A method to get a size of the radiation isocenter of linear accelerators using star-shot images was presented and a computer program was developed to automate the method. Accuracy of the method was verified. The developed program was used to measure sizes of the radiation isocenters for a Clinac 21EX (Varian, USA) using data of quality assurance (QA) performed from June 2008 to December 2010. To calculated the size of radiation isocenter, positions of two points on each central ray of the star-shot image were found and the equation of the central ray was determined using the positions of two points. Using the equations of central rays the radius of the minimum circle intersecting all the central rays, which is one half of the size of radiation isocenter, was calculated. The program measured X-intercepts and y-intercepts of the central rays within errors of 0.084 mm and sizes of radiation isocenters within 0.053 mm. All the errors were less than the spatial resolution of star-shot images 0.085 mm. The radiation isocenter sizes of Clinac 21EX were 0.33+/-0.27 mm, 0.71+/-0.36 mm, 0.50+/-0.16 mm for collimator, gantry and couch respectively. During the measurement period all the measured sizes were less than 2.0 mm and within tolerance. The developed program could calculate the size of radiation isocenters and it would be helpful to routine QA.
Particle Accelerators ; Radius ; Software

Purpose: To evaluate the prognostic value of the pretreatment maximum standardized uptake value (SUVmax) for locoregional control (LRC) of early glottic cancer treated with primary radiotherapy. Materials and Methods: We retrospectively reviewed the medical records of 101 patients with T1-T2N0 glottic cancer treated with helical tomotherapy between 2013 and 2016. The clinical T-stages were T1 in 87 (86.1%) and T2 in 14 (13.9%) patients. The median total dose was 63 Gy (63–67.5 Gy) in 2.25 Gy per fraction. The survival outcomes were plotted using Kaplan-Meier curves. Receiver operating characteristic curves were used to assess the optimal SUVmax cut-off value for predicting locoregional recurrence. Results: The median follow-up period was 58 months (range, 11 to 90 months). The 5-year overall survival (OS) and locoregional recurrence-free survival rates were 96.8% and 85.4%, respectively. The median pretreatment SUVmax of the primary tumor for all 101 patients was 2.3 (range, 1.1 to 9.1). The best cut-off value for SUVmax for predicting LRC was 3.3, with a sensitivity of 78.6% and specificity of 73.6%. Univariate analysis showed that T-stage, overall treatment time (≥43 days), and high SUVmax (≥3.3) were significant predictors of LRC. Multivariate analysis showed that LRC was independently affected by a high SUVmax (≥3.3) (hazard ratio = 5.505, p = 0.020). Conclusion High pretreatment SUVmax (≥3.3) is a negative prognostic factor for LRC in early glottic cancer patients treated with primary radiotherapy.

Purpose: To assess risk factors of disease progression after salvage radiation therapy (SRT) with androgen deprivation therapy (ADT) in case of prostate-specific antigen (PSA) persistence after radical prostatectomy (RP). Materials and Methods: We analyzed 57 patients who received SRT with ADT between 2013 and 2019 due to PSA persistence after RP. The endpoint was disease progression defined by biochemical recurrence or clinical recurrence. Age, Pre-RP PSA level, Gleason score, pathologic stage, presence of pelvic lymph node dissection, surgical margins, and PSA at 6-8 weeks after RP were analyzed as predictive factors for disease progression. Kaplan-Meier method and Cox regression models were used for data analysis. Results: At a median follow-up of 38 months (interquartile range, 26–61), 17 patients had disease progression. Pathologic T stage (pT3b vs. pT3a or lower; hazard ratio [HR] = 9.20; p = 0.035) and PSA level at 6-8 weeks after RP (≥2.04 vs. <2.04 ng/mL; HR = 5.85; p = 0.002) were predictors of disease progression. The 5-year disease progression-free survival rate was 46.7% in pT3b group as compared to 92.9 % in pT3a or lower group, and 18.4% for PSA ≥2.04 ng/mL after RP as compared to 79.2% for PSA <2.04 ng/mL. Conclusion Pathological T stage (pT3b) and post RP PSA ≥2.04 ng/mL are independent risk factors of disease progression after SRT with ADT in patients with PSA persistence after RP.

Background and Objectives: 18F-fluorodeoxyglucose PET/CT scans can be a useful method to detect recurrence. However, its role in locally advanced head and neck squamous cell carcinomas (HNSCCs) patients after definitive chemoradiotherapy (CRT) has not yet been determined. The current study was performed to identify the role of therapeutic response evaluation using PET/CT after definitive CRT.Subjects and Method We conducted a retrospective review of patients with locally advanced HNSCCs, and who have undergone definitive CRT from 2009 to 2017 at a single institution. The patients were divided into two groups according to their responses to the treatment (metabolic complete remission [mCR] group or non-mCR group), assessed by PET/CT scans after definitive CRT. Results: Twenty-eight patients were consecutively enrolled. The most common primary site of cancer was the oropharynx, followed by the oral cavity, hypopharynx, and nasal cavity. The therapeutic response assessed by PET/CT scans was mCR in 14 patients. The median progression- free survival (PFS) was not reached in the mCR group but was 13.3 months for the non-mCR group (p=0.001). The median overall survival was significantly longer for the mCR group (52.5 months) than for the non-mCR group (15.2 months, p=0.002). A multivariate analysis showed PET/CT response and high-sensitivity C-reactive protein (hsCRP) as independent prognostic factors for PFS (mCR: p=0.027; hsCRP: p=0.042) and for the overall survival (mCR: p=0.006; hsCRP: p=0.020). Conclusion PET/CT scans after definitive CRT predicted the prognosis in patients with locally advanced HNSCCs. CRP was a prognostic factor affecting the outcomes of treatments.

Purpose: This study evaluates the radiation shielding performance of a new lead-free tungsten-based sheet to reduce the radiation exposure of operators and patients under C-arm fluoroscopy. Materials and Methods: A non-lead radiation shielding sheet (ROO201128; Pentas, Korea) was fabri-cated using tungsten and bismuth. The dose measurements were conducted using a C-arm fluoroscopy machine at 64 kVp and 1.5 mA, assuming two possible scenarios according to the position of the sheet. In each scenario, measurements were conducted at three distances (30, 60, and 90 cm) away from the beam center and in three directions (cephal, caudal, and operator’s direction). Results: In the area within a radius of 60 cm from the beam center, the measured doses were reduced by 66.3% on mean, and the doses measured at distances more than 60 cm were less than 0.1 mSv/h in both scenarios. The most beneficial utilization of the lead-free shielding sheet was verified during C-arm fluoroscopy by placing the sheet on the X-ray tube. The operator’s radiation exposure was reduced by 56.6% when the sheet was placed under the phantom, and by 81.0% when the sheet was placed on the X-ray tube. Conclusion The use of lead-free radiation shielding sheets under C-arm fluoroscopy was effective in reducing radiation exposure, and the most beneficial scenario in which the sheet can be utilized was verified when the sheet was placed on the X-ray tube.

Radiation therapy is an important treatment modality for abdominal or pelvic cancer, but there is a common and serious complication such as radiation-induced enteritis. Probiotics is reported to have positive effects against radiation-induced enteropathy. In this study, morphological changes of bowel mucosa were analyzed in rats to presume the effect of probiotics on radiation-induced enteritis and its correlation with radiation dose. A total of 48 adult male Sprague-Dawley rats were randomly assigned to two groups and received a solution containing 1.0x108 colony-forming units of Lactiobacillus acidophilus or water once daily for 10 days. Each of two groups was divided into three subgroups and abdomino-pelvic area of each subgroup was irradiated with 10, 15, and 20 Gy, respectively on the seventh day of feeding the solutions. All rats were sacrificed 3 days after irradiation and the mucosal thickness and villus height of jejunum, ileum and colon were measured. The morphological parameters of the small intestine represented significant differences between two solution groups irradiated 10 or 15 Gy, except for villus height of jejunum in 15 Gy-subgroup (P=0.065). There was no significant morphometric difference between two groups irradiated with 20 Gy of radiation. Probiotics appear to be effective for the morphological shortening of small intestinal mucosa damaged by radiation less than or equal to 15 Gy.
Animals ; Colon/pathology ; Disease Models, Animal ; Enteritis/pathology/prevention & control ; Ileum/pathology ; Intestinal Mucosa/microbiology/*radiation effects ; Intestine, Small ; Jejunum/pathology ; Lactobacillus acidophilus/*metabolism ; Male ; Probiotics/administration & dosage/*pharmacology ; Radiation Injuries, Experimental/*prevention & control/therapy ; Radiation Protection/*methods ; Random Allocation ; Rats ; Rats, Sprague-Dawley

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.
Brachytherapy ; Disease-Free Survival ; Drug Therapy ; Follow-Up Studies ; Humans ; Hysterectomy ; Medical Records ; Neoplasm Metastasis ; Pelvis ; Recurrence ; Retrospective Studies ; Survival Rate ; Uterine Cervical Neoplasms

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.

The kidney is one of the most radiosensitive organs in the abdominal cavity and is the dose-limiting structure in cancer patients receiving abdominal or total body irradiation. In the present study, the effect of coenzyme Q10 (CoQ10) on radiation nephropathy was evaluated in rats. A total of 72 rats were equally randomized into 4 groups: Control, CoQ10, irradiation with 10 Gy (RT) + placebo, or RT + CoQ10. The 2 RT groups received single 10 Gy of abdominal irradiation. The 2 CoQ10 groups were supplemented daily with 1 mL of soybean oil containing 10 mg/kg of CoQ10. The RT + placebo and control groups received same dose of soybean oil. After 24 weeks, laboratory and histopathologic findings were compared. The 2 RT groups showed significant increases in blood urea nitrogen (BUN) and creatinine levels and significant pathologic changes such as glomerulosclerosis and tubulointerstitial fibrosis. CoQ10 supplementation resulted in significant reductions of BUN and creatinine levels compared with the RT + placebo group (P < 0.001 and P = 0.038, respectively). CoQ10 treatment significantly attenuated glomerular and tubular changes of irradiated kidney in semiquantitative analysis (P < 0.001 for both). Administration of CoQ10 can alleviate the radiation-induced nephropathy.
Abdominal Cavity ; Animals ; Blood Urea Nitrogen ; Creatinine ; Fibrosis ; Humans ; Kidney ; Rats* ; Soybean Oil ; Whole-Body Irradiation