Dosimetric Effect on Selectable Optimization Parameters of Volumatric Modulated Arc Therapy / 의학물리

The aim of this study is to evaluate plan quality and dose accuracy for Volumetric Modulated Arc Therapy (VMAT) on the TG-119 and is to investigate the effects on variation of the selectable optimization parameters of VMAT. VMAT treatment planning was implemented on a Varian iX linear accelerator with ARIA record and verify system (Varian Mecical System Palo Alto, CA) and Oncentra MasterPlan treatment planning system (Nucletron BV, Veenendaal, Netherlands). Plan quality and dosimetric accuracy were evaluated by effect of varying a number of arc, gantry spacing and delivery time for the test geometries provided in TG-119. Plan quality for the target and OAR was evaluated by the mean value and the standard deviation of the Dose Volume Histograms (DVHs). The ionization chamber and Delta4PT bi-planar diode array were used for the dose evaluation. For treatment planning evaluation, all structure sets closed to the goals in the case of single arc, except for the C-shape (hard), and all structure sets achieved the goals in the case of dual arc, except for C-shape (hard). For the variation of a number of arc, the simple structure such as a prostate did not have the difference between single arc and dual arc, whereas the complex structure such as a head and neck showed a superior result in the case of dual arc. The dose distribution with gantry spacing of 4degrees was shown better plan quality than the gantry spacing of 6degrees, but was similar results compared with gantry spacing of 2degrees. For the verification of dose accuracy with single arc and dual arc, the mean value of a relative error between measured and calculated value were within 3% and 4% for point dose and confidence limit values, respectively. For the verification on dose accuracy with the gantry intervals of 2degrees, 4degrees and 6degrees, the mean values of relative error were within 3% and 5% for point dose and confidence limit values, respectively. In the verification of dose distribution with Delta4PT bi-planar diode array, gamma passing rate was 98.72+/-1.52% and 98.3+/-1.5% for single arc and dual arc, respectively. The confidence limit values were within 4%. The smaller the gantry spacing, the more accuracy results were shown. In this study, we performed the VMAT QA based on TG-119 procedure, and demonstrated that all structure sets were satisfied with acceptance criteria. And also, the results for the selective optimization variables informed the importance of selection for the suitable variables according to the clinical cases.

A Retrospective Study of the Radiotherapy Care Patterns for Patients with Laryngeal Cancer and Comparison of Different Korean Hospitals Treated from 1998 through 1999 / 대한방사선종양학회지

PURPOSE: To investigate the care patterns for radiation therapy and to determine inter-hospital differences for patients with laryngeal carcinoma in Korea. MATERIALS AND METHODS: A total of 237 cases of laryngeal carcinoma (glottis, 144; supraglottis, 93) assembled from 23 hospitals, who underwent irradiation in the year of 1998 and 1999, were retrospectively analyzed to investigate inter-hospital differences with respect to radiotherapy treatment. We grouped the 23 hospitals based on the number of new patients annually irradiated in 1998; and designated them as group A (> or =900 patients), group B (> or =400 patients and <900 patients), and group C (<400 patients). RESULTS: The median age of the 237 patients was 62 years (range, 25 to 88 years), of which 216 were male and 21 were female. The clinical stages were distributed as follows: for glottis cancer, I; 61.8%, II; 21.5%, III; 4.2%, IVa; 11.1%, IVb; 1.4%, and in supraglottic cancer, I; 4.3%, II; 19.4%, III; 28.0%, IVa; 43.0%, IVb; 5.4%, respectively. Some differences were observed among the 3 groups with respect to the dose calculation method, radiation energy, field arrangement, and use of an immobilization device. No significant difference among 3 hospital groups was observed with respect to treatment modality, irradiation volume, and median total dose delivered to the primary site. CONCLUSION: This study revealed that radiotherapy process and patterns of care are relatively uniform in laryngeal cancer patients in Korean hospitals, and we hope this nationwide data can be used as a basis for the standardization of radiotherapy for the treatment of laryngeal cancer.

Preliminary Report of the 1998~1999 Patterns of Care Study of Radiation Therapy for Esophageal Cancer in Korea / 대한방사선종양학회지

PURPOSE: For the first time, a nationwide survey in the Republic of Korea was conducted to determine the basic parameters for the treatment of esophageal cancer and to offer a solid cooperative system for the Korean Pattern of Care Study database. MATERIALS AND METHODS: During 1998~1999, biopsy-confirmed 246 esophageal cancer patients that received radiotherapy were enrolled from 23 different institutions in South Korea. Random sampling was based on power allocation method. Patient parameters and specific information regarding tumor characteristics and treatment methods were collected and registered through the web based PCS system. The data was analyzed by the use of the Chi-squared test. RESULTS: The median age of the collected patients was 62 years. The male to female ratio was about 91 to 9 with an absolute male predominance. The performance status ranged from ECOG 0 to 1 in 82.5% of the patients. Diagnostic procedures included an esophagogram (228 patients, 92.7%), endoscopy (226 patients, 91.9%), and a chest CT scan (238 patients, 96.7%). Squamous cell carcinoma was diagnosed in 96.3% of the patients; mid-thoracic esophageal cancer was most prevalent (110 patients, 44.7%) and 135 patients presented with clinical stage III disease. Fifty seven patients received radiotherapy alone and 37 patients received surgery with adjuvant postoperative radiotherapy. Half of the patients (123 patients) received chemotherapy together with RT and 70 patients (56.9%) received it as concurrent chemoradiotherapy. The most frequently used chemotherapeutic agent was a combination of cisplatin and 5-FU. Most patients received radiotherapy either with 6 MV (116 patients, 47.2%) or with 10 MV photons (87 patients, 35.4%). Radiotherapy was delivered through a conventional AP-PA field for 206 patients (83.7%) without using a CT plan and the median delivered dose was 3,600 cGy. The median total dose of postoperative radiotherapy was 5,040 cGy while for the non-operative patients the median total dose was 5,970 cGy. Thirty-four patients received intraluminal brachytherapy with high dose rate Iridium-192. Brachytherapy was delivered with a median dose of 300 cGy in each fraction and was typically delivered 3~4 times. The most frequently encountered complication during the radiotherapy treatment was esophagitis in 155 patients (63.0%). CONCLUSION: For the evaluation and treatment of esophageal cancer patients at radiation facilities in Korea, this study will provide guidelines and benchmark data for the solid cooperative systems of the Korean PCS. Although some differences were noted between institutions, there was no major difference in the treatment modalities and RT techniques.

Postoperative Radiotherapy in the Rectal Cancers Patterns of Care Study for the Years of 1998~1999 / 대한방사선종양학회지

PURPOSE: To conduct a nationwide survey on the principles in radiotherapy for rectal cancer, and produce a database of Korean Patterns of Care Study. MATERIASL AND METHODS: We developed web-based Patterns of Care Study system and a national survey was conducted using random sampling based on power allocation methods. Eligible patients were who had postoperative radiotherapy for rectal cancer without gross residual tumor after surgical resection and without previous history of other cancer and radiotherapy to pelvis. Data of patients were inputted to the web based PCS system by each investigators in 19 institutions. RESULTS: Informations on 309 patients with rectal cancer who received radiotherapy between 1998 and 1999 were collected. Male to female ratio was 59 : 41, and the most common location of tumor was lower rectum (46%). Preoperative CEA was checked in 79% of cases and its value was higher than 6 ng/ml in 32%. Pathologic stage were I in 1.6%, II in 32%, III in 63%, and IV in 1.6%. Low anterior resection was the most common type of surgery and complete resection was performed in 95% of cases. Distal resection margin was less than 2 cm in 30%, and number of lymph node dissected was less than 12 in 31%. Chemotherapy was performed in 91% and most common regimen was 5-FU and leucovorine (69%). The most common type of field arrangement used for the initial pelvic field was the four field box (Posterior-Right-Left) technique (65.0%), and there was no AP-PA parallel opposing field used. Patient position was prone in 81.2%, and the boost field was used in 61.8%. To displace bowel outward, pressure modulating devices or bladder filling was used in 40.1%. Radiation dose was prescribed to isocenter in 45.3% and to isodose line in 123 cases (39.8%). Percent delivered dose over 90% was achieved in 92.9%. CONCLUSION: We could find the Patterns of Care for the radiotherapy in Korean rectal cancer patients was similar to that of US national survey. The type of surgery and the regimen of chemotherapy were variable according to institutions and the variations of radiation dose and field arrangement were within acceptable range.

Feasibility of Concurrent Adjuvant Chemotherapy and Radiotherapy after Breast-conserving Surgery in Early Breast Cancer / 한국유방암학회지

PURPOSE: The optimal sequence of chemotherapy (CT) and radiotherapy (RT) remains uncertain although both can reduce breast cancer recurrence after breast-conserving surgery (BCS). The current study was performed to evaluate whether concurrent RT with CT increases chemotherapy-associated toxicities. METHODS: Two hundred and thirty-eight patients with stage I and II breast cancers were prospectively allocated concurrent CT and RT (N=133) or sequential CT and RT (N= 105) after BCS. In the sequential group, the RT was started after completion of 3 cycles of CT with an additional 3 cycles of CT delivered after the RT. All patients underwent intravenous CMF chemotherapy composed of cyclophosphamide (500 mg/m2), methotrexate (50 mg/m2) and 5-FU (500 mg/ m2), every 3 weeks for 6 cycles following surgery. RESULTS: There were no significant differences between the two groups with regard to the grade 3 or 4 hematologic toxicities during chemotherapy or in abnormal liver enzyme elevation. Radiation related adverse effects, such as moist desquamation and pneumonitis symptom, were no different between the two groups. During the median 42 month follow-up period, range 16- to 60 months, 18 (13.5%) and 20 (19.1%) patients in the concurrent and sequential groups had systemic recurrences of breast cancer. The disease-free survival and local recurrence rates were no different between the two groups. CONCLUSION: Concurrent CT and RT were not associated with an increased toxicity and reasonable cosmetic results were achieved in this current study. The current study indicates that concurrent RT with CT after BCS is a feasible treatment modality, with the advantage of a shortening treatment time.

Survey on Radiotherpy Protocols for the Rectal Cancers among the Korean Radiation Oncologists in 2002 for the Development of the Patterns of Care Study of Radiation Therapy / 대한방사선종양학회지

PURPOSE: To conduct a nationwide survery on the principles in radiotherapy for rectal cancer, and develop the framework of a database of Korean Patterns of Care Study. MATERIALS AND METHODS: A consensus committee was established to develop a tool for measuring the patterns in radiotherapy protocols for rectal cancer. The panel was composed of radiation oncologists from 18 hospitals in Seoul Metropolitan area. The committee developed a survey format to analyze radiation oncologist's treatment principles for rectal cancer. The survey items developed for measuring the treatment principles were composed of 1) 8 eligibility criteria, 2) 20 items for staging work-ups and prognostic factors, 3) 7 items for principles of combined surgery and chemotherapy, 4) 9 patient set-ups, 5) 19 determining radiation fields, 6) 5 radiotherapy treatment plans, 7) 4 physical/laboratory examination to monitor a patient's condition during treatment, and 8) 10 follow-up evaluations. These items were sent to radiation oncologists in charge of gastrointestinal malignancies in all hospitals (48 hospitals) in Korea to which 30 replies were received (63%). RESULTS: Most of the survey items were replied to without no major differences between the repliers, but with the following items only 50% of repliers were in agreement:1) indications of preoperative radiation, 2) use of endorectal ultrasound, CT scan, and bone scan for staging work-ups, 3) principles of combining chemotherapy with radiotherapy, 4) use of contrast material for small bowel delineation during simulation, 5) determination of field margins, and 6) use of CEA and colonoscopy for follow-up evaluations. CONCLUSION: The items where considerable disagreement was shown among the radiation oncologists seemed to make no serious difference in the treatment outcome, but a practical and reasonable consensus should be reached by the committee, with logical processes of agreement. These items can be used for a basic database for the Patterns of Care Study, which will survey the practical radiotherapy patterns for rectal cancer in Korea.

The Clinical Significance of Follow Up SCC Levels in Patients with Recurrent Squamous Cell Carcinoma of the Cervix / 대한방사선종양학회지

PURPOSE: To investigate the clinical usefulness of a follow-up examination using serum squamous cell carcinoma antigen (SCC) for the early detection of recurrence in patients treated for cervical squamous cell carcinoma. MATERIALS AND METHODS: 20 patients who were treated for recurrent cervical squamous cell carcinoma between 1997 and 1998, who had experienced a complete remission after radiotherapy and who underwent an SCC test around the time when recurrence was detected, were included in this study. The levels of SCC were measured from the serum of the patients by immunoassay and values less than 2 ng/mL were regarded as normal. The sensitivity of the SCC test for use in the detection of recurrence, the association between the SCC values and the recurrence patterns and the tumor size and stage, and the temporal relation between the SCC increment and recurrence detection were evaluated. RESULTS: The SCC values were above normal in 17 out of 20 patients, so the sensitivity of the SCC test for the detection of recurrence was 85%, and the mean and median of the SCC values were 15.2 and 9.5 ng/mL, respectively. No differences were observed in the SCC values according to the recurrence sites. For 11 patients, the SCC values were measured over a period of 6 months before recurrence was detected, and the mean and median values were 13.6 and 3.6 ng/mL, respectively. The SCC values of 7 patients were higher than the normal range, and the SCC values of the other 4 patients were normal but 3 among them were above 1.5 ng/mL. At the time of diagnosis, the SCC valuess were measured for 16 of the 20 recurrent patients, and the SCC values of the patients with a bulky tumor (> or =4 cm) or who were in stage IIb or III were higher than those of the patients with a non-bulky tumor or who were in stage Ib or IIa. CONCLUSION: The SCC test is thought to be useful for the early detection of recurrence during the follow up period in patients treated for cervical squamous cell carcinoma. When an effective salvage treatment is developed in the future, the benefit of this follow-up SCC test will be increased.

Failure Pattern of Pineal and Ectopic Pineal Germ Cell Tumor after Gamma Knife Radiosurgery / 대한방사선종양학회지

PURPOSE: This study was performed to determine the optimal treatment volume of patients treating with radiation therapy for intracranial germ cell tumor. MATERIALS AND METHODS: From 1993 to 1998, 19 patients with intracranial germ cell tumors treated by gamma knife radiosurgery were analyzed. The location of tumor was as follows; 9 cases on pineal region, 1 case on suprasellar region, and 9 cases of multiple lesion. 7 patients were pathologically verified; 5 cases of germ cell tumor and 2 cases of non germinomatous germ cell tumor. Tumor volume was ranged from 2.4 cm3 to 74 cm3. Irradiation dose was 10 Gy to 20 Gy with 50% isodose curve. Follow up period was 10 months to 54 months. RESULTS: Recurrences were observed in 14 cases among 19 (74%) patients. Complete remission and partial remission were achieved in 2 (11%) and 10 (53%) respectively. No response was observed in 7 (36 %). 2 cases were recurred within original tumor bed. 6 cases were recurred beyond but contiguous with tumor bed. Ventricular relapses separated from pretreatment tumor bed were 3. Spinal recurrences were 4. Among 8 recurred cases of which tumor volume is smaller than 20 cm3, 2 were recurred within original tumor bed, 4 were recurred beyond but contiguous with tumor bed, and 1 spinal recurrence. Meanwhile, 6 cases of which tumor volume larger than 20 cm3, 1 case was recurred beyond but contiguous with tumor bed, 2 ventricular recurrences separated with original tumor bed, and 3 spinal recurrences. 5 cases which did not show any recurrence sign showed characteristics of single lesion, tumor volume smaller than 20 cm3 and normal tumor marker. All of 4 cases of spinal recurrences happened in the case having ventricular invasion or lesion. Among 9 cases having multiple lesion, only 3 cases recurred within original tumor bed or around tumor bed, the other 6 cases recurred separated from pretreatment tumor bed. CONCLUSION: Gamma knife radiosurgery is not recommended for the treatment of intracranial germ cell tumor. It is because of small treatment volume and inadequate radiation dose that are characteristics of gamma knife radiosurgery. Tumor volume, ventricular invasion or ventricular lesion in multiple lesion are important factors to be considered for the wide field radiation therapy. Tumor volume smaller than 20 cm3, single lesion, no ventricular lesion or invasion, and normal tumor marker are ideal indications for small involved field radiation therapy. Prophylactic spinal irradiation seems to be necessary when there is ventricular lesion, ventricular invasion, and multiple lesions. When the tumor volume is larger than 20 cm3, multiple lesions, abnormal tumor marker, and whole ventricular irradiation or partial brain irradiation would be possible and neoadjuvant chemotherapy would be most beneficial in these group.

The Efficacy of Induction Chemotherapy in Stage lll Non-Small Cell Lung Cancer / 대한방사선종양학회지

PURPOSE: This study was performed to analyze the efficacy of induction chemotherapy followed by radiation therapy in locally advanced non-small cell lung cancer. MATERIALS AND METHODS: Eighty patients with locally advanced non-small cell lung cancer treated from 1989 to 1995 at Pusan Paik hospital were analyzed retrospectively. Twenty-one patients were treated with induction chemotherapy followed by radiation therapy and Fifty-nine patients were treated with radiation therapy alone. Chemotherapy regimen consisted of cisplatin-based combination (2 or 3 drugs). All patients were treated by Co-60 or 6 MV linear accelerators. Radiation dose ranged from 50 Gy to 80 Gy (median, 64.8 Gy). We evaluated response rate, survival rate, and pattern of failure in both treatment groups. RESULTS: Overall response rate in induction chemotherapy group and radiotherapy alone group were 48% and 45%, respectively. Of the 80 patients, 46 patients were evaluable for pattern of failure. Initial failure pattern in induction chemotherapy group was as follows: 8 (67%) at locoregional, 4 (33) in distant metastasis. Radiation alone group was 21 (71%) and 5 (29%), respectively. Results showed no difference of distant failure between induction chemotherapy group and radiation alone group. The 1 and 2 year survival rate in induction chemotherapy group were 43% and 14%, respectively and in radiotherapy alone group, 31% and 7%, respectively (p=0.135). CONCLUSION: In stage lll non-small cell lung cancer, induction chemotherapy and radiation therapy showed increased tendency in survival with no statistical significance. Induction chemotherapy seems to have no effect of decreasing distant failure and no survival advantage compared with radiotherapy alone.

Evaluation of Tissue Inhomogeneity for Gamma-knife Radiosurgery Using Film Dosimetry / 대한방사선종양학회지

PURPOSE: Since the mid cranial fossa is composed of various thickness of bone, the tissue inhomogeneity caused by bone would produce dose attenuation in cobalt-60 gamma knife irradiation. The correction factor for bone attenuation of cobalt-60 which is used for gamma knife source is -3.5%. More importantly, nearly all the radiosurgery treatment planning systems assume a treatment volume of unit density; any perturbation due to tissue inhomogeneity is neglected. This study was performed to confirm the bone attenuation in mid cranial fossa using gamma knife. MATERIALS AND METHODS: Computed tomography was performed after Leksell stereotactic frame had been fixed to the Alderson Rando phantom (human phantom) skull area. Kodak X-omat V film was inserted into two sites of pituitary adenoma point and acoustic neurinoma point, and irradiated by gamma knife with 14mm and 18mm collimator. An automatic scanning densitometer with a 1mm aperture is used to measure the dose profile along the x and y axis. RESULTS: Isodose curve constriction in mid cranial fossa is observed with various ranges. Pituitary tumor point is greater than acoustic neurinoma point (0.2-3.0 mm vs. 0.1-1.3 mm) and generally 14 mm collimator is greater than 18mm collimator (0.4-3.0 mm vs. 0.2-2.2 mm). Even though the isodose constriction is found, constriction of 50% isodose curve which is used for treatment reference line does not exceed 1 mm. This range is too small to influence the treatment planning and treatment results. CONCLUSION: Radiosurgery planning system of gamma knife does not show significant error to be corrected without consideration of bone attenuation.

Survival and Complication Rate of Radiation Therapy in Stage I and II Carcinoma of uterine Cervix / 대한치료방사선과학회지

PURPOSE: To analyze survival rate and late rectal and bladder complication for patients with stage with stage I and II carcinoma of uterine cervix treated by radiation alone or combined with chemotherapy. MATERIALS AND METHODS: Between November 1984 and December 1993, 127 patients with stage I and II carcinoma of uterine cervix treated by radiation alone or combined therapy of radiation and chemotherapy. Retrospective analysis for survival rate was carried out on eligible 107 patients and review for complication was possible in 91 patients. The median follow-up was 47 months (range 3-118) and the median age of patients was 56 years (range 31-76). 26 patients were stage IB by FIGO classification. 40 were stage IIA and 41 were stage IIB. 86 cases were treated by radiation alone and 21 were treated by radiation and chemotherapy. 101 patients were treated with intracavitary radiation therapy (ICRT), of these, 80 were received low dose rate (LDR) ICRT and 21 were received high dose rate (HDR) ICRT. Of the patients who received LDR ICRT, 63 were treated by 1 intracavitary insertion and 17 were underwent 2 insertions. And we evaluated the external radiation dose and midline shield. RESULTS: Acturial survival rate at 5 years was 92% for stage IB, 75% for stage IIA, 53% for stage IIB and 69% in all patients. Grade 1 rectal complications were developed in 20 cases(22%), grade 2 were in 22 cases (24%), 22 cases (24%) of grade 1 urineary complications and 17 cases (19%) of grade 2 urinary complications were observed But no patients had severe complications that needed surgical management or admission care. Maximum bladder dose for the group of patients with urinary complications was higher than that for the patients without urinary complications(7608cGy v 6960cGy, p<0.01). Maximum rectal dose for the group of patients with rectal complications was higher than that for the patients without urinary complications (7041cGy v 6269cGy, p<0.01). While there was no significant difference for survival rate or bladder complication incidence as a function of dose to whole pelvis, Grade 2 rectal complication incidence was significantly lower for the patients receiving less than 4500cGy(6.3% v 25.5%, p<0.05). There was no significant difference between HDR ICRT group and LDR ICRT group for survival rate according to stage, on the other hand complication incidence was higher in the HDR group than LDR group. This was maybe due to different prescription doses between HDR group and LDR group. Midline shield neither improved survival rate nor deceased complication rate. The number of insertion in LDR ICRT group did not affect on survival and complication rate. CONCLUSION: In stage I and II carcinoma of uterine cervix, there was no significant difference for 5 year survival rate by radiation therapy technique. Rectal complication incidence was as a function of dose to whole pelvis and there were positive correlations of maximum dose of rectum and bladder and each complication incidence. So we recommand whole pelvis dose less than 4500cGy and maximum dose of rectum and bladder as low as possible.

Radiotherapy of Pineal and Ectopic Pineal Tumors / 대한치료방사선과학회지

From December 1984 to February 1990, 16 patients with tumors of pineal and suprasellar location were treated with radiation therapy. Tissue diagnoses were obtained before radiation therapy in 5 patients and 11 were irradiated without histologic confirmation. Initial treatments for these patients were craniospinal plus boost primary irradiation(six), whole brain plus boost primary irradiation(nine), primary tumor site irradiation(one). The 5 year actuarial survival rate is 71%. Three cases with elevated beta-human chorionic gonadotropin (HCG) responded favorably to radiation, but pineal tumors with elevated alpha-fetoprotein(AFP) did not respond well. Spinal metastasis developed in 2 cases (2/15) with elevated AFP : one received prophylactic spinal irradiation, another did not. Our studies suggest that more aggressive treatment would be necessary in patient with elevated AFP and in this patient, radiation therapy may be initiate without pathologic confirmation. From the result of our study, routine use of prophylactic spinal irrdiation for all patients with pineal region tumor is not indicated and use of prophylactic spinal irrdiation is considered for the patients with positive craniospinal fluid cytology, meningeal seeding, disease extension along the ventricular wall and biopsy proven germinoma

Radiotherapy of Uterine Cervical Cancer Using Fletcher-Suit-Delclos Cesium Applicator / 대한치료방사선과학회지

From Nov. 1983 through Feb. 1986, 35 patients of uterine cervical cancer were treated by external radiation therapy and intracavitary radiation therapy using Fletcher-Sult-Delclos applicator. Age of the patients ranged from 32 to 70 years (median age:53 years). All patients had follow up from 9 to 34 months and median follow up of 20 months. 4 patients were in stage I, 25 were in stage II, 5 were in stage III and I was in stage IV. Overall regression rate was 80% and uncorrected actuarial 2 year survival rate was 88%. The incindence of rectal complications were analyzed. There was no rectal complication in the patients who received less than 7000 rad maximal rectal dose, but 2 out of 17 patients who received more than 7000rad developed moderate degree (grade 2) of rectal complication. In viewing of our results, Fletcher-Suit-Delclos applicator (3M) seemed to be an appropriate instrument for intracavitary radiation therapy in the patients of uterine cervical cancer.