Your Vitamin D level of 9.1 ng/mL indicates a severe deficiency. Between your two options, the oral Calcirol 60K sachets are safer and generally preferred over a massive 600,000 IU injection, which carries a higher risk of toxicity. However, taking 60K twice a week for three months is an unusually high dose. A standard, safer regimen for severe deficiency is taking one Calcirol 60K sachet once a week for 8 to 12 weeks, followed by monthly maintenance. I highly recommend consulting your doctor to prescribe the exact oral frequency and monitor your calcium levels.