Management of radiation dosage through use of multiple functions of the device

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The following case was submitted by a participant for Radiographer of the year 2017 contest sharing his best practices for radiation dose management.

Describe your focus of study


This study aims to demonstrate management of radiation dosage through use of multiple functions of the device. By selecting the “Fluoroscopy save,” option in the image acquisition method during angiography then reversing the output, the DSFS (digital subtraction fluoroscopy save) image can be acquired, which is as efficient as the DSA (digital subtraction angiography) - but with reduced radiation and frame rate
 

Indicate the purpose and objective of the case

Proper use of the “fluoroscopy save,” option allows for the DSFS to be substituted for cases requiring hand injection DSA images or upper/lower extremity angiography to ultimately allow efficient control over patients’ and operators’ radiation dosage.

Provide brief clinical and patient background
 

"To best replicate a real clinical situation where a dye is injected into the patient, RANDO Phantom and vessel models were used. A polyvinyl chloride tube was curved to represent the vessel, which was placed inside an acryl box (3mm) with an entry and an exit site for the dye. The Phantom was placed above the box to commence the experiment. The device model used was fluoroscopic equipment, with the table height set at 85cm, SID 110, and FD size 48. The lower body x-ray shield was installed at the table and the glass dosimeter was attached at 2 points: surface of the phantom for surface dose and the location of the operator for neighboring dose, with the detector 1cm away. An auto-injector was used to administer 20mL of the dye at 1mL/sec, with the image acquired through both DSA (hand injection, 1 frame/sec) and DSFS.

 

Since 2015, over 50 patients have been treated with the above method, with clinical results showing better quality images for both low BMI patients and upper/lower extremity procedures, regardless of sex."

By selecting the fluoroscopy save option in the image acquisition method during angiography then reversing the output, the DSFS (digital subtraction fluoroscopy save) image can be acquired, which is as efficient as the DSA (digital subtraction angiography) - but with managed radiation and higher frame rate”.

Describe the dose management methods/techniques used


Prior to dye injection, “fluoroscopy save,” option was used to acquire images, after which the output was reversed to get the DSA image. This method was applied to phrenic artery angiography (which requires many hand injection angiography procedures) and upper/lower extremity procedures (PTA, stent insertion, diagnosis since these images can be acquired even with low dose radiation). The results showed no issues with treatment or clinical outcome of patients, but high BMI patients were excluded for phrenic artery angiography due to low quality images.

 

Explain the results and conclusions reached
 

On average, the surface dose was managed from 4122.67μGy to 857μGy, the neighboring dose from 117μGy to 23.67μGy. Independent t-test was completed through SPSS (version 18; PASW statistics), with the analysis showing significant difference (p<0.001).

 

Discuss the case outcome(s), future implications, etc.
 

Compared to the DSA, DSFS allows image acquisition with reduced radiation dose, and a higher frame rate useful for capturing branching of the vessels. However, the image quality can vary, and thus the method is limited to certain locations in the body as well as the body type; thus the method is useful for parts of the body with thin layers of fat, or specific anatomy such as upper/lower extremities. Furthermore, SMART MASK can be used in conjunction with DSFS, but is currently not recommendable because the images display the vessels and device too dark. If this problem can be remedied, further reduction in radiation would be possible without compromise of patients’ health.

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