***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: PURPOSE To investigate the utility of positron emission tomography ( PET ) in patients treated with stereotactic body radiotherapy ( SBRT ) for stage I non-small-cell lung cancer ( NSCLC ) on prospect i ve institutional trials . PATIENTS AND METHODS Fifty-eight patients with medically inoperable stage I NSCLC who participated in prospect i ve phase I and II trials of SBRT , had > or=2 years of follow-up , and received FDG-PET imaging are the focus of this evaluation . Fifty-seven of 58 patients received pre-SBRT FDG-PET  to confirm stage I status . All patients received stereotactic body frame immobilization and treatment with 7 - 10 photon beams . SBRT total doses ranged from 24 to 72Gy in three fractions . No elective nodal irradiation was undertaken . Regular follow-up with planned CT imaging was performed on all patients . Post-SBRT FDG-PET was not m and ated by protocol and was typically ordered upon concern for disease recurrence . Thirty-eight post-SBRT PET studies were performed in 28 patients at a median 17.3 months following SBRT . RESULTS With a median follow-up of 42.5 months , the 3-year actuarial overall survival and local control for this select subset of our SBRT experience were 48.9 % and 74.8 % , respectively . Pre-SBRT FDG-PET SUV did not predict 3-year overall survival or local control . Fourteen of 57 patients eventually failed in nodal stations by CT and /or PET . Isolated first site of failure was nodal in 6 patients ( 10 % ) . Out of 28 patients with post-SBRT PET , 4 ( 14 % ) had delayed PET imaging ( 22 - 26 months after SBRT ) showing moderate hypermetabolic activity ( SUV 2.5 - 5.07 ) , but no evidence of local , nodal , or distant recurrence by clinical examination and conventional imaging performed 20 - 26 months following these concerning PET findings . CONCLUSIONS Isolated nodal recurrence following PET-staged I NSCLC treated with SBRT is uncommon . Moderate post-SBRT PET hypermetabolic activity may persist 2 years following treatment without definite evidence of recurrence . Further study is needed to confirm these results in larger population s with longer follow-up Objective To report serial 18F-fluorodeoxyglucose ( 18F-FDG ) positron emission tomography (PET)/computed tomography ( CT ) tumor response following CyberKnife radiosurgery for stage IA non-small cell lung cancer ( NSCLC ) . Methods Patients with biopsy-proven inoperable stage IA NSCLC were enrolled into this IRB-approved study . Targeting was based on 3 - 5 gold fiducial markers implanted in or near tumors . Gross tumor volumes ( GTVs ) were contoured using lung windows ; margins were exp and ed by 5 mm to establish the planning treatment volumes ( PTVs ) . Doses ranged from 42 - 60 Gy in 3 equal fractions . 18F-FDG PET/CT was performed prior to and at 3 - 6-month , 9 - 15 months and 18 - 24 months following treatment . The tumor maximum st and ardized uptake value ( SUVmax ) was recorded for each time point . Results Twenty patients with an average maximum tumor diameter of 2.2 cm were treated over a 3-year period . A mean dose of 51 Gy was delivered to the PTV in 3 to 11 days ( mean , 7 days ) . The 30-Gy isodose contour extended an average of 2 cm from the GTV . At a median follow-up of 43 months , the 2-year Kaplan-Meier overall survival estimate was 90 % and the local control estimate was 95 % . Mean tumor SUVmax before treatment was 6.2 ( range , 2.0 to 10.7 ) . During early follow-up the mean tumor SUVmax remained at 2.3 ( range , 1.0 to 5.7 ) , despite transient elevations in individual tumor SUVmax levels attributed to peritumoral radiation-induced pneumonitis visible on CT imaging . At 18 - 24 months the mean tumor SUVmax for controlled tumors was 2.0 , witha narrow range of values ( range , 1.5 to 2.8 ) . A single local failure was confirmed at 24 months in a patient with an elevated tumor SUVmax of 8.4 . Conclusion Local control and survival following CyberKnife radiosurgery for stage IA NSCLC is exceptional . Early transient increases in tumor SUVmax are likely related to radiation-induced pneumonitis . Tumor SUVmaxvalues return to background levels at 18 - 24 months , enhancing 18F-FDG PET/CT detection of local failure . The value of 18F-FDG PET/CT imaging for surveillance following lung SBRT deserves further study This study was performed to investigate the feasibility of FDG- and L-[methyl-11C]methionine (Met)-PET for the follow up of lung cancer after stereotactic radiotherapy ( SRT ) . Nine patients ( pt ) with solitary lung cancer underwent SRT . Met- and FDG-PET studies were performed one week before SRT and from one week to 8 months after SRT . Responses to SRT were complete in 2 pt and partial in 7 pt .  Met- and FDG-PET scan showed high tracer uptake in all tumors before SRT . After SRT , st and ardized uptake values ( SUV ) of FDG and Met changed concordantly . Both decreased with time in 5 pt but did not decrease steadily in 4 pt , where 2 pt showed an increase at 1 to 2 weeks after SRT and 2 pt showed an increase at more than 3 months after SRT . The former appears to reflect the acute reaction to SRT and the latter radiation-induced pneumonitis . Although the addition of Met-PET did not provide additional information over FDG-PET , FDG- and Met-PET could be used to evaluate the treatment effect of SRT PURPOSE A Phase I dose escalation study of stereotactic body radiation therapy to assess toxicity and local control rates for patients with medically inoperable Stage I lung cancer . METHODS AND MATERIAL S All patients had non-small-cell lung carcinoma , Stage T1a or T1b N0 , M0 . Patients were immobilized in a stereotactic body frame and treated in escalating doses of radiotherapy beginning at 24 Gy total ( 3 x 8 Gy fractions ) using 7 - 10 beams . Cohorts were dose escalated by 6.0 Gy total with appropriate observation periods . RESULTS The maximum tolerated dose was not achieved in the T1 stratum ( maximum dose = 60 Gy ) , but within the T2 stratum , the maximum tolerated dose was realized at 72 Gy for tumors larger than 5 cm . Dose-limiting toxicity included predominantly bronchitis , pericardial effusion , hypoxia , and pneumonitis . Local failure occurred in 4/19 T1 and 6/28 T2 patients . Nine local failures occurred at doses < or = 16 Gy and only 1 at higher doses . Local failures occurred between 3 and 31 months from treatment . Within the T1 group , 5 patients had distant or regional recurrence as an isolated event , whereas 3 patients had both distant and regional recurrence . Within the T2 group , 2 patients had solitary regional recurrences , and the 4 patients who failed distantly also failed regionally . CONCLUSIONS Stereotactic body radiation therapy seems to be a safe , effective means of treating early-stage lung cancer in medically inoperable patients . Excellent local control was achieved at higher dose cohorts with apparent dose-limiting toxicities in patients with larger tumors PURPOSE Routine assessment was made of tumor metabolic activity as measured by 18F-fluorodeoxyglucose ( FDG ) positron emission tomography ( PET ) in Stage I non-small-cell lung cancer ( NSCLC ) . This report describes PET correlates prospect ively collected after stereotactic body radiotherapy ( SBRT ) for patients with medically inoperable NSCLC . METHODS AND MATERIAL S 14 consecutive patients with medically inoperable Stage I NSCLC were enrolled . All patients received SBRT to 60 - 66 Gy in three fractions . Patients underwent serial planned FDG-PET/computed tomography fusion imaging before SBRT and at 2 , 26 , and 52 weeks after SBRT . RESULTS With median follow-up of 30.2 months , no patients experienced local failure . One patient developed regional failure , 1 developed distant failure , and 1 developed a second primary . The median tumor maximum st and ardized uptake value ( SUV(max ) ) before SBRT was 8.70 . The median SUV(max ) values at 2 , 26 , and 52 weeks after SBRT were 6.04 , 2.80 , and 3.58 , respectively . Patients with low pre-SBRT SUV were more likely to experience initial 2-week rises in SUV , whereas patients with high pre-SBRT SUV commonly had SUV declines 2 weeks after treatment ( p = 0.036 ) . Six of 13 patients had primary tumor SUV(max ) > 3.5 at 12 months after SBRT but remained without evidence of local disease failure on further follow-up . CONCLUSIONS A substantial proportion of patients may have moderately elevated FDG-PET SUV(max ) at 12 months without evidence of local failure on further follow-up . Thus , slightly elevated PET SUV(max ) should not be considered a surrogate for local treatment failure . Our data do not support routine serial FDG-PET/computed tomography for follow-up of patients receiving SBRT for Stage I NSCLC PURPOSE To compare the quality -adjusted life expectancy and overall survival in patients with Stage I non-small-cell lung cancer ( NSCLC ) treated with either stereotactic body radiation therapy ( SBRT ) or surgery .  METHODS AND MATERIAL S We constructed a Markov model to describe health states after either SBRT or lobectomy for Stage I NSCLC for a 5-year time frame . We report various treatment strategy survival outcomes stratified by age , sex , and pack-year history of smoking , and compared these with an external outcome prediction tool ( Adjuvant ! Online ) . RESULTS Overall survival , cancer-specific survival , and other causes of death as predicted by our model correlated closely with those predicted by the external prediction tool . Overall survival at 5 years as predicted by baseline analysis of our model is in favor of surgery , with a benefit ranging from 2.2 % to 3.0 % for all cohorts . Mean quality -adjusted life expectancy ranged from 3.28 to 3.78 years after surgery and from 3.35 to 3.87 years for SBRT . The utility threshold for preferring SBRT over surgery was 0.90 . Outcomes were sensitive to quality of life , the proportion of local and regional recurrences treated with st and ard vs. palliative treatments , and the surgery- and SBRT-related mortalities . CONCLUSIONS The role of SBRT in the medically operable patient is yet to be defined . Our model indicates that SBRT may offer comparable overall survival and quality -adjusted life expectancy as compared with surgical resection . Well-powered prospect i ve studies comparing surgery vs. SBRT in early-stage lung cancer are warranted to further investigate the relative survival , quality of life , and cost characteristics of both treatment paradigms This paper is an overview of the new response evaluation criteria in solid tumours :  revised RECIST guideline ( version 1 . 1 ) , with a focus on up date d contents 
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RESULTS Acute changes post-SABR predominantly appear as consolidation or ground glass opacities .
Late changes often demonstrate a modified conventional pattern of fibrosis , evolving beyond 2years after treatment .
Several CT features , including an enlarging opacity , correlate with recurrence .
Although  PET SUVmax may rise immediately post-SABR , an SUVmax⩾5 carries a high predictive value of recurrence .
CT density changes are common post-SABR .
The available evidence suggests that recurrent disease should be suspected if high-risk CT changes are seen with SUVmax⩾5 on PET .