David,I think you are right , its going to be 6 bags of Carbo. I will reconfirm it. Well, Eileen I agree that we shouldn't be second guessing doctor's treament plan. But, thanks for david suggestion we went for a request of audio test. Since my Dad never reported the issue of hearing loss which he had the doctors would have continued with Cisplatin and never checked for hearing issues. So, I feel being pro-active helps and this forum is tremendously helpful with patients sharing info.
My research today , I found that some studies has indicated the scenario where Carboplatin is replaced with Cisplatin, when there is a clear indication of pre-existing hearing loss. And it seems , its still an ongoing debate between Cisplatin vs Carboplatin. And most studies favoring Cisplatin becuase of more potency. The wikipedia abstract says as below:
"Relative to cisplatin, the potency of carboplatin is less potent: depending on the strain of cancer, carboplatin may only be 1/8 to 1/45 as effective. The clinical standard of dosage of carboplatin is usually a 4:1 ratio compared to cisplatin; that is, for a dose that usually requires a particular dose of cisplatin, four times more carboplatin is needed to achieve the same effectiveness. The stable property of carboplatin is a mixed blessing: once uptake of the drug occurs, its retention half-life is considerably longer than cisplatin, but it is also this inertness that causes carboplatin to go right through the human body, and up to 90% of the carboplatin given can be recovered in urine."