Exhibit 31.2

Certification
Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

I, James A. MacLennan, Chief
Financial Officer, certify that:

|1. |  | I have reviewed this quarterly report on Form 10-Q of Theragenics
               Corporation® (the Registrant);
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|2. |  | Based on my knowledge, this quarterly report does not contain any untrue
               statement of a material fact or omit to state a material fact necessary to make
               the statements made, in light of the circumstances under which such statements
               were made, not misleading with respect to the period covered by this quarterly
               report;
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|3. |  | Based on my knowledge, the financial statements, and other financial information
               included in this quarterly report, fairly present in all material respects the
               financial condition, results of operations and cash flows of the Registrant as
               of, and for, the periods presented in this quarterly report;
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|4. |  | The Registrants other certifying officer and I are responsible for
               establishing and maintaining disclosure controls and procedures (as defined in
               Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial
               reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
               Registrant and we have:
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|a) |  | designed such disclosure controls and procedures, or caused such disclosure
               controls and procedures to be designed under our supervision, to ensure that
               material information relating to the Registrant, including its consolidated
               subsidiaries, is made known to us by others within those entities, particularly
               during the period in which this quarterly report is being prepared;
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|b) |  | designed such internal control over financial reporting, or caused such internal
               control over financial reporting to be designed under our supervision, to
               provide reasonable assurance regarding the reliability of financial reporting
               and the preparation of financial statements for external purposes in accordance
               with generally accepted accounting principles;
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|c) |  | evaluated the effectiveness of the Registrants disclosure controls and
               procedures and presented in this report our conclusions about the effectiveness
               of the disclosure controls and procedures, as of the end of the period covered
               by this report based on such evaluation; and
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|d) |  | disclosed in this report any change in the Registrants internal control
               over financial reporting that occurred during the Registrants most recent
               fiscal quarter (the Registrants fourth fiscal quarter in the case of an
               annual report) that has materially affected, or is reasonably likely to
               materially affect, the Registrants internal control over financial
               reporting; and
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|5. |  | The Registrants other certifying officer and I have disclosed, based on
               our most recent evaluation of internal control over financial reporting, to the
               Registrants auditors and the audit committee of Registrants board of
               directors (or persons performing the equivalent function):
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|a) |  | all significant deficiencies and material weaknesses in the design or operation
               of internal control over financial reporting which are reasonably likely to
               adversely affect the Registrants ability to record, process, summarize and
               report financial information; and
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|b) |  | any fraud, whether or not material, that involves management or other employees
               who have a significant role in the Registrants internal controls.
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| | Date: May 7, 2004 | 
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| |                                                                        
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| | /s/ James A. MacLennan    James A. MacLennan    Chief Financial Officer