title: The histopathologic evaluation of soft tissue changes in rabbit extremity after different dose-fractionation schemes of interstitial high dose rate (HDR) brachytherapy.
abstract: BACKGROUND
  The use of HDR in the treatment of soft tissue sarcoma had been on the rise. However, there was limited study to evaluate the effect of different fractionation schemes on soft tissue and the optimal HDR scheme.
  
  
  OBJECTIVE
  We aimed to assess the histopathologic changes on soft tissue after different HDR brachytherapy doses.
  
  
  METHODS
  The subjects were divided into three groups. Each group included 10 limbs. Group A had only an applicator without radiation, group B received a total of 24 Gy at 6 Gy per fraction, twice a day, and group C received a total of 13.5 Gy in a single fraction. The histopathologic findings were grouped into soft tissue pathology-1 (edema, inflammation, endothelial proliferation, necrosis) and soft tissue pathology-2 (atrophy, calcification, vascular hyalinization, fibrosis) (STP-1-2).
  
  
  RESULTS
  The highest mean grade values of STP-1 and STP-2 were observed in group C (0.95 and 1.45) in comparison to group A (0.45 and 0.85) and group B (0.65 and 0.9). The difference in STP-1 was found significant only between groups A and C and the difference in STP-2 was found both between groups A and C and groups B and C.
  
  
  CONCLUSIONS
  In our experimental study it was shown that the fractionated interstitial HDR had both lower rate and severity of toxicity in comparison to a single high dose fraction. Before using a single fractionated regimen in the clinic, the increased morbidity related to the irreversible early toxicities or progressive late toxicities should be kept in mind.
authors.affiliation: Gazi University Medical School, Department of Radiation Oncology, Turkey.
authors.forename: Ozge Petek
authors.initials: OP
authors.lastname: Erpolat
authors.affiliation: Gazi University Medical School, Department of Radiation Oncology, Turkey.
authors.forename: Muge
authors.initials: M
authors.lastname: Akmansu
authors.affiliation: Gaziantep Avukat Cengiz Gokcek Government Hospital, Department of Pathology, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Dogan
authors.affiliation: Gazi University Medical School, Department of Radiation Oncology, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Bora
authors.affiliation: Gazi University Medical School, Department of Radiation Oncology, Turkey.
authors.forename: Ceren
authors.initials: C
authors.lastname: Kurugol
authors.affiliation: Gazi University Medical School, Department of Pathology, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Uluoglu
keywords: Dose and fractionation; Interstitial HDR brachytherapy; Soft tissue