Radiation dosimetry and biodistribution of the hypoxia tracer (18)F-EF5 in oncologic patients.
The primary goals of this study were to determine the biodistribution and excretion of (18)F-EF5 in oncologic patients, to estimate the radiation-absorbed dose and to determine the safety of this drug.


METHODS
Sixteen patients with histologically confirmed malignancy received a mean intravenous infusion of 217  MBq (range 107-364  MBq) of (18)F-EF5. Over a 4-6-hour period, four to five serial positron emission tomography (PET) or PET/computed tomography (CT) scans were obtained. To calculate the radiation dosimetry estimates, volumes of interest were drawn over the source organs for each PET scan or on the CT for each PET/CT scan. Serial blood samples were obtained to measure (18)F-EF5 blood clearance. Bladder-wall dose was calculated based on urine activity measurements.


RESULTS
The urinary bladder received the largest radiation-absorbed dose, 0.12 ± 0.034 mSv/MBq (mean ± SD). The average effective dose equivalent and the effective dose of (18)F-EF5 were 0.021 ± 0.003 mSv/MBq and 0.018 ± 0.002 mSv/MBq, respectively. (18)F-EF5 was well tolerated in all subjects.


CONCLUSIONS
(18)F-EF5 was demonstrated to be safe for patients, and the radiation exposure is clinically acceptable. As with any radiotracer with primary excretion in the urine, the bladder-wall dose can be minimized by active hydration and frequent voiding.
Department of Radiation Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Lilie L
LL
Lin
Antti
A
Silvoniemi
James B
JB
Stubbs
Ramesh
R
Rengan
Sami
S
Suilamo
Olof
O
Solin
Chaitanya
C
Divgi
Olli
O
Eskola
Jonathan M
JM
Sorger
Michael G
MG
Stabin
Alexander
A
Kachur
Stephen M
SM
Hahn
Tove J
TJ
Grönroos
Sarita
S
Forsback
Sydney M
SM
Evans
Cameron J
CJ
Koch
Heikki
H
Minn
D000328:Adult; D015687:Cell Hypoxia / Q000502:physiology; D004307:Dose-Response Relationship, Radiation; D017341:Etanidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000652:urine; D005260:Female; D005462:Fluorine Radioisotopes / Q000737:chemistry; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000493:pharmacokinetics* / Q000652:urine; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000652:urine; D049268:Positron-Emission Tomography; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics* / Q000652:urine; D014018:Tissue Distribution; D001743:Urinary Bladder / Q000378:metabolism / Q000528:radiation effects; D055815:Young Adult; D005466:Fluorocarbons
D017341:Etanidazole; D005462:Fluorine Radioisotopes; D006845:Hydrocarbons, Fluorinated; D019275:Radiopharmaceuticals; C096011:2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide; D005466:Fluorocarbons