Pitfalls of radiation survey after brachytherapy implant removal preceding Tl-201 study.
An unexpected elevated postimplant radiation survey is described in an elderly patient with an interstitial low-dose-rate iridium-192 (Ir-192) needle implant for endometrial cancer. The elevated activity was related to prolonged clearance of Tl-201 from a cardiac study that had been performed 7 days earlier. The Tl-201 accumulated in the soft tissue, particularly the colon, resulting in increased survey readings over the abdomen and raising concern that an Ir-192 source remained within the patient. This case shows that delayed excretion of a diagnostic radionuclide agent can cause elevated activity high enough to confound postradiotherapy implant survey readings. The estimated surface exposure from a single iridium source left in the pelvis was determined using a phantom study. Possible factors causing decreased excretion of Tl-201 in a patient with heart disease, arteriosclerotic vascular disease, previous pelvic radiation therapy, and a brachytherapy procedure are discussed. A preloading radiation survey is recommended in patients who have had previous nuclear medicine studies involving radionuclides with long half-lives.
Gaston
Robert C
RC
Radiation Oncology Center, Department of Radiological Sciences, Oklahoma University Health Sciences Center, Oklahoma City 73104, USA.
Arnold
Charles D
CD
Ahluwalia
Bhagwat D
BD
Sonnad
Jagadeesh R
JR
Macdurmon
George W
GW
Gold
Michael A
MA
Parry
Cindy K
CK
Montebello
Joseph F
JF
Mayr
Nina A
NA
D000005:Abdomen / Q000000981:diagnostic imaging*; D000230:Adenocarcinoma / Q000532:radiotherapy*; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods; D016889:Endometrial Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D007415:Intestinal Obstruction / Q000000981:diagnostic imaging / Q000209:etiology; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D008657:Metabolic Clearance Rate / Q000502:physiology; D008875:Middle Aged; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism; D011835:Radiation Protection; D011877:Radionuclide Imaging; D013793:Thallium / Q000493:pharmacokinetics*; D014915:Whole-Body Counting / Q000379:methods*
D007496:Iridium Radioisotopes; C027549:thallium chloride; D013793:Thallium