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Calculating the Measurements of Objects

Digitome is capable of accurate measurement down to the order of microns given a small focal spot size and low pixel depth for a digital image plate, typical conditions for high-resolution digital radiographs. This video demonstrates how Digitome measures objects in an exam; the objects used have well-known sizes to test the software’s accuracy.

The first sample object is a wooden block with two screws and a nail. The screws have been drilled into the block on the same face about half an inch apart. The nail has been placed into the block at the center of an adjacent face of the block so that it is orthogonal to and in between the screws. The most interesting aspects of this composite are its screw threads, which have different densities. One of the screws has about 24 threads/inch while the other has about 32 threads/inch (manufacturer’s quantities, McMaster Carr). With Digitome, we are able to discern the thread patterns and measure about 24 threads/inch and 32 threads/inch, respectively.

The second object is made of two ruby spheres used in fiber-optic cables placed in contact with each other on a flat plane. The spheres in fiber-optic cables must be accurately made to precisely transmit information throughout the cable. Thus, the two spheres have been made with an uncertainty in diameter only the level of microns. Digitome effectively measures a diameter that has only a 1.29% error compared to the manufacturer value.

In contrast to Computed Axial Tomography exams, Digitome exams do not have to interpolate between slices and therefore (theoretically) contain all of the object information in one exam. So accurate measurements made in the software can be used to measure any aspect of an object that is detectable through x-ray imaging.

These measurements were carried out with a tungsten x-ray source with a spot size of 0.5 mm and an amorphous silicon digital image plate with a pixel depth of 127 microns.

 

Smithsonian: Davidson College and the 3D X-ray Digitome Technology

Davidson College, a four-year liberal arts college located in Davidson, NC, is using a flexible and portable technology from Digitome Corporation for taking three-dimensional x-radiographic examinations of various archaeological objects. The Digitome software constructs a volumetric display of an imaged object using multiple images of the object from different perspectives. Typically, a 3D exam is constructed from around eight images of the object.

This technology has potential applications in art and object conservation, archaeology, and other fields requiring non-destructive testing. Over the summer of 2014, Dr. Dan Boye (Professor of Physics, Davidson College) and I, (Ryan Kozlowski, Davidson College class of 2016) applied the Digitome technology to archaeological artifacts from the Queen Anne’s Revenge (QAR), the flagship of infamous Blackbeard the Pirate. This research was funded by the Davidson Research Initiative.  The QAR Conservation Laboratory, located in Greenville, NC, is a part of the North Carolina Department of Cultural Resources (NCDCR).

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Charlotte Observer: High Tech Tackles Blackbeard’s Booty

Students in Davidson College’s physics department have been examining artifacts from a long-ago grounded ship off the North Carolina coast that state officials say was Blackbeard’s Queen Anne’s Revenge. But this isn’t a treasure hunt.

For them, the prize is in the discovery – uncovering clues about life in the early 1700s, perhaps even solidifying evidence that these are indeed pieces from Blackbeard’s ship – and in the chance to gain and share knowledge in many fields based on what they’ve learned from new technology.

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Hidden Woman Revealed in DuMond Painting

At first glance, this painting appears to be quite normal. However, on closer inspection you begin to see faint signs of another woman who has been hidden and painted over. The bottom of her skirt is starting to show under the top layer of paint near the bottom, and when you look at the painting with a slight glare (as we did in this picture) you see the ghost of a face next to the woman in profile. Who changed the composition of this painting? Why was the original woman painted over?

Older oil paintings are made with paint mixed from metals, which will show up in an x-radiograph. To investigate this mysterious woman, we took a traditional x-ray of the painting. Because we do not see the overpainted woman in the x-radiograph we believe that she was added using different paints that either do not include metals or include metals like zinc and copper which do not always appear in x-radiographs. Her face does not appear to be painted by the same hand that painted the seated man.

The x-radiograph shows that the two women have different styles of clothing, are facing different ways, and are engaged in different activities. The original woman has a lower neckline and a different style of collar, as well as a different hat. If you look at the bright dots on the x-radiograph, they line up with the pitcher on the table and the vase above the man. This leads us to believe that she is holding some type of container above the man’s glass. The original woman is closer to the man and is interacting with him, while the overpainted woman is in the background slightly behind the doorframe.

To discover more, a near infrared picture was taken that shows other aspects of the original woman. We can see her face more clearly and can tell that she is facing the man. The bottom of the pitcher she is holding is visible. We see that the man has not been changed from the original.

With x-rays and infrared radiation, we can see much more of the original painting. This new knowledge makes one wonder what the reasons behind the change are. Was the original woman the man’s wife or just a maidservant? Did the owner’s view on the role of women in general change?

­­We would like to acknowledge Professor Ruth Beeston of Davidson College Chemistry Department for directing us to this as an example of an underpainting and for her help with the infrared reflectography.

 

Non-destructive X-ray Imaging System Helps Reveal the Past

Blackbeard and the Queen Anne's Revenge

Painting of Blackbeard’s Queen Anne’s Revenge (inset: Edward Teach, better known as Blackbeard).

Blackbeard’s infamous pirate ship, The Queen Anne’s Revenge (QAR), lay lost on the ocean floor off the North Carolina coast for almost 300 years. It was discovered in 1996, but most of the relics of colonial culture aboard its decks, such as specks of gold, glass beads, firearms and brass pins, remain hidden inside a thick crust of muddy sand and shells.

With the help of the Davidson Research Initiative, Ryan Kozlowski ’16 and Professor of Physics Dan Boye hope to shed some light on those items by using their Digitome non-destructive x-ray imaging system. Their examination of a half-dozen items from the pirate ship this summer at the N.C. Department of Cultural Resources lab located at Eastern Carolina University could add to the evidence that this was indeed Blackbeard’s ship.

“Digitome imaging can be done on a laptop,” explained Kozlowski. The configuration at Davidson consists of three main parts. A source shoots x-rays into the cabinet. The object of the examination rests inside the cabinet on a circular plastic plate attached to the image plate. The object and image plate can be tilted and the plastic plate can be rotated to record as many as 32 different perspectives of the object, though just eight views are commonly captured. The system’s proprietary software immediately assembles the different views such that any mathematically-defined contour can be viewed.

 

Three-dimensional Digitome Exam Shows Fine Details of a Pythagoras Cup

The original Pythagoras cup was designed around 500 BC to teach its users to drink in moderation. If liquid is filled into the cup above a specific height, it all completely funnels out of a hole in the bottom of the cup and onto the drinker’s lap. A three-dimensional radiographic exam of a modern Chinese Pythagoras cup was taken to reveal the simple structure of the cup that allows the siphoning mechanism to occur. Though design or object material changes across cultures and time, the functionality of the Pythagoras cup remains the same.

The cup has a neck at its center with an opening at its base. Inside of the neck, which is sealed off at the top, is an inner tube that is open at the top (within the neck) and the bottom (visibly seen on cup surface). As a user pours fluid into the cup, the fluid fills in the neck to the same height as the fluid in the open, visible area of the cup. When a portion of the fluid in the neck overflows and begins to pour down the inner tube by gravity, the remainder of the fluid in the entire cup follows the flow up through the neck and down the inner tube because of reduced pressure and an overall decrease in the gravitational potential energy of the system. The Pythagoras cup is really just a self-priming siphon.

The three-dimensional exam reveals that the inner tube is at a height of approximately 1.20 inches from the bottom layer of the cup. It affirms that the dragon’s head is sealed off from the neck and demonstrates the effectiveness of the Digitome software in accurately measuring object parts and picking up on fine details like the horns of the dragon or the opening in the back of its neck. This video shows a scan upward through the object—Digitome can produce a “stack” of images for an object, and the user can export the stack to commercial software that can then produce a 3-dimensional surface view, as displayed at the end of the video.

 

Davidson Will Lead in Exploring Scientific and Humanistic Capabilities of New 3D Imaging System

Philip Wall and Professor Boye

Phillip Wall ’14 and Professor of Physics Dan Boye.

View a video of a Digitome scan.

Davidson physics students plowed new scientific ground in 1896 when they took the first X-ray images on American soil. Contemporary Davidson physicists now have a similarly momentous opportunity. The department has recently become the first non-governmental entity in the country to acquire a revolutionary Digitome VXI-500Fx non-destructive imaging system. The system combines a series of conventional two-dimensional x-ray images taken from various angles around an object into a three-dimensional “volumetric” screen image that can be turned, rotated and probed from any angle or plane.

Images of a Digitome scan are recorded on an 8-inch by 10-inch CCD plate rather than a piece of film. The image is therefore recorded instantly as a computer file rather than being projected onto film that must be developed.

The Digitome’s unique ability to create a three-dimensional image of an object led Professor of Physics Dan Boye to hail the system as a “cross-disciplinary game changer” for Davidson. He said, “We believe we can apply the Digitome to help understand topics of interest in the humanities and social sciences.”

In his proposal to purchase the system, Boye wrote, “It would foster trans-disciplinary learning and research throughout the college by partnering physics faculty and students with teaching and research efforts in other departments and programs.”

For instance, Boye envisions its use by the art department to examine layers of paintings which may have been covered with other layers. Archeologists could examine mummies inside sarcophagi. Book conservators could view intricate binding techniques of rare works without having to open them.

The Digitome company has already documented several uses in the arts. A Digitome examination of a music stand owned by Mozart revealed that pieces were screwed together with reverse threading. The emperor of Japan requested a Digitome examination of an urn to see if the handle had been modified. A Digitome exam found that the general absence of cracks in the intricate enamel of a Ming vase at the Los Angeles County Museum of Art resulted from expansion joints on the inside surface. An examination of a jet engine turbine blade revealed cracks that could have been dangerous.

Digitome reveals inside of an iPod

A Digitome image reveals the internal components of an iPod.

How It Works

The Digitome machine consists of three main parts. A generator shoots x-rays downward into a four-foot tall lead-lined cabinet. The object of the examination rests inside the cabinet on a circular plastic plate attached to the CCD plate. The CCD plate can be tilted and the plastic plate can be rotated to record as many as 32 different views of the object. The system’s proprietary software immediately assembles the different views such that any 2D mathematically-defined contour can be viewed.

The system’s portability, scalability, rapid results and ability to measure any aspect of tested subjects make it comparable if not superior to other techniques such as computed tomography (CT), positron electron tomography (PET), ultrasound and magnetic resonance imaging (MRI).

Though the Digitome exams are most easily accomplished in the cabinet, the mounting fixture and image plate are removable and easily portable to remote locations such as a museum for off-site examination of fragile or valuable pieces.

Physics and math major Phillip Wall ’14 is spending the summer in the lab learning the Digitome system and writing user protocols. He said, “More and more I’m realizing this is a pretty big deal for Davidson, and it’s fun to blaze a trail as the first student operator.”

In one of his tests, Wall examined his iPod, revealing its components stacked on top of each other inside the case. His examination of a baboon’s skull obtained from the biology department revealed non-emergent teeth concealed in the jawbone. He conducted an exam of a Chinese “cadogan” style wine pot with no lid which revealed the interior hollow stem that allows it to pour without spilling. He examined a closed prayer locket from the college archives to determine whether it concealed a scroll.

Wall operates sliders on the screen to control image contrast and resolution, and movement around and through the sample through image rotation, tilt and zoom.

His examination of a common gaming die vividly displayed the system’s capabilities. The captured three-dimensional image began on the one-dot side of the cube. Wall then moved straight through the die to reveal the six dots on the opposite side. Through rotation and controlled movement, he revealed all the other sides of the die. “It’s a graphic way to demonstrate its volumetric capability,” Wall said.

Boye plans to enlist future students to learn the system as well so that they can handle requests from other departments and external agents. The techniques and skills they learn in operating the machine will prepare them to operate almost any radiographic system.

Since he has no professional training in radiography, Boye is also learning the system along with Wall. To make the most of the department’s new resource, Boye has joined the American Society of Nondestructive Testing, and will attend its digital imaging meeting later this month.

Digitome reveals teeth

This Digitome image reveals teeth inside the jawbones of a monkey skeleton.

Digitome’s Local Connection

Boye is also enjoying the new collaboration with an outside business. Digitome is a tightly held 30-year-old corporation that has supplied imaging devices almost exclusively to the defense and aerospace industries. NASA has used its imaging products to detect cracks inside a space shuttle surface forewing, and the armed forces have examined exploded IED pieces to gain clues about their origins.

One stage in the development of the Digitome company took place in Davidson where it was housed in the Industrial Dynamics building off Griffith Street. The company is led by CEO Donald Twyman, who currently lives in the Davidson area. Twyman approached Davidson’s physics department earlier this year as a means for exploring new applications for the Digitome. Impressed with the physics program and its personnel, Twyman helped arrange purchase of the machine by the college, and created a proprietary license for its software.

Twyman has been a regular visitor to the physics lab, helping Boye and Wall learn to operate the system and explore new functionalities. Boye explained, “They want to see uses that may emerge when they put the Digitome system in the hands of liberal arts students rather than engineers. This is a great opportunity for us in applied physics. Who knows? We might even discover new uses for it that could yield patents and generate revenue for the college. It’s an exciting step for us not only in partnering with other departments inside the college, but with an outside, private business.”

Original article written by Bill Giduz

Digitome Exam of an Alaska Quarter

Two-dimensional x-radiography is often sufficient for looking at simple, relatively flat objects. But what happens when an object has multiple layers of information or overlapping parts? A coin with two faces is an example of such an object—a two-dimensional radiograph allows the viewer to pick up certain details of each face of the coin, but these details inevitably overlap. Similar issues may occur for other objects, such as a painting with multiple layers or a complex circuit board.

A Digitome exam was taken of an Alaska quarter to see if the two separate faces could be isolated, and it was successful. One distinct layer of the coin scan reveals the grizzly bear springing out of a rushing river and biting his catch—a salmon. Moving down through the coin, the face of George Washington is clear, but analysis of the words reveals that the radiographic image face is actually a mirror image of the real face! The coin had been placed with Washington’s face down on the image plate, so its shadow was flipped. (Imagine an ink stamp or the imprint of a boot in the mud.) In the video, after scanning, the coin is manually rotated and flipped by video software for ease of viewing.

The characters (text and numbers) on each face are visible albeit not completely clear. The designs on the coin are made through pressing blank copper-nickel alloy with imprints that outline the images and characters; the result is that any pressed coin has varying thicknesses and therefore different levels of attenuation (absorption or scatter of x-rays) across the coin. Characters are areas of greater thickness and Digitome distinguishes the changes in thickness on both faces from one another. Still, the characters on the quarter are somewhat difficult to resolve because of the limitations of resolution. Resolution is determined by the image plate used, the position of the object relative to the source and detector, and, in this instance, the size of the letters (on the order of millimeters).

 

New Physics Imaging Device Will Help Reveal the Past

Digitome team, professor and three students

The Digitome team includes (front) Phillip Wall ’14, (back) professor Dan Boye, Rebecca Garner ’16 and Ryan Kozlowski ’16.

Blackbeard’s infamous pirate ship, The Queen Anne’s Revenge (QAR), lay lost on the ocean floor off the North Carolina coast for almost 300 years. It was discovered in 1996, but most of the relics of colonial culture aboard its decks, such as specks of gold, glass beads, firearms and brass pins, remain hidden inside a thick crust of muddy sand and shells.

With the help of the Davidson Research Initiative, Ryan Kozlowski ’16 and Professor of Physics Dan Boye hope to shed some light on those items by using their Digitome non-destructive x-ray imaging system. Their examination of a half-dozen items from the pirate ship this month at the N.C. Department of Cultural Resources lab located at Eastern Carolina University could add to the evidence that this was indeed Blackbeard’s ship.

The NC Cultural Resources department’s QAR team has thus far retrieved, catalogued and stored 3,000 encrusted objects from the wreck. But the two-dimensional film x-rays of those objects they produce are not as revealing and helpful as a Digitome inspection can be.

The Digitome system, which was purchased by the Davidson physics department, gives students access to a cutting-edge imaging device. Professor Boye, who is managing the project, said the system has application in many liberal arts disciplines.

“Digitome Corporation wanted to see uses that may emerge when they put the Digitome system in the hands of liberal arts students rather than engineers,” Boye explained. “This is a great opportunity for us in applied physics research.”

Game Changer

The way in which the Digitome system creates a three-dimensional image of an object leads Boye to hail it as a “cross-disciplinary game changer” for Davidson. He said, “We believe we can apply Digitome to help understand topics of interest in the humanities and social sciences as well as the sciences.”

During the past school year two students learned the system and explored applications throughout the curriculum. Phillip Wall ’14 created an examination of a common gaming die that vividly displayed the system’s capabilities. The captured three-dimensional image began on the one-dot side of the cube. Wall then moved straight through the die until the six dots on the opposite side came into view on the screen. Through rotation and controlled movement, he revealed all the other sides of the die. “It’s a graphic way to demonstrate its volumetric capability,” Wall said.

Student researchers have experimented with a variety of objects in honing their examination techniques, including skulls of a baboon, a wolverine, a snapping turtle and a python. Examination of a novel Chinese ceramic wine cup revealed the internal structure of a self-priming siphon. An examination of a brittle prayer pouch from the library verified the existence of a scroll inside without having to open it.

Steven Keller ’14 provided support for a project by students in an animal physiology class taught by Professor of Biology Michael Dorcas. Keller examined the rate of mouse digestion when corn snakes are kept at different environmental temperatures, and he also examined flawed welds in steel plates.

Two other students are conducting Digitome research this summer. In preparation for work at the QAR Lab, Kozlowski has been creating high-resolution images of the nearly flat surface of coins, even when encased in over an inch of plaster. Rebecca Garner ’16 is making paintings with Old World pigments to see how the system might be used to reveal artistic techniques, modifications and even underpaintings.

Three Main Parts

“Digitome imaging can be done on a laptop,” explained Kozlowski ’15. The configuration at Davidson consists of three main parts. A source shoots x-rays into the cabinet. The object of the examination rests inside the cabinet on a circular plastic plate attached to the image plate. The object and image plate can be tilted and the plastic plate can be rotated to record as many as 32 different perspectives of the object, though just eight views are commonly captured. The system’s proprietary software immediately assembles the different views such that any mathematically-defined contour can be viewed.

Though the Digitome exams are most easily accomplished in the cabinet, the mounting fixture and image plate are removable and easily portable to remote locations such as a museum for off-site examination of fragile or valuable pieces. To test its portability, the team twice this spring took the system to a room-sized x-ray vault at Central Piedmont Community College. It allowed them to do a test examination with a moveable x-ray source, whereas in the past they employed a fixed source and moved the object. East Carolina University’s QAR Lab, where the Davidson team is working, is also room-sized.

Davidson students are a crucial part of the Digitome project because learning to properly use the system requires some training and experimentation, according to Kozlowski. “There are adjustments to make in frame rate, frame count, beam energy, gamma, contrast and histogram,” he explained. “Another challenge is learning to view with your mind’s eye an image in three dimensions rather than the usual two.”

Boye will continue to enlist students to learn the system so they can handle requests from other departments and external agents. He noted that the experience and skills they develop through using Digitome prepares them well for work with almost any imaging system, and gives them valuable experience for careers in a wide variety of fields. Last year’s student assistants prove that point. Steven Keller ’14 has been accepted into the UVA medical school for studies in biophysics and biomedical imaging, and Phillip Wall ’14 will be pursuing graduate work in medical physics at LSU.

Agreement Breaks Ground

Digitome Corporation is a tightly held 30-year-old business that has, until now, supplied its imaging devices almost exclusively to the defense industry and government-related organizations. One of their exams was instrumental in determining the cause of the Space Shuttle Columbia disaster, and led to the solution for the return to space after the grounding of the shuttle missions. Other Digitome Corporation examinations revealed that a music stand owned by Mozart had pieces screwed together with reverse threading, that the handle of an invaluable Japanese national treasure had been modified, and that the general absence of cracks in the intricate enamel of a Ming vase resulted from expansion joints on the inside surface. An examination of a jet engine turbine blade revealed cracks that could have been dangerous.

In a unique agreement facilitated by Digitome Corporation, the college has entered into a licensing agreement to sell Digitome systems and software to educational institutions and museums. Davidson will receive a percentage of the revenue on the sale. This is the first time Davidson has tried to set up a self-supporting, profitable entity.

“It’s a new venture for Davidson,” said Boye. “We received startup funds from the college to get the project rolling, but we’re expecting to be self-supporting soon. Revenues we generate will go back into the project, supporting student employment and training, equipment procurement, marketing and presentation of our findings at professional meetings.”

The system’s portability, cost, scalability, rapid results and ability to measure any aspect of tested subjects make it comparable if not superior to other imaging techniques such as computed tomography (CT), positron electron tomography (PET), ultrasound and magnetic resonance imaging (MRI).

Boye is inviting about two dozen museum curators and academicians to attend the first comprehensive Digitome marketing showcase, which will occur soon in Washington, D.C. Following that kickoff event, the system will be promoted online, and with demonstrations at Davidson and other locations.

Article written by Bill Giduz

Unveiling the Hollow Interior and Measurements of a Geode

Geodes are hollow, closed shells made of igneous or sedimentary rock. They generally form in cooling lava or in sedimentary geological structures over several thousand years. Though the mechanisms of void formation differ, the same process occurs in time for all geodes: water-carrying minerals, usually calcite (CaCO3), seeps into the microscopic pores of the shell and accumulate the inner lining that, in the final product, is a visually pleasing crystalline structure,.

Since these rocks are closed surfaces, the only practical ways to view the inner crystals are to break them or to use a form of imaging that makes use of light outside of the visible range like x-radiography. A two-dimensional x-ray image will be able to detect that the rock is hollow, but it will not necessarily include information about the varying thickness of the shell or the shape of the crystal lining. A Digitome volumetric exam, however, is able to detect the contour of the void within the rock in a non-destructive manner.

The elemental make-up and thinness of the geode shown in the video allow for easy penetration of x-rays that are relatively low in energy. The quartz is mainly silicon dioxide and the crystal lining’s most absorptive element is calcium, with an atomic number of 20. The exam in the video was taken with an x-ray beam of 80 kVp; metallic elements like iron, of atomic number 26, often require more energy for adequate penetration. Since calcium composes much of the geode, this material is a good model for concretions that would be found on the ocean floor in underwater archaeology excavations. In particular, the geode shown in the video was volumetrically examined to prepare for taking three-dimensional x-radiography exams of artifacts in concretions from the Queen Anne’s Revenge.

Scanning upward through the geode, it is evident that much of the rock is indeed hollow. Areas of particularly low or high thicknesses are identifiable through the exam and can be accurately located on the actual geode. Because of this, one could carefully break open the geode or open a small hole by accessing an area of weakness found in the 3D exam. This potentially provides the opportunity for a cleaner cut of the rock for museum display, personal use, or commercial purposes.

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