The effect of small radiation doses on the rat spinal cord: the concept of partial tolerance

Journal Article · Sat Oct 01 00:00:00 EDT 1983 · Int. J. Radiat. Oncol., Biol. Phys.; (United States)

DOI:https://doi.org/10.1016/0360-3016(83)90323-1· OSTI ID:6742985

Ang, K K; Van Der Kogel, A J; Van Der Schueren, E

To evaluate the tolerance of the rat spinal cord to small radiation doses per fraction, an increasing number of fractions is required for induction of paralysis. The assessment of doses of 1-2 Gy, as used in the clinic, would require that over 100 fractions be given. The validity of replacing part of a fractionated irradiation of the spinal cord by a single large dose has been tested. Fractionated irradiation doses with 18 MeV X rays were followed by a ''top-up'' dose of 15 Gy as a single treatment. This is the fraction size of a treatment with two irradiation doses leading to paralysis in 50% of the animals (ED 50). Fractionated treatments were carried out with 2, 5, 10 and 20 fractions followed by the top-up dose of 15 Gy. the isoeffect curve, as a function of the number of fractions, has the same slope as experiments performed without top-up dose. The results show that the quality and quantity of cellular repair is not modified when part of a multifractionated exposure is replaced by a larger top-dose. An important consequence of this finding is, that in treatments with unequal fraction sizes, the partial tolerances can simply be added. Since a top-up dose can replace a sizable number of irradiation treatments, its application will allow investigations of the extent of sublethal damage repair for fraction sizes as low as 1 Gy.

• Research Organization: Div. of Oncology, Leuven, Belgium
• OSTI ID: 6742985
• Journal Information: Int. J. Radiat. Oncol., Biol. Phys.; (United States), Vol. 9:10
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
SPINAL CORD
BIOLOGICAL RADIATION EFFECTS
FRACTIONATED IRRADIATION
HARD X RADIATION
MEV RANGE 10-100
RADIATION DOSES
RATS
TOLERANCE
ANIMALS
BIOLOGICAL EFFECTS
CENTRAL NERVOUS SYSTEM
DOSES
ELECTROMAGNETIC RADIATION
ENERGY RANGE
IONIZING RADIATIONS
IRRADIATION
MAMMALS
MEV RANGE
NERVOUS SYSTEM
RADIATION EFFECTS
RADIATIONS
RODENTS
VERTEBRATES
X RADIATION
560152* - Radiation Effects on Animals- Animals