Esophageal Adenocarcinoma Methods and Protocols

13

if intensity modulated radiotherapy (IMRT) or breath holding/

IGRT is employed.

The lungs, heart, spinal cord, liver, and kidneys should be con-

toured in their entirety in the planning CT. The dose volume con-

straints of OARs for radiotherapy planning are as shown in Table 1

[ 11 , 12 ]. Heterogeneity corrections should be used in the final

dose calculation for dose to the lung tissues. Effort should be made

to minimize the dose to the lungs and to the heart, especially the left

ventricle. For 3DCRT, beam arrangements that avoid OARs should

be chosen. The fractional dose to the lungs, heart, and spinal cord

should be maintained at 2 Gy or less per fraction. Figure 1 shows

3.4 Organs
at Risk (OARs)

Table 1

Dosimetric limits for OARs (organs at risk) (not to be exceeded

in planning of radiotherapy)

Organ Dose limits Toxicity endpoint

Total lung V5 ≤ 65%

V20 ≤ 25%

Mean dose ≤ 20 Gy

Grade ≥ 2 radiation

pneumonitis

Spinal cord Dmax ≤ 45 Gy Myelitis

Heart 1/3

2/3

3/3

≤ 50 Gy

≤ 45 Gy

≤ 40 Gy

Clinical pericarditis

Liver 60% ≤ 30 Gy Clinical hepatitis

Kidney 2/3 of one kidney ≤ 20 Gy Renal insufficiency

V5: volume of organ receiving 5 Gy, V20: volume of organ receiving 20 Gy. A larger

volume of organ irradiated will tolerate less dose

Dmax: maximum dose to organ

Fig. 1 Coronal and transaxial view of a patient with distal esophageal cancer planned for neoadjuvant chemo-
radiotherapy showing the gross tumor volume—GTV(magenta), planning target volume—PTV (red), and organs
at risk [lungs (green) and liver (brown)]

Radiotherapy