The virtual conference, which will take place on 25–29 July 2021, will allow medical physicists from all parts of the world to share ideas and learn about new innovations
This year’s Annual Meeting of the American Association of Physicists in Medicine will exploit a new online platform to enable a global audience of medical physicists to share ideas, interact with colleagues, and learn about innovative products. The virtual meeting will take place on 25–29 July, providing five days of real-time scientific, professional and educational content, while an on-demand option is also available for registrants to catch up on anything they missed during that five-day period.
The theme for this year’s meeting is “Creative science. Advancing medicine”. According to the AAPM president, James T Dobbins III of Duke University, the meeting will explore the ways in which medical physicists can use their creativity and scientific expertise to build the clinical practice of the future. The Presidential Symposium will focus on the topic of creativity in science, and Dobbins says that the meeting sessions “will explore our roles as scientific innovators in both research and the clinic”.
Once again the meeting will feature a virtual exhibit hall, which proved to be a real success in 2020. Included in the conference programme is a track of vendor showcases, which enable companies to host demonstrations of their latest products. Delegates can also interact with a selection of vendors through a series of “Partners in Solutions” sessions, which are designed to provide clinical physicists with practical information on using specific systems.
Meanwhile, exhibitors have the opportunity to host guided tours of their virtual booth to highlight products designed to address specific clinical needs, as chosen by the organizing committee. Some of the innovations that vendors will be introducing, particularly for fast and accurate quality assurance (QA), are highlighted below.
Zeus phantom puts MR-guided linacs to the test
The Zeus phantom from CIRS combines an MR-safe motion-control platform with an MR-realistic body to provide complete end-to-end testing of MR-guided linac systems such as ViewRay’s MRIdian and Elekta’s Unity.
The phantom’s gel-filled body contains anthropomorphic lungs, liver, kidney and spine with a life-like shape and spatial relationship, and offers imaging contrast in both MR and CT. MR-safe piezoelectric motors move a cylindrical insert with an organic-shaped tumour through the phantom body in three dimensions. All organs except for the lungs offer ion-chamber dosimetry cavities for completing an entire QA process.
The phantom is equipped with motion-control software that includes multiple built-in profiles for use during commissioning and for routine QA. It also allows patient-specific respiratory waveforms to be imported and, if needed, to be edited for amplitude, sample rate, cycle time, phase shift and baseline position.
The software allows users to set up independently controllable waveforms for both linear and rotational motion of the insert, while the inferior–superior motion of the insert or moving target can be gated based on amplitude to verify the beam latency of the machine. Finally, a physical interface for the beam-on/beam-off signal can be read by the motion control software to calculate the beam latency specific to hybrid MR-linac systems.
3D measurement of MR image distortion achieves sub-millimetre precision
A new distortion-analysis system from Modus QA offers a lighter, larger and more efficient way to quantify the geometric distortions in MR imaging in three dimensions. Measuring these distortions and establishing accepted thresholds is crucial for achieving accuracy in MR-guided radiotherapy treatments, and the QUASAR MRID3D delivers sub-millimetre accuracy for commissioning and continuous QA of MR-guided systems.
An efficient workflow is enabled by a hollow-boundary phantom design with a large field of view (37 x 32 cm2), which allows set-up, scan and analysis in less than 10 minutes. In addition to automated distortion quantification, the phantom software also offers advanced features to correct any errors that arise from phantom susceptibility distortions, the spherical harmonics coefficient output, any rotation or movement of the patient table, and inhomogeneities in the magnetic field and the gradient nonlinearity. Image analysis software provides a built-in 3D DICOM viewer and region-of-interest selector, allowing users to analyse smaller custom volumes.
Modus QA has released a white paper that reviews the factors that affect MRI geometric image distortion, as well as the tools that can be used to quantify it. It also explores the spherical harmonic analysis approach exploited in the QUASAR MRID3D, and presents the recommended method for measuring a full 3D distortion vector field with this large field-of-view phantom.
Updated software expands capabilities for machine QA
Sun Nuclear’s SunCHECK platform, which is widely used to standardize both machine QA and patient QA among staff, sites and equipment, offers more than 50 feature enhancements in its latest release. Among other things, version 3.2 of the software improves task and template customization, expands support for imaging tasks, and makes it easier to share templates.
Sun Nuclear will be showcasing the latest capabilities of the SunCHECK platform in a vendor showcase session during AAPM (10.30 am EDT, Wednesday 28 July).
The company is also releasing a new version of its SNC Patient software, which is designed to provide efficient, device-specific workflows for clinical users. Version 8.5 enables SRS MapCHECK, Sun Nuclear’s film-less solution for stereotactic patient QA, to support machine QA for the CyberKnife system – which makes SRS MapCHECK the only device that offers both machine QA and patient QA on a CyberKnife.
Other new capabilities include QA for multileaf collimators, iris beams and targeting accuracy, while the new release also extends compatibility for a range of Varian and Accuray treatment delivery systems.
Another vendor showcase by Sun Nuclear offers a preview of the new features now included in SNC Patient software (10.30 am EDT, Monday 26 July).
Digital QA solution delivers speed and film-class resolution for stereotactic treatments
IBA Dosimetry will be introducing a fully digital solution for high-resolution QA for both stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). The myQA SRS system features a digital detector array for faster QA, and also achieves a film-class resolution of 0.4 mm. With an active detector area measuring 12×14 cm2, the solution offers more than 100,000 measurement pixels, while zero pixel spacing avoids the need for interpolation. The plan delivery and validation are completed in just a few minutes, making myQA SRS as efficient as any routine QA.
“The digital detector QA workflow with myQA SRS is 106 times faster and easier compared to using film,” comments Yun Yang of Rhode Island Hospital in the US, who has tested the solution in a clinical setting. “The film-equivalent resolution for our QA measurements is the basis for better and more meaningful SRS patient plan verification with a high sensitivity and specificity to detect the real dose errors.” Yang will share his results in an AAPM presentation and a webinar that is available on the IBA Dosimetry website.
IBA Dosimetry will also be showcasing myQA iON, a software environment that combines all patient QA tasks and workflow steps in a single interface. The software allows irradiation log files and dose measurements to be used alongside Monte Carlo prediction techniques, allowing the dose profile to be recalculated with fewer measurements and greater accuracy.