Effect of same-dose single or dual field irradiation on damage to miniature pig parotid glands.
OBJECTIVE
To evaluate the effect of single or dual field irradiation (IR) with the same dose on damage to miniature pig parotid glands.


METHODS
Sixteen miniature pigs were divided into two IR groups (n=6) and a control group (n=4). The irradiation groups were subjected to 20 Gy X-radiation to one parotid gland using single-field or dual-field modality by linear accelerator. The dose-volume distributions between two IR groups were compared. Saliva from parotid glands and blood were collected at 0, 4, 8 and 16 weeks after irradiation. Parotid glands were removed at 16 weeks to evaluate tissue morphology.


RESULTS
The irradiation dose volume distributions were significantly different between single and dual field irradiation groups (t=4.177, P=0.002), although dose volume histogramin (DVH) indicated the equal maximal dose in parotid glands. Saliva flow rates from IR side decreased dramatically at all time points in IR groups, especially in dual field irradiation group. The radiation caused changes of white blood cell count in blood, lactate dehydrogenase and amylase in serum, calcium, potassium and amylase in saliva. Morphologically, more severe radiation damage was found in irradiated parotid glands from dual field irradiation group than that from single field irradiation group.


CONCLUSIONS
Data from this large animal model demonstrated that the radiation damage from the dual field irradiation was more severe than that of the single field irradiation at the same dose, suggesting that dose-volume distribution is an important factor in evaluation of the radiobiology of parotid glands.
Yan
Xing
X
Salivary Gland Disease Center and the Molecular Laboratory for Gene Therapy, Capital Medical University School of Stomatology, Beijing, China.
Hai
Bo
B
Shan
Zhao-chen
ZC
Zheng
Chang-yu
CY
Zhang
Chun-mei
CM
Wang
Song-lin
SL
D000681:Amylases / Q000032:analysis / Q000097:blood / Q000528:radiation effects; D000818:Animals; D001792:Blood Platelets / Q000528:radiation effects; D002118:Calcium / Q000032:analysis / Q000528:radiation effects; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000528:radiation effects; D007770:L-Lactate Dehydrogenase / Q000097:blood / Q000528:radiation effects; D007958:Leukocyte Count; D007962:Leukocytes / Q000528:radiation effects; D008297:Male; D023421:Models, Animal; D009929:Organ Size / Q000528:radiation effects; D010306:Parotid Gland / Q000473:pathology / Q000528:radiation effects*; D011188:Potassium / Q000032:analysis / Q000528:radiation effects; D011829:Radiation Dosage; D011897:Random Allocation; D012463:Saliva / Q000737:chemistry / Q000528:radiation effects; D012636:Secretory Rate / Q000528:radiation effects; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors
D007770:L-Lactate Dehydrogenase; D000681:Amylases; D011188:Potassium; D002118:Calcium