Medical Imaging Techniques Programme, University of Health Sciences Turkey, Istanbul, Turkey.
Biomedical Technology Programme, University of Health Sciences Turkey, Istanbul, Turkey.
Int J Radiat Biol. 2021;97(2):249-255. doi: 10.1080/09553002.2021.1857457. Epub 2021 Jan 6.
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.
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.
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 ( <.05). In addition, there was no statistically significant difference between FF and FFF beams ( > .05).
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.
本研究旨在通过分析实验大鼠模型在接受平野滤过（FF）和非平野滤过（FFF）射束照射后的组织病理学变化和血清生化水平，研究褪黑素的放射防护作用。
将 48 只健康成年 Sprague Dawley 大鼠随机分为 6 组。对照组（第 1 组）未给予任何治疗，褪黑素组（第 2 组）仅给予 10mg/kg 褪黑素，FF 组（第 3 组）和 FFF 组（第 5 组）给予分次剂量（总剂量 32Gy，连续 5 天）单纯放射治疗，FF 加褪黑素组（第 4 组）和 FFF 加褪黑素组（第 6 组）在照射前 15 分钟给予 10mg/kg 褪黑素。照射后 10 天对大鼠进行组织病理学和生化分析检查。
与对照组相比，仅接受 FF 和 FFF 放射治疗的两组的组织病理学和生化参数有统计学显著差异；然而，放射治疗加褪黑素组给予褪黑素可改善这些参数（ <.05）。此外，FF 和 FFF 射束之间无统计学显著差异（ > .05）。
首次从组织病理学和生物化学角度研究了低剂量和高剂量射束对大鼠喉和血清样本的影响。我们观察到，在 FF 和 FFF 放射治疗前补充褪黑素可保护早期放射诱导的喉黏膜损伤。由于 FF 和 FFF 射束的放射生物学结果相似，因此 FFF 射束可安全地应用于喉照射。然而，需要更多的实验大鼠和临床研究来阐明剂量率对癌性和健康组织的放射生物学不确定性。
