TY - JOUR
T1 - Feasibility of non-coplanar tomotherapy for lung cancer stereotactic body radiation therapy
AU - Yang, Wensha
AU - Jones, Ryan
AU - Lu, Weiguo
AU - Geesey, Constance
AU - Benedict, Stanley
AU - Read, Paul
AU - Larner, James
AU - Sheng, Ke
PY - 2011/8
Y1 - 2011/8
N2 - To quantify the dosimetric gains from non-coplanar helical tomotherapy (HT) arcs for stereotactic body radiation therapy (SBRT) of lung cancer, we created oblique helical arcs by rotating patient's CT images. Ten, 20 and 30 degrees of yaws were introduced in the treatment planning for a patient with a hypothetical lung tumor at the upper, middle and lower portion of the right lung, and the upper and middle left lung. The planning target volume (PTV) was 43 cm3. 60 Gy was prescribed to the PTV. Dose to organs at risk (OARs), which included the lungs, heart, spinal cord and chest wall, was optimized using a 2.5 cm jaw, 0.287 pitch and modulation factor of 2.5. Composite plans were generated by dose summation of the resultant plans. These plans were evaluated for its conformity index (Rx) and percentile volume of lung receiving radiation dose of x Gy (Vx). Conformity index was defined by the ratio of x percent isodose volume and PTV. The results show that combination of non-coplanar arcs reduced R50 by 4.5%, R20 by 26% and R10 by 30% on average. Non-coplanar arcs did not affect V20but reduced V10and V5 by 10% and 24% respectively. Composite of the non-coplanar arcs also reduced maximum dose to the spinal cord by 20-39%. Volume of chest wall receiving higher than 30 Gy was reduced by 48% on average. Heart dose reduction was dependent on the location of the PTV and the choice of non-coplanar orientations. Therefore we conclude that non-coplanar HT arcs significantly improve critical organ sparing in lung SBRT without changing the PTV dose coverage.
AB - To quantify the dosimetric gains from non-coplanar helical tomotherapy (HT) arcs for stereotactic body radiation therapy (SBRT) of lung cancer, we created oblique helical arcs by rotating patient's CT images. Ten, 20 and 30 degrees of yaws were introduced in the treatment planning for a patient with a hypothetical lung tumor at the upper, middle and lower portion of the right lung, and the upper and middle left lung. The planning target volume (PTV) was 43 cm3. 60 Gy was prescribed to the PTV. Dose to organs at risk (OARs), which included the lungs, heart, spinal cord and chest wall, was optimized using a 2.5 cm jaw, 0.287 pitch and modulation factor of 2.5. Composite plans were generated by dose summation of the resultant plans. These plans were evaluated for its conformity index (Rx) and percentile volume of lung receiving radiation dose of x Gy (Vx). Conformity index was defined by the ratio of x percent isodose volume and PTV. The results show that combination of non-coplanar arcs reduced R50 by 4.5%, R20 by 26% and R10 by 30% on average. Non-coplanar arcs did not affect V20but reduced V10and V5 by 10% and 24% respectively. Composite of the non-coplanar arcs also reduced maximum dose to the spinal cord by 20-39%. Volume of chest wall receiving higher than 30 Gy was reduced by 48% on average. Heart dose reduction was dependent on the location of the PTV and the choice of non-coplanar orientations. Therefore we conclude that non-coplanar HT arcs significantly improve critical organ sparing in lung SBRT without changing the PTV dose coverage.
KW - Lung
KW - Non-coplanar
KW - Rotational intensity modulated radiation therapy
KW - SBRT
KW - Tomotherapy
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UR - http://www.scopus.com/inward/citedby.url?scp=80053281438&partnerID=8YFLogxK
U2 - 10.7785/tcrt.2012.500207
DO - 10.7785/tcrt.2012.500207
M3 - Article
C2 - 21728387
AN - SCOPUS:80053281438
SN - 1533-0346
VL - 10
SP - 307
EP - 315
JO - Technology in Cancer Research and Treatment
JF - Technology in Cancer Research and Treatment
IS - 4
ER -