Conformal Radiotherapy for Head and Neck Cancer Conformal Radiotherapy in Head and Neck Cancer B. Schicker, U. Götz, I. C. Kiricuta ISRO-Limburg - Germany

Conformal Radiotherapy for Head and Neck Cancer COMPLEX PLANNING TARGET VOLUMES H&N

Conformal Radiotherapy for Head and Neck Cancer Clinical Case: 70-year old patient Diagnosis: Carcinoma of the margin of the tongue, pT1 pN2b M0, tumorgrading G 2-3. Histology: Invasive, medium to low differentiated non cancroids epidermous carcinoma in the area of the rear, left margin of the tongue. Therapy: Status after partial resection of the tongue and a left sided carcinoma of the margin of the tongue (R0 Resection), as well as a conservative neck dissection. Four lymph nodes, infiltrated by the tumor, in the area of the middle and upper parajugular group of lymph nodes on the left. Now: Irradiation with a dose per fraction of 1.8 Gy at a total dose of 50.4 Gy, followed by a boost with 16 Gy to the tumor bed.

Conformal Radiotherapy for Head and Neck Cancer Target Volume Definition in the Case of the Conventional Positioning and Fixation. The target volume contains the body of the tongue, the floor of the mouth, the upper, middle and lower jugular lymph nodes and the supraclavicular lymph nodes. Body of the tongue, floor of the mouth and the upper jugular lymph nodes Middle jugular lymph nodes Lower jugular and supraclavicular lymph nodes

Conformal Radiotherapy for Head and Neck Cancer Target Volume Definition in this Special Patient Localization (Fixation). The CT-slices are 15° declined to the longitudinal body axis (gantry position 0°). Base of the tongue and supraclavicular lymph nodes (Z-4) Floor of the mouth, base of the tongue, middle jugular lymph node group (Z=0) Body of the tongue, jugular lymph nodes (Z+2)

Patient Modell: The figure on the right shows representative CT- slices of the patient model in the room view. The lateral point of view illustrates the atypical positioning of the patient with a 15° inclination on a head rest. Positioning and Fixation of the Patient The special difficulty in this case lies in the distinct vertigo symptom after apoplectic insult, which appears at the patient in supine position, so that he could not be fixed in the standard po- sition (flat supine position, head over stretched, cervical spine as parallel as possible to the couch table). As the only for the patient tolerable and also for the CT possible position a 15° inclined supine position is performed. Conformal Radiotherapy for Head and Neck Cancer

Irradiation Technique The target volume is covered by two rotational fields which are asymmetrically directed over the central beam and two fixed fields from the ventro- lateral direction. All fields are equipped with wedges and individual absorbers to protect the myelon and the healthy tissue. In the regular case the common isocenter of the four fields is positioned in the central beam at the dorsal edge of the spinal cord. In this special case the isocenter has to be moved in the ventral direction because of technical limitations of the irradiation device..

Conformal Radiotherapy for Head and Neck Cancer Physical Treatment Planning The fixed fields from 60° (field 5) resp. 300° (field 4) cover in any direction the whole target volume. In the beam´s eye view the absorbers are set, which protect the healthy tissue. Both fields are normally equipped with the maximum wedge (60° wedge) with the tip in the dorsal direction. Because of the limitations for the field dimensions using wedges - the maximum position of the Y- jaw with a 45° wedge is 12.5 cm, with a 60° wedge only 10.0 cm - in this case compromises have to be made. If the position of the isocenter would kept up, for the ventral Y- jaw a value of 15 cm would be required although only 10 cm are possible. The missing 5 cm can be achieved using a 45° instead of a 60° wedge and with the isocenter moved 2.5 cm in the ventral direction

Conformal Radiotherapy for Head and Neck Cancer Physical Treatment Planning : The fixed fields: - 60° (field 5) resp. 300° (field 4) - cover in any direction the whole target volume - wedge (60° wedge) with the tip in the dorsal direction

Conformal Radiotherapy for Head and Neck Cancer The rotational fields (fields 1 and 2), from 180° to 30° resp. From 330° to 180°, are asymmetrically directed over the central beam. The myelon is at any gantry position out of the primary beam. The inclination of the spinal cord requires a rotation of the collimator, which, in the beam’s eye view, results in a gantry position of 90° resp. 270°. In the cranial part of the myelon a standard absorber is used, whose need and position can also easily be seen in the beam’s eye view. Because the target volume does not range very much dorsal- ward, the covered angle can be shorted in the dorsal area. So the start angle of field 1 is set from 170° to 180°, the stop angle of field 2 corres- pondingly from 190° to 180°

Conformal Radiotherapy for Head and Neck Cancer The rotational fields 1 and 2 from 180° to 30° resp. From 330° to 180° The myelon is at any gantry position out of the primary beam

Conformal Radiotherapy for Head and Neck Cancer Beam Parameter and Beams Eye View for the Basic Technique

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution

Conformal Radiotherapy for Head and Neck Cancer Dose Volume Histogram

Conformal Radiotherapy for Head and Neck Cancer Case II - Complex Technique – Nasopharynx CA

Conformal Radiotherapy for Head and Neck Cancer Target Volume divided in 3 Planning Levels:

Conformal Radiotherapy for Head and Neck Cancer Beams for Level IICase: Non Hodgkin / Floor of the Mouth Beams 1 to 4 from Base Technique

Conformal Radiotherapy for Head and Neck Cancer Beams for Level II & IIICase: CA Floor of the Mouth Beams 1 to 4 from Base Technique plus Field 5 (Supra)

Conformal Radiotherapy for Head and Neck Cancer Beams for Level I, II, IIICase: Nasopharynx CA Beams 1 to 9

Conformal Radiotherapy for Head and Neck Cancer Level II:Field 1 and 2 from the Base Technique Field 1 rotates from 170° to 30° - Field 2 rotates from 330° to 190° Both with a 15° wedge in cranial direction.

Conformal Radiotherapy for Head and Neck Cancer Level II:Beams Eye View / Setup of the Satellite The Myelon is always protecte by the Satellite

Conformal Radiotherapy for Head and Neck Cancer Level II:Dose Distribution of Field 1 and 2 Field 1 and 2 deliver the main dose in the ventral part of the TV

Conformal Radiotherapy for Head and Neck Cancer Level I,II & III:Field 3 and 4 lateral wedge Fields Field 3 and 4 are modified with a 60° wedge (dorsal direction). They cover the entire TV (Level I, II and III)

Conformal Radiotherapy for Head and Neck Cancer Level I,II & III:Beams Eye View / Setup of the Satellite

Conformal Radiotherapy for Head and Neck Cancer Level II:Dose Distribution of Field 3 and 4 Field 3 and 4 deliver the main dose to the dorsal part of the TV. Compensation of the under dosage of field 1&2 in Level II.

Conformal Radiotherapy for Head and Neck Cancer Level III:Field 5 Ventral Field Field 5 cover the ventral part of the TV, modified with a central satellite to protect the myelon.

Conformal Radiotherapy for Head and Neck Cancer Level III: Beams Eye View / Setup of the Satellite

Conformal Radiotherapy for Head and Neck Cancer Level I: Fields 6,7 and 8Box Technique Fields 6 to 8 cover the Nasopharynx, in some cases the lateral fields are modified with a wedge, tip dorsal wards.

Conformal Radiotherapy for Head and Neck Cancer Level I: Beams Eye View / Setup of the Satellite

Conformal Radiotherapy for Head and Neck Cancer Beam parameters of all Fields

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution:

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution:

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution:

Conformal Radiotherapy for Head and Neck Cancer Dose Distribution:

Conformal Radiotherapy for Head and Neck Cancer Dose Volume Histogram

Conformal Radiotherapy for Head and Neck Cancer Thank You Very Much