ACPSEM position paper on ROMP scope of practice and staffing levels for magnetic resonance linear accelerators.

The purpose of this position paper is to outline the ACPSEM recommendations on Medical Physicist scope of practice and staffing levels, as they relate to the use of dedicated MRI-Linacs in the treatment of patients. A core function of Medical Physicists is to safely implement changes in medical practice via the introduction of new technology and to ensure high quality radiation oncology services are provided to patients. Determining the feasibility of MRI-Linacs in any existing setting, or in establishing a new site, mandates the knowledge and services of Radiation Oncology Medical Physicists (ROMPs) as the Qualified Experts within this setting.

Linac reported steering error insensitive to 6 MV FFF transverse beam position deviations.

Clinically significant beam position deviations were observed for a 6 MV FFF beam during patient specific QA on an Elekta linear accelerator. There was no significant reported transverse steering error from the machine ion chamber, and routine linac QA practices, including cardinal angle Winston-Lutz test, did not identify the deviations. Subsequent investigation using an electronic portal imaging device (EPID) revealed clinically significant beam position deviations for small steering errors.

Optimising treatment distance and treatment area for HDR surface mould brachytherapy.

The purpose of this study was to quantify the effect of treatment area and treatment distance on dose distributions for geometrically optimised surface mould plans in order to provide guidance in choosing treatment parameters and constructing moulds for individual patients. Geometrically optimised plans were generated with a typical brachytherapy planning system and measurements were taken with radiochromic film over depths of 5-32 mm with an (192)Ir high dose rate source. Films were calibrated with a cylindrical geometry technique utilising the (192)Ir source and readout was performed with a flatbed scanner.