Biological Tumor Volume Research Articles

87 poster: Biological Gross Tumour Volume (GTVB) in Head and Neck Cancer (HNC): Comparison of Automated Segmentation Tools.

87 poster: Biological Gross Tumour Volume (GTVB) in Head and Neck Cancer (HNC): Comparison of Automated Segmentation Tools.

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 18F 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 RTV’s 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.

(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.

18FDG et radiothérapie externe, le point de vue du radiothérapeute.: Application des techniques de fusion d’images à la radiothérapie des carcinomes bronchiques

The prognosis of patients with localized non-small-cell lung carcinoma and treated with radiation therapy remains poor. The three-dimensional conformational radiotherapy aims to increase the dose of radiation at the tumor volume to increase the local control, while sparing the healthy tissue neighborhood. The reduction of the safety margins and the irradiated volumes obliges to determine with most acute precision the exact tumor volume. However, the scanner alone is insufficient, particularly at the mediastinal level and at a distance. The positron emission tomography allows distinguishing a biological tumor volume. It helps to define the lung tumor volume, especially when the tumor is accompanied by atelectasis, and to recover the lymph node staging at the mediastinal level and at a distance. Even if the sensibility and the specificity are not 100 %, positron emission tomography now becomes essential before considering an escalation of thoracic radiation dose.

SU-FF-J-128: An Automatic Method to Delineate 18F-FDG PET Tumor Volumes for Radiation Treatment Planning

Purpose: To develop and evaluate an automatic method of segmenting biological tumor volumes in 18F‐FDG‐PET images for radiation treatment planning. Method and Materials: We developed a method of correcting errors in biologic tumor volume due to the finite spatial resolution in 18F‐FDG PET images. The PET image is acquired, then used to generate a “spillover image”S, defined as the difference between an iteratively deconvolved image and the original PET image. The biologic tumor boundary was defined along the contour where the spillover imageS changes sign. This algorithm was validated with tumors simulated with various sizes (11–28 mm) and background levels, and also with PET/CT images from 10 patients having FDG‐avid head/neck tumors having anatomical boundaries clearly defined with CT. PET‐derived biologic tumor volumes were compared against the CT‐derived anatomic tumor volumes and against the volumes extracted by applying a simple threshold to the PET image.Results: The biologic tumor volumes derived with the proposed method matched the CT‐derived anatomic tumor volumes for all tumor sizes having background activities from 0 to 33% of the tumor activity in the simulated data, and agreed to within 90% for all tumors evaluated in the patient data. For all tumor sizes, the PET volumes derived from this algorithm matched more closely with the CT‐derived volumes than those obtained with a fixed threshold applied to the PET images.Conclusion: The proposed algorithm incorporates the spatial resolution of the imaging system to automatically segment biologic tumor volumes. The algorithm automatically compensates for differences in tumor size and tumor:background contrast, and does not require a fixed threshold to be applied to the PET image. Such a scheme will be useful for defining biologic tumor volumes with 18F‐FDG PET for radiation treatment planning. Research sponsored by Siemens Oncology Care.

Erectile dysfunction following permanent prostate brachytherapy with dose escalation to biological tumor volumes (BTVs) identified with SPECT/CT fusion

Purpose: Evaluate erectile dysfunction (ED) following brachytherapy with dose escalation to biological target volumes (BTV) identified by prostate-specific membrane antigen (PSMA) targeted 111Indium capromab pendetide (ProstaScint) single-photon emission tomography images co-registered with computed tomography (SPECT/CT).

Technology Insight: PET and PET/CT in head and neck tumor staging and radiation therapy planning

The evolving utilization of functional imaging, mainly 2-[18F]fluoro-2-deoxyglucose (18FDG) imaging, with positron emission tomography (PET) and PET/CT, is profoundly altering head and neck tumor staging approaches, radiation treatment planning, and follow-up management. Tumor-node-metastasis staging with PET/CT has improved the characterization of patient disease versus CT, MRI, or PET alone, thereby affecting patient disease management. Therefore, the utilization of PET/CT is appropriate for head and neck cancer staging in the initial presentation and in the recurrent setting. In the setting of radiation therapy treatment planning, PET-directed tumor volume contouring is not ready for clinical practice without further technological improvements in imaging specificity/sensitivity and resolution. Patient or organ motion might interfere with the accuracy of anatomical co-alignment, and variability in defining the threshold of imaging signals on PET images can affect the contour of the biological tumor volume. The use of PET/CT for staging and detecting both primary and recurrent head and neck cancer is valuable; however, its application in radiation treatment planning should be viewed as investigational.

1071: Rectal Toxicity following Permanent Prostate Brachytherapy with Dose Escalation to Biological Tumor Volumes (BTV) Identified with Prostascint and CT Scan Image Fusion

1071: Rectal Toxicity following Permanent Prostate Brachytherapy with Dose Escalation to Biological Tumor Volumes (BTV) Identified with Prostascint and CT Scan Image Fusion

Combination conformal radiotherapy and radioimmunoguided transperineal 103Pd implantation for patients with intermediate and unfavorable risk prostate adenocarcinoma

Purpose To report outcomes for prostate cancer patients treated with external beam radiation therapy (EBRT) and permanent prostate brachytherapy utilizing radioimmunoguided targeting of biological tumor volumes (BTVs). Methods and materials Between February 1997 and October 2001, 66 patients with intermediate- to high-risk prostate cancer underwent EBRT and ProstaScint ®-guided transperineal brachytherapy. Thirty patients received neoadjuvant hormonal manipulation, while 36 patients did not. Median patient age was 66 years (range, 49–78 years). The median follow-up was 41 months (range, 24–78 months). No patients were lost to follow-up. Risk factors (RF) used for risk stratification included PSA >10 ng/ml (35 patients), Stage T2b or greater (22 patients), and Gleason score ⩾7 (55 patients). Results for biochemical disease free survival (bDFS) were reported using the ASTRO consensus definition for biochemical failure, PSA ⩽1.0 ng/mL or PSA ⩽0.5 ng/mL. Survival was estimated by the Kaplan–Meier method. Results Five-year overall survival was 93.1% and 5-year bDFS by the ASTRO definition was 89.3% with a median follow up of 41 months. Patients with intermediate- (1 RF) and high-risk (2–3 RF) prostate cancer exhibited 5-year ASTRO-defined bDFS of 100% and 81.9%, respectively. There was no significant difference in bDFS between the patients treated with or without hormone therapy (HT). The 5-year ASTRO-defined bDFS was 89.8% for the 30 patients treated with HT and 88.9% for the 36 patients who did not receive HT ( p = 0.843). For the patients without HT the median PSA nadir was 0.11 ng/mL. The median time to nadir was 23 months (range, 6–66 months). Conclusions With limited follow-up, the results of EBRT plus radioimmunoguided brachytherapy for intermediate- to high-risk prostate cancer appear favorable. The addition of HT did not appear to affect bDFS significantly, but interpretation is confounded by possible selection bias and the limited power of this study.

Magnetic resonance spectroscopic imaging-guided brachytherapy for localized prostate cancer

Purpose: Prostate brachytherapy (PB) entails the placement of radioactive sources throughout the entire prostate gland to treat localized cancer. Typically, the target volume in PB encompasses the entire prostate gland because of the inability to localize the cancer and the multifocal nature of this malignancy. However, because of the unique biochemical nature of the prostate gland, recent advances in magnetic resonance spectroscopic imaging (MRSI) of the prostate have allowed precise delineation of the cancer location within the prostate gland. This report reveals our initial experience of MRSI-guided PB. Methods: An MRSI study was obtained in 15 favorable-risk (prostate-specific antigen level ≤10 ng/mL, Gleason score ≤6, and clinical Stage ≤T2a) patients before their scheduled PB. The results of this study were used to internally map 7 × 7 × 9-mm volumes of prostate tissue to assign cancerous areas a higher dose of radiation. Such tumor-bearing areas had a low citrate/(choline+creatine) ratio consistent with cancer. On the basis of the anatomic MRI and MRSI correlation, three-dimensional coordinates were assigned to the locations of MRSI-defined cancer. The entire target volume was treated to 145 Gy using 125I. Abnormal citrate regions, termed the biologic tumor volume, were prescribed a dose of 130% of the target volume dose (188 Gy) to dose escalate in the abnormal citrate regions while respecting the normal radiation tolerances of the surrounding areas. Three-dimensional treatment planning was used to perform the implant. Results: Of the 15 prostate cancer patients evaluated, all had successful three-dimensional MRSI acquisition before their scheduled PB procedure. In 14 of the 15 patients planned with MRSI, the data were successfully incorporated into their treatment planning and were used to increase the radiation dose prescription to 130% in the MRSI-defined volumes. In 1 patient, MRSI revealed significant multifocal disease that made focal boosts impractical. Postimplant dosimetry confirmed a median V100 of 95% (range 89–98%) in the 15 evaluated patients for the prescription dose of 145 Gy to the target volume. Furthermore, the median BTV100 for the abnormal citrate region was 90% (range 80–100%) as determined by postimplant dosimetry. Urethral and rectal dose-volume histograms were within normal limits. Morbidity was comparable with that for conventionally treated patients. Conclusion: MRSI offers a promising new approach for the delivery of ionizing radiation in PB. Although this series was small and with a short follow-up, MRSI-guided implants are feasible and warrant further investigation as a means of improving the therapeutic ratio in PB.

Recent progress in optimizing radiotherapy in chemo-radiotherapy for stage III non-small cell lung cancer

It is logical to tailor radiation dose schedule according to the therapeutic goals, i.e., curative versus pal-liative to achieve the best possible outcome for a given clinical condition. Not all patients with stage III served optimally by administering the same dose of radiation or chemo-radiotherapy regimen. The aim of this study is to update the recent progress in the clinical research in escalation of radiation dose/dose intensity and radiotherapeutic/predictive factors of radiation response which may be useful in guiding high dose radiation therapy in chemo-radiation (CT+RT) for beter outcome.The current literatures (1985–2001) on clinical research in escalation of radiation dose/dose intensity were reviewed for radiotherapeutic factors, which are important in tumor response and therapy outcome. Also reviewed were translational research in genetic/radiobiological/metabolic markers for the identification of useful biomarkers in predicting therapy response to radiation therapy or CT+RT. Reports on combined therapy for stage III NSCLC were also reviewed for the toxicity, tumor response and survival outcome.Factors important for predicting therapy outcome in NSCLC are grouped as follows: 1. Radiotherapeutic factors. The major factors of radiation therapy that play the decisive role for successful outcome include the accurately defined target volume, the dose intensity and total dose of radiation which is high enough to provide local tumor control for the majority of patients, and proper treatment planning, preferably three-dimensional (3-D) conformal radiation therapy planning with which the maximum and optimum dose of radiation can be determined within the limit of normal tissue tolerance. 2. Tumor related factors (anatomic factors). The extent of tumor (tumor stage) is one of the most important prognostic factors affecting the therapy outcome. Tumor size (T stage), anatomical structures involved (T4 versus T3 lesion), and the presence or absence of regional lymph node metastasis have a significant impact on both prognosis and response to appropriate therapy. 3. Host-related factors (clinical factors) that are important in therapy response include performance status, weight loss more than 10% of body weight in the previous 6 months, and associated co-morbidities, i.e., pulmonary and cardiac diseases. 4. Radiobiological/metabolic/genetic factors. Biologic markers resulting from genetic lesions in lung cancer are grouped as follows: a) Radiobiological factors—tumor cell proliferation kinetics (Tpot), hypoxia, intrinsic cellular radiosensitivity, gamma factor, DNA content; b) metabolic/enzymatic factors: increased glucose utilization measured with positron emission tomography-fluorodeoxyglucose (PET-FDG) may be a useful marker for therapy response to radiation therapy and chemotherapy, and also for the definition of biological tumor volume as opposed to anatomic tumor volume by computed tomographic scan, and c) genetic factors: allelic imbalance, methylation, gene overexpression, and polymorphisms. Current data indicate that there is a dose-response relationship between radiation dose and local tumor control, and also between local tumor control and survival in stage III NSCLC. Therafore, the radiotherapeutic factors, i.e., total radiation dose, fractionation schedule and dose intensity, the use of 3-D conformal radiation to secure the optimum therapeutic ratio are important for improved local tumor control and survival. Future research should be directed towards radiation dose escalation using 3-D conformal therapy to determine the maximum tolerated dose (MTD) of radiation in a setting of chemo-radiotherapy, and the use of this MTD for improved local tumor control and survival. Radiobiological, molecular, and metabolic markers may offer a potential for monitoring tumor response and optimizing radiation therapy accordingly.