## 2 Materials and Methods  
Environmental Dose Rate Measurements During \({}^{99m}\)Tc-MDP Bone Scintigraphy Procedure: Assessment of Radiation Dose in Nuclear Medicine Center Controlled Areas  
Conducting an environmental radiation survey in nuclear medicine center-controlled areas involves structured steps to ensure comprehensive monitoring and safety in environments where radioactive materials are handled. The initial stage of the survey protocol is preparation, which includes selecting and calibrating survey instruments. During a \({}^{99m}\)Tc-MDP bone scintigraphy procedure, a Geiger counter (Ludlum Measurements, Inc., Sweetwater, TX, USA) is used to measure dose rates. Calibration is performed according to the manufacturer's specifications to ensure accuracy. Additionally, a minimum detectable dose rate (MDDR) of 0.1 \(\upmu\)Sv/h is set to maintain sensitivity to low radiation levels, thereby making the survey reliable and precise for controlled-area environments. Following preparation, ambient equivalent dose measurements are taken to establish background radiation levels within each area of interest, including preparation rooms, patient waiting areas, and procedure rooms. These measurements are taken before \({}^{99m}\)Tc-MDP is introduced, providing an apparent reference for subsequent readings during and after the procedure. Establishing baseline readings in each area ensures that any radiation level increases can be accurately assessed against these initial data. Moreover, it reiterates the critical role of baseline measurements, which are critical in nuclear medicine settings where multiple procedures involving radiopharmaceutical may be conducted daily, making it critical to confirm safe background levels before starting each new procedure. During the active phases of the \({}^{99m}\)Tc-MDP procedure, dose rate measurements are conducted at specific intervals across three phases: pre-procedure, intra-procedure, and post-procedure. Pre-procedure ambient dose monitoring involves checking dose rates across all designated areas to confirm that there is no unexpected radiation from previous work and that the environment is safe for the upcoming procedure. The ambient radiation dose measurement, H*(10), was calibrated with \({}^{137}\)Cs (ISO 4037-1), using an ICRU sphere phantom. That effectively approximates the human body as regards the scattering and attenuation of the radiation fields [14]. As the procedure begins, real-time dose rate monitoring is maintained, with strategic measurement points established around high-activity locations, such as near \({}^{99m}\)Tc-MDP radiopharmaceutical preparation and injection sites. Time-stamped readings enable ongoing monitoring throughout the procedure, allowing for the detection of any unexpected radiation increases that might signal contamination or an accidental release. This phase of the survey protocol plays a critical role in ensuring a safe working environment for medical personnel and patients alike. Additionally, on completing the procedure, a post-procedure survey is conducted to verify that ambient dose levels in each area have returned to baseline. This final survey ensures that any residual radiation from the procedure has appropriately decayed or been managed, allowing for safe use of the area afterward. All survey data, including background, intra-procedure, and post-procedure measurements, are thoroughly documented, with time, location, and dose rate details recorded for each measurement. These recorded measurements are then compared with regulatory safety limits, ensuring compliance with local or international guidelines on radiation exposure. Should any measurement exceed safe dose rates, an incident report is generated, and necessary actions--such as area closure or decontamination--are initiated. Post-survey procedures include decontamination if elevated levels persist, followed by additional surveys to confirm the effectiveness of these actions.