Fast skin dose estimation system for interventional radiology.

To minimise the radiation dermatitis related to interventional radiology (IR), rapid and accurate dose estimation has been sought for all procedures. We propose a technique for estimating the patient skin dose rapidly and accurately using Monte Carlo (MC) simulation with a graphical processing unit (GPU, GTX 1080; Nvidia Corp.). The skin dose distribution is simulated based on an individual patient's computed tomography (CT) dataset for fluoroscopic conditions after the CT dataset has been segmented into air, water and bone based on pixel values. The skin is assumed to be one layer at the outer surface of the body. Fluoroscopic conditions are obtained from a log file of a fluoroscopic examination. Estimating the absorbed skin dose distribution requires calibration of the dose simulated by our system. For this purpose, a linear function was used to approximate the relation between the simulated dose and the measured dose using radiophotoluminescence (RPL) glass dosimeters in a water-equivalent phantom. Differences of maximum skin dose between our system and the Particle and Heavy Ion Transport code System (PHITS) were as high as 6.1%. The relative statistical error (2 σ) for the simulated dose obtained using our system was ≤3.5%. Using a GPU, the simulation on the chest CT dataset aiming at the heart was within 3.49 s on average: the GPU is 122 times faster than a CPU (Core i7-7700K; Intel Corp.). Our system (using the GPU, the log file, and the CT dataset) estimated the skin dose more rapidly and more accurately than conventional methods.

[Trial manufacture of subsidiary tool and use of technique for shoulder joint of "Scapula Y"].

The technique of "Scapula Y " is effective for capturing forward/backward dislocation of the humeral head and variation in surgical spine fracture. It is also indispensable for describing images of ossification at the tendon plate of the lower lobe of the acrominon and impingement syndrome. However, owing to large individual variations in body shape and position and shape of the scapula, the conventional method does not lend itself to stable reproduction of position or provide adequate diagnostic information. We measured the central angle of entry from scapula m24 pairs of dried bone (Indian) into the spine of the scapula from horizontal and forehead planes to determine the range of variation together with the clinical data referred to in the next paragraph. We then manufactured a trial subsidiary tool to set the angle of the central entering beam base on the acrominon to the spine of the scapula using data on measured angle from 50 clinical radiographs. We identified improvement in radiography of the scapula by using the subsidiary tool designed and manufactured on the basis of the above measured data.