Mayur Mayank 25.05.2015
Jul 21, 2015
Mayur Mayank
25.05.2015
ICRU 50
Organs at Risk : These are normal tissues whose radiation sensitivity may significantly influence the treatment planning and/or prescribed dose.
Divided into 3 classes :
1. Class I : Radiation lesions are fatal or result in severe morbidity.
2. Class II : Radiation lesions result in mild to moderate morbidity.
3. Class III : Radiation lesions are mild, transient, and reversible, or result in no significant morbidity.
Brainstem
Temporal lobe
Eyes and lens
Optic Nerves and Optic Chiasm
Pituitary
Temporomandibular Joint
Inner Ear
Middle Ear
Mandible
Parotids
Submandibular glands
Spinal cord
Pharyngeal Constrictors
Brachial Plexus
Cranial Nerves IX-XII
Oesophagus
Thyroid
Good Planning CT Good Immobilization setup
Contrast imaging
3mm slice thickness or smaller
MRI fusion if required
Optimal CT window settings [Centre (HU) and width (HU) values] used to delineate the OARs Brain: C35, W100
Bone: C450, W1,600
H&N: C35, W350
Parotid: C840 , W370
RTOG Contouring guidelines Cranial Nerves IX-XII
Brachial Plexus William H. Hall et al. ; International Journal of Radiation Oncology*Biology*Physics, Volume 72,
Issue 5, 1 December 2008, Pages 1362-1367
Salivary Glands Van de Water et al. ; Radiotherapy and Oncology, Volume 93, Issue 3, December 2009, Pages 545-
552
Swallowing Apparatus Piet Dirix et al. ; International Journal of Radiation Oncology*Biology*Physics, Volume 75, Issue 2,
October 2009, Pages 385-392
Optic Nerves and Chiasm Charles Mayo et al. ; International Journal of Radiation Oncology*Biology*Physics, Volume 76, Issue
3, Supplement, 1 March 2010, Pages S28-S35
Temporal lobe and Ear
Ying Sun et al. ; Radiotherapy and Oncology, Volume 110, Issue 3, March 2014, Pages 390-397
Identify and contour C5, T1, and T2.
Identify and contour the subclavian and axillary neurovascular bundle.
Identify and contour anterior and middle scalene muscles from C5 to insertion onto the first rib.
To contour the brachial plexus OAR use a 5-mm diameter paint tool.
Start at the neural foramina from C5 to T1; this should extend from the lateral aspect of the spinal canal to the small space between the anterior and middle scalene muscles.
For CT slices, where no neural foramen is present, contour only the space between the anterior and middle scalene muscles.
Continue to contour the space between the anterior and middle scalene muscles; eventually the middle scalene will end in the region of the subclavian neurovascular bundle.
Contour the brachial plexus as the posterior aspect of the neurovascular bundle inferiorly and laterally to one to two CT slices below the clavicular head.
The first and second ribs serve as the medial limit of the OAR contour.
IJROBP Vol 72, Dec 2008
Parotid Gland
Lateral : Hypodense area corresponding to subcutaneous fat and more caudally by the platysma.
Medial : Posterior belly of the digastric muscle, the styloid process and the parapharyngeal space.
Cranial : Related to the external auditory canal and mastoid process.
Caudal : Protrudes into the posterior submandibular space inferior to the mandibular angle.
Anterior : Masseter muscle, the posterior border of the mandibular bone and the medial and lateral part of the pterygoid muscle.
Posterior : Anterior belly of the sternocleidomastoid muscle and the lateral side of the posterior belly of the digastric muscle.
The external carotid artery, the retromandibular vein and the extracranial facial nerve are prescribed to be enclosed in the parotid gland
Radiotherapy and Oncology Vol 93, Dec 2009
Radiotherapy and Oncology Vol 110, March 2014
Submandibular Gland
Cranial : Medial pterygoid muscle and the mylohyoid muscle
Caudal : Fatty tissue
Anterior : Lateral surface of the mylohyoid muscle and the hyoglossus muscle
Posterior : Parapharyngeal space and the sternocleidomastoid muscle
Lateral : Medial surface of the medial pterygoid muscle, the medial surface of the mandibular bone and the platysma.
Medial : Lateral surface of the mylohydoid muscle, the hyoglossus muscle, the superior and middle pharyngeal constrictor muscle and the anterior belly of the digastric muscle.
Radiotherapy and Oncology Vol 93, Dec 2009
Radiotherapy and Oncology Vol 110, March 2014
IJROBP Vol 75, Oct 2009
IJROBP Vol 75, Oct 2009
Should be contoured on the Brain window
The lateral boundary of the temporal lobe should be delineated on the soft tissue window
Should include the hippocampus, parahippocampal gyrus and uncus
The basal ganglia and insula are located anteriorly and superiorly to the hippocampus and parahippocampal gyrus and should be excluded
Delineation is better when fused with MRI
Radiotherapy and Oncology Vol 110, March 2014
Middle ear : The tympanic cavity and bony part of the Eustachian Tube (ET) should be contoured individually
The tympanic cavity is delineated
Laterally by the tympanic membrane, defined by the ligature between the two bony structures with an increased density along the anterior and posterior walls of the most medial aspect of the outer air canal
The sharp narrow region connected anteriorly to the ET, and the interface between the temporal bone and air at all other walls
Inner ear : Delineation of the cochlea and Internal Auditory Canal (IAC) should be done individually
The cochlea is located anteriorly to the IAC
Radiotherapy and Oncology Vol 110, March 2014
1: Cochlea (basal turn)
2: Tensor tympani
muscle
3: Manubrium of
malleus
4: Facial nerve canal
5: Stapedius muscle
6: Round window
Radiotherapy and Oncology Vol 110, March 2014
RTOG Contouring atlas
Cranial Nerves IX-XII : http://www.rtog.org/CoreLab/ContouringAtlases/HNAtlases.aspx
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014
Radiotherapy and Oncology Vol 110, March 2014