X0609 4 2026-09-01 0000728387 Perspective Therapeutics, Inc. CATX 0001521036 Lantheus Holdings, Inc. false 201 BURLINGTON ROAD, SOUTH BUILDING BEDFORD MA 01730 0 0 1 0 0 Common Stock 2026-09-01 4 S 0 35769 3.1193 D 11563425 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.08 to $3.165, inclusive. The reporting person undertakes to provide to Perspective Therapeutics, Inc. ("CATX"), any security holder of CATX or the staff of the Securities and Exchange Commission ("SEC"), upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) to this Form 4. Represents securities directly held by Lantheus Alpha Therapy, LLC ("Lantheus"), a wholly owned indirect subsidiary of Lantheus Holdings, Inc. ("Lantheus Holdings"). Under SEC rules and regulations, Lantheus Holdings may be deemed to have indirect beneficial ownership of the shares held by Lantheus, which has direct beneficial ownership. /s/ Eric M. Green, Vice President, Deputy General Counsel and Assistant Corporate Secretary 2026-09-03