1. What is Tumour Volume Doubling Time?

Tumour Volume Doubling Time (T_d) is the time required for a tumour to double in volume. It's an important parameter in oncology for assessing tumour growth rate and aggressiveness.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( T_d \) — Tumour doubling time (days)
• \( V_1 \) — Initial tumour volume (mm³)
• \( V_2 \) — Final tumour volume (mm³)
• \( t_1 \) — Time at initial measurement (days)
• \( t_2 \) — Time at final measurement (days)
• \( \ln \) — Natural logarithm

Explanation: The formula calculates the exponential growth rate of the tumour between two time points and determines how long it would take to double in volume at that rate.

3. Clinical Significance

Details: Doubling time helps in assessing tumour aggressiveness, planning treatment strategies, and monitoring treatment response. Fast-growing tumours typically have shorter doubling times.

4. Using the Calculator

Tips: Enter tumour volumes in mm³ and time points in days. Ensure V₂ > V₁ and t₂ > t₁ for valid calculations.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical tumour doubling time?
A: Doubling times vary widely: lung cancer (30-180 days), breast cancer (100+ days), aggressive tumors may be <30 days.

Q2: How accurate is volume measurement for irregular tumors?
A: For irregular tumors, volumetric measurements from CT/MRI are more accurate than simple diameter measurements.

Q3: Can this be used during treatment?
A: Yes, changes in doubling time can indicate treatment effectiveness, though response may be non-linear.

Q4: What if the tumour shrinks between measurements?
A: The calculation isn't valid for negative growth rates. It only applies when V₂ > V₁.

Q5: How many measurements are needed for reliable doubling time?
A: Multiple measurements over time provide more reliable estimates than just two points.