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The whole body retention ofcobalt after intravenous injection of carrier-free 58C0Cl, in saline solution has been measured in 16 men. The retention data for each subject have been analysed statistically and the best descriptions of the data are provided by equations with five exponential terms. Investigation levels for the radioisotopes of cobalt have been calculated for each subject. The average investigation level for G°CoCl, computed from the data is an uptake of 1.2 pCi, which may be compared with the value of 24 pCi given in ICRP Publication 10. The coefficient of variation of the radiation dose to various members of the working population after a given uptake of radiocobalt was estimated to be 20%.

Purpose: Assessment of a clinical method that insures a uniform junction when treating four field breast cases on Elekta Synergy linacs outfitted with the new Agility 160 leaf multileaf collimator. Methods: Numerous breast patient step‐and‐shoot plans were generated using Philips Pinnacle3 treatment planning system. Calculated doses were compared with measurements done using Gafchromic EBT3 film inserted in a plastic water phantom.The linac beam spot position was measured according to one of the recently published methods by Balazs et al. (2012). The jaws and MLC leaves were calibrated using the portal imager following the calibration workflow integrated into the linac console. The resulting junction was evaluated using two half blocked fields on XV film at gantry 0°. Results: Initial measurements showed slight variations in beam spot position between all three linacs. These variations were the main factor causing inconsistent and cold junctions. The beam spot adjustment followed by the collimator calibration workflow improved field junctions on the XV film to within tolerance for all linacs.Patient plans in 3 showed that a beam overlap was needed to achieve adequate coverage of the treatment region on the CT slices located close to the junction. In order to avoid overlapping fields at the skin, only the external tangent and the posterior field were overlapped.Gafchromic film measurements showed that a 2 mm beam overlap for a minimum of 5% of the monitor units of both overlapping beams was required to produce a uniform junction within 5% of Pinnacle3 dose calculation. Conclusion: In order to achieve a uniform junction, fine tuning of the beam spot position was necessary. A dosimetric method was developed to achieve uniform dose distribution in the junction area when treating four field breast cases on an Elekta Synergy linac with the new Agility 160 leaf multileaf collimator.

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Purpose: Development of an adapted multidisciplinary procedure designed to optimize the clinical workflow between radiation therapy (RT) and nuclear medicine (NM) for a PET‐CT located in the NM department. Methods : The radiation oncologist (RO) prescribes the PET‐CT exam and the clinical RT therapist gives all the necessary information to the patient prior to the exam. The immobilization accessories are prepared in the RT department. The RT and NM therapists work together for radiotracer injection, patient positioning and scan acquisition. The nuclear medicine physician (NMP) will study the images, draw Biological Target Volumes (BTVs) and produce a full exam report. Results : All tasks related to a planning PET‐CT are done within 48 hours from the request by the RO to the reception of the images with the NMP contours and report. Conclusions : By developing a complete procedure collectively between the RT and NM departments, the patient benefits of a quick access to a RT planning PET‐CT exam including the active involvement of every medical practitioners in these fields.