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Figure 9.1A A Polaroid image of Jeremy Bentham's left hand, demonstrating the pins, plates, and wire used to articulate the skeleton. Note the broken plate (arrow) that formed the joint between the proximal and middle phalange of the fifth digit.

Figure 9.1B an AP projection of the left foot, showing that most of the wires (arrows) across the metatarsal phalangeal joints were broken.

Radiographs were then taken of Jeremy Bentham's mummified head. Although otherwise unremarkable, the radiographs clearly demonstrated a pair of interesting artifacts, the glass eyes that Bentham used to carry around in his pocket prior to his death (Figure 9.4A). Because of the superimposition of the eyes on the initial lateral radiograph, an oblique projection was taken, making it easier to assess the glass eyes (Figure 9.4B). Endoscopic images demonstrated the packing material used in the mummified head's cheeks to maintain a full, healthful appearance. When the endoscope was introduced into the interior of the cranial vault, we were surprised to find what appeared to be seeds adhering to the inside of the skull (Figure 9.5). Several seeds were removed under endoscopic guidance and sent for analysis. The seeds were identified as mustard seeds. In the era that Bentham died, cranial volume was thought to be a measure of intellectual capacity. Bentham's cranial capacity was measured by pouring mustard seeds into the cranial vault, then quantifying that volume by pouring the seeds from the cranium into a volumetric container. Bentham surely must have approved, or even suggested, such a measure as a further demonstration of the value of scientific study of deceased bodies and to further advance the cause of Utilitarianism.

Figure 9.2 composite Polaroid images showing the hardware used to articulate the pelvis, spine, and right hip.

Figure 9.3 Endoscopic images showing various hardware used to rearticulate the skeleton of Jeremy Bentham. The bolts and nuts appear to be in reasonable condition with no critical oxidation. The image in the lower right shows a wire used to hold the individual vertebrae together as seen from the vertebral canal.

Figure 9.3 Endoscopic images showing various hardware used to rearticulate the skeleton of Jeremy Bentham. The bolts and nuts appear to be in reasonable condition with no critical oxidation. The image in the lower right shows a wire used to hold the individual vertebrae together as seen from the vertebral canal.

Figure 9.4A Lateral Polaroid radiograph of the anterior portion of the skull revealed the glass eyes within the orbits. However, due to superimposition, the eyes were not discernible.

Figure 9.4B An oblique projection of the skull provided a more unobstructed view of the right eye (arrow).

Figure 9.5 Endoscopic images showing wide distribution and relative size of mustard seeds within the endocranial vault of Jeremy Bentham's mummified head.

Case #2: The Conservation and Construction Features of the slater Museum Plaster Cast Collection

For more than 100 years the Slater Museum, located on the campus of Norwich Free Academy in Norwich, Connecticut, has displayed and interpreted the best examples of fine and decorative art, representing a broad range of world cultures of the Americas, Asia, Europe, and Africa. Dedicated in 1888 and housed in a stunning Romanesque Revival building, the Slater's local collection represents 300 years of Norwich history. Featured are 18th through 20th century American paintings and decorative arts, including contemporary Connecticut crafts; 17th through 19th century European paintings and decorative arts; African and Oceanic sculpture; Native American objects; and a group of plaster casts representing Egyptian, Archaic, Greek, Roman, and Renaissance sculpture. The casts are a magnificent sight, with some standing 10 m high or more in a beautiful gallery. Henry Watson Kent, the museum's first curator, engaged Edward Robinson, curator of antiquities at the Boston Museum of Fines Arts, to select the casts. A plasterer, Giovanni Lugini, was commissioned to assemble the plaster parts into replicas of the great masterworks. To look at the casts, one would think they are the originals. Lugini was also charged with fitting the casts with fig leaves upon their completion to obscure the genitalia, a practice employed in England at the time as well.

The museum director needed to find out how the cast pieces were constructed internally, how fragile they might be, and, in the case of the plaster frescos, how they were attached to their display wall. With this information, conservation efforts and museum renovation plans could be better informed.

Figure 9.6 Radiographic instrumentation setup for the first image of the plaster cast of the standing Youth.

Three plaster casts of classical statues and three mounted casts were examined with portable radiography using conventional radiography with Polaroid photographic film and Fuji industrial CR plates to determine the assembly methods, locations of armatures within each piece, and the presence and extent of any cracks. Radiography was also employed in an attempt to ascertain the method used to mount two fixed casts on opposite sides of a display wall. However, since conventional radiographs are two-dimensional (2D) images of three-dimensional (3D) objects, videoendoscopy was necessary to delineate superimposed structures and document the manner of fixation.

Radiography proved to be very helpful in the demonstration of the various techniques used to construct these works of art. The radiographs revealed internal construction and support methods for the casts, including the Standing Youth, Dying Gaul, and the Winged Victory.

The Standing Youth may be the only piece in the museum that was not produced by Lugini. The statue was donated to the Slater by the Hartford Athenaeum and constituted the least complex imaging situation. The site to be evaluated was a crack on the left leg. Since the statue was in an erect standing position, the approach was to simply place an 8 x 10 in. (20.32 x 25.4 cm) Polaroid cassette behind the crack and rest the x-ray tube on a cart in front of the cast (Figure 9.6). The exposure at a 40 in. (101.6 cm) SID (source-to-image receptor distance) was set at 80 kVp and 16 mAs. When the film was processed, a metallic rod was noticed within the leg, extending the length of the image. To determine the length

Figure 9.7 Placement of a standard 14 x 36 in. (35.56 x 91.44 cm) cassette used to capture an image of the entire leg of the Standing Youth.

of the rod within the leg, a 14 x 36 in. (35.56 x 91.44 cm) cassette was used to image the entire leg on a single film (Figure 9.7). In order for the x-ray to cover the larger-size film, the x-ray tube was pulled back to a 72 in. (182.88 cm) SID, and the exposure was taken at 80 kVp and 5 mAs. Since conventional x-rays are 2D images of 3D objects, a second projection positioned at a 90° angle to the first film is required to gain a spatial orientation of structures. Therefore, a lateral or side projection of both legs was obtained on a single 14 x 36 in. (35.56 x 91.44 cm) cassette. Since the right and left "thighs" overlapped, the radiographic technical factors had to be increased to 86 kVp and 10 mAs.

The most challenging imaging task was that of the cast of the Winged Victory. The statue was mounted on a pedestal that was over 10 ft (3 m) above the floor and had about a 4 m wingspan. The challenge was to image each wing and its articulation with the body of the cast to determine not only how they were attached but also to ascertain the condition of those articulations. A movable scaffold was assembled to allow us to get the film close to the structures of interest and to properly position the x-ray tube. Polaroid film was used to establish the correct technical factors at a 40 in. (100 cm) SID. Because the film is only 8 x 10 in. (20 x 25 cm) and due to the fact that a tremendously long SID would be necessary to radiograph both wings, it would not have been realistic to use the small film for the entire study. However, once the Polaroid exposure settings were determined, a conversion factor could be established to enable the use of cassettes loaded with conventional radiographic

Figure 9.8 Three 14 x 17 in. (35.56 x 43.18 cm) cassettes configured to cover large sections of the Winged Victory wing.

film. Since each wing required a film area greater than 36 x 50 in. (91.24 X 127 cm), it was decided to construct a device that would accommodate multiple cassettes. After several attempts, a Foamcore® and cardboard apparatus that could support three 14 x 17 in. (35.56 x 43.18 cm) cassettes was used (Figure 9.8). Three exposures with this device positioned vertically covered the entire wing (Figure 9.9).

Figure 9.9 The constructed film holder for the Winged Victory in place.
Figure 9.10 Photograph showing the x-ray tube placement on the balcony overlooking the gallery for the initial radiographs of the Winged Victory. The centering laser is seen at the location of the wing articulation (arrow).

Although the challenge of positioning the film was resolved, the x-ray tube had to be placed so as to direct the beam at right angles to each wing. In order to create a montage of the images, it was necessary to position the tube at a distance great enough to cover the entire area without moving the tube between exposures. Within the exhibit hall of the museum was a second-floor balcony. Using the balcony, the x-ray tube was placed on a cart overlooking the statue. With the x-ray tube positioned at two locations along the balcony, it would be possible to acquire the correct angle and distance to capture each wing articulation entirely. For the right wing, the x-ray tube was at a 17 ft (5.2 m) SID, and the left was at 40 ft (12.2 m). Because the particular radiographic unit, a MinXray 100/30, was equipped with a laser-centering light, it was possible, at that great a distance, to accurately center the x-ray beam (Figure 9.10). Through trial and error, it was determined that 90 kVp was necessary to penetrate the thickness of plaster in the shoulder area. In addition, at the 40 in. (100 cm) SID, the Polaroid system required 120 mAs to produce an acceptable image. To distribute the heat load on the x-ray tube, three exposures were taken at 40 mAs with a 30 s delay between successive exposures. With that as the base technique, the inverse square law was applied to calculate exposures for the long-distance projections on the larger cassettes. In addition, the conversion factor between the Polaroid system and the conventional cassettes was applied by dividing the Polaroid exposure by 3.75. The right shoulder required a total of 800 mAs or 20 exposures at 40 mAs each. Even with a 30 s delay between exposures, the unit would have exceeded its heat load capacity and failed. The solution, devised by a student assistant, was to duct tape ice packs to either side of the x-ray tube (Figure 9.11). The left shoulder had the longer SID and required a total of 2000 mAs or 50 exposures at 40 mAs each. Figure 9.12 shows the composite x-rays created from this film holder and exposure technique.

Once the recording media was shifted from the Polaroid to the conventional radiographic film, a film-changing area became necessary. Creating a dark room in the rear of a 1994 Dodge Van initially solved the problem. A smaller version of the PVC pipe frame

Figure 9.11 Ice pack method used to keep the radiographic unit cool for the extreme exposure sequence used for the Winged Victory.
Figure 9.12 Composite of the Winged Victory radiographs.

structure previously described in Chapter 2 was established. Unfortunately, during the summer months, the temperature reached over 120°F (49°C). Later, a storage closet within the museum was converted into a light-tight space.

Although the supporting metallic rods were clearly demonstrated in each wing, the radiographs failed to reveal the position of the supporting structures in the left and right "shoulder" areas. Since it was felt that the maximum output of the x-ray tube had been reached with the available image receptors, one last attempt was made using the Fuji CR system. Four Fujifilm CR ST-VI plates were made available by the Fuji Non-Destructive Testing (NDT) research and development facility in Stamford, Connecticut, for an image of the chest area. A Foamcore device was constructed to support the plates. With a 40 ft (12.2 m) SID, 75 exposures were taken at 90 kVp with 40 mAs for a total of 3000 mAs. The resulting images indicated that a higher kVp setting would be required to penetrate the "shoulder" area. As the portable unit available for the study had a maximum output of 90 kVp, it was not possible.

Another challenge presented itself as we planned our imaging strategy for two fresco casts mounted back to back on a common wall. Since there were two casts mounted on the opposite side of the display wall, radiographs were taken through the entire wall, thus exposing features from both frescos superimposed on the same image. Radiographs of the two fixed casts mounted on either side of a display wall revealed that large wood screws were used to attach the frescos with the head of the screw being covered in plaster to hide its location (Figure 9.13). Also discovered were repaired cracks that ran diagonally across the fresco from one of the mounting screw locations (Figure 9.14). Endoscopy was then employed to determine which mounting screws seen on the radiograph belonged to which

Figure 9.13 Radiograph of a wall-mounted plaster fresco showing mounting screw heads and additional plaster applications.
Figure 9.14 Radiograph showing a large crack in a wall-mounted fresco at the location of a mounting screw. AIso seen is the endoscope in place.

mounted cast. Endoscopic images also revealed channels of mounting adhesive used in addition to the mounting screws (Figure 9.15). In addition, the images revealed and located the crack emanating from one of the mounting screws and identified in which fresco the crack was present.

Figure 9.15 Radiographic and endoscopic images showing endoscope location. thickened plaster and adhesive can be seen beyond the mounting screw in the endoscopic image on the right.

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