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

Journal Article · Sat Oct 01 04:00:00 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), Journal Name: Int. J. Radiat. Oncol., Biol. Phys.; (United States) Vol. 9:10; ISSN IOBPD
• 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
DOSES
ELECTROMAGNETIC RADIATION
ENERGY RANGE
FRACTIONATED IRRADIATION
HARD X RADIATION
IONIZING RADIATIONS
IRRADIATION
MAMMALS
MEV RANGE
MEV RANGE 10-100
NERVOUS SYSTEM
RADIATION DOSES
RADIATION EFFECTS
RADIATIONS
RATS
RODENTS
SPINAL CORD
TOLERANCE
VERTEBRATES
X RADIATION