Herold D M, Das I J, Stobbe C C, Iyer R V, Chapman J D
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
Int J Radiat Biol. 2000 Oct;76(10):1357-64. doi: 10.1080/09553000050151637.
To investigate dose enhancement and radiosensitization associated with electrons produced and scattered from gold particles suspended in cells in vitro and with tumour cells growing in vivo irradiated with low-energy photons.
CHO-K1, EMT-6 and DU-145 cells were irradiated with kilovoltage X-ray and Cs-137 beams in slowly stirred suspensions in the presence of various concentrations of gold particles ( 1.5-3.0 microm); cell survival was measured by clonogenic assay. Gold particles were injected directly into EMT-6 tumours growing in scid mice prior to their irradiation. Tumour cell killing was assayed by an in vivo-in vitro technique.
Dose enhancement was confirmed by both Fricke dosimetry and cell killing for 100, 140, 200 and 240 kVp X-rays, but not for Cs-137 gamma-rays. For the chemical dosimeter, a dose enhancement (DMF) of 1.42 was measured for 1% gold particle solutions irradiated with 200 kVp X-rays. When rodent and human cells were irradiated in the presence of 1% gold particles, DMF values at the 10% survival level ranged from 1.36 to 1.54, with an overall average value of 1.43. Preliminary attempts to deliver these gold particles to tumour cells in vivo by intra-tumour injection resulted in modest radiosensitization but extremely heterogeneous distribution.
An increased biologically effective dose can be produced by gold microspheres suspended in cell culture or distributed in tumour tissue exposed to kilovoltage photon beams. With the increasing use of interstitial brachytherapy with isotopes that produce low-energy photons, high-Z particles might find a role for significantly improving the therapeutic ratio.
研究体外悬浮于细胞中的金颗粒产生并散射的电子以及体内生长的肿瘤细胞接受低能光子照射时的剂量增强和放射增敏作用。
在存在不同浓度（1.5 - 3.0微米）金颗粒的情况下，对CHO - K1、EMT - 6和DU - 145细胞在缓慢搅拌的悬浮液中进行千伏级X射线和铯 - 137射线照射；通过克隆形成试验测量细胞存活率。在对裸鼠体内生长的EMT - 6肿瘤进行照射之前，将金颗粒直接注射到肿瘤中。通过体内 - 体外技术测定肿瘤细胞杀伤情况。
通过弗里克剂量测定法和细胞杀伤实验均证实了100、140、200和240 kVp X射线存在剂量增强，但铯 - 137γ射线不存在。对于化学剂量计，用200 kVp X射线照射1%金颗粒溶液时，测得剂量增强（DMF）为1.42。当在1%金颗粒存在下对啮齿动物和人类细胞进行照射时，10%存活水平下的DMF值范围为1.36至1.54，总体平均值为1.43。通过瘤内注射将这些金颗粒递送至体内肿瘤细胞的初步尝试导致了适度的放射增敏，但分布极其不均一。
悬浮于细胞培养物中或分布于接受千伏级光子束照射的肿瘤组织中的金微球可产生增加的生物学有效剂量。随着使用产生低能光子的同位素进行间质近距离治疗的增加，高原子序数粒子可能会在显著提高治疗比方面发挥作用。
