Doctors says I need to reach 10,000mg cumulative dosage. I weigh 48kg. Is this normal?

Started accutane yesterday. When I went to go pick up the meds, the doctor was with another patient so I asked front desk how long the total course of treatment would be. She said the doctor would need to do the calculation and she’ll get back to me.

Later she texted me saying that the total dosage I’d have to reach is 10,000mg, based on my body weight of 48kg.

My first reaction is this seems absurdly high? Seeing as some online sources state that the cumulative dose is usually 120mg-150mg per kg of body weight. Even going by 150mg/kg, the cumulative dosage for me would be 7200mg.

Also: 10,000mg➗20mg (per tablet) = 500 tablets 500 tablets➗30 days = 16.7

So that means I’ll need to take the pills for about 16.7 months? This seems like a very long course of treatment compared to the usual that I see…

Any help would be appreciated, thank you!