Abstract
Purpose: To evaluate planning quality of Stereotactic body Radiotherapy (SBRT) with multiple lungmetastases generated by the Pinnacle and Tomotherapy planning systems, respectively. Methods and Materials: Nine randomly selected patients diagnosed with non-small cell lung carcinoma with multiple lesions were planned with Philips Pinnacle (version 9.2, Fitchburg, WI) and Tomotherapy (version 4.2, Madison, WI), respectively. Both coplanar and non-coplanar IMRT plans were generated on Pinnacle system. A total dose of 60 Gy was prescribed to cover 95% of Planning Target Volume (PTV) in 3 fractions based on the RTOG0236 protocol prescription [1]. All plans with single isocenter setting were used for multiple lesions planning. A set of nine static beams were used for Pinnacle plansusing Direct Machine Parameters Optimization (DMPO) algorithm of RTOT0236 dose constraints. Planning outcomes such as minimum and mean doses, V95, D95 (95% of target volume receivesprescription dose), D5, and D1 to PTV, maximum dose to heart, esophagus, cord, trachea, brachial plexus, rib, chest wall, and liver, mean dose toliver, total lung, right and left lung, volume of chest wall receives 30 Gy, volume of lungs receives 5 Gy and 20 Gy (V5 and V20), conformity index (CI) and heterogeneity index (HI) were all reported for evaluation. Results: Mean volume of PTV was 37.77 ± 23.4 cm3. D95 of PTV with Tomotherapy, coplanar, non-coplanar plan was 60.2 ± 0.3 Gy, 58.6 ± 1.2 Gy, and 59.1 ± 0.7 Gy, respectively. Mean dose to PTV was lower for Tomotherapy (p 5 (p 1 (p = 0.001). CI was higher with Tomotherapyplans (p p 5 which needs more attention for toxicity analysis.
Highlights
With early stage primary non-small-cell lung cancer (NSCLC) of T1 or T2 lesion not including metastases, usually the surgical resection was chosen to manage using a lobectomy technique
Stereotactic body Radiotherapy (SBRT) treatment opens a new era for treating the lung metastases compared to the conventional surgery, which was invasive with higher risks
Our study has shown that Tomotherapy has better coverage and less normal tissues doses among those 9 patients, as they only concentrate on the feasibility of planning multiple lung lesions with one isocenter
Summary
With early stage primary non-small-cell lung cancer (NSCLC) of T1 or T2 lesion not including metastases, usually the surgical resection was chosen to manage using a lobectomy technique. In order to acquire the most valuable dosimetric information and understand how different radiation schedules is being adopted with fractionated scheme for SBRT in lung, we have listed the Biological Equivalent Dose (BED) derived from the report of Kavanagh et al [9]. This simple table has not correctly predicted a linear quadratic correlation between the lung lesions and late responding normal tissues; it does support the concept of SBRT which could generate a higher equivalent dose for hypofractionated treatment schemes (see Table 1)
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