AMENDMENT NO. 3 TO NOTE AND EQUITY PURCHASE AGREEMENT

Exhibit 10.2.4

AMENDMENT NO. 3
TO
NOTE AND EQUITY PURCHASE AGREEMENT

by and among

MGP INSTRUMENTS, INC.

AS BORROWER,

DOSIMETRY ACQUISITIONS (U.S.), LLC (successor by merger to
Dosimetry Acquisitions (U.S.), Inc.)

AS GUARANTOR,

AMERICAN CAPITAL FINANCIAL SERVICES, INC.

AS AGENT

and

THE PURCHASERS IDENTIFIED ON
ANNEX A HERETO

Date of Amendment No. 3: June 30, 2006
Date of Amendment No.2: November 1, 2005
Date of Amendment No. 1: October 22, 2004
Original Date: June 23, 2004

AMENDMENT NO. 3
TO
NOTE AND EQUITY PURCHASE AGREEMENT

$24,944,400 Aggregate Principal Amount of Senior Term B Notes Due June 23, 2010

$12,168,000 Aggregate Principal Amount of Senior Subordinated Notes Due June 23, 2011

$4,867,200 Aggregate Principal Amount of Junior Subordinated Notes Due June 23, 2011

$8,213,400 Revolving Loan Facility

     THIS AMENDMENT NO. 3 TO THE NOTE AND EQUITY PURCHASE AGREEMENT, dated as of June 30, 2006 (this “ Amendment ”), is by and among MGP INSTRUMENTS, INC. (“ Borrower ”), DOSIMETRY ACQUISITIONS (U.S.), LLC (“ Topco ”), as Guarantor, AMERICAN CAPITAL STRATEGIES, LTD. (“ ACAS ”), ACS FUNDING TRUST I (“ AFT ,” and together with ACAS, the “Purchasers”), and AMERICAN CAPITAL FINANCIAL SERVICES, INC., a Delaware corporation (“ ACFS ”), as agent for Purchasers (in such capacity “ Agent ”). Capitalized terms used and not defined elsewhere in this Amendment have the meanings assigned to such terms in the Agreement (as defined below).

RECITALS

     A. The Borrower, ACAS, and ACFS are parties to a Note and Equity Purchase Agreement dated as of June 23, 2004 (as amended to date, the “ Agreement ”), pursuant to which ACAS purchased from the Borrower certain Senior Term B Notes; certain Senior Subordinated Notes; and certain Junior Subordinated Notes.

     B. ACAS has sold or contributed certain of the Notes to AFT.

     C. The Borrower has requested, and Agent and Purchasers have agreed, to extend the Revolving Loan Termination Date until June 23, 2008.

     D. All capitalized terms used but not defined herein shall have the respective meanings ascribed in the Agreement.

     NOW, THEREFORE, the parties hereto, in consideration of the premises and their mutual covenants and agreements herein set forth and intending to be legally bound hereby, covenant and agree as follows:

ARTICLE 1

CONSENT, AMENDMENT AND LIMITED WAIVER

     1.1 Consent . Pursuant to Section 15.2 of the Agreement, each of the undersigned Agent and Purchasers hereby consent to this Amendment and agree, subject to the conditions set forth

herein, that upon the execution hereof, the Agreement is hereby amended as follows and shall be deemed to be amended,