Médecine Nucléaire et Radiothérapie

The Radiotherapy technologies are one of the most common treatments for cancer, they have been successfully used to damage cancer cells, with as little harm as possible to nearby healthy cells, however Secondary cancer risk following radiotherapy is an increasingly important topic in clinical oncology with impact on treatment decision making and on patient management. The paper aims to investigate and evaluate the current practice in radiotherapy through its different phases and to quantify the risk of secondary primary cancer following radiotherapy in breast cancer by dose calculation and risk estimation of second cancer; to make recommendations for a safer practice in radiotherapy department. The data collected from NBGUH and RHUH with dosimetry calculations on retrospective female patient’s files and verifies with dose measurements on RANDO Phantom.
The results showed 85% of compliance in radiotherapy safe practices, calculated Probability of Causation after breast radiotherapy for contralateral and Ipsilateral breast cancer 0.17%, and for lung is 32%, for spinal cord is 24%. While the PC in phantom measurements in Ipsilateral lung 43.22% and PC for contralateral lung 3.099%.

Objective: To analyze the profile and the diagnostic contribution of pediatric nuclear medicine examinations realized in Senegal.

Materials and methods: Retrospective study having included all the files of scintigraphy examinations realized from June 15th, 2009 to June 14th, 2017 for children from 0 to 15 years old in the service of nuclear medicine of the General Hospital Grand Yoff in Dakar.

Results: The examinations had concerned 43 children or 3.6% of the patients explored in the service. They were mainly male (65.1%) and their middle age was of 8.1 years with extremes of 2 months and 15 years. Near 3/4 applicants were pediatricians or a surgeons-pediatrician. Scintigraphies were renal (67.4%), thyroid (18.6%) and bones (14%). Clinical indications were dominated by hydronephrosis (38.3%) for renal scintigraphy, goiters (50%) for thyroidal scintigraphy and non-traumatic hip pathologies (66.7%) for bone scan. Renal scintigraphies had found 9 cases of renal failure of which a bilateral one. The functions of renal filtration separated were symmetric in 31% and asymmetric in 37.9%. The renal drainage was altered for 37.9% of right kidney and 58.6% of left kidney with an ascendancy of the functional retentions. The arguments suggestive of Basedow disease were found in 50% case for the thyroid scintigraphies, of femoral osteonecrosis and osteo-articular infection in 33.3% each for bones scans.

Conclusion: Nuclear pediatrics examinations although weakly realized has a decisive diagnostic contribution in the pediatric care in Senegal.

Background: RapidArc®, the Varian solution of Volumetric-modulated arc therapy (VMAT) is currently used in the curative treatment of localized prostate cancer. The aim of this study was to evaluate the dosimetric parameters (effectiveness and efficiency) of the arc dynamic therapy at the Teaching Hospital Mohamed V.
Materials and methods: Thirty two patients were treated with curative intent, between June 2013 and December 2014, for localized prostate cancer with RapidArc. Computed tomography (CT) based treatment planning was performed in the supine position with immobilization devices. The patients were instructed to have a comfortably full bladder and an empty rectum at CT acquisition and before each treatment. Delineation of target volume and organs at risk (OARs) was based on the consensus recommendations of the RTOG. The dose prescription was performed with simultaneous integrated boost (SIB) method. Data was collected from dose-volume histograms (DVH) either for planning target volumes (PTV2) or OARs. We calculated the homogeneity index (HI) and the conformity index (CI). We also reported acute and late toxicity related to radiation therapy.
Results: The mean age was 66.63 ±7.24 years old. Of the 32 patients, 24(75%) defined as high-risk. All PTV received dose ranging from 95% to 107% of the prescribed dose. The homogeneity and conformity index was very close to 1 of all treatment plans. The dose limits were respected in all OARs as recommended in QUANTEC reviews 2010. Respectively, the analysis of the HDV in the rectum and the bladder found a V70 at 7.15 ± 5.63% and 16.88 ± 8.62% and a V60 at 16.32 ± 7.97% and 27.68 ± 10 32%. The V50 in the femoral heads was 0.39 ± 0.57% on the right and 0.71 ± 1.35% on the left. The V50, V40 and V30 in the bowel bag were 38.76 ± 39.73 cc, 155.38 ± 85,60 cc and 320.09 ± 180.41 cc, respectively. The mean MU was 555.94 ± 86.34 and delivery treatment time (min) was 1.99 ± 0.47. After three months of radiation therapy, no grade 3 or 4 toxicity was reported. The median control PSA was very low at 0,052 [0.012, 0.417] ng/ml.
Conclusion: This present study demonstrated that RapidArc showed optimal PTV coverage and the best OARs sparing with less number of MUs and short treatment time. Acute GI and GU toxicities were very low. Further studies are needed to evaluate late toxicities and tumor control.

Prostate cancer (PCa) has a unique tropism to bone. Indeed, bone is the most frequent site of distant metastasis and cause of morbidity due to skeletal complications. 99mTc-Methylene diphosphonate (MDP) bone scintigraphy/ scan (BS) is the current standard imaging due to increase adsorption of the tracer at osteoblastic sites. However, it has limited specificity due to false positives in degenerative changes, benign causes and false negatives in bone marrow metastasis and lytic lesions. Another drawback of BS is flare response. Prostate Specific Membrane Antigen (PSMA) has been the most studies target in prostate cancer imaging in recent time due to 100-1000 time overexpression in cancer cells. 68Ga-PSMA-11, a small molecule with PSMA enzyme inhibition activity has been found promising in recurrence and lymph-node staging. In our experience of 97 staging prostate cancer patients, PSMA PET-CT showed 57.41% with pure sclerotic metastasis. Mixed (33.33%), marrow (7.14%) and lytic (2.3%) types of lesions constitute the rest and thus BS alone in these patients may leads to underestimation of bony disease burden. PSMA has not been found positive in degenerative changes however its role in response to anti-androgen needs caution due to know synergistic effect on PSMA expression. We concluded, PSMA PET-CT would have better sensitivity and specificity due to unique distinction for detecting non-sclerotic metastases. We presumed if PSMA has been performed for staging workup then there is limited role of BS except in clinical trial patient. Overall PSMA PET may become one-stop-shop for PCa workup.

Background: Rest-Redistribution thallium(R-RD Tl) imaging has high negative predictive value (NPV) but low positive predictive value (ppv) for the prediction of recovery of regional myocardial dysfunction after revascularization (Rev). Combining myocardial perfusion (MP) and functional data with nitrate-enhanced gated SPECT MIBI (GSM) at rest appears to be a promising approach for viability detection.

Aim of the Study: Differentiate between clinical and academic viability.

Methods: Total of 66 patients with CAD underwent R-RD Tl,2 sets of resting GSM using 2 MIBI injections, and echocardiography at rest andafter low dose dobutamine (LDD). One hour before GSM2, trimetazidine (TMZ) andnitrate, had been given. All pts had their echo repeated after (Rev) as a golden standard for clinical viability one year later. Myocardial biopsy was taken for mitochondrial assessment as a golden standard for academic viability.

Results: 389/1122 segments were found to have abnormal resting wall motion (RWM) on echo. 165/217 hypokinetic, 48/102 akinetic and 6/66 dyskinetic showed contractile response for LDD echo. The MP images showed normal uptake, complete, partial reversibility and poor uptake in Tl, GSM1 and GSM2 images as following:(58,31,47), (36,22,35), (198,119,190) and (32,148,50) of segments respectively. Sensitivity and specificity of Tl, GSM1 and GSM2 and LDD echo for clinical viability had been found respectively to be (94.9%,74.1%), (59.9%,93.6%), (93.5%, 90%) and (78.5%,100%). Mitochondrial degeneration had been found to be more in the segments with partial reversibility and those with poor uptake with sensitivity and specificity of (90,85.6%), (57.2%,94.2%), (89.4%,98%) and (75%, 88.2%) respectively. From this data we can grade viability into 4 grades.

Conclusion: Clinical definition of viability is better looked for in GSM2. Viability could be assessed into 4 grades.

Introduction: Germinomas are malignant intracranial germ cell tumors, usually found in pineal region. These tumors are exquisitely sensitive to radiation. Whole ventricle radiation (RT) with a boost field to the primary tumor is the standard treatment for localized germinomas. RapidArc radiotherapy is considered an excellent technological advance that shows great potential for producing highly conformal doses to treatment volumes.
Case report: We present a case of intracranial germinoma who achieved a partial remission after four courses of chemotherapy induction. The patient received whole ventricular radiation therapy followed by a boost to the tumor and its margin to a total dose of 40 Gy using RapidArc radiotherapy over the course of 5 weeks. Any toxicity has been noted during the treatment. Early post treatment imaging showed a complete response.
Conclusion: This case demonstrates a successful management of localized intracranial germinoma by RapidArc radiotherapy that allowed a highly conformal volumetric dose distribution with optimal sparing of surrounding areas of the brain.

Purpose: To test the reactivity of monoclonal murine IgM and IgG for Tenascin-C (TNC) in formalinized solid human tumors tissue samples and to estimate the radiation dose that Yttrium- 90 labeled murine IgM reactive with TNC can deliver to a solid tumor and tumor containing draining lymph nodes.

Materials and Methods: Using Immunohistochemistry (IHC), mouse anti-human TNC IgM and IgG clones were tested for the detection of TNC in formalin fixed biopsies of patients with Glioblastoma multiforme (GBM), adeno carcinoma of the exocrine pancreas (PaCa)-, breast-, colon-, renal-, ovary- prostate carcinoma, cutaneous-, ocular- melanomas, and Ewing Sarcoma. IHC was performed on all tumors with an n=1, except for PaCa and ocular melanomas, n=11. Monte-Carlo simulation and convolution calculations were used to determine the activity of Y-90 required for delivering 100Gy to a 50 × 50 × 50 mm3 water-equivalent tumor model, assuming a homogeneous distribution of the radioimmunoconjugate throughout the model volume.

Results: IHC has confirmed reactivity of IgM with TNC in all of the tested human solid tumors samples except for ocular melanoma. Positive and negative controls of IgM specificity were used. The dosimetry simulation predicted an Yttrium-90 activity of 217 MBq to deliver a dose of 100Gy to the tumor model with a 6 mm sharp dose fall off in surrounding normal tissues.

Conclusion: Loco-regional control of human solid tumors may be obtained with intra-tumoral administration of radiolabeled IgM targeting TNC. In TNC negative solid tumors such as ocular melanoma, other tumor-specific target(s) need to be identified.