A medical image scanner gantry comprising: cooling air delivery manifold comprising: a patient tunnel portion; and a front funnel portion; a plurality of gamma detectors housed inside the medical image scanner gantry and positioned behind the front funnel portion that comprises: an annular interior wall defining an entry opening of the patient tunnel portion; and an air plenum comprising an annular structure for carrying a flow of pressurized air received from a remote source, wherein the air plenum comprises an annular nozzle configured for directing the flow of pressurized air toward the plurality of gamma detectors as a flow of high-velocity air for cooling the plurality of gamma detectors and their associated electronic components; wherein the annular interior wall is nested inside the annular structure of the air plenum, whereby a supplemental air inlet is formed between the annular interior wall and the air plenum, whereby when the flow of high-velocity air flows out of the annular nozzle, ambient air is drawn through the supplemental air inlet and merges with the flow of high-velocity air exiting the annular nozzle and flows toward the plurality of gamma detectors as cooling air flow. cooling air delivery manifold comprising: a patient tunnel portion; and a front funnel portion; a patient tunnel portion; and a front funnel portion; a plurality of gamma detectors housed inside the medical image scanner gantry and positioned behind the front funnel portion that comprises: an annular interior wall defining an entry opening of the patient tunnel portion; and an air plenum comprising an annular structure for carrying a flow of pressurized air received from a remote source, wherein the air plenum comprises an annular nozzle configured for directing the flow of pressurized air toward the plurality of gamma detectors as a flow of high-velocity air for cooling the plurality of gamma detectors and their associated electronic components; wherein the annular interior wall is nested inside the annular structure of the air plenum, whereby a supplemental air inlet is formed between the annular interior wall and the air plenum, whereby when the flow of high-velocity air flows out of the annular nozzle, ambient air is drawn through the supplemental air inlet and merges with the flow of high-velocity air exiting the annular nozzle and flows toward the plurality of gamma detectors as cooling air flow. an annular interior wall defining an entry opening of the patient tunnel portion; and an air plenum comprising an annular structure for carrying a flow of pressurized air received from a remote source, wherein the air plenum comprises an annular nozzle configured for directing the flow of pressurized air toward the plurality of gamma detectors as a flow of high-velocity air for cooling the plurality of gamma detectors and their associated electronic components; wherein the annular interior wall is nested inside the annular structure of the air plenum, whereby a supplemental air inlet is formed between the annular interior wall and the air plenum, whereby when the flow of high-velocity air flows out of the annular nozzle, ambient air is drawn through the supplemental air inlet and merges with the flow of high-velocity air exiting the annular nozzle and flows toward the plurality of gamma detectors as cooling air flow.