Suboptimal patient positioning with panoramic and cone beam computed tomography (CBCT) imaging: effects on dose

IF 1.9 3区医学 Q2 DENTISTRY, ORAL SURGERY & MEDICINE Oral Surgery Oral Medicine Oral Pathology Oral Radiology Pub Date : 2025-03-01 Epub Date: 2025-02-04 DOI:10.1016/j.oooo.2024.11.017

Dr. Colin LaPrade , Prof. Brandon Johnson , Dr. Angela Broome , Dr. André Mol , Dr. Marija Ivanovic , Dr. John Ludlow

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Abstract

Objective

The aim of this study is to examine the effects of various changes in patient positioning on radiation exposure for panoramic and cone beam computed tomography (CBCT) extraoral radiographic examinations. Specific objectives include measuring equivalent and effective dose by means of radiation dosimetry with a tissue-equivalent phantom for each modality, with intentional changes in position to the craniofacial complex.

Study Design

Simulated panoramic and CBCT radiographic examinations at optimal positioning in addition to 6 suboptimal positions—anterior, posterior, and lateral shifts by 1 cm; and neck extension (i.e., chin tilted up), flexion (i.e., chin tiled down), and rotation by 10 degrees—were completed using an adult tissue-equivalent phantom. Dosimetry was acquired using optically stimulated luminescence dosimeters placed at 24 anatomical sites in the head/neck region. Exposures were made with the RayScan Alpha Plus x-ray unit using the following exposure parameters for panoramic imaging: 13.9 seconds, 80 kVp, 14 mA; and for CBCT: 14.0 seconds, 90 kVp, 11 mA. Five CBCT and 10 panoramic exposures, respectively, were made to ensure adequate exposure to all sites of interest.

Results

No increases in E were determined for suboptimal panoramic conditions. E for anterior shift (26.9 μSv) and posterior shift (28.1 μSv) demonstrated statistically-significant decreases (P < .001) when compared with optimal positioning (50.0 μSv). For CBCT, no statistically significant changes for E were determined, although equivalent thyroid dose was significantly increased (P = .003) when the chin was titled down (1882.7 μSv) in comparison with optimal positioning (1674.4 μSv).

Conclusions

No suboptimal positions resulted in significant increases in E for either CBCT or panoramic imaging. Initial results suggest that tilting the chin down may increase exposure to the thyroid gland for CBCT imaging. Additional exposures at smaller fields of view are warranted, in addition to exposures with a stabilized thyroid gland position.

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全景和锥束计算机断层扫描（CBCT）成像的次优患者体位：对剂量的影响

目的探讨患者体位的不同变化对全景和锥形束计算机断层（CBCT）口外放射检查中辐射暴露的影响。具体目标包括通过使用组织等效模体的辐射剂量测定法测量等效剂量和有效剂量，并有意改变颅面复合体的位置。研究设计：模拟最佳体位的全景和CBCT放射检查，以及6个次优体位——前、后、侧移1厘米；颈部伸展（即下巴向上倾斜）、屈曲（即下巴向下倾斜）和旋转10度——使用成人组织等效的假体完成。使用放置在头颈部24个解剖部位的光刺激发光剂量计进行剂量测定。使用RayScan Alpha Plus x射线单元进行曝光，全景成像的曝光参数如下：13.9秒，80 kVp, 14 mA；CBCT: 14.0秒，90 kVp, 11 mA。分别进行了5次CBCT和10次全景曝光，以确保对所有感兴趣的地点进行充分曝光。结果在次优全景条件下，E值没有增加。前移（26.9 μSv）和后移（28.1 μSv）的E值均有统计学意义的降低(P <；.001)，与最佳定位（50.0 μSv）比较。对于CBCT，虽然当下巴下移（1882.7 μSv）比最佳位置（1674.4 μSv）时甲状腺当量剂量显著增加（P = .003），但E没有统计学意义上的变化。结论无论是CBCT还是全景成像，不存在次优位置导致E显著增加的情况。初步结果表明，下巴向下倾斜可能会增加CBCT成像时对甲状腺的暴露。除了甲状腺位置稳定外，还需要在较小的视野范围内进行额外的照射。

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来源期刊

Oral Surgery Oral Medicine Oral Pathology Oral Radiology DENTISTRY, ORAL SURGERY & MEDICINE-

CiteScore

3.80

自引率

6.90%

发文量

1217

审稿时长

2-4 weeks

期刊介绍： Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology is required reading for anyone in the fields of oral surgery, oral medicine, oral pathology, oral radiology or advanced general practice dentistry. It is the only major dental journal that provides a practical and complete overview of the medical and surgical techniques of dental practice in four areas. Topics covered include such current issues as dental implants, treatment of HIV-infected patients, and evaluation and treatment of TMJ disorders. The official publication for nine societies, the Journal is recommended for initial purchase in the Brandon Hill study, Selected List of Books and Journals for the Small Medical Library.