Abstract

The technique of multiplex holography (Reference 1) was used to form a three dimensional display of 57Co radionuclide decay in a standard Alderson head phantom. Reconstructed in white light, the image appears as a collection of points of light behind a semicylindrical sheet of transparent film against a black background. The distribution of the points of light corresponds to the distribution of the radionuclide in the head phantom.

In the past three years progress has been made in the process of multiplex holography by Lloyd Cross and his associates at the Multiplex Company in San Francisco. The multiplex holograms produced there depict moving, three dimensional images when reconstructed in white light. Scintiholography is the adaptation of conventional scintiphotography to this process.

Materials and Methods

The process of multiplex holography requires two steps. First, two dimensional images are recorded in 1/3 degree intervals around the subject using a 35mm motion picture camera and black and white film. These images are then multiplexed holographically onto a single sheet of holographic film 9 1/2 inches wide, curved to form a 120 degree semi-cylinder with a 9 inch radius. When reconstructed with a clear 100 watt incandescent bulb with a vertical filament, the three dimensional image of the subject appears to the viewer hovering in the center of the semicylinder. The image color goes as a rainbow from red to violet, top to bottom. This is a characteristic of the white light hologram. When the viewer moves around the multiplex hologram, the image is seen from correspondingly different points of view. By splicing three 120 degree multiplex holograms together, a 360 degree hologram can be made.

The subject of the Scintihologram was an Alderson head phantom placed on a rotatable turntable. The phantom was loaded with approximately 2 1/2 mCi of 57Co. An Angar-style scintillation camera (Searle Radiographics Pho/Gamma IV) fitted with a parallel hole collimator was placed approximately 14 inches from the axis of the turntable (see Figure 1).

An Arriflex II C-B 35mm motion picture camera was used to integrate and record events displayed on the CRT display of the scintillation camera. Scintiphotos were recorded of the subject every 1/2 degree for 180 degrees. For each view, 80,000 events were integrated and recorded on one frame of motion picture negative film. A total of 360 images were recorded, one frame for each 1/2 degree of rotation. The motion picture film negative was processed and printed. The print was then holographically multiplexed by the Multiplex Company to form a Scintihologram.

Results and Discussion

The Scintihologram was reconstructed in the configuration shown in Figure 2.

The reconstructed image appears as a collection of points of light, each point of light corresponding to a detected gamma photon. By moving around the Scintihologram, the phantom can be viewed from different points of view.

The major features of the phantom are clearly visible. Two bright constellations correspond to the two "hot" areas of the phantom. The two "cold" discs fastened to the sides of the phantom are seen as discs defined by the surrounding points of light. The back side of the disc on the phantom's left can be seen looking through the phantom from the opposite side.

Because of the mechanical restrictions of the turntable, the phantom was indexed in 1/2 degree intervals rather than 1/3 degree intervals. After being multiplexed in 1/3 degree intervals, the reconstructed image appears wider than normal.

The areas in the Scintihologram of highest recorded photon density appear to have depth, but as the recorded photon density decreases, the impression of depth decreases. To perceive depth, light emanating from a point on an object must be observed by both eyes simultaneously. The two dimensional scintiphotos which make up the Scintihologram were taken a different points in time, and there is no guarantee that photons from random decay will emanate from the same point in space for successive views. Smearing the image enhances the perception of depth, but reduces the image contrast. Smearing can be accomplished simply by tilting the filament slightly out of the vertical.

Acknowledgments

The work was financed and performed by the author with the help of Jim Abbott, Gary Adams, Bob Anwyl, Lloyd Cross, Valerie Delosier, Ed Fairstein, Bill Gibbs, Ray Hayes, Mike Hebenstreit, Harold Kerley, and Bill Stark.

References

1. CROSS LG, et al: personal communications with the Multiplex Company, 454 Shotwell Street, San Francisco, California.

2. BUDINGER TF, GULLBERG GT: Special Issue on Physical and Computational Aspects of 3-Dimensional Image Reconstruction, IEEE Transactions on Nuclear Science NS-21 No. 3: 2-20, 1974

3. DeBITETTO DJ: Holographic panoramic stereogram synthesized from white light recordings, Applied Optics 8: 1740-1741, 1969.

This is a photograph of the Alderson phantom used as the subject of the Scintihologram. The phantom consists of a human skull mounted within a water-tight plastic case shaped like a human head. Radioisotope solutions are introduced into the phantom through ports in the top. The phantom features two chambers within the skull designed to simulate tumors. For the Scintihologram, three dilutions of 57Co were loaded into the phantom: one "hottest" dilution into the lower front "tumor", one "hot" dilution into the upper rear "tumor", and a mild dilution into the head chamber to serve as background.

Here is a stereo pair recorded directly from a Scintihologram. Note the two bright orbs corresponding to the two "tumors". The black line running vertically through the image is a holographic error. The Scintihologram is composed of many thin vertical 3-D holograms, one for each frame of 2-D film. The process of recording a hologram is extremely sensitive to vibration. Elaborate equipment and procedures are used to insure that physical movement is reduced to less than about a 20th wavelength of light during exposure. The black line in the Scintihologram indicates that that particular hologram failed during recording due to movement.

Here is another stereo pair taken from a different perspective. The two "tumors" are clearly visible.

Click on the links below to access a movie of the Scintihologram being rotated in front of the camera.

Note 1: This previously unpublished manuscript was submitted to the Journal of Nuclear Medicine in April of 1976. The work was first proposed by the author in January of 1974 and then completed in March of 1975. The Scintihologram was subsequently exhibited at the June 1975 Society of Nuclear Medicine Conference in Philadelphia, Pennsylvania; at the International Center for Photography in New York in the Fall of 1975; and at the Stockholm Cultural Center in Stockholm, Sweden during March 12-28, 1976.²

Note 2: The original Scintihologram print was loaned to Ms. Loren Billings at the Gallery 1134 in Chicago, Illinois in 1978. I visited Ms. Billings in 2000 to request return of the Scintihologram, but she claimed she didn't know what had happened to it. Please contact me if you have information about the original Scintihologram's whereabouts.³

Note 3: Thanks to the efforts of Ed Wesly (Eddie Wiercioch), the Scinithologram was returned to me after 39 years!

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