IEC TS 63070 pdf free download
IEC TS 63070 pdf free download.Ultrasonics – Field characterization – Infrared imaging techniques for determining temperature elevation in tissue-mimicking material and at the radiation surface of a transducer in still air.
7 Phantom specification and construction
7.1 Split TMM specifications
Measurement of the temperature inside a phantom is one goal for observations by the IRcamera. So one of the most important requirements of the phantom is its ability to be split into two pieces of TMM with flat (or slightly convex) cross-sectional surfaces that can be exposed to the IR-camera. TMM is vulnerable to dehydration and mechanical damage. A practical phantom may be kept in a rigid housing in order to avoid dehydration and malfunction caused by cracking the TMM during the operation of combination and separation during the measurement procedure. See Annex A.
The TMM should have acoustic and thermal properties that mimic the appropriate tissue of the human body. The emissivity of the split surface should be known. One of the applicable materials equivalent to soft tissue is specified in IEC 60601-2-37:2007 and IEC 60601-2-37:2007/AMD1:2015; its emissivity was determined in [7] to be 0,94 by comparison with black body tape.
Minimizing multiple reflections of ultrasound between the transducer and the bottom surface of the phantom should be taken into consideration. Lining material, which is used in other circumstances to absorb ultrasound propagating in a water tank and has a high attenuation property, may be appropriately placed at the bottom of the phantom to be effective for this purpose. Bone-mimicking material or sterilized bone fragments [8] [9] [10] should be used as necessary with soft-tissue mimicking material.
If high temperature rise is expected in the TMM, such as when heating with a HITU system, then the properties of the TMM should be known and stable, over the range of expected temperature rises during the measurement.
7.2 Periodic validation
Periodic validation should be performed from the viewpoint of both acoustic and thermal properties. The specified values of attenuation coefficient, thermal conductivity and heat capacity in IEC 60601-2-37:2007 and IEC 60601-2-37:2007/AMD1:2015 should be maintained within the specified tolerances. The period between validations should be one year.
The replacement with new split TMM phantom should be considered when the structural abnormality like cracks and/or the degradation like change of colour are found by visual inspection.
The properties of the selected tissue-mimicking phantom should be appropriate to the tissue being simulated and the purpose of the measurement.
8 Measurement procedure
8.1 Split TMM setup
8.1.1 General
In an infrared measurement there are two phases: first, the ultrasound transducer coupled to the TMM (see recommendation in the last paragraph of 8.1.1) is driven and it generates an acoustic field in the TMM. Heat is generated inside the TMM. Secondly, after a given time of insonation, the configuration of the phantom is changed to allow the IR-camera to observe the two-dimensional temperature distribution over a cross-sectional plane that was inside the TMM during the first phase.
To enable IR-measurements inside the TMM, the TMM consists of two blocks, which make contact during the heating phase and which have to be quickly separated directly after.IEC TS 63070 pdf download.
