Relative biological effectiveness of boron ions on human melanoma cells.
OBJECTIVE
To compare the difference in relative biological effectiveness (RBE) between (10)B ions and a (60)Co gamma-ray beam for human melanoma cells using in vitro cell survival based on a clonogenic assay.


METHODS
Cells were irradiated in vitro under aerobic conditions with (60)Co and (10)B ions with different linear energy transfer (LET) (40, 80 and 160 eV nm(-1)). The dose to the cells was determined using ferrous sulphate dosimetry and an ionisation chamber. The standard linear-quadratic model and the newly proposed repairable conditionally repairable damage (RCR) model were used to calculate the RBE.


RESULTS
The RBE at 10% cell survival for 40, 80 and 160 eV nm(-1) boron ions compared with (60)Co were 1.98 (1.83-2.22), 2.85 (2.64-3.11) and 3.37 (3.17-3.58), respectively, of almost independence of the model used in the calculation.


CONCLUSIONS
Different cell survival models may generate different RBE, especially at low doses and high cell survival levels.
Medical Radiation Physics, Department of Oncology-Pathology, Karolinska Institutet and Stockholm University, Box 260, SE 171 76 Stockholm, Sweden. linda@radfys.ks.se
L M
LM
Persson
M R
MR
Edgren
B
B
Stenerlöw
B K
BK
Lind
I
I
Hedlöf
A R-M
AR
Jernberg
A E
AE
Meijer
A
A
Brahme
D017209:Apoptosis; D016754:Boron Neutron Capture Therapy; D002470:Cell Survival / Q000528:radiation effects; D005434:Flow Cytometry; D006801:Humans; D007477:Ions; D008545:Melanoma / Q000532:radiotherapy*; D008938:Mitosis; D019047:Phantoms, Imaging; D011874:Radiometry; D012062:Relative Biological Effectiveness; D013997:Time Factors; D014407:Tumor Cells, Cultured
D007477:Ions