• The Korean Journal of Nuclear Medicine Technology
• /
• v.21 no.2
• /
• pp.74-79
• /
• 2017

Purpose Proton therapy can deliver an optimal dose to tumor while reducing unnecessary dose to normal tissue as compared the conventional photon therapy. As proton beams are irradiated into tissue, various positron emitters are produced via nuclear fragmentation reactions. These positron emitters could be used for the dose verification by using PET. However, the short half-life of the radioisotopes makes it hard to obtain the enough amounts of events. The aim of this study is to investigate the effect of off-line PET imaging scan time on the PET image quality. Materials and Methods The various diameters of spheres (D=37, 28, 22 mm) filled with distilled water were inserted in a 2001 IEC body phantom. Then proton beams (100 MU) were irradiated into the center of the each sphere using the wobbling technique with the gantry angle of $0^{\circ}$. The modulation widths of the spread out bragg peak were 16.4, 14.7 and 9.3 cm for the spheres of 37, 28 and 22 mm in diameters respectively. After 5 min of the proton irradiation, the PET images of the IEC body phantom were obtained for 50 min. The PET images with different time courses (0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min) were obtained by dividing the frame with a duration of 10 min. In order to evaluate the off-line PET image quality with the different time courses, the contrast-to-noise ratio (CNR) of the PET image calculated for each sphere. Results The CNRs of the sphere (D=37 mm) were 0.43, 0.42, 0.40, 0.31 and 0.21 for the time courses of 0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min respectively. The CNRs of the sphere (D=28 mm) were 0.36, 0.32, 0.27, 0.19 and 0.09 for the time courses of 0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min respectively. The CNR of 37 mm sphere was decreased rapidly after 30 min of the proton irradiation. In case of the spheres of 28 mm and 22 mm, the CNR was decreased drastically after 20 min of the irradiation. Conclusion The off-line PET imaging time is an important factor for the monitoring of the proton therapy. In case of the lesion diameter of 22 mm, the off-line PET image should be obtained within 25 min after the proton irradiation. When it comes to small size of tumor, the long PET imaging time will be beneficial for the proton therapy treatment monitoring.

• Radiation Oncology Journal
• /
• v.15 no.3
• /
• pp.243-249
• /
• 1997

Purpose : In radiation therapy, NTCF is very importart indicator of selecting the optimal treatment plan. In our study, we tried to find out usefullness of NTCP in lung cancer by comparng the incidence of radiation pneumonitis with NTCP. Materials and Methods : From August 1993 to December 1994, thirty six patients with locally advanced non=small cell lung cancer were treated by concurrent chemoradiation therapy. Total dose of radiation therapy was 6480cGy (120cGy, bid) and chemotherapeutlc agents were mitomycin C. vinblastion, cisplatin (2 cycles, 4 weeks interval). We evaluated the development of raniation pneumonitis by CT scan, chest x-rar and clinical symptoms. We used grading system of South Western Oncology Group (SWOG) for radiation pneumanitis. Dose Volume Histograms (DVH) were analyzed for ipsilateral and whole lung, Non uniform DVH was translated to uniform DVH by effective volume method. With these data, we calculated NTCP for ipsilateral and whole lung. Finally we compared the clinical results to NTCP. Results : Eight of thrity six patients developed radiation pneumonitis. Of these 8 patients , 6 had grade I severity and 2 had grade II. The average NTCP value cf the patients who showed radiation pneumonitis was significantly higher than that uf the patients without pneumonitis $(66\%\;vs.\;26.4\%)$. But the results of pulmonary function test was not correlated with NTCP. Conclusion : NTCP of lung is very good indicator for selecting rival treatment planning in lung cancer. According to the results of NTCP, it may be possible to adjust target volume and optimize target dose. In the near future, we are going to anaiyze the effect of hyperfractionation and concurrent chemotherapy in addition to NTCP.

• Radiation Oncology Journal
• /
• v.15 no.3
• /
• pp.225-231
• /
• 1997

Purpose : Radiation therapy in combination with surgery has an important role in the therapy of the head and neck cancer We conducted a prospective study for patients with head and neck cancer treated with surgery and radiation to evaluate the effect of therapies on the thyroid gland, and to identify the factors that might influence the development of hypothyroidism. Materials and Methods : From September 1986 through December 1994, 71 patients with head and cancer treated with surgery and radiation were included in this prospective study. Patients' age ranged from 32 to 73 years with a median age of 58 years. There were 12 women and 59 men. The primary tumor sites were larynx in 34 patients, hypopharynx in 13 patients, oral cavity in 12 patients, unknown primary of the neck in 6 patients, salivary gland in 3 patients, maxillary sinus in 2 patients, and oropharynx in 1 patient. Total laryngectomy with neck dissection was carried out in 45 patients and neck dissection alone in 26 patients. All patients were serially monitored for thyroid function (T3, T4, free T4, TSH, antithyroglobulin antibody and antimicrosomal antibody) before and after radiation therapy. Radiation dose to the thyroid gland ranged from 40.6Gy to 60Gy with a median dose of 50Gy The follow-up duration was 3 to 80 months. Results :The overall incidence of hypothyroidism was 56.3\%$);7 out of 71 patients $(9.9\%)$ developed clinical hypothyroidism and 33 patients $(46.4\%)$ developed subclinical hypothyroidism. No thyroid nodules, thyroid cancers, or hyperthyroidism was detected. Hypothyroidism developed earlier in patients who underwent total laryngectomy with neck dissection than in patients with neck dissection alone (P<0.05). The risk factor that significantly influenced the incidence of hypothyroidism was a combination of surgery (total laryngectomy with neck dissection) and radiation therapy (P=0.0000), Four of 26 patients $(15.4\%)$ with neck dissection alone developed hypothyroidism while 36 of 45 patients $(80\%)$ with laryngectomy and neck dissection developed hypothyroidism. Conclusion : The hypothyroidism following surgery and radiation therapy was a relatively common complication. The factor that significantly influenced theincidence of hypothyroidism was combination of surgery and radiation therapy. Evaluation of thyroid function before and after radiation therapy with periodic thyroid function tests is recommended for an early detection of hypothyroidism and thyroid hormone replacement therapy is recommended whenever hypothyroidism develops.

• Tuberculosis and Respiratory Diseases
• /
• v.49 no.3
• /
• pp.353-364
• /
• 2000

Background : Bronchoscopy is a useful diagnostic tool, for accurate localization of the bleeding site and the management of hemoptysis. However, there is some controversy about the optimal timing of bronchoscopy. Method : To determine the optimal timing of bronchoscopy in hemoptysis, we reviewed the medical records of 118 patients and analyzed the following relationships amongst simple chest PA findings, namely, the duration and amount of hemoptysis, and the timing of bronchoscopy retrospectively. Results : The major causes of hemoptysis were active tuberculosis(28.8%), inactive tuberculosis(10.2%), bronchiectasis(17.0%), lung cancer(7.6%), and aspergilloma(7.6%). Localization of the bleeding focus by bronchoscopy was possible in 87.5% (21/24 cases) during active bleeding, and it was possible in 40.4% after bleeding had stopped(p<0.05). The localization rate of bleeding focus was 59.8% when the chest PA showed certain abnormalities, but it decreased to 27.8% when the chest PA finding was normal(p<0.05). When chest PA showed diffuse abnormalities or its finding was normal, the localization rate of bleeding focus significantly increased if bronchoscopy was performed during bleeding or within 48 hours of the cessation of active bleeding. The localization rate was higher as the amount of hemoptysis became larger(p<0.05). The localization rate of early bronchoscopy(during bleeding or within 48 hours of the cessation of active bleeding) was significantly higher when the duration of hemoptysis was less than 1 week, but there was no advantage if the duration was 1 week or longer. Early bronchoscopy was also necessary to localize the bleeding focus for surgical resection in 4 patients, and the bronchoscopy itself was therapeutic in 1 patient whose bleeding was successfully managed with thrombin-application via bronchoscope. Conclusion : It is concluded that flexible bronchoscopy is useful at not only localizing the bleeding focus but also in preparing a therapeutic plan, and early bronchoscopy is more favorable in hemoptysis.

• Tuberculosis and Respiratory Diseases
• /
• v.49 no.4
• /
• pp.474-485
• /
• 2000

Background : Current studies on multimodal strategy for N2 non-small cell lung cancer are being high interest, have drawn much attention. N2 lung cancer, however, is composed of is divided into several sub groups with that have different prognoses. The prognostic factors still remain controversial. Methods : Between January 1990 and June 1999, 180 patients with N2 lung cancer who underwent surgical resection were investigated, excluding 10 of these for surgical mortality. All patients underwent mediastinal lymph node dissection. 20 clinicopathologic factors were investigated by univariable and multivariable analyses to identify significant prognostic factors among resected N2 disease. Results : The overall 5-year survival rate was 20.6%. Multivariable analyses among overall patients revealed 3 significant prognostic factors : Age, Histologic type, Vascular invasion. Based on the result, 49 patients with both age more than 60 and pathologic Non-squamous cell showed a 5-year survival of 5.0%, whereas 37 patients with neither of the factors showed a 5-year survival of 56.6%(p<0.001). And 12 patients with both vascular invasion and pathologic Non-squamous cell showed a 5-year survival of 11.9%, whereas 67 patients with neither of the factors showed a 5-year survival of 33.6%(p=0.01). Conclusion : The prognosis of surgically resected N2 disease varies according to the 3 significant prognosis factors. Tumor size may be an additional influencing factor in the prognosis of N2 disease.

• Tuberculosis and Respiratory Diseases
• /
• v.62 no.6
• /
• pp.506-515
• /
• 2007

Background: Nosocomial pneumonia in an intensive care unit (ICU) is associated with a high mortality rate. Diagnosing a respiratory tract infection in critically ill patients is still difficult but detailed information for the pathogens is needed to establish an adequate antimicrobial treatment. This study examined the causative organisms and their antimicrobial resistance using bronchoalveolar lavage (BAL) from patients suspected of having pneumonia in the ICU. Methods: From January 2004 to June 2006, ICU patients with diffuse lung infiltration were prospectively enrolled. The BAL was used to diagnose the respiratory infection, with 104 > or = organisms considered a positive result. The most common organisms and their antimicrobial resistances were analyzed from the quantitative BAL cultures in the burn ICU and non-burn ICU. Results: A total 72 patients were included, 35 (M 29, F 6) in the burn ICU and 37 (M 26, F 11) in the non-burn ICU. 27 patients (77.1%) in the burn ICU and 22 patients (59.5%) in the non-burn ICU met the criteria for a positive BAL culture. The major pathogens were Staphylococcus aureus, Acinetobacter species and Pseudomonas aeruginosa. All strains (100%) of Staphylococcus aureus isolated from BAL (9 cases) were methicillin-resistant (MRSA) in the burn ICU, but 5 strains (71.4%, 7 cases) were MRSA in the non-burn ICU. Regarding Pseudomonas aeruginosa, the rate of resistance to amikacin, ciprofloxacin, cefepime, imipenem, ceftazidime, piperacillin/tazobactam in the burn and non-burn ICU ranged from 45.5% to 90% and 25% to 50%, respectively. In addition, the rate of resistance of Acinetobacter species to the above drugs in the burn and non-burn ICU ranged from 81.8% to 100% and 62.5% to 100%, respectively. Conclusions: These results are expected to provide useful guidelines for choosing the effective empirical antimicrobial therapy in patients with lung infiltrations in the burn and non-burn ICU.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.3
• /
• pp.498-503
• /
• 2006

This in vitro study compared the remineralization of incipient interproximal caries in the presence of three glass ionomer cements (highly-filled glass ionomer cement, compomer, resin-modified glass ionomer cement) and a resin composite(control). The long-term changes in remineralization caused by each material were evaluated by microtomography. Proximal restoration was simulated by placing tooth specimens and the various glass ionomer cements in closed containers with artificial saliva at $37^{\circ}C$ and pH 7.0 for 30 days with constant circulation Tomographic images were obtained with a micro CT scanner at 90, 180, and 270 days, and density-measuring software was used to calculate the micro-density of artificial caries lesions in the specimens. The mean density changes were compared between groups in order to evaluate the effects of remineralization. All data were analyzed using one-way ANOVA and the post-HOC Tukey multiple comparison test at p<0.05. While the density of artificial caries lesions increased for all treatments, the increases for the three glass ionomer groups were significantly higher than that for the resin group in each three month period. As time went on, the amount of density increase of the glass ionomer groups decreased, and significant differences were found between the remineralization effects of the glass ionomer groups.

• Journal of Yeungnam Medical Science
• /
• v.11 no.1
• /
• pp.72-81
• /
• 1994

Total 55 patients with nonsmall cell lung cancer treated with radiation therapy at Department of Therapeutic Radiology, Yeungnam University Hospital, between May-1 1986 and April-30 1993 were retrospectively analyzed by clinical characteristics, failure patterns, follow up duration and survival ratio according to prognostic factors. Obtained results were as follows : 1. Male to female ratio was 17.3 2. Sixth and seventh decades were predominant age group. 3. The patients were 8 in stage I-II, 34 in stage IIIA, 13 in stage IIIb, respectively. 4. Forty five patients out of 55 were squamous cell carcinoma. 5. Primary tumor were originated from upper lobe bronchi predominantly. 6. The size of the primary tumor, lymph node involvement and the degree of differentiation were important in evaluation of prognosis. 7. In conclusion, for patients with poor prognostic factors systemic chemotherapy and multidisciplinary approach were recommended for better treatment outcome and improvement of survival.

• Progress in Medical Physics
• /
• v.24 no.3
• /
• pp.198-203
• /
• 2013

Generally, to evaluate gated radiation therapy, moving phantoms are used to simulate organ motion. Since the target moves in every direction, we need to take into account motion in each direction. This study proposes methods to evaluate gated radiation therapy using gamma index analysis and to visualize adequate gating window sizes according to motion ranges. The moving phantom was fabricated to simulate motion in the craniocaudal direction. This phantom consisted of a moving platform, the I'm MatriXX, and solid water phantoms. A 6 MV photon filed with a field size of $4{\times}4cm^2$ was delivered to the phantom using the gating system, while the phantom moved in the 1-, 2-, 3-, 4-, and 5-cm motion ranges. The gating windows were set at 40~60%, 30~40%, and 0~90%, respectively. The I'm MatriXX acquired the dose distributions for each scenario and the dose distributions were compared with a $4{\times}4cm^2$ static filed. The tolerance of the gamma index was set at 3%/3 mm. The greater the gating window, the lower the pass rate, and the greater the motion range, the lower the pass rate in this study. In case treatment without gated radiation therapy for the target with motion of 2 cm, the pass rate was less than 96%. But it was greater than 99% when gated radiation therapy was used. However gated radiation therapy was used for the target with motion greater than 4 cm, the pass rate could not be greater than 97% when gating window was set as 30~70%. But when the gating window set as 40~60%, the pass rate was greater than 99%.

• Investigative Magnetic Resonance Imaging
• /
• v.14 no.1
• /
• pp.31-40
• /
• 2010

Purpose : To compare the relative values of various fast breath-hold imaging sequences for superparamagnetic iron-oxide (SPIO)-enhanced hepatic MRI for the assessment of solid focal lesions with a 3T MRI unit. Materials and Methods : 102 consecutive patients with one or more solid malignant hepatic lesions were evaluated by spoiled gradient echo (GRE) sequences with three different echo times (2.4 msec [GRE_2.4], 5.8 msec [GRE_5.8], and 10 msec [GRE_10]) for $T2^*$-weighted imaging in addition to T2-weighted turbo spin echo (TSE) sequence following intravenous SPIO injection. Image qualities of the hepatic contour, vascular landmarks and artifacts were rated by two independent readers using a four-point scale. For quantitative analysis, contrast-to-noise ratio (CNR) was measured in 170 solid focal lesions larger than 1 cm (107 hepatocellular carcinomas, nine cholangiocarcinomas and 54 metastases). Results : GRE_5.8 showed the highest mean points for hepatic contour, vascular anatomy and imaging artifact presence among all of the subjected sequences (p<0.001) and was comparable (p=0.414) with GRE_10 with regard to lesion conspicuity. The mean CNRs were significantly higher (p<0.001) in the following order: GRE_10 ($24.4{\pm}14.5$), GRE_5.8 ($14.8{\pm}9.4$), TSE ($9.7{\pm}6.3$), and GRE_2.4 ($7.9{\pm}6.4$). The mean CNRs of CCCs and metastases were higher than those of HCCs for all imaging sequences (p<0.05). Conclusion : Regarding overall performances, GRE using a moderate echo time of 5.8 msec can provide the most reliable data among the various fast breath-hold SPIO-enhanced hepatic MRI sequences at 3T unit despite the lower CNR of GRE_5.8 compared to that of GRE_10.