Volume effects in Rhesus monkey spinal cord

Journal Article · Sat Apr 30 04:00:00 EDT 1994 · International Journal of Radiation Oncology, Biology and Physics; (United States)

DOI:https://doi.org/10.1016/0360-3016(94)90227-5· OSTI ID:6900639

Schultheiss, T E ^[1]; Stephens, L C; Price, R E; Ang, K K; Peters, L J ^[2]

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1. Fox Chase Cancer Center, Philadelphia, PA (United States)
2. Univ. of Texas, Houston, TX (United States)

An experiment was conducted to test for the existence of a volume effect in radiation myelopathy using Rhesus monkeys treated with clinically relevant field sizes and fractionation schedules. Five groups of Rhesus monkeys were irradiated using 2.2 Gy per fraction to their spinal cords. Three groups were irradiated with 8 cm fields to total doses of 70.4, 77, and 83.6 Gy. Two additional groups were irradiated to 70.4 Gy using 4 and 16 cm fields. The incidence of paresis expressed within 2 years following the completion of treatment was determined for each group. Maximum likelihood estimation was used to determine parameters of a logistic dose response function. The volume effect was modeled using the probability model in which the probability of producing a lesion in an irradiated volume is governed by the probability of the occurrence of independent events. This is a two parameter model requiring only the estimates of the parameters of the dose-response function for the reference volume, but not needing any additional parameters for describing the volume effect. The probability model using a logistic dose-response function fits the data well with the D[sub 50] = 75.8 Gy for the 8-cm field. No evidence was seen for a difference in sensitivities for different anatomical levels of the spinal cord. Most lesions were type 3, combined white matter parenchymal and vascular lesions. Latent periods did not differ significantly from those of type 3 lesions in humans. The spinal cord exhibits a volume effect that is well described by the probability model. Because the dose response function for radiation myelopathy is steep, the volume effect is modest. The Rhesus monkey remains the animal model most similar to humans in dose response, histopathology, and latency for radiation myelopathy. 22 refs., 3 figs., 1 tab.

• OSTI ID: 6900639
• Journal Information: International Journal of Radiation Oncology, Biology and Physics; (United States), Journal Name: International Journal of Radiation Oncology, Biology and Physics; (United States) Vol. 29:1; ISSN 0360-3016; ISSN IOBPD3
• Country of Publication: United States
• Language: English

Related Subjects

560152* -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CENTRAL NERVOUS SYSTEM
MAMMALS
MATHEMATICAL MODELS
MEDICINE
MONKEYS
NERVOUS SYSTEM
NUCLEAR MEDICINE
PRIMATES
RADIATION EFFECTS
RADIOLOGY
RADIOTHERAPY
SIDE EFFECTS
SPINAL CORD
THERAPY
VERTEBRATES