RA100 Kidney, Bladder, Bone, Reproductive, CNS, Lung

uremia

toxic condition associated with renal insufficiency. blood retains nitrogenous substances

kidney function

keeps us from dehydrating - lose about 1L/day through skin
controls pH
rids blood of toxins

Why is right kidney lower than the left?

Liver. Location around T12/L3 of spine

Most radiosensitive organ in abdomen

kidney

Kidney TD 5/5

2300cGy
kids TDs may be lower around 1800-2300cGy
try to limit below 2000cGy
try to sheild kidney tissue as much as possible

nephrosclerosis

hardening of connective tissues of kidneys caused by hypertension (high bp)

chronic radiation nephropathy

begins 1.5 to 4 years post treatment completion
removal of radiation damaged kidney may be necessary to control blood pressure (due to ischemia)
history of clinical acute nephritis is NOT a prerequisite for chronic phase of disease
hypertension very serious condition for these patients

bladder functions

stores urine until person can void

4 ways to treat bladder cancer

surgery, radiation therapy, chemotherapy, biologic/immunotherapy - or adjunctive

bladder early reaction

mild erythema may appear during first 24 hours post irradiation. slight reduction in bladder capacity and dysuria (pain, burning, increase frequency, and difficulty passing urine) about 3000cGy in 3-4 weeks.

Bladder TD 5/5

6500 cGy constricture/volume loss
TD 50/5 8000

effects on bones

at low energies, bone absorbs more radiation than soft tissue owing to increased density of bone. Also, bone absorption greater for high LET particulate radiations like neutrons

MV

megavoltage, in excess of 1000kV
4-25MV usual treatment range
no selective absorption in bone over soft tissue with MV

issues with treating childrens bones

irradiation of an epiphysis (end of long bone) is likely to result in retarded bone growth. must treat full width of spine to prevent scoliosis

exotosis

bone spur

Osteonecrosis

bone death

endocrine

for production of sex hormones. hormonal effects are of significant concern. more important in females

spermatogonia

immature sperm. more radiosensitive

maturation depletion

the gradual depletion in number of mature sperm cells

male sterility doses

250cGy=temporary sterility. 500-600cGy=permanent sterility
shield testes when possible. or patient can save sperm in sperm bank for future use. even if fertile period post tx, does not exclude possibility of chromosome damage in those sperm

female follicles

small most radioresistant
intermediate most sensitive
mature moderately sensitive

amenorrhea

suspense of menstruation. begins around 600cGy in prepubescent girls. possible genetic changes to ova. may not be present in first offspring, but may be passed to future generations

induced menopause

around 1200cGy in four fractions - usually in breast cancer tx. may carry marked effects on secondary genitalia and sex characteristics

carina

where main bronchi bifurcate from trachea into lungs. located at T4-T5 level of spine

Acute lung reactions

inflammation, transitory response to moderate dose and not clinically significant. will subside 3-4 weeks post tx

acute radiation pneumonitis

possible 2000-2500cGy. 100% chance with 4500cGy in 4 weeks.

acute exudative syndrome

fluid in air sacs. thick white mucus. can spread beyond the tx site. begins 1-3 months post tx

atelectasis

partial or complete collapse of lung. dyspenia, cough, chest fullness, fever. begins 1-3 months post tx

PEEP

positive end-expiratory pressure (oxygen therapy)

steroids for lungs

only provide temporary relief of symptoms, they do not prevent or reverse the fibrotic changes in the lungs. must be weened off, otherwise withdrawal

esophogeal stricture

may occur as a late reaction to irradiation of the lungs. the radiation causes fibrosis 2-12 months post tx. steroids do not help

Lung TD 5/5

1750cGy Pneumonitis TD 50/5 2450cGy

MOPP

combination chemotherapy regimen used to treat hodgkin’s lymphoma:
Methotrexate
Oncovin
Prednisone
Procarbazine

renal parenchyma

functioning part of the kidney that filters blood and makes urine

Radiation Nephrosis/Nephropathy

slow progressing, non-inflammatory disease. severity dependent on volume of renal parenchyma irradiated, total dose, fractionation schedule, age of pt, associated conditions (hypertension, diabetes) and chemo agents (cisplatin & methotrexate less severe). dates back to at least 1899

acute radiation nephrophathy

6-12 months post tx
hypertension most important prognostic sign
symptoms: high bp, edema, proteinuria, anemia, uremia
about 30% die
doses 2300cGy in 5 weeks result in this condition in 50% of pts

IVP

intravenous pyelogram involves injection of contrast agent (60ml Isovue) into a vein. used to localize kidneys and ureter. can be done during sim

bladder late stage reactions

fibrotic changes to bladder wall around 5000cGy causing reduced bladder capacity

ureters TD 5/5

7500 cGy TD 50/5 10000 cGy Fibrosis

Nephritis

inflammation and sclerotic lesions of kidney

ischemia

temporary deficiency of blood supply

anemia

reduction in the number of red blood cells

Bone Growth TD 5/5

1000cGy (800cGy for kids under age of 3) TD 50/5 3000 cGy

doses above 2000cGy produce significant risk for growth arrest, deformity, bone spurs, and tumor induction
doses above 5000 cGy death of osteocytes occurs
bone necrosis may follow a serious complication
fractures, infection, fistula formation and pain are common
anemia may occur if severe damage to bone marrow

Adult Bone TD 5/5

Femoral Head 5200cGy TD 50/5 6500cGy Necrosis
TM joint mandible 6000cGy TD 50/5 7200cGy distinct limitation of joint function
threshold reduced if patient receiving concurrent chemo
other endpoint symptoms include: pathologic fractures, infection and fistula

vertebroplasty

minimally invasive procedure where bone cement is injected into a cracked vertebra to stabilize the spine and relieve pain. many people go home same day

spermatozoa

mature, non-dividing, radioresistant sperm

individual nerve cells

very radioresistant. fully mature and differentiated, do not enter mitosis. once destroyed, rarely replaced.

transient symptoms CNS

nerve cells vulnerable to radiation damage when supporting tissues, esp small blood vessels upon which they depend for O2 and nutrients, are compromised

acute and subacute may develop early, but permanent and disabling system damage may not be evident for months to years post tx

radiation obliterative endarteritis

chronic inflammation leading to the occlusion of arteries. often a late side effect of radiation therapy. characterized by damage to the blood vessels supplying tissues. this is the limiting factor for CNS TD

encephalophathy

any dysfunction of the brain. marked by varying degrees of impairment of speech, cognition, and arousal

acute encephalopathy

most commonly observed. consists of headaches, nausea, vomiting, somnolence. worsening neurologic signs may accompany first or second fraction, particularly when there is increased intracranial pressure and pt has not been given adequate steroid prep several days in advance. this condition lessens with subsequent fractions and steroid treatment

Somnolence

prolonged drowsiness, sleepiness, or trance like condition

early delayed encephalopathy

occurs in first 2-4 months post tx. children may experience somnolence syndrome may follow prophylactic whole brain tx for leukemia. improves over time and more rapidly with steroids. in adults, syndrome must be distinguished by CT scan for recurrent or growing tumor

late delayed radiation damage

months to years after high dose radiation therapy to brain. progressive dementia without focal signs is main characteristic. may also develop unsteady gait

cervical spinal cord

most radiosensitive part of CNS - hypothalamus and brainstem. effects apparent 6-12 months post tx. late effects are fibrosis, loss of cerebral white matter (demylenation), vascular damage, and necrosis

radiation myelophathy

radiation induced pathologic condition (injury) to spinal cord. likelihood influenced by total dose, size of fraction, and volume treated. equivalent to cerebral necrosis. sensory and motor signs referable to a single cord level, often indivative of a hemi section of cord with brown sequard syndrome.

brown sequard syndrome

Caused by an injury or damage to one half of the
spinal cord with resultant same side (ipsilateral)
paralysis as well as loss of pain/temperature
sensation on the opposite (contralateral) side

early transient radiation myelitis

inflammation of spinal cord & lhermitte’s syndrome. occurs 2-4 months post tx and may last up to 6 months. characterized by numbness, tingling, electric shock like sensations.

late irreversible myelopathy

seen when cord tolerance exceeded. occurs for year or more (up to 30 months) post tx. considered severe complication terminating in paralysis or paresis (partial paralysis) affecting lower extremities first.

late delayed meylopathy

similar to late irreversible and follows tx of extra-spinal tumors (hodgkins) by months or years. progressive weakness and sensory loss similar to brown sequard syndrome

CNS TD 5/5

Whole Brain 4500 TD 50/5 6000 Necrosis

Brain Stem 5000 TD 50/5 6500 Infarction

20cm or TD 50/5 10cm myelitis

Spinal Cord 4700 TD 50/5 7000 Necrosis (myelopathy)

larger volumes not tolerated well. standard daily fraction 180cGy. 200cGy fraction considered “safe” limit

whole brain treatment guidelines

3500cGy in 10 fractions

4500cGy in 20 fractions

5000cGy in 25 fractions

5400cGy in 30 fractions

time dose estimates: 3650-4700cGy in 3 weeks biologically equivalent to 4500-5000cGy in 7 weeks

3 objectives treating whole brain

curative, palliative, prophylactic

infarction

area of tissue (organ) undergoes necrosis following loss of blood supply to area. may occur from stenosis or occlusion

CNS concurrent medications

chemo (adriamycin) have been known to have a radiation enhancing effect. vincristine is neurotoxic

CNS Other Issues

time dose relationship is critical. cerebral changes after tx often mimic residual or recurrent tumor on CT

decline in intellectual function has been related to cranial irradiation in adults and particularly children

radiation induced endocrine deficits include changes in hypothalmic and pituitary functions

rarely, radiation may produce new tumors

spinal cord compression is common on call emergency

radiotherapy for oncologic emergencies

require radiation treatment within a few hours of diagnosis

may occur outside regular hours - weekends/holidays

may include malignant spinal cord compression, brain metastases, superior vena cava obstruction, acute airway obstruction, and uncontrolled tumor hemorrhage

emergency spinal cord compression

occurs in approx 20,000 pts per yr in US/ 5-15% of all cancer pts

untreated would lead to paralysis, sensory loss, or loss of anal sphincter control

most commonly caused by metastatic breast, lung, or prostate cancer

common sites: thoracic 70%, lumbosacral 20%, cervical 10%

time is critical. radiotherapy and/or surgery standard of care.

typical rad field is two normal vertebrae above and below margins of epidural tumor. no est. optimal dose or fraction schedule. recurrance higher for short course than long course. poor survival prognosis short course 1-5 fractions considered appropriate

side effects nausea, esophagitis, diarrhea. antiemetics prior to tx encouraged

emergency increased intracranial pressure