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Practical Considerations for the Clinical Physicist

J Kavanaugh1*, M Lin2*, E Draeger3*, K Hogstrom4*, C Shi5*, M Chan6*, (1) Washington University in St. Louis, University City, MO, (2) The University of Texas Southwestern Medical Ctr, Dallas, TX, (3) Yale New Haven Hospital, New Haven, CT, (4) Mary Bird Perkins Cancer Center, Baton Rouge, LA, (5) New York Proton Center, Marlbor, NJ, (6) Memorial Sloan Kettering Cancer Center, Basking Ridge, NJ

Presentations

(Saturday, 3/26/2022) 2:00 PM - 4:00 PM [Central Time (GMT-5)]

Room: Celestin D-E

As the complexity of radiotherapy treatment planning increases, the role of the physicist in the assessment of treatment plan quality becomes more critical. The first presentation in this session aims to define what high quality means in radiotherapy treatment planning and the role of the physicist in ensuring high quality treatment plans for all patients. Suggestions for the review of treatment plan quality for clinical physicists, as well as real life examples of “optimal” and “sub-optimal” quality treatment plans will be provided. Recent advancements in data-driven plan quality control and scripting will also be discussed to provide physicists with up-to-date information on how to effectively use these tools for the assessment of treatment plan quality.

Learning Objectives:
1. To define quality in radiotherapy treatment planning, understand the difference between “optimal” and “sub-optimal” quality treatment plans, and understand the role of a physicist in determining the quality of a radiotherapy treatment plan.
2. To discuss how to evaluate the clinical and technical features that affect plan quality such as beam configuration, optimization objectives, and review of isodose distributions.
3. To review examples of sub-optimal quality plans from real clinical cases in order to help participants identify similar quality issues within their own institutions and to summarize and highlight the key aspects of clinical implementation of the current automation/data-driven plan quality control tools.


Skin cancer is one of the most common malignancies in the United States, and affects 2-3 million people each year. Surgery is often considered the standard of care for the treatment of skin cancer, however comorbidities or unacceptable functional and cosmetic outcomes may prohibit patients from surgical treatment. The second and third lectures in this session will focus on different approaches to skin cancer treatment using brachytherapy and electron beam therapy.

Brachytherapy, while generally underutilized for skin treatments, can offer several advantages over EBRT, such as hypofractionated treatments, shorter treatment times, lower doses to surrounding tissues, and excellent cosmetic outcomes. While brachytherapy can offer advantages over EBRT, there are also several unique factors that need to be considered, including smaller target size, limited depth of target, and applicator material composition. This lecture will provide an introduction to when radionuclide-based surface brachytherapy is appropriate for the treatment of skin cancers, which applicators are available for surface treatments, and when model-based dose calculation algorithms are required for treatment planning in brachytherapy.

Electron beam therapy can be useful for treatment of skin cancers within 6 cm of the patient surface. Most treatment planning systems have adequate dose accuracy using fast Monte Carlo (MC) algorithms or the pencil beam redefinition algorithm (PBRA); however, planning software to support current and new delivery technologies is lagging. Machined personal treatment devices such as cutouts, uniform thickness bolus, and variable thickness bolus are currently commercially available with skin collimation and intensity modulators on the horizon. Case studies from head, neck, limbs, and chest wall sites will be reviewed to demonstrate treatment techniques using traditional electron beam therapy, bolus electron conformal therapy (BECT), intensity-modulated BECT, and mixed beam therapy.

Learning Objectives:
1. Understand when brachytherapy is appropriate for the treatment of skin cancer and which brachytherapy applicators are available for skin treatments.
2. Understand the availability of electron beam therapy planning and delivery technology.
3. Understand the utility of electron beam therapy in the head, neck, limbs, and chest wall


Current clinical challenges exist for patients undergoing radiotherapy with various implanted devices used. The final lecture in this session will provide an overview of how to deal with those existing and emerging implanted devices. Commonly present devices in cancer patients include cardiac pacemaker, implanted cardiac defibrillator (ICD), intrahepatic pump, pain pump, neurostimulator, shunt, loop recorder, spine hardware, and medi-port. Three different classifications of implanted devices can be made: life-dependent, non-life-dependent but have adverse effects if overdosed, and devices without electronic circuits. The implications of radiotherapy (both photon and proton-based treatments) for these three classes will be discussed along with current risk-stratification and the corresponding management.

Learning Objectives:
1. To be familiar with the existing and emerging devices inside patients undergoing radiotherapy.
2. To be able to classify implanted devices and appropriately manage the planning and delivery of radiation in patients for photons and protons with specific devices.
3. To provide guidelines for some of the newer implanted devices, such as hepatic pump, infusion pump, intrathecal pain pump, neurostimulator, cerebral shunts, etc.

Handouts

Keywords

Not Applicable / None Entered.

Taxonomy

TH- External Beam- Photons: General (most aspects)

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