SU-E-T-335: Dosimetric Investigation of An Advanced Rotating Gamma Ray System for Imaged Guided Radiation Therapy

Journal Article · Mon Jun 15 00:00:00 EDT 2015 · Medical Physics

DOI:https://doi.org/10.1118/1.4924696· OSTI ID:22548389

Ma, C; Eldib, A; Chibani, O; Li, J; Chen, L ^[1]; Li, C ^[2]; Mora, G ^[3]

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1. Fox Chase Cancer Center, Philadelphia, PA (United States)
2. Renmin Hospital of Wuhan University, Wuhan (China)
3. Universidade de Lisboa, Codex, Lisboa (Portugal)

Purpose: Co-60 beams have unique dosimetric properties for cranial treatments and thoracic cancers. The conventional concern about the high surface dose is overcome by modern system designs with rotational treatment techniques. This work investigates a novel rotational Gamma ray system for image-guided, external beam radiotherapy. Methods: The CybeRT system (Cyber Medical Corp., China) consists of a ring gantry with either one or two treatment heads containing a Gamma source and a multileaf collimator (MLC). The MLC has 60 paired leaves, and the maximum field size is either 40cmx40cm (40 pairs of 0.5cm central leaves, 20 pairs of 1cm outer leaves), or 22cmx40cm (32 pairs of 0.25cm central leaves, 28 pairs of 0.5cm outer leaves). The treatment head(s) can swing 35° superiorly and 8° inferiorly, allowing a total of 43° non-coplanar beam incident. The treatment couch provides 6-degrees-of-freedom motion compensation and the kV cone-beam CT system has a spatial resolution of 0.4mm. Monte Carlo simulations were used to compute dose distributions and compare with measurements. A retrospective study of 98 previously treated patients was performed to compare CybeRT with existing RT systems. Results: Monte Carlo results confirmed the CybeRT design parameters including output factors and 3D dose distributions. Its beam penumbra/dose gradient was similar to or better than that of 6MV photon beams and its isocenter accuracy is 0.3mm. Co-60 beams produce lower-energy secondary electrons that exhibit better dose properties in low-density lung tissues. Because of their rapid depth dose falloff, Co-60 beams are favorable for peripheral lung tumors with half-arc arrangements to spare the opposite lung and critical structures. Superior dose distributions were obtained for head and neck, breast, spine and lung tumors. Conclusion: Because of its accurate dose delivery and unique dosimetric properties of C-60 sources, CybeRT is ideally suited for advanced SBRT as well as conventional RT. This work was partially supported by Cyber Medical Corp.

• OSTI ID: 22548389
• Journal Information: Medical Physics, Vol. 42, Issue 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
ANIMAL TISSUES
COBALT 60
COMPUTERIZED SIMULATION
COMPUTERIZED TOMOGRAPHY
DEPTH DOSE DISTRIBUTIONS
DOSIMETRY
GAMMA RADIATION
GAMMA SOURCES
IMAGES
LUNGS
MAMMARY GLANDS
MONTE CARLO METHOD
NEOPLASMS
PHOTON BEAMS
RADIATION DOSES
RADIOTHERAPY
SPATIAL RESOLUTION
VERTEBRAE