Michael Roumeliotis

A framework for clinical commissioning of 3D‐printed patient support or immobilization devices in photon radiotherapy

Abstract Purpose The objective of this work is to outline a framework for dosimetric characterization that will comprehensively detail the clinical commissioning steps for 3D‐printed materials applied as patient support or immobilization devices in photon radiotherapy. The complex nature of 3D‐printed materials with application to patient‐specific configurations requires careful consideration. The framework presented is generalizable to any 3D‐printed object where the infill and shell combinations are unknown. Methods A representative cylinder and wedge were used as test objects to characterize devices that may be printed of unknown, patient‐specific dimensions. A case study of a 3D‐printed CSI immobilization board was presented as an example of an object of known, but adaptable dimensions and proprietary material composition. A series of measurements were performed to characterize the materials kV radiologic properties, MV attenuation measurements and calculations, energy spectrum water equivalency, and surface dose measurements. These measurements complement the recommendations of the AAPMs TG176 to characterize the additional complexity of 3D‐printed materials for use in a clinical radiotherapy environment. Results The dosimetric characterization of 3D‐printed test objects and a case study device informed the development of a step‐by‐step template that can easily be followed by clinicians to accurately and safely utilize 3D‐printed materials as patient‐specific support or immobilization devices. Conclusions A series of steps is outlined to provide a formulaic approach to clinically commission 3D‐printed materials that may possess varying material composition, infill patterns, and patient‐specific dimensions.

Including internal mammary lymph nodes in radiation therapy for synchronous bilateral breast cancer: an international survey of treatment technique and clinical priorities

PurposeThe aim of this study was to understand the international standard practice for radiation therapy treatment techniques and clinical priorities for institutions including the internal mammary lymph nodes (IMLNs) in the target volume for patients with synchronous bilateral breast cancer.MethodsAn international survey was developed to include questions that would provide awareness of favored treatment techniques, treatment planning and delivery resource requirements, and the clinical priorities that may lead to the utilization of preferred treatment techniques.ResultsOf the 135 respondents, 82 indicated that IMLNs are regularly included in the target volume for radiation therapy (IMLN-inclusion) when the patient is otherwise generally indicated for regional nodal irradiation. Of the 82 respondents that regularly include IMLNs, five were removed as those respondents do not treat this population synchronously. Of the 77 respondents, institutional standard of care varied significantly, though VMAT (34%) and combined static photon and electron fields (21%) were the most commonly utilized techniques. Respondents did preferentially select target volume coverage (70%) as the most important clinical priority, followed by normal tissue sparing (25%).ConclusionThe results of the survey indicate that the IMLN-inclusion for radiation therapy has not yet been comprehensively adopted. As well, no consensus on best practice for radiation therapy treatment techniques has been reached.

Five-field IMRT class solutions and dosimetric planning guidelines for implementing accelerated partial breast irradiation

PURPOSE A comprehensive set of planning guidelines was developed to aid in achieving reproducible dosimetric results for external beam accelerated partial breast irradiation (APBI). The methodology for the development of class solutions for dosimetric planning of the APBI technique, including dose constraint recommendations, is presented for target coverage and conformity as well as normal tissues. METHODS AND MATERIALS A conservative patient setup was simulated on a linear accelerator, and a comprehensive arrangement of gantry and couch angles was measured for clearance. This provided the foundation for available beam arrangements to develop reproducible and conformal 5-field intensity modulated radiation therapy partial breast plans. Forty patients were planned. Patient plans were assessed according to anatomy specific features, such as laterality and seroma location within the breast. RESULTS Clearance tables are presented to give permissible gantry and couch orientations according to measurements facilitated by patient simulation. Beam arrangement class solutions are presented for left- and right-sided APBI patients. Dosimetric recommendations are made based on the results of 40 patient plans. The median and range, describing target coverage and target conformity, are reported, as are normal tissue constraints for ipsilateral lung, ipsilateral breast, heart, liver, and contralateral breast. In all cases, the dose recommendations were at least as strict as multi-institutional APBI trials. In the case of ipsilateral lung and ipsilateral breast, the planning recommendations are more stringent. CONCLUSIONS APBI using a 5-field intensity modulated radiation therapy technique was comprehensively developed and evaluated to provide recommendations yielding highly conformal and reproducible treatment plans. This provides a clear method to implement external beam APBI planning and delivery.