Serial histopathological changes in irradiated guinea pig lung receiving conventional fractionated and hyperfractionated irradiation.
OBJECTIVE
To determine serial histopathological differences in guinea pig lungs receiving the same total dose as clinically used between conventional fractionated and hyperfractionated irradiation.


METHODS
The guinea pigs received 80 Gy in 40 daily fractions of 2 Gy each (conventional fractionation), 80 Gy in 80 fractions of 1 Gy each twice a day (hyperfractionation), 81 Gy in 27 daily fractions of 3 Gy each (conventional fractionation), or 81 Gy in 54 fractions of 1.5 Gy each twice a day (hyperfractionation). We evaluated the histopathological changes of irradiated guinea pig lungs at 1, 2, 3, 6, 9, and 12 months after irradiation.


RESULTS
The guinea pig lungs that received 81 Gy in 27 daily fractions showed histopathological changes of inflammation including formation of lymph follicles after 6 months. The lungs which received 81 Gy in 54 fractions showed similar but slightly less pronounced changes than those that received 81 Gy in 27 daily fractions. The guinea pig lungs of other groups showed no histopathological changes during the observation period.


CONCLUSIONS
In hyperfractionated irradiation the damage to the guinea pig lung is quantitatively less than that occurring as a result of conventional fractionated irradiation of the same total dose.
Itoh
S
S
Department of Radiology, Kochi Medical School, Nankoku, Japan.
Inomata
T
T
Ogawa
Y
Y
Yoshida
S
S
Sonobe
H
H
Ohtsuki
Y
Y
D000818:Animals; D019583:Dose Fractionation, Radiation; D005260:Female; D006168:Guinea Pigs; D008168:Lung / Q000528:radiation effects*; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000473:pathology*; D013997:Time Factors