High-frequency jet ventilation for complete target immobilization and reduction of planning target volume in stereotactic high single-dose irradiation of stage I non-small cell lung cancer and lung metastases.

PURPOSE: To demonstrate the feasibility of complete target immobilization by means of high-frequency jet ventilation (HFJV); and to show that the saving of planning target volume (PTV) on the stereotactic body radiation therapy (SBRT) under HFJV, compared with SBRT with respiratory motion, can be predicted with reliable accuracy by computed tomography (CT) scans at peak inspiration phase. METHODS AND MATERIALS: A comparison regarding different methods for defining the PTV was carried out in 22 patients with tumors that clearly moved with respiration. A movement span of the gross tumor volume (GTV) was defined by fusing respiration-correlated CT scans. The PTV enclosed the GTV positions with a safety margin throughout the breathing cycle. To create a PTV from CT scans acquired under HFJV, the same margins were drawn around the immobilized target. In addition, peak inspiration phase CT images (PIP-CTs) were used to approximate a target immobilized by HFJV. RESULTS: The resulting HFJV-PTVs were between 11.6% and 45.4% smaller than the baseline values calculated as respiration-correlated CT-PTVs (median volume reduction, 25.4%). Tentative planning by means of PIP-CT PTVs predicted that in 19 of 22 patients, use of HFJV would lead to a reduction in volume of >or=20%. Using this threshold yielded a positive predictive value of 0.89, as well as a sensitivity of 0.94 and a specificity of 0.5. CONCLUSIONS: In all patients, SBRT under HFJV provided a reliable immobilization of the GTVs and achieved a reduction in PTVs, regardless of patient compliance. Tentative planning facilitated the selection of patients who could better undergo radiation in respiratory standstill, both with greater accuracy and lung protection.

Stereotactic, high single-dose irradiation of stage I non-small cell lung cancer (NSCLC) using four-dimensional CT scans for treatment planning.

We reviewed response rates, local control, survival and side effects after non-fractionated stereotactic high single-dose body radiation therapy for lung tumors. Forty patients with stage I non-small cell lung cancer (NSCLC) underwent radiosurgery involving single-dose irradiation. The standard dose prescribed to the isocenter was 30Gy with an axial safety margin of 10mm and a longitudinal safety margin of 15mm. The planning target volume (PTV) was defined using three CT scans with reference to the phases of respiration so that the movement span of the clinical target volume (CTV) was enclosed. The volume of the bronchial carcinomas varied from 4.2 to 130cm(3) (median: 19.5cm(3)), and the PTV derived from four-dimensional CT (4D-CT) scans using image fusion ranged from 15.6 to 390.5cm(3) (median: 101cm(3)). Tumor size ranged from 1.7 to 10cm at largest focuses. Follow-up periods varied from 6.0 to 61.5 months (median: 20 months). We observed three local tumor recurrences, resulting in an actuarial local tumor control of 81% at 3 years. With the exception of two rib fractures, no serious late toxicity was observed. The overall survival probability rates were: 2 years: 66%, 3 years: 53% (median overall survival: 37 months). Cancer-specific survival probability was: 2 years: 71%, 3 years: 57%. Non-fractionated high single-dose SBRT for NSCLC is more convenient for the patient and less time-consuming than hypofractionated SBRT, but data dealing with this method are still scanty. This alternative treatment results in favourable local control and acceptable toxicity.

Stereotactic, single-dose irradiation of stage I non-small cell lung cancer and lung metastases.

BACKGROUND: We prospectively reviewed response rates, local control, and side effects after non-fractionated stereotactic high single-dose body radiation therapy for lung tumors. METHODS: Fifty-eight patients underwent radiosurgery involving single-dose irradiation. With 25 patients, 31 metastases in the lungs were irradiated; with each of 33 patients, stage I non-small cell lung cancer (NSCLC) was subject to irradiation. The standard dose prescribed to the isocenter was 30 Gy with an axial safety margin of 10 mm and a longitudinal safety margin of 15 mm. The planning target volume (PTV) was defined using three CT scans with reference to the phases of respiration so that the movement span of the clinical target volume (CTV) was enclosed. RESULTS: The volume of the metastases (CTV) varied from 2.8 to 55.8 cm3 (median: 6.0 cm3) and the PTV varied from 12.2 to 184.0 cm3 (median: 45.0 cm3). The metastases ranged from 0.7 to 4.5 cm in largest diameter. The volume of the bronchial carcinomas varied from 4.2 to 125.4 cm3 (median: 17.5 cm3) and the PTV from 15.6 to 387.3 cm3 (median: 99.8 cm3). The bronchial carcinomas ranged from 1.7 to 10 cm in largest diameter. Follow-up periods varied from 6.8 to 63 months (median: 22 months for metastases and 18 months for NSCLC). Local control was achieved with 94% of NSCLC and 87% of metastases. No serious symptomatic side effects were observed. According to the Kaplan-Meier method the overall survival probability rates of patients with lung metastases were as follows: 1 year: 97%, 2 years: 73%, 3 years: 42%, 4 years: 42%, 5 years: 42% (median survival: 26 months); of those with NSCLC: 1 year: 83%, 2 years: 63%, 3 years: 53%, 4 years: 39%: (median survival: 20.4 months). CONCLUSION: Non-fractionated single-dose irradiation of metastases in the lungs or of small, peripheral bronchial carcinomas is an effective and safe form of local treatment and might become a viable alternative to invasive techniques.