Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114, USA.
Med Phys. 2010 Jan;37(1):183-8. doi: 10.1118/1.3260844.
Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O/C ratio) is very desirable to ensure realistic time-activity measurements.
Glucose and urea was added to the original MAGIC formulation to adjust the O/C ratio. The dose responses of the new formulations were tested with MRI transverse relaxation rate (R2) measurements.
The new ingredients improved not only the elemental composition but also the sensitivity of the MAGIC gel. The O/C ratios of our new gels agree with that of soft tissue within 1%. The slopes of dose response curves were 1.6-2.7 times larger with glucose. The melting point also increased by 5 degrees C. Further addition of urea resulted in a similar slope but with an increased intercept and a decreased melting point.
Our improved MAGIC gel formulations have higher sensitivity and better elemental tissue equivalency for 3D dosimetry applications involving nuclear reactions.
基于聚合物的凝胶剂量计（MAGIC 型）是质子束治疗的 PET 范围验证的首选体模材料。然而，为了确保真实的时间活性测量，非常需要提高元素组织等效性（特别是 O/C 比）。
向原始 MAGIC 配方中添加葡萄糖和尿素，以调整 O/C 比。使用 MRI 横向弛豫率（R2）测量来测试新配方的剂量响应。
新成分不仅改善了元素组成，还提高了 MAGIC 凝胶的灵敏度。我们新凝胶的 O/C 比与软组织的 O/C 比相差在 1%以内。葡萄糖使剂量响应曲线的斜率增加了 1.6-2.7 倍。熔点也升高了 5 摄氏度。进一步添加尿素会导致斜率相似，但截距增加，熔点降低。
我们改进的 MAGIC 凝胶配方具有更高的灵敏度和更好的元素组织等效性，适用于涉及核反应的 3D 剂量测定应用。
