Abstract

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

ijnm-20-4-oral003

Oral 3

122004

204105109

ijnm-20-4-oral003-001

Radiation Safety Aspects of Self Shielded Cyclotron-RDS 111 Eclipse (Siemens-CTI)-First Indian Experience

Prasanna

M Kumar

Gada

Atul

Phani

A Raju

Naresh

Anjaneyulu

Vipin

Apollo Gleneagles, Jubilee Hills, Hyderabad

AbstractAim

To evaluate the efficacy of the shielding and radiation safety aspects during production of F¹⁸ and maintenance.

Materials and Methods

Siemens CTIRDS 111 Eclipse is a compact self-shielded cyclotron for production of Positron Emitting Isotopes. System includes 11MeV negative ion proton accelerator with high yield HP and moderate yield RD target systems and options to run either single or dual mode. Our regular production involve run for one or two hours of bombardment at 40/60µA beam current based on patient schedules.

Radiation measurements were performed during daily operations, maintenance, and delivery of F¹⁸ from cyclotron to FDG explora synthesis unit using pre-calibrated Ludlum survey meter, contamination monitor and digital area monitor. Personnel monitoring was also performed using Canary II Personal digital Pocket dosimeters and TLD. The results were tabulated and analyzed.

Conclusion

Our experience of first 88 runs reveals adequacy of the shielding and excellent design features with minimum hazards and minimal manual intervention to optimize radiation protection to the personnel and the environment with controlled work practice.

ijnm-20-4-oral003-002

FDG PET+CT Imaging for Pre and Post Operative Evaluation in Gynaecological Malignancies

Singh

Natasha

Krishna

Department of Nuclear Medicine, P.D. Hinduja National Hospital & Medical Research Centre, V.S. Marg, Mahim, Mumbai 400 016, India

AbstractAim

To study the role of FDG PET + CT scan in the pre and post operative evaluation in gynaecological malignancies.

Materials and Method

A total of 14 patients with gynaecological malignancies were studied from June 2003 to September 2005. One of these patients was in the pre-treatment staging group, while the rest of the 13 patients were on follow up in the post-treatment period with CA-125 levels and routine CT scans/sonography. Within the patients on follow up; 2 patients (in group I) had rising CA-125 levels with no disease seen either on CT scans or sonography, 5 patients (in group II) had raised CA-125 levels with suspicious lesions on CT scans, and 6 patients (in group III) had normal CA-125 levels with inconclusive findings on CT scans/sonography. Whole body PET + CT imaging was performed with 10mCi FDG.

Results

In the patient within pre-treatment group, the PET scan did not show any evidence of disease elsewhere, hence was not upstaged. In the post operative follow up group; one patient of group I revealed presence of disease in the presacral, pararectal lymph nodes and caecal region, while PET scan was false positive in the other patient. In group II of 5 patients, FDG PET scan was positive in 4 patients. In 2 of these four patients there was upstaging of the disease, while in the other 2 of four patients there was no evidence of disease elsewhere, and in 1 patient the PET scan was false negative. In group III of 6 patients, PET scan was positive in 2 patients, negative in 2 patients and false positive in 2 patients.

Conclusion

The study demonstrated detection sensitivity of 88% in the context of recurrence and staging, and changed the approach towards management in 35% of the patients.

ijnm-20-4-oral003-003

Prediction of Post Operative Pulmonary reserve in Lung Resection Patients

Krishnakumar

Lakshmanan

Priyadarshni

ElumalaiRengarajan

Department of Nuclear Medicine, Cancer Institute (WIA), Adyar, Chennai, India

Abstract

We have performed Ventilation/Perfusion scans for those patients who undergo thoracotomy for resection of primary or metastatic lung tumors. We have predicted post operative FEV1 (Forced Expiratory Volume in first second) using Differential Lung Analysis software.

Methods

42 patients were evaluated with V/Q scans. Ventilation scan was performed with Tc99m DTPA Aerosol and Perfusion Scan using Tc99m MAA on 2 different days. The numbers of counts in anterior and posterior views of V/Q scans were calculated individually. Using Differential Lung Analysis software anterior and posterior arithmetical mean calculation was done and post operative FEV1 was predicted. Most of the patients had lower counts in the ventilation scan and these counts were related to preoperative FEV1. Depending on the volume of lung resection namely Upper, Middle and Lower zones or Total Pneumonectomy FEV 1 was calculated. Whenever FEV1 was >1 (L) they were taken up for resection if there were no other risk factors. (Other risk factors were cardiac complication, chronic obstructive pulmonary diseases, any other pathological conditions involving the contra lateral lung.

Results

More than 50 % of our patients (out of 42) were taken up for lung resection based on our FEV1 predictions.

Conclusion

Postoperative FEV1 based on V/Q scan and pulmonary function tests have helped us to proceed with lung resection while assessing pulmonary reserve.

Key wordsFEV 1PulmonaryV/Q scan

ijnm-20-4-oral003-004

Mapping of Radiation Dose Levels in an Unshielded Medical Cyclotron Vault

Rohatgi

¹Gaur

¹Soni

²Sanaye

¹Dhiaryawan

¹Sethulakshmi

¹Radiological Physics & Advisory Division, BRIT Bhabha Atomic Research Centre, Mumbai-400 094²Medical cyclotron facility, BRIT Bhabha Atomic Research Centre, Mumbai-400 094

Abstract

Recently, medical cyclotrons have become very popular in our country. It is because of the use of cyclotron-produced radionuclide in PET (Positron Emission Tomography) especially ¹⁸FDG, which provides vital clinical information in the field of oncology, neurology, cardiology and in bio-medical research. In medical cyclotrons, high-energy proton or deuteron beams ranging from 11 MeV to 18 MeV is accelerated to bombard on suitable targets to produce positron emitters such as ¹⁸F, ¹1C, ¹⁵O and ¹³N. Medical cyclotron facilities are generally either self shielded or unshielded which is kept in a bunker type vault to minimise the radiation level produced during reaction such as prompt gammas, neutrons, annihilation gammas and induced activity. This is of paramount importance to keep the radiation levels to the occupational workers and the public within the permissible levels. The shielding provided for these facilities takes into account the total workload and the nature of occupancies around. The aim of the study was to evaluate the doses in an unshielded GE PETtrace cyclotron having 16.5MeV beam energy when it is in operation.

In medical cyclotron, neutrons of energy spectrum from 0 to 10 MeV (Avg energy 2.1 MeV) are generated by (p, xn) reaction. Prompt g of energy up to 8 MeV are generated during operation. Gamma dose measurements were made using LiF:Mg,Cu,P Thermoluminescent Dosimeters (TLD) powder encapsulated in a plastic capsule. The response of these TLDs is independent of energy and near tissue equivalent. These capsules were pasted on different locations in the vault around the cyclotron machine and outside the vault to accumulate radiation dose over a period of 24 hrs which includes one hour irradiation time at 40mA with approximately 74GBq of ¹⁸F production. Another set of capsules were pasted for 16 hrs and removed before the operation of cyclotron to evaluate the average induced activity around the target. Fast neutron dose rates were measured during the operation of the cyclotron using CR-39 foils in the maze of the vault and outside the vault.

The cumulative gamma radiation levels evaluated using TLD were 3000 mS v near the target and 40 mS v at a distance of 5 m from the target inside the vault. The dose near the target was 3400 mSv while the induced activity dose was a 2400 mSv. At 180° from the target the cumulative gamma dose for 24 hrs was 58 mSv while induced activity dose was only 0.3 mSv. It was observed that induced activity was highest near the target whereas in other areas the dose was high mainly during the operation of cyclotron. Similarly, neutrons are emitted only during operation of the machine. The neutron levels measured outside and inside the maze were 22 µSv/h and825 µSv/h, respectively. The shielding thickness of the vault on all sides of an unshielded cyclotron can vary from 1.75-2.0 M of boronated concrete wall with a maze for entrance to the vault.

Key wordsmedical cyclotron vaultmapping of radiation dose levelsinduced activityThermo-luminscent dosimeterCR-39 foils

ijnm-20-4-oral003-005

FDG-PET in Recurrent and Metastatic Prostate Cancer: a Comparison with Bone Scintigraphy

Tiwari

¹Nair

¹Jangra

¹Tongaonkar

¹Radiation Medicine Centre (BARC), Oncology, Tata Memorial Hospital, Parel, Mumbai-400 012²Department of Surgical, Oncology, Tata Memorial Hospital, Parel, Mumbai-400 012

Abstract

Prostate cancer is one of the most common malignancies in elderly men. Development of an accurate and effective technique to detect recurrent and metastatic disease is critical for effective management. Well established techniques like bone scan (BS), computerized tomography (CT), magnetic resonance imaging (MRI), assessment of Gleason score (GS) and estimation of tumor marker like prostate specific antigen (PSA) are used for screening of prostate cancer. ¹⁸F-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG-PET) for malignancy has been introduced as a technique for metabolic imaging based on the facts that cancer tissue consumes a large amount of glucose as an energy source and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) enters cancer cells by the same route as glucose, which gets trapped in the cells. ¹⁸F-FDG has already been applied for metabolic imaging of various neoplasms. Reports are also available on the use of ¹⁸F-FDG-PET for prostate cancer. The purpose of our study was to evaluate the diagnostic utility of ¹⁸F-FDG-PET in confirmed cases of prostate cancer and to compare the results with bone scan findings.

The study included 16 patients (age range 55-83 years) with confirmed diagnosis of prostate cancer irrespective of the stage of the disease. Three patients had undergone bilateral orchidectomy, one had hormonal therapy, 9 had undergone both and 3 patients had no therapy. All patients underwent wholebody bone scan and ¹⁸F-FDG-PET scan within one week. Serum PSA levels and GS were assessed in all patients. Assessment of bone scans and ¹⁸F-FDG-PET images were carried out by two experienced Nuclear Medicine Physicians. Abnormalities on ¹⁸F-FDG-PET were compared with that of bone scan on a lesion-to-lesion basis and vice-versa.

In present study total 197 osseous lesions were evident on bone scan. ¹⁸F-FDG-PET could detect 97 (49%) lesions only. In three patients ¹⁸F-FDG-PET results agreed with that of bone scan. Most of the undetected lesions were on ribs. In four patients ¹⁸F-FDG-PET detected extensive involvement of the disease in bone marrow, which was not evident on the bone scans. ¹⁸F-FDG-PET also identified lymph node metastases at various sites in 8 patients, liver metastases in two patients and lung metastases in one patient.

The results indicate that ¹⁸F-FDG-PET could detect less number of osseous metastases compared to bone scan. Since bone scan is not very specific to metastatic lesions, the actual sensitivity of ¹⁸F-FDG-PET may be higher than what is reported. It could also detect the soft tissue involvement of the disease with good sensitivity, which may be important in the management of prostate cancer.

Key wordsMetastasesBone scan¹⁸F-FDG-PETProstate cancer

ijnm-20-4-oral003-006

Visual & Quantitative Assessment of Silent Ischemia by Stress Myocardial Perfusion Scintigraphy in Essential Hypertensives with/without type 2 Diabetes

Padma

Sundaram

Haridas

Kamath

Kumar

Depts. of Nuclear Medicine & Adult Cardiology* Amrita Institute of Medical Sciences, Cochin-26, Kerala

Abstract

Hypertension is twice as common in diabetics as with others. Only 25% of patients with hypertension have adequate control of their blood pressure. Patients with diabetes & hypertension are at high risk for complications. Early identification of these high-risk patients enhances better survival due to early institution of medical/surgical management. Our aim was to prospectively assess the impact of Type 2 DM & how it modifies the prevalence & severity of silent CAD in HT patients.

Materials and Methods

453 asymptomatic HT/HTDM patients (304: 149 M: F) > 50 yrs age with no previous documented infarction were studied from Jul 03 to Jul 05. All patients underwent a 9/27 mCi same day stress/rest gated protocol. Patients unable to perform treadmill were taken up for pharmacological stress (adenosineordobutamine). SPECT imaging was performed using a dual head variable angle (76°) Gamma camera.

Studies were evaluated visually & perfusion severity quantitated using a 5-point scoring system independently by 2 experienced physicians oblivious to each other's interpretation. 20-segment myocardial model analysis of SPECT images was studied for perfusion defects myocardial ischemia severity was evaluated by obtaining the SDS (Summed Difference Score), which is the difference between SSS & SRS (Summed Stress Score & Summed Rest Score).

Results

906 SPECT images were analyzed. Abnormal SSS was found more in HTDM than HT pts (118-39% Vs 37-25% p=0.001). SDS score was much higher in HTDM pts than HT signifying ischemia (p<0.001). There was a greater incidence of silent non-Q wave infarcts in HTDM pts (37/149 25%). Similarly, severity of silent ischaemia was also high in HTDM pts (p=0.001).

Conclusion

Prevalence of IHD is more common in hypertensives as a whole. Incidence of silent ischemia & infarct is more prevalent in HTDM pts than in HT. Early identification of this high-risk population can drastically reduce the future cardiac event rates.

ijnm-20-4-oral003-007

Pain Treatment in bone metastases with Samarium-153

Lange

Knappschaftkrankenhaus Recklinghausen, Germany

Abstract

Using Samarium-153, we treated 41 Patient, suffering from multiple bone metastases of mammary and prostatic carcinomas. The radionuclide is accumulated in bone metastases, it has a half-life of 1,93 days, and it mainly emits electrons (640 to 810 keV) reaching a maximum distance of 3,4 mm. A small amount of the energy is emitted via photons (103 kV), which enables visualisation of the accumulation pattern by bone scans. Quadramet (153-Samarium-Lexidronam-Pentanatrium) was slowly injected intravenously, using a dose of 37 MBq per Kg BW. Four to seven days later pain relief was considerable in 75 % of the patients and was measured by the algometer method. A reduction of Morphine medication was possible in almost 85% of the patients and mobility was improved in 40%. Side effects, as bone marrow suppression, assessed by blood counts, was small. We will explain the therapeutic mechanism of the method and report on its clinical use and results.

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Verification of Left Ventricular Volume Using Balloon for Gated Blood Pool SPECT

Danie

B Heck Kingslin

¹Devakumar

¹Regi

Oommen

¹Vijit

Cherian

¹Departments of Nuclear Medicine, Christian Medical College, Vellore, India²Cardiothoracic Surgery, Christian Medical College, Vellore, India

AbstractIntroduction

The estimation of end-diastolic volume and end-systolic volume of left ventricle in patients with ischaemic heart disease and heart failure and comparison with cardiac MRI is one of the important research areas in Nuclear Medicine. This has become particularly useful and also critical for the recently introduced ventricular remodeling surgery for heart failure. In this study, using a Mannequin endoventricular shaper balloon (Chase Medical Inc.), we verified the method of estimation of left ventricular (LV) volume with GBPS (gated blood pool SPECT)

Method

A balloon with known volume of 100 ml in the shape of left ventricle was used for this study. It was kept inside a Jaszczak phantom to roughly simulate the thorax of human body. The balloon was in the same orientation of heart as in the human body. 37 MBq of Tc99m was mixed with water and filled inside the balloon to simulate the activity inside the left ventricle. This is approximately the activity inside the left ventricle of patients during a regular Gated Blood Pool SPECT (GBPS). 2 MBq of Tc99m was mixed with water and filled inside the Jaszczak phantom to simulate the background activity.

SPECT acquisition of balloon was done in two different protocols using GE Infinia with Hawkeye Gamma camera. In the first protocol the regular SPECT protocol with one emission window was used. In the second protocol SPECT-CT was done with two emission windows. One emission window was centered around the photopeak of 140 keV and the other window was centered around 120 keV and used as scatter window. 64 x 64 matrix was used with zoom 1.3.60 projections were acquired in step and shoot mode. Acquisition duration was 3 seconds for each projection. The duration of acquisition was based on the duration of acquisition for a frame in an 8 frames per cardiac cycle in patient studies which is approximately 3 seconds. The pixel size was 6.8 mm, which is the value regularly used for GBPS. CT acquisition was done with 140kVp and 2.5mAs.

Projection images were transferred to a processing workstation. Slices of the balloon were reconstructed using filtered backprojection algorithm. Reorientation was done to get short axis slices of the balloon, As done for myocardial SPECT processing. Automatic region of interest was drawn with 50 % threshold. The total number of voxels from all the short axis slices were calculated. The volume of the ventricular cavity was calculated from the voxel volume and the number of voxels. The projections were also reconstructed with Ordered Subset Expectation Maximization (OSEM) with attenuation and scatter correction.

Results

The estimated volume of the balloon was 106.6ml which was close to the actual volume of 100 ml. When the threshold was changed, the observed change in the volume was very high. The estimated volume from the images of two different types of reconstruction were nearly the same.

Conclusion

The estimation of left ventricular volume would be fairly accurate with Gated Blood Pool SPECT. With the use of precise region of interest and threshold, accuracy was enhanced.

Key wordsGated Blood Pool SPECTLV volume

ijnm-20-4-oral003-009

Relevance of Whole Body ¹⁸F FDG PET-CT Imaging in Carcinoma of Cervix

Shah

Sneha

Luthra

Seema

Rangarajan

Purandare

Samuel

Bioimaging Unit, Tata Memorial Hospital, Parel, Mumbai, 400012, India

AbstractAim

To justify the need for whole body ¹⁸F FDG PET-CT study in cases of Carcinoma Cervix.

Method

37 patients (6 pre and 31 Post Therapy) with Ca Cervix who underwent PET-CT (GE Discovery ST) between February to May 2005 were retrospectively analyzed. The analyses were done by grouping the studies according to the regions involved - nodal, systemic and skeletal disease. The nodal groups were further subgrouped into those with local pelvic (common iliac, external iliac and internal iliac), below diaphragm, above diaphragm nodal disease. The group under systemic involvement included those which had lung, spleen and/or soft tissue involvement. The patients with skeletal involvement were categorized according to the number of lesions.

Observation

A total of 86 lesions were identified in these studies were analyzed. Of the total nodal lesions 20 lesions were present in the local nodes (23.26%). 12 lesions represented nodes below diaphragm (13.25%) and 24.2% of the lesions (21) were in nodes above the diaphragm. 33 lesions (38.37%) accounted for skeletal lesions. 13 patients showed local lesion in the primary; 6 in pretreatment and 7 post treatment suggesting persistent disease.

Conclusion

62.37% of the total lesions picked up accounted for above diaphragm and distant skeletal metastases, which would have not been identified if only a loco regional assessment would have been done. Similarly in the post treatment scenario other organ involvement would have been missed too. Thus a whole body PET-CT for identifying distant nodal metastases and system organ involvement in a single study appears as a cost effective tool and reduces radiation burden considerably by avoiding multiple region contrast CT.