Abstract

Purpose

The purpose of this study is to investigate the radioprotective effect of melatonin by analyzing histopathological changes and serum biochemical levels on experimental rat models exposed to flattening filter (FF) and flattening filter-free (FFF) beam.

Materials and methods

Forty-eight healthy adult Sprague Dawley rats were randomly divided into six groups. The control (Group 1) was given no treatment, the melatonin (Group 2) was given 10 mg/kg melatonin only, the FF (Group 3) and FFF (Group 5) were given fractionated dose (Total 32 Gy, 5 consecutive days) radiotherapy only, and the FF plus melatonin (Group 4) and FFF plus melatonin (Group 6) were given 10 mg/kg melatonin 15 minutes prior to irradiation. Rats were examined for histopathology and biochemical analysis 10 days after irradiation.

Results

When results of FF and FFF radiotherapy only groups are compared to control group, statistically significant difference in histopathological and biochemical parameters are observed; however, melatonin administration in radiotherapy plus melatonin groups improved these parameters (p <.05). In addition, there was no statistically significant difference between FF and FFF beams (p > .05).

Conclusions

The effect of low- and high-dose beams on the rat larynx and serum samples were investigated histopathologically and biochemically for the first time. We observed that melatonin supplemented before FF and FFF radiotherapy protected early period radiotherapy-induced laryngeal mucosal damage. Since the radiobiological results of FF and FFF beams are similar, FFF beams can be safely applied in laryngeal irradiation. However, more experimental rat and clinical studies are needed to clarify the radiobiological uncertainy concerning dose rate on cancerous and healthy tissue.

中文翻译：

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扁平过滤器 (FF) 和扁平无过滤器 (FFF) 光束在大鼠喉组织中的放射生物学比较

摘要

目的

本研究的目的是通过分析暴露于扁平过滤器 (FF) 和扁平无过滤器 (FFF) 光束的实验大鼠模型的组织病理学变化和血清生化水平来研究褪黑激素的辐射防护作用。

材料和方法

48 只健康成年 Sprague Dawley 大鼠随机分为六组。对照组（第 1 组）不接受治疗，褪黑激素（第 2 组）仅给予 10 mg/kg 褪黑激素，FF（第 3 组）和 FFF（第 5 组）给予分次剂量（总计 32 Gy，连续 5 天） ) 仅放疗，并且 FF 加褪黑激素（第 4 组）和 FFF 加褪黑激素（第 6 组）在照射前 15 分钟给予 10 mg/kg 褪黑激素。辐照后10天检查大鼠的组织病理学和生化分析。

结果

仅FF和FFF放疗组与对照组相比，组织病理学和生化参数有统计学差异；然而，在放疗加褪黑激素组中使用褪黑激素改善了这些参数 ( p  <.05)。此外，FF 和 FFF 光束之间没有统计学上的显着差异 ( p  > .05)。

结论

首次在组织病理学和生化方面研究了低剂量和高剂量光束对大鼠喉部和血清样品的影响。我们观察到在 FF 和 FFF 放疗前补充褪黑激素可以保护早期放疗引起的喉粘膜损伤。由于FF和FFF光束的放射生物学结果相似，FFF光束可以安全地应用于喉部照射。然而，需要更多的实验大鼠和临床研究来澄清有关癌变和健康组织剂量率的放射生物学不确定性。