Aras Serhat, Tanzer İhsan Oğuz, İkizceli Türkan
Medical Imaging Programme, University of Health Sciences, İstanbul, Turkey.
Biomedical Technology Programme, University of Health Sciences, İstanbul, Turkey.
Eur J Breast Health. 2020 Mar 31;16(3):167-170. doi: 10.5152/ejbh.2020.5041. eCollection 2020 Jul.
This study compares standard commercial bolus material (Superflab) to custom prepared silicone dental impression material (CDIM) and play dough material (PDM) with respect to dosimetric properties and applicability by using ion chamber measurement and calculated dose values.
The CDIM bolus was prepared by mixing dental impression silicone material with enough water to maintain a density of about 1.0 g/cm. The prepared bolus material is applied on an RW3 solid phantom by covering 10x10 cm area with 0.5-1 cm thickness. Ion chamber measurements were performed separately with and without bolus material application. The setup was scanned in CT and the same procedure was repeated in the TPS using the scan data, in which the Pencil Beam Convolution dose calculation algorithm was used. To compare the effect of bolus material on tissue, the Superflab bolus and CDIM bolus were applied with 1 cm of thickness on postmastectomy scar and dose calculations on TPS were performed.
After comparison of the dosimetric values for Superflab, CDIM and PDM, we obtained statistically meaningful results between superflab and CDIM. For PDM, the results obtained with TPS and ion chamber measurements indicated that, it is not suitable to use in radiotherapy application due to its material properties. For the simulated skin dose values obtained at five random points on the scar tissue, the comparison of Superflab and CDIM TPS calculation results were not statistically significant.
The CDIM is easy to prepare and apply on irregular mastectomy scar tissue and it prevents formation of air gaps in the application surface. Especially for curved anatomical regions such as scar tissue, inclusion of the bolus material in treatment planning protocol will reduce dose uncertainty in application. It is safe to use CDIM as an alternative to Superflab in radiotherapy application, whereas PDM is not useful in clinical practice due to its material properties.
本研究通过离子室测量和计算剂量值，比较标准商用推注材料（Superflab）与定制的硅酮牙科印模材料（CDIM）和橡皮泥材料（PDM）的剂量学特性及适用性。
通过将牙科印模硅酮材料与足够的水混合以维持约1.0 g/cm的密度来制备CDIM推注材料。将制备好的推注材料以0.5 - 1 cm的厚度覆盖在RW3固体模体的10x10 cm区域上。分别在有和没有应用推注材料的情况下进行离子室测量。在CT中对设置进行扫描，并使用扫描数据在TPS中重复相同的过程，其中使用铅笔束卷积剂量计算算法。为了比较推注材料对组织的影响，将Superflab推注材料和CDIM推注材料以1 cm的厚度应用于乳房切除术后的瘢痕上，并在TPS上进行剂量计算。
在比较Superflab、CDIM和PDM的剂量学值后，我们在Superflab和CDIM之间获得了具有统计学意义的结果。对于PDM，TPS和离子室测量获得的结果表明，由于其材料特性，它不适合用于放射治疗应用。对于在瘢痕组织上五个随机点获得的模拟皮肤剂量值，Superflab和CDIM TPS计算结果的比较在统计学上不显著。
CDIM易于制备并应用于不规则的乳房切除术后瘢痕组织，并且它可防止在应用表面形成气隙。特别是对于像瘢痕组织这样的弯曲解剖区域，在治疗计划方案中纳入推注材料将减少应用中的剂量不确定性。在放射治疗应用中使用CDIM作为Superflab的替代品是安全的，而PDM由于其材料特性在临床实践中无用。
