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A treatment planning comparison between a novel rotating gamma system and robotic linear accelerator based intracranial stereotactic radiosurgery/radiotherapy
Phys Med Biol. 2018 Feb;63(3) :035029
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Abstract

 Purpose:
 To compare the dosimetric parameters of a novel Rotating Gamma Ray System (RGS)
 with well-established CyberKnife system (CK) for treating malignant brain
 lesions.
 
 
 Materials and Methods: RGS
 has a treatment head of 16 cobalt-60 sources
 focused to the isocenter, which can rotate 360 degrees on the ring gantry and swing
 35 degrees in the superior direction. We compared several dosimetric parameters in 10 patients
 undergoing brain stereotactic radiosurgery including plan normalization, the number
 of beams and nodes for CK and shots for RGS, collimators used, estimated
 treatment time, D 2 cm and conformity index (CI) among two modalities. 
 
 
 Results:
 The median plan normalization for RGS was 56.7% versus 68.5% (p=0.002) for CK plans. The median number of shots from RGS
 was 7.5 whereas the median number of beams and nodes for CK was 79.5 and 46.
 The median collimator's diameter used was 3.5 mm for RGS as compared to 5 mm for
 CK (p=0.26). Mean D 2 cm was 5.57 Gy for CyberKnife whereas it was 3.11 Gy for
 RGS (p= 0.99). For RGS plans, the median CI was 1.4 compared to 1.3 for the CK
 treatment plans (p= 0.98). The average minimum and maximum doses to optic
 chiasm were 21 and 93 cGy for RGS as compared to 32 and 209 cGy for CK whereas
 these were 0.5 and 364 cGy by RGS and 18 and 399 cGy by CK to the brainstem. The
 mean V12 Gy for brain predicting for radionecrosis with RGS was 3.75 cm3
 as compared to 4.09 cm3 with the CK (p=0.41).
 
 
 Conclusions:
 The dosimetric parameters of a novel RGS with a ring-type gantry are comparable
 with CyberKnife, allowing its use for intracranial lesions and is worth
 exploring in a clinical setting. 
 
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Notes
1361-6560 Fareed, Muhammad Mohsin Orcid: 0000-0002-4286-403x Eldib, Ahmed A Weiss, Stephanie E Hayes, Shelly B Li, Jinsheng Ma, Chang-Ming Charlie Journal Article England Phys Med Biol. 2018 Jan 4. doi: 10.1088/1361-6560/aaa517.