Submit Public Comments on DICOM Supplement 229: Photoacoustic Imaging

DICOM invites stakeholders to submit comments on Supplement 229: Photoacoustic Imaging.

Scope and Field of Application
This Supplement to the DICOM Standard introduces a new IOD and a new storage SOP Class for encoding and storing photoacoustic images.
Photoacoustic (PA) imaging is an imaging modality that enables imaging optical absorption in biological tissues with acoustic resolution. Contrast is generated through absorption by chromophores that range from intrinsic absorbers such as hemoglobin and melanin to extrinsic agents such as indocyanine green (ICG) or diverse types of nano-particles. In principle, excitation at multiple wavelengths allows the modality to discriminate individual chromophores. Prospective applications in the space of clinical imaging range from classification of breast cancer lesions through screening of sentinel lymph nodes to assessment of inflammation. Photoacoustic Imaging is in widespread use in preclinical research labs and is currently being translated to clinical applications in first commercial implementations.
Many (but not all) PA implementations integrate active pulse/echo ultrasound in a hybrid imaging system to capitalize on well-established contrast for anatomical information. The scope of this IOD is the Photoacoustic (PA) image. Complementary images such as pulse/echo ultrasound are represented by their native DICOM IODs. Albeit fusing PA images with US images for display is the presently most common scenario, the particulars of the fusion are beyond the scope of this IOD but examples are provided. PA images represent image output generated by the input of one or more optical excitation wavelengths.

The following items are considered out of scope:
● Photoacoustic specific SR file implementation is reserved for a later supplement.
● If a PA device produces an image with no PA optical image, the SOP class of the structural image (e.g. ultrasound) will be used
● If a PA device creates a single image component by fusing the structural image to the PA image for display as a single image (burned in), it will use the SOP class of the structural image.
● A closely related imaging modality is Thermoacoustic imaging (TAI) which uses microwave radiation to excite the tissue (in contrast to light pulses). The specific characteristics of TAI were not addressed in this particular DRAFT and focus was given to photoacoustic imaging as defined herein, where excitation is limited to pulsed light. Hence, this modality is excluded in this supplement to limit the scope of the present supplement.

All comments should be submitted as soon as possible but NO LATER than 11:59pm US EST on Friday, January 6, 2023.

 Who can comment? All interested persons are invited to comment. Recipients of this solicitation should feel free to forward it to anyone who may be interested in this topic. There is no cost or obligation associated with commenting and DICOM membership is not required to comment. Commenters are requested to include their contact information.
 What will happen to your comments? DICOM Working Group 6 (Base Standard) and DICOM Working Group 34 (Photoacoustic) will review the comments and discuss their resolution. WG-06 is authorized by the DICOM Standard Committee to decide on the technical merits of the comments.
 Instructions for accessing the documents and submitting comments:

1. Download documents from the website (www.dicomstandard.org/comment)

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FTP server (ftp://medical.nema.org/MEDICAL/Dicom/Supps/PC/) under the file names:
 PDF DOCUMENT – sup229_pc_photoacoustic.pdf
 WORD DOCUMENT - sup229_pc_photoacoustic.docx
 PPT OVERVIEW - sup229_pc_photoacoustic.pptx
(To facilitate the readers’ understanding of this new proposed addition to the DICOM Standard, the authors prepared a PowerPoint presentation which describes the technical issues and use cases.)

2. Submit comment(s): Send your comments to Shayna Knazik (This email address is being protected from spambots. You need JavaScript enabled to view it.) via Word Document or free text within your email. Be sure to include the following information:
 Commenter’s name, affiliation, e-mail address.
 Comment – may be a higher-level statement or a detailed technical comment with tables, illustrations, cut-and-paste from the draft, etc.
 Proposed solution – may be a higher-level statement or a marked-up version or new text, tables, illustrations, etc.
 Line numbers associated with your comment(s).