Invasive Imagination and its Agential Cuts

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Invasive Imagination and its Agential Cuts

Jara Rocha, Femke Snelting

<a id="ii-69-1" href="#Item_Index">Item 069</a>

There is a conversation missing on the politics of computer tomography, on what is going on with data captured by MRI, PET and CT scanners, rendered as 3D-volumes and then managed, analyzed, visualized and navigated within complex software environments. By aligning medical evidence with computational power, biomedical imaging seems to operate at the forefront of technological advancement while remaining all too attached to Modern gestures of cutting, dividing and slicing. Computer tomography actively naturalizes Modern regimes such as Euclidean geometry, discretization, anatomy, ocularity and computational efficiency to create powerful political fictions: invasive imaginations and inventions that provoke the technocratic and scientific truth of so-called bodies. This text is a call for trans*feminist[1] software prototyping, a persistent affirmation of the possibilities for radical experimentation, especially in the hypercomputational context of biomedical imaging.

1. Slice

In which we follow the emergence of a slice and its encounters with Euclidean geometry.

The appearance of the slice in biomedical imaging coincides with the desire to optimize the use of optical microscopes in the 18th century. Specimen were cut into thin translucent sections and mounted between glass, to maximize their accessible surface area and to be able to slide them more easily under the objective. Microtomography (after “tomos” which means slice in Greek), seems at first sight to be conceptually coherent with contemporary volumetric scanning techniques and computer tomography. But where microtomography produces visual access by physically cutting into specimen, computer tomography promises to stay on the outside. In order to affectively and effectively navigate matter, ocularity has been replaced by digital data-visualisation.

In computer tomography, “slice” stands for a data entity containing total density values acquired from a cross-section of a volume. MRI, PET or CT scanners rotate around matter conglomerates such as human bodies, crime scenes or rocks to continuously probe their consistency with the help of radiation.[2] The acquired data is digitally discrete but spatially and temporally ongoing. Only once turned into data, depths and densities can be cut into slices, and computationally flattened onto a succession of two-dimensional virtual surfaces that are back-projected so that each eventually resembles a contrasted black and white X-ray. Based on the digital cross-sections that are mathematically aligned into a stack, a third dimension can now be reverse-engineered. This volumetric operation blends data acquired at different micro-moments into a homogeneous volume. The computational process of translating matter density into numbers, re-constructing these as stacks of two-dimensional slices and then extrapolating additional planes to re-render three-dimensional volumes, is the basis of most volumetric imaging today.

Tomography emerged from a long-standing techno-scientific exploration that was fueled by the desire to making the invisible insides of bodies visible. It follows the tradition of anatomic experiments into a “new visual reality” produced by early x-ray imagery.[3] The slice was a collective invention by many: technologists, tools, users, uses, designers and others tied the increasing availability of computational capacity and to the mathematical theorem of an Austrian mathematician and the standardization of radio-densities.[4] Demonstrating the human and more-than-human entanglements of techno-scientific streams, the slice invoked multiple pre-established paradigms to provoke an unusual view on and inside of the world. Forty years later, most hospitals in the Global North have MRI and CT scanners operating around the clock.[5] In the mean time, the slice became involved in the production of multiple truths, as tomography was propagated along the industrial continuum of 3D: from human brain imaging to other influential fields of data-extraction such as mining, border-surveillance, mineralogy, large-scale fishing, entomology and archaeology.[6]

The acceleration produced by the probable jump from flattening x-rays to the third dimension can hardly be overestimated, a jump which is made even more useful because of the alleged “non-invasive” character of this technique: tomography promises visual access without the violence of dissection. Looking at the insides of a specimen which was traditionally conditioned by its death or by inducing an-aesthesia, does not anymore require physical intervention.[7] But the persistence of the cross-cut, the fast assumptions that are made about the non-temporality of the slice, the supposed indexical relation they have to matter, the way math is involved in the re-generation of densities and the location of tissues, all of it makes us wonder about the not-non-invasiveness of the imagination at work in the bio(info)technological tale. Looking is somehow always already an operation.

Tomographic slices necessitate powerful software platforms to be visualized, analyzed, rendered and navigated. We call such platforms “powerful” because of their extensive (and expensive) computational capacities, but also because of ways they embody authority and truth-making. Software works hard to remove any trace of the presence of the scanning apparatus and of the mattered bodies that were once present inside of it. For slices to behave as a single volume that is scanned at a single instant, they need to be normalized and aligned to then neatly fit in the three orthogonal planes of X, Y and Z. This automated process of “registration” draws expertise from computer vision, 3D-visualisation and algorithmic data-processing to stack slices in probable ways.

From here on, the slices are aligned with the rigidity of Euclidean geometry, a mathematical paradigm with its own system of truth, a straight truth.[8] It relies on a set of axioms or postulates where the x, y and z axes are always parallel, and where all corpo-real volumes are located in the cubic reality of their square angles.[9] For reasons of efficiency, hardware optimization, path dependency and compatibility, Euclidean geometry has become the un-questionable neutral spatial norm in any software used for volumetric rendering, whether this is gaming, flight planning or geodata processing. But in the case of biomedical imaging, x, y and z axes also conveniently fit the “sagittal”, “coronal” and “axial” planes that were established in anatomical science in the 19th century.[10] The slices have been made to fit the fiction of medicine as seamlessly, as they have been made to fit the fiction of computation.

Extrapolated along probable axis and obediently registered to the Euclidean perspective, the slices are now ready to be rendered as high-res three dimensional volumes. Two common practices from across the industrial continuum of volumetric imaging are combined for this operation: Ray-tracing and image segmentation. Ray-tracing considers each pixel in each slice as the point of intersection with a ray of light, as if it was projected from a simulated eye and then encountered as a virtual object. “Imaging” enters the picture only at the moment of rendering, when the ray-tracing algorithm re-inserts the re-assuring presences of both ocularity and a virtual internal sun. Ray-tracing is a form of algorithmic drawing which makes objects appear on the scene by projecting lines that originate from a single vantage point. It means that every time a volume is rendered, ray-tracing performs Dürer’s enlightenment classic, Artist drawing a nude with perspective device.[11] Ray-tracing literally inverses the centralized god-like “vision” of the renaissance artist and turns it into an act of creation.

Image segmentation is the so-called non-invasive digital replacement of dissection. It starts at the boundaries rendered on each slice, assuming that a continuous light area surrounded by a darker one is indexical of the presence of coherent materiality; difference on the other hand signals a border between inside and outside. With the help of partially automatic edge detection algorithms, contrasted areas are demarcated and can subsequently be transformed into synthetic surfaces with the help of a computer graphics algorithm such as Marching Cubes. The resulting mesh- or polygon model can be rendered as continuous three dimensional volumes with unambiguous borders.[12] What is important here is that the doings and happenings of tomography literally make invisible insides visible.

From the very beginning of the tomographic process there has been an entanglement at work between computation and anatomy.[13] For a computer scientist, segmentation is a set of standard techniques used in the field of Computer Vision to algorithmically discern useful bits and pieces of images. When anatomist use the same term, they refer to the process of cutting one part of an organism from another. For radiologists, segmentation means visually discerning anatomical parts. In computer tomography, traditions of math, computation, perspective and anatomy join forces to perform exclusionary boundaries together, identifying tissue types at the level of single pixels. In the process, invisible insides become readable and eventually writable for further processing. Cut along all-too-probable sets of gestures, dependent on assumptions of medical truth, indexality and profit, slices have collaborated in the transformation of so-called bodies into stable, clearly demarcated volumes that can be operated upon. The making visible that tomography does is the result of a series of generative re-renderings that should be considered as operative themselves.[14] Tomography re-presents matter-conglomerates as continuous, stable entities and contributes strongly to the establishment of coherent materiality and humanness-as-individual-oneness. These picturings create powerful political fictions; imaginations and inventions that provoke the technocratic and scientific truth of so-called bodies.

The processual quantification of matter under such efficient regimes produces predictable outcomes, oriented by industrial concerns that are aligned with pre-established decisions on what counts as pathology or exploitation. What is at stake here is how probable sights of the no-longer-invisible are being framed. So, what implications would it have to let go of the probable, and to try some other ways of making invisible insides visible? What would be an intersectional operation that disobeys anthropo-euro-andro-capable projections? Or: how to otherwise reclaim the worlding of these possible insides?

"Representative CT slices of patient MA (top row) and T1 MRI slices of patient JF (bottom row)" in Leon Y. Deouell, Diana Deutsch, Donatella Scabini, Nachum Soroker and Robert T. Knight, “No disillusions in auditory extinction: perceiving a melody comprised of unperceived notes”, Frontiers in Human Neuroscience 2, no. 1: 15 (March 2008)
Albrecht Dürer, “Artist drawing a nude with perspective device”, 1525
Basic image registration in Slicer v4.10.2 (screenshot)

2. Slicer

In which we meet Slicer, and its collision with trans*feminist urgencies.

Feminist critical analysis of representation has been helpful in formulating a response to the kind of worlds that slices produce. But by persistently asking questions like: who sees, who is seen, and who is allowed to participate in the closed circuit of “seeing”, such modes of critique too easily take the side of the individual subject. Moreover, it is clear that in the context of biomedical informatics, the issue of hegemonic modes of doing is more widely distributed than the problem of the (expert) eye, as will become increasingly clear when we meet our protagonist, the software platform Slicer. It is why we are interested in working through trans*feminist concepts such as entanglement and intra-action as a way to engage with the complicated more-than-oneness that these kinds of techno-ecologies evidently put in practice.

Slicer or or 3D-Slicer is an Open Source software platform for the analysis and visualization of medical images in research environments.[15] The platform is auto-framed by its name, an explicit choice to place the work of cutting or dividing in the center; an unapologetic celebration of the geometric norm of contemporary biomedical imaging. Naming a software “Slicer” imports the cut as a naturalized gesture, justifying it as an obvious need to prepare data for scientific objectivity. Figuring the software as “slicer” (like butcher, baker, or doctor) turns it into a performative device by which the violence of that cut is delegated to the software itself. By this delegation, the software puts itself at the service of fitting the already-cut slices to multiple paradigms of straightness, to relentlessly re-render them as visually accessible volumes.[16] In such an environment, any oblique, deviating, unfinished or queer cut become hard to imagine.

Slicer evolved in the fertile space between scientific research, biomedical imaging and the industry of scanning devices. It sits comfortably in the middle of a booming industry that attempts to seamlessly integrate hardware and software, flesh, bone, radiation, economy, data-processing with the management of it all. In the clinic, such software environments are running on expensive patented radiology hardware, sold by global technology companies such as Philips, Siemens and General Electric. In the high-end commercial context of biomedical imaging, Slicer is one of the few platforms that runs independent of specific devices and can be installed on generic laptops. The software is released under an Open Source license which invites different types of users to study, use, distribute and co-develop the project and its related practices. The project is maintained by a community of medical image computing researchers that take care of technical development, documentation, versioning, testing and the publication of a continuous stream of open access papers.[17]

At several locations in- and around Slicer, users are warned that this software is not intended for clinical use.[18] The reason Slicer positions itself so persistently outside the clinic might be a liability issue but seems most of all a way to assert itself as a prototyping environment meant to service the in-between of diagnostic practice and innovative marketable products.[19] The consortium managing Slicer draws in millions worth of US medical grants every year, already for more than a decade. Even so, Slicer’s interface comes across as alarmingly amateurish, bloating the screen with a myriad of options and layers that are only vaguely reminiscent of the subdued sleekness of corresponding commercial packages. The all-over-the place impression of Slicer’s interface coincides with its coherent mission to be a prototyping rather than an actual software platform. As a result, its architecture is skeletal and its substance consists almost entirely of extensions, each developed for very different types of biomedical research. Only some of this research concerns actual software development, most of it is aimed at developing algorithms for automating tasks such as anomaly detection or organ segmentation. The ideologies and hegemonies embedded in the components of this (also) collectively-developed-software are again confirmed by the recent adoption of a BSD license which is considered to be the most “business-friendly” Open Source license around.

The development of Slicer is interwoven with two almost simultaneous genealogies of acceleration in biomedical informatics. The first is linked to the influential environment of the Artificial Intelligence labs at MIT. In the late nineties, Slicer emerged there as a tool to demonstrate the potential of intervention planning. From the start, the platform connected the arts and manners of Quantitative Imaging to early experiments in robotic surgery. This origin story binds the non-clinical environment of Slicer tightly to the invasive gestures of the computer-assisted physician.[20]

A second, even more spectacular genealogy, is Slicer’s shared history with the Visible Human Project. In the mid-nineties, as the volume of tomographic data was growing, the American Library of Science felt it necessary to publicly re-confirm the picturings with the visible insides of an actual human body, and to verify that the captured data responded to specifically mattered flesh. While the blurry black and white slices did seem to resemble anatomic structures, how to be sure that the results were actually correct?

A multi-billion dollar project was launched to materially re-enact the computational gesture of tomography onto actual flesh-and-blood bodies. The project started with the acquisition of two “volunteers”, one convicted white middle-aged male murderer, allegedly seeking repentance through donating his body to science, and a white middle-aged female, donated by her husband. Their corpses where first horizontally positioned and scanned, before being vertically stabilized in clear blue liquid, then frozen, and sewn into four pieces.[21] Each piece was mounted under a camera, and photographed in a zenithal plane before being scraped down 3 millimeter at a time, to be photographed again. The resulting color photographs where digitized, color-corrected, registered and re-rendered volumetrically in x, y, z planes. Both datasets (the MRI-data and the digitized photographs) where released semi-publicly. These two datasets, informally renamed into “Adam” and “Eve” still circulate as default reference material in biomedical imaging, among others in current versions of Slicer.[22] Names affect matter; or better said: naming is always already mattering.[23]

The mediatized process of the Visible Human Project coincided with a big push for accessible imagining software platforms that would offer fly-through 3D anatomical atlases, re-inserting Modern regimes at the intersection of computer science, biomedical science and general education.[24] The process produced the need for the development of automatic registration and segmentation algorithms such as the Insight Segmentation and Registration Toolkit (ITK), an algorithm that is at the basis of Slicer.[25]

Slicer opens a small window onto the complex and hypercomputational world of biomedical imaging and the way software creates the matter-cultural conditions of possibility that render so-called bodies volumetrically present. It tells stories of interlocking regimes of power which discipline the body; its modes and representations are in a top-to-bottom mode. It shows how these regimes operate through a distributed and naturalized assumption of efficiency that hegemonically reproduces bodies as singular entities that need to be clear and ready in order to be “healed”. But even when we are critical of how Slicer orders both technological innovation and biovalue as an economy,[26] its licensing and positioning also create collective conditions for an affirmative cultural critique of software artifacts. We suspect that a F/LOSS environment responsibilizes its community to make sure boundaries do not sit still. Without wanting to suggest that F/LOSS itself produces the conditions for non-hegemonic imaginations, its persistent commitment to transformation is key for radical experiments, and for trans*feminist software prototyping.

“Not for clinical use”, Slicer v4.10.2 (screenshot)
Slicer logo, 2018 and 2021
Re-rendered torso including medical equipment. Ray-tracing in Slicer v4.10.2 (screenshot)
Torso of the Visible Human with a transverse section and a corresponding CT image, created with the VOXEL-MAN 3D atlas of anatomy and radiology; © VOXEL-MAN, University Medical Center Hamburg-Eppendorf, 2001,
An abundance of extensions. Slicer v4.10.2 (screenshot)

3. Slicing

Where we introduce the Modern Separation Toolkit, and the aftermath of the cut.

The act of separation is a key gesture of Modernity. The Modern Separation Toolkit (MST) contains persistent and culturally aligned modes of euro-andro-able-anthropocentric representation: taxonomy, anatomy, perspective, individual subjecthood, objectivity and many other material-semiotic moves of division. Separation is active on every level in order to isolate the part from the whole, the one from the other and to detach the object from the subject. Modern claims of truth work from the assumption that there is a necessary relation between separability, determinacy and sequentiality; between division, knowledge and representation.[27]

The disciplines of Art Theory, History of Science and the Philosophy of Perception exemplify with their individual means the particular gestures of separation in which the complexities of a particular world are haunted and caught by Modern modes to understand, name, transmit and eventually “apprehend” these worlds. If in tomography representing is a form of grasping or control, it is evident that we need to attend to the power relations that these cutting practices produce, so we don’t allow them to be completely or definitively naturalized, culturally assumed as evident or given.

The specific mode of separation in contemporary biomedical imaging is the art of computational slicing. Our protagonist Slicer is obviously exposed to and exposing various cuts:

The subjectivity cut: Subjectivity can be understood as a prerequisite for representation, as it assures the presence of a subject responsible for a particular understanding of the world. But with the emergence of Modern subjecthood, of physical and legal persona freed from their environmental attachments and charged with free will and the capacity of judgment, additional representational norms impose themselves, somehow occupying an in-between space of singular and normative subjectivity.[28] In Slicer, the subjectivity cut is activated by the default choice of volumetric rendering, a two-point perspective where lines of sight come together in a single point, that of the individual viewer. These so-called bodies are reduced to their individual matter constellations, separated from the machinery around them, movable but divorced from their specific rhythms, without attachments or complications and most important of all, with minimal agency. Being and becoming is reduced to the incontestable promise of wholeness-at-the-end-of-the-scanner’s-tunnel.

The regional cut refers to the techno-scientific phenomena of defining a Region of Interest (ROI), a location of special attention, even if it is as vast as a globe or an atlas. The regional cut supports a focus and a training of the gaze that as a result can habituate itself on a certain area, but only at the expense of not looking at another area.[29] In Slicer, the technical definition and subsequent isolation of what is called Region Of Interest operates as a computational upgrading of the decisions behind nineteenth century atlases of anatomy. This interface’s operation presents the target as a cut. It results in a visual slicing of the virtual volume, which then exposes its invisible insides by its straight incisions.

The demarcation cut relates to the way that the practice of segmentation is present in both historical and contemporary biomedical imaging. Segmentation produces absolute divisions between image areas, organs, shades of gray and bones that obediently follow the anatomical canon. It all works together to give the renderings a sense of mathematical precision and medical evidence. In a nutshell, the process allows us to engineer a non-ambiguous spatial lay-out where each tissue or anatomical structure is identified by a label and a unique color code, all based on a black and white blur. The demarcation cut subsequently cascades into The taxonomic cut by means of the hierarchical anatomical model that Slicer shares with motion-tracking software.[30]

The invasive-non-invasive cut emerged when the tomographic paradigm imposed itself over other regimes of “seeing” in the field of biomedical imaging. This crossing concept connects the search for least invasivelessness in innovative surgery, with the thread of making invisible insides visible within biomedical informatics’ research and practice. Slicer contributes to a dense constellation of techniques and technologies that are developed to cut bodies visually, but not in the flesh.

The last cut in this list is what we learned with Karen Barad to call the agential cut. They unfold a fundamental notion, that of intra-action, to give account of the constitutive onto-epistemes in apparatuses of observation. And this agential cut is fundamental for a trans*feminist approach to techno-sciences as response-ability.[31] This cut aims for a fundamental form of response-ability that is always already entangled in the production of knowledge and its apparatuses. In Slicer, we see the agential cut operating for example in the way the Open Source condition invites and expresses a mutual responsibility of users, devices, developers, algorithms, practitioners, researchers, datasets, founders, embodiments, and other involved agents.

These six cuts identify a number of agencies and their very particular distribution. Their power relations are based on aesthetic, economic and scientific paradigms which together define the tension between what is probable in the gesture of slicing, and what might be possible.

The demarcation cut: The SPL Inner Ear Atlas is based on CT scans visualized with Slicer. Open Anatomy Project. 2018,
The regional cut: Defining a region of interest enacting a straight cut. Slicer v4.10.2 (screenshot)
The invasive-non-invasive cut: In 2015, Susan Potter donated her not-so normal body and her medical history to the Virtual Human Project. “How a Woman's Donated Body Became a Digital Cadaver,” National Geographic YouTube channel, posted December 14, 2017,

4. Feature requests

Where the paradigmatic entanglement is ready to redistribute agencies.

In previous sections we moved from slice to Slicer, and then into slicing, encountering multiple entangled trans*feminist urgencies on the way. We discussed the effects of the invention of the slice and the naturalization of its geometric and stratifying paradigms. We interrogated the agencies that altogether compose complex entanglements like our protagonist, Slicer. And in the last section, we listed six different cuts, understanding the act of division as a key Modern gesture that relates knowledge to (mostly visual) representation. Now it is time to apprehend Slicer’s technicity by other means.[32]

With trans*feminist techno-sciences we have learned that it is necessary to problematize Modern regimes and the impossibilities for life they produce. And that it is possible to do so with what we have at hand. Trans*feminism challenges the ontology of humanity by questioning its separateness from social, economic, material, environmental, aesthetic and historical issues as well as from situated intersections such as race, gender, class, age, ability and species. They also invite us to test an ongoing affirmative ethics[33] in relation to the semiotic-material compositions of what we call “our worldings”. It means to put ourselves at risk by reconsidering the very notion of “us”, assuming the response-ability of being always already entangled with these techno-ecologies which we co-compose by just being-in-the-world.

Maybe Open Source platforms such as Slicer can be environments to render so-called bodies differently. Even if this software is being developed in the particularly tight hegemony of innovation-driven, biomedical research, its F/LOSS licensing conditions invites us to imagine an affirmative critique, in dialogue with the communities that develop the software. Or could the platform itself be rendered differently through disobedient takes on the body?

This text ends with a set of “feature requests” that challenge the slicedom of Slicer. It is an attempt at starting a kind of trans*feminist prototyping for an open source software platform for biomedical informatics. To technically widen the tomographic imagination, we could maybe start by:

  • Renaming the software platform to more accurately reflect the operations it performs. Some proposals: Euclidean Anatomix, Forever dissecting, The Slicest, FlashFlesh, A-clinical Suite Pro, Tomographix Toolbox, Final Cut™, Kiss cut and the sensing knife...[34]
  • Introducing multiple and relational-perspectives. Computational rendering does not need a single vantage point, nor does it need to mimic the presence of human eyes. Next to the conventional two-way and orthogonal perspective, Slicer could bring multiple-axis and non-Euclidean perspective to the foreground.[35]
  • De-centering the ocularcentrism of the renderings and re-orient representations. It is not (necessarily) about replacing vision with touch, vibrational, thermic and aural renderings although they might be less or otherwise burdened by Modern issues. We are first of all wondering about first of all collective modes of sensing and/or observation, to include multiplied modes of gathering and of processing impressions, of involving otherwise enabling renderings of data.
  • Breaking the mirage of the interface as a mirror or window on a natural outcome. There must be ways to insist that representation is never complete: in volumetric renderings, nothingness and thereness are happening at the same time. Donna Haraway: “Partiality and not universality is the condition of being heard to make rational knowledge claims.”[36]
  • De-individualizing the imagery of the oneness of humanness. The platform does not need to technically collapse multiple slices into a discrete, single volumetric object that appear out of nowhere. Katherine Hayles says “only if one thinks of the subject as an autonomous self, independent of the environment, is one likely to experience the panic of Norbert Wiener’s Cybernetics and Bernard Wolfe’s Limbo [...] when the human is seen as part of a distributed system... it is not a question of leaving the body behind but rather of extending embodied awareness in highly specific, local and material ways that would be impossible without electronic prosthesis”.[37]
  • Problematzing the processual temporality of the volumetric images; can we make sure that we do not forget that these volumes as being constructed from takes at different moments, glued into a single object?
  • Implementing Agential Regions of Interest. This is aimed at eventually liberating and freeing the slice from the Modern project. What would an a-Modern slice be, how would it behave? How to un-capture the slice from its Modern ghosts?
  • Last but not least, we propose to dedicate some of funds to the initiation of a non-dependent program that would allow users, experts and other participants in Slicer to study the Computer Vision (sic) techniques that are implemented in this software. The program should not follow the limited spectrum of probable visions of a white-washed medical research imagination.

The possible is not about a fantastical widening of the imagination, but it is a technical condition that is already happening. This is a fundamental political twist in cultural analysis and critique of what imagination is: it is actually a technical thing. Imagination depends on the devices we collectively use, or that allow our lives to be used by. The devices we collectively use depend on that imagination. This dependency has always been and will always be mutual. When we assume this condition, then what would response-able imagery entail?

Lynn Randolph, “Immeasurable Result”, oil on masonite, 1994. Included in Donna J. Haraway, Modest_Witness@Second_Millennium. FemaleMan©_Meets_OncoMouse™. Feminism and Technoscience, Originally published in 1997.


  1. We apply the formula trans*feminist in order to convoke all necessary intersectional and intrasectional aspects around that star (*).
  2. Computer Tomography (CT) uses multiple x-ray-exposures; Positron-Emission Tomography (PET) reads from radioactive tracers that a subject has swallowed or was injected with and Magnetic Resonance Imaging (MRI) uses strong magnets and then measures the difference in speed between activation and dis-activation of atoms.
  3. Lorraine Daston, and Peter Galison, “The image of objectivity,” Representations, No. 40, Special Issue: Seeing Science (Autumn, 1992): 106.
  4. In 1917, Austrian mathematician Johann Radon introduced the Radon transform, a formula that fifty years later Sir Godfrey Hounsfield would combine with a quantitative scale for radiodensity, the Hounsfield unit (HU), to reverse-calculate images from density projection data in the CT-scanner that he invented.
  5. In 2017 circa 13.000 CT-scanners in European hospitals performed 80 million scans per year. See: “Healthcare resource statistics – technical resources and medical technology Statistics Explained,” Eurostat, 2019,
  6. See: “Item 074: The Continuum,” The Possible Bodies Inventory, 2017.
  7. CT-scanners are not non-invasive at all since they use x-rays that carry a risk of developmental problems and cancer. This triggered for example Image Gently, a campaign to be more careful with radiation especially when used on children.
  8. Sara Ahmed, Queer Phenomenology, Orientations, Objects, Others (Durham: Duke University Press, 2006), 70.
  9. Euclidian geometry relies among others on the parallel postulate: “if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which the angles are less than two right angles.” “Euclidean Geometry,” Wikipedia, accessed October 20, 2021,
  10. “Through the dissection and analysis of the body’s organisation, anatomy works to suspend any distinction between surface and depth, interior and exterior, endosoma and exosoma. It ideally makes all organs equally available to instrumental address and calibration, forms of engineering and assemblage with other machine complexes.” Catherine Waldby, The Visible Human Project: Informatic Bodies and Posthuman Medicine (Milton Park: Routledge, 2000), 51.
  11. “The woman lies comfortably relaxed; the artist sits upright, rigidly constrained by his fixed position. The woman knows that she is seen; the artist is blinded by his viewing apparatus, deluded by his fantasy of objectivity. The draftsman’s need to order visually and to distance himself from that which he sees suggests a futile attempt to protect himself from what he would (not) see. Yet the cloth draped between the woman’s legs is not protection enough; neither the viewing device nor the screen can delineate or contain his desire. The perspective painter is transfixed in this moment, paralyzed, unable to capture the sight that encloses him. Enclosing us as well, Dürer’s work draws our alarm.” Barbara Freedman, Staging the Gaze: Postmodernism, Psychoanalysis, and Shakespearean Comedy (Ithica: Cornell University Press, 1991), 2.
  12. W.E. Lorensen and Harvey Cline, “Marching cubes: A high resolution 3d surface construction algorithm,” ACM Computer Graphics 21 (1987): 163–169.
  13. See Karen Barad, “Getting Real: Technoscientific practices and the materialization of reality,” in: Meeting the Universe Halfway, (Durham: Duke University Press, 2007), 189-222.
  14. Aud Sissel Hoel, and Frank Lindseth, “Differential Interventions: Images as Operative Tools,” in Photomediations: A Reader, eds. Kamila Kuc and Joanna Zylinska (Open Humanities Press, 2016), 177-183.
  15. Slicer documentation, download and forum pages each describe its main purpose in slightly different ways: “an open source software platform for medical image informatics, image processing, and three-dimensional visualization.” “Slicer, or 3D Slicer, is a free, open source software package for visualization and image analysis.” “3D Slicer (“Slicer”) is an open source, extensible software platform for image visualization and analysis. Slicer has a large community of users in medical imaging and surgical navigation, and is also used in fields such as astronomy, paleontology, and 3D printing.” “a software platform for the analysis (including registration and interactive segmentation) and visualization (including volume rendering) of medical images and for research in image guided therapy,” All URLs accessed July 1, 2021.
  16. Waldby, The Visible Human Project, 34.
  17. The Slicer publication database hosted by the Surgical Planning Laboratory currently contains 552 publications,
  18. When launching Slicer, a pop-up appears: “This software is not intended for clinical use”. In the main interface we also find “This software has been designed for research purposes only and has not been reviewed or approved by the Food and Drug Administration, or by any other agency.” In addition, the software license stipulates in capital letters that “YOU ACKNOWLEDGE AND AGREE THAT CLINICAL APPLICATIONS ARE NEITHER RECOMMENDED NOR ADVISED,” accessed October 1, 2021,
  19. Slicer positions itself as a prototyping environment in-between diagnostic practice and innovative marketable products, and “facilitates translation and evaluation of the new quantitative methods by allowing the biomedical researcher to focus on the implementation of the algorithm, and providing abstractions for the common tasks of data communication, visualization and user interface development.” Andriy Fedorov et al., “3D Slicer as an image computing platform for the Quantitative Imaging Network,” Magnetic resonance imaging vol. 30, no. 9 (2012): 1323-41.
  20. Tina Kapur et al. “Increasing the impact of medical image computing using community-based open-access hackathons: The NA-MIC and 3D Slicer experience,” Medical Image Analysis 33 (2016): 176-180.
  21. “The term ‘cut’ is a bit of a misnomer, yet it is used to describe the process of grinding away the top surface of a specimen at regular intervals. The term ‘slice,’ also a misnomer, refers to the revealed surface of the specimen to be photographed; the process of grinding the surface away is entirely destructive to the specimen and leaves no usable or preservable ‘slice’ of the cadaver.” “The Visible Human Project,” Wikipedia, accessed October 20, 2021,
  22. Naming is a strongly politicized representational technique. See also Paul B Preciado, Testo Junkie: Sex, Drugs, and Biopolitics in the Pharmacopornographic Era (New York: Feminist Press, 2013) for a discussion of the theological-patriarchal regime of the biomedical field.
  23. See Ursula K. Le Guin, “She unnames them,” or “Item 059: Anarcha’s Gland,” The Possible Bodies Invenotory, for an account of the attempt by tech-feminist group Pechblenda to rename anatomy in an attempt to decolonize bodies.
  24. “The Visible Human Project data sets are designed to serve as a common reference point for the study of human anatomy, as a set of common public domain data for testing medical imaging algorithms, and as a test bed and model for the construction of image libraries that can be accessed through networks.” “Programs and services fiscal year 2000,” National Institutes of Health, National Library of Medicine, 2000,
  25. “Insight Segmentation and Registration Toolkit,” accessed October 1, 2021,
  26. “Technics can intensify and multiply force and forms of vitality by ordering it as an economy, a calculable and hierarchical system of value – exist in circulation and disctribution, can function in other economies.” Waldby, The Visible Human Project, 33.
  27. As Rosi Braidotti notes, “Modern science is the triumph of the scopic drive as a gesture of epistemological domination and control: to make visible the invisible, to visualise the secrets of nature. Biosciences achieve their aims by making the embodied subject visible and intelligible according to the principles of scientific representation. In turn this implies that the body can be split into a variety of organs, each of which can be analyzed and represented.” Rosi Braidotti, Nomadic Subjects: Embodiment and Sexual Difference in Contemporary Feminist Theory (New York: Columbia University Press, 2011), 196.
  28. Daston, and Galison, “The image of objectivity,” 106.
  29. “[W]hat was not new to nineteenth-century atlases was the dictum “truth to nature”: there is no atlas in any field that does not pique itself on its accuracy, on its fidelity to fact. But in order to decide whether an atlas picture is an accurate rendering of nature, the atlas maker must first decide what nature is. All atlas makers must solve the problem of choice: which objects should be presented as the standard phenomena of the discipline, and from which viewpoint? In the late nineteenth century, these choices triggered a crisis of anxiety and denial, for they seemed invitations to subjectivity.” Daston, and Galison, “The image of objectivity,” 86.
  30. The model for anatomical data in Slicer resembles the crude cascading hierarchies used in basic motion tracking software.
  31. “We are responsible for the world within which we live not because it is an arbitrary construction of our choosing, but because it is sedimented out of particular practices that we have a role in shaping. and ‘The crucial point is that the apparatus enacts an agential cut – a resolution of the ontological indeterminacy – within the phenomenon, and agential separability – the agentially enacted material condition of exteriority-within-phenomena – provides the condition for the possibility of objectivity. This agential cut also enacts a local causal structure in the marking of the measuring instrument (effect) by the measured object (cause), where ‘local’ means within the phenomenon.” Karen Barad, “Getting Real,” 390 & 175.
  32. Hoel, “Differential Interventions: Images as Operative Tools,” 177-183.
  33. Rosi Braidotti, “Affirmative Ethics, Posthuman Subjectivity, and Intimate Scholarship: a Conversation with Rosi Braidotti”, in “Decentering the Researcher in Intimate Scholarship”, Advances in Research on Teaching, no. 31, Emerald Publishing Limited, 2018, 179-188.
  34. “Only our starfish can save us, by regrowing whatever grooms like me cut out of them. Grandma Chan Ling invented the kiss cut, the repair job — what do you say? The fix, the patch. The first starfish gave her liver, her kidneys, and, at last, her red-hot heart to the first doubler. And so it was, in the beginning.” Larissa Lai, The Tiger Flu, 2019, or see: Item 116: Kiss cut and the sensing knife, The Possible Bodies inventory, 2020.
  35. Slicer does offer a second perspective rendering, namely “orthographic perspective” (straight-extreme).
  36. Donna Haraway, “Situated Knowledges: The Science Question in Feminism and the Privilege of Partial Perspective,” Feminist Studies 14, no.3 (1998): 589.
  37. N. Katherine Hayles, “What does it mean to be posthuman?,” in The New Media and Cybercultures Anthology, ed. Pramod K. Nayar (Hoboken: Wiley-Blackwell, 1988), 25.

Thank you Antye Guenther, Martino Morandi, Zoumana Meite and Dennis Pohl for valuable feedback.

A shorter version of this text was originally published as: Rocha, J. and Snelting, F., "La imaginación invasiva y sus cortes agenciales". Utopía. Revista de Crítica Cultural (April-June 2019)