Kozicki Marek, Kwiatos Klaudia, Kadlubowski Slawomir, Dudek Mariusz
Department of Man-Made Fibres, Lodz University of Technology, Lodz, Poland. GeVero Co., Lodz, Poland.
Phys Med Biol. 2017 Jun 23;62(14):5668-5690. doi: 10.1088/1361-6560/aa77eb.
This work reports the first results obtained using a new 3D radiochromic gel dosimeter. The dosimeter is an aqueous physical gel matrix made of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127, PEO-PPO-PEO) doped with a representative of tetrazolium salts, 2, 3, 5-triphenyltetrazolium chloride (TTC). There were several reasons for the choice of Pluronic as a gel forming substrate: (i) the high degree of transparency and colourlessness; (ii) the possibility of gel dosimeter preparation at both high and low temperatures due to the phase behaviour of Pluronic; (iii) the broad temperature range over which the TTC-Pluronic dosimeter is stable; and (iv) the non-toxicity of Pluronic. A reason for the choice of TTC was its ionising radiation-induced transformation to water-insoluble formazan, which was assumed to impact beneficially on the spatial stability of the dose distribution. If irradiated, the TTC-Pluronic gels become red but transparent in the irradiated part, while the non-irradiated part remains crystal clear. The best obtained composition is characterised by <4 Gy dose threshold, a dose sensitivity of 0.002 31 (Gy × cm), a large linear dose range of >500 Gy and a dynamic dose response much greater than 500 Gy (7.5% TTC, 25% Pluronic F-127, 50 mmol dm tetrakis). Temporal and spatial stability studies revealed that the TTC-Pluronic gels (7.5% TTC, 25% Pluronic F-127) were stable for more than one week. The addition of compounds boosting the gels' dose performance caused deterioration of the gels' temporal stability but did not impact the stability of the 3D dose distribution. The proposed method of preparation allows for the repeatable manufacture of the gels. There were no differences observed between gels irradiated fractionally and non-fractionally. The TTC-Pluronic dose response might be affected by the radiation source dose rate-this, however, requires further examination.
本研究报告了使用新型3D放射变色凝胶剂量计获得的首批结果。该剂量计是一种水性物理凝胶基质，由聚（环氧乙烷）-嵌段-聚（环氧丙烷）-嵌段-聚（环氧乙烷）（普朗尼克F-127，PEO-PPO-PEO）制成，并掺杂了一种四唑盐代表物，即2,3,5-三苯基氯化四唑（TTC）。选择普朗尼克作为凝胶形成基质有几个原因：（i）高度透明且无色；（ii）由于普朗尼克的相行为，可在高温和低温下制备凝胶剂量计；（iii）TTC-普朗尼克剂量计稳定的温度范围较宽；（iv）普朗尼克无毒。选择TTC的一个原因是其在电离辐射下会转化为水不溶性的甲臜，这被认为对剂量分布的空间稳定性有有益影响。如果受到辐照，TTC-普朗尼克凝胶会变红，但辐照部分仍保持透明，而未辐照部分则保持清澈透明。所获得的最佳组合物的特征在于剂量阈值<4 Gy，剂量灵敏度为0.002 31（Gy×cm），线性剂量范围大于500 Gy，动态剂量响应远大于500 Gy（7.5% TTC，25%普朗尼克F-127，50 mmol dm四（羟甲基）鏻氯化物）。时间和空间稳定性研究表明，TTC-普朗尼克凝胶（7.5% TTC，25%普朗尼克F-127）可稳定一周以上。添加提高凝胶剂量性能的化合物会导致凝胶时间稳定性下降，但不会影响三维剂量分布的稳定性。所提出的制备方法可实现凝胶的可重复制造。分次照射和非分次照射的凝胶之间未观察到差异。TTC-普朗尼克剂量响应可能会受到辐射源剂量率的影响——然而，这需要进一步研究。
