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.
Persson
L M
LM
Medical Radiation Physics, Department of Oncology-Pathology, Karolinska Institutet and Stockholm University, Box 260, SE 171 76 Stockholm, Sweden. linda@radfys.ks.se
Edgren
M R
MR
Stenerlöw
B
B
Lind
B K
BK
Hedlöf
I
I
Jernberg
A R-M
AR
Meijer
A E
AE
Brahme
A
A
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