• Progress in Medical Physics
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• v.24 no.4
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• pp.205-212
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• 2013

Recent developments of image guided radiation therapy (IGRT), especially the On Board Imaging (OBI) system and the cone beam CT (CBCT), enable the radiation treatment more accurate and reliable. IGRT is widely used in the radiation therapy as a standard of care. Use of IGRT is even expected to increase in the near future. IGRT is only beneficial to patients when it is used with proper considerations of safety and appropriateness of the techniques. Institutional procedure should be developed based on the clinical need and the deep understanding of the system before applying the new technique to the clinic. Comprehensive QA program should be established before to the clinic and imaging dose should be considered when preparing the departmental practice guidelines for IGRT.

• Radiation Oncology Journal
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• v.33 no.3
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• pp.161-171
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• 2015

Image-guided radiation therapy (IGRT) is a process of incorporating imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), Positron emission tomography (PET), and ultrasound (US) during radiation therapy (RT) to improve treatment accuracy. It allows real-time or near real-time visualization of anatomical information to ensure that the target is in its position as planned. In addition, changes in tumor volume and location due to organ motion during treatment can be also compensated. IGRT has been gaining popularity and acceptance rapidly in RT over the past 10 years, and many published data have been reported on prostate, bladder, head and neck, and gastrointestinal cancers. However, the role of IGRT in lymphoma management is not well defined as there are only very limited published data currently available. The scope of this paper is to review the current use of IGRT in the management of lymphoma. The technical and clinical aspects of IGRT, lymphoma imaging studies, the current role of IGRT in lymphoma management and future directions will be discussed.

• Progress in Medical Physics
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• v.17 no.4
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• pp.207-211
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• 2006

The advent of kV cone-beam computed tomography (CBCT) integrated with a linear accelerator allows for more accurate Image-guided radiotherapy (IGRT). IGRT is the technique that corrects target displacement based on internal body information. To do this, the CBCT Image set is acquired just before the beam is delivered and registered with the simulation CT Image set. In this study, we compare the registration results according to the CBCT's reconstruction quality (either high or medium). A total of 56 CBCT projection data from 6 patients were analyzed. The translation vector differences were within 1 mm in all but 3 cases. For rotation displacement difference, components of all three axes were considered and 3 out of 168 ($56{\times}3$ axes) cases showed more than lo of rotation differences.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.75-81
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• 2016

The recent radiation therapy field can provide treatment which guarantees a high degree of accuracy, due to patient set-up using various image guided radiation therapy(IGRT) instruments. But the additional absorbed dose to patient's normal tissues is increasing. Therefore, this study measured the absorbed dose to surrounding normal tissues which is caused by patient set-up using OBI, CBCT, ExacTrac, among various IGRT instruments. The absorbed dose to the head, the chest, the abdomen, and the pelvis from CBCT was 12.57 mGy, 20.82 mGy, 82.93 mGy, and 52.70 mGy, respectively. Also, the absorbed dose from OBI and ExacTrac ranged from 0.76 to 8.58 mGy and from 0.14 to 0.63 mGy, respectively. As a result, CBCT's absorbed dose was far higher than other instruments. CBCT's surface dose was far higher than others, too, but OBI's entrance skin dose was almost the same as CBCT's.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.109-116
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• 2021

Purpose: The purpose of this study is to evaluate the usefulness of Surface-Guided Patient Setup by comparing the patient positioning accuracy when image-guided radiation therapy was used for Markerless patients(unmarked on the skin) using Surface-Guided Patient Setup and Marker patients(marked on the skin) using Laser-Based Patient Setup. Materials And Methods: The position error during IGRT was compared between a Markerless patient initially set up with SGPS using an optical surface scanning system using three cameras and a Marker patient initially set up with LBPS that aligns the laser with the marker drawn on the patient's skin. Both SGPS and LBPS were performed on 20 prostate cancer patients and 10 Stereotactic Radiation Surgery patients, respectively, and SGPS was performed on an additional 60 breast cancer patients. All were performed IGRT using CBCT or OBI. Position error of 6 degrees of freedom was obtained using Auto-Matching System, and comparison and analysis were performed using Offline-Review in the treatment planning system. Result: The difference between the root mean square (RMS) of SGPS and LBPS in prostate cancer patients was Vrt -0.02cm, Log -0.02cm, Lat 0.01cm, Pit -0.01°, Rol -0.01°, Rtn -0.01°, SRS patients was Vrt 0.02cm, Log -0.05cm, Lat 0.00cm, Pit -0.30°, Rol -0.15°, Rtn -0.33°. there was no significant difference between the two regions. According to the IGRT standard of breast cancer patients, RMS was Vrt 0.26, Log 0.21, Lat 0.15, Pit 0.81, Rol 0.49, Rtn 0.59. Conclusion:. As a result of this study, the position error value of SGPS compared to LBPS did not show a significant difference between prostate cancer patients and SRS patients. In the case of additionally performed SGPS breast cancer patients, the position error value was not large based on IGRT. Therefore, it is considered that it will be useful to replace LBPS with SGPS, which has the great advantage of not requiring patient skin marking..

• The Journal of Korean Society for Radiation Therapy
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• v.32
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• pp.7-15
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• 2020

Purpose: In modern radiotherapy technology, several methods of image guided radiation therapy (IGRT) are used to deliver accurate doses to tumor target locations and normal organs, including CBCT (Cone Beam Computed Tomography) and other devices, ExacTrac System, other than CBCT equipped with linear accelerators. In previous studies comparing the two systems, positional errors were analysed rearwards using Offline-view or evaluated only with a Yaw rotation with the X, Y, and Z axes. In this study, when using CBCT and ExacTrac to perform 6 Degree of the Freedom(DoF) Online IGRT in a treatment center with two equipment, the difference between the set-up calibration values seen in each system, the time taken for patient set-up, and the radiation usefulness of the imaging device is evaluated. Materials and Methods: In order to evaluate the difference between mobile calibrations and exposure radiation dose, the glass dosimetry and Rando Phantom were used for 11 cancer patients with head circumference from March to October 2017 in order to assess the difference between mobile calibrations and the time taken from Set-up to shortly before IGRT. CBCT and ExacTrac System were used for IGRT of all patients. An average of 10 CBCT and ExacTrac images were obtained per patient during the total treatment period, and the difference in 6D Online Automation values between the two systems was calculated within the ROI setting. In this case, the area of interest designation in the image obtained from CBCT was fixed to the same anatomical structure as the image obtained through ExacTrac. The difference in positional values for the six axes (SI, AP, LR; Rotation group: Pitch, Roll, Rtn) between the two systems, the total time taken from patient set-up to just before IGRT, and exposure dose were measured and compared respectively with the RandoPhantom. Results: the set-up error in the phantom and patient was less than 1mm in the translation group and less than 1.5° in the rotation group, and the RMS values of all axes except the Rtn value were less than 1mm and 1°. The time taken to correct the set-up error in each system was an average of 256±47.6sec for IGRT using CBCT and 84±3.5sec for ExacTrac, respectively. Radiation exposure dose by IGRT per treatment was measured at 37 times higher than ExacTrac in CBCT and ExacTrac at 2.468mGy and 0.066mGy at Oral Mucosa among the 7 measurement locations in the head and neck area. Conclusion: Through 6D online automatic positioning between the CBCT and ExacTrac systems, the set-up error was found to be less than 1mm, 1.02°, including the patient's movement (random error), as well as the systematic error of the two systems. This error range is considered to be reasonable when considering that the PTV Margin is 3mm during the head and neck IMRT treatment in the present study. However, considering the changes in target and risk organs due to changes in patient weight during the treatment period, it is considered to be appropriately used in combination with CBCT.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.201-208
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• 2018

Purpose : The purpose of this study is to compare and analyze the set-up errors using the Combine IGRT with ExacTrac and CBCT phased in the treatment of Stereotatic Body Radiotherapy. Methods and materials : Patient who were treated Stereotatic Body Radiotherapy in the ulsan university hospital from May 2014 to november 2017 were classified as treatment area three brain, nine spine, three pelvis. First using ExacTrac Set-up error calibrated direction of Lateral(Lat), Longitudinal(Lng), Vertical(Vrt), Roll, Pitch, Yaw, after applied ExacTrac moving data in addition to use CBCT and set-up error calibrated direction of Lat, Lng, Vrt, Rotation(Rtn). Results : When using ExacTrac, the error in the brain region is Lat $0.18{\pm}0.25cm$, Lng $0.23{\pm}0.04cm$, Vrt $0.30{\pm}0.36cm$, Roll $0.36{\pm}0.21^{\circ}$, Pitch $1.72{\pm}0.62^{\circ}$, Yaw $1.80{\pm}1.21^{\circ}$, spine Lat $0.21{\pm}0.24cm$, Lng $0.27{\pm}0.36cm$, Vrt $0.26{\pm}0.42cm$, Roll $1.01{\pm}1.17^{\circ}$, Pitch $0.66{\pm}0.45^{\circ}$, Yaw $0.71{\pm}0.58^{\circ}$, pelvis Lat $0.20{\pm}0.16cm$, Lng $0.24{\pm}0.29cm$, Vrt $0.28{\pm}0.29cm$, Roll $0.83{\pm}0.21^{\circ}$, Pitch $0.57{\pm}0.45^{\circ}$, Yaw $0.52{\pm}0.27^{\circ}$ When CBCT is performed after the couch movement, the error in brain region is Lat $0.06{\pm}0.05cm$, Lng $0.07{\pm}0.06cm$, Vrt $0.00{\pm}0.00cm$, Rtn $0.0{\pm}0.0^{\circ}$, spine Lat $0.06{\pm}0.04cm$, Lng $0.16{\pm}0.30cm$, Vrt $0.08{\pm}0.08cm$, Rtn $0.00{\pm}0.00^{\circ}$, pelvis Lat $0.06{\pm}0.07cm$, Lng $0.04{\pm}0.05cm$, Vrt $0.06{\pm}0.04cm$, Rtn $0.0{\pm}0.0^{\circ}$. Conclusion : Combine IGRT with ExacTrac in addition to CBCT during Stereotatic Body Radiotherapy showed that it was possible to reduce the set-up error of patients compared to single ExacTrac. However, the application of Combine IGRT increases patient set-up verification time and absorption dose in the body for image acquisition. Therefore, depending on the patient's situation that using Combine IGRT to reduce the patient's set-up error can increase the radiation treatment effectiveness.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.577-584
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• 2013

IGRT(Image Guided Radiation Therapy) in radiation therapy is a very useful technique in order to increase setup of patient and position reproducibility. Tomotherapy can increase accuracy of setup to take IGRT by MVCT, but it be for verified accuracy of Image guided, and MVCT occurs the exposure of patient. Through this study, IGRT accuracy of Tomotherapy is very accurate within 1.0mm. When MVCT using Tomotherapy phantom for QA, QC be taken, exposure dose is Fine(2mm Slice thickness) 3cGy, Normal(4mm Slice thickness) 1.5cGy, Corse(6mmSlice thickness) 1.0cGy. Measurement value of spatial resolution using AAPM CT performance phantom did't cause a big difference. As a result, ability of IGRT in Tomotherapy is very accurate. While obtaining image for IGRT, we should minimize expose range because patient's be exposed to radiation. We should make an effort to do accurate radiation therapy to minimize exposure of patient by selecting the appropriate thickness of MVCT depending on patient's body and treat area.

• Radiation Oncology Journal
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• v.35 no.2
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• pp.180-184
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• 2017

Patients with locally advanced lung cancer and very limited pulmonary function (forced expiratory volume in 1 second $[FEV1]{\leq}1L$) have dismal prognosis and undergo palliative treatment or best supportive care. We describe two cases of locally advanced node-positive non-small cell lung cancer (NSCLC) patients with very limited lung function treated with induction chemotherapy and moderate hypofractionated image-guided radiotherapy (Hypo-IGRT). Hypo-IGRT was delivered to a total dose of 45 Gy to the primary tumor and involved lymph nodes. Planning was based on positron emission tomography-computed tomography (PET/CT) and four-dimensional computed tomography (4D-CT). Internal target volume (ITV) was defined as the overlap of gross tumor volume delineated on 10 phases of 4D-CT. ITV to planning target volume margin was 5 mm in all directions. Both patients showed good clinical and radiological response. No relevant toxicity was documented. Hypo-IGRT is feasible treatment option in locally advanced node-positive NSCLC patients with very limited lung function ($FEV1{\leq}1L$).

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.362-370
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• 2014

This study measured and analyzed the correlation coefficient between movements of thoracoabdominal tumors and external respiration in a free-breathing state, using cyberknife image guided radiotherapy(IGRT). This study subjects included a total of 30 patients with lung tumors(n=10), liver tumors(n=10) and pancreatic tumor(n=10) who underwent radiotherapy, and the movements of tumors were analyzed using converted log data of the tumor motion tracking system(MTS). In a free-breathing state, In relation to Peason's correlation coefficient between external respiration and lung tumors in the entire treatment process, the correlation coefficient was 0.646(p<0.05) in the cranio-caudal direction, 0.365(p<0.088) in the left and right direction and 0.196(p<0.115) in the antero-posterior direction. The correlation coefficient of liver tumors was 0.841(p<0.000) in the cranio-caudal direction, 0.346 (p<0.179) in the left and right direction and 0.691(p<0.001) in the antero-posterior direction. The correlation coefficient of Pancreatic tumors was 0.683(p<0.000) in the cranio-caudal direction, 0.397(p<0.006) in the left and right direction and 0.268(p<0.127) in the antero-posterior direction. In conclusion, the measurement findings of thoracoabdominal tumor movement using IGRT would be helpful in determining an accurate target volume. Moreover, the analysis of correlation between external respiration and movements of internal tumors would provide important information to correct movements of tumors for diverse radiotherapy techniques.