Radiology

Author(s):  
Luke Cascarini ◽  
Clare Schilling ◽  
Ben Gurney ◽  
Peter Brennan

This chapter discusses radiology in oral and maxillofacial surgery, including Guidelines for dental radiology, Dental radiography, Panoramic radiography, Ultrasonography, Computed Tomography (CT), Cone beam CT, Magnetic Resonance Imaging (MRI), Nuclear medicine imaging and Sialography

Author(s):  
Nguyen Tuong Pham

Mục tiêu: Đánh giá vai trò của cộng hưởng từ (Magnetic Resonance Imaging - MRI) trong mô phỏng lập kế hoạch xạ trị cho bệnh lý u não tại Bệnh viện Trung Ương Huế, đánh giá sự tối ưu, lợi ích của vai trò MRI, các giá trị liều lượng mà u và các cơ quan lành nhận được. Đối tượng và phương pháp: Nghiên cứu 38 bệnh nhân u não được chỉ định xạ trị có chụp cắt lớp vi tính (Computed Tomography-CT) 16 lát cắt Philips và cộng hưởng từ(MRI) 1.5 Tesla Philips tại Trung tâm Ung bướu - Bệnh viện Trung Ương Huế từ tháng 01/2018-07/2019. Lập kế hoạch xạ trị gia tốc bằng phần mềm XiO 5.10 đối với kỹ thuật xạ trị 3D-CRT (Three Dimensional - Conformal Radiation Therapy), và phần mềm Monaco 5.11 đối với các kỹ thuật xạ trị hình cung điều biến liều theo thể tích khối u (Volumetric Modulated Arc Therapy-VMAT), Xạ phẫu gồm SRS và SRT (Stereotactic radiosurgery, Stereotactic radiotherapy). Chụp Cone beam CT kiểm tra trước khi điều trị bởi thiết bị hướng dẫn hình ảnh XVI. Điều trị trên máy gia tốc AXESSE (Elekta). Kết quả và bàn luận: 38 bệnh nhân có khối u ở não (u nguyên phát và u di căn) MRI giúp phát hiện thêm các tổn thương 39,5% và 55,3% phát hiện rõ ranh giới u, tất cả những thương tổn u mà CT rất khó phân biệt với mô lành và tổn thương phù não. Kết luận: Ứng dụng hình ảnh MRI trong mô phỏng lập kế hoạch xạ trị gia tốc cho các bệnh lý u não giúp phát hiện và xác định kích thước, thể tích u tốt hơn so với CT mô phỏng. Từ đó sẽ làm thay đổi kế hoạch xạ trị đem lại kết quả điều trị tốt hơn và cải thiện chất lượng sống tốt hơn cho bệnh nhân


2021 ◽  
Author(s):  
Michael H. Wang ◽  
Anthony Kim ◽  
Mark Ruschin ◽  
Hendrick Tan ◽  
Hany Soliman ◽  
...  

Abstract Background Magnetic Resonance Imaging (MRI)-Linear Accelerator (MR-Linac) radiotherapy requires special consideration for secondary electron interactions within the magnetic field, which can alter dose deposition at air-tissue interfaces. Methods Thirty-seven consecutive glioma patients treated during their radiotherapy course with at least one fraction delivered on MR-Linac or Cone Beam CT (CBCT)-guided Linac, were analyzed. Treatment planning for both systems were completed prior to radiotherapy initiation and approved for clinical delivery using commercial treatment planning systems (TPS): a Monte Carlo calculation-based or convolution calculation-based TPS for MR-Linac or CBCT-Linac, respectively. Dosimetric parameters for planning target volume (PTV), organs-at-risk (OARs), and air-tissue interface were compared. In vivo skin dose during a single fraction of MR-Linac and CBCT-Linac treatment was measured using an Optically Stimulated Luminescent Dosimeter (OSLD) and correlated with TPS skin dose. Results Monte Carlo-based MR-Linac plans and convolution-based CBCT-Linac plans exhibited minimal differences in PTV and OAR parameters. However, MR-Linac plans had greater doses within tissues surrounding air cavities (1.52 Gy higher mean Dmean, p < 0.0001) and skin (1.10 Gy higher mean Dmean, p < 0.0001). In vivo OSLD skin readings were 14.5% greater for MR-Linac treatments (p = 0.0027), and were more accurately predicted by Monte Carlo-based calculation (ρ = 0.95, p < 0.0001) vs. convolution-based (ρ = 0.80, p = 0.0096). Conclusions The magnetic field’s dosimetric impact was minimal for PTV and OARs in glioma as compared to standard CBCT-Linac treatment plans. However, skin doses were significantly greater with the MR-Linac and correlated with in vivo measurements. Future MR-Linac planning processes are being designed to account for skin dosimetry and treatment delivery.


2017 ◽  
Vol 14 (3) ◽  
pp. 69-74
Author(s):  
Elżbieta Czajka

Wykorzystanie rezonansu magnetycznego (ang. magnetic resonance imaging, MRI) w radioterapii jest często poruszanym zagadnieniem w ostatnich latach. Osobny blok wystąpień poświęcony temu tematowi pojawił się również w części programu dedykowanej elektroradiologom na 3rd ESTRO FORUM. Podczas wystąpień omówiono trzy obszary, w których możliwe jest wykorzystanie rezonansu magnetycznego w radioterapii, tj. 1) akwizycja obrazów niezbędnych do planowania leczenia 2) planowanie leczenia w systemie komputerowym w oparciu o obrazowanie rezonansem magnetycznym oraz 3) realizacja leczenia na aparacie terapeutycznym. Zastąpienie w łańcuchu terapeutycznym przede wszystkim tomografii komputerowej (ang. computed tomography, CT) ale również w dalszym etapie innych metod obrazowania, wykorzystujących promieniowanie rentgenowskie np. CBCT (ang. cone beam CT), MVCT (ang. mega voltage CT) lub kVCT (ang. kilo voltage CT) rezonansem magnetycznym, wprowadza do radioterapii tzw. „full-MR workflow”, czyli koncepcję radioterapii opartej wyłącznie o obrazowanie rezonansem magnetycznym. Analiza wybranych doniesień ma na celu przybliżenie czytelnikowi tego zagadnienia, omówienie jego zalet i potencjalnych ograniczeń, ale również umiejscowienie elektroradiologia w całym procesie radioterapeutycznym opartym o rezonans magnetyczny.


2021 ◽  
Author(s):  
Michael H. Wang ◽  
Anthony Kim ◽  
Mark Ruschin ◽  
Hendrick Tan ◽  
Hany Soliman ◽  
...  

Abstract Magnetic Resonance Imaging (MRI)-Linear Accelerator (MR-Linac) radiotherapy is an innovative technology that requires special consideration for secondary electron interactions within the magnetic field, which can alter dose deposition at air-tissue interfaces. Thirty-seven consecutive glioma patients had treatment planning completed and approved prior to radiotherapy initiation using commercial treatment planning systems (TPS): a Monte Carlo-based or convolution-based TPS for MR-Linac or Cone Beam CT (CBCT)-guided Linac, respectively. In vivo skin dose was measured using an Optically Stimulated Luminescent Dosimeter (OSLD) and correlated with TPS skin dose. We found that Monte Carlo-based MR-Linac plans and convolution-based CBCT-Linac plans had similar dosimetric parameters for target volumes and organs-at-risk. However, MR-Linac plans had 1.52 Gy higher mean dose to air cavities (p<0.0001) and 1.10 Gy higher mean dose to skin (p<0.0001). In vivo skin dose was 14.5% greater for MR-Linac (p=0.0027), and were more accurately predicted by Monte Carlo-based calculation (ρ=0.95, p<0.0001) vs. convolution-based (ρ=0.80, p=0.0096). This is the first prospective dosimetric comparison of glioma patients clinically treated on both MR-Linac and CBCT-guided Linac. Skin doses were significantly greater with MR-Linac and correlated with in vivo measurements. Future MR-Linac planning processes are being designed to account for skin dosimetry and treatment delivery.


Author(s):  
Luke Cascarini ◽  
Clare Schilling ◽  
Ben Gurney ◽  
Peter Brennan

Guidelines for dental radiology 40 Dental radiography 42 Panoramic radiography 46 Facial and skull radiography 48 Ultrasonography 50 CT and cone beam CT 52 MRI and nuclear imaging 56 Sialography 57 • Although the radiation doses are generally quite low, the same rules apply as with other radiology and are controlled by IRMER (Ionizing Radiation (Medical Exposure) Regulations (2000))....


2016 ◽  
Vol 22 (4) ◽  
pp. 93-96 ◽  
Author(s):  
Osamu Tanaka ◽  
Takayoshi Iida ◽  
Hisao Komeda ◽  
Masayoshi Tamaki ◽  
Kensaku Seike ◽  
...  

Abstract Visualization of markers is critical for imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). However, the size of the marker varies according to the imaging technique. While a large-sized marker is more useful for visualization in MRI, it results in artifacts on CT and causes substantial pain on administration. In contrast, a small-sized marker reduces the artifacts on CT but hampers MRI detection. Herein, we report a new ironcontaining marker and compare its utility with that of non-iron-containing markers. Five patients underwent CT/MRI fusion-based intensity-modulated radiotherapy, and the markers were placed by urologists. A Gold Anchor™ (GA; diameter, 0.28 mm; length, 10 mm) was placed using a 22G needle on the right side of the prostate. A VISICOIL™ (VIS; diameter, 0.35 mm; length, 10 mm) was placed using a 19G needle on the left side. MRI was performed using T2*-weighted imaging. Three observers evaluated and scored the visual qualities of the acquired images. The mean score of visualization was almost identical between the GA and VIS in radiography and cone-beam CT (Novalis Tx). The artifacts in planning CT were slightly larger using the GA than using the VIS. The visualization of the marker on MRI using the GA was superior to that using the VIS. In conclusion, the visualization quality of radiography, conebeam CT, and planning CT was roughly equal between the GA and VIS. However, the GA was more strongly visualized than was the VIS on MRI due to iron containing.


2021 ◽  
Vol 38 (SI-2) ◽  
pp. 104-112
Author(s):  
Emre CESUR ◽  
Kaan ORHAN

The validity of orthodontic diagnosis and treatment planning depends on the accuracy of the photos, models and radiograps to be obtained from the patient. One of the most important parts of diagnosis and treatment planning is the use of appropriate imaging method. Although lateral cephalometric radiographs are still the most preferred imaging method, other methods such as hand-wrist radiographs, panoramic radiographs, cone beam computerized tomography (CBCT), magnetic resonance imaging (MRI), and ultrasound are also frequently used. For this reason, it is important to know the advantages and disadvantages of all imaging methods for orthodontists in order to select the most suitable method for the patient.


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