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← Performing brain surgery without a scalpel - Hyunsoo Joshua No

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Showing Revision 3 created 09/28/2020 by lauren mcalpine .

  1. Every year, tens of thousands of people
    world-wide have brain surgery
  2. without a single incision:
  3. there’s no scalpel, no operating table,
    and the patient loses no blood.
  4. Instead, this procedure takes place
    in a shielded room
  5. with a large machine that emits
    invisible beams of light
  6. at a precise target inside the brain.
  7. This treatment is called
    stereotactic radiosurgery,

  8. and those light beams
    are beams of radiation:
  9. their task is to destroy tumors by
    gradually scrubbing away malignant cells.
  10. For patients, the process begins
    with a CT-scan,

  11. a series of x-rays that produce
    a three-dimensional map of the head.
  12. This reveals the precise location, size,
    and shape of the tumor within.
  13. The CT-scans also help to calculate
    something called "Hounsfield Units,"
  14. which show the densities
    of different tissues.
  15. This offers information
    about how radiation
  16. will propagate through the brain,
    to better optimize its effects.
  17. Doctors might also use
    magnetic resonance imaging, or MRI’s,
  18. that produce finer images of soft tissue,
  19. to assist in better outlining
    a tumor’s shape and location.
  20. Mapping its precise position and size
    is crucial

  21. because of the high doses of radiation
    needed to treat tumors.
  22. Radiosurgery depends on the use
    of multiple beams.
  23. Individually, each delivers a low dose
    of radiation.
  24. But, like several stage lights converging
    on the same point
  25. to create a bright and inescapable
    spotlight, when combined,
  26. the rays of radiation collectively
    produce enough power to destroy tumors.
  27. In addition to enabling doctors to target
    tumors in the brain

  28. while leaving the surrounding
    healthy tissue relatively unharmed,
  29. the use of multiple beams
    also gives doctors flexibility.
  30. They can optimize the best angles
    and routes through brain tissue
  31. to reach the target and adjust
    the intensity within each beam
  32. as necessary.
  33. This helps spare critical structures
    within the brain.
  34. But what exactly does this ingenious
    approach do to the tumors in question?

  35. When several beams of radiation intersect
    to strike a mass of cancerous cells,

  36. their combined force essentially
    shears the cells’ DNA,
  37. causing a breakdown
    in the cells’ structure.
  38. Over time, this process cascades
    into destroying the whole tumor.
  39. Indirectly, the rays also damage the area
    immediately surrounding the DNA,
  40. creating unstable particles
    called free radicals.
  41. This generates a hazardous
    microenvironment
  42. that’s inhospitable to the tumor,
  43. as well as some healthy cells
    in the immediate vicinity.
  44. The risk of harming non-cancerous tissue
    is reduced
  45. by keeping the radiation beam coverage
  46. as close to the exact shape
    of the tumor as possible.
  47. Once radiosurgery treatment has destroyed
    the tumor’s cells,

  48. the body’s natural cleaning
    mechanism kicks in.
  49. The immune system rapidly sweeps
    up the husks of dead cells
  50. to flush them out of the body, while
    other cells transform into scar tissue.
  51. Despite its innovations, radiosurgery
    isn’t always the primary choice

  52. for all brain cancer treatments.
  53. For starters, it’s typically reserved
    for smaller tumors.
  54. Radiation also has a cumulative effect,
  55. meaning that earlier doses can overlap
    with those delivered later on.
  56. So patients with recurrent tumors
  57. may have limitations with future
    radiosurgery treatments.
  58. But these disadvantages weigh up
    against some much larger benefits.

  59. For several types of brain tumors,
  60. radiosurgery can be as successful
    as traditional brain surgery
  61. at destroying cancerous cells.
  62. In tumors called meningiomas,
    recurrence is found to be equal, or lower,
  63. when the patient undergoes radiosurgery.
  64. And compared to traditional surgery—
  65. often a painful experience
    with a long recovery period—
  66. radiosurgery is generally pain-free,
  67. and often requires
    little to no recovery time.
  68. Brain tumors aren’t the only target
    for this type of treatment:

  69. its concepts have been put to use on
    tumors of the lungs, liver, and pancreas.
  70. Meanwhile, doctors are experimenting
    with using it to treat conditions
  71. such as Parkinson’s disease, epilepsy,
    and obsessive compulsive disorder.
  72. The pain of a cancer diagnosis
    can be devastating,
  73. but advancements in these
    non-invasive procedures
  74. are paving a pathway
    for a more gentle cure.