Levine, J. (dissenting). We respectfully dissent. In focusing exclusively on the language of modifier "-62” in the "General Information and Rules” (hereinafter general rules) of the radiology section of the Medicaid Management Information System (hereinafter MMIS) Provider Manual, the majority, in our view, misses the point of defendant’s rationale for applying the -62 modifier to plaintiffs charges for multiple sonograms performed on the same patient during a single visit. The applicable provision is rule 3 of the general rules of the radiology section of the MMIS Provider Manual. Rule 3 states in pertinent part: When multiple x-ray examinations are performed during the same visit, the charge shall be based on the greater fee plus 60% of the lesser fee(s). (See MMIS Modifier '-62’.)” The applicability of the -62 modifier thus arises out of its incorporation by reference in rule 3.
*16While rule 3 speaks in terms of multiple X-ray examinations, it is preceded by the introductory paragraph of the general rules of the radiology section of the MMIS Provider Manual which clearly specifies that "[t]hese rules apply to all procedure codes found in the Radiology Section of this Fee Schedule including diagnostic radiology, radiotherapy, nuclear medicine, ultrasound and CT scan procedures” (emphasis supplied). Thus, although an X ray and an ultrasound are concededly different radiological techniques, the MMIS Provider Manual makes them the same for purposes of the general rules governing Medicaid charges for radiological diagnostic services. Accordingly, there is nothing unreasonable in applying the billing restrictions for multiple, single-visit X-ray examinations contained in rule 3 to multiple, single-visit sonograms. Likewise, it seems obvious that, although rule 4 of the radiology general rules bars payment for "repeat x-ray examinations * * * required because of technical or professional error in the original x-rays”, it would equally apply to repeat sonograms or CT scans required because of such errors. Indeed, to hold otherwise would be to eliminate any meaning or application of the previously quoted introductory provision of the radiology general rules, making "[t]hese rules” applicable to all such radiological procedures.
In our view, then, it was entirely reasonable for defendant to interpret rule 3 of the radiology general rules in the MMIS Provider Manual as applicable to plaintiff’s charges for multiple, single-visit ultrasounds, by virtue of which he was limited to payment of 100% of the schedule fee for the most costly procedure he performed, plus 60% of the schedule fee for all other procedures performed on the patient during the same visit. The uncontested explanation of the purpose underlying this restriction on billing for multiple, single-visit radiological procedures, i.e., to reflect the fact that a radiologist achieves cost savings performing multiple procedures on the same patient in a single session, "since the patient is already present and prepared for the procedure”, is contained in the affidavit of a bureau director in defendant’s Division of Medical Assistance submitted on defendant’s cross motion for summary judgment. The 60% billing restriction for procedures subsequent to the first procedure during a single visit attempts to "pass some of [the] savings [in the radiologist’s time and labor] on to the Medicaid program”. The affiant also states, without contradiction in the record, that the foregoing rationale for rule 3 and the MMIS -62 modifier applies with *17equal force "regardless of whether the radiologist is using x-rays or ultrasound”.
When, as here, the interpretation by the administrative agency of its own rules and regulations is not irrational or unreasonable, it should be upheld (see, Matter of Johnson v Joy, 48 NY2d 689, 691). Repeatedly, the courts have deferred to the administrative construction of the agency’s rules when, as in the instant case, that interpretation is not irrational or contrary to the governing statute (see, Matter of Spizzirro v Ayala, 176 AD2d 738, 739; Matter of Lipes v State of New York, Div. of Hous. & Community Renewal, Off. of Rent Admin., 174 AD2d 571, 572; Matter of Silver Lake Nursing Home v Axelrod, 156 AD2d 789, 790; Matter of Fiorillo v New York State Dept. of Envtl. Conservation, 123 AD2d 151, 153, appeal dismissed 70 NY2d 641). Moreover, as demonstrated by the aforementioned affidavit of the bureau director of defendant’s Division of Medical Assistance, application of the rules here involves the agency’s knowledge and understanding of underlying radiological practices (see, Matter of Fiorillo v New York State Dept. of Envtl. Conservation, supra). Contrary to the majority’s position, the deference due an administrative agency’s interpretation of its own rules and regulations is not limited to instances where the language under review is technical terminology within the agency’s expertise. At least in part, deference in interpretation is accorded the agency as drafter of the regulation "because the administrators are likely to know more about the background of intent that went into the regulation” (2 Davis, Administrative Law § 7:22, at 107 [2d ed]). Accordingly, an agency’s interpretation of its own regulations is entitled to even more deference than its interpretation of the statute it has the responsibility of enforcing (see, Udall v Tallman, 380 US 1, 16; Bowles v Seminole Rock Co., 325 US 410, 413-414; see also, Lyng v Payne, 476 US 926, 939; Immigration Serv. v Stanisic, 395 US 62, 72).
Inasmuch as application of the billing restrictions of rule 3 of the general rules of the radiology section of the MMIS Provider Manual to multiple, single-visit ultrasound procedures is consistent with the purpose of that rule and it has not been shown to conflict with any of the provisions of the MMIS Reimbursement Schedule or Provider Manual, defendant’s interpretation should be upheld (see, Matter of Kaufman v Sarafan, 59 NY2d 855, 857).
For all the foregoing reasons, we would reverse Supreme *18Court’s judgment, grant defendant’s cross motion for summary judgment and make a declaration in its favor.
Mikoll, J. P., and Casey, J., concur with Harvey, J; Levine and Crew III, JJ., dissent in a separate opinion by Levine, J.
Ordered that the judgment is affirmed, with costs.