besides tracking and analyzing CT doses, often neglected in this context. Radimetrics also offers the opportunity to monitor the productivity and utilized A potential reason for this disregard is capacity of the CT scanners. the very complex and time-consuming work required to manually collect the Following are some practical examples doses from each CT scan performed at an from the University Hospital Basel on im- institution. With the introduction of dose proving patient safety in CT and monitor- management software, such as Radimet- ing productivity with Radimetrics.

Figure 1 The dose management team of the University Hospital Basel analyzing their CT data.

3 2. CT Radiation Dose Management

After the installation of Radimetrics at CT doses for an institution and can result the University Hospital Basel in Septem- in misleading conclusions. ber 2013, we decided to segment the >> Quality management of CT radiation dose into Protocol Management The total dose reduction for a routine CT two parts. We now differentiate between The most dramatic reduction in average of the chest is therefore 53% comparing dose management on an institutional dose was achieved for routine chest CT the data from 2012 with those from level and on a patient examination level. with or without contrast media. Based on 2014. the optimization of the technical param- 2.1 Dose Management at the eters, we were able to reduce the average The average effective dose for a Institutional Level effective dose for a routine CT of the chest routine CT of the chest differed up to Our main objectives of CT dose manage- from 6.4 mSv in 2012 down to 4.0 mSv in 4-fold among the scanners (Figure 2). ment at the institutional level are 2013 and 3.0 mSv in 2014 (Table 1). The Having this important information at total dose reduction for a routine CT of our disposal, young patients are now Q to know the average doses of our the chest is therefore 53% comparing the triaged for a routine CT of the chest to most frequently performed CT proto- data from 2012 with those from 2014. our two high-end CT scanners with the cols at any time for protocol man- goal to deliver the lowest doses for this agement and The average SSDE for the CT of the chest radiosensitive patient group. Q to have the possibility to perform has measured 5.5 mGy in 2014. These meaningful benchmarking. significant results represent an important reassurance for our institution in our Since the dose management software concerted efforts towards dose optimiza- tracks the dose from each CT examination tion over the last two years to achieve and then calculates the average dose for the lowest possible dose for our patients different CT protocols based on hundreds while maintaining diagnostic accuracy. to thousands of CT studies, we now have a global view of our delivered CT doses It also highlights the fact that we are on (Table 1). Using average CT doses, we first the right track. These achievements are compare ourselves to other institutions communicated internally and externally. by using national diagnostic reference Internally, our staff, including radiolo- levels or scientific publications and then gists and technologists, is frequently up- decide if optimization is necessary. dated with key data on CT dose with the goal to confirm the meaningfulness of When performing dose benchmarking, it our ambitious work in dose reduction. is essential to use average dose values based on a large number of CT scans, Focusing on patient safety through best since the patients` habitus can signifi- practice in CT has also led to an increased cantly influence the values of the tho- job satisfaction for our employees. The rax and abdomen with the application external communication of our CT doses of automatic tube current modulation. to our referring physicians and patients, Random examples of just a few CT stud- which is also included in our annual re- ies for dose benchmarking would not port and newsletters, is used as a mar- demonstrate a representative picture of keting tool to demonstrate our patient-

4 centered care. 2.2 Dose Management at the Patient Level for Patient Safety Benchmarking Our main objectives for CT dose man- At our institution, we also benchmark the agement at the patient level are doses between our four CT scanners, since they are not equally equipped with the Q to track cumulative patient effective >> Safety latest technologies for dose reduction. dose for alerting and At our institution, we set a threshold In 2013, two CT scanners were equipped Q to detect dose outliers for follow-up. dose value for each CT protocol using with iterative reconstruction technology the volumetric CT dose index (CTDIvol). and automatic tube current modulation Cumulative Dose Alerting while the other two scanners did not By tracking the patient effective dose we If a dose outlier occurs, then our have those technologies available. aim to avoid unnoticed periodic CT scans dose management team receives an in young patients and patients with automatic email with an electronic link As a consequence, we detected substan- non-malignant disease, especially when to the patient file in Radimetrics. tial differences in the average doses be- non-ionizing imaging modalities (e.g. tween the four CT scanners. For example, MRI, ultrasound) can deliver equivalent the average effective dose for a routine diagnostic information. Before we had CT of the chest differed up to 4-fold Radimetrics, one of our patients received among the scanners (Figure 2). Having a total of 14 CT examinations within 6 this important information at our dis- months and thereby accumulated an ef- posal, young patients are now triaged fective dose of almost 170 mSv (Figure 3). for a routine CT of the chest to our two high-end CT scanners with the goal to de- The CT scans were indicated in the con- liver the lowest doses for this radiosensi- text of a pancreatitis with various com- tive patient group. Furthermore, reliable plications. Without the dose information data demonstrating the effectiveness of from Radimetrics, our radiologist was CT scanners with the latest dose reduc- lacking visibility for the fact that the tion technologies can be adjuvant in the patient`s cumulative radiation dose was decision-making process of an invest- increasing rapidly. After retrospectively ment in a new CT scanner. Based on our reviewing all CT scans, we came to the findings, we purchased a third high-end conclusion that some of those CT scans CT scanner in 2014, resulting in a more could have been replaced by an MRI or harmonized dose distribution among all an ultrasound without impacting patient scanners (Figure 2). management. Based on this incident, we decided to set a dose alert at a cumula- We are also benchmarking against other tive effective dose of 100 mSv. institutions and national dose reference levels and found that our average SSDE This threshold dose is chosen based on for chest CT is 45% below the diagnostic our judgement, as no scientific data on reference level of Switzerland. this topic exists. In the case that a patient exceeds the threshold dose, the information is passed on to our radiology information system so the radiologist is alerted ahead of the next scan and can

5 consider an alternative imaging modal- Such accidents can effectively be pre- ity. vented through a systematic dose management that makes outliers transparent Outlier Follow-up near real-time. At our institution, we set a In addition, we also monitor dose outliers threshold dose value for each CT protocol at the examination level to observe early using the volumetric CT dose index (CTDI- systematic errors, such as an uninten- vol). The threshold value is set at 5 mGy tional selection of the wrong technical above the national diagnostic reference settings. level, which was chosen arbitrarily since no guidelines exist. This has happened in different institutions in the USA between 2008 and For example, the diagnostic reference lev- 2009, where wrong technical parameters el for a routine CT of the chest in Switzer- were stored for CT perfusion of the head land is 10 mGy, so we set the threshold and over 200 patients received an up to at 15 mGy. If a dose outlier occurs, then 8-fold higher dose than necessary. The our dose management team receives an systematic error remained undetected for automatic email with an electronic link 18 months until patients returned with to the patient file in Radimetrics. deterministic effects such as hair loss around their head (6).

Year 2014 Year 2012 Year 2013 (1. - 3. Quarter) Total number of CT Scans 19,220 21,733 16,993 Average effective dose per CT scan 7.6 mSv 6.2 mSv 5.5 mSv Routine CT head Total No of CT-scans 4,417 5,658 4,078

Mean CTDIvol 58.5 mGy 45.0 mGy 41.4 mGy Mean DLP 1164 mGy∙cm 886 mGy∙cm 792 mGy∙cm Mean ED 3.8 mSv 2.9 mSv 2.7 mSv Routine CT chest Total No of CT-scans 820 1,043 686 Mean SSDE 11 mGy 7.2 mGy 5.6 mGy

Mean DLP 312 mGy∙cm 195 mGy∙cm 155 mGy∙cm

Mean ED 6.4 mSv 4.0 mSv 3.0 mSv Routine CT abdomen-pelvis Total No of CT-scans 1,173 1,225 998 Mean SSDE 16.7 mGy 14.4 mGy 13.4 mGy Mean DLP 802 mGy∙cm 563 mGy∙cm 502 mGy∙cm Mean ED 12.0 mSv 9.6 mSv 8.3 mSv CT abdomen-pelvis for urolithiasis Total No of CT-scans 629 780 533 Mean SSDE 7.9 mGy 5.5 mGy 5.2 mGy Mean DLP 393 mGy∙cm 224 mGy∙cm 209 mGy∙cm Mean ED 5.4 mSv 3.1 mSv 2.9 mSv

Table 1 CT Dose statistics between 2012 and 2014 from the University Hospital Basel assessed with Radimetrics.

6 2013 2014

Figure 2 The average effective doses for routine CT of the chest evaluated for four CT scanners. In 2013 two CT scanners used iterative reconstruction technology and in 2014 there were three scanner equipped with iterative reconstruction technology.

Figure 3 The dose page of a patient who had a pancreatitis with mulptiple complications. The patient received 14 CT scans within 6 months and built up a cumulative radiation dose of almost 170 mSv.

7 3. Business Intelligence with Radimetrics for Efficiency Management

Between January 2012 and September we notice the trends towards an increase >> Efficiency 2014, we performed almost 60,000 CT or decrease in productivity very early. For example, we monitor the overall scans at our institution (Table 1). Radi- Therefore, we have the possibility to react productivity of our CT team and metrics automatically transforms the in a timely fashion, for example to redi- scanners within specific time periods. large amount of collected data into rect patients to less busy CT scanners or meaningful information, so it can be do analysis the reasons of a break-in in The developments of productivity can analyzed by the radiologists and admin- CT referrals. be further analyzed by the type of CT istrators. scan and most importantly also by the The developments of productivity can be referring physicians. For example, we monitor the overall pro- further analyzed by the type of CT scan ductivity of our CT team and scanners and most importantly also by the refer- within specific time periods (e.g. per year, ring physicians. We also monitor the month, week and day) (Figure 4). Since utilized capacity of our four CT scanners the data is presented almost in real-time, with the goal to reduce idle time.

Figure 4 The productivity of four CT scanners on a day-to-day basis within one month.

8 4. Conlusion

Radimetrics visualizes and analyzes the At the same time, the productivity of an huge amount of dose data from CT in institution can be also examined. Thus, a very meaningful way to support the the added value by Radimetrics results radiological community in the process of in improved patient safety, reproducible dose reporting and optimization. quality and departmental efficiency.

9 5. References

1. Mettler FA, Jr., Bhargavan M, Faulkner K, Gilley DB, Gray JE, Ibbott GS, et al. Radiologic and nuclear medicine studies in the United States and worldwide: frequency, radiation dose, and comparison with other radiation sources--1950-2007. Radiology. 2009 Nov;253(2):520-31. 2. Aroua A, Samara ET, Bochud FO, Meuli R, Verdun FR. Exposure of the Swiss population to computed tomography. BMC medical imaging. 2013;13:22. 3. Preston DL, Ron E, Tokuoka S, Funamoto S, Nishi N, Soda M, et al. Solid cancer incidence in atomic bomb survivors: 1958-1998. Radiation research. 2007 Jul;168(1):1-64. 4. Pearce MS, Salotti JA, Little MP, McHugh K, Lee C, Kim KP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet. 2012 Aug 4;380(9840):499-505. 5. Mathews JD, Forsythe AV, Brady Z, Butler MW, Goergen SK, Byrnes GB, et al. Cancer risk in 680,000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. Bmj. 2013;346:f2360. 6. Alan Zarembo Cedars-Sinai investigated for significant radiation overdoses of 206 patients, Los Angeles Times, October 10, 2009

About the Author

Sebastian T. Schindera, MD Q Associate professor for Radiology, Director of CT, attending physician at University Hospital Basel Q Subspecialized in Abdominal Imaging (trained at the University of Toronto) Q Worked at four University Hospitals in Switzerland, USA, Canada (University Hospital of Bern, Duke University, University of Toronto, University Hospital Basel) Q CT Research on dose optimization and dual-energy

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