This paper is based on my invited talk at the JASTRO Brachytherapy Subcommittee meeting in June of 2003 in Tokyo. The talk materials are derived from the presentation of low dose-rate (LDR) gynecologic cancer therapy given at the University of California, Davis Cancer Center by Dr. Fritz Lerma of Mallinckrodt Institute of Radiology (MIR), Washington University, St. Louis. For more than 5 years, a brachytherapy program has been pushed forward at MIR and the University of California at San Francisco. In particular, Dr. Jeff Williamson of MIR, now at the Medical College of Virginia, emphasized the importance of CT imageguided brachytherapy treatment, 3D simulation of anatomy and applicators, and dose calculations based on Monte Carlo applicator simulations. The use of CT images has differentiated the treatment modalities from the past in that it allows more quantitative data analysis and provides more accurate dose distribution information. Dr. Williamson has single-handedly developed the frontier of gynecologic brachytherapy in the U.S. Dr. Lerma was his disciple and worked with him for two years during the program development period. Therefore, I believe Dr. Lerma's materials reproduced here with his permission belong in the forefront of the brachytherapy treatment approach to gynecologic cancers in North America.
This paper begins with an Introduction followed by the LDR Gynecologic brachytherapy program, and Motivations to push CT image-guided treatment planning forward at Mallinckrodt. As a practical example of 3 dimensional image-guided radiotherapy, this paper will elaborate on the accurate matching of applicator contours delineated in a CT space and Monte Carlo simulation methods. The use of CT and Monte Carlo simulations of applicator in a CT space allows treatment plan dose calculations solely on the basis of the Monte Carlo method if the full Monte Carlo calculations and dose measurements by 3 dimensional (3D) water phantom scan are in agreement. The conventional 2D single source superposition method does not take into account the presence of applicators. Therefore, the scattering and absorption of photons produced by the nearby sources are not accounted for. As a result it shows some dose deviations, in particular, near the source.
At the end, this paper introduces positron emission tomography (PET) image-guided brachytherapy treatment planning^{1), 2)} . This modality is compared with the conventional 2D image-guided treatment plans. The PET images are known to reflect more physiologic information than CT images, even though the CT images provide better geometrical resolution than PET. The PET-based 3D treatment planning certainly belongs to the frontier of 3D image-guided brachytherapy treatment planning and delivery. As proved from the prostate study by magnetic resonance spectroscopy (MRS) ³⁾ , the tumor cell concentration within the tumor is not necessarily uniform. In this respect, though not proven yet, the PET images may shed some light on the tumor cell distribution for the gynecologic (GYN) cancer.

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Clinical results of HDR brachytherapy show better than those of the LDR one. Most radiation biologists could not predict these results. At the beginning, they presumed that LDR brachytherapy was one of the best treatment modalities for cancers of the uterine cervix, mobile tongue and others. They criticized that HDR brachytherapy was a harmful modality from a biological standpoint. They proposed equations such as Nominal Standard Dose (NSD), Time Dose and Fractionation factor (TDF), Cumulative Radiation Effect (CRE) to be mandatory for the biological dose-rate conversion from LDR to HDR brachytherapy. However, these equations had not included the parameter of treatment volume that was one of the most valuable factors. Moreover, these equations consisted of parameters that were obtained from clinical results, not from the biological experiments. Instead of these biological equations, the new concept of the linear-quadratic (LQ) model was proposed. Effects of dose-rate for LDR brachytherapy and fractionation for HDR could be considered, however that of treatment volume could not be considered. In the classical Manchester system for brachytherapy, dose-rate was mainly affected by the treatment volume, because of the standard application of the Radium employed. The original prescribed dose in LDR brachytherapy of interstitial and intracavitary technique for cancers of the mobile tongue and uterine cervix using Paris and Manchester systems was 60 Gy over 144 to 168 hours. Although the prescribed dose was apparently changed by dose-rate, however, the variety of dose rate originally resulted from the size of the treatment volume in clinical practice. In addition, the ⁶⁰Co from a high intensity source and the new ¹⁹²Ir micro-source of relatively short half-life changed these rules. However, these sources enable us to use HDR brachytherapy with more accuracy. Now we need a new biological model with original treatment parameters obtained from the modern HDR brachytherapy itself.

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When a medical accident happens there are instances where patients, their relatives or the bereaved sue for compensation and this is referred to as “medical conflict.” If a medical conflict, the patient's side goes to court and this is “medical litigation”. In a medical accident happened, there is an inquiry as to whether or not a civil act, and/or criminal act, and/or the administrative responsibility has been committed. The purpose of medical risk management is investigation into the cause, building a prevention system, and decreasing accidents.

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Purpose: To improve the local control of T2-stage glottic carcinomas, we performed concomitant chemoradiation therapy with UFT (uracil and tegafur) and low dose CDDP. The predictive value of MR findings was also evaluated.
Methods and Materials: Thirty six patients with T2NO-stage glottic carcinomas were included in this study. Tumors adjacent to the thyroid cartilage on MRI were classified as “adjacent”, and undetectable tumors or tumors separate from the cartilage were classified as “intact”. Radiation therapy with 64 Gy/32 fractions was delivered by 4 MV linear accelerator. Intravenous infusion of CDDP (4 mg/m2) and oral administration of UFT (450 mg/body) were continued concomitantly from day one of irradiation for four weeks. Kaplan-Meier methods were used to estimate the time to local recurrence distribution. Differences were determined using log-rank tests for univariate analysis.
Results: No severe acute and late adverse effects (grade 3 or more) were observed. Two-year local control rate with chemoradiation therapy was 82%. According to MR findings, local control rates were 95% for intact lesions (n=20) and 68% for adjacent lesions (n=16) (p=0.0249).
Conclusion: Concomitant chemoradiation therapy with UFT and low dose CDDP was considered to be effective for T2-stage glottic carcinomas. However, the results were not enough for tumors adjacent to the thyroid cartilage on MRI.

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In the U.S. and Europe, brachytherapy by permanent implantation of radioactive seeds, ¹²⁵I or ¹⁰³Pd is often performed for treatment of prostate cancer. In Japan, in March 2003, the Ministry of Health, Labor and Welfare permitted the use of ¹²⁵I seeds under the observance of the related laws and discharge criteria. With a view to popularize ¹⁰³Pd seeds like ¹²⁵I, we implanted ¹⁰³Pd seeds into the prostate site of a humanoid body phantom, measured dose equivalent rate around it, and obtained basic data on which discharge criteria are based upon. We also calculated the exposure dose of carers, based on obtained data.
As a result, the 1 cm dose equivalent rate, considering absorption at the prostate or other organs, was calculated 0.00006μSv·m²·MBq^-1·h^-1, and the exposure dose of carers was sufficiently below the dose limitation of IAEA or NRC.
Therefore, for the use of ¹⁰³Pd seeds, there is almost no need to be concerned about the risk of radiation exposure to people around the patient, and its safety seems superior to ¹²⁵I seeds. We consider outpatient treatment is possible under the existing law, which is a standard treatment pattern in the U.S. and Europe.

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Purpose: By means of quantifying the nonuniform distribution of pulmonary perfusion in Lung Perfusion Scintigraphy SPECT (Single Photon Emission Tomography), which is called “SPECT” for short, we evaluated the degree of functional impairment of pulmonary perfusion in non-operated lung cancer patients treated by the radiotherapy.
Materials and Methods: Sixty-eight patients with non-operated lung cancer treated with radiotherapy, and who either received or did not receive chemotherapy, from February, 1996 to August, 2002, were examined using SPECT within 6 weeks prior to, or within 2 weeks following radiotherapy. This group was called “irradiated lung cancer patients”. Twenty-six patients, who were called “follow-up irradiated lung cancer patients”, were reexamined within four weeks after radiotherapy. On the other hand, 323 patients without lung cancer, who were subdivided into four groups; pulmonary, cardiac, cardio-pulmonary, and noncardiopulmonary. The SPECT was examined in the supine position after infusing Tc-99m-MAA, 185 MBq in a bolus, mainly into an antecubital vein with the patient's arm elevated. From reconstructed SPECT images, the volume of lung as a whole calculated at 10 % of thresholds was assumed to be the “Baseline Lung Perfusion Volume” (BPV), and the functional volume rates were calculated in 10 % threshold widths from 10 % to 100 % of the threshold. Assuming the total absolute differences in functional volume rate between each subject and the control to be the distribution index of the lung as a whole (D index), we quantified the degree of nonuniform distribution of the lung as a whole in each subject. In the same way, the distribution index of the left or right lung respectively was calculated as D₁ or D_r index assuming the volume of left or right lung were calculated at 10 % of the threshold as left or right BPV and calculating the functional volume rates of each lung in 10% threshold widths from 10 % to 100 % of the threshold.
Results: The D index of irradiated lung cancer patients was 26.4±1.4, which was almost equal to that of the pulmonary group including the chronic obstructive pulmonary diseases, and significantly higher than that of cardiac or non-cardiopulmonary group. The irradiated lung cancer patients with complications of pulmonary or cardiopulmonary diseases showed a significantly increased D index, compared with patients without complications. Distribution index of tumor-bearing lung (D_r/1 index) was significantly higher than that of non-tumor-bearing lung. The D_r/1 index of tumor-bearing lung of small cell carcinoma patients significantly increased, compared with that of adenocarcinoma patients, and significantly increased according to whether or not the primary tumor occupied the hilar region and degree of extension of tumor invasion especially in the hilum as well as the mediastinum. In the follow-up irradiated lung cancer patients, the D index and D_r/1 index of non-tumor-bearing lung post-radiotherapy significantly increased, compared with pre-radiotherapy.
Conclusions: It is considered that the distribution index quantifying nonuniform distibution in the SPECT enables evaluation of the degree of impairment of lung as a whole, tumor-bearing lung, and non-tumorbearing lung in lung cancer patients, and results in presenting a useful indicator for radiotherapeutic planning and following up respiratory function after radiotherapy.

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Purpose: The objective was to assess the feasibility, toxicity, and efficacy of palliative intraluminal brachytherapy (ILBT) for recurrent esophageal cancer after definitive radiotherapy.
Method: From January 2000 to December 2002, 10 consecutive patients with recurrent esophageal cancer after definitive radiotherapy completed allocated ILBT, were enrolled into the analysis. All patients presented with a WHO dysphagia score III or more (III: 7; IV: 3). The ILBT was delivered with a special assembled applicator composed of three layers of plastic tubes, inserted transorally. The active treatment length of ILBT was defined as the site of recurrent esophageal tumor plus 1 cm each from the proximal and distal margins. The ILBT was performed by high-dose-rate iridium-192 remote after-loading technique. The ILBT consisted of 2 to 4 fractions of 3 Gy at 1-week intervals. The prescribed dose was specified at a 1 cm depth from the mid-dwell position and the dosimetry was calculated using computer-based software. Patients were followed up monthly and assessed for relief of dysphagia and development of complications.
Result: All patients completed the allocated ILBT schedule. Eight patients died (2 from distant metastasis; 3 from respiratory failure by tumor invasion; 2 from aspiration pneumonia; 1 from chemotherapy-induced sepsis). The median survival of the 10 patients was 5 months (range 2 to 32), and the estimated 1-year actuarial survival was 24%. Time to recurrence of more than 3 months was the only prognostic factor for longer survival (p=0.01). When the response of ILBT was assessed one month after treatment, eight patients achieved improvement of dysphagia, while two patients got worse. The median dysphagia progression-free interval (DPFI) of the 8 responders was 3 months (range 2 to 7). The predictive parameter for good ILBT response was an initial dysphagia score (p=0.01). Only one patient developed tracheo-esophageal fistula 3 months after ILBT
Conclusion: Fractionated ILBT is a feasible method of palliation for recurrent esophageal cancer after definitive radiotherapy. Prescribed dose with 9-12 Gy in three to four fractions weekly is well tolerated

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Radiotherapy following excision for keloids has shown to decrease the recurrence rate. But until now, no literature has reported the optimal dose of postoperative radiotherapy for keloids. We investigated the optimal dose of postoperative radiotherapy for keloids following excision.
Between July 2000 and March 2003, 21 patients with 29 keloid sites were treated with excision, sutured, and postoperative irradiation with a 4 MeV electron beam. The total dose were 12 Gy per 3 fractions. The results were evaluated at 6-38 months (Ave. 18 months) after treatment.
The effectiveness rate of total sites was 79%. The effectiveness rate was 43% in sites with highly stretched tension such as the chest wall, shoulder, abdominal wall and fingers and 91% in sites without highly stretched tension such as earlobes. As the results of analyzing therapeutic outcomes, the effeciveness rate in sites without highly stretched tension were significantly higher than those with highly stretched tension (p=0.0062). Our study suggested that the optimal dose of postoperative radiotherapy was 12 Gy or less for keloids in sites without highly stretched tension, much as the earlobe.

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Angioblastoma, that was first reported by Nakagawa in 1949, is a rare vascular tumor that usually appears in early childhood. It is seen as an erythematous patch to a reddish-brown area, that is frequentlyan indurated plaque with tenderness and usually occurs on the trunk or thigh. We report a case: a 5-month-old girl with angioblastoma on the temple, which showed a good response after 6-Gy irradiation. Low dose electron beam irradiation with 6-10Gy may be an effective method for management, if other treatments have a high morbidity rate or result in a poor outcome.

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Purpose: To evaluate, at our facility, the effects of incorrect placement of portal films on treatment field verification and the slant angles of portal film acquisition.
Methods and Materials: Geometric differences (pseudo-setup errors) between the correctly placed portal films (in which the film plane is perpendicular to the x-ray beam axis) and the incorrectly placed portal films (the film plane is not perpendicular to the x-ray beam axis) were mathematically calculated. Thirty-four portal films (25 patients) were analyzed in this study. These portal films were grouped into 2 categories according to the gantry angle: (1) the orthogonal group (i.e. treatment beam angles are of 0°, 90°, 180 and 270°), and (2) the oblique group (other beam angles). The slant angles of each group were evaluated.
Results: Mathematical calculations showed that pseudo-setup errors increased with an increase of the slant angle of the portal film and increased distance between the field-edge and an anatomical reference point. The mean slant angles of portal film acquisition for the orthogonal group and the oblique group were 3.4° (max=12.3°) and 6.0° (max=24.5°), respectively.
Conclusion: To minimize pseudo-setup errors associated with incorrect placement of portal films, an anatomical marker nearest to the field edge should be selected as the reference point for treatment field verification. However, the best way to completely eliminate the pseudo-setup errors is for film plane to be perpendicular to the x-ray beam axis.

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