“Green Medical Imaging” – Ultrasound rediscovered as a resource-saving future technology in clinical imaging

Keywords

CO₂ neutrality - ecological sustainability - green Medical Imaging

Introduction

Global warming is one of the greatest challenges of the 21^st 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

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

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]
Production	NA	4.0 kg	6.0 kg
Operation	NA	2.6 kg	14 kg
Total	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

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.

Dr. med. Valentin Blank

Prof. Dr. med. Deike Strobel

Prof. Dr. med. Thomas Karlas

Conflict of Interest

The authors declare that they have no conflict of interest.

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Publication History

Article published online:
12 December 2025