Evaluation of therapeutic potential of heavy ion therapy for patients with locally advanced prostate cancer.
OBJECTIVE
To investigate the feasibility of raster scanned heavy charged particle therapy in the treatment of prostate cancer (PCa,) with special regard to the influence of internal organ motion on the dose distribution.


METHODS
The CT data of 8 patients with PCa who underwent three-dimensional conformal radiotherapy (RT) were chosen. In addition to the routine treatment planning scan, three to five additional positioning control CT scans were performed. The organs at risk and the target volumes were defined on all CT scans. Primary and boost carbon ion plans were calculated to deliver 66 Gy to the clinical target volume/planning target volume, with an additional 10 Gy to the gross tumor volume (GTV). To estimate the influence of internal organ motion on plan quality, the dose was recalculated on the basis of the control CT scans. The comparative analysis was based on the dose-volume histogram-derived physical parameters.


RESULTS
The average 90% target coverage was 99.1% for the GTV. The maximal dose to the rectum was 71.8 Gy. The average rectal mean dose was 19 Gy. The volume of the rectum receiving 70 and 68 Gy was 0.1 and 0.3 cm3. The average difference in the 90% coverage for the GTV on control CT cubes was 3.6%. The maximal rectal dose increased to 76.2 Gy. The deviation in the mean rectal dose was <1 Gy on average. The rectal volume receiving 70 and 68 Gy increased to 2.5 and 3.3 cm3.


CONCLUSIONS
The investigation demonstrated the feasibility of raster scanned carbon ions for PCa RT. Excellent coverage of the target volume and optimal sparing of the rectum were acquired. The combination of photon intensity-modulated RT and a carbon ion boost to the GTV is the most rational solution for the gain of clinical experience in heavy ion RT for PCa patients.
Nikoghosyan
Anna
A
Division of Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. a.nikoghosyan@dkfz.de
Schulz-Ertner
Daniela
D
Didinger
Bernd
B
Jäkel
Oliver
O
Zuna
Ivan
I
Höss
Angelika
A
Wannenmacher
Michael
M
Debus
Jürgen
J
D002244:Carbon / Q000627:therapeutic use*; D005240:Feasibility Studies; D005270:Femur Head; D063193:Heavy Ion Radiotherapy; D006801:Humans; D008297:Male; D009068:Movement; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D012007:Rectum; D001743:Urinary Bladder
D002244:Carbon