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Purpose: To introduce a respiratory motion management technique, so called quasi-breath-hold (QBH) technique and evaluate its feasibility. As a hybrid technique combining free-breathing-based gating (denoted as gating for convenience) and breath-hold (BH), the QBH is designed to overcome typical limitations existing in either one such as phase-shift, residual motion, complexity, and discomfort. Methods: The QBH is realized using an audio-visual biofeedback system (AVBFS) and a respiratory motion management program (RMMP). The AVBFS, consisting of two infra-red stereo cameras and a head mounted display, monitors respiratory motion and provides dynamic feedback to patients. The RMMP establishes a personalized respiration model based on deep free breathing. The model is further processed to generate a QBH model by inserting a short breath-hold period into the end point of the-end-of-expiration phase. Then the patient is guided to follow the QBH model through the AVBFS. A simulation study with ten volunteers was performed to evaluate the feasibility of the proposed technique. In the simulation, an in-house developed macro program automatically controlled the QBH procedure to virtually deliver an intensity modulated radiation therapy(IMRT) plan. For each volunteer subject, three QBH maneuvers with different breath-hold times of 3, 5, and 7s (denoted as QBH3s, QBH5s, and QBH7s, respectively) and a conventional gating maneuver with 30% duty cycle (for comparison purpose) were applied. External respiration motion signals obtained during the gating window were analyzed to obtain mean absolute error (MAE) between the measured and guiding curve, mean absolute deviation (MAD) of the measured curve, and an inverse uncertainty time histogram (IUTH). Results: Every volunteer successfully performed all of the four maneuvers (1 gating and 3 QBH patterns). The average treatment times were 466.8, 452.3, and 430.8 s for the QBH3s, QBH5s, and QBH7s, respectively, compared to 530.4 s for the gating technique. The mean absolute errors between measured and guiding curve during the gating window were 0.9 ± 0.7, 0.8 ± 0.6, 0.7 ± 0.6, and 0.6 ± 0.7 mm for the gating, QBH3s, QBH5s, and QBH7s, respectively. The mean absolute deviations of the measured curve during the gating window were 0.7 ± 0.7, 0.5 ± 0.5, 0.5 ± 0.4, and 0.5 ± 0.6 mm for the gating, QBH3s, QBH5s, and QBH7s, respectively. In the analysis of the IUTH during the gating window, the QBH simulations showed similar (QBH3s) or less (QBH5s and QBH7s) motion uncertainties compared to the gating simulation. Conclusions: The proposed QBH technique with personalized audio-visual biofeedback was feasible for respiratory motion management. It showed equivalent or less motion uncertainty and shorter treatment time than the conventional free-breathing-based gating technique did. The technique is expected to optimally compromise between patient comfort and treatment efficiency.

The prognosis of intracranial germinoma producing the human chorionic gonadotropin (hCG) is controversial due to limited information. We undertook a retrospective analysis to determine whether this type of tumor has similar clinical course and prognosis to hCG non-secreting germinoma. Thirty-one histologically confirmed intracranial germinoma patients who had pretreatment hCG examination in serum/CSF were treated with radiotherapy between 1980 and 1996. hCG level was measured by immunoradioassay of beta subunit of hCG. Six patients had elevated serum hCG levels and were defined as having hCG secreting germinoma. All except three patients received craniospinal axis irradiation. The follow-up ranged from 19-175 months with a median of 63 months. hCG secreting germinoma accounted for 19% of intracranial germinoma cases. Elevated hCG levels ranged from 39-260 IU/l in serum. No difference was found between hCG non-secreting germinoma and hCG secreting germinoma in terms of patient or treatment characteristics. There was no recurrence among the six hCG secreting germinoma patients. The 5-year overall and disease-free survival rates were 96% for patients with hCG non-secreting germinomas and 100% for the patients with hCG secreting germinomas. The survival difference was not significant (p = 0.59). Our results suggest that elevated level of hCG did not result in any differences in the clinical characteristics or survival after radical radiotherapy in histologically confirmed intracranial germinoma.

A thiol-dependent antioxidant protein (HRPRP) was previously reported as a predominant antioxidant protein in human red blood cell (RBC). The analysis of amino acid sequence of HRPRP with those of human PRP-like gene products indicates that HRPRP is identical to brain PRP (HPRP). This protein act as a peroxidase linked to thioredoxin (Trx)/thioredoxin reductase (TR). Until now, there was no evidence for Trx/TR system in RBC. The existence of the Trx/TR system in RBC was immunologically determined. A 58-kDa protein showing TR activity was partially purified from human RBC and characterized. Our results reveal that HRPRP act as a new type of peroxidase supported by Trx/TR system in human RBC.

Purpose: To introduce a respiratory motion management technique, so called quasi-breath-hold (QBH) technique and evaluate its feasibility. As a hybrid technique combining free-breathing-based gating (denoted as gating for convenience) and breath-hold (BH), the QBH is designed to overcome typical limitations existing in either one such as phase-shift, residual motion, complexity, and discomfort. Methods: The QBH is realized using an audio-visual biofeedback system (AVBFS) and a respiratory motion management program (RMMP). The AVBFS, consisting of two infra-red stereo cameras and a head mounted display, monitors respiratory motion and provides dynamic feedback to patients. The RMMP establishes a personalized respiration model based on deep free breathing. The model is further processed to generate a QBH model by inserting a short breath-hold period into the end point of the-end-of-expiration phase. Then the patient is guided to follow the QBH model through the AVBFS. A simulation study with ten volunteers was performed to evaluate the feasibility of the proposed technique. In the simulation, an in-house developed macro program automatically controlled the QBH procedure to virtually deliver an intensity modulated radiation therapy(IMRT) plan. For each volunteer subject, three QBH maneuvers with different breath-hold times of 3, 5, and 7s (denoted as QBH3s, QBH5s, and QBH7s, respectively) and a conventional gating maneuver with 30% duty cycle (for comparison purpose) were applied. External respiration motion signals obtained during the gating window were analyzed to obtain mean absolute error (MAE) between the measured and guiding curve, mean absolute deviation (MAD) of the measured curve, and an inverse uncertainty time histogram (IUTH). Results: Every volunteer successfully performed all of the four maneuvers (1 gating and 3 QBH patterns). The average treatment times were 466.8, 452.3, and 430.8 s for the QBH3s, QBH5s, and QBH7s, respectively, compared to 530.4 s for the gating technique. The mean absolute errors between measured and guiding curve during the gating window were 0.9 ± 0.7, 0.8 ± 0.6, 0.7 ± 0.6, and 0.6 ± 0.7 mm for the gating, QBH3s, QBH5s, and QBH7s, respectively. The mean absolute deviations of the measured curve during the gating window were 0.7 ± 0.7, 0.5 ± 0.5, 0.5 ± 0.4, and 0.5 ± 0.6 mm for the gating, QBH3s, QBH5s, and QBH7s, respectively. In the analysis of the IUTH during the gating window, the QBH simulations showed similar (QBH3s) or less (QBH5s and QBH7s) motion uncertainties compared to the gating simulation. Conclusions: The proposed QBH technique with personalized audio-visual biofeedback was feasible for respiratory motion management. It showed equivalent or less motion uncertainty and shorter treatment time than the conventional free-breathing-based gating technique did. The technique is expected to optimally compromise between patient comfort and treatment efficiency.