Adjuvant external beam radiation and brachytherapy for vaginal resection margin positive cervical cancer

Donghyun Kim,Yongkan Ki,Wontaek Kim,Dahl Park,Joohye Lee,Jayoung Lee,Hosang Jeon,Jiho Nam 대한방사선종양학회 2018 Radiation Oncology Journal Vol.36 No.2

Purpose: To evaluate the treatment outcomes of adjuvant external beam radiation therapy (EBRT) and vaginal brachytherapy (VB) following radical hysterectomy in cervical cancer patients with involved vaginal resection margin (VRM). Materials and Methods: We retrospectively reviewed the medical records of 21 patients treated with postoperative EBRT and VB for positive VRM FIGO stage IB–IIA cervical cancer between 2003 and 2015. Concurrent platinum-based chemotherapy was administered to all patients. Results: The median whole pelvis EBRT dose was 50.4 Gy (range, 45 to 50.4 Gy). In the VB, the median dose per fraction, number of fractions, and total dose delivered were: 4 Gy (range, 3.0 to 4.0 Gy), 4 fractions (range, 3 to 5 fractions), and 16 Gy (range, 12 to 20 Gy), respectively. At a median follow-up of 46 months (range, 9 to 122 months), local recurrence was observed in 2 patients, and distant metastasis was present in 7 patients. All patients with local recurrence subsequently developed distant metastases. The 5-year local control, disease-free survival, and overall survival rates were 89.1%, 65.9%, and 62.9%, respectively. Of the 21 patients, 7 patients (33.3%) reported grade 2 acute toxicity; however, there were no grade 3 or higher acute adverse events. Grade 1–2 late toxicities were observed in 8 patients. Late grade 3 urinary toxicity was reported in 1 patient. Conclusions: Adjuvant EBRT and VB showed excellent local control and low toxicity in cervical cancer patients with positive VRM. Although limited by its retrospective nature, the findings from our study provide evidence supporting the use of additional VB in pathologically involved VRM.

Adjuvant external beam radiation and brachytherapy for vaginal resection margin positive cervical cancer

Kim, Donghyun,Ki, Yongkan,Kim, Wontaek,Park, Dahl,Lee, Joohye,Lee, Jayoung,Jeon, Hosang,Nam, Jiho The Korean Society for Radiation Oncology 2018 Radiation Oncology Journal Vol.36 No.2

Purpose: To evaluate the treatment outcomes of adjuvant external beam radiation therapy (EBRT) and vaginal brachytherapy (VB) following radical hysterectomy in cervical cancer patients with involved vaginal resection margin (VRM). Materials and Methods: We retrospectively reviewed the medical records of 21 patients treated with postoperative EBRT and VB for positive VRM FIGO stage IB-IIA cervical cancer between 2003 and 2015. Concurrent platinum-based chemotherapy was administered to all patients. Results: The median whole pelvis EBRT dose was 50.4 Gy (range, 45 to 50.4 Gy). In the VB, the median dose per fraction, number of fractions, and total dose delivered were: 4 Gy (range, 3.0 to 4.0 Gy), 4 fractions (range, 3 to 5 fractions), and 16 Gy (range, 12 to 20 Gy), respectively. At a median follow-up of 46 months (range, 9 to 122 months), local recurrence was observed in 2 patients, and distant metastasis was present in 7 patients. All patients with local recurrence subsequently developed distant metastases. The 5-year local control, disease-free survival, and overall survival rates were 89.1%, 65.9%, and 62.9%, respectively. Of the 21 patients, 7 patients (33.3%) reported grade 2 acute toxicity; however, there were no grade 3 or higher acute adverse events. Grade 1-2 late toxicities were observed in 8 patients. Late grade 3 urinary toxicity was reported in 1 patient. Conclusions: Adjuvant EBRT and VB showed excellent local control and low toxicity in cervical cancer patients with positive VRM. Although limited by its retrospective nature, the findings from our study provide evidence supporting the use of additional VB in pathologically involved VRM.

Utility of split-VMAT for cardiac protection during left breast cancer radiotherapy

Kim Dong Woon,Jeon Hosang,Ki Yongkan,Joo Ji Hyeon,Kim Wontaek,Kim Donghyeon,Park Dahl,Nam Jiho 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.5

The feld-in-feld technique of three-dimensional conformal radiotherapy (3D-CRT) is a common treatment technique used in breast radiation therapy. However, when the heart is largely included in the treatment feld for the treatment of left breast cancer, it is unavoidable that a large dose will impact the heart. Increases in the mean dose and the maximum dose to the heart increase the hazard ratio for ischemic heart disease. Split-VMAT is a technique that combines tangential feld and volumetric modulated arc therapy (VMAT) methods using multiple small partial arcs. Split-VMAT can reduce the maximum dose to the heart and while ensuring target coverage. In this study, we sought to confrm the utility of split-VMAT for patients with left breast cancer whose heart is more than 1 cm inside the treatment feld. The split-VMAT plan consisted of 4 felds, set at 20–60° per feld, and the treatment time was limited to less than 20 s to enable deep-inspiration breath hold (DIBH). A half-VMAT, consisting of an arc of 180° and a feld-in-feld approach, using 2 tangential felds symmetrical to each other, were used as comparison groups. In addition, the feld-in-feld technique was divided into 2 types, 1 that emphasized target coverage and the other that focused on heart protection. For treatment, an Elekta Versa HD linear accelerator was used, and treatment planning was performed using Elekta Monaco software. Both split-VMAT and feld-in-feld, focused on target coverage achieved better (>3%) target coverage. However, in feld-in-feld, focused on target coverage, the maximum dose to the heart was very high. Compared to the both feld-in-feld-based technique, the average dose to the lungs was about twice as high in the both VMAT-based technique. In addition, the treatment time per feld was increased by about 5 s, and the total treatment time was more than doubled. The 3D-CRT feld-in-feld technique can signifcantly protect organs at risk (OARs) not included in the radiation feld because the gantry is not directed to inside the body. However, if the heart is, the OAR, it may be exposed to high radiation doses. The split-VMAT limits the angle of the arc, constraining the beam directed inside the patient's body, and shortens the treatment time to allow DIBH. In addition, since sufcient target coverage and heart protection are possible, split-VMAT can be a compromise between 3D-CRT, intensity-modulation radiotherapy, and conventional VMAT.

Adaptive Image Rescaling for Weakly Contrast-Enhanced Lesions in Dedicated Breast CT: A Phantom Study

Kim Bitbyeol,Kim Ho Kyung,Kim Jinsung,Ki Yongkan,Joo Ji Hyeon,전호상,Park Dahl,Kim Wontaek,Nam Jiho,Kim Dong Hyeon 대한영상의학회 2021 대한영상의학회지 Vol.82 No.6

Purpose Dedicated breast CT is an emerging volumetric X-ray imaging modality for diagnosis that does not require any painful breast compression. To improve the detection rate of weakly enhanced lesions, an adaptive image rescaling (AIR) technique was proposed. Materials and Methods Two disks containing five identical holes and five holes of different diameters were scanned using 60/100 kVp to obtain single-energy CT (SECT), dual-energy CT (DECT), and AIR images. A piece of pork was also scanned as a subclinical trial. The image quality was evaluated using image contrast and contrast-to-noise ratio (CNR). The difference of imaging performances was confirmed using student’s t test. Results Total mean image contrast of AIR (0.70) reached 74.5% of that of DECT (0.94) and was higher than that of SECT (0.22) by 318.2%. Total mean CNR of AIR (5.08) was 35.5% of that of SECT (14.30) and was higher than that of DECT (2.28) by 222.8%. A similar trend was observed in the subclinical study. Conclusion The results demonstrated superior image contrast of AIR over SECT, and its higher overall image quality compared to DECT with half the exposure. Therefore, AIR seems to have the potential to improve the detectability of lesions with dedicated breast CT.

Minimization of Treatment Time Using Partial-Arc Volumetric Modulated Arc Therapy with Bladder Filling Protocol for Prostate Cancer

Hojeong Lee,Dong Woon Kim,Ji Hyeon Joo,Yongkan Ki,Wontaek Kim,Dahl Park,Jiho Nam,Dong Hyeon Kim,Hosang Jeon Korean Society of Medical Physics 2022 의학물리 Vol.33 No.4

Purpose: Radiotherapy after bladder filling protocol (BFP) is known to enhance treatment quality and reduce side effects in prostate cancer, a common male solid cancer globally. However, due to the need to hold back urine during treatment, patients frequently complain of discomfort, and treatment is frequently suspended when patients urinate during treatment and urine penetrates the treatment device, causing malfunction. Therefore, the effect of minimizing treatment time when partial-arc volumetric modulated arc therapy (VMAT) was used instead of full-arc was assessed in this study. Methods: A total of 70 plans were created in 10 patients using 7 different arc sizes, and the treatment time for each plan was calculated. Results: Reduced arc size by half resulted in a 54.4% decrease in mean treatment duration, with a proportional tendency observed. Furthermore, the effect of VMAT arc size reduction on target dose homogeneity was significantly limited, and the effect on surrounding organs at risk (OAR) was negligible. It should be noted, however, that when the arc size decreases by >40%, the dose increases in the area without OAR around the target. Conclusions: The results of this study demonstrated that partial-arc VMAT for enhancing treatment convenience and efficacy of prostate cancer patients undergoing BFP can achieve a considerable reduction in treatment time while preserving treatment quality, and it is expected to be useful for partial-arc VMAT plan design and implementation in practice.

A deep-learning method using single phantom to enhance megavoltage image quality for patient positioning in chest radiotherapy: a feasibility study

Jeon Hosang,Kim Dong Woon,Joo Ji Hyeon,Ki Yongkan,Kim Wontaek,Park Dahl,Nam Jiho,Kim Dong Hyeon 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.1

Image-guided radiation treatment (IGRT) is essential for verifying patient positioning during modern radiotherapy. Although megavoltage digital radiographs (MV-DR) are available on most therapeutic linear accelerators and can be used for checking treatment beam shapes, they are much inferior to kilovoltage digital radiographs (KV-DR) in terms of image quality. As it is generally challenging to obtain a well-aligned MV−KV training dataset of patients in clinical scenarios, there is a lack of sufcient information on the accuracy of KV-DR synthesized using supervised training. Therefore, we aimed to synthesize pseudo KV-DR (pKV-DR) from MV-DR using a training dataset developed with a single anthropomorphic chest phantom. The phantom was adopted to obtain MV−KV image pairs at various gantry angles because these image pairs of patients are highly difcult to acquire and exactly align with each other. A deep-learning model based on U-net architecture was trained with the phantom image pairs using the mean absolute error (MAE) and structure similarity (SSIM) indices as loss functions. The mean MAEs of MV-DR and pKV-DR against KV-DR as the ground truth were 0.1152 and 0.0169, respectively, and their mean SSIM values were 0.9693 and 0.9942, respectively. Finally, pKV-DR showed a relatively high image similarity to that of KV-DR with smaller MAE (14.7%) and higher SSIM (2.5%), compared with MV-DR. The image contrast was also improved by 37.1% in clinical cases. The proposed method is expected to enable the implementation of improved IGRT with high image quality of KV-DR level, even in clinics where MV-DR is only available.

Structure of an Oncology Information System Based on a Cost-Effective Relational Database for Small Departments of Radiation Oncology

Jeon, Hosang,Kim, Dong Woon,Joo, Ji Hyeon,Ki, Yongkan,Kim, Wontaek,Park, Dahl,Nam, Jiho,Kim, Dong Hyeon Korean Society of Medical Physics 2020 의학물리 Vol.31 No.4

Purpose: Radiation oncology information systems (ROIS) have evolved toward connecting and integrating information between radiation treatment procedures. ROIS can play an important role in utilizing modern radiotherapy techniques that have high complexity and require a large amount of information. Methods: Using Access^TM software, we have developed a relational database that is highly optimized for a radiotherapeutic workflow. Results: The prescription table was chosen as the core table to which the other tables were connected, and three types of forms-charts, worklists, and calendars- were suggested. A fast and reliable channel for delivering orders and remarks according to changes in the situation was also designed. Conclusions: We expect our ROIS design to inspire those who need to develop and manage an individual ROIS suitable for their radiation oncology departments at a low cost.

Feasibility of Improving the Accuracy of Dose Calculation Using Hybrid Computed Tomography Images: A Phantom Study

Jeon, Hosang,Kim, Dong Woon,Joo, Ji Hyeon,Ki, Yongkan,Kim, Wontaek,Park, Dahl,Nam, Jiho,Kim, Dong Hyeon Korean Society of Medical Physics 2021 의학물리 Vol.32 No.1

Purpose: Kilovoltage computed tomography (kV-CT) is essential for radiation treatment planning. However, kV-CT images are significantly distorted by artifacts when a metallic prosthesis is present in the patient's body. Thus, the accuracies of target delineation and treatment dose calculation are inevitably lowered. We evaluated the accuracy of the calculated doses using an image restoration method with hybrid CT, which was introduced in our previous study. Methods: A cylindrical phantom containing four metals, namely, silver, copper, tin, and tungsten, was scanned using kV-CT and megavoltage CT to produce hybrid CT images. We created six verification plans for three head and neck patients on kV-CT and hybrid CT images of the phantom and calculated their doses. The actual doses were measured with film patches during beam delivery using tomotherapy. We used the gamma evaluation method to compare dose distribution between kV-CT and hybrid CT with three gamma criteria, namely, 3%/3 mm, 2%/2 mm, and 1%/1 mm. Results: The gamma pass rates decreased as the gamma criteria were strengthened, and the pass rate of hybrid CT was higher than that of kV-CT in all cases. When the 1%/1 mm criterion was used, the difference in gamma pass rates between them was up to 13%p. Conclusions: According to our findings, we expect that the use of hybrid CT can be a suitable approach to avoid the effect of severe metal artifacts on the accuracy of dose calculation and contouring.

Generation of hybrid sinograms for the recovery of kV-CT images with metal artifacts for helical tomotherapy

Jeon, Hosang,Park, Dahl,Youn, Hanbean,Nam, Jiho,Lee, Jayoung,Kim, Wontaek,Ki, Yongkan,Kim, Yong Ho,Lee, Ju Hye,Kim, Dongwon Published for the American Association of Physicis 2015 Medical physics Vol.42 No.8

Experimental Study of In-vivo Dosimetry Using Glass Rod Dosimeters to Minimize the Initialization

Jeon, Hosang,Nam, Jiho,Lee, Jayoung,Lee, Juhye,Park, Dahl,Kim, Wontaek,Ki, Yongkan,Kim, Donghyun 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.5

<P>In-vivo dosimetry, in which small detector elements are attached to a patient's body, is an important technique for directly evaluating radiation treatment doses. The glass rod dosimeter (GRD) possesses several advantages over alternatives, which makes it one of the most useful detectors for in-vivo dosimetry. However, because the GRD initialization process requires a prolonged exposure at very high temperatures, as well as subsequent gradual quenching, each measurement takes approximately a day to complete. Therefore, we investigated the reliability of a GRD used repeatedly without initialization processes to improve efficiency. Ten doses of 0.5 Gy were delivered and read using three GRD elements. Then, the same procedure was performed for doses of 1.0 Gy. A readout error of less than 2% was maintained for up to three irradiation doses. However, the fluctuations in the readout data increased significantly as the number of irradiation doses increased. In addition, we discovered that the combined uncertainty of the readouts was influenced more heavily by the cumulative amount of irradiation than it was by the number of doses. Our results should provide guidance for accurate and efficient GRD use.</P>