The measurement of three dimensional dose distribution of a ruthenium‐106 ophthalmological applicator using magnetic resonance imaging of BANG polymer gels1

Abstract

The BANG (MGS Research Inc., Guilford, CT) polymer gel has been used as a dosimeter to determine the three‐dimensional (3D) dose distribution of a ruthenium‐106 (Ru‐106) ophthalmologic applicator. An eye phantom made of the BANG gel was irradiated with the Ru‐106 source for up to 1 h. The phantom and a set of calibration vials were scanned simultaneously in a GE 1.5 T MR imager using the Hahn spin‐echo pulse sequence with a TR of 2000 ms and two TEs of 20 ms and 100 ms. The T2 values were evaluated on a pixel‐by‐pixel basis using custom‐built software on a DEC alpha workstation and converted to dose using calibration data. Depth doses and isodose lines of the Ru‐106 eye‐plaque were generated. It is concluded that the BANG gel dosimetry offers the potential for measuring the 3D dose distributions of an ophthalmologic applicator, with high spatial resolution and relatively good accuracy.PACS number(s): 87.66.–a, 87.90.+y

15 years of 106 Ru eye plaque dosimetry at Memorial Sloan-Kettering Cancer Center and Weill Cornell Medical Center using radiochromic film in a Solid Water phantom

“…Non-uniform dose distributions with off-axis hot and cold spots were reported using TLDs [13,14] and radiochromic film dosimetry in a Solid Water phantom [12,15]. A variety of methods were employed for 106 Ru eye plaque dosimetry, including but not limited to TLDs [13,14], p-type silicon diode [16], extrapolation chamber [15,17], plastic scintillators [11,15,18], radiochromic film dosimetry [12,15,19,20], BANG gel [21] and liquid scintillator [20]. Soares et al [15] did a cross comparison of eight measurement methods using planar and concave applicators.…”

The three-dimensional scintillation dosimetry method: test for a106Ru eye plaque applicator

“…One of the most important applications of this method may be small brachytherapy applicators with asymmetrical shapes. Examples are eye plaques for treatment of ocular melanoma, which may vary in geometrical design, type of radiation and source isotope used (Hungerford 2003, Chan et al 2001, Flühs et al 2004. There is an increased demand to evaluate the dosimetric properties of this type of device in a short time.…”

Radiation Dosimetry by Use of Radiosensitive Hydrogels and Polymers: Mechanisms, State-of-the-Art and Perspective from 3D to 4D

“…Additional care is required to avoid image distortions caused by magnetic susceptibility related field heterogeneity around the catheter [ 67 ] and contamination of the gel by oxygen from the catheter [ 67 , 299 ]. Polymer gel dosimetry was applied for treatment verification around intravascular sources [ 299 , 300 , 301 , 302 , 303 ], intracavitary brachytherapy [ 242 , 304 , 305 , 306 , 307 , 308 ] and interstitial brachytherapy [ 309 , 310 ]. As with external radiotherapy, polymer gel dosimetry was found of particular importance in end-to-end delivery quality assurance [ 311 , 312 ].…”