G. Dipasquale

[(18)F]Fluoroethyltyrosine- positron emission tomography-guided radiotherapy for high-grade glioma.

BackgroundTo compare morphological gross tumor volumes (GTVs), defined as pre- and postoperative gadolinium enhancement on T1-weighted magnetic resonance imaging to biological tumor volumes (BTVs), defined by the uptake of 18F fluoroethyltyrosine (FET) for the radiotherapy planning of high-grade glioma, using a dedicated positron emission tomography (PET)-CT scanner equipped with three triangulation lasers for patient positioning.MethodsNineteen patients with malignant glioma were included into a prospective protocol using FET PET-CT for radiotherapy planning. To be eligible, patients had to present with residual disease after surgery. Planning was performed using the clinical target volume (CTV = GTV ∪ BTV) and planning target volume (PTV = CTV + 20 mm). First, the interrater reliability for BTV delineation was assessed among three observers. Second, the BTV and GTV were quantified and compared. Finally, the geometrical relationships between GTV and BTV were assessed.ResultsInterrater agreement for BTV delineation was excellent (intraclass correlation coefficient 0.9). Although, BTVs and GTVs were not significantly different (p = 0.9), CTVs (mean 57.8 ± 30.4 cm3) were significantly larger than BTVs (mean 42.1 ± 24.4 cm3; p < 0.01) or GTVs (mean 38.7 ± 25.7 cm3; p < 0.01). In 13 (68%) and 6 (32%) of 19 patients, FET uptake extended ≥ 10 and 20 mm from the margin of the gadolinium enhancement.ConclusionUsing FET, the interrater reliability had excellent agreement for BTV delineation. With FET PET-CT planning, the size and geometrical location of GTVs and BTVs differed in a majority of patients.

Involved-node and involved-field volumetric modulated arc vs. fixed beam intensity-modulated radiotherapy for female patients with early-stage supra-diaphragmatic Hodgkin lymphoma: a comparative planning study

PURPOSE A comparative treatment planning study was performed to compare volumetric-modulated arc (RA) to conventional intensity modulated (IMRT) for involved-field (IFRT) and involved-node (INRT) radiotherapy for Hodgkin lymphoma (HL). METHODS AND MATERIALS Plans for 10 early-stage HL female patients were computed for RA and IMRT. First, the planning target volume (PTV) coverage and organs at risk (OAR) dose deposition was assessed between the two modalities. Second, the OAR (lung, breast, heart, thyroid, and submandibular gland) dose-volume histograms were computed and compared for IFRT and INRT, respectively. RESULTS For IFRT and INRT, PTV coverage was equally homogeneous with both RA and IMRT. By and large, the OAR irradiation with IFRT planning was not significantly different between RA and IMRT. For INRT, doses computed for RA were, however, usually lower than those with IMRT, particularly so for the lung, breast, and thyroid. Regardless of RA and IMRT modalities, a significant 20-50% decrease of the OAR computed mean doses was observed with INRT when compared with IFRT (Breast D(Mean) 1.5 +/- 1.1 vs. 2.6 +/- 1.7 Gy, p < 0.01 and 1.6 +/- 1.1 vs. 2.9 +/- 1.9 Gy, p < 0.01 for RA and IMRT, respectively). CONCLUSIONS RA and IMRT results in similar level of dose homogeneity. With INRT but not IFRT planning, the computed doses to the PTV and OAR were usually higher and lower with RA when compared to IMRT. Regardless of the treatment modality, INRT when compared with IFRT planning led to a significant decrease in OAR doses, particularly so for the breast and heart.

RapidArc, intensity modulated photon and proton techniques for recurrent prostate cancer in previously irradiated patients: a treatment planning comparison study

BackgroundA study was performed comparing volumetric modulated arcs (RA) and intensity modulation (with photons, IMRT, or protons, IMPT) radiation therapy (RT) for patients with recurrent prostate cancer after RT.MethodsPlans for RA, IMRT and IMPT were optimized for 7 patients. Prescribed dose was 56 Gy in 14 fractions. The recurrent gross tumor volume (GTV) was defined on 18F-fluorocholine PET/CT scans. Plans aimed to cover at least 95% of the planning target volume with a dose > 50.4 Gy. A maximum dose (DMax) of 61.6 Gy was allowed to 5% of the GTV. For the urethra, DMax was constrained to 37 Gy. Rectal DMedian was < 17 Gy. Results were analyzed using Dose-Volume Histogram and conformity index (CI90) parameters.ResultsTumor coverage (GTV and PTV) was improved with RA (V95% 92.6 ± 7.9 and 83.7 ± 3.3%), when compared to IMRT (V95% 88.6 ± 10.8 and 77.2 ± 2.2%). The corresponding values for IMPT were intermediate for the GTV (V95% 88.9 ± 10.5%) and better for the PTV (V95%85.6 ± 5.0%). The percentages of rectal and urethral volumes receiving intermediate doses (35 Gy) were significantly decreased with RA (5.1 ± 3.0 and 38.0 ± 25.3%) and IMPT (3.9 ± 2.7 and 25.1 ± 21.1%), when compared to IMRT (9.8 ± 5.3 and 60.7 ± 41.7%). CI90 was 1.3 ± 0.1 for photons and 1.6 ± 0.2 for protons. Integral Dose was 1.1 ± 0.5 Gy*cm3 *105 for IMPT and about a factor three higher for all photons techniques.ConclusionRA and IMPT showed improvements in conformal avoidance relative to fixed beam IMRT for 7 patients with recurrent prostate cancer. IMPT showed further sparing of organs at risk.

Hypofractionated Boost With High-Dose-Rate Brachytherapy and Open Magnetic Resonance Imaging–Guided Implants for Locally Aggressive Prostate Cancer: A Sequential Dose-Escalation Pilot Study

PURPOSE To evaluate the feasibility, tolerance, and preliminary outcome of an open MRI-guided prostate partial-volume high-dose-rate brachytherapy (HDR-BT) schedule in a group of selected patients with nonmetastatic, locally aggressive prostatic tumors. METHODS AND MATERIALS After conventional fractionated three-dimensional conformal external radiotherapy to 64-64.4 Gy, 77 patients with nonmetastatic, locally aggressive (e.g., perineural invasion and/or Gleason score 8-10) prostate cancer were treated from June 2000 to August 2004, with HDR-BT using temporary open MRI-guided (192)Ir implants, to escalate the dose in the boost region. Nineteen, 21, and 37 patients were sequentially treated with 2 fractions of 6 Gy, 7 Gy, and 8 Gy each, respectively. Neoadjuvant androgen deprivation was given to 62 patients for 6-24 months. Acute and late toxicity were scored according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scoring system. RESULTS All 77 patients completed treatment as planned. Only 2 patients presented with Grade > or =3 acute urinary toxicity. The 3-year probability of Grade > or =2 late urinary and low gastrointestinal toxicity-free survival was 91.4% +/- 3.4% and 94.4% +/- 2.7%, respectively. Rates of 3-year biochemical disease-free survival (bDFS) and disease-specific survival were 87.1% +/- 4.1% and 100%, respectively. CONCLUSIONS Boosting a partial volume of the prostate with hypofractionated HDR-BT for aggressive prostate cancer was feasible and showed limited long-term toxicity, which compared favorably with other dose-escalation methods in the literature. Preliminary bDFS was encouraging if one considers the negatively selected population of high-risk patients in this study.

Cranio-spinal irradiation with volumetric modulated arc therapy: A multi-institutional treatment experience

PURPOSE To report the treatment of cranio-spinal irradiation (CSI) with volumetric modulated arc therapy (RapidArc) in adults and a child. MATERIALS AND METHODS Five patients from 5 institutions were treated with CSI using RapidArc technology. Patient age varied between 7 and 45 years. The lengths of the planning target volumes (PTV) and dose prescriptions ranged from 54.6 to 78.4 cm, and from 12 to 36 Gy, respectively. Different arc arrangements were used, with two or three isocentres, from two to six modulated arcs, for patient positioned either in prone (n=3) or supine position (n=2). Doses to PTV, organs at risk and non-target tissue are reported for each of the five patients. Data concerning imaging strategy and pre-treatment quality assurance are also reported. RESULTS The mean conformity index CI(95%) was 1.05 ± 0.05 (range: 1.00, 1.13). Mean doses to the lenses, lungs, heart, and kidneys were, respectively, 7.6 ± 1.6, 6.6 ± 3.0, 5.7 ± 2.3, and 6.1 ± 2.1 Gy, keeping those value acceptably low. Mean non-target tissue dose was 21.0 ± 3.8% (5.6 ± 1.8 Gy, range: 3.0-8.1 Gy). All patients were successfully planned and treated with RapidArc. CONCLUSIONS RapidArc techniques achieved highly conformal treatment plans for 5 adults or paediatric patients. Beam-on time was short, and RapidArc plans were satisfactorily delivered to all presented patients.

Recurrence pattern after ((18)F)Fluoroethyltyrosine-Positron Emission Tomography-guided radiotherapy for high-grade glioma: A prospective study

PURPOSE To assess the failure pattern observed after (18)F fluoroethyltyrosine (FET) planning after chemo- and radiotherapy (RT) for high-grade glioma. METHODS All patients underwent prospectively RT planning using morphological gross tumour volumes (GTVs) and biological tumour volumes (BTVs). The post-treatment recurrence tumour volumes (RTVs) of 10 patients were transferred on their CT planning. First, failure patterns were defined in terms of percentage of RTV located outside the GTV and BTV. Second, the location of the RTV with respect to the delivered dose distribution was assessed using the RTVs DVHs. Recurrences with >95% of their volume within 95% isodose line were considered as central recurrences. Finally, the relationship between survival and GTV/BTV mismatches was assessed. RESULTS The median percentages of RTV outside the GTV and BTV were 41.8% (range, 10.5-92.4) and 62.8% (range, 34.2-81.1), respectively. The majority of recurrences (90%) were centrally located. Using a composite target volume planning formalism, the degree of GTV and BTV mismatch did not correlate with survivorship. CONCLUSIONS The observed failure pattern after FET-PET planning and chemo-RT is primarily central. The target mismatch-survival data suggest that using FET-PET planning may counteract the possibility of BTV-related progression, which may have a detrimental effect on survival.

Twice-Weekly Hypofractionated Intensity-Modulated Radiotherapy for Localized Prostate Cancer With Low-Risk Nodal Involvement: Toxicity and Outcome From a Dose Escalation Pilot Study

PURPOSE To evaluate the toxicity and preliminary outcome of patients with localized prostate cancer treated with twice-weekly hypofractionated intensity-modulated radiotherapy (IMRT). METHODS AND MATERIALS Between 2003 and 2006, 82 prostate cancer patients with a nodal involvement risk ≤20% (Roach index) have been treated to the prostate with or without seminal vesicles with 56 Gy (4 Gy/fraction twice weekly) and an overall treatment time of 6.5 weeks. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicities were scored according to the Radiation Therapy Oncology Group (RTOG) grading system. Median follow-up was 48 months (range, 9-67 months). RESULTS All patients completed the treatment without interruptions. No patient presented with Grade ≥3 acute GU or GI toxicity. Of the patients, 4% presented with Grade 2 GU or GI persistent acute toxicity 6 weeks after treatment completion. The estimated 4-year probability of Grade ≥2 late GU and GI toxicity-free survival were 94.2% ± 2.9% and 96.1% ± 2.2%, respectively. One patient presented with Grade 3 GI and another patient with Grade 4 GU late toxicity, which were transitory in both cases. The 4-year actuarial biochemical relapse-free survival was 91.3% ± 5.9%, 76.4% ± 8.8%, and 77.5% ± 8.9% for low-, intermediate-, and high-risk groups, respectively. CONCLUSIONS In patients with localized prostate cancer, acute and late toxicity were minimal after dose-escalation administering twice-weekly 4 Gy to a total dose of 56 Gy, with IMRT. Further prospective trials are warranted to further assess the best fractionation schemes for these patients.

Target volume definition in high-risk prostate cancer patients using sentinel node SPECT/CT and 18 F-choline PET/CT.

BackgroundTo assess the influence of sentinel lymph nodes (SNs) SPECT/CT and 18 F-choline (18 F-FCH) PET/CT in radiotherapy (RT) treatment planning for prostate cancer patients with a high-risk for lymph node (LN) involvement.MethodsTwenty high-risk prostate cancer patients underwent a pelvic SPECT acquisition following a transrectal ultrasound guided injection of 99mTc-Nanocoll into the prostate. In all patients but one an 18 F-FCH PET/CT for RT treatment planning was performed. SPECT studies were coregistered with the respective abdominal CTs. Pelvic SNs localized on SPECT/CT and LN metastases detected by 18 F-FCH PET/CT were compared to standard pelvic clinical target volumes (CTV).ResultsA total of 104 pelvic SNs were identified on SPECT/CT (mean 5.2 SNs/patient; range 1–10). Twenty-seven SNs were located outside the standard pelvic CTV, 17 in the proximal common iliac and retroperitoneal regions above S1, 9 in the pararectal fat and 1 in the inguinal region. SPECT/CT succeeded to optimize the definition of the CTV and treatment plans in 6/20 patients due to the presence of pararectal SNs located outside the standard treatment volume. 18 F-FCH PET/CT identified abnormal tracer uptake in the iliac LN region in 2/19 patients. These abnormal LNs were negative on SPECT/CT suggesting a potential blockade of lymphatic drainage by metastatic LNs with a high tumour burden.ConclusionsMultimodality imaging which combines SPECT/CT prostate lymphoscintigraphy and 18 F-FCH PET/CT identified SNs outside standard pelvic CTVs or highly suspicious pelvic LNs in 40% of high-risk prostate cancer patients, highlighting the potential impact of this approach in RT treatment planning.

Automatic segmentation of breast in prone position: Correlation of similarity indexes and breast pendulousness with dose/volume parameters

This study evaluates edited/reviewed automatically-segmented structures of the breast target in patients planned in prone position and their dose/volume effects. Contouring times were reduced using automatic-segmentation. Similarity-indexes and pendulousness showed that targets with Dice values over 0.965 and high pendulousness, presented the best dosimetric results.

In vivo quality assurance of volumetric modulated arc therapy for ano-rectal cancer with thermoluminescent dosimetry and image-guidance

OBJECTIVE To assess in vivo dose distribution using cone-beam computed tomography scans (CBCTs) and thermoluminescent dosimeters (TLDs) in patients with anal or rectal cancer treated with volumetric modulated arc therapy (VMAT). METHODS Intracavitary (IC) in vivo dosimetry (IVD) was performed in 11 patients using adapted endorectal probes containing TLDs, with extra measurements at the perianal skin (PS) for anal margin tumors. Measured doses were compared to calculated ones obtained from image fusion of CBCT with CT treatments plans. RESULTS A total of 55 IC and 6 PS measurements were analyzed. IC TLD median planned and measured doses were 1.81 Gy (range, 0.25-2.02 Gy) and 1.82 Gy (range, 0.19-2.12 Gy), respectively. In comparison to the planned doses all IC TLD dose measurements differed by a median dose of 0.02 Gy (range, -0.11/+0.19 Gy, p=0.102) (median difference of 1.1%, range -6.1%/+10.6%). Overall, 95% of IC measurements were within ±7.7% of the expected percentage doses and only 1 value was above +10%. For PS measurements, only one was not within ±7.7% of expected values (i.e., -8.9%). CONCLUSIONS Image guidance using CBCT for IVD with TLDs is helpful to validate the delivered doses in patients treated with VMAT for ano-rectal tumors.