Maximum dose to the organs at risk (including organs immediately adjacent to the tumor).

<p>Std. Dev.: standard deviation. Central: central lesions for which all the dose constraints were met. Central_no: central lesions for which ≥1 dose constraints were not met. Peripheral: peripheral lesions. Gy: gray.</p

Comparison of the tumor characteristics of the Central_no group of lesions with the Central and Peripheral groups of lesions.

<p>Central+Peripheral: central and peripheral lesions for which all the dose constraints were met. Central_no: central lesions for which ≥1 dose constraints were not met. Std. dev.: standard deviation. GTV: gross tumor volume. PTC: planning target volume. #: number. cm: centimeter. cc: cubic centimeter. OARs: organs at risk.</p

Dose parameters for the normal lung tissue.

<p>Std. Dev.: standard deviation. Central: central lesions for which all the dose constraints were met. Central_no: central lesions for which ≥1 dose constraints were not met. Peripheral: peripheral lesions. V₅, V₁₀, and V₂₀: percentage of volume receiving 5, 10, and 20 Gy, respectively. MLD: mean lung dose.</p

Dose Coverage of the PTV for the three groups of lung lesions.

<p>PTV: planning target volume. OARs: Organs at risk. D₉₅: dose covering 95% of the PTV; %PTV_{70 Gy}: percentage of the PTV volume receiving 70 Gy; PTV_max: maximum dose to the PTV. Std. Dev.: standard deviation; Central: central lesions for which all the dose constraints were met; Central_no: central lesions for which ≥1 dose constraints were not met; Peripheral: peripheral lesions.</p

Grade 5 toxicity reported in the literature following stereotactic body radiotherapy for centrally located lung cancer.

†<p>Fr: fractions;</p>*<p>previously irradiated patients.</p

Dose constraints for the prescription dose of 70 Gy delivered in 10 fractions.

*<p>30 Gy acceptable in selected cases.</p>†<p>Total lung volume = total volume of both lungs minus that of the GTV.</p><p>V₂₀ is the % of the volume receiving 20 Gy. MLD: mean lung dose.</p

Comparison of dose parameters to the organs at risk.

<p>Organs at risk: a) Esophagus, b) heart, c) major airway, d) major vessels, e) spinal cord, f) and g) mean lung dose (MLD) and V₂₀ for the total lung, after normalized to the absolute dose constraints between helical tomotherapy (Tomo), 2-arc, and 8-arc VMAT plans.</p

Illustration of the possible scenarios of dose conformity described by the conformation number (CN).

<p>The shade represents the target volume, the dotted line represents the desired isodose, the small solid in c) represent a critical structure that is immediately adjacent to the target. a). the ideal dose conformation with CN = 1. b). Less than optimal coverage of the target volume. c). In situations where the target is next to a critical structure, both adequate dose coverage of the target and the sparing of the critical structure are desired. As a result, more healthy tissue is irradiated in the context of the healthy tissue dose constraint as shown. The CN will be <1 is both b) and c).</p

Comparison of the maximum dose other organs at risk (OARs) generated through helical tomotherapy, VMAT with 2 arcs, and 8 arcs with absolute doses illustrated in mean ± standard deviation.

<p>Comparison of the maximum dose other organs at risk (OARs) generated through helical tomotherapy, VMAT with 2 arcs, and 8 arcs with absolute doses illustrated in mean ± standard deviation.</p

Illustration of a comparison of the 2 and 8 Arc plans demonstrating that the shape of the isodose covering the PTV is largely dependent on the immediately adjacent critical structures (yellow and blue) that need to be spared in one patient.

<p>As a result, slightly increased volume of the normal lung tissue is included in the high dose volume lateral to the PTV (blue shade) away from the central structures. Also shown here is that when comparing to the 2 Arc plan, the high dose region included by the 77 Gy isodose in the 8 Arc plan is greatly diminished, demonstrating increased homogeneity.</p