BioMed Research International / 2015 / Article / Tab 1

Research Article

Influence of Ionizing Radiation on Two Generations of Cochlear Implants

Table 1

Review of the scientific literature on cochlear implants and radiation therapy.

Authors, yearCochlear implants tested (Nb tested)Implant preparationIrradiation methodDose and fractionation scheme (total dose)Measured parameter,  
observed dysfunctions,  
and critical dose

Ralston et al., 1999 [6]22 MCI (two processor generations)  
24MCI (3p./model)
Two water equivalent plastic blocks (30 × 30 × 5 cm), separated by 1 cm thick Perspex blocksTwo parallel opposed 4 MV photon beams25 × 2 Gy, followed by 5 × 10 Gy and one fraction of 50 (150 Gy)RF-lock and current output.  
50> dose <150 Gy: gradual loss of RF link (CI22M).  
CI24M changes in output current large at 150 Gy.

Baumann et al., 1999 [5]Clarion 1.2 (4p.)10 cm synthetic block, covered by 0.5 cm thick PlexiglasCobalt radiation machine, gamma rays @ 1.2 MVCI1: incr. sequential to (69 Gy)
CI2: 3 × 30 Gy (90 Gy)  
CI3: 34 × 2 Gy (68 Gy)  
CI4: 29 × 2 Gy (58 Gy)
RF-Lock (communication between ICS and speech processor) loss for dose <60 Gy.

Klenzner et al., 2004 [7]Nucleus 24 K (1p.)In situ implantation, cadaver headTwo parallel opposed 6 MV photon beams16.3, 6.2, and 20 Gy (42.5 Gy)Impedance and current output.  
No deficit at tested dose.

Klenzner et al., 2005 [8]Nucleus CI24M (2p.)  
Nucleus I24R (2p.)
Solid-water model simulating head tissue, serving as a phantom implanted deviceTwo parallel opposed 6 MV photon beamsPlan A: 50 × 2 Gy, followed by four fractions of 5 Gy. (120 Gy)  
Plan B: 60 times 1.6 Gy, followed by four fractions of 5 Gy (116 Gy)
Impedance, current output, and charge balance of biphasic pulse.  
No dysfunction 80 Gy.  
Impedance fail at 111 Gy.

Markiewicz et al., 2006 [13]Combi 40+ (1p.)Single in situ case studyTotal body irradiation, 6 MV photons3 × 4 Gy (12 Gy)CI not used on TBI days.  
No reported dysfunctions.

Reddy et al., 2012 [14]  Nucleus CI512 (1p.)Single case study6 MV photons8 × 1.5 Gy (12 Gy)No reported dysfunctions.

Current studyDigisonic SP (3p.)  
Neuro CI (3p.)
Synthetic block, covered by 0.5 cm thick Plexiglas6 MV photons12 × 5 Gy (60 Gy) followed by two fractions of 50 (160 Gy)  
16 × 5 Gy (80 Gy) followed by 20, 40, and 150 (total 290 Gy)
No more than 10% deviation in output currents at 60 or 80 Gy.  
One device out of six dysfunctional after a 290 Gy cumulative dose.

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