Page 238 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

P H

VetBooks.ir L R L R

A A B F
Dose [cGy]
0 540 1080 1620 2160 2700 3240 3780 4320 4860 5400 5940
Ratio of total structure volume [%] 100 Left eye
GTV, CTV

A 80 and PTV
60

40

C F 20 Right lens Right eye Skin

0 Left lens
0 10 20 30 40 50 60 70 80 90 100 110
D Relative dose [%]
• Fig. 13.4 A canine nasal tumor with axial (A), dorsal (B), and sagittal (C) sections through a canine nasal
tumor. Dose is in color wash with the prescribed dose in orange. (D) The dose volume histogram. Note the
high dose to the tumor compared with regional normal tissue structures.

TABLE 13.2 Characteristics of Traditionally (Finely) Fractionated Radiation Therapy vs. Stereotactic Radiation
Therapy
General Characteristics 3D/IMRT SRT
Dose/fraction 2.5–4.2 Gy 6–24 Gy
Number of fractions 10–25 1–5
Target definition CTV/PTV gross disease and clinical GTV/CTV/ITP/PTV
extension Well-defined tumors: GTV = CTV
Tumors may not have sharp boundaries
Margins cm mm
Primary imaging modalities for planning CT CT/MR/PET-CT
Redundancy in geometric verification No Yes
Maintenance of high spatial targeting accu- Moderately enforced, moderate patient Strictly enforced (sufficient immobilization and high-
racy for the entire treatment position control and monitoring frequency position monitoring through integrated
image guidance)
Need for respiratory motion management Minimal, usually managed by increas- High particularly for tumors thorax and cranial abdomen
ing ITV
Staff training High High, plus special SRT training
Radiobiologic understanding Well understood Poorly understood
Interaction with systemic therapies Yes; principles well established Yes; minimally understood
Immobilization devices Vac-Lok bags, pillows, and acrylic mesh Vac-Lok bags, pillows, and acrylic mesh + bite blocks
for head and neck tumors
Purpose Palliative/curative Palliative/curative
Modified from Benedict SH, Yenice KM, Followill D, et al. Stereotactic body radiation therapy: the report of AAPM Task Group 101. Med Phys. 2010;37:4078–4101. CT, Computed tomography; CTV, clinical
target volume; GTV, gross tumor volume; IMRT, intensity modulated radiation therapy; ITV, internal target volume; PTV, planning target volume; SRT, stereotactic radiation therapy.
.