SPECT Gantry

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• SPECT Gantry
• Presented by
• Besly Clairvoyant, Alina Malave, Jonathan Arias,
  Monica Tevez, Joel Ortega, Nayda Carvi

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History of Nuclear Medicine

• Has its origins in a great many scientific
  discoveries dating back to the invention of the
  X-ray.
• In 1946, radioactive iodine was used to treat a
  patients thyroid cancer.
• In 1950, radioactive nucleotides were being used
  to treat hyperthyroidism.
• Soon after, it was possible to record snapshot
  images of form and structure or organs ( liver,
  spleen, brain, gastrointestinal track, etc.)

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History of SPECT

• Built his first scanner as a first-year medical
  student at Penn.
• Edwards and Kuhl developed the MARK VI, the first
  Emission Computed Tomography (ECT) device.
• MARK VI consisted of several sodium iodide photon
  detectors arranged in the rectangular shape
  around the head of the patient.

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SPECT

• Kuhl went on to develop the procedure known as
  single photon emission computed tomography
  (SPECT) and the principles of positron emission
  tomography (PET).
• SPECT involves detection of gamma rays emitted
  singly from radionuclides such as Tc-99m, I-123,
  and I-111.
• Tomomatic-32, first SPECT imaging device, was
  similar to the MARK VI but has 32 photon
  detectors.

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What is the Gantry?

• The Gantry is the largest part of the SPECT
  system.
• The Gantry supports the cameras rotation around
  the patient, making it possible for images to be
  obtain from different angles.
• Patients can be easily imaged on hospital beds,
  stretchers, or sitting upright, with the help of
  the Gantry.

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Room Requirements

• The room where the camera and Gantry will be
  installed must be prepared for this special
  equipment.
• There must be enough room where the Gantry,
  camera, and bed can fit easily within the room
  and still allow for other equipment and moving
  capabilities.
• The floor also has to be able to hold at least
  4000 lbs due to the very heavy equipment.

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Operating the Gantry

• The Gantry can be controlled both by the
  computer, and by a hand pendant.
• When using the hand pendant the display reads out
  the position to aid the operator ( i.e. vertical,
  horizontal, or various angles.)
• Some Gantry have Intel Pentium based intelligent
  Gantry electronics.
• The Gantry can be pre-programmed with motions for
  positioning.

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Operating the Gantry

• The Gantry moves along floor rails, using a gear
  to both propel itself and calculate its position.
• All motions are motorized and computer
  controlled.

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Interesting Fact

• When researching the Gantry, we found another
  type of Gantry used in Nuclear Medicine.
• In radiation therapy, the Gantry is used for
  rotating the radiation delivery apparatus around
  the patient, so as to treat from different
  angles.
• Radiation therapy is the use of high-energy
  penetrating rays or subatomic particles to treat
  disease.

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Gantry Quality Control

• For a tomographic acquisition in single headed
  SPECT systems, the gantry is usually set to 0o
  and the detector head is leveled prior to an
  acquisition.
• Setting the detector head level is based on the
  assumption that the axis of rotation of the
  detector head is horizontal.
• The axis of rotation is determined by the
  alignment of the gantry.

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Quality Control

• Misalignment of the Gantry can be caused by a
  number of things.
• In many older SPECT systems, sagging of the
  detector arms can occur.
• The Gantry itself may not be leveled on the
  floor. Either due to
• Incorrect shimming of the Gantry
• Irregularities in the surface of the floor

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Quality Control

• Whatever the cause, the consequences are that
  leveling the detector head results in data being
  acquired obliquely rather than perpendicular to
  the axis of rotation.
• For example a 1o Gantry misalignment with the
  detector head at a 20 cm radius of rotation will
  cause a 3.5 mm displacement of image data along
  the axis of rotation.

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Quality Control

• Gantry alignment and its stability with rotation
  can also be easily checked using a small bubble
  level.
• Level the Gantry at 0o, then rotate the Gantry
  through 180o and check that the Gantry is still
  leveled.
• Alignment should be checked once or twice a year
  and after any major upgrade or modification to
  the Gantry.

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Conclusion

• Make sure when setting up a Nuclear Lab that you
  have ample room for all equipment.
• The SPECT Gantry is a very important part of the
  camera.
• The Gantry makes it possible to position the
  patient for imaging.
• It can be operated by computer or by a hand
  pendant.

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• Quality Control is very important on the Gantry
  to make sure proper imaging is done.
• Make sure to check alignment and leveling.
• Alignment should be checked once or twice a year.
• A Gantry that is misaligned will effect an image,
  and Quality Control should be taken very
  seriously in regards to the Gantry.