Dose comparison between prescription methods according to anatomical variations in intracavitary brachytherapy for cervical cancer

PURPOSE: We compared how doses delivered via two-dimensional (2D) intracavitary brachytherapy (ICBT) and three-dimensional (3D) ICBT varied anatomically. MATERIALS AND METHODS: A total of 50 patients who received 30 Gy of 3D ICBT after external radiotherapy (RT) were enrolled. We compared the doses of the actual 3D and 2D ICBT plans among patients grouped according to six anatomical variations: differences in a small-bowel V2Gy, small bowel circumference, the direction of bladder distension, bladder volume, sigmoid V3.5Gy, and sigmoid circumference. Seven dose parameters were measured in line with the EMBRACE recommendations. RESULTS: In terms of bladder volume, the bladder and small-bowel D2cc values were lower in the 150–250 mL bladder volume subgroup; and the rectum, sigmoid, and bladder D2mL values were all lower in the >250 mL subgroup, for 3D vs. 2D ICBT. In the sigmoid V3.5Gy >2 mL subgroup, the sigmoid and bladder D2mL values were significantly lower for 3D than 2D ICBT. The bladder D2mL value was also significantly lower for 3D ICBT, as reflected by the sigmoid circumference. In patients with a small bowel V2.0Gy >10 mL or small bowel circumference >15%, most dose parameters were significantly lower for 3D than 2D ICBT. The bladder distension direction did not significantly affect the doses. CONCLUSION: Compared to 2D ICBT, a greater bladder volume can reduce the internal 3D ICBT organ dose without affecting the target dose.

Clinical significance of the lymph node ratio in N1 breast cancer

PURPOSE: The purpose of this study was to evaluate the prognostic value of the lymph node ratio (LNR), which was defined as the proportion of involved nodes of all dissected nodes, in pN1 breast cancer. MATERIALS AND METHODS: We retrospectively analyzed the clinical data of patients with pN1 breast cancer (N = 144) treated at Keimyung University Dongsan Medical Center, Daegu, Korea between 2001 and 2010. The median age was 46 years (range, 27 to 66 years). The LNR was 0.01–0.15 (low LNR) in 130 patients and >0.15 (high LNR) in 14 patients. Sixty-five patients (45.1%) had T1 tumors, 74 (51.4%) had T2 tumors, and 5 (3.5%) had T3 tumors. Eighty-eight patients (61.1%) underwent total mastectomy and 56 (38.9%) underwent partial mastectomy. Fifty-nine patients (41.0%) underwent radiotherapy and 12 (8.3%) underwent regional radiotherapy. The median follow-up period was 65 months. RESULTS: The 5- and 10-year disease-free survival (DFS) rates were 92.7% and 82.4%, respectively. Univariate analyses revealed that high LNR (p = 0.004), total mastectomy (p = 0.006), no local radiotherapy (p = 0.036), and stage T2 or T3 (p = 0.010) were associated with worse DFS. In multivariable analysis, only high LNR (p = 0.015) was associated with worse DFS. CONCLUSION: High LNR is an independent prognostic factor in pN1 breast cancer and could be an indication for adjuvant radiotherapy in these patients.

Clinical significance of the lymph node ratio in N1 breast cancer

PURPOSE: The purpose of this study was to evaluate the prognostic value of the lymph node ratio (LNR), which was defined as the proportion of involved nodes of all dissected nodes, in pN1 breast cancer. MATERIALS AND METHODS: We retrospectively analyzed the clinical data of patients with pN1 breast cancer (N = 144) treated at Keimyung University Dongsan Medical Center, Daegu, Korea between 2001 and 2010. The median age was 46 years (range, 27 to 66 years). The LNR was 0.01–0.15 (low LNR) in 130 patients and >0.15 (high LNR) in 14 patients. Sixty-five patients (45.1%) had T1 tumors, 74 (51.4%) had T2 tumors, and 5 (3.5%) had T3 tumors. Eighty-eight patients (61.1%) underwent total mastectomy and 56 (38.9%) underwent partial mastectomy. Fifty-nine patients (41.0%) underwent radiotherapy and 12 (8.3%) underwent regional radiotherapy. The median follow-up period was 65 months. RESULTS: The 5- and 10-year disease-free survival (DFS) rates were 92.7% and 82.4%, respectively. Univariate analyses revealed that high LNR (p = 0.004), total mastectomy (p = 0.006), no local radiotherapy (p = 0.036), and stage T2 or T3 (p = 0.010) were associated with worse DFS. In multivariable analysis, only high LNR (p = 0.015) was associated with worse DFS. CONCLUSION: High LNR is an independent prognostic factor in pN1 breast cancer and could be an indication for adjuvant radiotherapy in these patients.

Long-term outcomes of surgery and radiotherapy for secreting and non-secreting pituitary adenoma

PURPOSE: To investigate treatment outcome and long term complication after surgery and radiotherapy (RT) for pituitary adenoma. MATERIALS AND METHODS: From 1990 to 2009, 73 patients with surgery and RT for pituitary adenoma were analyzed in this study. Median age was 51 years (range, 25 to 71 years). Median tumor size was 3 cm (range, 1 to 5 cm) with suprasellar (n = 21), cavernous sinus extension (n = 14) or both (n = 5). Hormone secreting tumor was diagnosed in 29 patients; 16 patients with prolactin, 12 patients with growth hormone, and 1 patient with adrenocorticotrophic hormone. Impairment of visual acuity or visual field was presented in 33 patients at first diagnosis. Most patients (n = 64) received RT as postoperative adjuvant setting. Median RT dose was 45 Gy (range, 45 to 59.4 Gy). RESULTS: Median follow-up duration was 8 years (range, 3 to 22 years). In secreting tumors, hormone normalization rate was 55% (16 of 29 patients). For 25 patients with evaluable visual field and visual acuity test, 21 patients (84%) showed improvement of visual disturbance after treatment. The 10-year tumor control rate for non-secreting and secreting adenoma was 100% and 58%, respectively (p < 0.001). Progression free survival rate at 10 years was 98%. Only 1 patient experienced endocrinological recurrence. Following surgery, 60% (n = 44) suffered from pituitary function deficit. Late complication associated with RT was only 1 patient, who developed cataract. CONCLUSION: Surgery and RT are very effective and safe in hormonal and tumor growth control for secreting and non-secreting pituitary adenoma.

Concurrent chemoradiotherapy improves survival outcome in muscle-invasive bladder cancer

PURPOSE: To evaluate survival rates and prognostic factors related to treatment outcomes after bladder preserving therapy including transurethral resection of bladder tumor, radiotherapy (RT) with or without concurrent chemotherapy in bladder cancer with a curative intent. MATERIALS AND METHODS: We retrospectively studied 50 bladder cancer patients treated with bladder-preserving therapy at Keimyung University Dongsan Medical Center from January 1999 to December 2010. Age ranged from 46 to 89 years (median, 71.5 years). Bladder cancer was the American Joint Committee on Cancer (AJCC) stage II, III, and IV in 9, 27, and 14 patients, respectively. Thirty patients were treated with concurrent chemoradiotherapy (CCRT) and 20 patients with RT alone. Nine patients received chemotherapy prior to CCRT or RT alone. Radiation was delivered with a four-field box technique (median, 63 Gy; range, 48.6 to 70.2 Gy). The follow-up periods ranged from 2 to 169 months (median, 34 months). RESULTS: Thirty patients (60%) showed complete response and 13 (26%) a partial response. All patients could have their own bladder preserved. Five-year overall survival (OS) rate was 37.2%, and the 5-year disease-free survival (DFS) rate was 30.2%. In multivariate analysis, tumor grade and CCRT were statistically significant in OS. CONCLUSION: Tumor grade was a significant prognostic factor related to OS. CCRT is also considered to improve survival outcomes. Further multi-institutional studies are needed to elucidate the impact of RT in bladder cancer.

Is Prophylactic Irradiation to Para-aortic Lymph Nodes in Locally Advanced Cervical Cancer Necessary? / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study evaluated the efficacy of extended field irradiation (EFI) in patients with locally advanced cervical cancer without para-aortic nodal involvement. MATERIALS AND METHODS: A total of 203 patients with locally advanced cervical cancer (International Federation of Gynecology and Obstetrics [FIGO] stage, IB2-IIIB) treated with radiotherapy at Keimyung University Dongsan Medical Center from 1996 to 2010 were retrospectively analyzed. The median patient age was 59 years (range, 29 to 83 years). None of the patients had para-aortic node metastases. Of the 203 patients, 88 underwent EFI and 115 underwent irradiation of the pelvis only. Concurrent chemoradiotherapy (CCRT) was administered to 133 patients. EFI field was used for treatment of 26 patients who received radiotherapy alone and 62 who received CCRT. RESULTS: The median follow-up period was 60 months. The 2- and 5-year overall survival (OS) rates were 87.8% and 73.5%, respectively, and the 2- and 5-year disease-free survival rates were 81.7% and 75.0%, respectively, however, no survival differences were observed between the two treatment field groups. EFI tended to increase OS in the radiotherapy alone group, but not in the CCRT group. CONCLUSION: These findings suggest that EFI does not have a significant effect in patients with locally advanced cervical cancer, especially in patients receiving CCRT. Conduct of additional studies will be required in order to confirm these findings.

Practical Output Dosimetry with Undefined NdwCo-60 of Cylindrical Ionization Chamber for High Energy Photon Beams of Linear Accelerator / 의학물리

For the determination of absorbed dose to water from a linear accelerator photon beams, it needs a exposure calibration factor Nx or air kerma calibration factor Nk of air ionization chamber. We used the exposure calibration factor Nx to find the absorbed dose calibration factors of water in a reference source through the TG-21 and TRS-277 protocol. TG-21 used for determine the absorbed dose in accuracy, but it required complex calculations including the chamber dependent factors. The authors obtained the absorbed dose calibration factor NdwCo-60 for reduce the complex calculations with unknown Ndw only with Nx or Nk calibration factor in a TM31010 (S/N 1055, 1057) ionization chambers. The results showed the uncertainty of calculated Ndw of IC-15 which was known the Nx and Ndw is within -0.6% in TG-21, but 1.0% in TRS-277. and TM31010 was compared the Ndw of SSDL to that of PSDL as shown the 0.4%, -2.8% uncertainty, respectively. The authors experimented with good agreement the calculated Ndw is reliable for cross check the discrepancy of the calibration factor with unknown that of TM31010 and IC-15 chamber.

Interval between Surgery and Radiation Therapy Is an Important Prognostic Factor in Treatment of Rectal Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study is to evaluate survival and prognostic factors for rectal cancer, including interval between surgery and radiation therapy after surgery, radiation therapy, and chemotherapy. MATERIALS AND METHODS: We conducted a retrospective study of 153 patients with rectal cancer who were treated with surgery, radiotherapy with/without chemotherapy at Keimyung University Dongsan Medical Center from January, 1988 to December, 2005. The study included 89 males and 64 females, with a median age of 56 years (range, 23 to 81 years). Tumor, node and metastasis (TNM) was I in 23 patients, II in 39, and III in 91. Radiation therapy was performed on pelvic fields using a median dose of 54 Gy five days per week, 1.8 Gy once per day. Ninety two patients were treated with radiotherapy, 43 with concurrent chemo-radiation therapy and 18 with sequential therapy after surgery. The median follow-up period was 52 months (range, 4 to 272 months). The interval between surgery and radiation was 1-25 weeks (median, 5 weeks). RESULTS: Two-year and five-year overall survival rate was 64.7% and 46.4%, respectively. Two-year and five-year disease-free-survival (DFS) rate was 58.6% and 43.1%, respectively. Median DFS was 39 months. Loco-regional failure was evident in 10.5% of patients, 8.4% had distant metastasis, and 9.2% had both. In multivariate analysis, TNM stage and interval between surgery and radiation therapy (5 weeks; 95% confidence interval, 1.276 to 2.877; hazard ratio, 1.916; p=0.002) were significant prognostic factors of DFS. CONCLUSION: Survival rates for rectal cancer after surgery, chemotherapy, and radiation therapy were similar to those reported in previous studies. Starting radiation therapy as soon as possible after surgery, especially within the first five weeks after surgery, is suggested.

Radiation Therapy for Hepatocellular Carcinoma with Portal Vein Tumor Thrombosis / 대한방사선종양학회지

PURPOSE: To evaluate the effectiveness of radiation therapy (RT) for hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) and to analyze the prognostic factors. MATERIALS AND METHODS: From December 2004 to April 2009, 70 patients who had HCC with PVTT were treated with RT at Keimyung University Dongsan Medical Center. Nineteen patients whose total dose was below 30 Gy and one patient who underwent liver transplantation were excluded. The remaining 50 patients (45 males, 5 females; median age 55 years) were analyzed. According to the LCSGJ TNM stage, there were 27 patients (54.0%) with stage III and 23 (46.0%) with stage IV. Total dose of 30~54 Gy was administered (median 45). Thirty patients (60.0%) were treated with concurrent chemoradiation therapy (CCRT). The median follow-up duration was from 13.5 months (range, 3 to 70 months). RESULTS: The median survival time from the start of RT was 9 months. One-year and 2-year overall survival rates were 24.9% and 11.2%, respectively. At the follow-up time, three patients (6.0%) displayed no evidence of disease. Seven patients (14.0%) were alive with disease, and 40 (80.0%) patients had expired due to disease progression. CCRT was associated with worse survival than RT alone (p=0.034). Response to RT (p=0.037), CLIP stage (p=0.017), and TNM stage (p=0.041) were statistically significant prognostic factors. There was no radiation-induced liver disease. CONCLUSION: RT is an effective and safe modality for HCC with PVTT. Further studies such as prospective randomized trials are needed to confirm the role of RT for HCC with PVTT.

Development of Lead Free Shielding Material for Diagnostic Radiation Beams / 의학물리

The shielding materials designed for replacement of lead equivalent materials for lighter apron than that of lead in diagnostic photon beams. The absorption characteristics of elements were applied to investigate the lead free material for design the shielding materials through the 50 kVp to 110 kVp x-ray energy in interval of 20 kVp respectively. The idea focused to the effect of K-edge absorption of variable elements excluding the lead material for weight reduction. The designed shielding materials composited of Tin 34.1%, Antimon 33.8% and Iodine 26.8% and Polyisoprene 5.3% gram weight account for 84 percent of weight of lead equivalent of 0.5 mm thickness. The size of lead-free shielder was 200x200x1.5 mm3 and 3.2 g/cm3 of density which is equivalent to 0.42 mm of Pb. The lead equivalent of 0.5 mm thickness generally used for shielding apron of diagnostic X rays which is transmitted 0.1% for 50 kVp, 0.9% for 70 kVp and 3.2% for 90 kVp and 4.8% for 110 kVp in experimental measurements. The experiment of transmittance for lead-free shielder has showed 0.3% for 50 kVp, 0.6% for 70 kVp, 2.0% for 90 kVp and 4.2% for 110 kVp within 0.1%. respectively. Using the attenuation coefficient of experiments for 0.5 mm Pb equivalent of lead-free materials showed 0.1%. 0.3%, 1.0% and 2.4%, respectively. Furthermore, the transmittance of lead-free shielder for scatter rays has showed the 2.4% in operation energy of 50 kVp and 5.9% in energy of 110 kVp against 2.4% and 5.1% for standard lead thickness within 0.2% discrepancy, respectively. In this experiment shows the designed lead-free shielder is very effective for reduction the apron weight in diagnostic radiation fields.

Determination of Phantom Scatter Factors for Small Photon Fields / 의학물리

Total scatter factor (Scp), head scatter factor (Sc) and phantom scatter factor (Sp) are very important for accurate radiation therapy at stereotactic radiosurgery (SRS) with irregular field shape using micro-MLC and intensity modulated radiation therapy (IMRT) including many small field sizes. In this study we measured and compared Scp with reference ion chamber, pinpoint chamber and diode detector and adapted the resuls form diode detector. Head scatter factors for small field sizes were also measured with diode detector covered 1.5 cm-thick solid water build-up cap. Some errors like as electron contamination of 1~3% were included in the values of Sc but trend of total results of Sc was coincided with basic theory. Phantom scatter factors for small field sizes were calculated form Scp and Sc. The results of Sp were compared and were well-agreed with those of other authors.

Quality Correction for Ir-192 Gamma Rays in Air Kerma Strength Dosimetry Using Cylindrical Ionization Chambers / 의학물리

The quality correction in the air kerma dosimetry for Ir-192 using farmer type ionization chambers calibrated by Co-60 quality is required. In this study we determined quality factor (kappa u) of two ionization chambers of PTW-N30001 and N23333 for Ir-192 source using dosimetric method. The quality factors for energy spectrum of microSelectron were determined as kappa u=1.016 and 1.017 for PTW-N30001 and N23333 ionization chambers respectively. We applied quality factors in air kerma dosimetry for microSelectron source and compared with reference values. As a results we found that the differences between reference air kerma rate and measured it with and without quality correction were about -0.5% and -2.0% respectively.

Estimation of RTP Accuracy Based the International Reference Level / 의학물리

In this study, we have estimated error of calculation results for 6-type RTP systems and investigated a toleration for error of the RTPs referenced from the evaluation items of AAPM Report-62. For this study, we have introduced the concept of 'normal dose rate(NDR)' and compared the results of experiment and calculation from RTPs at the same reference level. The results from all RTPs were satisfied at various field shapes and heterogeneous phantom materials except the surface irregularity.

Accuracy Evaluation of Treatment Planning System Using Irregular-surface Water Phantom / 의학물리

We evaluated on the calculation accuracy of treatment planning system (TPS) with phantom having convex and concave surface. The TPS is Eclipse (Varian, USA) using both algorithms AAA and PBC for photon dose calculations. PBC algorithms have three corrections of Batho, modified Batho (M-Batho), and equivalent TAR (E-TAR). The field sizes were 10x10 cm2 and 20x20 cm2, and MLC-shaped fields for these fields. We measured doses at three depths 5, 10 and 15 cm in phantom of SSD=90 cm in the condition of inserted farmer chamber. For given conditions, we have calculated dose with these algorithms and compared them with measured doses. In AAA the calculated doses (dose/MU) were agreed to measured doses within +/-1% in flat and convex surface and were under estimated with -1.9% maximum in concave surface. In PBC the calculated doses were over estimated with +1.7% and +4.1% respectively in flat and convex surface and the differences were from -3.1% to +2.1% in concave surface. In comparison of criteria from AAPM and IAEA reports, and statistical analysis for these results, it is found that the AAA's results are in good agreement with measured values and the M-Batho's results are generally good agreed with measured values among PBC algorithms.

Effect of Transverse Magnetic Field on Dose Distribution of High Energy Electron Beam / 의학물리

In this work we have measured the dose distribution and the percent depth dose of 20 MeV electron beam using the X-OMAT films in order to verify the effects of transverse magnetic field on high energy elecrtron beam in a phantom. The result shows about 30% increase of the percent depth dose at 4.5 cm depth under the transverse magnetic field of 1.5 Tesla at 7.5 cm depth. We have verified that these were in an agreement with other theoretical results.

Monte Carlo Calculation on the Dose Modulation Using Dynamic Magnetic Fields for 10 MV X-rays / 의학물리

Monte Carlo calculations were performed to demonstrate the dose modulation with dynamic magnetic fields in phantom. The goal of this study is to obtain the uniform dose distributions at a depth region as a target on the central axis of photon beam under moving transverse magnetic field. We have calculated the depth dose curves for two cases of moving magnetic field along a depth line, constant speed and optimal speed. We introduced step-by-step shift and time factor of the position of the electromagnet as an approximations of continuous moving. The optimal time factors as a function of magnetic field position were calculated by least square methods using depth dose data for static magnetic field. We have verified that the flat depth dose is produced by varying the speed of magnetic field as a function of position as a results of Monte Carlo calculations. For 3 T magnetic field, the dose enhancement was 10.1% in comparison to without magnetic field at the center of the target.

The Modulation of Radiosensitivity by Combined Treatment of Selective COX-2 Inhibitor, NS 398 and EGF Receptor Blocker AG 1478 in HeLa Cell Line / 대한방사선종양학회지

PURPOSE: Selective inhibition of multiple molecular targets may improve the antitumor activity of radiation. Two specific inhibitors of selective cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) were combined with radiation on the HeLa cell line. To investigate cooperative mechanism with selective COX-2 inhibitor and EGFR blocker, in vitro experiments were done. MATERIASL AND METHODS: Antitumor effect was obtained by growth inhibition and apoptosis analysis by annexin V-Flous method. Radiation modulation effects were determined by the clonogenic cell survival assay. Surviving fractions at 2 Gy (SF2) and dose enhancement ratio at a surviving fraction of 0.25 were evaluated. To investigate the mechanism of the modulation of radiosensitivity, the cell cycle analyses were done by flow cytometry. The bcl-2 and bax expressions were analyzed by western blot. RESULTS: A cooperative effect were observed on the apoptosis of the HeLa cell line when combination of the two drugs, AG 1478 and NS 398 with radiation at the lowest doses, apoptosis of 22.70% compare with combination of the one drug with radiation, apoptosis of 8.49 %. In cell cycle analysis, accumulation of cell on G0/G1 phase and decrement of S phase fraction was observed from 24 hours to 72 hours after treatment with radiation, AG 1478 and NS 398. The combination of NS 398 and AG 1478 enhanced radiosensitivity in a concentration-dependent manner in HeLa cells with dose enhancement ratios of 3.00 and SF2 of 0.12 but the combination of one drug with radiation was not enhanced radiosensitivity with dose enhancement ratios of 1.12 and SF2 of 0.68 (p=0.005). The expression levels of bcl-2 and bax were reduced when combined with AG 1478 and NS 398. CONCLUSION: Our results indicate that the selective COX-2 inhibitor and EGFR blocker combined with radiation have potential additive or cooperative effects on radiation treatment and may act through various mechanisms including direct inhibition of tumor cell proliferation, suppression of tumor cell cycle progression and inhibition of anti-apoptotic proteins.

Voluntary Habitual Hip Dislocation in a child / 대한정형외과학회잡지

Voluntary habitual dislocation of the hip is very rarely reported in children, and only 13 cases have been reported in the literature. We add a new case in a 5 year old boy. The boy did not have previous history of trauma, skeletal and/or soft tissue anomalies, nor known connective disease. He was treated by intertrochanteric varusinward rotation osteotomy of the affected hip on February 25, 1985 and was followed until January 11, 1993. Postoperative convalescence was uneventfully successful, and the hip developed well without any obvious dysplasia at the latest follow-up.

High Lumbar Disc Herniation in Achondroplasia: A Case Report / 대한정형외과학회잡지

Fifty percents of patient with achondroplasia present neurological disturbances of varying degree. Congenital narrowing of the spinal canal in achondroplastics seems to be the main cause of the cord disturbance, and there are several other causes such as prolapse of intervertebral discs, spondyloarthitic degenerative manifestations and wedging of vertebral body. Surgical treatment of the cord disturbance consist of anterior decompression with fusion and posterior decompression. We experienced L1-2 disc herniation in achondroplasia with rapid progression of neurologic symptoms and treated with posterior decompression. Two years after operation, the patient had good result.