Purpose: This study compares the dosimetric properties of EBT3 and EBT4 GAFchromic films in transmission and reflection scanning modes, focusing on dose response, sensitivity, and postirradiation stability. Methods: The EBT3 and EBT4 films were irradiated at doses of 0–10 Gy using a Varian TrueBeam linear accelerator at 6 MV. The films were scanned at intervals between 1 and 336 hours after irradiation in both transmission and reflection modes. Net optical density (NetOD) values from each scan were used to evaluate dose response and sensitivity, with calibration curves created for each film and scan mode. Dose differences between calculated and delivered doses were assessed over time. Results: The EBT3 and EBT4 films exhibited similar dose–response curves and stable NetOD values across both scanning modes. However, EBT4 exhibited reduced sensitivity variability in response to dose changes. After irradiation, NetOD values increased up to 24 hours before stabilizing, suggesting that a 24-hour scan time is sufficient for consistent measurements. Dose differences between films and modes remained within ±4%. Conclusions EBT4 offers comparable dosimetric performance to EBT3, with additional benefits, such as improved dose–response linearity and reduced sensitivity fluctuations. The findings indicate that EBT4 can serve as a reliable successor to EBT3.

Purpose: This study compares the dosimetric properties of EBT3 and EBT4 GAFchromic films in transmission and reflection scanning modes, focusing on dose response, sensitivity, and postirradiation stability. Methods: The EBT3 and EBT4 films were irradiated at doses of 0–10 Gy using a Varian TrueBeam linear accelerator at 6 MV. The films were scanned at intervals between 1 and 336 hours after irradiation in both transmission and reflection modes. Net optical density (NetOD) values from each scan were used to evaluate dose response and sensitivity, with calibration curves created for each film and scan mode. Dose differences between calculated and delivered doses were assessed over time. Results: The EBT3 and EBT4 films exhibited similar dose–response curves and stable NetOD values across both scanning modes. However, EBT4 exhibited reduced sensitivity variability in response to dose changes. After irradiation, NetOD values increased up to 24 hours before stabilizing, suggesting that a 24-hour scan time is sufficient for consistent measurements. Dose differences between films and modes remained within ±4%. Conclusions EBT4 offers comparable dosimetric performance to EBT3, with additional benefits, such as improved dose–response linearity and reduced sensitivity fluctuations. The findings indicate that EBT4 can serve as a reliable successor to EBT3.

Purpose: This study compares the dosimetric properties of EBT3 and EBT4 GAFchromic films in transmission and reflection scanning modes, focusing on dose response, sensitivity, and postirradiation stability. Methods: The EBT3 and EBT4 films were irradiated at doses of 0–10 Gy using a Varian TrueBeam linear accelerator at 6 MV. The films were scanned at intervals between 1 and 336 hours after irradiation in both transmission and reflection modes. Net optical density (NetOD) values from each scan were used to evaluate dose response and sensitivity, with calibration curves created for each film and scan mode. Dose differences between calculated and delivered doses were assessed over time. Results: The EBT3 and EBT4 films exhibited similar dose–response curves and stable NetOD values across both scanning modes. However, EBT4 exhibited reduced sensitivity variability in response to dose changes. After irradiation, NetOD values increased up to 24 hours before stabilizing, suggesting that a 24-hour scan time is sufficient for consistent measurements. Dose differences between films and modes remained within ±4%. Conclusions EBT4 offers comparable dosimetric performance to EBT3, with additional benefits, such as improved dose–response linearity and reduced sensitivity fluctuations. The findings indicate that EBT4 can serve as a reliable successor to EBT3.

Purpose: This study compares the dosimetric properties of EBT3 and EBT4 GAFchromic films in transmission and reflection scanning modes, focusing on dose response, sensitivity, and postirradiation stability. Methods: The EBT3 and EBT4 films were irradiated at doses of 0–10 Gy using a Varian TrueBeam linear accelerator at 6 MV. The films were scanned at intervals between 1 and 336 hours after irradiation in both transmission and reflection modes. Net optical density (NetOD) values from each scan were used to evaluate dose response and sensitivity, with calibration curves created for each film and scan mode. Dose differences between calculated and delivered doses were assessed over time. Results: The EBT3 and EBT4 films exhibited similar dose–response curves and stable NetOD values across both scanning modes. However, EBT4 exhibited reduced sensitivity variability in response to dose changes. After irradiation, NetOD values increased up to 24 hours before stabilizing, suggesting that a 24-hour scan time is sufficient for consistent measurements. Dose differences between films and modes remained within ±4%. Conclusions EBT4 offers comparable dosimetric performance to EBT3, with additional benefits, such as improved dose–response linearity and reduced sensitivity fluctuations. The findings indicate that EBT4 can serve as a reliable successor to EBT3.

Purpose: This study compares the dosimetric properties of EBT3 and EBT4 GAFchromic films in transmission and reflection scanning modes, focusing on dose response, sensitivity, and postirradiation stability. Methods: The EBT3 and EBT4 films were irradiated at doses of 0–10 Gy using a Varian TrueBeam linear accelerator at 6 MV. The films were scanned at intervals between 1 and 336 hours after irradiation in both transmission and reflection modes. Net optical density (NetOD) values from each scan were used to evaluate dose response and sensitivity, with calibration curves created for each film and scan mode. Dose differences between calculated and delivered doses were assessed over time. Results: The EBT3 and EBT4 films exhibited similar dose–response curves and stable NetOD values across both scanning modes. However, EBT4 exhibited reduced sensitivity variability in response to dose changes. After irradiation, NetOD values increased up to 24 hours before stabilizing, suggesting that a 24-hour scan time is sufficient for consistent measurements. Dose differences between films and modes remained within ±4%. Conclusions EBT4 offers comparable dosimetric performance to EBT3, with additional benefits, such as improved dose–response linearity and reduced sensitivity fluctuations. The findings indicate that EBT4 can serve as a reliable successor to EBT3.

PURPOSE: This study aimed to report the clinical outcomes following selective neck irradiation (SNI) with lower elective radiation therapy (RT) dose in treating nasopharyngeal cancer (NPC) patients. MATERIALS AND METHODS: A total of 347 NPC patients received definitive RT according to our SNI policy and were retrospectively analyzed. The clinical target volumes (CTVs) were subdivided into CTV at high risk (CTV-HR) and CTV at low risk (CTV-LR). The typical doses to gross tumor volume (GTV), CTV-HR, and CTV-LR were 68.4-70.0 Gy, 54.0-60.0 Gy, and 36.0 Gy. RESULTS: With the median follow-up of 68.1 months (range, 2.3 to 197.1 months), the 5-year rates of loco-regional control and progression-free survival in all the patients were 85.0% and 70.8%, respectively. Thirty patients developed regional failure and the regional control rates at 3 and 5 years were 92.6% and 91.4%, respectively. The sites of regional failure in relation to the target volume were exclusively inside GTV/CTV-HR in 20, inside and outside GTV/CTVHR in three, and exclusively outside GTV/CTV-HR in seven, which were 5.7%, 0.9%, and 2.0% of total patients, respectively. CONCLUSION: The clinical outcomes by the current SNI policy were feasible and comparable to those following classic elective nodal irradiation policy.
Disease-Free Survival ; Follow-Up Studies ; Humans ; Lymphatic Irradiation ; Nasopharyngeal Neoplasms ; Nasopharynx ; Neck ; Radiotherapy ; Retrospective Studies ; Tumor Burden

A retrospective study was conducted to determine the mortality, causes and risk factors for death among HIV-infected patients receiving antiretroviral therapy (ART) in Korea. The outcomes were determined by time periods, during the first year of ART and during 1-5 yr after ART initiation, respectively. Patients lost to follow-up were traced to ascertain survival status. Among 327 patients initiating ART during 1998-2006, 68 patients (20.8%) died during 5-yr follow-up periods. Mortality rate per 100 person-years was 8.69 (95% confidence interval, 5.68-12.73) during the first year of ART, which was higher than 4.13 (95% confidence interval, 2.98-5.59) during 1-5 yr after ART. Tuberculosis was the most common cause of death in both periods (30.8% within the first year of ART and 16.7% during 1-5 yr after ART). During the first year of ART, clinical category B and C at ART initiation, and underlying malignancy were significant risk factors for mortality. Between 1 and 5 yr after ART initiation, CD4 cell count < or = 50 cells/microL at ART initiation, hepatitis B virus co-infection, and visit constancy < or = 50% were significant risk factors for death. This suggests that different strategies to reduce mortality according to the time period after ART initiation are needed.
Anti-Retroviral Agents/*adverse effects/*therapeutic use ; Antiretroviral Therapy, Highly Active/adverse effects ; CD4 Lymphocyte Count ; Cause of Death ; Coinfection ; Female ; HIV Infections/*drug therapy/*mortality/virology ; Humans ; Male ; Middle Aged ; Republic of Korea ; Retrospective Studies ; Risk Factors ; Treatment Outcome

BACKGROUND/AIMS: Increasing incidences of hepatitis C virus (HCV) infection in human immunodeficiency virus (HIV)-infected men who have sex were reported in the United States and Europe. However, few studies regarding the epidemiology of HCV infection in HIV-infected patients in Asian countries have been reported. METHODS: To determine the prevalence and incidence of HCV infection in HIV-infected patients, a retrospective cohort study was conducted. All HIV-infected patients who visited a tertiary care hospital in Korea from 2000 to 2013 were identified. Patients with ≥ 1 HCV antibody (Ab) test were included and observed until December 2014. RESULTS: Among 996 HIV-infected patients, 790 patients (79%) had baseline HCV Ab tests and 41 (5.2%) were positive at baseline and four at follow-up. Experience of injecting drug use (IDU; adjusted odds ratio, 16.20; 95% confidence interval [CI], 1.56 to 167.89; p < 0.01) was significantly associated with prevalent HCV infection. Conversion to HCV Ab positivity was observed in four of 384 included patients, with an incidence rate of 2.22 (95% CI, 0.60 to 5.80)/1,000 person-years (PYs); 164.89 (95% CI, 34.00 to 481.88)/1,000 PYs in patients with IDU, and 1.40 (95% CI, 0.35 to 7.79)/1,000 PYs in men who have sex with men who denied IDU. There was no significant increase in incidence rate of HCV in HIV-infected patients from 2009 to 2014 (p = 0.119). Among 19 patients who were positive for HCV RNA, genotype 1b (73%) was the most common following 2a/2c (20%). CONCLUSIONS: IDU was an independent risk factor for prevalent HCV infection. Prevalence of HCV infection was low and incidence of HCV infection was not significantly increased in HIV-infected patients in South Korea.
Asian Continental Ancestry Group ; Cohort Studies ; Epidemiology ; Europe ; Follow-Up Studies ; Genotype ; Hepacivirus* ; Hepatitis C* ; Hepatitis* ; HIV Infections ; HIV* ; Humans* ; Incidence* ; Korea* ; Male ; Odds Ratio ; Prevalence ; Retrospective Studies ; Risk Factors* ; RNA ; Substance-Related Disorders ; Tertiary Healthcare ; United States

Poor retention in care (RIC) is associated with higher antiretroviral therapy (ART) failure and worse survival. Identifying high risk patients for poor RIC is important for targeted intervention. A retrospective cohort study was conducted at a tertiary care hospital in Korea. HIV-infected patients initiating ART during 2002-2008 were included. 5 year-RIC was measured by hospital visit constancy (HVC) at 5 years after initiating ART. Among 247 enrolled patients, 179 (72.5%) remained in care, 20 (8.1%) were transferred to other hospitals, 9 (3.6%) died and 39 (15.8%) were lost to follow-up. We compared the demographic, psychosocial, and clinical characteristics between the groups with 100% HVC (n = 166, 67.2%) and < or = 50% HVC (n = 33, 13.4%). In multivariable analysis, ART-starting age < or = 30 years (odds ratio [OR] 4.08 vs. > 50; 95% confidence interval [CI] 1.10-15.15, P = 0.036), no non-HIV related comorbidity (OR 2.94 vs. comorbidity > or = 1; 95% CI 1.02-8.49, P = 0.046), baseline CD4 cell count > 300 cells/muL (OR 3.58 vs. < or = 200; 95% CI 1.33-9.65, P = 0.012) were significant predictable factors of poor RIC. HIV/AIDS care-givers should pay attention to young patients with higher baseline CD4 cell counts and no non-HIV related comorbidity.
Adult ; Anti-HIV Agents/*therapeutic use ; CD4 Lymphocyte Count ; CD4-Positive T-Lymphocytes/cytology ; Cohort Studies ; Comorbidity ; Demography ; Female ; HIV Infections/*drug therapy/mortality/psychology ; Hospitals ; Humans ; Male ; *Medication Adherence/psychology ; Middle Aged ; Multivariate Analysis ; Odds Ratio ; Republic of Korea ; Retrospective Studies

The epidemiology on human papillomavirus (HPV) among human immunodeficiency virus (HIV)-infected women in Korea is not well established. A retrospective study was conducted to determine the prevalence and genotype distribution of HPV infection among HIV-infected women in Korea. HPV DNA genotype and cervical cytology were examined in 60 HIV-positive women and 1,938 HIV-negative women. HPV genotypes were analyzed by using a HPV DNA chip. HIV-infected women had higher prevalence of high-risk HPV (hr-HPV) infection (30% vs 4.9%, adjusted odds ratio [AOR], 6.96; 95% confidence interval [CI], 3.63-13.34, P<0.001) and abnormal cervical cytology (18.3% vs 1.8%, AOR, 10.94; 95% CI, 5.18-23.1, P<0.001) compared with controls. The most common hr-HPV genotype detected in HIV-infected women was HPV 16 (10%), followed by 18 (6.7%) and 52 (5%). Prevalence of quadrivalent vaccine-preventable types (HPV 6, 11, 16, and 18) was 21.7% and 2.3% in HIV-positive women and HIV-negative women, respectively. Age was a significant risk factor for hr-HPV infection in HIV-infected women (P=0.039). The presence of hr-HPV was significantly associated with abnormal cervical cytology (P<0.001). These findings suggest that HPV testing for cervical cancer screening in HIV-infected women would be necessary, particularly among young age group.
Adult ; Age Factors ; Cervix Uteri/virology ; DNA Probes, HPV/diagnostic use ; DNA, Viral/genetics ; Female ; Genotype ; HIV Infections/complications/*epidemiology/genetics ; HIV-1/genetics ; Human papillomavirus 11/genetics/isolation & purification ; Human papillomavirus 16/genetics/isolation & purification ; Human papillomavirus 18/genetics/isolation & purification ; Human papillomavirus 6/genetics/isolation & purification ; Humans ; Middle Aged ; Papillomavirus Infections/complications/*epidemiology/*genetics ; Prevalence ; Republic of Korea/epidemiology ; Retrospective Studies ; Risk Factors ; Uterine Cervical Neoplasms/epidemiology/genetics/virology