On the performances of different IMRT Treatment Planning Systems for selected paediatric cases.
BACKGROUND
To evaluate the performance of seven different TPS (Treatment Planning Systems: Corvus, Eclipse, Hyperion, KonRad, Oncentra Masterplan, Pinnacle and PrecisePLAN) when intensity modulated (IMRT) plans are designed for paediatric tumours.


METHODS
Datasets (CT images and volumes of interest) of four patients were used to design IMRT plans. The tumour types were: one extraosseous, intrathoracic Ewing Sarcoma; one mediastinal Rhabdomyosarcoma; one metastatic Rhabdomyosarcoma of the anus; one Wilm's tumour of the left kidney with multiple liver metastases. Prescribed doses ranged from 18 to 54.4 Gy. To minimise variability, the same beam geometry and clinical goals were imposed on all systems for every patient. Results were analysed in terms of dose distributions and dose volume histograms.


RESULTS
For all patients, IMRT plans lead to acceptable treatments in terms of conformal avoidance since most of the dose objectives for Organs At Risk (OARs) were met, and the Conformity Index (averaged over all TPS and patients) ranged from 1.14 to 1.58 on primary target volumes and from 1.07 to 1.37 on boost volumes. The healthy tissue involvement was measured in terms of several parameters, and the average mean dose ranged from 4.6 to 13.7 Gy. A global scoring method was developed to evaluate plans according to their degree of success in meeting dose objectives (lower scores are better than higher ones). For OARs the range of scores was between 0.75 +/- 0.15 (Eclipse) to 0.92 +/- 0.18 (Pinnacle(3) with physical optimisation). For target volumes, the score ranged from 0.05 +/- 0.05 (Pinnacle(3) with physical optimisation) to 0.16 +/- 0.07 (Corvus).


CONCLUSIONS
A set of complex paediatric cases presented a variety of individual treatment planning challenges. Despite the large spread of results, inverse planning systems offer promising results for IMRT delivery, hence widening the treatment strategies for this very sensitive class of patients.
Fogliata
Antonella
A
Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona, Switzerland. afc@iosi.ch
Nicolini
Giorgia
G
Alber
Markus
M
Asell
Mats
M
Clivio
Alessandro
A
Dobler
Barbara
B
Larsson
Malin
M
Lohr
Frank
F
Lorenz
Friedlieb
F
Muzik
Jan
J
Polednik
Martin
M
Vanetti
Eugenio
E
Wolff
Dirk
D
Wyttenbach
Rolf
R
Cozzi
Luca
L
D000293:Adolescent; D002648:Child; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000532:radiotherapy; D008297:Male; D008495:Medical Oncology / Q000379:methods; D010372:Pediatrics / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012208:Rhabdomyosarcoma / Q000532:radiotherapy; D012512:Sarcoma, Ewing / Q000532:radiotherapy; D013899:Thoracic Neoplasms / Q000532:radiotherapy; D014057:Tomography, X-Ray Computed / Q000379:methods; D009396:Wilms Tumor / Q000532:radiotherapy