Keywords
CO₂ neutrality - ecological sustainability - green Medical Imaging
Introduction
Global warming is one of the greatest challenges of the 21st century, with far-reaching consequences for the environment, society and, last but
not least, healthcare [1].
While the effects of climate change on human health are already being widely analysed
and debated, the healthcare sector itself is increasingly coming under scrutiny as
a contributor to the environmental crisis [2]. The healthcare sector is responsible for around 4.4 % of global CO₂ emissions worldwide
– and the trend is pointing higher still [2]. In particular, imaging procedures such as magnetic resonance imaging (MRI) and
computed tomography (CT) are characterised by high energy consumption, complex infrastructure
requirements and, in some cases, environmentally relevant consumables. The use of
these resource-intensive imaging methods has also risen significantly in recent years,
in particular due to growing diagnostic demands and not least to increasing availability
[3].
“Green Medical Imaging” is a new approach in which ultrasound imaging in particular
can be distinguished as a resource-conserving and forward-looking imaging method.
As a radiation-free, widely available and energy-efficient procedure, ultrasound not
only provides clinically valuable information in real-time and in direct contact between
clinician and patient but has been shown to cause significantly less environmental
pollution compared to CT and MRI [4]
[5].
The aim of this editorial is to raise awareness of the ecological dimension of medical
imaging and to show concrete potential savings for climate-relevant emissions through
the increased use of ultrasound. The implementation of sustainable imaging strategies
should in particular also stimulate debate about the extent to which the routine use
of high-precision and resource-intensive imaging methods in modern medicine is always
clinically justified and proportionate.
Use and value of imaging procedures in modern medicine
Use and value of imaging procedures in modern medicine
Imaging procedures are integral to the treatment and diagnosis of a wide range of
diseases and are indispensable in modern oncology and emergency medicine [6].
Based on WHO data, over 3.6 billion imaging procedures are performed worldwide each
year [7]. By way of example, in England, diagnostic ultrasound (US) accounts for 23 % of
these examinations, computed tomography (CT) for 16 % and magnetic resonance imaging
(MRI) for 9 %. Conventional X-ray examinations account for the largest proportion
(47 %) [3].
The continuously rising number of imaging examinations is paralleled by an increase
in examinations that are medically inappropriate or of limited value. A systematic
review conducted in 2024 showed that up to $2 billion are spent annually on “low-value
imaging”. Reducing these examinations could have saved up to 95 % of costs and avoided
the consumption of environmentally relevant resources [4].
Comparison of the environmental impact of different imaging procedures
Comparison of the environmental impact of different imaging procedures
Choosing the right imaging procedure has a significant impact on the environmental
balance in clinical practice: Ultrasound-based imaging methods are characterised by
relatively low acquisition and maintenance costs and minimal resource consumption.
The particularly favourable CO₂ balance of ultrasound imaging is not only due to the
low power consumption but also to the possibility of “bedside” or point-of-care application,
which among other measures can reduce internal transport routes [8]. In both equipment production and disposal, the CO₂ emissions are also significantly
lower compared to other technologies ([Table 1]). In addition, ultrasound devices are generally more durable and can continue to
be used on various wards or for training purposes over the course of their life cycle.
Their wide availability in outpatient and inpatient settings allows efficient care
and thus also reduces the length of patient stays and transport routes, which in turn
reduces CO₂ emissions and hospital costs [9]. Another benefit is that sonographic procedures do not require iodine- or gadolinium-based
contrast agents [10], which further reduces the burden on patients and the environment. Furthermore,
the structural demands of ultrasound are much more environmentally friendly than those
of cross-sectional imaging, as the setup requires less space, releases less heat and
does not require complex lead shielding.
Table 1
Comparison of resource consumption of imaging procedures. US = ultrasound; CT = computed
tomography; MRI = magnetic resonance imaging; MTA = medical technical assistant; NA = not
available.
|
US
|
CT
|
MRI
|
|
Acquisition costs
|
Low
( € 50,000–150,000)
|
High
(approx. € 500,000)
|
Very high
(from € 1 million)
|
|
Maintenance costs
|
Low
|
Moderate
|
High
|
|
CO2 consumption in kg
per examination [15]
|
|
|
|
|
|
NA
|
4.0 kg
|
6.0 kg
|
|
|
NA
|
2.6 kg
|
14 kg
|
|
|
0.5–0.65 kg
|
6.6 kg
|
20 kg
|
|
Energy consumption per examination, taking into account energy consumption over the entire life cycle
[19]
|
Very low standby power consumption (low wattage)
|
Approximately 24–34 kWh, only about 1.6 % of the total energy consumption is required
for the actual image generation [20]
|
104 kWh, where approx. 29 kWh applies to energy consumption within the hospital itself
and 75 kWh to production, transport, etc. [21]
|
|
Contrast agent exposure
|
Greenhouse gas
|
Iodin-based contrast agents
|
Environmental gadolinium pollution
|
|
Availability
|
Very high, bedside examination
|
Good availability
|
Varied, more central locations
|
|
CO2 emission from patient transport
|
Low transport costs
|
Centralised, but readily available
|
Often requires longer journeys
|
|
Personnel costs
|
1 qualified examiner sufficient
|
MTAs + physician required
|
Significant staffing requirements
|
|
Consumables
|
Low
|
Moderate (e. g. structural measures required)
|
High (e. g. cooling required)
|
|
Disposal
|
Easy to dispose of
|
Lead parts, dismantling required.
|
Complex (helium, heavy load transport)
|
Another relevant aspect is the diagnostic focus: In contrast to large-volume CT scans
or multiparametric MRI protocols, ultrasound frequently focuses on a particular clinical
question that can be specifically answered by the experienced attending clinician.
The direct medical classification of clinically irrelevant secondary findings in dialogue
with the patient during the ultrasound examination can avoid potentially costly, energy
demanding follow-up examinations that are often a burden for the patient. “This is
particularly relevant in urgent care settings, where imaging examinations are often
‘indispensable’ for diagnosis and treatment decisions” [11].
Computed tomography (CT) requires more resources than ultrasonography. Alongside higher
purchasing and maintenance costs, electricity consumption and the frequent use of
iodine-based contrast agents contribute to CO₂ emissions and environmental pollution.
Patients are subjected to relevant radiation exposure, increasing long-term health
risks and thus indirectly contributing to additional future resource needs [12].
Magnetic resonance imaging (MRI), along with special nuclear medicine methods, has
the highest acquisition and operating costs as well as the highest energy consumption
of all clinically relevant imaging procedures. Its high energy consumption, the need
to cool the equipment with liquid helium, the complex recycling process and the use
of gadolinium-based contrast agents have a negative effect on the CO₂ balance and
environmental compatibility [10]. The elaborate logistics often result in waiting times that can prolong hospital
stays. Targeted optimisation, for example by reducing idle times, therefore has considerable
potential for reducing environmental pollution and operating costs [13].
Need for a new “scale of assessment” in medical imaging
Need for a new “scale of assessment” in medical imaging
In view of the increasing environmental and economic challenges in the healthcare
sector, it seems appropriate to rethink the evaluation standard for imaging procedures,
which has so far been largely based on technology. In future practice, the default
option should no longer be exclusively the “technically best” and most complex procedure,
but rather the option that is “good enough” in the context of the clinical question
– while ensuring the lowest possible resource consumption. In many cases, ultrasound
imaging meets these requirements precisely: targeted, efficient, cost-effective and
with a minimal CO₂ footprint. A greater focus on sustainability and cost-effectiveness
criteria in healthcare guidelines and decision algorithms could therefore make an
important contribution to the environmental transformation of the healthcare sector
– without compromising the quality of care. Thus, the idea of “choosing wisely” –
including ecological considerations – should be more widely applied in medical imaging
[14].
Summary
As social and political debate on the environmental footprint of healthcare continues
to grow, the environmental footprint of imaging procedures is also becoming more and
more important. In this context, ultrasound diagnostics offer a number of benefits
that go beyond the familiar avoidance of radiation exposure. Thus, ultrasound imaging
requires substantially less energy, both in its manufacture and its use. In comparison,
the CO₂ demand is significantly lower than that of CT or MRI systems – the latter
being particularly resource-intensive in this respect [15].
Furthermore, the ready availability and increasing use of bedside ultrasound enable
prompt and focused diagnostic assessment [16]. This reduces the need for further investigations, which are frequently triggered
by nonspecific side effects in CT and MRI. Last but not least, diagnostic ultrasound
also offers structural and economic advantages: The comparatively low investment and
operating costs as well as the lower personnel requirements contribute to sustainable
process optimisation. Despite the above aspects, clinical indication and diagnostic
requirements should always remain crucial considerations when selecting which procedure
to employ. The quality of the findings is always linked to technical expertise, which
requires in-depth training, especially for sonographic procedures.
Outlook
The targeted and selective use of imaging procedures also offers a significant future
savings potential for the environmental impact. Recent studies show that about 20–50 %
of the examinations carried out have little diagnostic benefit or may even be unsuitable
for the particular question [17]. Therefore, the greatest potential for reducing CO₂ emissions is the consistent
avoidance of unnecessary examinations (“Choosing Wisely” initiative) [14]. Establishing clinical guidelines, standardised indication criteria [18] and decision-making aids could significantly contribute to optimising the process.
In summary, the conscious use of medical imaging as well as technological and organisational
innovations offer great potential for more sustainable, resource-saving and at the
same time high-quality patient care.
