Using the MIRD5 Mathematical Phantom to calculate the absorbed dose in organs in case of brain and chest CT scan

Abstract

Purpose: Simulate organs and calculate the absorbed dose in each organ for brain and chest CT scans.

 Method and Materials: In this research; the mathematical phantom MIRD5 for adult men and women was used to calculate the absorbed dose in organs, in the case of brain and chest CT scans. Where; the mathematical phantom MIRD5 and MCNP code were used to simulate organs and calculate the absorbed dose in each organ for brain and chest CT scans, in Voltage (80 KVp, 100 KVp, 120 KVp).

Results:

 For chest scan, the maximum absorbed dose was in scapulae, rib cage, skin, arm bones, breasts, and lungs. For brain scan, the maximum absorbed dose was in the facial skeleton, skin, cranium, Brain, Spine, and scapulae.

With the increase in the value of Voltage, the value of the absorbed dose increases, and the absorbed dose in men is greater than the dose in women.

• For the man's phantom during chest imaging, we find:
• For the woman's phantom during chest imaging, we find:
• For the man's phantom during brain imaging, we find:
• For the woman's phantom during brain imaging, we find:

Conclusion: The difference in the dose values for men and women is due to the difference in the size of the organs, where the structure of the man is larger than the structure of the woman and therefore the values of the dose for the man are larger.

 As a result, for CT chest scan and brain scan, it is necessary to consider all means necessary to reduce the patient's dose such as: lead shielding of healthy organs not subject to scan, and setting voltage and current to low values without reducing image quality.