Samenvatting
Purpose
Extended serial x-ray exposures that are associated with in-vivo micro-CT scans could become a significant factor in animal cancer studies because experimental outcomes such as animal survival or tumor growth may be altered due to radiation induced health effects. The purpose of this study was to evaluate radiation organ doses to mice from micro-CT scans with two methods.
Methods and Materials
Organ doses were measured on a dual tube micro-CT scanner (Skyscan 1178) with a scanresolution of 83 µm, 50 kV, 0.615 mA, 121 s acquisition time and no table movement. Healthy euthanized C57bl/6 mice (n=5) were packed with 15 individually calibrated lithium fluoride thermoluminescent dosimeters (TLD-100). TLDs were placed in the following organs: lungs, liver, stomach, spleen, colon, bladder and subcutaneous tissue. Also the CTDI100 was measured with a 100 mm ionization chamber, centrally positioned in a 2.7 cm diameter water phantom.
Results
Internal TLD analysis demonstrated a median mouse organ dose of 5,46_0.6 mGy per mAs or 40.6_4.4 cGy per single scan. The CTDI100 measured in the water phantom was observed to give a comparable result of 6.56 mGy per mAs. The largest organ dose (6.81 mGy/mAs) was absorbed by the subcutaneous tissue.
Conclusion
Animal cancer studies have demonstrated tumor growth inhibition associated with the organ dose levels observed in this study. Inter-organ dose variation appears to be small; results suggest that dose optimization studies could be performed with the use of only a few TLDs. A CTDI ionization chamber, which is usually available in a radiology department, could also be used.
Extended serial x-ray exposures that are associated with in-vivo micro-CT scans could become a significant factor in animal cancer studies because experimental outcomes such as animal survival or tumor growth may be altered due to radiation induced health effects. The purpose of this study was to evaluate radiation organ doses to mice from micro-CT scans with two methods.
Methods and Materials
Organ doses were measured on a dual tube micro-CT scanner (Skyscan 1178) with a scanresolution of 83 µm, 50 kV, 0.615 mA, 121 s acquisition time and no table movement. Healthy euthanized C57bl/6 mice (n=5) were packed with 15 individually calibrated lithium fluoride thermoluminescent dosimeters (TLD-100). TLDs were placed in the following organs: lungs, liver, stomach, spleen, colon, bladder and subcutaneous tissue. Also the CTDI100 was measured with a 100 mm ionization chamber, centrally positioned in a 2.7 cm diameter water phantom.
Results
Internal TLD analysis demonstrated a median mouse organ dose of 5,46_0.6 mGy per mAs or 40.6_4.4 cGy per single scan. The CTDI100 measured in the water phantom was observed to give a comparable result of 6.56 mGy per mAs. The largest organ dose (6.81 mGy/mAs) was absorbed by the subcutaneous tissue.
Conclusion
Animal cancer studies have demonstrated tumor growth inhibition associated with the organ dose levels observed in this study. Inter-organ dose variation appears to be small; results suggest that dose optimization studies could be performed with the use of only a few TLDs. A CTDI ionization chamber, which is usually available in a radiology department, could also be used.
| Originele taal-2 | English |
|---|---|
| Tijdschrift | European Radiology |
| Volume | 18 |
| Status | Published - 1 feb. 2008 |