Stray radiation dose reduction using a backscatter shield and a rectangular collimator for a handheld intraoral X-ray unit.

The objective of this study was to study the dose reduction effect on occupational exposure of operators and public exposure other than operators when a backscatter shield and a rectangular collimator are used in conjunction with a handheld intraoral X-ray unit. The occupational exposure was reduced to 40% when the backscatter shield was attached to the cone-tip, to 13% when the rectangular collimator was attached and to 7.7% when the backscatter shield and rectangular collimator were used together. On the other hand, the public exposure was reduced to 20% when the rectangular collimator was attached, but the backscatter shield was not effective in reducing the public exposure. Attaching a backscatter shield is effective in reducing the occupational exposure, and a rectangular aperture is effective in reducing the occupational exposure, as well as the public exposure.

Relationships among hip instability, iliofemoral ligament, and pain in patients with developmental dysplasia of the hip.

BACKGROUND: To evaluate the relationships among hip instability, pain, and morphology of the iliofemoral ligament (ILFL) in patients with developmental dysplasia of the hip (DDH) using ultrasonography (US). METHODS: We reviewed 86 patients (109 hips) with DDH (Group D), 40 patients (46 hips) with borderline hip dysplasia (BDDH) (Group B) and 20 patients (23 hips) without hip pain and bony abnormality (control group). Group D was classified into three subgroups-the severe (group SP), moderate (group MP), and none/mild (group NMP) hip pain groups-using the visual analogue scale (VAS). For evaluating hip instability and ILFL morphology, the distance between the anterior edge of the anterior inferior iliac spine (AIIS) and the horizontal line to the femoral head, and ILFL thickness were measured using US. The difference between the distance in the neutral position and Patrick position was calculated and defined as the femoral head translation distance (FTD). RESULTS: FTD and ILFL thickness in group D were significantly larger than those in the control group and group B (P < 0.05). There was a significant positive correlation between FTD and ILFL thickness in three groups (r = 0.57, P < 0.05; r = 0.55, P < 0.05; r = 0.62, P < 0.05, respectively). FTD and ILFL thickness in group SP were significantly larger than those in group NMP (P < 0.05). FTD and ILFL thickness in group D had significantly negative correlations with the lateral center edge (r = -0.54, P < 0.05; r = -0.40, P < 0.05, respectively) and vertical-center-anterior angle (r = -0.51, P < 0.05; r = -0.43, P < 0.05, respectively). CONCLUSIONS: Acetabular bony deficiency, especially in the anterior and lateral region can result in antero-posterior hip instability, leading to thickened ILFL and hip pain, even in patients with BDDH. These findings may facilitate our understanding and treatment of patients with DDH. When hip instability is suspected, hip US examination may help confirm the diagnosis and assist in providing objective clinical diagnostic evidence.

Preoperative T2 mapping MRI of articular cartilage values predicts postoperative osteoarthritis progression following rotational acetabular osteotomy.

AIMS: Rotational acetabular osteotomy (RAO) has been reported to be effective in improving symptoms and preventing osteoarthritis (OA) progression in patients with mild to severe develomental dysplasia of the hip (DDH). However, some patients develop secondary OA even when the preoperative joint space is normal; determining who will progress to OA is difficult. We evaluated whether the preoperative cartilage condition may predict OA progression following surgery using T2 mapping MRI. METHODS: We reviewed 61 hips with early-stage OA in 61 patients who underwent RAO for DDH. They underwent preoperative and five-year postoperative radiological analysis of the hip. Those with a joint space narrowing of more than 1 mm were considered to have 'OA progression'. Preoperative assessment of articular cartilage was also performed using 3T MRI with the T2 mapping technique. The region of interest was defined as the weightbearing portion of the acetabulum and femoral head. RESULTS: There were 16 patients with postoperative OA progression. The T2 values of the centre to the anterolateral region of the acetabulum and femoral head in the OA progression cases were significantly higher than those in patients without OA progression. The preoperative T2 values in those regions were positively correlated with the narrowed joint space width. The receiver operating characteristic analysis revealed that the T2 value of the central portion in the acetabulum provided excellent discrimination, with OA progression patients having an area under the curve of 0.858. Furthermore, logistic regression analysis showed T2 values of the centre to the acetabulum's anterolateral portion as independent predictors of subsequent OA progression (p < 0.001). CONCLUSION: This was the first study to evaluate the relationship between intra-articular degeneration using T2 mapping MRI and postoperative OA progression. Our findings suggest that preoperative T2 values of the hip can be better prognostic factors for OA progression than radiological measures following RAO. Cite this article: Bone Joint J 2021;103-B(9):1472-1478.

Comparison of air dose and operator exposure from portable X-ray units.

This study was aimed at investigating and comparing exposure dose of workers and the surrounding workers. In addition, worker's exposure was also measure about lens and finger. Four intraoral portable X-ray units were evaluated. The stray radiations were measured using Pitman 37D and ionization chamber (Pitman). MyDosemini (ALOKA) was used for measurement of the finger exposure dose. Without the shield became high in anterior 0.5 m. Comparing the air dose for the four models used in this study showed a high tendency for the two NOMAD models. And using the shields, the images could be taken 4.6 times of the baseline at a maximum and 3.6 times on average. The finger radiation exposure dose was low with both of the NOMAD models, with no significant difference found. By setting the baseline value without a shield, finger radiation exposure when using a shield was lower than the detection limit for the D3000, and was reduced by approximately 94-96% for other three models. All models can photograph around 100 bodies, so it is considered that it is not necessary to switch out the operator considering the operation limit. But even if it does not reach the operation limit, the stochastic effects of radiation exposure can be increased as well as the deterministic effects of the operation limit. The operator and the surrounding workers seek to protect themselves. It is important to perform exposure management that takes into account the stochastic effects to the operator and the surrounding workers.

Factors affecting impingement and dislocation after total hip arthroplasty - Computer simulation analysis.

BACKGROUND: Studies on the causes and factors affecting dislocation after total hip arthroplasty have revealed conflicting results. The purpose of this study was to evaluate the factors affecting impingement and dislocation after total hip arthroplasty, using a 3-dimensional dynamic motion analysis. METHODS: The CT data of 53 patients (53 hips: anterior dislocation; 11 cases, and posterior dislocation; 42 cases) who experienced hip dislocation after total hip arthroplasty with posterior approach, and 120 control patients (120 hips) without dislocation were analyzed. Parameters related to implant alignment, offset and leg length were evaluated. The impingement type was also analyzed using a software. FINDINGS: Considering implant settings affecting dislocation, patients at risk for posterior dislocation had decreased stem anteversion, combined anteversion, femoral offset, and leg length. Nevertheless, patients at risk for anterior dislocation had only lower leg length, and these patients may also be at risk for a higher incidence of recurrent dislocation. Bony impingement occurred in almost half of the cases with posterior dislocation, while implant impingement was associated with anterior dislocation. Importantly, anterior dislocation was not as common as posterior dislocation even in cases with occurrence of posterior impingement. INTERPRETATION: Bony impingement substantially affects dislocation even in the situation where the implant position and alignment are determined by the so-called "safe zone", especially on the anterior side, while implant impingement affects anterior dislocation. The restoration of anterior offset (i.e., prescribed by the stem anteversion and femoral offset) and combined anteversion is critical for avoidance of posterior dislocation after total hip arthroplasty.

Reduction of operator exposure by rectangular collimation in portable intraoral radiography.

Portable intraoral X-ray units are frequently used for home-visit dental treatment and personal dental identification. Therefore, the reduction of operator exposure is crucial. Rectangular collimation is effective at reducing patient exposure and operator exposure; however, its effects are not known. We investigated the reduction of operator exposure through rectangular collimation by measuring the backscattered dose in relation to the operator exposure dose. Using a portable intraoral X-ray unit, a head phantom for CT dose measurement as the object, a dosimeter, and stainless-steel rectangular collimator, a 1-cm ambient dose equivalent was measured in intervals of 15° in horizontal and vertical planes with the radii of 50 and 100 cm. The backscattered dose decreased to approximately one-third when a rectangular collimator was attached to the cone tip. This may have been due to the reduction of the volume of scattered X-rays generated in the phantom by rectangular collimation. We clarified that rectangular collimation is effective at reducing the operator exposure and is useful for protecting the operators of portable intraoral X-ray units during home-visit dental treatment and personal dental identification.

Intra-articular pathology affects outcomes after joint preserving surgery for osteonecrosis of the femoral head.

PURPOSE: Currently, knowledge regarding the intra-articular pathology and its relationship to outcomes after joint-preserving surgery in patients with osteonecrosis of the femoral head (ONFH) is lacking. The purposes were to evaluate the intra-articular pathology and its relationship with outcomes of joint-preserving surgery in ONFH. METHODS: We reviewed 41 hips with ONFH in 41 patients (27 women; mean age, 34.9 years old) who underwent intertrochanteric curved varus osteotomy. Radiographic evaluations were based on pre-operative imaging studies, including radiographs, computed tomography (CT), and magnetic resonance imaging (MRI). Intra-articular pathology was evaluated by arthroscopic inspection of the femoral head, labrum, and acetabular cartilage during surgery. In addition, we performed radiographic measurements of the hip, including the collapse of the femoral head and minimal joint space width at three  years post-operatively and at final follow-up. RESULTS: Arthroscopy revealed damage to the acetabular cartilage and labrum in 22 (54%) and 13 patients (32%), respectively. However, these lesions could be detected on imaging in only 13 (32%) and ten patients (24%), respectively. The change in joint space width after surgery was significantly higher in patients with cartilage degeneration and labral injury (P = 0.02, P = 0.02). Logistic regression analysis for subsequent progression of osteoarthritis showed an association with degenerative changes of articular cartilage and the labral tear as independent predictors (P = 0.001, P = 0.03). CONCLUSIONS: Our data demonstrate the presence of labral and acetabular cartilage lesions in ONFH patients, while images do not reveal the full extent of the tissue damage. These intra-articular pathologies can be associated with the outcomes after joint-preserving surgery.