The effect of environmental radiation of radiotherapy workplace on stereotactic radiation therapy plan dose verification using an Exradin W1 scintillator detector / 中华放射医学与防护杂志

Objective:To study the influence of environmental radiation of radiotherapy workplace on the stereotactic radiation therapy(SRT) plan absolute dose verification with plastic scintillator detector Exradin W1.Methods:The computed tomography (CT) image of the stereotactic dose verification phantom (SDVP) was scanned and imported into the treatment planning system. Three schemes, including 3 cm × 3 cm to 20 cm × 20 cm square gradient field irradiation, virtual planning target volume(PTV) non-coplanar arcs irradiation and 10 cases of volumetric modulated arc radiotherapy SRT (VMAT SRT) clinical plan verification, were measured with or without a home-made shield over the photodiode. Measurements were recorded to analyze the impact of environmental radiation on dose measurement under different conditions.Results:The noise effect of the photodiode increased with the the lager open field size, and decreased with the reduced distance between the photodiode and isocenter. The contribution of photodiode noise effect increase with the lager non-coplanar arc field size, with the largest up to 4.16%. As for the clinical SRT plan verification measurement, the relative difference between the SRT plan measurements and treatment planning system(TPS) before and after shielding were (1.39±1.05)% and (0.59±1.03)%, respectively ( t=-5.343, P < 0.05). and for W1 vs. A16 microchamber was (1.22±1.56)% and (0.42±1.42)%, respectively ( t=-5.414, P < 0.05). Conclusions:The measurements of Exradin W1 are in good agreement with the TPS result and the ionization chamber measurements, but its accuracy is easily affected by the environmental radiation of radiotherapy workplace. To measure non-coplanar radiation, the photodiode should be placed as far away as possible from the isocenter and be properly shielded, which can effectively improve the accuracy and stability of the measurement and provide a strong guarantee for clinical precision radiotherapy.

Cyberknife stereotactic body radiotherapy for liver metastases from prostate cancer / 中华男科学杂志

Objective@#To investigate the effectiveness and adverse effects of Cyberknife stereotactic body radiotherapy (SBRT) on liver metastases from PCa.@*METHODS@#From June 2009 to September 2016, we treated 20 cases of PCa liver metastases by Cyberknife SBRT, at a total dose of 36 (30－50) Gy, on 1－3 liver metastatic lesions, for 3－5 times, with a prescription isodose line of 70－92%. We assessed the therapeutic effect according to the modified Response Evaluation Criteria in Solid Tumors (mRECIST), calculated the survival and disease-control rates using the Kaplan-Meier method, and analyzed the adverse events based on the National Cancer Institute Common Terminology Criteria for Adverse Events－Version 4.0 (CTCAE 4.0).@*RESULTS@#Of all the cases treated, complete response (CR) was found in 8 (40.0%), partial response (PR) in 9 (45.0%), stable disease (SD) in 2 (10.0%), and progressive disease (PD) in 1 (5.0%), with a local control rate (CR+PR) of 85.0% and a disease-control rate (CR+PR+SD) of 95.0%. Among the 14 patients with elevated PSA, 10 (71.4%) showed a significant decrease after treatment. The median follow-up time was 17 months, the 1- and 2-year survival rates were 85.0% and 15.0%, respectively, and the median survival time of the 20 patients was 16.5 months (95% CI: 12.12－22.88). Cyberknife SBRT was well tolerated in all the patients, with only a few mild adverse events (mainly grades 1 and 2 but no 4 and 5) during the whole course of treatment.@*CONCLUSIONS@#Cyberknife SBRT is safe and effective in the treatment of PCa liver metastases, with a high local control rate, and capable of reducing the PSA level and raising the long-term survival rate of the patients.

Stereotactic body radiation therapy for liver oligo-recurrence and oligo-progression from various tumors

PURPOSE: To evaluate the outcomes of stereotactic body radiation therapy (SBRT) for patients with liver oligo-recurrence and oligo-progression from various primary tumors. MATERIALS AND METHODS: Between 2002 and 2013, 72 patients with liver oligo-recurrence (oligo-metastasis with a controlled primary tumor) and oligo-progression (contradictory progression of a few sites of disease despite an overall tumor burden response to therapy) underwent SBRT. Of these, 9 and 8 patients with uncontrollable distant metastases and patients immediate loss to follow-up, respectively, were excluded. The total planning target volume was used to select the SBRT dose (median, 48 Gy; range, 30 to 60 Gy, 3–4 fractions). Toxicity was evaluated using the Common Toxicity Criteria for Adverse Events v4.0. RESULTS: We evaluated 55 patients (77 lesions) treated with SBRT for liver metastases. All patients had controlled primary lesions, and 28 patients had stable lesions at another site (oligo-progression). The most common primary site was the colon (36 patients), followed by the stomach (6 patients) and other sites (13 patients). The 2-year local control and progression-free survival rates were 68% and 22%, respectively. The 2- and 5-year overall survival rates were 56% and 20%, respectively. The most common adverse events were grade 1–2 fatigue, nausea, and vomiting; no grade ≥3 toxicities were observed. Univariate analysis revealed that oligo-progression associated with poor survival. CONCLUSION: SBRT for liver oligo-recurrence and oligo-progression appears safe, with similar local control rates. For liver oligo-progression, criteria are needed to select patients in whom improved overall survival can be expected through SBRT.

The role of stereotactic radiation therapy and whole-brain radiotherapy in the treatment of multiple brain metastases / 中华放射肿瘤学杂志

ObjectiveTo summarize the results of stereotactic radiation therapy (SRT) with or without whole-brain radiotherapy (WBRT) in the treatment of multiple brain metastasis.MethodsFrom May 1995 to April 2010,totally 98 newly diagnosed multiple (2 - 13 lesions) brain metastases patients were treated in our centre.Forty-four patients were treated with SRT alone and 54 with SRT + WBRT.Dose fractionation schemes were 15 -26 Gy in 1 fraction or 24.0 -52.5 Gy in 2 - 15 fractions with 3.5 - 12.0 Gy per fraction,depending on the tumor volume,location,and history of prior irradiation.Kaplan-Meier and Cox proportional hazards regression analyses were used for survival analysis.The median age of the whole group was 55 years.The survival time was calculated from the date of radiation treatment to the day of death by any cause.ResultsThe median follow-up time for the whole group was 12 months,and the follow-up rate was 100％.The median overall survival time was 13.5 months for the whole group,there was no difference between SRT alone group and SRT + WBRT group ( 13.0 months vs.13.5 months,χ2 =0.31,P =0.578 ).The Karnofsky Performance Score ( KPS) at the time of treatment ( χ2 =6.25,P =0.012 ),the interval between the diagnosis of the primary tumor and brain metastases ( χ2 =7.34,P =0.025 ) and the status of extracranial metastases ( χ2 =4.20,P =0.040) were independent prognosis factors for survival in multivariate analyses.ConclusionsStereotactic radiation therapy is an effective and alternative treatment choice for multiple brain metastases.

Development of Movement Analysis Program and Its Feasibility Test in Streotactic Body Radiation Threrapy / 의학물리

Respiratory gated radiation therapy and stereotactic body radiation therapy require identical tumor motions during each treatment with the motion detected in treatment planning CT. Therefore, this study developed a tumor motion monitoring and analysis system during the treatments employing RPM data, gated setup OBI images and a data analysis software. A respiratory training and guiding program which improves the regularity of breathing was used to patients. The breathing signal was obtained by RPM and the recorded data in the 4D console was read after treatment. The setup OBI images obtained gated at 0% and 50% of breathing phases were used to detect the tumor motion range in crenio-caudal direction. By matching the RPM data recorded at the OBI imaging time, a factor which converts the RPM motion to the tumor motion was computed. RPM data was entered to the institute developed data analysis software and the maximum, minimum, average of the breathing motion as well as the standard deviation of motion amplitude and period was computed. The computed result is exported in an excel file. The conversion factor was applied to the analyzed data to estimate the tumor motion. The accuracy of the developed method was tested by using a moving phantom, and the efficacy was evaluated for 10 stereotactic body radiation therapy patients. For the sine wave motion of the phantom with 4 sec of period and 2 cm of peak-to-peak amplitude, the measurement was slightly larger (4.052 sec) and the amplitude was smaller (1.952 cm). For patient treatment, one patient was evaluated not to qualified to SBRT due to the usability of the breathing, and in one patient case, the treatment was changed to respiratory gated treatment due the larger motion range of the tumor than treatment planed motion. The developed method and data analysis program was useful to estimate the tumor motion during treatment.

Evolution of Radiotherapy: High-precision Radiotherapy

Technological advances that have been achieved over the last two decades in the area of treatment planning and sophisticated and complicated hardware capabilities, such as computer-controlled treatments, multileaf collimators, and incorporating imaging devices into treatment machines, enable clinical implementation of high-precision radiotherapy in field of radiation oncology. High-precision radiotherapy allows the delivery of increased tumor doses with relative sparing of normal tissues compared to 3 -dimensional radiotherapy and conventional techniques. Preliminary clinical experiences of high precision radiation therapy have been encouraging by high rates of local control and decrease of toxicity. This article provides an overview of high precision radiotherapy such as intensity-modulated radiotherapy, stereotactic radiation therapy, image-guided radiotherapy, and charged particle therapy.

Locally Advanced, Unresectable Pancreatic Cancer Treated by Stereotactic Radiation Therapy / 대한방사선종양학회지

PURPOSE: In order to find out whether stereotactic radiation therapy (RT) using CyberKnife (CK) could improve survival rate and lower acute toxicity compared to conventional RT. MATERIALS AND METHODS: From April 2003 through April 2004, 19 patients with Eastern Cooperative Oncology Group (ECOG) performance status 80 cc (p-value80 cc showed better survival rate. CONCLUSION: In terms of survival, the efficacy of stereotactic radiation therapy using CK was found to be superior or similar to other recent studies achieved with conventional RT with intensive chemotherapy, high dose conformal RT, intraoperative RT (IORT), or intensity modulated RT (IMRT). Furthermore, severe toxicity was not observed. Short treatment time in relation to the short life expectancy gave patients more convenience and, finally, quality of life would be increased. Consequently, this could be regarded as an effective novel treatment modality for locally advanced, unresectable pancreas cancer. PTV would be a helpful prognostic factor for CK.

Beam Shaping by Independent Jaw Closure in Stereotactic Radiotherapy / 대한방사선종양학회지

INTRODUCTION: Stereotactic radiation therapy (SRT) can deliver highly focused radiation to a small and spherical target lesion with very high degree of mechanical accuracy. For non-spherical and large lesions, however, inclusion of the neighboring normal structures within the high dose radiation volume is inevitable in SRT. This is to report the beam shaping using the partial closure of the independent jaw in SRT and the verification of dose calculation and the dose display using a home-made soft ware. MATERIALS & METHODS: Authors adopted the idea to partially close one or more independent collimator jaw(s) in addition to the circular collimator cones to shield the neighboring normal structures while keeping the target lesion within the radiation beam field at all angles along the arc trajectory. The output factors (OF's) and the tissue-maximum ratios (TMR's) were measured using the micro ion chamber in the water phantom dosimetry system, and were compared with the theoretical calculations. A film dosimetry procedure was performed to obtain the depth dose profiles at 5 cm, and they were also compared with the theoretical calculations, where the radiation dose would depend on the actual area of irradiation. Authors incorporated this algorithm into the home-made SRT software for the isodose calculation and display, and was tried on an example case with single brain metastasis. The dose-volume histograms (DVH's) of the planning target volume (PTV) and the normal brain derived by the control plan were reciprocally compared with those derived by the plan using the same arc arrangement plus the independent collimator jaw closure. RESULTS: When using 5.0 cm diameter collimator, the measurements of the OF's and the TMR's with one independent jaw set at 30 mm (unblocked), 15.5 mm, 8.6 mm, and 0 mm from the central beam axis showed good correlation to the theoretical calculation within 0.5% and 0.3% error range. The dose profiles at 5 cm depth obtained by the film dosimetry also showed very good correlation to the theoretical calculations. The isodose profiles obtained on the home-made software demonstrated a slightly more conformal dose distribution around the target lesion by using the independent jaw closure, where the DVH's of the PTV were almost equivalent on the two plans, while the DVH's for the normal brain showed that less volume of the normal brain receiving high radiation dose by using this modification than the control plan employing the circular collimator cone only. CONCLUSION: With the beam shaping modification using the independent jaw closure, authors have realized wider clinical application of SRT with more conformal dose planning. Authors believe that SRT, with beam shaping ideas and efforts, should no longer be limited to the small spherical lesions, but be more widely applied to rather irregularly shaped tumors in the intracranial and the head and neck regions.

Fractionated Stereotactic Radiation Therapy for Intracranial Malignant Tumor: Preliminary Results of Clinical Application / 대한암학회지

PURPOSE: Fractionated stereotactic radiation therapy(FSRT) is a new modality that combines the accurate focal dose delivery of stereotactic radiosurgery with the biological advantages of conventional radiotherapy. We report our early experience using FSRT for intracranial malignant tumor. MATERIALS AND METHODS: Between October 1995 and December 1996, 16 patients(9 males and 7 females aged between 10~64 years) with central nerve system malignancy were treated using FSRT. Sixteen patients had the following diagnosis: 6 high-grade gliomas, 1 pineoblastoma, 4 germinomas, 2 medulloblastomas, and 3 solitary brain metastases. Using the Gill-Thomas-Cosman relocatable head frame and multiple non-coplanar therapy, the daily dose of 2 Gy(3 Gy in metastasis) was irradiated at 85~100% isodose surface. RESULTS: Although the follow-up period is relatively short(range; 2~18 months), post- treatment clinical courses in 16 patients have been consistent with changes similar to those found after conventional radiation therapy. No significant adverse effects were observed in our neurological and radiological studies. Four out of 5 patients with high grade glioma died from progressive disease, surviving from 7 to 17 months(median 14 months), but patients with pineoblastoma, germinoma and medulloblastoma showed no evidence of recurrence. All patients with metastasis obtained a neurologic response, but two among them died with extracranial progression and one die from multiple intracranial metastasis.In overall patient setup with scalp measurements, reproducibility was found to have mean of 1.1+/-0.6 mm from the baseline reading. CONCLUSION: FSRT and relocatable stereotactic head frames were well tolerated with minimal transient acute side effects. Subacute or late complications were not observed, because the follow-up period was short. We expect that FSRT might be a good indication for; recurrent disease with previous radiation therapy history, tumors of relatively large volume, lesions adjacent to radiosensitive organs, and as a boost, following conventional radiation therapy.

Fractionated Stereotactic Radiation Therapy for Intracranial Benign Tumor: Preliminary Results of Clinical Application / 대한방사선종양학회지

PURPOSE: With the development of stereotactic immobilization systems capable of reliable serial repositioning, fractionated stereotactic radiation therapy (FSRT) offers the potential for an improved treatment outcome by excellent dose delivery, and dose distribution characteristics with the favorable radiobiological properties of fractionated irradiation. We describe our initial experience using FSRT for the treatment of intracranial benign tumor. MATERIALS AND METHODS: Between August 1995 and December 1996, 15 patients (7 males and 8 females aged 6-70 years) were treated with FSRT. The patients had the following diagnosis : pituitary adenoma (10) including one patient who previously had received radiotherapy, craniopharyngioma (2), acoustic neurinoma (1), meningioma (2). Using the Gill-Thomas-Cosman relocatable head frame and multiple non-coplanar therapy, the daily dose of 2Gy was irradiated at 90% to 100% isodose surface of the isocenter. The collimator sizes ranged from 26mm to 70mm. RESULTS: In all patients except one follow-up lost, disease was well- controlled. Acute complication was negligible and no patient experienced cranial nerve neuropathies and radiation necrosis. In overall patient setup with scalp measurements, reproducibility was found to have mean of 1.1+/-0.6mm from the baseline reading. CONCLUSION: Relocatable stereotactic system for FSRT is highly reproducible and comfortable. Although the follow-up period was relatively short, FSRT is considered to be a safe and effective radiation technique as the treatment of intracranial tumor. But the fractionation schedule (fraction size, overall treatment time and total dose) still remains to be solved by further clinical trials.

Excellent Local Tumor Response after Fractionated Stereotactic Radiation Therapy for Locally Recurrent Nasopharynx Cancer / 대한치료방사선과학회지

PURPOSE: This study is to report experience with Fractionated Stereotactic Radiation Therapy (FSRT) for locally recurrent nasopharynx cancer after curative conventional radiation therapy. MATERIALS AND METHODS: Three patients with locally recurrent and symptomatic nasopharynx cancer were given FSRT as reirradiation method between the period of September of 1995 and August of 1996. For two patients, application of FSRT is their third radiation therapy directed to the nasopharynx. Two patients were given low dose chemotherapy as radiation sensitizer concurrently with FSRT. Authors used 3-dimensional coordinate system by individually made, relocatable Gill-Thomas-Cosman (GTC) stereotactic frame and multiple non-coplanar arc therapy dose planning was done using XKnife-3. Total of 45 Gy/18 fractions or 50 Gy/20 fractions were given. RESULTS: Authors observed satisfactory symptomatic improvement and remarkable objective tumor size decrease by follow-up MR images taken 1 month post-FSRT in all three patients, while no neurologic side effect attributable to reirradiation was noticed. Two died at 7 and 9 months with loco-regional and distant seeding outside FSRT field, while one patient is living for 4 month. CONCLUSION: Authors experienced satisfactory therapeutic effectiveness and safety of FSRT as reirradiation method for locally recurrent nasopharynx cancer. Development of more effective systemic chemotherapeutic regimen is desired for distant metastasis.

Value of stereotactic radiosurgery in patients with multiple brain metastases / 中华放射肿瘤学杂志

Objective To analyze the prognostic factors and evaluate the effect of stereotactic radiosurgery for patients with multiple brain metastases. Methods Comparison was made in 53 such patients treated by stereotactic radiosurgery plus radiotherapy and 53 treated by radiotherapy alone. Patients were matched paired according to the following criteria: age, Karnofsky performance scale(KPS) before treatment, extent of systemic cancer and number of brain metastasis.Fourty patients had stereotactic radiosurgery, 13 patients stereotactic fractionated radiosurgery. In the stereotactic radiosurgery group, the patients were given a mean marginal dose of 20?Gy. Methods of stereotactic fractionated radiosurgery was 4 12?Gy per fraction, twice a week to a total dose of 15 30?Gy. Whole brain radiotherapy was given immediately after stereotactic radiosurgery. For patients treated by radiotherapy alone, the entire brain was treated by 30 40?Gy in 3 4 weeks. Results The median survival was 11.6 months in stereotactic radiosurgery plus radiotherapy and 6.7 months in radiotherapy alone. The one year survival rate and one year local control rate were 44.3%,17.1% and 50.9%,13.2%. Those with KPS increased after treatment gave 1 year survivals of 69.8% and 30.2%, respectively. The validity rates in CT or MRI three months after treatment were 82.0% and 55.0%.The difference in the two groups was found to be statistically significant (P