Effect of inhomogeneity in a patient's body on the accuracy of the pencil beam algorithm in comparison to Monte Carlo.

The pencil beam algorithm (PBA) is reasonably accurate and fast. It is, therefore, the primary method used in routine clinical treatment planning for proton radiotherapy; still, it needs to be validated for use in highly inhomogeneous regions. In our investigation of the effect of patient inhomogeneity, PBA was compared with Monte Carlo (MC). A software framework was developed for the MC simulation of radiotherapy based on Geant4. Anatomical sites selected for the comparison were the head/neck, liver, lung and pelvis region. The dose distributions calculated by the two methods in selected examples were compared, as well as a dose volume histogram (DVH) derived from the dose distributions. The comparison of the off-center ratio (OCR) at the iso-center showed good agreement between the PBA and MC, while discrepancies were seen around the distal fall-off regions. While MC showed a fine structure on the OCR in the distal fall-off region, the PBA showed smoother distribution. The fine structures in MC calculation appeared downstream of very low-density regions. Comparison of DVHs showed that most of the target volumes were similarly covered, while some OARs located around the distal region received a higher dose when calculated by MC than the PBA.

SU-E-J-165: Development of a Low-Cost and Clinically Available Patient Intrafraction Motion Monitoring System.

PURPOSE: We have developed a flexible system in order to monitor the intrafraction motion. The purpose of our study is to extend the monitoring system to clinically available system with low cost. METHODS: Our system is composed of a standard web camera with a low-cost and 8x magnitude telescope, a personal computer with our in-house software and a specific marker box. The telescopic lens was attached with the web camera to extend more effective distance of the measurement in order to avoid patient's interference. The dynamic calibration algorithm was developed to take into account patient's rotation during treatment in order to measure the intrafraction motion more accurately. Tracking three markers simultaneously based on a template matching technique using parallel CPU computing was performed to measure the intrafraction motion with dynamic calibration. To evaluate our new system, a respiratory motion QA phantom with 10 mm-amplitude was used in order to measure the amplitudes under the different angles of web camera setting (0 to 50 degree, 5 degree step) using our system and Varian Real-Time Position Management Respiratory Gating (Varian-RPM) System. The results of our system were compared with the results of Varian-RPM System. RESULTS: The result of the amplitudes measured by our system and Varian RPM-System are 10.2±0.3 mm and 10.3±0.1mm at the angle of 0 deg., respectively. The values of both systems were within the tolerance value of AAPM Task group 142. The results of the amplitude of our system and Varian-RPM system were 10.2±0.3mm and 10.4±0.1mm, respectively, while the angle was changed. Under the parallel CPU computing, the calculation time to measure the position of the marker was about 50msec including the latency. CONCLUSIONS: Our proposed system could have clinically acceptable accuracies. The system would be contributed broadly to improve the treatment accuracy because of low-cost installation of it.

Dosimetric evaluation of nuclear interaction models in the Geant4 Monte Carlo simulation toolkit for carbon-ion radiotherapy.

We tested the ability of two separate nuclear reaction models, the binary cascade and JQMD (Jaeri version of Quantum Molecular Dynamics), to predict the dose distribution in carbon-ion radiotherapy. This was done by use of a realistic simulation of the experimental irradiation of a water target. Comparison with measurement shows that the binary cascade model does a good job reproducing the spread-out Bragg peak in depth-dose distributions in water irradiated with a 290 MeV/u (per nucleon) beam. However, it significantly overestimates the peak dose for a 400 MeV/u beam. JQMD underestimates the overall dose because of a tendency to break a nucleus into lower-Z fragments than does the binary cascade model. As far as shape of the dose distribution is concerned, JQMD shows fairly good agreement with measurement for both beam energies of 290 and 400 MeV/u, which favors JQMD over the binary cascade model for the calculation of the relative dose distribution in treatment planning.

Near-infrared spectrophotoscopy of finger venules in assessment of autonomic dysfunction.

The authors evaluated morphologic changes in the venules of the finger using near-infrared spectrophotoscopy in patients with autonomic dysfunction, such as familial amyloidotic polyneuropathy and multiple-system atrophy. Abnormalities of the venules, such as tortuosity, irregular venous caliber, and microaneurysm-like change, and a linear negative correlation between the degree of orthostatic hypotension and the degree of vasoconstriction of the venules were observed.

[Assessment of prognosis and p 53 mutations in patients with multiple tumors of the lung; intrapulmonary metastasis or double primary cancers?].

To assess whether a satellite lesion in the primary-tumor lobe is intrapulmonary metastasis from primary cancer (pm 1) or they are double primary lung cancers, we examined the postoperative prognosis of patients with pm 1 and the p 53 genetic differentiation between a satellite lesion and a primary lesion. Of 772 consecutive patients with N0-2M0 non-small cell lung cancer who underwent surgical resections between 1979 and 2000, 31 patients had a satellite lesion in the primary-tumor lobe. The 5-year survival rate was 26.3% in the pm 1 (+) T 4 group (n = 37), 14.7% in the pm 1 (-) T 4 group (n = 43), and 32.5% in the T 3 group (n = 132), suggesting that pm 1 cases should be classified as T 3. We examined 16 of 37 patients with pm 1 for mutations of the p 53 gene occurring exons 5 through 8 by the fluorescence-based polymerase chain reaction single-strand conformation polymorphism. Seven of the 16 patients analyzed had at least one p 53 mutations in their tumors. The mutational status of the p 53 gene was discordant in 5 patients, suggesting they were double primary lung cancers. The mutational status including DNA sequencing of the p 53 gene was concordant in 2 patients, suggesting they were intrapulmonary metastases. It remains arguable in the TNM staging system whether a satellite lesion in the primary-tumor lobe is intrapulmonary metastasis from primary cancer or they are double primary lung cancers.

[Medical cost analysis of neoadjuvant chemotherapy for advanced tongue and oropharyngeal cancer].

We performed a medical cost analysis on the use of neoadjuvant chemotherapy (NAC) in multi-modal treatments for advanced tongue and oropharyngeal cancer. Twenty-two patients with stage III and IV squamous cell carcinoma of the tongue and oropharynx were enrolled in this study. Two courses of NAC with CDDP and 5-FU followed by radiotherapy were performed in 13 patients who showed a partial response or a complete response after the first course of NAC. The doses of radiation were 60 Gy for 4 patients (rad. group), and 72 Gy for 9 patients who received hyperfractionated radiotherapy with simultaneous Carboplatin (HF rad. group). Radical surgery was performed in 9 patients who did not respond to NAC (surg. group). The mean duration of hospital stay was 89.3 days for the rad. group, 92.0 days for the HF rad. group, and 113.3 days for the surg. group. The mean medical cost was 238,700 points for the rad. group, 264,846 points for the HF rad. group, and 459,468 points for the surg. group. The mean amounts and percentages of cost for NAC were 39,473 points and 16.1% for the rad. group, 44,802 points and 16.9% for the HF rad. group, and 23,451 points and 5.1% for the surg. group. The mean amounts of cost for NAC including examination costs and nursing costs for chemotherapy were 130,196 points and 54.5% for the rad. group, 150,046 points and 55.7% for the HF rad. group, and 113,839 points and 24.8% for the surg. group. The cost of NAC accounted for half of the total cost of chemo-radiation treatment for functional preservation. The duration of the hospital stay was prolonged by NAC, which accounted for a quarter of the total cost for the surg. group. Survival benefits are considered in the analysis of treatment cost-effectiveness for head and neck cancers. In the future, QOL, which is defined as the utility achieved as a result of multi-modal treatments, should also be analyzed along with survival benefits. Cost-utility analyses should include quality-adjusted life years, based upon the cost identification results of our analysis for NAC, to evaluate the efficacy of NAC in multi-modal treatments for head and neck cancers.

A 2D/3D hybrid PET scanner with rotating partial slice-septa and its quantitative procedures.

This paper presents a PET scanner capable of acquiring projection data in three-dimensional (3D) and two-dimensional (2D) modes simultaneously. The scanner has rotating partial slice-septa, and coincidence events are stored as 2D data or as 3D data depending on whether the lines of response are collimated by the septa or not. 68Ge/Ga rod sources can be set on the rotating septa, and a transmission scan for attenuation correction is performed in the 2D mode. The scanner allows simultaneous 3D-emission/2D-transmission scanning or post-injection transmission scanning with little cross-talk. A blank scan for detector normalization is also performed with the rotating rod sources in the 2D mode, from which we can derive the normalizing factors in both modes. The 3D/2D difference method is available for scatter correction, even in a dynamic study where the source distribution is changing. A 'summation method' is proposed as a new image reconstruction algorithm, in which the high- and low-frequency components of images are reconstructed from the 3D and 2D data respectively. In this method, most of the scatter contribution in the 3D data is removed by high-pass filtering, not by subtracting estimated scatter distribution, and hence the method is expected to be robust for scatter from outside the axial field of view. Computer simulations revealed that the rotating partial septa offer a single-scatter to true ratio similar to that of the conventional full septa if the depth of the partial septa is properly lengthened, with a small increase in multiple scattering.

[Clinical quality assurance at institutions according to a patterns of care study. Japanese PCS Working Group].

The clinical quality assurance (QA) of an institution is important in any multiinstitutional prospective study. Patterns of Care Study (PCS) is a well-known study for QA activity in the United States. PCS is a nationwide retrospective study done by two-staged cluster sampling of institutions and patients and external audits. After data are accumulated, National averages on various survey items are calculated as a QA measure. In 1996, PCS was imported into the radiation oncology field in Japan with the support of the Ministry of Health and Welfare. Preliminary results showed significant differences in treatment process, structure, and preliminary outcome according to the stratification of institutions. These data can be useful in improving the structure and process at the institutional as well as the national level. PCS will also clarify the dissemination of positive clinical results into national practice.

Prospective randomized study of antibiotic prophylaxis for nonlaparotomy surgery in benign conditions.

BACKGROUND: Although postoperative infections continue to be a major problem in gynecologic surgery, there is still no consensus on the efficacy of antibiotic prophylaxis. METHODS: This prospective randomized trial was conducted to investigate the prevention of major operating site infections after nonlaparotomy surgery, with treatment regimens as follows: the first group of patients received 2 g of intravenous cefotiam dihydrochloride (CTM) on the induction of anesthesia, while the second group received 100 mg of oral cefpodoxime proxetil (CPDX- PR) twice daily, from day 0 to day 2. RESULTS: Nineteen of the 207 patients enrolled developed postoperative infections diagnosed by our simple criteria for postoperative infection. The frequency of febrile morbidity was not significantly less in patients who received CTM (9 cases; 8.6%) as compared with those in the CPDX-PR group (10 cases; 9.8%) (p = 0.56). CONCLUSION: The administration of oral CPDX-PR (100 mg, twice daily, for 3 days) appears to be a safe, cost-saving, convenient prophylaxis which reduces overall expense.

[A nationwide investigation needs for rehabilitation of schizophrenic outpatients--the patients' attribute and actual conditions of living].

In Japan we are very short of community resources for persons with mental disability. The authors, a board of resettlement, thought patients' actual conditions of living and needs for rehabilitation to let them live in the community had to be evaluated. Then in March 1993 the actual conditions of living and needs for rehabilitation of schizophrenic outpatients were investigated nationally. This article is the report on the patients' actual conditions of living. Investigation papers were sent to 358 institutions (286 hospitals and 72 clinics) which agreed to cooperate with the investigation. The 5186 investigation papers were received from 313 institutions. All of the papers except 18, which were lack of their ages, were analyzed. All of the schizophrenic outpatients, who consulted psychiatrists on one day during investigation, were considered objects of this research. Those who consented were included the research and psychiatrists filled in investigation papers. These institutions had a policy of intensive social resettlement activities and so on. Male patients were 55% and females were 45%. There were patients in the forties and females were older than males. Thirty-nine percent of them had been hospitalized once or twice. Thirty-four percent of them had been hospitalized for less than one year. Eighteen percent of them had not been hospitalized. Fifty percent of patients answered there was no friend and acquaintance, and had a tendency to stand alone. Fifty-three percent of patients lived with their parents, 21% with their spouses, and 17% alone. But 32% of females lived with their husbands. Sixteen percent worked for full-time jobs, 8% worked part-time jobs, 12% attended day care center 4% went to sheltered-workshops and only 1% went to rehabilitation-workshops for outpatients. While 13% didn't have a right to receive disability pension, the sources of income were job (30%), disability pension (30%), and welfare benefits (12%). Regarding the ability for living, both socially independent patients and daily independent were 36%. On the other hand, patients who needed support in daily life were 27%. This ability wasn't related to sex and age significantly (chi-square test). It is clear most of the patients were in isolation and depended on their families, so they needed support in income, accommodation and daily life.

Early assessment of reperfusion therapy using cardiac troponin T.

OBJECTIVES: The purpose of this study was to investigate the utility of cardiac troponin T for early assessment of reperfusion therapy. BACKGROUND: Several biochemical markers are used for early noninvasive detection of reperfusion during intravenous thrombolytic therapy. However, cardiac troponin T, a new myocardial-specific marker, has not been used previously for this purpose. METHODS: We measured troponin T and creatine kinase, MB isoenzyme (CK-MB) levels in 38 patients with acute myocardial infarction whose infarct-related artery was totally occluded before reperfusion therapy. Subjects comprised 14 patients with successful angioplasty (group 1), 12 patients with successful thrombolytic therapy (group 2) and 12 patients with unsuccessful attempted reperfusion (group 3). Blood samples were taken every 15 min, and coronary angiography was performed every 5 to 8 min until 60 min after reperfusion (groups 1 and 2) or after the initiation of treatment (group 3). We calculated the increase in troponin T (delta troponin T) and CK-MB (delta CK-MB) 60 min after treatment was initiated and 60 min after reperfusion in groups 1 and 2. RESULTS: Mean (+/- SD) delta troponin T and delta CK-MB levels were 9.35 +/- 7.83 ng/ml and 125 +/- 83 mU/ml in group 1 and 3.23 +/- 3.08 ng/ml and 130 +/- 137 mU/ml in group 2, respectively, 60 min after treatment and were 10.1 +/- 8.35 ng/ml and 131 +/- 84 mU/ml in group 1 and 6.84 +/- 8.30 ng/ml and 158 +/- 146 mU/ml in group 2, respectively, 60 min after reperfusion. These values were significantly higher than those 60 min after treatment in group 3: 0.16 +/- 0.19 ng/ml and 10 +/- 9 mU/ml, respectively. The predictive accuracy for detecting reperfusion using a threshold value of 0.50 ng/ml of delta troponin T and 25 mU/ml of delta CK-MB was 100% in group 1 and 92% in group 2 60 min after treatment, respectively. There was significant correlation between delta troponin T and delta CK-MB. CONCLUSIONS: Serial measurements of cardiac troponin T as well as of CK-MB are useful for early assessment of reperfusion therapy.

Early detection of coronary reperfusion by rapid assessment of plasma myoglobin.

We assayed plasma myoglobin and creatine kinase to elucidate the usefulness of rapid assessment of myoglobin for detecting coronary reperfusion in 31 patients with acute myocardial infarction. Reperfusion was achieved in 20 patients by thrombolytic therapy or angioplasty, and it was not in 11 patients. Blood sampling was performed before and 43 +/- 15 (+/- SD) min after the start of treatment. In the reperfused group, blood samples were obtained before and 26 +/- 10 min after reperfusion. Myoglobin was assayed by a new quantitative test based on latex agglutination turbidimetry which required an assay time of 10 min. After treatment, the rate of increase of plasma myoglobin was significantly higher than that of plasma creatine kinase in the reperfused group (9.7 +/- 9.5 and 2.8 +/- 1.6-fold), but not in the occluded group (1.8 +/- 0.6 and 1.5 +/- 0.3-fold). When a 3.0-fold or greater increase in myoglobin (1.9-fold or greater increase in creatine kinase) was taken as evidence of coronary reperfusion, the sensitivity and specificity were 95% and 100% (70% and 82% in creatine kinase), respectively. In conclusion, using the rate of increase of myoglobin, as measured by latex agglutination turbidimetry, coronary reperfusion can be diagnosed within 1 h after reperfusion.