Dosimetric comparison of bone marrow-sparing intensity-modulated radiotherapy versus conventional techniques for treatment of cervical cancer.
OBJECTIVE
To compare bone marrow-sparing intensity-modulated pelvic radiotherapy (BMS-IMRT) with conventional (four-field box and anteroposterior-posteroanterior [AP-PA]) techniques in the treatment of cervical cancer.


METHODS
The data from 7 cervical cancer patients treated with concurrent chemotherapy and IMRT without BMS were analyzed and compared with data using four-field box and AP-PA techniques. All plans were normalized to cover the planning target volume with the 99% isodose line. The clinical target volume consisted of the pelvic and presacral lymph nodes, uterus and cervix, upper vagina, and parametrial tissue. Normal tissues included bowel, bladder, and pelvic bone marrow (PBM), which comprised the lumbosacral spine and ilium and the ischium, pubis, and proximal femora (lower pelvis bone marrow). Dose-volume histograms for the planning target volume and normal tissues were compared for BMS-IMRT vs. four-field box and AP-PA plans.


RESULTS
BMS-IMRT was superior to the four-field box technique in reducing the dose to the PBM, small bowel, rectum, and bladder. Compared with AP-PA plans, BMS-IMRT reduced the PBM volume receiving a dose >16.4 Gy. BMS-IMRT reduced the volume of ilium, lower pelvis bone marrow, and bowel receiving a dose >27.7, >18.7, and >21.1 Gy, respectively, but increased dose below these thresholds compared with the AP-PA plans. BMS-IMRT reduced the volume of lumbosacral spine bone marrow, rectum, small bowel, and bladder at all dose levels in all 7 patients.


CONCLUSIONS
BMS-IMRT reduced irradiation of PBM compared with the four-field box technique. Compared with the AP-PA technique, BMS-IMRT reduced lumbosacral spine bone marrow irradiation and reduced the volume of PBM irradiated to high doses. Therefore BMS-IMRT might reduce acute hematologic toxicity compared with conventional techniques.
Mell
Loren K
LK
Department of Radiation Oncology, School of Medicine, University of California-San Diego, La Jolla, CA, USA.
Tiryaki
Hanifi
H
Ahn
Kang-Hyun
KH
Mundt
Arno J
AJ
Roeske
John C
JC
Aydogan
Bulent
B
D000328:Adult; D000368:Aged; D001853:Bone Marrow / Q000528:radiation effects*; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D007421:Intestine, Small; D008875:Middle Aged; D010384:Pelvic Bones / Q000528:radiation effects*; D011835:Radiation Protection; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum; D001743:Urinary Bladder; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*