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Kilovoltage stereotactic radiosurgery for age‐related macular degeneration: Assessment of optic nerve dose and patient effective dose
Author(s) -
Hanlon Justin,
Lee Choonsik,
Chell Erik,
Gertner Michael,
Hansen Steven,
Howell Roger W.,
Bolch Wesley E.
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3168554
Subject(s) - medicine , optic nerve , radiosurgery , sclera , macular degeneration , dosimetry , nuclear medicine , ophthalmology , radiology , radiation therapy
Age‐related macular degeneration (AMD) is a leading cause for vision loss for people over the age of 65 in the United States and a major health problem worldwide. Research for new treatments of the wet form of the disease using kilovoltage stereotactic radiosurgery is currently underway at Oraya Therapeutics, Inc. In the present study, the authors extend their previous computational stylized model of a single treated eye [Med. Phys. 35, 5151–5160 (2008)] to include full NURBS‐based reference head phantoms of the adult male and female using anatomical data from ICRP Publication 89. The treatment was subsequently modeled in MCNPX 2.5 using a 1 × 1 × 1mm 3voxelized version of the NURBS models. These models incorporated several organs of interest including the brain, thyroid, salivary glands, cranium, mandible, and cervical vertebrae. A higher resolution eye section at 0.5 × 0.5 × 0.5mm 3voxel resolution was extracted from the head phantoms to model smaller eye structures including the macula target, cornea, lens, vitreous humor, sclera/retina layer, and optic nerve. Due to lack of literature data on optic nerve pathways, a CT imaging study was undertaken to quantify the anatomical position of the optic nerve. The average absorbed doses to the organs of interest were below generally accepted thresholds for radiation safety. The estimated effective dose was 0.28 mSv which is comparable to diagnostic procedures such as a head radiograph and a factor of 10 lower than a head CT scan.