• Radiation Oncology Journal
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• v.36 no.2
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• pp.85-94
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• 2018

Radiation-induced second malignancies (RISM) is one of the important late side effects of radiation therapy and has an impact on optimal treatment decision-making. Many factors contribute to the development of RISM such as age at radiation, dose and volume of irradiated area, type of irradiated organ and tissue, radiation technique and individual and family history of cancer. Exact mechanism of RISM is unknown. But nowadays, it is a growing concern in oncology because of the increased number of cancer survivors and efforts are being made to prevent or decrease the incidence of RISM. The primary search for articles was carried via Google Scholar and PubMed with keywords included 'radiation induced malignancies, second malignancies, and chemotherapy induced malignancies'. Additional papers were found through references from relevant articles. In this review article, we have discussed about the pathogenesis, factors contributing to RISM, screening and prevention strategies of RISM.

• Journal of Chest Surgery
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• v.54 no.5
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• pp.433-435
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• 2021

Pleural adhesions are a major challenge in standard and nonintubated video-assisted thoracic surgery. The currently available imaging techniques help to assess the presence and extent of pleural adhesions, but do not provide information on tissue deformability, which is crucial for intraoperative management. In this report, we describe the utilization of real-time elastography mapping of pleural adhesions. This technique enabled us to detect areas with softer adhesions, and helped establish the surgical plan in a difficult case of a patient scheduled for nonintubated video-assisted thoracic surgery.

• Yonsei Medical Journal
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• v.59 no.9
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• pp.1049-1056
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• 2018

Purpose: Local recurrence is the most common cause of failure in retroperitoneal soft tissue sarcoma patients after surgical resection. Postoperative radiotherapy (PORT) is infrequently used due to its high complication risk. We investigated the efficacy of PORT using modern techniques in patients with retroperitoneal soft tissue sarcoma. Materials and Methods: Eighty patients, who underwent surgical resection for non-metastatic primary retroperitoneal soft tissue sarcoma at the Yonsei Cancer Center between 1994 and 2015, were retrospectively reviewed. Thirty-eight (47.5%) patients received PORT: three-dimensional conformal radiotherapy in 29 and intensity-modulated radiotherapy in nine patients. Local failure-free survival (LFFS), overall survival (OS), and RT-related toxicities were investigated. Results: Median follow-up was 37.1 months (range, 5.8-207.9). Treatment failure occurred in 47 (58.8%) patients including local recurrence in 33 (41.3%), distant metastasis in eight (10%), and both occurred in six (7.5%) patients. The 2-year and 5-year LFFS rates were 63.9% and 47.9%, respectively. The 2-year and 5-year OS rates were 87.5% and 71.1%. The 5-year LFFS rate was significantly higher in PORT group than in no-PORT group (74.2% vs. 24.3%, p<0.001). In multivariate analysis, PORT was the only independent prognostic factor for LFFS. However, there was no significant correlation between RT dose and LFFS. OS showed no significant difference between the two groups. Grade ${\leq}2$ acute toxicities were observed in 63% of patients, but no acute toxicity ${\geq}$ grade 3 was observed. Conclusion: PORT using modern technique markedly reduced local recurrence in retroperitoneal sarcoma patients, with low toxicity. The optimal RT technique, in terms of RT dose and target volume, should be further investigated.

• Radiation Oncology Journal
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• v.32 no.4
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• pp.247-255
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• 2014

Purpose: To determine whether neoadjuvant androgen deprivation therapy (NADT) improves clinical outcomes in patients with prostate cancer treated with definitive radiotherapy. Materials and Methods: We retrospectively reviewed medical records of 201 patients with prostate cancer treated with radiotherapy between January 1991 and December 2008. Of these, 156 patients with more than 3 years of follow-up were the subjects of this study. The median duration of follow-up was 91.2 months. NADT was given in 103 patients (66%) with median duration of 3.3 months (range, 1.0 to 7.7 months). Radiation dose was escalated gradually from 64 Gy to 81 Gy using intensity-modulated radiotherapy technique. Results: Biochemical relapse-free survival (BCRFS) and overall survival (OS) of all patients were 72.6% and 90.7% at 5 years, respectively. BCRFS and OS of NADT group were 79.5% and 89.8% at 5 years and those of radiotherapy alone group were 58.8% and 92.3% at 5 years, respectively. Risk group (p = 0.010) and radiation dose ${\geq}70Gy$ (p = 0.017) affected BCRFS independently. NADT was a significant prognostic factor in univariate analysis, but not in multivariate analysis (p = 0.073). Radiation dose ${\geq}70Gy$ was only an independent factor for OS (p = 0.007; hazard ratio, 0.261; 95% confidence interval, 0.071-0.963). Conclusion: NADT prior to definitive radiotherapy did not result in significant benefit in terms of BCRFS and OS. NADT should not be performed routinely in the era of dose-escalated radiotherapy.

• Progress in Medical Physics
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• v.34 no.4
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• pp.41-47
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• 2023

Purpose: This study aimed to dosimetrically compare the technique of three-dimensional conformal radiotherapy (3D CRT), which is a traditional prophylactic cranial irradiation method, and the intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques used in the last few decades with the dynamic conformal arc therapy (DCAT) technique. Methods: The 3D CRT, VMAT, IMRT, and DCAT plans were prepared with 25 Gy in 10 fractions in a Monaco planning system. The target volume and the critical organ doses were compared. A comparison of the body V₂, V₅, and V₁₀ doses, monitor unit (MU), and beam on-time values was also performed. Results: In planned target volume of the brain (PTV_Brain), the highest D99 dose value (P<0.001) and the most homogeneous (P=0.049) dose distribution according to the heterogeneity index were obtained using the VMAT technique. In contrast, the lowest values were obtained using the 3D CRT technique in the body V₂, V₅, and V₁₀ doses. The MU values were the lowest when DCAT (P=0.001) was used. These values were 0.34% (P=0.256) lower with the 3D CRT technique, 66% (P=0.001) lower with IMRT, and 72% (P=0.001) lower with VMAT. The beam on-time values were the lowest with the 3D CRT planning (P<0.001), 3.8% (P=0.008) lower than DCAT, 65% (P=0.001) lower than VMAT planning, and 76% (P=0.001) lower than IMRT planning. Conclusions: Without sacrificing the homogeneous dose distribution and the critical organ doses in IMRTs, three to four times less treatment time, less low-dose volume, less leakage radiation, and less radiation scattering could be achieved when the DCAT technique is used similar to conventional methods. In short, DCAT, which is applicable in small target volumes, can also be successfully planned in large target volumes, such as the whole-brain.

• Radiation Oncology Journal
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• v.26 no.4
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• pp.222-228
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• 2008

Purpose: Various treatment techniques have been attempted for the radiotherapy of anal cancer because of acute side effects such as perineal skin reactions. This study was performed to investigate an optimal radiotherapy technique in anal cancer. Materials and Methods: The study subjects included 35 patients who underwent definitive concurrent chemoradiotherapy for anal cancer in Yonsei Cancer Center between 1990 and 2007. The patients' clinical data, including irradiation technique, were reviewed retrospectively. The primary lesion, regional lymph nodes, and both inguinal lymph nodes were irradiated by $41.4{\sim}45\;Gy$ with a conventional schedule, followed by a boost does to the primary lesion or metastatic lymph nodes. The radiotherapy technique was classified into four categories according to the irradiation field and number of portals. In turn, acute skin reactions associated with the treatment interruption period were investigated according to each of the four techniques. Results: 28 patients (80.0%) had grade 2 radiation dermatitis or greater, whereas 10 patients (28.6%) had grade 3 radiation dermatitis or greater during radiotherapy. Radiation dermatitis and the treatment interruption period were relatively lower in patients belonging to the posterior-right-left 3 x-ray field with inguinal electron boost and in patients belonging to electron thunderbird techniques. The interruption periods were $8.2{\pm}10.2$ and $5.7{\pm}7.7$ for the two technique groups, respectively. Twenty-seven patients (77.1%) went into complete remission at 1 month after radiotherapy and the overall 5 year survival rates were 67.7%. Conclusion: Field size and beam arrangement can affect patients' compliance in anal cancer radiotherapy, whereas a small x-ray field for the perineum seems to be helpful by decreasing severe radiation dermatitis.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3816-3823
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• 2022

This work analyzed the dosimetric difference between the intensity modulated radiotherapy (IMRT), partial/single/double-arc volumetric modulated arc therapy (PA/SA/DA-VMAT) techniques in treatment planning for treating more than one target of lung cancer at different isocenters. IMRT and VMAT plans at different isocenters were created systematically using a Harold heterogeneous lung phantom. The conformity index (CI), homogeneity index (HI), gradient index (GI), dose-volume histogram and mean and maximum dose of the PTV were calculated and analyzed. Furthermore, the dose-volume histogram and mean and maximum doses of the OARs such as right lung, contralateral lung and non GTV were determined from the plans. The IMRT plans showed the superior target dose coverage, higher mean and maximum values than other VMAT techniques. PA-VMAT technique shows more lung sparing and DA-VMAT increases the V_5/10/20 values of contralateral lung than other VMAT and IMRT techniques. The IMRT technique achieves highly conformal dose distribution to the target than other VMAT techniques. Comparing to the IMRT plans, the higher V_5/10/20 and mean lung dose were observed in the contralateral lung in the DA-VMAT.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.90-100
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• 2017

Purpose: To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers. Materials and Methods: We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients. Results: The conformity index average of all patients followed by standard deviation (${\bar{x}}{\pm}{\sigma}_{\bar{x}}$) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were $1.72{\pm}0.56$, $1.67{\pm}0.57$, $1.83{\pm}0.65$, and $1.85{\pm}0.64$, and homogeneity index were $0.059{\pm}0.05$, $0.064{\pm}0.05$, $0.064{\pm}0.04$, and $0.064{\pm}0.05$. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Conclusion: Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.

• Radiation Oncology Journal
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• v.37 no.1
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• pp.22-29
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• 2019

Purpose: The aim of this study is to evaluate the efficacy and feasibility of four-field box whole brain radiotherapy (FB-WBRT) with tilting baseplate by comparing bilateral WBRT (B-WBRT). Methods and Materials: Between March 2016 and September 2018, 20 patients with brain metastases underwent WBRT using the four-field box technique. WBRT is performed with a dose of 30 Gy in 10 fractions daily. Two computed tomography simulations per person were performed. One was in the traditional supine position for B-WBRT and the other by applying the tilting acrylic supine baseplate to elevate the head by 40° for FB-WBRT. The B-WBRT used the field-in-field technique, which is the most commonly used method in our institution. The FB-WBRT comprised anterior, posterior, and bilateral beams. A wedge was applied in anterior and posterior fields to compensate for skull convexity. Results: The average of Dmean of both parotid glands was 10.2 Gy (range, 3.8 to 17.8 Gy) in B-WBRT and 5.4 Gy (range, 2.0 to 11.7 Gy) in FB-WBRT (p < 0.05). Compared to B-WBRT, FB-WBRT reduced the mean dose of the right and left parotid glands from 10.1 Gy to 4.9 Gy and from 10.4 Gy to 5.8 Gy, respectively (p < 0.05). Further, V₅, V₁₀, V₁₅, V₂₀, and V₂₅ for the parotid gland decreased significantly in FB-WBRT (p < 0.05). The Dmax and Dmean of lens decreased according to the dose-volume histogram. Conclusion: Compared to B-WBRT, FB-WBRT with a tilting baseplate is a simple and effective method that takes feature of noncoplanar beam to protect the parotid gland.

• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.83-89
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• 1986

High energy radiation therapy using accelerator or radioioisotope teletherapy unit is now one of the most important modality in the field dealing with human malignant tumor. It's successful technology overcomes incurable disease to change into curable disease not only by the improvement of clinical technique but also by the development of radiation physics and biology. The author presented the principles of radiation therapy by means of basic knowledge of medicine. physics and biology, described the various ways to improve the result of radiation therapy, and reviewed recent status of radiotherapy field in Korea.