Radiation exposure of patients undergoing nuclear medicine procedures in Germany between 1996 and 2000

Nuklearmedizin in Deutschland

Aim: To explain the spectrum and number of in-vivo nuclear medicine examinations and therapies based on official statistics about out-patient and in-patient care. Trends in time of the frequency and spectrum of procedures as well as data on the health care structure for nuclear medicine in Germany should be collected. Methods: Data from the Gesundheitsberichterstattung des Bundes, from the frequency statistics of the statutory health insurance for out-patients and from the Bundes - ärztekammer were used. Customized queries were performed to analyse temporal changes. Results: Nuclear medicine physicians are more frequently consulted by out-patients over the last years (2008: 2 024 498; 2009: 2 164 664) and the number of colleagues in private practice increased. For in-patients, the frequency of conventional nuclear medicine procedures (mainly for brain, lymphatic system, lung and heart) increased since 2008 after a decline in previous years (2009: 323 515; +4.6%) and the number of PET(/CT) examinations continued to rise (2009: 25 123; +18%), even if changes in OPS keys may hamper comparisons. Nearly 600 gamma cameras and 76 PET(/CT) scanners were installed in hospitals in 2008. Nuclear medicine procedures are increasingly performed as cross sectional imaging like SPECT(/CT) and PET(/CT). With the supply shortfall with 99Mo, the frequency of thyroid scans with 123I iodine increased as well as the use of 18F PET as a substitute for conventional bone scans. The number of radionuclide therapies, in particular non-thyroid treatments, increased since the mid-nineties and stabilized at nearly 50 000 cases per year with shorter lengths of stay. Conclusion: The details of the present analysis may help to understand the positive evolution of key numbers for nuclear medicine.

[Nuclear Medicine in Germany. Updated key data and trends from official statistics]

AIM

Updated presentation of the spectrum of nuclear medicine in-vivo examinations and therapies from officially available statistics on out-patient and in-patient care as well as trends of structural data on nuclear medicine in Germany.

METHODS

Data from the German Federal Health Monitoring, from the frequency statistics of the statutory health insurance for out-patients and from the German Medical Association were used and supplemented by data from selective literature searches.

RESULTS

In descending order, thyroid, bone and cardiac scans continue to be the most frequent nuclear medicine procedures. With a marked increase of PET/CT and SPECT/CT, the number of basic scintigraphies is declining. Cardiac, lung and brain scans as well as lymph scintigraphies are increasingly requested, bone and thyroid scan decrease. The consultation of nuclear medicine physicians in private practices is increasing by 4 % per year (2009: 2 164 664; 2015: 2 687 359). The number of nuclear medicine physicians in the out-patient sector rose significantly (2009: 756, 2015: 939, growth 24 %) and has remained constant due to restrictions since 2013. The specialist recognitions of women in nuclear medicine increased (proportion currently 46 %). In hospitals, more PET(/CT) scanners (2009: 97; 2015: 125) and fewer gamma cameras (2009: 594; 2015: 550) are operated. The number of non-thyroid (and also out-patient) radionuclide therapies continued to increase.

CONCLUSION

With increased use of hybrid technologies, the nuclear medicine spectrum shows positive trends especially in nuclear cardiology and extra-thyroid therapy. These developments must be taken into account when amending regulations of specialist training and medical student teaching.

The radiation issue in cardiology: the time for action is now

The "radiation issue" is the need to consider possible deterministic effects (e.g., skin injuries) and long-term cancer risks due to ionizing radiation in the risk-benefit assessment of diagnostic or therapeutic testing. Although there are currently no data showing that high-dose medical studies have actually increased the incidence of cancer, the "linear-no threshold" model in radioprotection assumes that no safe dose exists; all doses add up in determining cancer risks; and the risk increases linearly with increasing radiation dose. The possibility of deterministic effects should also be considered when skin or lens doses may be over the threshold. Cardiologists have a special mission to avoid unjustified or non-optimized use of radiation, since they are responsible for 45% of the entire cumulative effective dose of 3.0 mSv (similar to the radiological risk of 150 chest x-rays) per head per year to the US population from all medical sources except radiotherapy. In addition, interventional cardiologists have an exposure per head per year two to three times higher than that of radiologists. The most active and experienced interventional cardiologists in high volume cath labs have an annual exposure equivalent to around 5 mSv per head and a professional lifetime attributable to excess cancer risk on the order of magnitude of 1 in 100. Cardiologists are the contemporary radiologists but sometimes imperfectly aware of the radiological dose of the examination they prescribe or practice, which can range from the equivalent of 1-60 mSv around a reference dose average of 10-15 mSv for a percutaneous coronary intervention, a cardiac radiofrequency ablation, a multi-detector coronary angiography, or a myocardial perfusion imaging scintigraphy. A good cardiologist cannot be afraid of life-saving radiation, but must be afraid of radiation unawareness and negligence.

[Cardiac SPECT/CT: correlation between atherosclerosis, significant coronary artery stenoses and myocardial perfusion parameters in patients with known coronary artery disease]

Invasive coronary angiography (ICA) and CT angiography (CTA) both enable significant coronary artery stenoses to be detected, but they are not suitable for assessing their hemodynamic relevance. This can be accomplished using myocardial perfusion scintigraphy (MPS) which, however, has limited specificity and spatial resolution. Regarding patients with known coronary artery disease (CAD) it is furthermore important to stratify patient's individual risk for severe cardiac events to guide therapy management.The results of our investigations in 158 patients with CAD indicate that global and regional calcium scores (CAC) do not correlate with the presence of myocardial perfusion defects and significant coronary artery stenoses, respectively. However, published literature has reported CAC as being an independent predictor of long-time survival.For clinical purposes it seems that non-invasive diagnostics with CTA, MPS and CAC screening can be useful even in patients with known CAD. CAC and global scar burden enable long-term risk-stratification, whereas fusion of CTA and MPS is useful to detect the culprit lesion of relevant perfusion defects and to select options for revascularization.

Cumulative patient effective dose in cardiology

Medical radiation from X-rays and nuclear medicine is the largest non-natural (man-made) source of radiation exposure in Western countries. The aim of this study was to assess the individual cumulative effective dose in patients admitted to our cardiology ward. We collected a cumulative radiological history from a structured questionnaire and access to hospital records in 50 consecutive adult patients (36 males; age, 66.7+/-10.8 years) admitted to the Institute of Clinical Physiology in Pisa. The cumulative effective dose was assessed as an indicator of stochastic risk of cancer. We derived the effective dose for each individual examination from the Medical Imaging Guidelines of the European Commission (2001). On average, each patient underwent a median of 36 examinations (interquartile range, 23-46). The median cumulative effective dose was 60.6 mSv. Three types of procedures were responsible for approximately 86% of the total collective effective dose: (i) arteriography and interventional cardiology (12% of examinations, 48% of average dose per patient); (ii) nuclear medicine (5% of examinations, 21% of average dose per patient); and (iii) CT (4% of examinations, 17% of average dose per patient). The median estimated extra risk of cancer was approximately 1 in 200 exposed subjects. In conclusion, the average contemporary cardiological patient is exposed to a significant cumulative effective dose from diagnostic and therapeutic interventions. It is important to log cumulative dose for each patient at the time of each examination. Every effort should be made to justify the indications and to optimize the doses.

Radiation dose exposure in multislice computed tomography of the coronaries in comparison with conventional coronary angiography

BACKGROUND

Radiation dose exposure is increased in multislice spiral computed tomography (MSCT) compared to conventional coronary angiography (CXA).

METHODS

Retrospective data analysis of 56 patients (66+/-8 years, 49 males, body surface area 1.98+/-0.18 m(2), heart rate 64+/-11 bpm) who underwent MSCT and CXA was performed (MSCT: 16-slice scanner, rotation time 0.375 s, 120 kV, ECG-pulsing; CXA: current technique system build in 2003). Ten patients with bypass grafts underwent bypass angiography in CXA and MSCT. To compare the radiation doses of both investigations, the effective dose (ED) was chosen as the analysis variable.

RESULTS

The mean ED for MSCT was 9.76+/-1.84 mSv (n=46) for patients without bypass grafts; with calcium scoring the mean ED was 12.46+/-2.23 mSv (n=46). In comparison, the mean ED of CXA was 2.60+/-1.27 mSv (n=46) for patients without bypass grafts; with bypass grafts (n=10) the mean ED for MSCT was 12.95+/-1.75 mSv, for CXA of 6.27+/-4.04 mSv, respectively. In MSCT heart rates of <or=60 bpm resulted in lower mean ED than heart rates of >60 bpm (8.86+/-1.24 mSv versus 10.53+/-1.86 mSv).

CONCLUSIONS

MSCT is still associated with a higher radiation dose exposure than CXA. The radiation dose relation is more favorable for MSCT than for CXA in patients with bypass grafts in comparison to patients without bypass grafts. This study emphasizes the importance of dose reduction techniques.