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Influence of respiratory motion management technique on radiation pneumonitis risk with robotic stereotactic body radiation therapy.

ABSTRACT: PURPOSE/OBJECTIVES:For lung stereotactic body radiation therapy (SBRT), real-time tumor tracking (RTT) allows for less radiation to normal lung compared to the internal target volume (ITV) method of respiratory motion management. To quantify the advantage of RTT, we examined the difference in radiation pneumonitis risk between these two techniques using a normal tissue complication probability (NTCP) model. MATERIALS/METHOD:20 lung SBRT treatment plans using RTT were replanned with the ITV method using respiratory motion information from a 4D-CT image acquired at the original simulation. Risk of symptomatic radiation pneumonitis was calculated for both plans using a previously derived NTCP model. Features available before treatment planning that identified significant increase in NTCP with ITV versus RTT plans were identified. RESULTS:Prescription dose to the planning target volume (PTV) ranged from 22 to 60 Gy in 1-5 fractions. The median tumor diameter was 3.5 cm (range 2.1-5.5 cm) with a median volume of 14.5 mL (range 3.6-59.9 mL). The median increase in PTV volume from RTT to ITV plans was 17.1 mL (range 3.5-72.4 mL), and the median increase in PTV/lung volume ratio was 0.46% (range 0.13-1.98%). Mean lung dose and percentage dose-volumes were significantly higher in ITV plans at all levels tested. The median NTCP was 5.1% for RTT plans and 8.9% for ITV plans, with a median difference of 1.9% (range 0.4-25.5%, pairwise P < 0.001). Increases in NTCP between plans were best predicted by increases in PTV volume and PTV/lung volume ratio. CONCLUSIONS:The use of RTT decreased the risk of radiation pneumonitis in all plans. However, for most patients the risk reduction was minimal. Differences in plan PTV volume and PTV/lung volume ratio may identify patients who would benefit from RTT technique before completing treatment planning.

SUBMITTER: Chapman CH

PROVIDER: S-EPMC6036380 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Influence of respiratory motion management technique on radiation pneumonitis risk with robotic stereotactic body radiation therapy.

Chapman Christopher H CH McGuinness Christopher C Gottschalk Alexander R AR Yom Sue S SS Garsa Adam A AA Anwar Mekhail M Braunstein Steve E SE Sudhyadhom Atchar A Keall Paul P Descovich Martina M

Journal of applied clinical medical physics 20180426 4

<h4>Purpose/objectives</h4>For lung stereotactic body radiation therapy (SBRT), real-time tumor tracking (RTT) allows for less radiation to normal lung compared to the internal target volume (ITV) method of respiratory motion management. To quantify the advantage of RTT, we examined the difference in radiation pneumonitis risk between these two techniques using a normal tissue complication probability (NTCP) model.<h4>Materials/method</h4>20 lung SBRT treatment plans using RTT were replanned wit ...[more]

PMID: 29700954

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Project description:BackgroundRadiation pneumonitis is a critical pulmonary toxicity after irradiation of the lung. Macrolides including clarithromycin (CAM) are antibiotics. They also have immunomodulatory properties and are used to treat respiratory inflammatory diseases. Radiation pneumonitis has similar pathology to them. Adverse reactions to macrolides are few and self-limited. We thus administered CAM to patients with high-risk factors for radiation pneumonitis, and retrospectively investigated whether CAM mitigated radiation pneumonitis following stereotactic body radiotherapy (SBRT).MethodsAmong consecutive patients treated with SBRT, we retrospectively examined lung cancer patients treated with a total dose of 40-60 Gy in 5-10 fractions and followed ≥6 months. Since January 2014, CAM has been administered in patients with pretreatment predictable radiation pneumonitis high-risk factors, including idiopathic interstitial pneumonias (IIPs), and elevated Krebs von den Lungen-6 (KL-6) and/or surfactant protein D (SP-D), and in patients developing early onset radiation pneumonitis.ResultsFive hundred and eighty eligible patients were identified and divided into 445 patients during the non-CAM-administration era (non-CAM-era) (before December 2013) and 136 patients during the CAM-administration era (CAM-era) (after January 2014). Median follow-up durations were 38.0 and 13.9 months, respectively. The rates of radiation pneumonitis ≥ grade 2 and ≥ grade 3 were significantly lower in CAM-era (grade ≥2, 16% vs. 9.6%, P=0.047; grade ≥3, 3.8% vs. 0.73%, P=0.037). For patients with the pretreatment predictable high-risk factors, the rate of radiation pneumonitis ≥ grade 3 was significantly lower, and that of grade ≥2 had a lower tendency (grade ≥3, 7.2% vs. 0%, P=0.011; grade ≥2, 21% vs. 9.6%, P=0.061). For patients developing early onset radiation pneumonitis, the rate of radiation pneumonitis ≥ grade 3 was also significantly lower (23% vs. 0%, P<0.05). Multivariate analysis revealed that dose-volumetric factor, the pretreatment predictable high-risk factors and non-CAM-administration era were significantly associated with or trended toward radiation pneumonitis ≥ grade 2 and ≥ grade 3.ConclusionsCAM mitigated radiation pneumonitis following SBRT. The efficacy of CAM should be conﬁrmed in prospective studies.

Project description:The purpose of this study was to examine the characteristics and treatment plans of patients who experienced fatal radiation pneumonitis after stereotactic body radiation therapy for primary or oligometastatic lung cancer. Records of 1789 patients treated with stereotactic body radiation therapy for primary or oligometastatic lung cancer were retrospectively reviewed to identify those who developed fatal radiation pneumonitis. Twenty-three (1.3%; 18 men and 5 women) patients developed fatal radiation pneumonitis after stereotactic body radiation therapy for lung cancer; their median age was 74 years. The mean Krebs von den Lungen-6 level and percent vital capacity were 1320 U/mL and 82%, respectively. Prestereotactic body radiation therapy computed tomography revealed pulmonary interstitial change in 14 (73.7%) of 19 patients in whom computed tomography data could be reviewed. Seven (30.4%) of 23 patients had regularly used steroids. The median time duration between stereotactic body radiation therapy commencement and pneumonia symptom appearance was 75 (range: 14-204) days. Median survival time following pneumonia symptom appearance was 53 (range: 4-802) days. The 6- and 12-month overall survival rates were 34.8% and 13.0%, respectively. The 6-month overall survival rates in patients with and without heart disease were 50.0%, 16.7%, and 46.7% for heart disease existence, respectively. There were 4 patients in whom fatal radiation pneumonitis occurred within 2 months after stereotactic body radiation therapy and who died within 1 month. Three of them had no pulmonary interstitial change before stereotactic body radiation therapy, but had heart disease. In summary, the survival time in this case series was generally short but varied widely. More than half of the patients had pulmonary interstitial change before stereotactic body radiation therapy, although immediately progressive fatal radiation pneumonitis was also observed in patients without pulmonary interstitial change. True risk factors for fatal radiation pneumonitis should be examined in a prospective study with a larger cohort.

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Influence of respiratory motion management technique on radiation pneumonitis risk with robotic stereotactic body radiation therapy.

Publications

Influence of respiratory motion management technique on radiation pneumonitis risk with robotic stereotactic body radiation therapy.

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