Effective radiation dose in radiostereometric analysis of the hip

Abstract

Background and purpose — Radiostereometric analysis (RSA) is the gold standard to study micromotion of joint replacements. RSA requires the acquisition of additional radiographs increasing the radiation dose of patients included in RSA studies. It is important to keep this dose as low as possible. Effective radiation dose (ED) measurements of RSA radiographs for different joints were done by Teeuwisse et al. some years ago using conventional radiology (CR); for total hip arthroplasty (THA), Teeuwisse et al. reported an ED of 0.150 milliSievert (mSv). With the modern digital radiography (DR) roentgen technique the ED is expected to be less. Material and methods — In this phantom study, simulating a standard patient, the ED for hip RSA radiographs is determined using DR under a variety of different roentgen techniques. The quality of the RSA radiographs was assessed for feasibility in migration analysis using a (semi-)automatic RSA analysis technique in RSA software. Results — A roentgen technique of 90 kV and 12.5 mAs with additional 0.2 copper (Cu) + 1 mm aluminum (Al) external tube filters results in an ED of 0.043 mSv and radiographs suitable for analysis in RSA software. Interpretation — The accumulated ED for a standard patient in a 2-year clinical hip RSA study with 5 follow-up moments and a double acquisition is below the acceptable threshold of 1.0 mSv provided by the EU radiation guideline for studies increasing knowledge for general health.

Precision of CT-based micromotion analysis is comparable to radiostereometry for early migration measurements in cemented acetabular cups

“…In a study by Blom et al. ( 2020 ), the effective dose of RSA was estimated to be 0.04 mSv, similar to our findings. The complexity of acquiring RSA images where patient and calibration cage are lined up correctly means that some additional retakes of RSA images could increase the effective dose for RSA.…”

Precision of low-dose CT-based micromotion analysis technique for the assessment of early acetabular cup migration compared with gold standard RSA: a prospective study of 30 patients up to 1 year

“…Even though the effective radiation dose for a CT examination is higher than that for RSA, we reckon that the advantages of the CT-based method outweigh this fact. According to our data, CTMA could be considered as an alternative to RSA in studying proximal cup migration, although, in order to achieve acceptable radiation dose for patients in a long-term follow-up migration study, further optimization of CT-scan protocols and adjustment of radiation dose is necessary to reduce the radiation exposure (43).…”

Computed tomography-based radiostereometric analysis in orthopedic research: practical guidelines

“…This is a large step down from the 3-5 mSv reported for normal-dose hip CT [12]. For comparison, RSA examinations based on conventional radiography have reported a radiation dose for hip at around 0.05-0.15 mSv [13][14][15]. A given amount of radiation has a lower biological effect in extremities such as knee, wrist, or foot than for example hip, spine, and shoulder.…”