Radiation Absorbed Dose Measurement after I-131 Metaiodobenzylguanidine Treatment in a patient with Pheochromycytoma.
- Author:
Weon Il YANG
;
Byeung Il KIM
;
Jae Sung LEE
;
Jeong Rim LEE
;
Chang Woon CHOI
;
Sang Moo LIM
;
Sung Woon HONG
- Publication Type:Original Article
- Keywords:
Pheochromocytoma;
I-131 MIBG;
Dosimetry;
MIRD
- MeSH:
3-Iodobenzylguanidine;
Female;
Follow-Up Studies;
Gamma Cameras;
Humans;
Kidney;
Lymph Nodes;
Mediastinum;
Middle Aged;
Neoplasm Metastasis;
Nuclear Medicine;
Pheochromocytoma
- From:Korean Journal of Nuclear Medicine
1999;33(4):422-429
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: The measurement of radiation absorbed dose is useful to predict the response after I-131 labeled metaiodobenzylguanidine (MIBG) therapy and determine therapy dose in patients with unresectable or malignant pheochromocytoma. We estimated the absorbed dose in tumor tissue after high dose I-131 MIBG in a patient with pheochromocytoma using a gamma camera and Medical Internal Radiation Dose (MIRD) formula. MATERIALS AND METHODS: A 64-year old female patient with pheochromocytoma who had multiple metastases of mediastinum, right kidney and periaortic lymph nodes, received 74 GBq (200 mCi) of I-131 MIBG. We obtained anterior and posterior images at 0.5, 16, 24, 64 and 145 hours after treatment. Two standard sources of 37 and 74 MBq of I-131 were imaged simultaneously. Cummulated I-131 MIBG uptake in tumor tissue was calculated after the correction of background activity, attenuation, system sensitivity and count loss at a high count rate. RESULTS: The calculated absorbed radiation dose was 32-63 Gy/ 74 GBq, which was lower than the known dose for tumor remission (150-200 Gy). Follow-up studies at 1 month showed minimally reduced tumor size on computed tomography, and mildly reduced I-131 MIBG uptake. CONCLUSION: We estimated radiation absorbed dose after therapeutic I-131 MIBG using a gamma camera and MIRD formula, which can be peformed in a clinical nuclear medicine laboratory. Our RESULTS suggest that the measurement of radiation absorbed dose in I-131 MIBG therapy is feasible as a routine clinical practice that can guide further treatment plan. The accuracy of dose measurement and correlation with clinical outcome should be evaluated further.
