Assessing protection against radiation exposure after prostate (125)I brachytherapy.
OBJECTIVE
To expand the radiation dose rate measurement data set by measuring radiation under various prostate (125)I brachytherapy situations.


METHODS
Measurements were obtained from 63 consecutive unselected patients at Tokyo Medical Center, Japan. Differences in factors during measurements, such as body postures, distances from the skin surface, and measurement directions were considered. Furthermore, shielding effects of lead-lined underwear, consisting mainly of 0.1-mm thickness of lead, were also assessed.


RESULTS
Radiation exposure varies according to the patient's body posture, with results differing as much as approximately 40.0% in measured radiation dose rates at 30cm from the anterior skin surface. Weight, body mass index, and tissue thickness showed good correlations with measured radiation dose rates. The magnitude of radiation exposure attenuation by shielding was approximately 95.8%, similar to the attenuation ratio based on tissue measurements made in the lateral direction. The respective mean times required to reach 1mSv were 1.2, 7.6, and 65.4 days in the standing position and 0.6, 4.6, and 40.4 days in the supine position at the site of contact, and at 30 and 100cm from the anterior skin surface.


CONCLUSIONS
This study obtained supplemental information pertaining to radiological protection and confirmed that shielding can be an effective tool for reducing exposures.
Department of Radiology, Keio University, School of Medicine, Tokyo, Japan; Department of Radiology, Tokyo Medical Center, National Hospital Organization, Tokyo, Japan. Electronic address: thanada@rad.med.keio.ac.jp.
Takashi
T
Hanada
Department of Radiology, Tokyo Medical Center, National Hospital Organization, Tokyo, Japan.
Atsunori
A
Yorozu
Department of Radiology, Saitama Hospital, National Hospital Organization, Saitama, Japan.
Riki
R
Kikumura
Department of Radiology, Keio University, School of Medicine, Tokyo, Japan; Department of Radiology, Saitama Hospital, National Hospital Organization, Saitama, Japan.
Toshio
T
Ohashi
Department of Radiology, Keio University, School of Medicine, Tokyo, Japan.
Naoyuki
N
Shigematsu
D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D007456:Iodine Isotopes / Q000009:adverse effects* / Q000627:therapeutic use; D007564:Japan; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control*; D011835:Radiation Protection / Q000379:methods*; D019275:Radiopharmaceuticals / Q000009:adverse effects / Q000627:therapeutic use; D018570:Risk Assessment
D007456:Iodine Isotopes; D019275:Radiopharmaceuticals
Brachytherapy; Iodine-125; Prostate cancer; Radiation exposure; Radiation safety