Dosimetric Comparison of Scalp Protection in Whole Brain Radiotherapy Due to Brain Metastasis

Objective: The objective is to demonstrate dosimetrically the preservation of scalp in whole-brain irradiation in the treatment of brain metastases and to make dosimetry at 20 points determined on the rando phantom while comparing between Linac and Tomotherapy devices. In this way, if it is supported by clinical studies in the following years while giving more doses to the tumor, the damage to the traumatic functions due to hair loss can be prevented under scalp protection. Method: 10 randomized patients, who had previously undergone radiotherapy for whole-brain metastasis cancer, were determined prospectively. In Helical Tomotherapy (HT) and Linac devices, Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) were planned to be 30 Gray (Gy) 10 Fractions for the whole brain region. Result: The average target volume (PTV) Homogeneity index (HI), conformity index (CI) and integral dose (ID) were found for IMRT and VMAT as 0.075, 0.77, 0.94, 0.97 and 29.67, 23.57, respectively. Mean and median doses for scalp IMRT and VMAT were 19.71Gy and 18.01 Gy (p<0.005). Lenses and body doses were statistically significant for IMRT and Vmat. The mean median plan doses for Rando phantom scalp were 19.43 Gy and 19.55 Gy in IMRT and VMAT, respectively. The mean median film doses for Rando phantom scalp were 17.03 Gy and 20.64 Gy in IMRT and VMAT, respectively (p<0.005). Conclusion: By using both VMAT and Helical Tomotherapy techniques, it is possible to dry the lens and scalp without low PTV doses in whole-brain irradiation.