with the percentage of volume getting 100% and 90% of the dose being62 G 12 and 68 G 12, respectively.Conclusions: Compared to the 3-D volume dose, the prescription pointsoverestimated the dose to the target volume. The underdosing wasbecause of inability of two-channel applicator to compensate in anteriorand posterior dimension. The dose to sigmoid colon was high andattention should be given to the sigmoid dose at the time of treatmentplanning. Correlations with outcome are needed to better define the roleof three-dimensional dosimetry in treatment planning.

P-66

Intraoperative radiotherapy with HDR brachytherapy or electron

beam for advanced gynecologic malignancies

Subir Nag, M.D.,1 Darlene Bugoci1 Chomporn Sitathanee, M.D.,1

Jeffrey Fowler, M.D.,2 Moataz El-Ghamry, M.D.1 1Radiation Medicine,

Ohio State University, Columbus, OH; 2Gynecologic Oncology, Ohio State

University, Columbus, OH.

Purpose: To treat advanced primary or recurrent gynecologic malignanciesusing intraoperative radiotherapy (IORT), intraoperative electron beam(IOERT), or intraoperative high-dose-rate brachytherapy (IOHDR).Methods and Materials: Between March 1992 and March 2005, 35patients with recurrent or locally advanced Gynecologic malignancieswere treated with IORT. Primary sites included: cervix (21); endometrium(5); ovary (4); and others (5). Pathologies included 20 squamous cellcarcinomas, 11 adenocarcinomas, and 4 others. Six were primarymalignancies, and 29 were recurrent. Maximal surgical resection wasattempted in all patients and resulted in completed gross resection in 22patients and partial resection in 13. IORT was performed using IOERT in19 patients, IOHDR in 14, or both in 12. IORT doses ranged from 10 to20 Gy. Additional EBRT was given in 14 patients. The mean followupperiod was 23 months.Results: One patient was lost to followup. Local control was achieved in 13patients (38%). Ten patients were alive and free of disease at last follow-up;2 were alive with disease; 18 died of disease, and 4 died of other causes.Three-year overall survival rate was 39% (median 10 months). Themedian local recurrence-free survival was 7 months. The 3-year localrecurrence-free survival was 30% (48% for those with microscopicresidual disease versus 8% with gross residual disease, p 5 0.01). A trendtoward improved overall survival was noted for microscopic residualdisease (p 5 0.14), although it was not statistically significant. Nosignificant difference in survival was observed between IOERT andIODHR (p 5 0.8). Morbidity included pelvic abscess (n 5 13),neuropathy (12), thromboembolism (5), fistula (5) enteritis (4), fecalincontinence (1), and small bowel obstruction (1).Conclusions: Patients with recurrent or locally advanced Gynecologicmalignancies have a poor prognosis and limited treatment options. Thecombination of maximal surgical resection and IORT offers a chance atimproved local control and overall survival, especially if gross resectioncan be achieved.

P-67

ICRU points significantly underestimate the bladder and rectal dose

delivered by high-dose-rate brachytherapy for cervical cancer

Shalin Shah, M.D.,1,2 Rajiv Sharma, M.D.,1,2 Ravi Yaparpalvi, M.S.,1,2

Madhur Garg, M.D.,1,2 Shalom Kalniciki, M.D.,1,2 Subhakar Mutyala,

M.D.1,2 1Radiation Oncology, Montefiore Medical Center, Bronx, NY;2Radiation Oncology, Albert Einstein College of Medicine, Bronx, NY.

Purpose: The International Commission on Radiation Units andMeasurements (ICRU) points have been used to estimate the dosedelivered to the bladder and rectum during brachytherapy treatment forcervical cancer. With CT-based 3D conformal planning and CTcompatible applicators, true dose volume histograms (DVH) can beachieved. We compared the dose given to the ICRU bladder and rectumpoints with the DVHs of patients treated with high-dose-ratebrachytherapy for cervical cancer to see the relationship and determinewhich is preferable.

Methods and Materials: Between July 2004 and November 2005, patientswere enrolled in a prospective trial comparing the dosages delivered to theICRU bladder and rectum points with the corresponding CT based DVHs.All patients were implanted using the Nucletron CT/MR compatibleFletcher-Suit Tandem and Colpostat applicators. After the implant wasperformed and proper positioning ensured, the patients underwent a CTscan for planning purposes. On the planning scan, the entire bladder wascontoured and the rectum was contoured from the anus to the sigmoidflexure. A high dose rate plan was created using Nucletron PLATOsoftware. The ICRU points for bladder and rectum (using ICRU 38definitions), along with the DVH values for 0.5, 2, 5 and 10 cm3 volumeswere generated and recorded for each patient. All patients subsequentlyreceived high-dose-rate (HDR) treatment with the NucletronMicroselectron.Results: A total of 23 individual CT scans were obtained and evaluated forthe study. For the bladder, the ICRU point mean dose was 59% ofprescription (range 33–91). The mean doses for 0.5, 2, 5, and 10 cm3

were 99% (61–145), 84% (54–99), 72% (49–78), and 61% (43–68),respectively. The mean ICRU bladder point dose was significantly lowerthan all the measured DVH volumes (p!0.05), with the exception of the10cm3 volume (p 5 0.75). For the rectum, the ICRU point mean dose was48% of prescription (28–81). The mean doses for 0.5, 2.5, and 10 cm3

were 75% (53–91), 64% (40–79), 55% (32–69), and 48% (27–58),respectively. Again, the mean ICRU rectum point dose was significantlylower than all measured DVH volumes (p!0.05), with the exception ofthe 10 cm3 volume (p 5 0.76).Conclusions: We have shown that dose calculations using ICRU definedbladder and rectum points significantly underestimate the actual dosedelivered, as measured by CT based DVHs. We recommend that all HDRprocedures for cervical cancer employ CT compatible applicators toobtain true bladder and rectum DVHs. Longer term followup is needed tocorrelate delivered dosages with late toxicity.

100 Abstracts / Brachytherapy 5 (2006) 78–117

P-68

HI-ART tomotherapy megavoltage CT-based cumulative dose

volume histograms and isodose curve plans for low-dose-rate

brachytherapy of cervical cancer

Jessamy A Boyd, M.D., David L Wilson, M.S., William J Spanos, M.D.,

Catheryn M Yashar, M.D. Radiation Oncology, University of Louisville,

Louisville, KY.

Purpose: Evaluation of HiArt tomotherapy megavoltage CT imaging todetermine cumulative dose volume histograms (DVH) and cumulativeisodose cure plans for intracavitary low-dose-rate brachytherapy ofcervical carcinoma. Megavoltage scanning reduces artifact from metalapplicator sets and allows for accurate contouring of anatomic structures.Doses from the cumulative DVHs were compared with the ICRU 50bladder and rectal points and Point A doses.Methods and Materials: Five patients underwent external beamradiation therapy and low-dose-rate (LDR) brachytherapy for cervicalcarcinoma. A pelvic CT scan was obtained for external beam treatmentplanning. The bladder, rectum, vagina, cervix, and uterus werecontoured. Patients had LDR tandem and ovoid implants placed usingstandard Fletcher-Suit applicators followed by a megavoltage CT. Thesame anatomic areas were contoured on the megavoltage CTs. An in-house computer program was written to import tomotherapy data intoADAC treatment planning software. External beam and brachytherapyCTs were fused to develop cumulative isodose curves and DVHs,which were compared with Point A and bladder and rectal does pointsplaced according to ICRU guidelines.Results: The ICRU 50 bladder point does generally underestimates bladderdoes compared to the maximum bladder does and maximum contiguous 1,2, and 5 cm3 bladder wall doses (mean and median variation of 28.72 and20.78 Gy, respectively). ICRU 50 rectal point does also underestimateddoes when compared with doses calculated suing 3D techniques, but weremore accurate. Man and median variation from the maximum rectal doesand maximum contiguous 1, 2, and 5 cm3 rectal doses were 12.11 and8.44 Gy. Point A doses varied from doses delivered to 100%, 95%, and

Purpose: HDR brachytherapy is proven effective in the treatment of certaintypes of gynecological cancers. To ensure accuracy in dose delivery, it isrecommended to have an independent method of treatment timecalculation. Not much information is readily available to double checkpatient treatment times calculated by the treatment planning systems fortandem and ring applicators. Spanning three years and 110 separatetreatments for tandem and ring HDR applicators, we present our data andprovide factors to verify treatment times.Methods and materials: Tandems of zero and 60 mm length and rings ofdiameters 26 mm, 30 mm and 34 mm were used. The study involved 15,

101Abstracts / Brachytherapy 5 (2006) 78–117

90% of the cervix and overestimated dose. Mean and median variation was10.86 and 11.62 Gy.Conclusions: Tomotherapy megavoltage CT brachytherapy imaging allowsfor the generation of cumulative DVHs to evaluate normal tissue and targettissue doses without CT-compatible applicators. Megavoltage CT allows foraccurate delineation of structures by eliminating metallic artifact. ICRUbladder and rectal points underestimate the does received by the bladderand rectum when 3D imaging techniques are used to calculated dose.Point A doses overestimate cervical dose.

P-69

3D dosimetric comparison of two CT-compatible applicators:

Tandem and ring and tandem and ovoids applicator

I-Chow J Hsu, M.D., Yongbok Kim, Ph.D., Albert Chan, C.M.D., R.T.T.,

Jean Pouliot, Ph.D. Radiation Oncology, University of California San

Francisco, San Francisco, CA.

Purpose: Tandem and Ring (R) and Tandem and Ovoids (O) have differentdwell position. We paravaginal tissue and dwell time optimization.Methods and Materials: We applied a latex condom and contrast soakedpacking around Nucletron CT compatible applicator to simulate theapplicator in situ. We positioned the R applicator on so the ring is parallelto the CT slices. Similarly, we positioned the O applicator so the axes ofovoids are parallel to the CT slices. We scanned each applicator witha 6 cm tandem using 3-mm thick slices and digitized the images using theNucletron Plato treatment planning systems. We measured the distancesbetween point A (Pt A) and all the dwell positions in the ring and avoids.We measured the cross section dimensions of each applicator with andwithout packing at the level of the dwell positions. We contoureda paravaginal volume with an inner surface the shape of the applicatorswith and without vaginal packing. Only the intrauterine (IU) dwellpositions and 10 (5 on each side) intravaginal (IV) dwell positions wereturn on. After prescribing dose to Pt A and Pt A0 (5 mm lateral), wecalculated dose volume histogram (DVH) of the paravaginal tissue. Wemade additional comparisons of the DVH using different weightingbetween the applicators.Results: The average distance between Pt A and dwell positions in the Rwas 4.9 mm shorter than the O (35.4 mm, 40.3 mm, respectively). Thecross section dimension for O and R without packing were 48� 30 mm,42� 40 mm, and with packing were 51� 43 mm, 43� 47 mm,respectively. With 1:1 (IU:IV) dwell weighting, normalized to Pt A, theV125-vagina for O and R were 7 and 8 cm3; V150-vagina were 2 and 5 cm3,respectively. With 0.75:1 weighting the V125-vagina for O and R were 11and 11 cm3; V150-vagina were 5 and 7 cm3, respectively. With 0.75:1weighting but prescribed to Pt A0, then V125-vagina O and R were 23 and19 cm3; V150-vagina 14, and 13 cm3, respectively. Vaginal packingdecreased the high does volume. With 0.75:1 weighting, prescribed to PtA0, with packing V125-vagina O and R were 18 and 20 cm3, V 150-vagina 9and 13 cm3. The V100-implant for O and R were 113 and 105 cm3 with 1:1weighting and normalized to Pt A.Conclusions: Dwell positions in the ring applicator are closer to point A butthey are also closer to the vaginal surface. This increases the vagina volumereceiving higher does (O125%) from the ring applicator vs. the ovoidapplicator. However, when treating points beyond Pt A, the rate ofincrease is less for the ring applicator. The packing was more effectivedecreasing high dose volume for the ovoids. We plan to test additionalapplicator combinations.

P-70

Verification of treatment times for tandem and ring HDR

brachytherapy

Pushkar T Daesi, M.S., Cindy Parry, M.S., Max D’Souza, Ph.D., George

Thomas, M.S., Clinton Medbery III, M.D., Astrid Morrison, M.D.,

Marianne Young, M.D. Radiation Oncology, Frank C Love Cancer

Institute, St. Anthony Hospital, Oklahoma City, OK.

30, 45, and 60 degree angle applicators for the 60 mm length tandem. Averification factor using the total number of dwell positions, totaltreatment time, activity of source, and prescribed dose was computed foreach treatment. The data were grouped based on tandem lengths and anaverage verification factor was computed. This factor was then used tocalculate the treatment times for the sample set.Results: The average verification factor for a zero length tandem is 0.149with a standard deviation of 4.2% for 36 patient treatments while that fora 60 mm tandem is 0.274 with a standard deviation of 5.2% for 74patients. The accuracy of the verification factor for predicting totaltreatment time is within 5.6% for the zero length tandem and within 10%for the 60 mm tandem.Conclusions: The verification factors for these applicators can be used tocheck patient treatment times independently calculated by the treatmentplanning system within 10%.

P-71

Retrospective evaluation of single treatment plan per course vs plan

per fraction for high-dose-rate vaginal cylinders

Earl Nixon, B.Eng., Joseph M Modrick, Ph.D., Geraldine M Jacobson,

M.D. Radiation Oncology, University of Iowa, Iowa City, IA.

Purpose: A retrospective analysis of brachytherapy treatment planning ispresented. Patients with endometrial cancer were treated by hysterectomyand adjuvant HDR brachytherapy in three fractions to the vaginal cuffusing fixed geometry cylindrical applicators. Dose optimization based onorthogonal radiographs were performed. Treatment planning for eachfraction (plan A) was compared to one treatment plan for all threefractions (plan B). The intent was to demonstrate that a single treatmentplan for each fraction was comparable to planning each fractionindividually. Possible benefits of plan B include cost and time savingswithout sacrificing treatment integrity.Methods and Materials: Twenty patients with stage I endometrial cancerwere prescribed 15 GyHDR Brachytherapy to the vaginal cuff viaa vaginal cylinder in three weekly fractions. Dose was prescribed ata distance of 5 mm from the cylinder applicator surface. A foley catheterwith radiopaque contrast was placed in the bladder and a rubber tubeplaced in the rectum for critical soft tissue delineation. Two orthogonalradiographs were obtained for each fraction and used for dose and dwelltime calculations in the BrachyVision treatment planning system. A Ir-192 remote afterloader (Varisoure) was used to deliver the treatment. Thesummation of treatment plans for each fraction (plan A) was compared tothe summation of the first treatment plan as the only plan for all threefractions (plan B). The total dose to the prescription point, the sum ofmaximum point dose for each fraction to the bladder, the sum ofmaximum point dose for each fraction to the rectum, the percentage ofprescribed dose to the bladder and the percentage of prescribed dose tothe rectum were analyzed for each treatment method.Results: Total dose to the 5 mm prescription point for plan A and plan B was14.83 G 3 Gy. Maximum dose to the bladder for Plan A was11.51 G 2.64 Gy and for plan B 12.27 G 3.17 Gy. Percentage ofprescribed dose to the bladder for plan A was 76 G 17% and 81 G 21%for plan B. Maximum dose to the rectum for plan A was 13.15 G 2 Gyand for plan B 13.69 G 2.43 Gy. Percentage of prescribed dose to therectum for plan A was 87 G 13% and 91 G 16% for plan B.Conclusions: The prescription dose for both treatment plans wasequivalent. The maximum dose to the balder and rectum for each planwas well within one standard deviation. The average percentage ofprescribed dose for each plan was within about 5% for the bladder and