Radio Frequency Identification Gate System to Identify Misused Personal Dosimeters.

The use of two personal dosimeters, one worn over and one worn under a protective apron, provides the best estimate of effective dose. However, inappropriate positioning of dosimeters is a common occurrence, resulting in abnormally high or low radiation exposure records. Although such incorrect positioning can be identified by radiation exposure records, doing so is time-consuming and labor-intensive for administrators. Therefore, a system that can identify incorrect locations of dosimeters without burdening administrators must be developed. In this study, we developed a radio frequency identification (RFID) gate system that can differentiate between two RFID-tagged dosimeters placed over and under a metal apron and identify misused dosimeters. To simulate the position of the RFID-tagged dosimeters, we designed four dosimeter-wearing classes, including "proper use" and three types of "misuse" (i.e., "reversed," "both under," and "both over"). When the system predicts "misuse" based on the tag reading, the worker is alerted with lights and alarms. The system performance was evaluated using a confusion matrix, with an overall accuracy of 97.75%, demonstrating high classification performance. The safety of the system against life support devices was also investigated, demonstrating that they were not affected by the electric field at 0.3 m or more from the antenna of the system under any transmit powers tested. This RFID gate system is highly capable of identifying incorrectly positioned dosimeters, enabling real-time monitoring of dosimeters to manage their positioning.

Impact on liver position under breath-hold by computed tomography contrast agents in stereotactic body radiotherapy of liver cancer.

BACKGROUND: We investigated variations in liver position relative to the vertebral bone for liver cancer treated with stereotactic body radiation therapy under expiratory phase breath-hold (BH) for treatment with contrast-enhanced-computed tomography (CECT), non-CECT, and cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Seventeen consecutive patients using a contrast enhancement (CE) agent for the CT simulation session for this retrospective study were selected. The first computed tomography (CT) scan without the use of CE agent in the expiratory phase was used for treatment planning (pCT). The remaining three CT scans without a CE agent under expiratory phase BH were acquired successively without repositioning to evaluate the intra-fraction variation in liver position. Furthermore, a three-phase CT scan (arterial, portal, and late phases) accompanied by a CE agent under expiratory phase BH was acquired for target delineation. CBCT scans without the use of a CE agent under expiratory phase BH were acquired for treatment. Inter-fractional variations (non-CECT or CECT) in liver position were measured using the difference between CBCT and pCT or each 3 phase CECT images, respectively. RESULTS: The average ± standard deviations for intrafractional, non-CECT interfractional variations, and CECT interfractional variations were 1.0 ± 1.3, 2.5 ± 2.6, and 6.4 ± 6.4 mm, respectively, in the craniocaudal (CC) direction. Intra- and inter-fractional variations in liver position were relatively small for non-CECT. However, significant inter-fractional liver position variations in CECT were observed in the expiratory phase BH. The position of the liver should be carefully considered when applying CECT images for image-guided radiotherapy.

Stereotactic body radiotherapy for patients with small hepatocellular carcinoma ineligible for resection or ablation therapies.

AIM: To evaluate the efficacy and safety of stereotactic body radiotherapy (SBRT) in patients with small hepatocellular carcinoma (HCC) who were ineligible for resection or ablation therapies. METHODS: Overall, 65 patients with 74 HCC (median tumor size, 16 mm) were enrolled. They were treated at the prescribed dose of 48 Gy in four fractions at the isocenter. Child-Turcotte-Pugh (CTP) scoring was used to classify 56 and nine patients into classes A and B, respectively. Local progression was defined as irradiated tumor growth on a dynamic computed tomography follow up. The median follow-up period was 26 months. Tumor responses were assessed according to the modified Response Evaluation Criteria in Solid Tumors. Treatment-related toxicities were evaluated according to the Common Terminology Criteria for Adverse Events version 4.0. RESULTS: The 2-year overall survival, progression-free survival and local control rates were 76.0% (95% confidence interval [CI], 65.4-86.7%), 40.0% (95% CI, 27.6-52.3%) and 100% (95% CI, 100%), respectively. At 6-12 months after SBRT, grade 3 or higher toxicities was observed in 15 (23.1%) patients. The incidence of grade 3 or higher toxicities was higher in CTP class B than in class A (P = 0.0127). CONCLUSION: SBRT was effective and relatively safe for patients with small HCC who were ineligible for resection or ablation therapies.

Role of 3-D conformal radiotherapy for major portal vein tumor thrombosis combined with hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma.

AIM: To evaluate the response, survival and safety on 3-D conformal radiotherapy (3D-CRT) for major portal vein tumor thrombosis (PVTT) combined with hepatic arterial infusion chemotherapy (HAIC) for advanced hepatocellular carcinoma (HCC). METHODS: In this retrospective study, 83 advanced HCC patients treated with HAIC who met the following criteria were enrolled: (i) PVTT of the main trunk or first branch of the portal vein; (ii) no extrahepatic metastasis; (iii) Child-Pugh score of 5-7; (iv) performance status of 0 or 1; and (v) no history of sorafenib treatment. The response, overall survival (OS), time to treatment failure (TTF), post-progression survival (PPS) and safety were compared between HAIC combined with 3D-CRT for PVTT (RT group, n = 41) and HAIC alone (non-RT group, n = 42). RESULTS: The objective response of PVTT was significantly higher in the RT group (56.1%) than in the non-RT group (33.3%), while that of intrahepatic tumor and OS were not significantly different between groups. Median OS, TTF and PPS were significantly longer in the RT group than in the non-RT group (8.6 and 5.0 months, 5.0 and 2.7 months, and 5.3 and 1.5 months, respectively) among intrahepatic tumor non-responders to HAIC, whereas those were not significantly different between groups among intrahepatic tumor responders to HAIC. By multivariate analysis, the combination of 3D-CRT with HAIC was an independent contributing factor for OS (hazard ratio, 3.2; 95% confidence interval, 1.692-6.021; P < 0.001) among intrahepatic HCC non-responders to HAIC. CONCLUSION: 3D-CRT for PVTT combined with HAIC could provide survival benefit to non-responder to HAIC.

Long-term results of definitive concurrent chemoradiotherapy for patients with esophageal submucosal cancer (T1bN0M0).

BACKGROUND: The long-term outcomes of definitive concurrent chemoradiotherapy for patients with esophageal submucosal cancer without regional and distant metastasis were retrospectively analyzed. METHODS: Patients with histologically confirmed esophageal submucosal cancers without regional and distant metastasis who received definitive concurrent chemoradiotherapy from 2001 to 2011 were included. Radiation therapy of a median total dose of 60 Gy/30 fractions (range, 54-66 Gy) with elective nodal irradiation of 40 Gy was combined concurrently with 5-furuorouracil-based chemotherapy. RESULTS: Thirty-six patients (33 men and 3 women) aged from 45 to 80 years (median, 67 years) were assessed. All patients had squamous cell carcinoma. With a median follow-up time of 61 months, the 5-year overall survival, disease-free survival, and locoregional failure-free survival rates were 86 % [95 % confidence interval (CI), 74-99 %], 59 % (95 % CI, 42-77 %), and 90 % (95 % CI, 79-100 %), respectively. Late toxicities of grade 3 pleural effusion in 2 patients, grade 4 pericardial effusion in 1 patient, and grade 5 pneumonitis in 1 patient were observed. Metachronous esophageal cancer was observed in 8 patients (22 %). Among them, 6 patients with mucosal legions were salvaged by endoscopic resection. CONCLUSION: Our long-term results of concurrent chemoradiotherapy (CCRT) for patients with esophageal submucosal cancer showed acceptable toxicities and favorable locoregional control and survivals while maintaining organ preservation.

The postirradiation incidence of cavernous angioma is higher in patients with childhood pineoblastoma or primitive neuroectodermal tumors than medulloblastoma.

PURPOSE: The purpose of this study is to investigate the incidence of cavernous angioma (CVA) in long-term survivors of childhood embryonal tumors treated by cranial irradiation. MATERIALS AND METHODS: Between 1990 and 2012, we treated 25 patients (13 males, 12 females) with embryonal tumors (17 medulloblastomas, 5 primitive neuroectodermal tumors (PNET), 3 pineoblastomas) with craniospinal irradiation. Follow-up ranged from 15.5 to 289.9 months, the irradiation dose to the whole neural axis from 18 to 36 Gy, and the total local dose from 49.6 to 60 Gy. All patients underwent follow-up magnetic resonance imaging (MRI) studies at least once a year, and the diagnosis of posttreatment CVA was based solely on MRI findings. RESULTS: At the time of this writing, 18 were alive and free of the recurrence of the original disease or the development of secondary neoplasms other than CVA; another 2 were alive with medulloblastoma or diffuse astrocytoma. Posttreatment, 14 patients developed CVAs in the course of a median of 56.7 months; 13 of these presented with multiple CVAs. Patients who underwent radiation therapy (RT) at an age younger than 6 years developed multiple CVAs significantly earlier than those treated at a later age (p = 0.0110). Patients with PNET or pineoblastoma developed Zabramski type 1 and 2 CVA significantly earlier than did medulloblastoma patients (p = 0.0042). CONCLUSION: We attribute the high rate of post-RT CVA in our long-term follow-up study of pediatric patients to the delivery of cranial irradiation for embryonal tumors, especially PNET and pineoblastoma, and recommend the regular, long-term follow-up of patients whose embryonal tumors were treated by cranial irradiation.

Cerebral blood flow in transient hypothyroidism after thyroidectomy: Arterial spin labeling magnetic resonance study.

OBJECTIVE: Our purpose was to apply arterial spin labeling (ASL) magnetic resonance imaging (MRI) to characterize regional cerebral blood flow (rCBF: the CBF values at each voxel / the subject's mean global flow) in patients with transient hypothyroidism after thyroidectomy. METHODS: Our study included 27 patients who had undergone total thyroidectomy due to thyroid cancer and pre-131I therapy and 24 controls. Patients were evaluated at two points in time: before and after thyroxine replacement. The assessments for the patients and controls consisted of evaluation of ASL of the brain and the severity of depression using 21-question Beck Depression Inventory (BDI). The assessments for the patients also included thyroid hormone lebel. We performed the comparison of rCBF between patients and controls, and investigated the association between rCBF in hypothyroid patients and thyroid hormone level and BDI score. RESULTS: Hypothyroid patients showed a significantly lower rCBF in the cerebellum, the left thalamus and some regions, and showed a significantly higher rCBF in the bilateral frontal gyri and some regions. After thyroxine replacement, patients showed a significantly lower rCBF mostly in the right frontal lobe, and showed a significantly higher rCBF in the left frontal and parietal lobes, although the degree of rCBF changes was lower after thyroxine replacement. In the hypothyroid patients, significant positive relationships were found between free T3 and the rCBF (p<0.05 corrected for FDR). CONCLUSIONS: This study revealed alterations of rCBF in patients with transient hypothyroidism. ASL is helpful for understanding of the effects of hypothyroidism on the brain.

Case reports of portal vein thrombosis and bile duct stenosis after stereotactic body radiation therapy for hepatocellular carcinoma.

The aim of this study was to evaluate portal vein and bile duct toxicity after stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC). We retrospectively reviewed 63 patients who were administrated SBRT once for HCC. The prescribed doses were from 48 Gy in four fractions to 60 Gy in eight fractions. Portal vein thrombosis and bile duct stenosis were evaluated. The dose received by 2% of the volume (D2 ) of the portal vein and bile duct was calculated. Portal vein thrombosis was observed in three patients (4.8%). Common points of these patients were Child-Pugh class B and D2 of the portal vein 40 Gy or more (BED3 ≥200 Gy). Bile duct stenosis was observed in one patient (1.6%). The patient had a history of cholangiocarcinoma and left hepatic lobectomy. Portal vein thrombosis may be necessary to be considered when SBRT for HCC is administrated to patients in higher Child-Pugh class with higher D2 of the portal vein.

Japanese structure survey of high-precision radiotherapy in 2012 based on institutional questionnaire about the patterns of care.

OBJECTIVE: The purpose of this study was to clarify operational situations, treatment planning and processes, quality assurance and quality control with relevance to stereotactic radiotherapy, intensity-modulated radiotherapy and image-guided radiotherapy in Japan. METHODS: We adopted 109 items as the quality indicators of high-precision radiotherapy to prepare a questionnaire. In April 2012, we started to publicly open the questionnaire on the website, requesting every institution with radiotherapy machines for response. The response ratio was 62.1% (490 out of 789 institutions responded). RESULTS: Two or more radiotherapy technologists per linear accelerator managed linear accelerator operation in ∼90% of the responded institutions while medical physicists/radiotherapy quality managers were engaged in the operation in only 64.9% of the institutions. Radiotherapy certified nurses also worked in only 18.4% of the institutions. The ratios of the institutions equipped for stereotactic radiotherapy of lung tumor, intensity-modulated radiotherapy and image-guided radiotherapy were 43.3, 32.6 and 46.8%, respectively. In intensity-modulated radiotherapy planning, radiation oncologists were usually responsible for delineation while medical physicists/radiotherapy quality managers or radiotherapy technologists set up beam in 33.3% of the institutions. The median time required for quality assurance of intensity-modulated radiotherapy at any site of brain, head and neck and prostate was 4 h. Intensity-modulated radiotherapy quality assurance activity had to be started after clinical hours in >60% of the institutions. CONCLUSIONS: This study clarified one major issue in the current high-precision radiotherapy in Japan. A manpower shortage should be corrected for high-precision radiotherapy, especially in the area relevant to quality assurance/quality control.

Pilot study of stereotactic body radiation therapy combined with transcatheter arterial chemoembolization for small hepatocellular carcinoma.

BACKGROUND/AIMS: We retrospectively evaluated the local tumor control and safety of transcatheter arterial chemoembolization (TACE) followed by stereotactic body radiation therapy (SBRT) for small hepatocellular carcinoma (HCC) in this pilot study. METHODOLOGY: Twenty-eight patients not for the indication of hepatectomy or ablation procedures were enrolled in this study. Eligible criteria was as followed: i) less than 3 hypervascular HCC nodules, each up to 30 mm in diameter; ii) not suitable for the hepatic resection or ablative therapy; iii) Child-Turcotte-Pugh (CTP) score < or = 7. SBRT was performed within 1-2 months after TACE. Treatment efficacy was evaluated, according to the Response Evaluation Criteria in Cancer of the Liver (RECICL). RESULTS: The median local tumor control time was not reached. The 1-year cumulative local tumor control rate was 96.3%. The median disease-free survival time was 18 months. The 1- year cumulative overall survival rate was 92.6%. One patient (3.6%) died due to intrahepatic ectopic multiple recurrence and systemic metastasis and one (3.6%) due to cerebral hemorrhage. No patients experienced severe acute hematologic or physical toxicity or radiation induced liver damage. CONCLUSIONS: Our study demonstrated SBRT combined with TACE is a safe and effective modality of the locoregional therapy for small primary HCC.