Relative biological effectiveness of fast neutrons for effects on normal tissues

Journal Article · Sun Jul 01 04:00:00 EDT 1973 · Curr. Top. Radiat. Res. Quart., v. 8, no. 4, pp. 305-350

OSTI ID:4405935

Broerse, J J; Barendsen, G W

Studies on the relative biological effectiveness (RBE) of fast neutrons for effects on normal tissues revealed significantly different values which, in addition to the dose or dose per fraction, depend on the type of tissue investigated. These differences might partly be due to intrinsic differences of the dose response curves of the cells, which are responsible for maintaining the integrity and function of the tissues. RBE values of fast neutrons for effects on different types of normal tissues are compared and, where possible, analyzed with regard to underlying cellular phenomena. The majority of studies of RBE values of neutrons for effects on normal tissues were carried out with fission neutrons, cyclotron-produced neutrons with a mean energy of 8 MeV and monoenergetic 15-MeV neutrons produced by the D-T reaction. Some characteristics of the different fast-neutron beams are discussed with regard to neutron energy spectra, attainable dose rates, gamma contamination of the neutron beam and the energy dissipation patterns. In the LET distributions for the various neutron beams, two important regions can be distinguished which correspond to the energy dissipated through collisions with protons and through interactions with the heavier nuclei, respectively. Under special conditions, the biological effects produced by the protons and by the heavier nuclei can be studied separately. Values of the relative biological effectiveness of fast neutrons for rapidly proliferating cells in various cell-renewal systems will be discussed and related to the radiation syndromes resulting from the depletion of the stem-cell compartment for the specific tissues. RBE values for bone marrow death and intestina1 death are also discussed in relation to the influence of local perturbations of secondary charged particle equilibrium at the bone-soft tissue interface. It is concluded that dosimetric factors do not play a major part in determining the observed differences in RBE values for the two radiation syndromes. Studies of the survival of haemopoietic stem cells and intestinal crypt stem cells indicate that intrinsic differences in radiosensitivity exist between the types of cells investigated. Quantitative studies have only recently been initiated on the responses of tissues with much longer turnover times of functional cells, such as the vascular endothelium, the lung and the spinal cord. Some studies of late effects induced by fast neutrons in these tissues with slow turnover of cells are summarized and the RBE values are compared. Finally, the different RBE values for damage to various types of normal tissues are discussed with regard to the impllcations for fast-neutron radiotherapy. In order to evaluate the possible advantages of fast-neutron radiotherapy, it is necessary to compare the RBE of fast neutrons for eradication of the tumour with the RBE for the normal tissue which is dose-limiting in each particular case considered. (auth)

• Research Organization: Radiobiological Inst. TNO, Rijswijk, Netherlands
• NSA Number: NSA-29-002835
• OSTI ID: 4405935
• Journal Information: Curr. Top. Radiat. Res. Quart., v. 8, no. 4, pp. 305-350, Journal Name: Curr. Top. Radiat. Res. Quart., v. 8, no. 4, pp. 305-350; ISSN CTRQA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*BIOLOGICAL RADIATION EFFECTS
*CELL PROLIFERATION-- BIOLOGICAL RADIATION EFFECTS
*FAST NEUTRONS-- RBE
*TISSUES-- BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL EFFECTS
DOSIMETRY
FISSION NEUTRONS
LET
N48200* --Life Sciences--Radiation Effects on Cells
N48510 --Life Sciences--Radiation Effects on Animals--Man
N48520 --Life Sciences--Radiation Effects on Animals--Vertebrates
NEOPLASMS
PHOTON BEAMS
RADIATION SYNDROME
REVIEWS
STEM CELLS
X RADIATION